Abstract:
The present invention relates to a rapid method for estimation of Chemical Oxygen Demand (COD) of water, COD is an important parameter for determining the extent of pollution in water bodies, the basic principle of COD estimation is not much different from prior art but the time taken is reduced considerably and the results are equally sensitive and reproducible as other methods and the method used to generate data on the performance of effluent treatment plants in remote areas or rural areas, it also provide regular and sequential information on the quality of effluent generated by food processing industries.

Description:
This application is a divisional of 09/820,538 filed Mar. 29, 2011, now U.S. Pat. No. 6,967,104. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a rapid method for estimation of Chemical Oxygen Demand (COD) of water and wastewater. It particularly relates to determination of COD. of industrial waste or domestic waste water or for determining the degree of pollution or develop designs for effluent treatment plants or efficiency of treatment plants or quick, rapid and onsite estimation of COD of water and wastewater or in untreated municipal wastewater or activation and pre-clarification tank inlets or cooling water and storm water reservoirs. 
     BACKGROUND AND PRIOR ART REFERENCES 
     Oxygen demand is a significant parameter for determining the effect of organic pollutants in water. As microorganisms in the environment ingest the organic material, oxygen is depleted. This in turn can be harmful to fish and plant life. (http://www.spectronic.com/spectron/spctech2.htm). Wastewater from food processing is non-toxic but organic. High concentration of nutrients can be harmful for the environment. Extra quantities of nitrogen, fat and phosphorus require more oxygen for bacteria to decompose. If Chemical Oxygen Demand (COD)/Biochemical oxygen demand (B.O.D) content of the water is excessive, the oxygen supply in the water may be depleted below the level required to sustain aquatic life. (Ref: http://info.rfisk.is/verkefni/1077/hfe4f2.htm). 
     The Chemical Oxygen Demand (COD) determination is a measure of the oxygen equivalent of that portion of the organic matter in a sample that is susceptible to oxidation by a strong chemical oxidant under controlled conditions (American Public Health Association (APHA). (1998). In Standard methods for examination of water and wastewater. 20 th  Edn. American Public Health Association (APHA), American Water Works Association (AWWA), Water Pollution Control Federation (WPCF), Washington, D.C.). 
     The limitation of the test lies in its inability to differentiate between the biologically oxidizable and biologically inert material. COD determination has an advantage over BOD test in that the results can be obtained in less than five hours where as BOD requires 3 to 5 days. Further the test is relatively easy and with not much interference. (American Public Health Association (APHA), 1976). In: Standard methods for examination of water and wastewater. 14th edn American Public Health Association (APHA), American Water Works Association (AWWA), Water Pollution Control Federation (WPCF), Washington, D.C.). 
     The main chemical compounds in wastewater are Chemical Oxygen Demand (COD), nitrogen, phosphorus, fats, oils and grease. COD and BOD — 5 are important parameters for measurement of organic matter content and oxygen needed to decompose the organic compounds. During the decomposition of organic matter there is less oxygen available in the sea and no oxygen in some places. It is possible to calculate COD or BOD into standard personal units, 60 g of oxygen to decompose the organic compounds from one person per day or equaling of 135 g of oxygen to decompose Chemical Oxygen Demand (COD) in waste water (COD=2.25×BOD). (Ref: http://info.rfisk.is/verkefni/1077/hfe — 4f2.htm). 
     The calorimetric dichromate reflux method is commonly used method for determining the Chemical Oxygen Demand (COD) content in a sample, and has been preferred over procedures using other oxidants because of superior oxidizing ability, applicability to a wide variety of samples and ease of manipulation (American Public Health Association (APHA). (1989). In: Standard methods for examination of water and wastewater. 17th edn. American Public Health Association (APHA), American Water Works Association (AWWA), Water Pollution Control Federation (WPCF), Washington, D.C.). The basic principle involved is oxidizing the most types of organic matters by a boiling mixture of chromic and sulfuric acids. A sample is refluxed in strongly acid solution with a known excess of potassium dichromate (K 2 Cr 2 O 7 ). After digestion, the remaining unreduced K 2 Cr 2 O 7  is titrated with ferrous ammonium sulfate to determine the amount of K 2 Cr 2 O 7  consumed and the oxidizable organic matter is calculated in terms of oxygen equivalent. 
     The determination of Chemical Oxygen Demand (COD) is widely used in municipal and industrial laboratories to measure the general level of organic contamination in waste water (Ref: http://www.chemetrics.com/lnstProd/COD.I.htm). 
     Wide ranges of instruments are available for Chemical Oxygen Demand (COD) estimation. CHEMetrics&#39;—employs EPA (Environmental Protection Agency, USA) approved Dichromate reactor digestion method. (http://www.chemetrics.com/InstProd/COD.I.htm). Spectronic Instruments provide SPECTRONIC® Spectrophotometer and the Bioscience ACCU-Test® system based on APHA method. (American Public Health Association (APHA). (1989). In: Standard methods for examination of water and wastewater. 17th edn American Public Health Association (APHA), American Water Works Association (AWWA), Water Pollution Control Federation (WPCF), Washington, D.C.). It uses a semi-micro conversion of the Standard Methods procedure for the determination of Chemical Oxygen Demand (COD). (Ref: http://www.spectronic.com/spectron/spctech2.htm). In the North Dakota Department of Health (NDDH), Chemistry Division Chemical Oxygen Demand (COD) SOP (Ref: http://www.health.state.nd.us/lab/METHODS/I-4.HTM) COD determination is through comparison of absorbance for the standards and the samples in HACH COD reactor and Sequonic Turner model 390 Spectrophotometer. 
     ISCO-STP COD analyzers and the Phoenix analyzer uses ozone for rapid oxidation and provides continuous Chemical Oxygen Demand (COD) measurement corresponding directly to result of the laboratory standard dichromate method. (http://www.isco/html/prdprCOD.html). 
     Among the reference methods of Chemical Oxygen Demand (COD) determination, EPA method 410.1/410.2 and the Standard Method SM5220-D employ closed refluxing (Ref: http://splash.metrokc.gov/wir/enylab/LABGUIDE/cm_ref.htm). The biodegradability test—5-day and 28 day includes COD 5 and 15 day determinations in the reference OCED method 3101D—SOQ Appendix B Methods used by Burlington Research, Inc. (Ref: http://199.72.5.39/sogapb.htm). 
     PASTEL UV® system works exclusively in UV range of light spectrum with UV analyzer (Spectrophotometer). It requires 16 photodiodes and specially developed pulsed deuterium lamp. This analyzer requires calibration for accuracy within a very specific sample category such as industrial wastewater. For each additional application a new base line spectra has to be customized for specific samples. In this method the co-relation is only for BOD and TSS (Total Suspended Solids) which is 90% when compared to the traditional test methods. For COD the co-relation is valid only upto 6000 mg/L COD only. It is a indirect estimation based on reference data stored in internal UV based software (Ref.: http://www.azurenv.com/ispec.htm). The major limitations in different cases are the economics of the methods used, instruments employed and the time consumed. CHEMetrics&#39; uses a standard digester block for heating the sample for 2 h at 150° C. In addition, the method needs to employ a Chemical Oxygen Demand (COD) Photometer (A-1051C) or Spectrophotometer which accepts a 16 mm diameter cell. The major limitation is that the results are not reportable to USEPA. On the other hand, 13 mm cells can be read in CHEMetrics VVR and A1051 photometer. However, the results are good for monitoring purposes only. 
     BioScience&#39;s EPA Accepted ACCU-TEST® method needs specific type of Chemical Oxygen Demand (COD) reagent vials, a heating block, data management software package, etc. are required. It makes each test quite costly. BioScience&#39;s EPA Accepted ACCU-TEST® is available only in a medium sensitivity ranges for Spectrophotometry 5 to 4500 mg/L Chemical Oxygen Demand (COD). In order to use the BioScience COD vials in the SPECTRONIC® 401, both the test tube holder and the Light shield are required where as the GENESYS™ 2 or GENESYS™ 5 require the cell holder Platform and its Test tube holder (Ref:http://www.spectronic.com/spectron/spctech2.htm). 
     In the North Dakota Department of Health (NDDH) Chemistry Division Chemical Oxygen Demand (COD.) SOP (Ref: http://www.health.state.nd.us/lab/METHODS/I-4.HTM) Chemical Oxygen Demand (COD) determination is in a narrow range of 0 to 150 and 150 to 1500 mg/L. The calorimetrically determined Chemical Oxygen Demand (COD) value is based on measuring the consumed oxidant in the chrome (Cr 6+ ) and chromous (Cr 3+ ) valence state. The method employs HACH COD reactor and Sequonic Turner model 390 Spectrophotometer. The spiking solutions in the 0 to 150 mg/L range are 10, 25, 50 and 150 where as for 150 to 1500 mg/L ranges, 5 concentration ranges 100, 250, 500, 1000 and 1500) are employed. It needs a sample volume of 10 ml, in addition to heating for 2 hours at 150° C. 
     In the Manganese III method for Chemical Oxygen Demand (COD) analysis (U.S. Pat. No. 5,556,787 September, 1996) determination is done by using an analysis reagent comprised of a mixture of stabilized Manganese III ion and an inorganic non-oxidizing acid such as sulfuric or phosphoric acid. The method involves titration and calorimetric determination. The method involves digestion of the test sample by heating between 100 to 200° C. for up to 2 hours. 
     A method based on redox cell involved treatment of organic carbon with an excess of an oxidizing agent. The remaining oxidizing agent is determined in a redox cell to ascertain how much of the oxidizing agent was consumed by the organic carbon. This was the COD. This is multi-step process involving a large number of reagents (U.S. Pat. No. 3,930,798 January, 1976). Another redox based method involves ozone as an oxidizing agent (U.S. Pat. No. 5,324,666 June, 1994). The accuracy of the process is limited only by the control range of the ozone generating pumps. It can work within a range of less than 0.5 ozone load i.e. the ratio of chemical oxygen demand to added ozone. By increasing the ozone input the measuring range may be extended upwards but with reduced accuracy. 
     All the methods employed so far have long refluxing or digestion periods and are followed by titration or spectrophotometric reading of the standards and the samples at different wavelengths. 
     In the present invention the major limitations involved in estimation of chemical oxygen demand of water and wastewater have been over come. The novelty of the present invention is in use of a rapid, simple and effective method for estimation of COD of a wide range of samples. Another novelty of the present invention is the reduction in time period taken for estimation of COD, from 2 h to less than 5 minutes. In the present invention, parameters have been studied for preparation of a reaction mixture, which is easy to handle. Another novelty of the present invention is in the use of very small quantities of reagents and the test sample. In the present invention the various reaction mixtures can be read instantly for a very wide range of COD loads by using minor equipment e.g. photometer. Another novelty of the present invention is the ability to conduct the estimation on site, avoiding any possible changes in the test sample quality. Yet another novelty of the present invention is the COD color chart is used for determination of COD. over a wide range. Another novelty of the present invention is the flexibility to use reagents for determination of COD. over a wide range. Another novelty of the present invention is the simplicity for preparing reference standards easily and rapidly. Another novelty of the present invention is the stability of color based reference standards for long period without preserving them at low temperatures. These can thus be used repeatedly. 
     OBJECTS OF THE INVENTION 
     The main object of present invention is to provide a rapid method for estimation of Chemical Oxygen Demand (COD) of water and wastewater, which obviates the drawbacks listed above. 
     Another object of the present invention is to provide a cheap and simple method for quick estimation of COD of water and wastewater. 
     Yet, another object of present invention is to provide a rapid and sensitive method which, capable of determining COD in small quantities of test sample. 
     Yet another object of the present invention is to provide a color chart over a wide range of COD values. 
     Yet, another object of the present invention is to provide a kit for COD. estimation. 
     Yet, another object of the present invention is to provide a method which does not require much technical skill and sophisticated equipment. 
     Another object of the present invention is to provide an effective process for COD estimation with very little loss of sample. 
     SUMMARY OF THE INVENTION 
     The present invention has solved the problem of longer duration and consumption of large quantities of chemicals in COD estimation. The method of the invention has removed the need for heating the reaction mixture for nearly 2 h at 148° C., which is conventionally employed by standard methods and other commercially available kits. 
     One mL of sample solution is mixed with three reagents, consisting of 0.02 g mercuric sulphate, 0.5 mL of 0.25 N potassium dichromate solution and 1.5 mL of sulphuric acid—silver sulphate in a sequential manner. Its COD is checked with the help of color chart. Sample(s) showing a COD value of more than 10000 mg/L are diluted. After establishing its approximate COD value, the sample is diluted further, if necessary, to achieve a COD value in the range of 300 to 500 mg/L. Reagents listed above are added to these diluted sample and read its OD at 585 and 635 nm. These OD values are used for calculating precise COD values by comparing it with standard glucose solution. 
     The main utility of the present invention is for determining the degree of pollution, to develop designs for effluent treatment plants and to determine efficiency of treatment plants. Monitoring of COD is important for design and operation of wastewater treatment equipment. Another utility of the present invention is to provide an efficient method for quick, rapid and onsite estimation of COD of water and wastewater. Other utilities include applications in untreated municipal wastewater, activation and pre-clarification tank inlets, and even cooling water and storm water reservoirs. It is also used as a standard parameter for characterization of wastewater loads or for proof of a required purification level. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The chemical oxygen demand (COD) determines the amount of oxygen required for chemical oxidation of organic matter using a strong chemical oxidant such as potassium dichromate under reflux conditions. The test is widely used to determine: 1) The degree of pollution in water bodies and their self purification capacity, 2) Efficiency of treatment plants, 3) Pollution loads, 4) Provides rough idea of B.O.D, which can be used for B.O.D estimation. The conventional estimation is based on the principle that most of the organic matter is destroyed when boiled with a mixture of potassium dichromate and H 2 SO 4  producing CO 2  and H 2 O. A sample is refluxed with a known amount of potassium dichromate. It is then titrated against ferrous ammonium sulphate. The amount is proportional to O 2  required to oxidize the organic matter. The method takes 2 to 3 hours. Using standard COD kits available in the market can also do COD estimations. The standard COD kit method involves the use of thermoreactor and a photometer can also take 2 to 3 hours to complete. Since the initial COD of the sample cannot be guessed, kits for different COD ranges have to be tried and even sample may still has to be diluted. Dilution of sample leads to further use of more kits, it thus makes the estimation more expensive. However, a technique has been devised here, which gives good estimate of COD within 5 to 10 min and consumes very small quantities of reagents compared to conventional standard methods. It can be carried out easily on site. The reaction mixture develops a color, which can be easily read and distinguished. In the first stage, a sample is added without any dilution. The color developed with the undiluted sample gives a direct estimate of COD or gives a clear indication of the extent to which a sample needs to be diluted before adding to the reaction mixture. For samples with COD value of more than 10000, the color of the sample and the different reagents will be C10000 (brown). Make 4 different dilutions of the sample i.e. 10, 100, 200 and 500. The various diluted samples can be tested in increasing order of their dilution. Once a diluted sample and the reagent mixture show a color between C100 (yellow) and C500 (sea green). This dilution can be 10 to 300 times, depending upon the initial COD of the sample. 
     Accordingly, the present invention provides a rapid method for semi-quantitative estimation of Chemical Oxygen Demand (COD), which comprises:
         i) preparing standard solutions by dissolving glucose in water,   ii) mixing the standard solutions with different reagents, mercuric sulphate (HgSO 4 ), potassium dichromate (K 2 Cr 2 O 7 ) and sulphuric acid (H 2 SO 4 ) silver sulphate reagent in a sequential manner.   iii) mixing the sample with different reagents, mercuric sulphate (HgSO 4 ), potassium dichromate (K 2 Cr 2 O 7 ) and sulphuric acid (H 2 SO 4 ) silver sulphate reagent in a sequential manner.   iv) diluting the sample to a desired level and adding the reagents in a sequential manner.   v) noting down the color of the reaction mixture visually and record the color code using a color chart within 1 minute of incubation and reading optical density (O.D.) of the sample.       

