bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance of a partly aerated biofilter in the removal of nitrogen
Authors: Chui P. C. , Terashima Y. , Tay J. H. , Ozaki H.
Published: May 2018

The removal efficiency of nitrogen and organic matter in an anoxic/aerobic upflow fixed bed filter was studied. Tests were carried out on the effects of aeration, hydraulic loading rate, and COD/N ratio on nitrogen removal and carbon oxidation. A synthetic high nitrogen concentration wastewater was used as substrate feed in the study. At an influent concentration of 250 mg N/L, and for volumetric loadings of up to 1 kg N/m3.day, between 41% and 86% of the nitrogen was removed. This was achieved without the recycling of effluent for denitrification. Nitrogen removal was possible when simultaneous denitrification took place inside the support media where oxygen was lacking. COD removal efficiency was consistently above 95% even at a high volumetric loading of 5 kg COD/m3.day and a bulk liquid dissolved oxygen level as low as 1.1 mg/L.
Evaluation of nitrogen removal by step feeding in large treatment plants
Authors: Görgün E. , Artan N. , Orhon D. , Sözen S.
Published: May 2018

Step feeding flow configuration is an attractive process alternative for large treatment systems designed for nitrogen removal, eliminating the need for internal recycling and optimizing organic carbon utilization for denitrification. Volume ratios of anoxic and aerobic volumes and wastewater fraction to be diverted from the inlet of the system are important parameters to be considered in the design of the step feeding process. Wastewater characterization and especially C/N ratio significantly affect the design. The effect of wastewater characterization is illustrated for the Riva Plant in Istanbul, with a capacity of 4 million population equivalent, designed as a two-stage step feeding system for biological nutrient removal. It is shown that the proposed design cannot meet the effluent standard of 10 mgl−1 total N for the relevant sewage characterization assessed on the basis of an extensive experimental study, totally different from the one adopted for design.
Evaluation of combined chemical and biological nutrient removal
Authors: Thomas P. R. , Allen D. , McGregor D. L.
Published: May 2018

This study was undertaken to optimise phosphorus removal by incorporating a chemical dosing facility in an existing biological nutrient removal activated sludge plant at Albury in Australia. Results of pilot plant trials and jar tests indicated that both alum and ferric chloride successfully reduced the orthophosphate concentrations with only a minor variation in the chemical costs. However, alum was chosen as the preferred chemical for use in the full-scale plant and tests showed that alum precipitation combined with biological nutrient removal lowered the orthophosphate (ortho-P) concentrations to as low as 0.01 mg/L with average total phosphorus (total-P) levels of around 0.5 mg/L. It is concluded that maximising total phosphorus removal in the treatment plant would require optimising biological phosphorus removal, applying correct chemical dosages to varying mixed liquor orthophosphate concentrations, adequate mixing, suitable pH values and minimising suspended solids in the clarifier effluent.
Removal of nitrogen and phosphorus using a new biofilm-activated-sludge system
Authors: Liu J. X. , van Groenestijn J. W. , Doddema H. J. , Wang B. Z.
Published: May 2018

This paper describes a laboratory scale experiment using a combined biofilm and activated sludge process to enhance biological nitrogen and phosphorus removal. In the system, fibrous carriers were packed in an anoxic tank for the attached growth of denitrifying bacteria and the sludge of the clarifier was returned to the anaerobic tank to release phosphate. In this configuration, nitrification, denitrification and phosphorus removal could be performed at their respective optimum conditions. The influent was domestic wastewater; the mean concentrations of COD, NH4-N and total phosphorus in the influent were about 319 mg/l, 60 mg/l and 10 mg/l respectively. At a total HRT of the system of 20-30 hours, based on the influent flow of the system, and a temperature of 10-15°C, the mean concentrations of COD, NH4-N, NO3-N, NO2-N and total phosphorus in the effluent were about 39.4 mg/l, 1.3 mg/l, 13.4 mg/l, 0.6 mg/l, and 0.8 mg/l respectively.
High nitrification rate with upflow biofiltration
Authors: Peladan J.-G. , Lemmel H. , Pujol R.
Published: May 2018

