Patent ID: 6967104
Filing Date: 2005-11-22
Classification: G01N,Y10T

Abstract:
1. 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 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 about C100 to C10000 is achieved as shown in e) further diluting the sample with distilled water to obtain a COD range between about 320 to 535 mg/L wherein the dilution is determined according to Tables 1(a) & (b), f) mixing 1 mL of diluted sample from step (e), individually, with three reagents, consisting of 0.01 to 0.03 g mercuric sulfate per ml of standard glucose solution, 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 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 I) 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, all of said steps being conducted at room temperature.