     Accordingly the present invention provides a method for the preparation of COD chart useful for the estimation of COD in a sample, said method comprising the steps of:
         a) preparing standard glucose solution by dissolving glucose in distilled water at a concentration ranging between 200 mg/L to 1,00,000 mg/L with a COD concentration ranging between 213 mg/L to 1,06,700 mg/L,   b) mixing 1 mL of standard glucose solutions from step (a), individually, with three reagents, consisting of 0.02 g mercuric sulfate, 0.5 mL of 0.25 N potassium dichromate solution and 1.5 mL of sulfuric acid—silver sulfate in a sequential manner, and   c) preparing a COD color chart of different glucose concentration as shown in  FIG. 1  of accompanying drawings based on the COD concentration ranging between 213 mg/L to 1,06,700 mg/L, and which chart is useful for rough estimation of COD values by comparing the colors of the chart with the color of the samples.       

     The present invention also provides a rapid method for the estimation of COD of an effluent from domestic, industrial, municipal and other sources, said method comprising the steps of
         a) preparing a set of standard glucose solutions by dissolving glucose in distilled water at a concentration ranging between 300 mg/L to 500 mg/L, with a COD concentration of 320 mg/L to 535 mg/L,   b) mixing 1 mL of standard glucose solutions from step (a), individually, with three reagents, consisting of 0.02 g mercuric sulfate, 0.5 mL of 0.25 N potassium dichromate solution and 1.5 mL of sulfuric acid—silver sulfate in a sequential manner,   c) mixing 1 mL of a sample to be tested with 0.01 to 0.03 g mercuric sulfate per ml of a standard glucose solution, 0.5 mL of 0.25 N to 0.30 N potassium dichromate and 1.5 mL of sulfuric acid—silver sulfate reagents in a sequential manner and noting down the color and if the color of the reaction mixture turns (color code C10000) brown,   d) diluting the sample according to table 1 (a) with distilled water till a particular color range of C100 to C10000 is achieved as shown in  FIG. 1  of accompanying drawing,   e) further diluting the sample with distilled water to obtain a COD range in between 320 to 535 mg/L wherein the dilution is determined according to tables 1 (a) &amp; (b),   f) mixing 1 mL of diluted sample from step (e), individually, with three reagents, consisting of 0.02 g mercuric sulfate, 0.5 mL of 0.25 N to 0.30 N potassium dichromate solution and 1.5 mL of sulfuric acid—silver sulfate in the above sequential manner,   g) matching the color of the reaction mixture of the above sample (step f) with the COD color chart provided in  FIG. 1  of the accompanying drawing,   h) noting the optical density (OD) of the reaction mixture of standard glucose solutions (step b) and sample (step f) at 585 nm or 635 nm, against air,   i) drawing a correlation between the OD values of above sample with OD values of standard glucose solutions,   j) multiplying the OD value of sample (step h) with a correction factor of 1.2, comparing this value (A) with the OD value of standard glucose solution of COD value 320 to 535 mg/l,   k) multiplying value (A) with the compared COD value of standard Glucose solution and divided by the respective OD value of the glucose standard (B), and   l) then multiply value (B) with a dilution factor (in case of diluted sample) to obtain the COD value of the sample in terms of mg/l.       

     In yet another embodiment, the tables 1(a) and 1(b) are as follows: 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 1(a) 
               
               
                   
               
               
                 Color of the 
                   
                   
                 Expected COD 
               
               
                 reaction 
                 Required dilution 
                   
                 of unknown 
               
               
                 mixture 
                 of sample 
                 Color code 
                 sample (mg/L) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 C 10000 
                 10 
                 C1000 
                 10000 
               
               
                 C 10000 
                 100 
                 C100-C500 
                 10000-50000  
               
               
                 C 10000 
                 200 
                 C250-C500 
                 50000-100000 
               
               
                 C 10000 
                 500 
                  C200-C2000 
                 100000-1000000 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
             
           
               
                 TABLE 1(b) 
               
               
                   
               
               
                 Color of the 
                   
                 Dilution required  
               
               
                 reaction 
                 Expected  
                 to bring COD value 
               
               
                 mixture 
                 COD (mg/L) 
                 (300-500 mg/L) 
               
               
                   
               
             
             
               
                 C9000 
                 9000-9500 
                 18-31 
               
               
                 C6000 
                 6000-8500 
                 12-28 
               
               
                 C2000 
                 2000-5500 
                  4-18 
               
               
                 C1500 
                 1500-1900 
                 3-6 
               
               
                 C1200 
                 1200-1400 
                 2-5 
               
               
                 C600  
                  600-1100 
                 2-4 
               
               
                 C500  
                 500-550 
                 NIL 
               
               
                 C400  
                 400-450 
                 NIL 
               
               
                 C300  
                 300-350 
                 NIL 
               
               
                 C200  
                 200-250 
                 NIL 
               
               
                 C150  
                 100-150 
                 NIL 
               
               
                 C100  
                  00-100 
                 NIL 
               
               
                   
               
             
          
         
       
     
     In yet another embodiment, in step (d) the dilution of samples, provide dark brown reaction mixture, falling in the range of 10 to 500 for approximate cod values of 10000 mg/l and above as given in Table 1(c) and further dilution of nil to 31 is done to bring the COD in the range of 300 to 500 mg/l as given in Table 1(d). 
     In yet another embodiment, in step (e), the samples provide yellowish to blackish brown colored reaction mixture falling in the range of 100 to 9500 mg/l COD and the samples are further diluted to 31 times to obtain a diluted sample in the COD range of 300 to 500 mg/l, according to the Table 1(d). 
     In yet another embodiment, in step (d) the dilution of samples and color groups range from (A) to (G) for approximate COD values lying in the range of 100 to 9500 mg/l as given in table 1(d). 
     In yet another embodiment, tables 1(c) and 1(d) are shown below. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 1(c) 
               
               
                   
               
               
                   
                 Color code of 
                 Dilution required 
                   
                   
                   
               
               
                   
                 the reaction 
                 to bring the 
                 Color obtained 
                 Expected 
                   
               
               
                 Color of the 
                 mixture 
                 COD values in 
                 on dilution as 
                 COD of the 
                 Expected COD of 
               
               
                 reaction 
                 as per the 
                 the range of 
                 per the provided 
                 reaction 
                 unknown sample 
               
               
                 mixture 
                 provided chart 
                 100-1000 mg/l 
                 color chart 
                 mixture (mg/l) 
                 (mg/l) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Dark brown 
                 C 10000 to 
                 i) 
                 10 
                 C 1000 
                 1000 
                 10000 
               
               
                   
                 C 100000 
                 ii) 
                 100 
                 C 100-C 500 
                 100 to 500 
                 10000 to 50000 
               
               
                   
                   
                 iii) 
                 200 
                 C 250-C 500 
                 250 to 500 
                  50000 to 100000 
               
               
                   
                   
                 iv) 
                 500 
                 C 200 to C 2000 
                  200 to 2000 
                  100000 to 1000000 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
             
           
               
                 TABLE 1(d) 
               
               
                   
               
               
                   
                 Color of the 
                 Color code of the 
                 Expected COD 
                 Dilution required to bring 
               
               
                 Color 
                 reaction 
                 reaction mixture as per 
                 of the reaction 
                 the COD values in the 
               
               
                 group 
                 mixture 
                 the chart provided 
                 mixture 
                 range of 300 to 500 mg/l 
               
               
                   
               
             
             
               
                 A 
                 Yellowish 
                 C 100 to C 250 
                  1 to 250 
                 Nil 
               
               
                 B 
                 Yellowish 
                 C 300 to C 550 
                 300 to 550 
                 Nil 
               
               
                 C 
                 Greenish blue 
                  C 600 to C 1000 
                  600 to 1000 
                 2 to 4 
               
               
                 D 
                 Blue to  
                 C 1500 to C 2500 
                 1500 to 2500 
                 3 to 6 
               
               
                   
                 grayish blue 
                   
                   
                   
               
               
                 E 
                 Dirty brown 
                 C 3000 to C 5500 
                 3000 to 5500 
                  6 to 18 
               
               
                 F 
                 Cola brown 
                 C 6000 to C 8500 
                 6000 to 8500 
                 12 to 28 
               
               
                 G 
                 Blackish brown 
                 C 9000 to 9500      
                 9000 to 9500 
                 18-31 
               
               
                   
               
             
          
         
       
     
     One more embodiment of the invention provides a kit for estimation of Chemical Oxygen Demand (COD) which comprises:
         a) reagents A) HgSO 4  (solid), B) Glucose standard solutions ranging from 300 to 500 mg/L, C). K 2 Cr 2 O 7  solution (0.25 to 0.3 N), and D) H 2 SO 4 -silver sulfate reagent,   b) a glass vial,   c) a photometric cell,   d) a COD color chart as shown in  FIG. 1  of the accompanying drawing and a photometer suitable for wave lengths in the range of 585 to 635 nm.       

     One more embodiment of the present invention is a method for the preparation of reference tables 1(e) and 1(f) of COD values, useful for the estimation of COD in a sample, said method comprising the steps of:
         a) preparing standard glucose solution by dissolving glucose in distilled water at a concentration ranging between 200 mg/L to 100,000 mg/L with a COD concentration ranging between 213 mg/L to 106,700 mg/L,   b) mixing 1 mL of standard glucose solutions from step (a), individually, with three reagents, consisting of 0.02 g mercuric sulfate, 0.5 mL of 0.25 N potassium dichromate solution and 1.5 mL of sulfuric acid—silver sulfate in a sequential manner, and   c) preparing reference tables 1(e) and 1(f) for COD values of different glucose concentration based on the COD concentration ranging between 213 mg/L to 106,700 mg/L, and which tables are useful for rough estimation of COD values by comparing the colors indicated in the tables with the color of the samples.       

     In another embodiment the present invention provides the reference tables 1(e) and 1(f) are as shown below. 
     
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1(e) 
               
               
                   
               
               
                   
                 Dilution required to 
                   
                   
               
               
                 Color of the 
                 bring the COD 
                 Expected COD 
                 Expected COD 
               
               
                 reaction 
                 values in the range 
                 of the reaction 
                 of unknown 
               
               
                 mixture 
                 of 100-1000 mg/l 
                 mixture (mg/l) 
                 sample (mg/l) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Dark brown 
                 v) 
                 10 
                 1000 
                 10000 
               
               
                   
                 vi) 
                 100 
                 100 to 500 
                 10000 to 50000 
               
               
                   
                 vii) 
                 200 
                 250 to 500 
                  50000 to 100000 
               
               
                   
                 viii) 
                 500 
                  200 to 2000 
                  100000 to 1000000 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
             
           
               
                 TABLE 1(f) 
               
               
                   
               
               
                   
                   
                   
                 Dilution required to  
               
               
                   
                   
                   
                 bring the COD values 
               
               
                 Color 
                 Color of the 
                 Expected COD of 
                 in the range of 
               
               
                 group 
                 reaction mixture 
                 the reaction mixture 
                 300 to 500 mg/l 
               
               
                   
               
             
             
               
                 A 
                 Yellowish 
                  1 to 250 
                 Nil 
               
               
                 B 
                 Yellowish 
                 300 to 550 
                 Nil 
               
               
                 C 
                 Greenish blue 
                  600 to 1000 
                 2 to 4 
               
               
                 D 
                 Blue to 
                 1500 to 2500 
                 3 to 6 
               
               
                   
                 grayish blue 
                   
                   
               
               
                 E 
                 Dirty brown 
                 3000 to 5500 
                  6 to 18 
               
               
                 F 
                 Cola brown 
                 6000 to 8500 
                 12 to 28 
               
               
                 G 
                 Blackish brown 
                 9000 to 9500 
                 18-31 
               
               
                   
               
             
          
         
       
     
     In another embodiment, the present invention provides a rapid method for the estimation of COD of an effluent from domestic, industrial, municipal and other sources using reference tables as given above, said method comprising the steps of
         a) preparing a set of standard glucose solutions by dissolving glucose in distilled water at a concentration ranging between 300 mg/L to 500 mg/L, with a COD concentration of 320 mg/L to 535 mg/L,   b) mixing 1 mL of standard glucose solutions from step (a), individually, with three reagents, consisting of 0.02 g mercuric sulfate, 0.5 mL of 0.25 N potassium dichromate solution and 1.5 mL of sulfuric acid—silver sulfate in a sequential manner,   c) mixing 1 mL of a sample to be tested with 0.02 g mercuric sulfate, 0.5 mL of 0.25 N potassium dichromate and 1.5 mL of sulfuric acid—silver sulfate reagents in a sequential manner and noting down the color till the color of the reaction mixture turns brown,   d) diluting the sample as per tables 1(e) and 1(f) with distilled water till a particular color range shown in the tables is achieved,   e) further diluting the sample with distilled water to obtain a COD range in between 320 to 535 mg/L wherein the dilution is determined according to tables 1(e) and 1(f),   f) mixing 1 mL of diluted sample from step (e), individually, with three reagents, consisting of 0.02 g mercuric sulfate, 0.5 mL of 0.25 N to 0.30 N potassium dichromate solution and 1.5 mL of sulfuric acid—silver sulfate in the above sequential manner,   g) matching the color of the reaction mixture of the above sample (step f) with the COD color provided in tables 1(e) and 1(f),   h) noting the optical density (OD) of the reaction mixture of standard glucose solutions (step b) and sample (step f) at 585 nm or 635 nm, against air,   i) drawing a correlation between the OD values of above sample with OD values of standard glucose solutions,   j) multiplying the OD value of sample (step h) with a correction factor of 1.2, comparing this value (A) with the OD value of standard glucose solution of COD value 320 to 535 mg/l,   k) multiplying value (A) with the compared COD value of standard Glucose solution and divided by the respective OD value of the glucose standard (B) and   l) then multiply value (B) with a dilution factor (in case of diluted sample) to obtain the COD value of the sample in terms of mg/l.       

     In yet another embodiment, in step d, the dilution of samples provide dark brown reaction mixture falling in the range of 10 to 500 for approximate cod values of 10000 mg/l and above as given in Table 1(e) and further dilution of nil to 31 is done to bring the COD in the range of 300 to 500 mg/l as given in Table 1(f). 
     In yet another embodiment, in step (e), the samples provide yellowish to blackish brown coloured reaction mixture falling in the range of 100 to 9500 mg/l COD and the samples are further diluted to 31 times to obtain a diluted sample in the COD range of 300 to 500 mg/l, according to the Tables 1(e) and 1(f). 
     In yet another embodiment, in step (d) the dilution of samples and color groups range from (A) to (G) for approximate COD values lying in the range of 100 to 9500 mg/l as given in table 1(d). 
     In one embodiment of the present invention, the Dilution Factor is the total volume used divided by volume of the sample. 
     In another embodiment, the effluent used is selected from domestic, industrial, municipal, agricultural and other waste material sources. 
     In still another embodiment of the invention, the waste material is in the form of solid, liquid, semi-solid or viscous forms. 
     In yet another embodiment, the reagents used are HgSO 4 , glucose standard solutions, K 2 Cr 2 O 7  solution and H 2 SO 4 —silver sulfate reagent. 
     In yet another embodiment, the volume of the test sample or standard solution used ranges from 20 to 100 ml. 
     In yet another embodiment, the incubation is carried out for a period in the range between 15 seconds to 1 minute. 
     In yet another embodiment, the estimated COD is in the range between 80 to 106700 mg/L. 
     In yet another embodiment, the glucose concentration tested is ranging between 50 to 100000 mg/L. 
     In yet another embodiment, the amount of HgSO 4  used in the test samples is from 10 mg to 30 mg. 
     In yet another embodiment, the concentration of K 2 Cr 2 O 7  used in the test samples is from 0.25 Normal to 0.30 Normal. 
     In yet another embodiment, the quantity of H 2 SO 4 —silver sulfate reagent used in the test samples is 1.5 mL. 
     In yet another embodiment, the COD color chart is applicable for the COD values ranging between 100 to 10,000 mg/L. 
     In yet another embodiment, the test samples having COD value more than 10000 mg/L is diluted appropriately, 
     In yet another embodiment, the OD (optical density) of the sample is read at the wavelengths 585 and 635 nm. 
     In yet another embodiment, the optical density readings are measured for the COD values ranging from 320 to 535 mg/L. 
     In yet another embodiment, the sample is in the form of slurry. 
     In yet another embodiment, the sample used for COD estimation comprises of agricultural waste, municipal market waste, fruit and food industry waste, beverages, chemicals, microbes and animal waste etc. 
     In yet another embodiment of the present invention, the kit for estimation of Chemical Oxygen Demand (COD) which may comprise of:
         1. Reagents such as: A. HgSO 4  (solid), B. Glucose standard solutions ranging from 300 to 500 mg/L, C. K 2 Cr 2 O 7  solution (0.25 to 0.3 N), D. H 2 SO 4 —silver sulfate reagent,   2. a glass vial,   3. a photometric cell,   4. reference tables 1(e) and 1(f),   5. a photometer suitable for wave lengths in the range of 585 to 635 nm.       

     The file of this patent contains at least one drawing executed in color. Copies of this patent with color drawing(s) will be provided by the Patent &amp; Trademark Office upon request and payment of the necessary fee. 
    
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING 
         FIG. 1  shows the color code chart of COD values. 
     
    
    
     Having now generally described this invention, a further understanding can be obtained by reference to certain specific examples, which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified. 
     Example 1 
     Dissolved 0.5 and 5 g glucose in 50 mL distilled water, separately. Aliquots from the stock solutions were taken and diluted with water to achieve different concentrations in the range of 200 to 5000 (COD: 213 to 5335 mg/L) and 10000 to 100000 mg/L (COD: 10670 to 106700 mg/L), respectively. Weighed 0.02 g HgSO 4  in separate 15 mL and 50 mL test tubes. 1.0 mL of glucose sample was added to each test tube and shake well. 0.5 ml of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 1 min of incubation. The color varied with concentration. In 200 to 5000 mg/L glucose solutions, the color varied from C200 to C5000. At 5000 mg/L glucose and higher concentrations, the final color was always turbid. However, at concentration above 10000 mg/L glucose concentrations, the final color was always brown (C10000) and turbid. Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with initial COD concentration of 10000 or more, the sample needs to be diluted and its COD, re-estimated by taking the dilution factor and color of the reaction mixture into consideration. 
     
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Correlation between COD concentration and 
               
               
                 color of the reaction mixture. 
               
             
          
           
               
                 Glucose 
                 COD of Glucose 
                 Color of the 
               
               
                 Concentration 
                 the solution 
                 reaction 
               
               
                 (mg/L) 
                 (mg/L) 
                 mixture 
               
               
                   
               
             
          
           
               
                 00 
                 0.0 
                 C00  
               
               
                 (Blank) 
                   
                   
               
               
                 200 
                 213.4 
                 C200 
               
               
                 250 
                 266.7 
                 C250 
               
               
                 300 
                 320.1 
                 C300 
               
               
                 350 
                 373.4 
                 C350 
               
               
                 400 
                 426.8 
                 C400 
               
               
                 450 
                 480.1 
                 C450 
               
               
                 500 
                 533.5 
                 C500 
               
               
                 600 
                 640.2 
                 C600 
               
               
                 700 
                 746.9 
                 C700 
               
               
                 800 
                 853.6 
                 C800 
               
               
                 900 
                 960.3 
                 C900 
               
               
                 1000 
                 1067.0 
                 C100 
               
               
                 1500 
                 1600.5 
                  C1500 
               
               
                 2000 
                 2134.0 
                  C2000 
               
               
                 2500 
                 2667.5 
                  C2500 
               
               
                 3000 
                 3201.0 
                  C3000 
               
               
                 3500 
                 3734.5 
                  C3500 
               
               
                 4000 
                 4268.0 
                  C4000 
               
               
                 4500 
                 4801.5 
                  C4500 
               
               
                 5000 
                 5335.0 
                  C5000 
               
               
                 10000 
                 10670.0 
                  C10000 
               
               
                 50000 
                 53350.0 
                  C50000 
               
               
                 100000 
                 106700.0 
                   C100000 
               
               
                   
               
             
          
         
       
     
     Example 2 
     Dissolved 0.5 and 5 g glucose in 50 mL and 100 mL distilled water, respectively. Aliquots from the stock solutions were taken and diluted with water to achieve different concentrations in the range of 50 to 5000 (COD: 80 to 5335 mg/L) and 5500 to 100000 mg/L (COD: 5868 to 106700 mg/L), respectively. Weighed 0.02 g HgSO 4  in separate 15 mL and 50 mL test tubes. 1.0 mL of glucose sample was added to each test tube and shake well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 1 min of incubation. The color varied with concentration. In 50 to 9500 mg/L glucose solutions, the color varied from C50 to C9500. At 5500 mg/L glucose and higher concentrations, the final color was always turbid. However, at concentration above 10000 mg/L glucose concentrations, the final color was always C10000. Hence, for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with initial COD concentration of 10000 or more, the sample needs to be diluted and its COD, re-estimated by taking the dilution factor and color of the reaction mixture into consideration. 
     
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Correlation between COD concentration 
               
               
                 and color of the reaction mixture. 
               
             
          
           
               
                   
                 COD of 
                   
               
               
                 Glucose 
                 Glucose 
                 Color of the 
               
               
                 Concentration 
                 solution 
                 reaction 
               
               
                 (mg/L) 
                 (mg/L) 
                 mixture 
               
               
                   
               
             
          
           
               
                 00 
                 0.0 
                 C00  
               
               
                 (Blank) 
                   
                   
               
               
                 50 
                 80.3 
                 C50  
               
               
                 100 
                 106.7 
                 C100  
               
               
                 150 
                 241.0 
                 C150  
               
               
                 200 
                 213.4 
                 C200  
               
               
                 250 
                 266.7 
                 C250  
               
               
                 300 
                 320.1 
                 C300  
               
               
                 350 
                 373.4 
                 C350  
               
               
                 400 
                 426.8 
                 C400  
               
               
                 450 
                 480.1 
                 C450  
               
               
                 500 
                 533.5 
                 C500  
               
               
                 550 
                 583.8 
                 C550  
               
               
                 600 
                 640.2 
                 C600  
               
               
                 650 
                 693.5 
                 C650  
               
               
                 700 
                 746.9 
                 C700  
               
               
                 750 
                 800.2 
                 C750  
               
               
                 800 
                 853.6 
                 C800  
               
               
                 850 
                 906.9 
                 C850  
               
               
                 900 
                 960.3 
                 C900  
               
               
                 950 
                 1013.6 
                 C950  
               
               
                 1000 
                 1067.0 
                 C1000 
               
               
                 1100 
                 1173.7 
                 C1100 
               
               
                 1200 
                 1280.4 
                 C1200 
               
               
                 1300 
                 1387.1 
                 C1300 
               
               
                 1400 
                 1493.8 
                 C1400 
               
               
                 1500 
                 1600.5 
                 C1500 
               
               
                 1600 
                 1707.2 
                 C1600 
               
               
                 1700 
                 1813.9 
                 C1700 
               
               
                 1800 
                 1920.6 
                 C1800 
               
               
                 1900 
                 2027.3 
                 C1900 
               
               
                 2000 
                 2134.0 
                 C2000 
               
               
                 2500 
                 2667.5 
                 C2500 
               
               
                 3000 
                 3201.0 
                 C3000 
               
               
                 3500 
                 3734.5 
                 C3500 
               
               
                 4000 
                 4268.0 
                 C4000 
               
               
                 4500 
                 4801.5 
                 C4500 
               
               
                 5000 
                 5335.0 
                 C5000 
               
               
                 5500 
                 5868.5 
                 C5500 
               
               
                 6000 
                 6402.0 
                 C6000 
               
               
                 6500 
                 6935.5 
                 C6500 
               
               
                 7000 
                 7469.0 
                 C7000 
               
               
                 7500 
                 8002.5 
                 C7500 
               
               
                 8000 
                 8536.0 
                 C8000 
               
               
                 8500 
                 9069.5 
                 C8500 
               
               
                 9000 
                 9603.0 
                 C9000 
               
               
                 9500 
                 10136.5 
                 C9500 
               
               
                 10000 
                 10670.0 
                  C10000 
               
               
                 15000 
                 16005.0 
                  C15000 
               
               
                 20000 
                 21340.0 
                  C20000 
               
               
                 30000 
                 32010.0 
                  C30000 
               
               
                 40000 
                 42680.0 
                  C40000 
               
               
                 50000 
                 53350.0 
                  C50000 
               
               
                 100000 
                 106700.0 
                  C100000 
               
               
                   
               
             
          
         
       
     
     Example 3 
     Dissolved 0.5 g glucose in 50 ml distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different concentrations in the range of 100 to 2000 mg/L (COD: 106.7 to 2134 mg/L). Weighed 0.02 g HgSO 4  in separate 15 mL and 25 mL test tubes. 1.0 ml of glucose sample was added to each test tube and shake well. 0.5 ml of K 2 Cr 2 O 7  was added to each sample. 1.5 ml H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 1 min of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. The color varied with concentration. In 100 to 2000 mg/L glucose solutions, the color varied from C100 to C2000. At 100 to 800 mg/L glucose concentrations, OD 585 varied from 0.104 to 0.307 and OD 635 varied from 0.092 to 0.276. In the COD range of 106.7 to 640.2 mg/L the OD 585 and OD 635 there was an incremental difference of 0.030 and 0.027 for each 106.7 mg/L COD increase, respectively. At different wavelengths, OD became stable at 1000 mg/L glucose and higher concentrations. Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with initial OD concentration of 100 to 640 mg/L, OD 585 or OD 635 can be recorded for obtaining more values that are precise. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                 COD of 
                 Color 
                 OD 585 nm 
                 OD 635 nm 
               
               
                 Glucose 
                 Glucose 
                 of the 
                 of the 
                 of the 
               
               
                 Concentration 
                 solution 
                 reaction 
                 reaction 
                 reaction 
               
               
                 (mg/L) 
                 (mg/L) 
                 mixture 
                 mixture 
                 mixture 
               
               
                   
               
             
          
           
               
                 100 
                 106.7 
                 C100  
                 0.104 
                 0.092 
               
               
                 200 
                 213.4 
                 C200  
                 0.133 
                 0.117 
               
               
                 300 
                 320.1 
                 C300  
                 0.164 
                 0.143 
               
               
                 400 
                 426.8 
                 C400  
                 0.196 
                 0.165 
               
               
                 500 
                 533.5 
                 C500  
                 0.222 
                 0.193 
               
               
                 600 
                 640.2 
                 C600  
                 0.252 
                 0.226 
               
               
                 800 
                 853.6 
                 C800  
                 0.307 
                 0.276 
               
               
                 1000 
                 1067.0 
                 C1000 
                 0.362 
                 0.332 
               
               
                 1200 
                 1280.4 
                 C1200 
                 0.347 
                 0.316 
               
               
                 1400 
                 1493.8 
                 C1400 
                 0.351 
                 0.323 
               
               
                 1600 
                 1707.2 
                 C1600 
                 0.354 
                 0.354 
               
               
                 1800 
                 1920.6 
                 C1800 
                 0.344 
                 0.328 
               
               
                 2000 
                 2134.0 
                 C2000 
                 0.358 
                 0.343 
               
               
                   
               
             
          
         
       
     
     Example 4 
     Dissolved 1 g glucose in 100 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different concentrations in the range of 100 to 2000 mg/L (COD: 106.7 to 2134 mg/L). Weighed 0.02 g HgSO 4  in separate 15 mL and 25 mL test tubes. 1.0 mL of glucose sample was added to each test tube and shake well. 0.5 ml of K 2 Cr 2 O 7  was added to each sample. 1.5 ml H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 30 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. The color varied with concentration. In 100 to 2000 mg/L glucose solutions, the color varied from C100 to C2000. At 100 to 1000 mg/L glucose concentrations, OD 585 varied from 0.109 to 0.347 and OD 635 varied from 0.096 to 0.317. In the COD range of 106.7 to 640.2 mg/L the OD 585 and OD 635 there was an incremental difference of 0.027 and 0.026 for each 106.7 mg/L COD increase, respectively. At different wavelengths, OD became stable at 1000 mg/L glucose and higher concentrations. Hence, for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with initial COD concentration of 100 to 640 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                 COD of 
                 Color 
                 OD 585 nm 
                 OD 635 nm 
               
               
                 Glucose 
                 Glucose 
                 of the 
                 of the 
                 of the 
               
               
                 Concentration 
                 solution 
                 reaction 
                 reaction 
                 reaction 
               
               
                 (mg/L) 
                 (mg/L) 
                 mixture 
                 mixture 
                 mixture 
               
               
                   
               
             
          
           
               
                 100 
                 106.7 
                 C100  
                 0.109 
                 0.096 
               
               
                 200 
                 213.4 
                 C200  
                 0.132 
                 0.116 
               
               
                 300 
                 320.1 
                 C300  
                 0.161 
                 0.142 
               
               
                 400 
                 426.8 
                 C400  
                 0.193 
                 0.164 
               
               
                 500 
                 533.5 
                 C500  
                 0.222 
                 0.195 
               
               
                 600 
                 640.2 
                 C600  
                 0.246 
                 0.226 
               
               
                 800 
                 853.6 
                 C800  
                 0.300 
                 0.274 
               
               
                 1000 
                 1067.0 
                 C1000 
                 0.347 
                 0.317 
               
               
                 1200 
                 1280.4 
                 C1200 
                 0.350 
                 0.321 
               
               
                 1400 
                 1493.8 
                 C1400 
                 0.341 
                 0.326 
               
               
                 1600 
                 1707.2 
                 C1600 
                 0.352 
                 0.332 
               
               
                 1800 
                 1920.6 
                 C1800 
                 0.354 
                 0.331 
               
               
                 2000 
                 2134.0 
                 C2000 
                 0.354 
                 0.349 
               
               
                   
               
             
          
         
       
     
     Example 5 
     Dissolved 0.25 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different concentrations in the range of 100 to 500 mg/L (COD: 106.7 to 533.5 mg/L). Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose sample was added to each test tube and shake well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 30 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. The color varied with concentration. In 100 to 500 mg/L glucose solutions, the color varied from C100 to C500. At 100 to 500 mg/L glucose concentrations, OD 585 varied from 0.106 to 0.223 and OD 635 varied from 0.089 to 0.199. In the COD range of 106.7 to 533.5 mg/L the OD 585 and OD 635 there was an incremental difference of 0.029 and 0.027 for each 106.7 mg/L COD increase, respectively. Hence, for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with initial COD concentration of 106.7 to 533.5 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                 COD of 
                 Color 
                 OD 585 nm 
                 OD 635 nm 
               
               
                 Glucose 
                 Glucose 
                 of the 
                 of the 
                 of the 
               
               
                 Concentration 
                 solution 
                 reaction 
                 reaction 
                 reaction 
               
               
                 (mg/L) 
                 (mg/L) 
                 mixture 
                 mixture 
                 mixture 
               
               
                   
               
               
                 100 
                 106.7 
                 C100 
                 0.106 
                 0.089 
               
               
                 200 
                 213.4 
                 C200 
                 0.133 
                 0.116 
               
               
                 300 
                 320.1 
                 C300 
                 0.162 
                 0.144 
               
               
                 400 
                 426.8 
                 C400 
                 0.192 
                 0.166 
               
               
                 500 
                 533.5 
                 C500 
                 0.223 
                 0.199 
               
               
                   
               
             
          
         
       
     
     Example 6 
     Dissolved 0.2 g glucose in 50 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different concentrations in the range of 100 to 500 mg/L (COD: 106.7 to 533.5 mg/L). Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 ml of glucose sample was added to each test tube and shake well. 0.5 ml of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. The color varied with concentration. In 100 to 500 mg/L glucose solutions, the color varied from C100 to C500. At 100 to 500 mg/L glucose concentrations, OD 585 varied from 0.104 to 0.225 and OD 635 varied from 0.089 to 0.196. In the COD range of 106.7 to 533.5 mg/L the OD 585 and OD 635 there was an incremental difference of 0.030 and 0.028 for each 106.7 mg/L COD increase, respectively. Hence, for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with initial COD concentration of 106.7 to 533.5 mg/L, OD 585 or OD 635 can be recorded for obtaining more accurate values. 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction  
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                 COD of 
                 Color 
                 OD 585 nm 
                 OD 635 nm 
               
               
                 Glucose 
                 Glucose 
                 of the 
                 of the 
                 of the 
               
               
                 Concentration 
                 solution 
                 reaction 
                 reaction 
                 reaction 
               
               
                 (mg/L) 
                 (mg/L) 
                 mixture 
                 mixture 
                 mixture 
               
               
                   
               
               
                 100 
                 106.7 
                 C100 
                 0.104 
                 0.089 
               
               
                 200 
                 213.4 
                 C200 
                 0.132 
                 0.115 
               
               
                 300 
                 320.1 
                 C300 
                 0.164 
                 0.145 
               
               
                 400 
                 426.8 
                 C400 
                 0.196 
                 0.165 
               
               
                 500 
                 533.5 
                 C500 
                 0.225 
                 0.196 
               
               
                   
               
             
          
         
       
     
     Example 7 
     Dissolved 0.3 g glucose in 50 ml distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different concentrations in the range of 300 to 500 mg/L (COD: 320.1 to 533.5 mg/L). Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 ml of glucose sample was added to each test tube and shake well 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 against air. The color varied with concentration. In 300 to 500 mg/L glucose solutions, the color varied from C300 to C500. At 300 to 500 mg/L glucose concentrations, OD 585 varied on an average from 0.158 to 0.210. In the COD range of 320.1 to 533.5 mg/L the OD 585 there was an incremental difference of 0.026 for each 106.7 mg/L COD increase. Hence, for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with initial COD concentration of 320.1 to 533.5 mg/L, OD 585 can be recorded for obtaining values that are more precise. 
     
       
         
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 7 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at 585 nm. 
               
             
          
           
               
                   
                   
                   
                 COD of 
                 Color 
                 OD 585 nm 
               
               
                   
                   
                 Glucose 
                 Glucose 
                 of the 
                 of the 
               
               
                   
                 S. 
                 Concentration 
                 solution 
                 reaction 
                 reaction 
               
               
                   
                 No. 
                 (mg/L) 
                 (mg/L) 
                 mixture 
                 mixture 
               
               
                   
                   
               
               
                   
                 1. 
                 300 
                 320.1 
                 C300 
                 0.154 
               
               
                   
                 2. 
                 300 
                 320.1 
                 C300 
                 0.168 
               
               
                   
                 3. 
                 300 
                 320.1 
                 C300 
                 0.162 
               
               
                   
                 4. 
                 300 
                 320.1 
                 C300 
                 0.155 
               
               
                   
                 5. 
                 300 
                 320.1 
                 C300 
                 0.153 
               
               
                   
                 6. 
                 300 
                 320.1 
                 C300 
                 0.158 
               
               
                   
                 7. 
                 300 
                 320.1 
                 C300 
                 0.157 
               
               
                   
                 1. 
                 400 
                 426.8 
                 C400 
                 0.178 
               
               
                   
                 2. 
                 400 
                 426.8 
                 C400 
                 0.207 
               
               
                   
                 3. 
                 400 
                 426.8 
                 C400 
                 0.189 
               
               
                   
                 4. 
                 400 
                 426.8 
                 C400 
                 0.183 
               
               
                   
                 5. 
                 400 
                 426.8 
                 C400 
                 0.181 
               
               
                   
                 6. 
                 400 
                 426.8 
                 C400 
                 0.185 
               
               
                   
                 7. 
                 400 
                 426.8 
                 C400 
                 0.186 
               
               
                   
                 1. 
                 500 
                 533.5 
                 C500 
                 0.193 
               
               
                   
                 2. 
                 500 
                 533.5 
                 C500 
                 0.234 
               
               
                   
                 3. 
                 500 
                 533.5 
                 C500 
                 0.207 
               
               
                   
                 4. 
                 500 
                 533.5 
                 C500 
                 0.215 
               
               
                   
                 5. 
                 500 
                 533.5 
                 C500 
                 0.207 
               
               
                   
                 6. 
                 500 
                 533.5 
                 C500 
                 0.208 
               
               
                   
                 7. 
                 500 
                 533.5 
                 C500 
                 0.210 
               
               
                   
                   
               
             
          
         
       
     
     Example 8 
     Dissolved 0.5 g glucose in 100 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 533 mg/L. A 20 mL sample of anaerobically digested damaged wheat grain slurry initially inoculated with  Aspergillus niger  for 10 days was taken. COD of the sample was estimated to be 52300 mg/L. (By Merck method and read on photometer.) Based on the estimated COD value, diluted samples were prepared in water to achieve a final COD in the range of 415 to 520 mg/L. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. The color varied with concentration. In 320 to 533 mg/L glucose solutions, the color varied from C300 to C550. At 320 to 533 mg/L glucose concentrations, average OD 585 varied from 0.152 to 0.192 and OD 635 varied from 0.141 to 0.183. In the COD range of 320.1 to 533.5 mg/L the OD 585 and OD 635 there was an incremental difference of 0.026 and 0.024 for each 106.7 mg/L COD increase, respectively. On the other hand, color of the final sample reaction mixture varied from C400 to C500. 
     At 415.5 to 519.3 mg/L COD concentrations of the sample, average OD 585 varied from 0.145 to 0.169 and OD 635 varied from 0.129 to 0.148. In this COD range, there was an incremental difference of 0.024 and 0.020 for each 103.8 mg/L COD increase at OD 585 and OD 635, respectively. 
     Hence, for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 415.5 to 519.3 mg/L, OD 585 or OD 635 can be recorded for obtaining values that is more precise. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 8 
               
             
             
               
                   
               
               
                 Correlation between COD. concentration, color of the reaction mixture 
               
               
                 and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                 Color of the 
                 OD of the reaction mixture 
                   
               
             
          
           
               
                   
                 COD (mg/L) 
                 reaction mixture 
                 585 nm 
                 635 nm 
               
               
                   
               
             
          
           
               
                 Glucose: 
               
             
          
           
               
                   
                 320 
                 C300 
                 0.154 
                 0.142 
               
               
                   
                   
                 C300 
                 0.150 
                 0.139 
               
               
                   
                   
                 C300 
                 0.153 
                 0.142 
               
               
                   
                 426 
                 C400 
                 0.178 
                 0.166 
               
               
                   
                   
                 C400 
                 0.175 
                 0.162 
               
               
                   
                   
                 C400 
                 0.181 
                 0.169 
               
               
                   
                 533 
                 C550 
                 0.192 
                 0.183 
               
               
                   
                   
                 C550 
                 0.190 
                 0.180 
               
               
                   
                   
                 C550 
                 0.194 
                 0.185 
               
             
          
           
               
                 Sample: Damaged wheat grain slurry 
               
             
          
           
               
                   
                 415.5 
                 C400 
                 0.142 
                 0.128 
               
               
                   
                   
                 C400 
                 0.152 
                 0.132 
               
               
                   
                   
                 C400 
                 0.141 
                 0.128 
               
               
                   
                 467.9 
                 C450 
                 0.146 
                 0.128 
               
               
                   
                   
                 C450 
                 0.149 
                 0.135 
               
               
                   
                   
                 C450 
                 0.147 
                 0.128 
               
               
                   
                 519.3 
                 C500 
                 0.180 
                 0.161 
               
               
                   
                   
                 C500 
                 0.166 
                 0.140 
               
               
                   
                   
                 C500 
                 0.162 
                 0.142 
               
               
                   
               
             
          
         
       
     
     Example 9 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 533 mg/L. A 30 mL sample of anaerobically digested damaged wheat grain slurry initially inoculated with  Bacillus licheniformis  was taken. COD of the sample was estimated to be 54700 mg/L. (By Merck method and read on photometer.) Based on the estimated COD value, diluted samples were prepared in water to achieve a final COD in the range of 300 to 500 mg/L. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. The color varied with concentration. In 320 to 533 mg/L glucose solutions, the color varied from C300 to C550. At 320 to 533 mg/L glucose concentrations, average OD 585 varied from 0.168 to 0.234 and OD 635 varied from 0.151 to 0.213. In the COD range of 320.1 to 533.5 mg/L the OD 585 and OD 635 there was an incremental difference of 0.033 for each 106.7 mg/L COD increase. On the other hand, color of the final sample reaction mixture varied from C300 to C550. At 300 to 500 mg/L COD concentrations of the sample, average OD 585 varied from 0.136 to 0.175 and OD 635 varied from 0.123 to 0.156. In this COD range, there was an incremental difference of 0.020 and 0.017 for each 100 mg/L COD increase at OD 585 and OD 635, respectively. 
     Hence, for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining values that is more precise. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 9 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction mixture 
               
               
                 and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                 Color of the 
                 OD of the reaction mixture 
                   
               
             
          
           
               
                   
                 COD (mg/L) 
                 reaction mixture 
                 585 nm 
                 635 nm 
               
               
                   
               
             
          
           
               
                 Glucose: 
               
             
          
           
               
                   
                 320 
                 C300 
                 0.164 
                 0.146 
               
               
                   
                   
                 C300 
                 0.167 
                 0.152 
               
               
                   
                   
                 C300 
                 0.172 
                 0.154 
               
               
                   
                 426 
                 C400 
                 0.198 
                 0.182 
               
               
                   
                   
                 C400 
                 0.214 
                 0.194 
               
               
                   
                   
                 C400 
                 0.209 
                 0.193 
               
               
                   
                 533 
                 C550 
                 0.235 
                 0.212 
               
               
                   
                   
                 C550 
                 0.236 
                 0.217 
               
               
                   
                   
                 C550 
                 0.231 
                 0.211 
               
             
          
           
               
                 Sample: Damaged wheat grain slurry 
               
             
          
           
               
                   
                 300.7 
                 C300 
                 0.140 
                 0.129 
               
               
                   
                   
                 C300 
                 0.135 
                 0.121 
               
               
                   
                   
                 C300 
                 0.134 
                 0.121 
               
               
                   
                 411.6 
                 C400 
                 0.158 
                 0.146 
               
               
                   
                   
                 C400 
                 0.156 
                 0.140 
               
               
                   
                   
                 C400 
                 0.157 
                 0.141 
               
               
                   
                 500.6 
                 C500 
                 0.174 
                 0.155 
               
               
                   
                   
                 C500 
                 0.175 
                 0.160 
               
               
                   
                   
                 C500 
                 0.175 
                 0.155 
               
               
                   
               
             
          
         
       
     
     Example 10 
     Dissolved 0.2-g glucose in 50 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 533 mg/L. A 25-mL sample of anaerobically digested damaged wheat grain slurry was taken. COD of the sample was estimated to be 61300 mg/L. (By Merck method and read on photometer.) Based on the estimated COD value, diluted samples were prepared in water to achieve a final COD in the range of 335 to 505 mg/L. Weighed 0.02 g HgSO 4  in separate 15-mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and recorded spectrophotometrically at 585 and 635 nm against air. The color varied with concentration. In 320 to 533 mg/L glucose solutions, the color varied from C300 to C550. At 320 to 533 mg/L glucose concentrations, average OD 585 varied from 0.162 to 0.207 and OD 635 varied from 0.145 to 0.186. In the COD range of 320.1 to 533.5 mg/L, the OD 585 and OD 635 there was an incremental difference of 0.023 and 0.025 for each 106.7 mg/L COD increase, respectively. On the other hand, color of the final sample reaction mixture varied from C350 to C500. 
     At 335 to 505 mg/L COD concentrations of the sample, average OD 585 varied from 0.132 to 0.169 and OD 635 varied from 0.116 to 0.151. In this COD range, there was an incremental difference of 0.019 and 0.022 for each 85 mg/L COD increase at OD 585 and OD 635, respectively. 
     Hence, for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 335 to 505 mg/L, OD 585 or OD 635 can be recorded for obtaining values that is more precise. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 10 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction mixture 
               
               
                 and their OD at different wavelengths. 
               
             
          
           
               
                   
                   
                 Color of the 
                 OD of the reaction mixture 
                   
               
             
          
           
               
                   
                 COD (mg/L) 
                 reaction mixture 
                 585 nm 
                 635 nm 
               
               
                   
               
             
          
           
               
                 Glucose: 
               
             
          
           
               
                   
                 320 
                 C300 
                 0.160 
                 0.143 
               
               
                   
                   
                 C300 
                 0.164 
                 0.147 
               
               
                   
                   
                 C300 
                 0.162 
                 0.145 
               
               
                   
                 426 
                 C400 
                 0.190 
                 0.184 
               
               
                   
                   
                 C400 
                 0.191 
                 0.176 
               
               
                   
                   
                 C400 
                 0.187 
                 0.168 
               
               
                   
                 533 
                 C550 
                 0.207 
                 0.190 
               
               
                   
                   
                 C550 
                 0.206 
                 0.184 
               
               
                   
                   
                 C550 
                 0.207 
                 0.185 
               
             
          
           
               
                 Sample: Damaged wheat grain slurry 
               
             
          
           
               
                   
                 337.1 
                 C350 
                 0.128 
                 0.112 
               
               
                   
                   
                 C350 
                 0.134 
                 0.119 
               
               
                   
                   
                 C350 
                 0.135 
                 0.117 
               
               
                   
                 421.3 
                 C400 
                 0.153 
                 0.135 
               
               
                   
                   
                 C400 
                 0.151 
                 0.134 
               
               
                   
                   
                 C400 
                 0.155 
                 0.137 
               
               
                   
                 504.6 
                 C500 
                 0.168 
                 0.149 
               
               
                   
                   
                 C500 
                 0.169 
                 0.149 
               
               
                   
                   
                 C500 
                 0.169 
                 0.154 
               
               
                   
               
             
          
         
       
     
     Example 11 
     Dissolved 0.1 g glucose in 50 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 533 mg/L. A 40-mL sample of anaerobically digested damaged wheat grain slurry initially treated with  Aspergillus niqer  for 10 days and inoculated with  Bacillus subtilis  was taken. COD of the sample was estimated to be 6600 mg/L. (By Merck method and read on photometer.) Based on the estimated COD value, diluted samples were prepared in water to achieve a final COD in the range of 330 to 530 mg/L. Weighed 0.02 g HgSO 4  in separate 15-mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulfate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and recorded spectrophotometrically at 585 and 635 nm against air. The color varied with concentration. In 320 to 533 mg/L glucose solutions, the color varied from C300 to C550. At 320 to 533 mg/L glucose concentrations, average OD 585 varied from 0.155 to 0.215 and OD 635 varied from 0.144 to 0.194. In the COD range of 320.1 to 533.5 mg/L, the OD 585 and OD 635 there was an incremental difference of 0.030 and 0.025 for each 106.7-mg/L COD increase, respectively. On the other hand, color of the final sample reaction mixture varied from C350 to C550. 
     At 330 to 530 mg/L COD concentrations of the sample, average OD 585 varied from 0.137 to 0.174 and OD 635 varied from 0.121 to 0.153. In this COD range, there was an incremental difference of 0.019 and 0.016 for each 100-mg/L COD increase at OD 585 and OD 635, respectively. 
     Hence, for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 330 to 530 mg/L, OD 585 or OD 635 can be recorded for obtaining values that is more precise. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 11 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction mixture 
               
               
                 and their OD at different wavelengths. 
               
             
          
           
               
                   
                   
                 Color of the 
                 OD of the reaction mixture 
                   
               
             
          
           
               
                   
                 COD (mg/L) 
                 reaction mixture 
                 585 nm 
                 635 nm 
               
               
                   
               
             
          
           
               
                 Glucose: 
               
             
          
           
               
                   
                 320 
                 C300 
                 0.154 
                 0.143 
               
               
                   
                   
                 C300 
                 0.155 
                 0.142 
               
               
                   
                   
                 C300 
                 0.157 
                 0.146 
               
               
                   
                 426 
                 C400 
                 0.182 
                 0.170 
               
               
                   
                   
                 C400 
                 0.182 
                 0.168 
               
               
                   
                   
                 C400 
                 0.184 
                 0.170 
               
               
                   
                 533 
                 C550 
                 0.206 
                 0.187 
               
               
                   
                   
                 C550 
                 0.208 
                 0.190 
               
               
                   
                   
                 C550 
                 0.230 
                 0.205 
               
             
          
           
               
                 Sample: Damaged wheat grain slurry 
               
             
          
           
               
                   
                 331 
                 C350 
                 0.134 
                 0.118 
               
               
                   
                   
                 C350 
                 0.138 
                 0.126 
               
               
                   
                   
                 C350 
                 0.138 
                 0.120 
               
               
                   
                 429 
                 C400 
                 0.157 
                 0.139 
               
               
                   
                   
                 C400 
                 0.153 
                 0.135 
               
               
                   
                   
                 C400 
                 0.154 
                 0.134 
               
               
                   
                 529 
                 C500 
                 0.172 
                 0.152 
               
               
                   
                   
                 C500 
                 0.171 
                 0.151 
               
               
                   
                   
                 C500 
                 0.178 
                 0.156 
               
               
                   
               
             
          
         
       
     
     Example 12 
     Dissolved 0.2 g glucose in 50 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 533 mg/L. A 30 mL sample of partially digested vegetable waste slurry was taken. COD of the sample was estimated to be 9640 mg/L (By Merck method and read on photometer). Based on the estimated COD value, diluted samples were prepared in water to achieve a final COD in the range of 290 to 480 mg/L. Weighed 0.02 g HgSO 4  in separate 15-mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulfate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. The color varied with concentration. In 320 to 533 mg/L glucose solutions, the color varied from C300 to C550. At 320 to 533 mg/L glucose concentrations, average OD 585 varied from 0.153 to 0.207 and OD 635 varied from 0.142 to 0.188. In the COD range of 320.1 to 533.5 mg/L the OD 585 and OD 635 there was an incremental difference of 0.027 and 0.023 for each 106.7 mg/L COD increase, respectively. On the other hand, color of the final sample reaction mixture varied from C300 to C500. 
     At 290 to 480 mg/L COD concentrations of the sample, average OD 585 varied from 0.138 to 0.157 and OD 635 varied from 0.123 to 0.141. In this COD range, there was an incremental difference of 0.009 for each 95 mg/L COD increase at OD 585 and OD 635. 
     Hence, for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 290 to 480 mg/L, OD 585 or OD 635 can be recorded for obtaining values that is more accurate. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 12 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction mixture 
               
               
                 and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                 Color of the 
                 OD of the reaction mixture 
                   
               
             
          
           
               
                   
                 COD (mg/L) 
                 reaction mixture 
                 585 nm 
                 635 nm 
               
               
                   
               
             
          
           
               
                 Glucose: 
               
             
          
           
               
                   
                 320 
                 C300 
                 0.152 
                 0.142 
               
               
                   
                   
                 C300 
                 0.156 
                 0.145 
               
               
                   
                   
                 C300 
                 0.151 
                 0.139 
               
               
                   
                 426 
                 C400 
                 0.181 
                 0.169 
               
               
                   
                   
                 C400 
                 0.183 
                 0.170 
               
               
                   
                   
                 C400 
                 0.180 
                 0.168 
               
               
                   
                 533 
                 C550 
                 0.205 
                 0.186 
               
               
                   
                   
                 C550 
                 0.212 
                 0.194 
               
               
                   
                   
                 C550 
                 0.204 
                 0.184 
               
             
          
           
               
                 Sample: Vegetable waste slurry 
               
             
          
           
               
                   
                 290 
                 C300 
                 0.140 
                 0.123 
               
               
                   
                   
                 C300 
                 0.132 
                 0.120 
               
               
                   
                   
                 C300 
                 0.141 
                 0.127 
               
               
                   
                 386 
                 C400 
                 0.158 
                 0.143 
               
               
                   
                   
                 C400 
                 0.151 
                 0.140 
               
               
                   
                   
                 C400 
                 0.144 
                 0.128 
               
               
                   
                 482 
                 C500 
                 0.162 
                 0.146 
               
               
                   
                   
                 C500 
                 0.156 
                 0.141 
               
               
                   
                   
                 C500 
                 0.153 
                 0.137 
               
               
                   
               
             
          
         
       
     
     Example 13 
     Dissolved 0.25 g glucose in 50 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 533 mg/L. A 50 mL sample of partially digested vegetable waste slurry was mixed with anaerobically digested damaged wheat grain slurry. COD of the sample was estimated to be 9400 mg/L (By Merck method and read on photometer). Based on the estimated COD value, diluted samples were prepared in water to achieve a final COD in the range of 297 to 533 mg/L. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. The color varied with concentration. In 320 to 533 mg/L glucose solutions, the color varied from C300 to C500. At 320 to 533 mg/L glucose concentrations, average OD 585 varied from 0.158 to 0.208 and OD 635 varied from 0.138 to 0.187. In the COD range of 320.1 to 533.5 mg/L the OD 585 and OD 635 there was an incremental difference of 0.025 and 0.025 for each 106.7 mg/L COD increase, respectively. On the other hand, color of the final sample reaction mixture varied from C300 to C500. 
     At 297 to 533 mg/L COD concentrations of the sample, average OD 585 varied from 0.132 to 0.179 and OD 635 varied from 0.118 to 0.162. In this COD range, there was an incremental difference of 0.023 and 0.027 for each 118 mg/L COD increase at OD 585 and OD 635, respectively. 
     Hence, for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 297 to 533 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 13 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction mixture 
               
               
                 and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                 Color of the 
                 OD of the reaction mixture 
                   
               
             
          
           
               
                   
                 COD (mg/L) 
                 reaction mixture 
                 585 nm 
                 635 nm 
               
               
                   
               
             
          
           
               
                 Glucose: 
               
             
          
           
               
                   
                 320 
                 C300 
                 0.167 
                 0.148 
               
               
                   
                   
                 C300 
                 0.154 
                 0.135 
               
               
                   
                   
                 C300 
                 0.152 
                 0.131 
               
               
                   
                 426 
                 C400 
                 0.188 
                 0.167 
               
               
                   
                   
                 C400 
                 0.185 
                 0.162 
               
               
                   
                   
                 C400 
                 0.181 
                 0.159 
               
               
                   
                 533 
                 C550 
                 0.215 
                 0.195 
               
               
                   
                   
                 C550 
                 0.206 
                 0.184 
               
               
                   
                   
                 C550 
                 0.202 
                 0.181 
               
             
          
           
               
                 Sample: Vegetable waste slurry + Damaged wheat grain slurry 
               
             
          
           
               
                   
                 297 
                 C300 
                 0.126 
                 0.111 
               
               
                   
                   
                 C300 
                 0.138 
                 0.124 
               
               
                   
                   
                 C300 
                 0.133 
                 0.118 
               
               
                   
                 445 
                 C450 
                 0.168 
                 0.152 
               
               
                   
                   
                 C450 
                 0.164 
                 0.148 
               
               
                   
                   
                 C450 
                 0.168 
                 0.152 
               
               
                   
                 533 
                 C550 
                 0.188 
                 0.169 
               
               
                   
                   
                 C550 
                 0.180 
                 0.163 
               
               
                   
                   
                 C550 
                 0.169 
                 0.153 
               
               
                   
               
             
          
         
       
     
     Example 14 
     Dissolved 0.15 g glucose in 50 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 533 mg/L. A 30 mL sample of apple pomace soaked for 1 day was taken. COD of the sample was estimated to be 51700 mg/L (By Merck method and read on photometer). Based on the estimated COD value, diluted samples were prepared in water to achieve a final COD in the range of 310 to 517 mg/L. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 ml of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. The color varied with concentration. In 320 to 533 mg/L glucose solutions, the color varied from C300 to C550. At 320 to 533 mg/L glucose concentrations, average OD 585 varied from 0.157 to 0.210 and OD 635 varied from 0.142 to 0.189. In the COD range of 320.1 to 533.5 mg/L the OD 585 and OD 635 there was an incremental difference of 0.026 and 0.024 for each 106.7 mg/L COD increase, respectively. On the other hand, color of the final sample reaction mixture varied from C300 to C500. 
     At 310 to 517 mg/L COD concentrations of the sample, average OD 585 varied from 0.141 to 0.186 and OD 635 varied from 0.126 to 0.167. In this COD range, there was an incremental difference of 0.022 and 0.020 for each 104 mg/L COD increase at OD 585 and OD 635, respectively. 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 310 to 517 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 14 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction mixture 
               
               
                 and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                 Color of the 
                 OD of the reaction mixture 
                   
               
             
          
           
               
                   
                 COD (mg/L) 
                 reaction mixture 
                 585 nm 
                 635 nm 
               
               
                   
               
             
          
           
               
                 Glucose: 
               
             
          
           
               
                   
                 320 
                 C300 
                 0.157 
                 0.142 
               
               
                   
                   
                 C300 
                 0.154 
                 0.139 
               
               
                   
                   
                 C300 
                 0.159 
                 0.146 
               
               
                   
                 426 
                 C400 
                 0.186 
                 0.168 
               
               
                   
                   
                 C400 
                 0.185 
                 0.162 
               
               
                   
                   
                 C400 
                 0.187 
                 0.170 
               
               
                   
                 533 
                 C550 
                 0.216 
                 0.196 
               
               
                   
                   
                 C550 
                 0.209 
                 0.188 
               
               
                   
                   
                 C550 
                 0.207 
                 0.183 
               
             
          
           
               
                 Sample: Apple pomace 
               
             
          
           
               
                   
                 310 
                 C300 
                 0.140 
                 0.126 
               
               
                   
                   
                 C300 
                 0.142 
                 0.126 
               
               
                   
                   
                 C300 
                 0.140 
                 0.126 
               
               
                   
                 413 
                 C400 
                 0.171 
                 0.152 
               
               
                   
                   
                 C400 
                 0.165 
                 0.148 
               
               
                   
                   
                 C400 
                 0.165 
                 0.147 
               
               
                   
                 517 
                 C500 
                 0.186 
                 0.166 
               
               
                   
                   
                 C500 
                 0.187 
                 0.168 
               
               
                   
                   
                 C500 
                 0.186 
                 0.167 
               
               
                   
               
             
          
         
       
     
     Example 15 
     Dissolved 0.1 g glucose in 50 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different concentrations in the range of 320 to 533 mg/L. A 50 mL sample was prepared by mixing apple pomace soaked for 1 day with digested damaged wheat grains and partially digested vegetable market waste. COD of the sample was estimated to be 40300 mg/L (By Merck method and read on photometer). Based on the estimated COD value, diluted samples were prepared in water to achieve a final COD in the range of 310 to 497 mg/L. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 ml of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. The color varied with concentration. In 320 to 533 mg/L glucose solutions, the color varied from C300 to C550. At 320 to 533 mg/L glucose concentrations, average OD 585 varied from 0.159 to 0.212 and OD 635 varied from 0.142 to 0.190. In the COD range of 320.1 to 533.5 mg/L the OD 585 and OD 635 there was an incremental difference of 0.026 and 0.024 for each 106.7 mg/L COD increase, respectively. On the other hand, color of the final sample reaction mixture varied from C300 to C500. 
     At 310 to 497 mg/L COD concentrations of the sample, average OD 585 varied from 0.125 to 0.169 and OD 635 varied from 0.112 to 0.155. In this COD range, there was an incremental difference of 0.022 and 0.021 for each 93 mg/L COD increase at OD 585 and OD 635, respectively. 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 310 to 497 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 15 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction mixture 
               
               
                 and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                 Color of the 
                 OD of the reaction mixture 
                   
               
             
          
           
               
                   
                 COD (mg/L) 
                 reaction mixture 
                 585 nm 
                 635 nm 
               
               
                   
               
             
          
           
               
                 Glucose: 
               
             
          
           
               
                   
                 320 
                 C300 
                 0.160 
                 0.144 
               
               
                   
                   
                 C300 
                 0.157 
                 0.141 
               
               
                   
                   
                 C300 
                 0.159 
                 0.142 
               
               
                   
                 426 
                 C400 
                 0.187 
                 0.170 
               
               
                   
                   
                 C400 
                 0.185 
                 0.167 
               
               
                   
                   
                 C400 
                 0.189 
                 0.172 
               
               
                   
                 535 
                 C550 
                 0.220 
                 0.199 
               
               
                   
                   
                 C550 
                 0.209 
                 0.187 
               
               
                   
                   
                 C550 
                 0.207 
                 0.184 
               
             
          
           
               
                 Sample: Apple pomace + Vegetable waste slurry +  
               
               
                 Damaged wheat grain slurry 
               
             
          
           
               
                   
                 310 
                 C300 
                 0.126 
                 0.114 
               
               
                   
                   
                 C300 
                 0.126 
                 0.112 
               
               
                   
                   
                 C300 
                 0.124 
                 0.111 
               
               
                   
                 404 
                 C400 
                 0.148 
                 0.136 
               
               
                   
                   
                 C400 
                 0.154 
                 0.146 
               
               
                   
                   
                 C400 
                 0.152 
                 0.141 
               
               
                   
                 497 
                 C500 
                 0.171 
                 0.159 
               
               
                   
                   
                 C500 
                 0.168 
                 0.154 
               
               
                   
                   
                 C500 
                 0.167 
                 0.152 
               
               
                   
               
             
          
         
       
     
     Example 16 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of partially digested vegetable waste slurry mixed with potassium hydrogen phosphate salt was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). COD of the sample was estimated to be 777 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 750 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 824 and 852 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.94=COD value (Merck Method) or our COD value (at OD 635)×0.91=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 16 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.162 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.206 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Vegetable waste (filtrate) + Potassium hydrogen phosphate 
               
             
          
           
               
                   
                 Nil 
                  C1500 
                 0.240 
                 ≅1500# 
                 ≅1500 
               
               
                   
                 5 
                 C150 
                 0.101 
                    150# 
                    750 
               
               
                   
                 2 
                 C400 
                 0.150 
                   412 
                    824 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.150 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.167 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.187 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Vegetable waste (filtrate) + Potassium hydrogen phosphate 
               
             
          
           
               
                   
                 Nil 
                  C1500 
                 0.40  
                 ≅1500# 
                 ≅1500 
               
               
                   
                 5 
                 C150 
                 0.101 
                    150# 
                    750 
               
               
                   
                 2 
                 C400 
                 0.150 
                   426 
                    852 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 17 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of partially digested palm oil mill effluent (filtrate) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.159 to 0.205 and 0.149 to 0.183, respectively). 
     COD of the sample was estimated to be 687 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 500 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 874 and 882 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.79=COD value (Merck Method) or our COD value (at OD 635)×0.79=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 17 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Palm oil mill effluent (filtrate) 
               
             
          
           
               
                   
                 Nil 
                 C500 
                 0.236 
                 ≅500# 
                 ≅500 
               
               
                   
                 2 
                 C450 
                 0.159 
                   437  
                   874 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.149 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.166 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.183 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Palm oil mill effluent (filtrate) 
               
             
          
           
               
                   
                 Nil 
                 C500 
                 0.213 
                 ≅500# 
                 ≅500 
               
               
                   
                 2 
                 C450 
                 0.143 
                   441  
                   882 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 18 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of partially digested vegetable waste slurry mixed was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 1930 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 1400 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 1280 and 1288 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.51=COD value (Merck Method) or our COD value (at OD 635)×1.50=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 18 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.161 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.187 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.202 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Vegetable waste slurry 
               
             
          
           
               
                   
                 Nil 
                  C1400 
                 0.294 
                 ≅1400# 
                 ≅1400 
               
               
                   
                 4 
                 C320 
                 0.134 
                   320 
                   1280 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.144 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.167 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.184 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Vegetable waste slurry 
               
             
          
           
               
                   
                 Nil 
                  C1400 
                 0.268 
                 ≅1400# 
                 ≅1400 
               
               
                   
                 4 
                 C320 
                 0.121 
                   322 
                   1288 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 4 to 15 given in Examples 4 to 15. 
               
             
          
         
       
     
     Example 19 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of partially digested Vegetable waste slurry (filtrate) mixed was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 1033 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 1500 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 1632 and 1652 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.63=COD value (Merck Method) or our COD value (at OD 635)×0.62=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 19 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Vegetable waste slurry (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C1500 
                 0.257 
                 ≅1500# 
                 ≅1500 
               
               
                   
                 4 
                 C400 
                 0.148 
                   408 
                   1632 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.145 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.166 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.187 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Vegetable waste slurry (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C1500 
                 0.236 
                 ≅1500# 
                 ≅1500 
               
               
                   
                 4 
                 C400 
                 0.134 
                   413 
                   1652 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 20 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain (filtrate) mixed with vegetable waste slurry (filtrate) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 4067 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 3000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 4170 and 4180 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.97=COD value (Merck Method) or our COD value (at OD 635)×0.97=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 20 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.161 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.206 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) + 
               
               
                 Vegetable waste slurry (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C1400 
                 1.031 
                 ≅1400# 
                 ≅1400 
               
               
                   
                  5 
                 C600 
                 0.234 
                  ≅600# 
                 ≅3000 
               
               
                   
                 10 
                 C400 
                 0.152 
                   417 
                   4170 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.146 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.167 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.186 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) + 
               
               
                 Vegetable waste slurry (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C1400 
                 0.784 
                 ≅1400# 
                 ≅1400 
               
               
                   
                  5 
                 C600 
                 0.213 
                  ≅600# 
                 ≅3000 
               
               
                   
                 10 
                 C400 
                 0.137 
                   418 
                   4180 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 21 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain (filtrate) mixed with vegetable waste slurry was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 ml of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/l corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 4059 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 2900 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 4440 and 4490 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.91=COD value (Merck Method) or our COD value (at OD 635)×0.90=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 21 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C300 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) + Vegetable waste 
               
             
          
           
               
                   
                 Nil 
                  C2000 
                 0.438 
                 ≅2000# 
                 ≅2000 
               
               
                   
                  5 
                 C600 
                 0.229 
                  ≅580# 
                 ≅2900 
               
               
                   
                 10 
                 C450 
                 0.162 
                   444 
                   4440 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.145 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.166 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.187 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) + Vegetable waste 
               
             
          
           
               
                   
                 Nil 
                  C2000 
                 0.378 
                 ≅2000# 
                 ≅2000 
               
               
                   
                  5 
                 C600 
                 0.206 
                  ≅580# 
                 ≅2900 
               
               
                   
                 10 
                 C450 
                 0.146 
                   449 
                   4490 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 22 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain (filtrate) mixed with palm oil mill effluent (filtrate) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 5391 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 3700 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 5344 mg/L. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585 or OD 635)×1.01=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 22 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.161 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.206 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) + Palm oil mill effluent (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C2000 
                 0.533 
                 ≅2000# 
                 ≅2000 
               
               
                   
                  5 
                 C600 
                 0.258 
                  ≅580# 
                 ≅2900 
               
               
                   
                 10 
                 C400 
                 0.183 
                  ≅373# 
                 ≅3730 
               
               
                   
                   16.7 
                 C300 
                 0.133 
                   320 
                   5344 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.146 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.167 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.186 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) + Palm oil mill effluent (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C2000 
                 0.442 
                 ≅2000# 
                 ≅2000 
               
               
                   
                  5 
                 C600 
                 0.234 
                  ≅580# 
                 ≅2900 
               
               
                   
                 10 
                 C400 
                 0.165 
                  ≅373# 
                 ≅3730 
               
               
                   
                   16.7 
                 C300 
                 0.120 
                   320 
                   5344 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 23 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain (filtrate) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 ml of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 6250 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 5800 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 8020 and 6700 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.78=COD value (Merck Method) or our COD value (at OD 635)×0.93=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 23 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C1900 
                 1.325 
                 ≅1900# 
                 ≅1900 
               
               
                   
                 10 
                 C600 
                 0.204 
                  ≅580# 
                 ≅5800 
               
               
                   
                 20 
                 C400 
                 0.146 
                   401 
                   8020 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.149 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.166 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.183 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C1900 
                 1.146 
                 ≅1900# 
                 ≅1900 
               
               
                   
                 10 
                 C600 
                 0.184 
                  ≅580# 
                 ≅5800 
               
               
                   
                 20 
                 C350 
                 0.130 
                   335 
                   6700 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 24 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain (filtrate) slurry was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 9794 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 10,000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 6840 and 6700 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.43=COD value (Merck Method) or our COD value (at OD 635)×1.46=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 24 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 0.834 
                 ≅10000# 
                 ≅10000 
               
               
                   
                 20 
                 C350 
                 0.142 
                    342 
                    6840 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.145 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.166 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.187 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 0.654 
                 ≅10000# 
                 ≅10000 
               
               
                   
                 20 
                 C350 
                 0.127 
                    335 
                    6700 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 25 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain (filtrate) slurry was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 15502 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 10,000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 8000 and 7725 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.94=COD value (Merck Method) or our COD value (at OD 635)×2.01=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 25 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.164 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 0.964 
                 &gt;10000# 
                 &gt;10000  
               
               
                   
                 10 
                 C600 
                 0.267 
                  &gt;600# 
                 &gt;6000 
               
               
                   
                 25 
                 C300 
                 0.137 
                    320 
                   8000 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.152 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.166 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.184 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 0.714 
                 &gt;10000# 
                 &gt;10000  
               
               
                   
                 10 
                 C600 
                 0.252 
                  &gt;600# 
                 &gt;6000 
               
               
                   
                 25 
                 C300 
                 0.122 
                    309 
                   7725 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 26 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Cattle dung slurry was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/l. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). COD of the sample was estimated to be 18515 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 10,000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 8660 mg/L. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585 or OD 635)×2.14=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 26 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.162 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.185 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Cattle dung slurry 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 1.878 
                 ≅10000# 
                 ≅10000 
               
               
                   
                 20 
                 C450 
                 0.157 
                    433 
                    8660 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.148 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.171 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.189 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Cattle dung slurry 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 1.637 
                 ≅10000# 
                 ≅10000 
               
               
                   
                 20 
                 C450 
                 0.145 
                    433 
                    8660 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 27 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Palm Oil Mill Effluent (Digested) with Damaged wheat grains (filtrate) slurry was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/l. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). COD of the sample was estimated to be 19941 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 12,000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 10656 and 11355 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.87=COD value (Merck Method) or our COD value (at OD 635)×1.76=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 27 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.158 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.185 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Palm Oil Mill Effluent (Digested) +  
               
               
                 Damaged wheat grains (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                  6.000* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                 20   
                 C600 
                 0.195 
                  ≅600# 
                 ≅12000 
               
               
                   
                 33.3 
                 C300 
                 0.131 
                    320 
                   10656 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.137 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.163 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.185 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Palm Oil Mill Effluent (Digested) +  
               
               
                 Damaged wheat grains (filtrate) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                  6.000* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                 20   
                 C600 
                 0.182 
                  ≅600# 
                 ≅12000 
               
               
                   
                 33.3 
                 C300 
                 0.122 
                    341 
                   11355 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 28 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Palm Oil Mill Effluent (Digested) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/l. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/l corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 22287 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 20,000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 15840 and 13560 mg/l, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.41=COD value (Merck Method) or our COD value (at OD 635)×1.64=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of standard reaction mixture can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 28 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.162 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.185 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Palm Oil Mill Effluent (Digested) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                  6.000* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                 10 
                  C2000 
                 0.345 
                  &gt;2000# 
                 &gt;20000 
               
               
                   
                 50 
                 C250 
                 0.119 
                  ≅250 
                 ≅12500 
               
               
                   
                 40 
                 C400 
                 0.143 
                    396 
                   15840 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.148 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.171 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.189 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Palm Oil Mill Effluent (Digested) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                  6.000* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                 10 
                  C2000 
                 0.330 
                  &gt;2000# 
                 &gt;20000 
               
               
                   
                 50 
                 C250 
                 0.109 
                  ≅250 
                 ≅12500 
               
               
                   
                 40 
                 C400 
                 0.131 
                    339 
                   13560 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 29 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Palm Oil Mill Effluent (Digested) with Apple pomace was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 44620 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 40,000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 38640 and 40080 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.15=COD value (Merck Method) or our COD value (at OD 635)×1.11=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 29 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.155 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.185 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Palm Oil Mill Effluent (Digested) + Apple pomace 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                  6.000* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                  20 
                  C2000 
                 0.352 
                  &gt;2000# 
                 &gt;40000 
               
               
                   
                 100 
                  C2000 
                 0.220 
                  ≅250# 
                 ≅25000 
               
               
                   
                 120 
                 C300 
                 0.132 
                     320 
                   38640 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.137 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.163 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.185 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Palm Oil Mill Effluent (Digested) + Apple pomace 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                  6.000* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                  20 
                  C2000 
                 0.322 
                  &gt;2000# 
                 &gt;40000 
               
               
                   
                 100 
                  C2000 
                 0.190 
                  ≅250# 
                 ≅25000 
               
               
                   
                 120 
                 C300 
                 0.119 
                    334 
                   40080 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 30 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Vegetable waste slurry with Apple pomace was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/l. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 35484 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 40,000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 40000 and 34000 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.89=COD value (Merck Method) or our COD value (at OD 635)×1.04=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 30 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.163 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.185 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.202 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Vegetable waste slurry + Apple pomace 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 6.00* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                  20 
                  C2000 
                 0.349 
                  &gt;2000# 
                 ≅40000 
               
               
                   
                 100 
                 C400 
                 0.145 
                    400 
                   40000 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.147 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.170 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.187 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Vegetable waste slurry + Apple pomace 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 6.00* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                  20 
                  C2000 
                 0.318 
                  &gt;2000# 
                 ≅40000 
               
               
                   
                 100 
                 C400 
                 0.130 
                    340 
                   34000 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 31 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain (filtrate) with Apple pomace was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 36018 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 30,000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 42600 mg/l. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585 or OD 635)×0.84=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 31 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.164 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) + Apple pomace 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                  6.000* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                 10 
                  C1500 
                 0.442 
                  &gt;1500# 
                 &gt;15000 
               
               
                   
                 50 
                 C600 
                 0.236 
                  &gt;600# 
                 &gt;30000 
               
               
                   
                 100  
                 C400 
                 0.155 
                    426 
                   42600 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.152 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.166 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.184 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (filtrate) + Apple pomace 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                  6.000* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                 10 
                  C1500 
                 0.377 
                  &gt;1500# 
                 &gt;15000 
               
               
                   
                 50 
                 C600 
                 0.212 
                  &gt;600# 
                 &gt;30000 
               
               
                   
                 100  
                 C400 
                 0.138 
                    426 
                   42600 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 32 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain slurry with Tea with Sodium sulphate was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 53867 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 100,000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 49896 and 51744 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.08=COD value (Merck Method) or our COD value (at OD 635)×1.04=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 32 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.163 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.183 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain + Tea + Sodium sulphate 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 6.00* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                  10 
                  C10000 
                  0.801* 
                 ≅10000# 
                 ≅10000 
               
               
                   
                 154 
                 C300 
                 0.138 
                    324 
                   49896 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.150 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.167 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.187 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain + Tea + Sodium sulphate 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 6.00* 
                 &gt;10000# 
                  &gt;10000 
               
               
                   
                  10 
                  C10000 
                  0.801* 
                 ≅10000# 
                 ≅100000 
               
               
                   
                 154 
                 C300 
                 0.124 
                    336 
                    51744 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 33 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Apple pomace was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). COD of the sample was estimated to be 55890 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 50,000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 65875 and 66500 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.85=COD value (Merck Method) or our COD value (at OD 635)×0.84=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 33 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.161 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.206 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Apple pomace 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 6.00* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                  10 
                  C5000 
                 0.525 
                  ≅5000# 
                 ≅50000 
               
               
                   
                 125 
                 C500 
                 0.171 
                    527 
                   65875 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.150 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.167 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.188 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Apple pomace 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 6.00* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                  10 
                  C5000 
                 0.428 
                  ≅5000# 
                 ≅50000 
               
               
                   
                 125 
                 C500 
                 0.157 
                    532 
                   66500 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 34 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain with Tea was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/l. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 58760 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 64800 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 78848 and 84546 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.74=COD value (Merck Method) or our COD value (at OD 635)×0.70=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 34 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.162 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.206 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain + Tea 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 6.00* 
                 &gt;10000# 
                  &gt;10000 
               
               
                   
                  10 
                  C10000 
                 6.00* 
                 &gt;10000# 
                 ≅100000 
               
               
                   
                 100 
                  C1500 
                 0.272 
                  ≅1500# 
                 ≅150000 
               
               
                   
                 270 
                 C250 
                 0.124 
                  ≅240# 
                  ≅64800 
               
               
                   
                 154 
                 C500 
                 0.164 
                    512 
                    78848 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.150 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.167 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C500 
                 0.187 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain + Tea 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 6.00* 
                 &gt;10000# 
                 &gt;10000 
               
               
                   
                  10 
                  C10000 
                 6.00* 
                 &gt;10000# 
                 ≅100000  
               
               
                   
                 100 
                  C1500 
                 0.272 
                  ≅1500# 
                 ≅150000  
               
               
                   
                 270 
                 C250 
                 0.124 
                  ≅240# 
                   64800 
               
               
                   
                 154 
                 C500 
                 0.160 
                    549 
                   84546 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 35 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Trizyme with Tea was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). COD of the sample was estimated to be 61088 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 100,000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 79156 and 67914 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.77=COD value. (Merck Method) or our COD value (at OD 0.635)×0.90=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 35 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the  
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.163 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.183 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Trizyme + Tea 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 6.00* 
                 &gt;10000# 
                  &gt;10000 
               
               
                   
                  50 
                  C2000 
                 0.338 
                  ≅2000# 
                 ≅100000 
               
               
                   
                 154 
                 C500 
                 0.164 
                    514 
                    79156 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.152 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.170 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.184 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Trizyme + Tea 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 6.00* 
                 &gt;10000# 
                  &gt;10000 
               
               
                   
                  50 
                  C2000 
                 0.305 
                  ≅2000# 
                 ≅100000 
               
               
                   
                 154 
                 C500 
                 0.147 
                    441 
                    67914 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 36 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Tea was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). COD of the sample was estimated to be 1,36,608 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 200,000 to 220,000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 173983 and 172649 mg/L, respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.78=COD value (Merck Method) or our COD value (at OD 635)×0.79=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value, color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 36 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.161 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.187 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.202 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 6.00* 
                 &gt;10000# 
                  &gt;10000 
               
               
                   
                  20 
                  C10000 
                 1.648 
                 &gt;10000# 
                 ≅200000 
               
               
                   
                 200 
                  C1100 
                 0.216 
                  ≅1100# 
                 ≅220000 
               
               
                   
                   333.3 
                 C500 
                 0.164 
                    522 
                   173983 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.144 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.167 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.184 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 6.00* 
                 &gt;10000# 
                  &gt;10000 
               
               
                   
                  20 
                  C10000 
                 1.531 
                 &gt;10000# 
                 ≅200000 
               
               
                   
                 200 
                  C1100 
                 0.196 
                  ≅1100# 
                 ≅220000 
               
               
                   
                   333.3 
                 C500 
                 0.148 
                    518 
                   172649 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 37 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain (as such) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 6210 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 4000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 4270 mg/l and 3370 mg/l. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.45=COD value (Merck Method). or our COD value (at OD 635)×1.84=COD (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 37 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the  
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.165 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.193 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.213 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (as such) 
               
             
          
           
               
                   
                 Nil 
                  C1100 
                 0.491 
                 ≅1100 
                 ≅1100# 
               
               
                   
                 10 
                 C400 
                 0.154 
                    427 
                   4270  
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.148 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.172 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.191 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (as such) 
               
             
          
           
               
                   
                 Nil 
                  C1100 
                 0.401 
                 ≅1100 
                 ≅1100# 
               
               
                   
                 10 
                 C400 
                 0.130 
                    337 
                   3370  
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 38 
     Dissolved 0.3 g glucose in 50 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 4710.4 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 4800 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 5220 and 4998 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.90=COD value (Merck Method) or our COD value (at OD 635)×0.94=COD (Merck Method). Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 38 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the  
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.163 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.176 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.226 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C1500 
                 0.652 
                 1500 
                 ≅1500  
               
               
                   
                 10 
                 C200 
                 0.187 
                  224 
                 ≅2240# 
               
               
                   
                 12 
                 C400 
                 0.147 
                  435 
                   5220  
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.146 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.159 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Damaged wheat grain (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C1500 
                 0.551 
                 1500 
                 ≅1500  
               
               
                   
                 10 
                 C200 
                 0.168 
                  224 
                 ≅2240# 
               
               
                   
                 12 
                 C400 
                 0.127 
                  416 
                   4998  
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 39 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Palm oil mill effluent (as such) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 15,801 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 12000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 13389 and 13506 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value at (OD 585)×1.18=COD value (Merck Method) or our COD value (at OD 635)×1.17=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 39 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the  
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.165 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.193 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.213 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Palm oil Mill effluent (as such) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                  C1900 
                 0.394 
                   ≅1900 
                  ≅19,000# 
               
               
                   
                 30 
                 C400 
                 0.165 
                     446.3 
                    13389 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.148 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.172 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.191 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Palm oil Mill effluent (as such) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10000 
                 &gt;10000  
               
               
                   
                 10 
                  C1900 
                 0.360 
                  ≅1900 
                 ≅19000# 
               
               
                   
                 30 
                 C400 
                 0.148 
                     450.2  
                   13506  
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 40 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Palm oil mill effluent (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). COD of the sample was estimated to be 1129.6 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 800 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 970 and 950 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.16=COD value (Merck Method) or our COD value (at OD 635)×1.19=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 40 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the  
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.163 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.176 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.226 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Palm oil Mill effluent (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C1500 
                 0.263 
                 ≅1500 
                 ≅1500# 
               
               
                   
                 2 
                 C400 
                 0.171 
                    485 
                   970 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.146 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.159 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Palm oil Mill effluent (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C1500 
                 0.242 
                 ≅1500 
                 ≅1500# 
               
               
                   
                 2 
                 C400 
                 0.152 
                    475 
                   950 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 41 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain and POME (as such) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 9706 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 9000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 7660 and 7567 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.27=COD value (Merck Method) or our COD value (at OD 635)×1.12. 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 41 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the  
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.165 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.193 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.213 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: DWS (S3) + POME (as such) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 1.231 
                 &gt;10,000 
                 &gt;10,000  
               
               
                   
                 10 
                  C1500 
                 0.256 
                   ≅1500 
                 ≅15,000  
               
               
                   
                 20 
                 C450 
                 0.186 
                   ≅450 
                  ≅9000# 
               
               
                   
                 25 
                 C300 
                 0.132 
                     306.4 
                    7660 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.148 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.172 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.191 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: DWS (S3) + POME (as such) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 0.994 
                 10,000   
                 &gt;10,000 
               
               
                   
                 10 
                  C1500 
                 0.221 
                 ≅1500    
                 ≅45,000 
               
               
                   
                 20 
                 C450 
                 0.165 
                 ≅450   
                   ≅9000# 
               
               
                   
                 25 
                 C300 
                 0.117 
                   302.6 
                     7567 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 42 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain and POME (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 4427.5 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 4000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 4068 and 3936 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.09=COD value (Merck Method) or our COD value (at OD 635)×1.12. 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 42 
               
             
             
               
                   
               
               
                 DWS (S3) + POME (ssp) 
               
               
                 Correlation between COD concentration, color of the  
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.165 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.193 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.213 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: DWS (S3) + POME (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C1500 
                 0.520 
                 &gt;1500 
                 &gt;1500 
               
               
                   
                 10 
                 C400 
                 0.185 
                    400 
                  ≅4000# 
               
               
                   
                 12 
                 C300 
                 0.146 
                    339 
                   4068 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.148 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.172 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.191 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: DWS (S3) + POME (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C1500 
                 0.427 
                 &gt;1500 
                 &gt;1500  
               
               
                   
                 10 
                 C400 
                 0.165 
                  ≅400 
                 ≅4000# 
               
               
                   
                 12 
                 C300 
                 0.127 
                    328 
                   3936  
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 43 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Tea (as such) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). COD of the sample was estimated to be 74,589 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 90000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 101750 and 102000 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value at (OD 585 or OD 635)×0.73=COD value (Merck Method). 
     Hence, for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 43 
               
             
             
               
                   
               
               
                 Tea (as such) 
               
               
                 Correlation between COD concentration, color of the  
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.223 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: TEA (as such) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000      
               
               
                   
                  10 
                  C10000 
                 — 
                 &gt;10,000 
                 &gt;1,00,000       
               
               
                   
                 100 
                  C1900 
                 0.267 
                   ≅1900 
                 ≅1,90,000      
               
               
                   
                   111.1 
                  C1300 
                 0.245 
                   ≅1300 
                 ≅1,44,430      
               
               
                   
                   166.7 
                 C500 
                 0.206 
                   ≅550 
                     ≅91,685      
               
               
                   
                 200 
                 C400 
                 0.175 
                   ≅450 
                     ≅90,000#     
               
               
                   
                 250 
                 C300 
                 0.145 
                     407 
                  101750     
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.141 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.164 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.198 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: TEA (as such) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000      
               
               
                   
                  10 
                  C10000 
                 — 
                 &gt;10,000 
                 &gt;1,00,000       
               
               
                   
                 100 
                  C1900 
                 0.237 
                   ≅1900 
                 ≅1,90,000      
               
               
                   
                   111.1 
                  C1300 
                 0.214 
                   ≅1300 
                 ≅1,44,430      
               
               
                   
                   166.7 
                 C500 
                 0.182 
                   ≅550 
                     ≅91,685      
               
               
                   
                 200 
                 C400 
                 0.155 
                   ≅450 
                     ≅90,000#     
               
               
                   
                 250 
                 C300 
                 0.128 
                     408 
                  102000     
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Table 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 44 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Tea (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). COD of the sample was estimated to be 67,528 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 75015 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 81380 and 18380 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585 or OD 635)×0.83=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 44 
               
             
             
               
                   
               
               
                 Tea (ssp) 
               
               
                 Correlation between COD concentration, color of the  
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.223 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: TEA (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000  
                 ≅&gt;10,000 
               
               
                   
                  10 
                  C10000 
                 — 
                 &gt;10,000  
                 &gt;1,00,000 
               
               
                   
                 100 
                  C1800 
                 0.244 
                  ≅1800 
                 ≅1,80,000 
               
               
                   
                 125 
                 C550 
                 0.222 
                  ≅550 
                   ≅68,750 
               
               
                   
                   166.7 
                 C450 
                 0.173 
                  ≅450 
                   ≅75,015# 
               
               
                   
                 200 
                 C300 
                 0.145 
                    407 
                      81380 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.141 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.164 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.198 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: TEA (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000  
                 ≅&gt;10,000 
               
               
                   
                  10 
                  C10000 
                 — 
                 &gt;10,000  
                 &gt;1,00,000 
               
               
                   
                 100 
                  C1800 
                 0.216 
                  ≅1800 
                 ≅1,80,000 
               
               
                   
                 125 
                 C550 
                 0.190 
                  ≅550 
                   ≅68,750 
               
               
                   
                   166.7 
                 C450 
                 0.152 
                  ≅450 
                   ≅75,015# 
               
               
                   
                 200 
                 C300 
                 0.128 
                    408 
                      81700 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 45 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Apple pomace (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). COD of the sample was estimated to be 39,284 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 30760 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 43000 and 43500 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.91=COD value (Merck Method) or our COD value (at OD 635)×435=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 45 
               
             
             
               
                   
               
               
                 Apple Pomace (ssp) 
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.187 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.210 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: APPLE POMACE (ssp) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C1600  
                 0.392 
                   ≅1600 
                 ≅16,000 
               
               
                   
                 16.7 
                 C800  
                 0.354 
                   ≅800 
                 ≅13,360 
               
               
                   
                 50 
                 C550  
                 0.244 
                   ≅550 
                 ≅27,500 
               
               
                   
                 76.9 
                 C400  
                 0.178 
                   ≅400 
                  ≅30,760# 
               
               
                   
                 100 
                 C300  
                 0.154 
                     430 
                    43000 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.141 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.167 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.191 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: APPLE POMACE (ssp) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C1600  
                 0.336 
                   ≅1600 
                 ≅16,000 
               
               
                   
                 16.7 
                 C800  
                 0.317 
                   ≅800 
                 ≅13,360 
               
               
                   
                 50 
                 C550  
                 0.217 
                   ≅550 
                 ≅27,500 
               
               
                   
                 76.9 
                 C400  
                 0.159 
                   ≅400 
                  ≅30,760# 
               
               
                   
                 100 
                 C300  
                 0.139 
                     435 
                    45000 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 46 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Tea and Apple pomace (as such) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 56,948 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 40000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 68441 and 681334 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.83=COD value (Merck Method) or our COD value (at OD 635)×0.84=COD value (Merck Method).) 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 46 
               
             
             
               
                   
               
               
                 Tea + Apple Pomace (as such) 
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.157 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.176 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.202 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: TEA + APPLE POMACE (as such) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C1500  
                 0.603 
                   ≅1500 
                 ≅15,000 
               
               
                   
                 50 
                 C700  
                 0.295 
                   ≅700 
                 ≅35,000 
               
               
                   
                 100 
                 C400  
                 0.187 
                   ≅400 
                  ≅40,000# 
               
               
                   
                 153.8 
                 C450  
                 0.150 
                     445 
                    68441 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.142 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.155 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.182 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: TEA + APPLE POMACE (as such) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C1500  
                 0.465 
                   ≅1500 
                 ≅15,000 
               
               
                   
                 50 
                 C700  
                 0.262 
                   ≅700 
                 ≅35,000 
               
               
                   
                 100 
                 C400  
                 0.168 
                   ≅400 
                  ≅40,000# 
               
               
                   
                 153.8 
                 C400  
                 0.122 
                     443 
                    68134 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 47 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Tea+Apple pomace (ssp) and POME was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 60,398 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 45000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 66,134 and 67,364 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.91=COD value (Merck Method) or our COD value (at OD 635)×0.90=COD value (Merck Method).) 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 47 
               
             
             
               
                   
               
               
                 Tea + Apple Pomace (ssp) 
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.157 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.176 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.202 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: TEA + APPLE POMACE (ssp) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C1400  
                 0.621 
                   ≅1400 
                 ≅14,000 
               
               
                   
                 50 
                 C800  
                 0.284 
                   ≅800 
                 ≅40,000 
               
               
                   
                 100 
                 C450  
                 0.181 
                   ≅450 
                 ≅45,000 
               
               
                   
                 153.8 
                 C400  
                 0.145 
                     430 
                   66,134 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.142 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.155 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.182 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: TEA + APPLE POMACE (ssp) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C1400  
                 0.473 
                   ≅1400 
                 ≅14,000 
               
               
                   
                 50 
                 C800  
                 0.284 
                   ≅800 
                 ≅40,000 
               
               
                   
                 100 
                 C450  
                 0.159 
                   ≅450 
                 ≅45,000 
               
               
                   
                 153.8 
                 C400  
                 0.130 
                     438 
                   67,364 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 48 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Digested POME (as such) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). COD of the sample was estimated to be 5993.8 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 1700 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 3120 and 3160 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.92=COD value (Merck Method) or our COD value (at OD 635)×1.90=COD value (Merck Method).) 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 48 
               
             
             
               
                   
               
               
                 Digested POME (as such) 
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.162 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.189 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.207 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested POME (as such) 
               
             
          
           
               
                   
                 Nil 
                 C1700 
                 1.021 
                 ≅1700 
                 ≅1700# 
               
               
                   
                 10 
                 C250  
                 0.132 
                    312 
                   3120  
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.146 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.171 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C300  
                 0.187 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested POME (as such) 
               
             
          
           
               
                   
                 Nil 
                 C1700 
                 0.889 
                 ≅1700 
                 ≅1700# 
               
               
                   
                 10 
                 C250  
                 0.120 
                    316 
                   3160  
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 49 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Digested POME (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). COD of the sample was estimated to be 588.4 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 400 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 535 and 458 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.10=COD value (Merck Method) or our COD value (at OD 635)×1.30=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 49 
               
             
             
               
                   
               
               
                 Digested POME (ssp) 
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.162 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.189 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.207 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested POME (ssp) 
               
             
          
           
               
                   
                 Nil 
                 C400 
                 0.168 
                 535 
                 535 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.146 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.171 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.187 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested POME (ssp) 
               
             
          
           
               
                   
                 Nil 
                 C400 
                 0.148 
                 458 
                 458 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 50 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Digested POME and Tea (as such) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 59,593 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 50000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 41600 and 41900 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.43=COD value (Merck Method) or our COD value (at OD 635)×1.42=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used. as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 50 
               
             
             
               
                   
               
               
                 Digested Pome + Tea (as such) 
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.162 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.187 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.208 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested Pome + Tea (as such) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C5000  
                 0.416 
                   ≅5000 
                  ≅50,000# 
               
               
                   
                 100 
                 C400  
                 0.149 
                     416 
                    41600 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.141 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.162 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C500  
                 0.192 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested Pome + Tea (as such) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C5000  
                 0.353 
                   ≅5000 
                  ≅50,000# 
               
               
                   
                 100 
                 C400  
                 0.130 
                     419 
                    41900 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 51 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Digested POME and Tea (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 39,928 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 20000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 38556 and 36985 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.43=COD value (Merck Method) or our COD value (at OD 635)×1.42=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 51 
               
             
             
               
                   
               
               
                 Digested Pome + Tea (ssp) 
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.162 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.187 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.208 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested Pome + Tea (ssp) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 ≅10,000 
               
               
                   
                 10 
                 C2000  
                 0.386 
                   ≅2000 
                  ≅20,000# 
               
               
                   
                 100 
                 C200  
                 0.107 
                    200 
                  20,000 
               
               
                   
                 71.4 
                 C500  
                 0.175 
                    540 
                   38556 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.141 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.162 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.192 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested Pome + Tea (ssp) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 ≅10,000 
               
               
                   
                 10 
                 C2000  
                 0.336 
                   ≅2000 
                  ≅20,000# 
               
               
                   
                 100 
                 C200  
                 0.092 
                    200 
                  20,000 
               
               
                   
                 71.4 
                 C500  
                 0.155 
                    518 
                   36985 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 52 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Digested POME and Apple pomace (as such) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 24,932 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 15000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 15800 and 16955 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.58=COD value (Merck Method) or our COD value (at OD 635)×1.47=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 52 
               
             
             
               
                   
               
               
                 Digested Pome + Apple Pomace (as such) 
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.158 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested Pome + Apple Pomace (as such) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C1500  
                 0.336 
                   ≅1500 
                  ≅15,000# 
               
               
                   
                 50 
                 C400  
                 0.130 
                    316 
                   15800 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.137 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.159 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.191 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested Pome + Apple Pomace (as such) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C1500  
                 0.305 
                   ≅1500 
                  ≅15,000# 
               
               
                   
                 50 
                 C400  
                 0.121 
                    339 
                   16955 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 53 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Digested Palm oil mill effluent (POME) and Apple pomace (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 21,666 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 16000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 32600 and 41310 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.66=COD value (Merck Method) or our COD value (at OD 635)×0.52=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or QD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 53 
               
             
             
               
                   
               
               
                 Digested Pome + Apple Pomace (ssp) 
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.158 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested Pome + Apple Pomace (ssp) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C1600  
                 0.357 
                   ≅1600 
                  ≅16,000# 
               
               
                   
                 100 
                 C300  
                 0.134 
                    326 
                   32600 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.137 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.159 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.191 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested Pome + Apple Pomace (ssp) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C1600  
                 0.357 
                   ≅1600 
                  ≅16,000# 
               
               
                   
                 100 
                 C300  
                 0.134 
                    413 
                   41300 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 54 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Digested POME, Apple pomace and Tea (as such) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 34,569 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 45000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 35774 and 36552 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.97=COD value (Merck Method) or our COD value (at OD 635)×0.94=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 54 
               
             
             
               
                   
               
               
                 Digested Pome + Apple Pomace + Tea (as such) 
               
               
                 Correlation between COD concentration, color of the 
               
               
                 reaction mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.160 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.185 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.211 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested Pome + Apple Pomace + Tea (as such) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C4500  
                 0.428 
                   ≅4500 
                  ≅45,000# 
               
               
                   
                 100 
                 C450  
                 0.189 
                   ≅450 
                  ≅45,000# 
               
               
                   
                 111.1 
                 C300  
                 0.134 
                    322 
                   35774 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300  
                 0.141 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400  
                 0.162 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550  
                 0.197 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested Pome + Apple Pomace + Tea (as such) 
               
             
          
           
               
                   
                 Nil 
                 C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000 
               
               
                   
                 10 
                 C4500  
                 0.375 
                   ≅4500 
                  ≅45,000# 
               
               
                   
                 100 
                 C450  
                 0.173 
                   ≅450 
                  ≅45,000# 
               
               
                   
                 111.1 
                 C300  
                 0.121 
                    329 
                   36552 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 55 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Digested POME, Apple pomace and Tea (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 34,040 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 40000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 46800 and 48100 mg/l. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.73=COD value (Merck Method) or our COD value (at OD 635)×0.71=COD value (Merck Method). Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 55 
               
             
             
               
                   
               
               
                 Digested Pome + Apple Pomace + Tea (ssp) 
               
               
                 Correlation between COD concentration, color of the reaction  
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.160 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.185 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.211 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested Pome + Apple Pomace + Tea (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000   
               
               
                   
                 10 
                  C4000 
                 0.373 
                   ≅4000 
                  ≅40,000#   
               
               
                   
                 100 
                 C400 
                 0.166 
                     468 
                  46800 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.141 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.162 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.197 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested Pome + Apple Pomace + Tea (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000 
                 &gt;10,000   
               
               
                   
                 10 
                  C4000 
                 0.322 
                   ≅4000 
                  ≅40,000#   
               
               
                   
                 100 
                 C400 
                 0.149 
                     481 
                  48100 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 56 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Tea and Apple pomace (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 75,716 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 78540 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 86400 and 83600 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×0.88=COD value (Merck Method) or our COD value (at OD 635)×0.91=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 56 
               
             
             
               
                   
               
               
                 Tea + Apple Pomace (ssp) 
               
               
                 Correlation between COD concentration, color of the reaction  
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000  
                  ≅&gt;10,000  
               
               
                   
                 10 
                  C5500 
                 0.372 
                  ≅5500 
                   ≅55,000 
               
               
                   
                 100 
                  C1600 
                 0.225 
                  ≅1600 
                 ≅1,60,000 
               
               
                   
                 142.8 
                 C550 
                 0.175 
                  ≅550 
                   ≅78,540# 
               
               
                   
                 200 
                 C400 
                 0.157 
                    432 
                      86400 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.143 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.168 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.186 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000  
                  ≅&gt;10,000  
               
               
                   
                 10 
                  C5500 
                 0.295 
                  ≅5500 
                   ≅55,000 
               
               
                   
                 100 
                  C1600 
                 0.201 
                  ≅1600 
                 ≅1,60,000 
               
               
                   
                 142.8 
                 C550 
                 0.155 
                  ≅550 
                   ≅78,540# 
               
               
                   
                 200 
                 C400 
                 0.136 
                    418 
                      83600 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 57 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 11,707 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 1400 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 5160 and 5040 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×2.26=COD value (Merck Method) or our COD value (at OD 635)×2.31=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 57 
               
             
             
               
                   
               
               
                 DWS (S3) (ssp) 
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.186 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.205 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: DWS (S3) (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C1400 
                 0.636 
                 ≅1400 
                  ≅1400# 
               
               
                   
                 10 
                 C400 
                 0.165 
                    516 
                   5160 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.143 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.168 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.186 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: DWS (S3) (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C1400 
                 0.494 
                 ≅1400 
                  ≅1400# 
               
               
                   
                 10 
                 C400 
                 0.147 
                    504 
                   5040 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 58 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Tea, Apple pomace and Damaged wheat grain (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 22,689.5 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 20000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 22450 and 16950 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×2.26=COD value (Merck Method) or our COD value (at OD 635)×2.31=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 58 
               
             
             
               
                   
               
               
                 Tea + Apple Pomace + DWS (S3) (ssp) 
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.161 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.185 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.209 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace + DWS (S3) (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000  
                 &gt;10,000   
               
               
                   
                 10 
                  C4000 
                 0.356 
                  ≅4000 
                 ≅40,000   
               
               
                   
                 66.7 
                 C300 
                 0.127 
                  ≅300 
                  ≅20,000#   
               
               
                   
                 50 
                 C400 
                 0.162 
                    449 
                  22450 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.142 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.163 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.198 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace + DWS (S3) (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000  
                 &gt;10,000   
               
               
                   
                 10 
                  C4000 
                 0.319 
                  ≅4000 
                 ≅40,000   
               
               
                   
                 66.7 
                 C300 
                 0.113 
                  ≅300 
                  ≅20,000#   
               
               
                   
                 50 
                 C400 
                 0.142 
                    339 
                  16950 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 59 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Tea, Apple pomace, Damaged wheat grain and Peptone (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 36,176 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 20000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 20900 and 21050 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.73=COD value (Merck Method) or our COD value (at OD 635)×1.72=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 59 
               
             
             
               
                   
               
               
                 Tea + Apple Pomace + DWS (S3) + Peptone (ssp) 
               
               
                 Correlation between COD concentration, color of the reaction  
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.161 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.185 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.209 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace + DWS (S3) + Peptone (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000  
                 &gt;10,000   
               
               
                   
                 10 
                  C2000 
                 0.348 
                  ≅2000 
                  ≅20,000#   
               
               
                   
                 50 
                 C300 
                 0.151 
                    418 
                  20900 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.142 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.163 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.198 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace + DWS (S3) + Peptone (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000  
                 &gt;10,000   
               
               
                   
                 10 
                  C20000 
                 0.315 
                  ≅2000 
                  ≅20,000#   
               
               
                   
                 50 
                 C300 
                 0.134 
                    421 
                  21050 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 60 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Tea, Apple Pomace and Dabu (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 77,786 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 55000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 71714 and 74348 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.08=COD value (Merck Method) or our COD value (at OD 635)×1.05=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 60 
               
             
             
               
                   
               
               
                 Tea + Apple Pomace + Dabu (ssp) 
               
               
                 Correlation between COD concentration, color of the reaction  
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.187 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.206 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace + Dabu (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000  
                 &gt;10,000   
               
               
                   
                 10 
                  C5000 
                 — 
                  ≅5000 
                 ≅50,000   
               
               
                   
                 100 
                 C550 
                 0.216 
                  ≅550 
                  ≅55,000#   
               
               
                   
                 166.7 
                 C400 
                 0.157 
                    430 
                  71681 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.141 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.162 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.195 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace + Dabu (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000  
                 &gt;10,000   
               
               
                   
                 10 
                  C5000 
                 — 
                  ≅5000 
                 ≅50,000   
               
               
                   
                 100 
                 C550 
                 0.195 
                  ≅550 
                  ≅55,000#   
               
               
                   
                 166.7 
                 C400 
                 0.141 
                    446 
                  74348 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 61 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain and Dabu (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 65,251 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 45000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 63625 and 58000 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.02=COD value (Merck Method) or our COD value (at OD 635)×1.12=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 61 
               
             
             
               
                   
               
               
                 DWS (S3) + Dabu (ssp) 
               
               
                 Correlation between COD concentration, color of the reaction  
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.187 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.206 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: DWS (S3) + Dabu (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C5500 
                 — 
                 5500 
                  ≅5500 
               
               
                   
                 10 
                  C4000 
                 — 
                 4000 
                 ≅40,000   
               
               
                   
                 100 
                 C450 
                 0.168 
                 450 
                 ≅45,000# 
               
               
                   
                 125 
                 C300 
                 0.163 
                 509 
                  63625 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.141 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.162 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.195 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: DWS (S3) + Dabu (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C5500 
                 — 
                 5500 
                   ≅5500 
               
               
                   
                 10 
                  C4000 
                 — 
                 4000 
                 ≅40,000 
               
               
                   
                 100 
                 C450 
                 0.150 
                 450 
                  ≅45,000# 
               
               
                   
                 125 
                 C300 
                 0.145 
                 464 
                    58000 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 62 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Tea, Apple Pomace, Damaged wheat grain and NaCl (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 27,163 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 10000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 16300 and 17450 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.67=COD value (Merck Method) or our COD value (at OD 635)×1.56=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 62 
               
             
             
               
                   
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.158 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.185 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.207 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace + DWS (S3) + NaCl (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 ≅10,000 
                  ≅10,000#   
               
               
                   
                 50 
                 C300 
                 0.134 
                     326 
                  16300 
               
               
                   
                 66.7 
                 C300 
                 0.112 
                     300 
                 20,010 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.132 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.160 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.195 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace + DWS (S3) + NaCl (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 ≅10,000 
                  ≅10,000#   
               
               
                   
                 50 
                 C300 
                 0.120 
                     349 
                  17450 
               
               
                   
                 66.7 
                 C300 
                 0.099 
                     300 
                 20,010 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 63 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Tea, Apple Pomace, Damaged wheat grain and Glucose (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 53,866 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 50000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 517000 and 41600 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.04=COD value (Merck Method) or our COD value (at OD 635)×1.30=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 63 
               
             
             
               
                   
               
               
                 Tea + Apple Pomace + DWS (S3) + Glucose (ssp) 
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                 COD 
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 (mg/L) 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                   
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.158 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.185 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.207 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace + DWS (S3) + Glucose (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000  
                 &gt;10000   
               
               
                   
                 10 
                  C5000 
                 — 
                    5000 
                  50,000#  
               
               
                   
                 100 
                 C500 
                 0.167 
                    517 
                 51700 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.132 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.160 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.195 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace + DWS (S3) + Glucose (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                 — 
                 &gt;10,000  
                 &gt;10000   
               
               
                   
                 10 
                  C5000 
                 — 
                    5000 
                  50,000#  
               
               
                   
                 100 
                 C400 
                 0.150 
                    416 
                 41600 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 64 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Damaged wheat grain (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 6649.3 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 500 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 5260 and 5190 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.26=COD value (Merck Method) or our COD value (at OD 635)×1.30=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 64 
               
             
             
               
                   
               
               
                 DWS (S3) (ssp) 
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.187 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.210 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: DWS (S3) (ssp) 
               
             
          
           
               
                   
                 Nil 
                 C550 
                 — 
                 550 
                  550# 
               
               
                   
                 10 
                 C400 
                 0.172 
                 526 
                 5260 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.142 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.167 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.189 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Digested POME (ssp) 
               
             
          
           
               
                   
                 Nil 
                 C550 
                 — 
                 550 
                  550# 
               
               
                   
                 10 
                 C400 
                 0.151 
                 531 
                 5310 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     Example 65 
     Dissolved 0.15 g glucose in 25 mL distilled water. Aliquots from the stock solution were taken and diluted with water to achieve different COD concentrations in the range of 320 to 535 mg/L. A 30 mL sample of Tea, Apple Pomace, Damaged wheat grain and Glucose (ssp) was taken. Weighed 0.02 g HgSO 4  in separate 15 mL test tubes. 1.0 mL of glucose solution and sample were added to each test tube separately and mixed well. 0.5 mL of K 2 Cr 2 O 7  was added to each sample. 1.5 mL H 2 SO 4  silver sulphate reagent was added slowly with continuous shaking. The color of the reaction mixture was noted down visually within 15 sec of incubation and also recorded spectrophotometrically at 585 and 635 nm against air. An approximate COD value of the sample was estimated from the color of standard reaction mixture prepared with glucose as reference material in the COD range of 200 to 100000 mg/L. OD 585 and OD 635 of the reaction mixture was read spectrophotometrically. OD 585 and 635 nm in the range of 0.130 to 0.175 and 0.120 to 0.160 respectively were considered and calculated with reference to glucose standard. (Glucose COD in the range of 320 to 535 mg/L corresponds to OD 585 and 635 nm in the range of 0.157 to 0.207 and 0.142 to 0.189, respectively). 
     COD of the sample was estimated to be 30,866 mg/L. (By Merck method and read on photometer). 
     Based on the color of the reaction mixture, COD of the sample was estimated to be around 20000 mg/L. On the basis of the dilution method and the spectrophotometric reading at OD 585 and OD 635 of the sample, COD was estimated to be 20,850 and 20,450 mg/l respectively. A comparison with the COD value calculated through Merck method reveals the following relation i.e. Our COD value (at OD 585)×1.48=COD value (Merck Method) or our COD value (at OD 635)×1.51=COD value (Merck Method). 
     Hence for a preliminary estimate of COD value color of the standard reaction mixture based on a range of glucose concentrations can be used as a reference. For samples, with COD concentration of 300 to 500 mg/L, OD 585 or OD 635 can be recorded for obtaining more precise values. 
     
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 65 
               
             
             
               
                   
               
               
                 Tea + Apple Pomace + DWS (S3) + Glucose (ssp) 
               
               
                 Correlation between COD concentration, color of the reaction 
               
               
                 mixture and their OD at different wave lengths. 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Estimated 
               
               
                   
                 Sample 
                 Color of the 
                   
                 Estimated 
                 final COD 
               
               
                 COD 
                 dilution 
                 reaction 
                   
                 COD 
                 (mg/L) 
               
               
                 (mg/L) 
                 (Times) 
                 mixture 
                 OD 
                 (mg/L) 
                 (Col. 2 × 5) 
               
               
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 Values at OD 585 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.159 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.187 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.210 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace + DWS (S3) + Glucose (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                   
                 — 
                 &gt;10,000   
               
               
                   
                 10 
                  C2000 
                 0.359 
                 2000 
                  20,000# 
               
               
                   
                 50 
                 C400 
                 0.152 
                  417 
                 20,850 
               
             
          
           
               
                 Values at OD 635 nm 
               
               
                 Glucose: 
               
             
          
           
               
                 320 
                 NA 
                 C300 
                 0.142 
                 NA 
                 NA 
               
               
                 426 
                 NA 
                 C400 
                 0.167 
                 NA 
                 NA 
               
               
                 535 
                 NA 
                 C550 
                 0.189 
                 NA 
                 NA 
               
             
          
           
               
                 Sample: Tea + Apple Pomace + DWS (S3) + Glucose (ssp) 
               
             
          
           
               
                   
                 Nil 
                  C10000 
                   
                 — 
                 &gt;10,000   
               
               
                   
                 10 
                  C2000 
                 0.359 
                 2000 
                  20,000# 
               
               
                   
                 50 
                 C400 
                 0.152 
                  409 
                 20,450 
               
               
                   
               
               
                 #COD as deducible from Table 2 given in Example 2. 
               
               
                 D: Dark. 
               
               
                 T: Turbid. 
               
               
                 *OD out of range. 
               
               
                 NA: Not applicable. Samples are diluted to get an OD 585 in the range of 0.130 to 0.175 and OD 635 in the range of 0.120 to 0.160, to obtain a COD value in the range of 320 to 535 mg/L. (Based on the Tables 3 to 15 given in Examples 3 to 15). 
               
             
          
         
       
     
     The main advantages of the present invention are 
     1. The test can be carried out rapidly. 
     2. The test does not require any major instrument. 
     3. The test is very cheap. 
     4. The test requires very small amount of reagents. 
     5. The test is easy to perform. 
     6. The test can be done without the need for specially trained technician. 
     7. The test can be performed with the help of a kit also.