In order to investigate the upper limit of aerated biofilm processes, a series of experiments has been carried out on a pilot scale with a synthetic effluent containing only ammonium nitrogen and inorganic carbon as substrates. The influence of water velocity, air velocity and media height has been studied without the interaction of organic carbon and suspended solids. Under these conditions, the increase of the hydraulic load has a positive effect on the maximum nitrified load, despite the shortening of contact time. The pilot plant was able to nitrify 2.7 kg NH4+-N/m3.d at 14° C with an empty bed hydraulic retention time as short as 6 minutes - under a 30 m3/m2.h hydraulic load. It was also demonstrated that a cubic meter of granular bed presents the same nitrification capacity in a 3 m or in a 4 m media high biofilter, only if placed under the same conditions of air and water velocities. The results confirmed that water velocity significantly improves substrate bulk/biofilm transfer, and demonstrated that neither a contact time - based on the pore volume - as short as 2 minutes nor a media height of 4 m limit the nitrification rate.
Denitrification of groundwater using cotton as energy source
Authors: Volokita Michal , Abeliovich Aharon , Soares M. Inês M.
Published: May 2018

Microbial removal of nitrate from drinking water was studied in laboratory columns packed with unprocessed short fiber (low quality) cotton (Gossypium hirsutum). Cotton served as the sole chemical and physical substrate for the microbial population. Removal of nitrate was rapidly achieved without the formation of nitrite. Cotton (cellulose)-dependent denitrification was affected by changes in temperature: denitrification rates at 14°C were approximately half of the rates observed at 30°C. The cotton was entirely consumed in the process. In a fresh reactor, colonization of substrate by bacteria appears to be the rate limiting factor in the removal of nitrate.
Nitrogen removal from domestic wastewater using immobilized bacteria
Authors: Takizawa Satoshi , Aravinthan Vasanthadevi , Fujita Kenji
Published: May 2018

Two bench-scale Runs, namely Run A and Run B, have been investigated in order to study the effect of immobilized bacteria on denitrification in anoxic-oxic process. The hollow polypropylene pellets (O.D. 4 mm, I.D. 3 mm, nominal density 1.001 g/cm3) have been dosed into the anoxic reactor in Run A up to 24% of the volume. Run B was operated with no pellets in the anoxic reactor as a control experiment. Both Runs A and B contained the above pellets in the oxic reactor for a total volume of 24%. Run A showed superiority in nitrogen removal (73%) compared to Run B (65%) at a loading of 0.219 kgN/m3.d for a detention time of 4 hours at 15°C. By further investigating into the mechanism of nitrogen removal, it was concluded that the immobilized bacteria in the anoxic reactor in Run A enhanced not only the denitrification but also the ammonification that resulted in higher nitrogen removal efficiency.
A fast hydraulic numerical model for large sewer collection systems
Authors: Ji Zhong , Zdenko Vitasovic , Zhou Siping
Published: May 2018

A numerical model for simulating flows in either sewer or open channel systems is presented. The physical phenomenon of one-dimensional unsteady flow described by the St. Venant flow equations is examined for a more accurate and stable solution under a wide variety of physical conditions experienced in sewer or channel systems. A sparse matrix technique associated with a staggered grid numerical system is developed to solve the flow equations implicitly. Use of this sparse matrix technique leads to a substantial reduction in the order of the sparse matrix and the requirement of computer memory. The model is established without any omission of the terms in the St. Venant equations under the flow and depth conditions experienced in the sewer or open channel systems. The application of the model to a large complex looped sewer system shows that the model achieves a significant improvement in computational speed compared with the USEPA EXTRAN model and can still maintain similar accuracy. The model is especially suitable for real time control purposes since the simulation time of the model is almost negligible in comparison to the real time physical process even for a large looped system. The simulation also shows that base flow is practically not required for the model when the system is dry.
Characterisation of the performance of an off line storage tank
Authors: Huebner Martin , Geiger Wolfgang F.
Published: May 2018

A stormwater facility consisting of a hydrodynamic separator as an overflow device, an open concrete storage tank and two subsequent open earth retention basins was investigated. The results are used to characterise the qualitative performance of the storage tank. By evaluating the cumulative runoff volume and settleable solids load it is shown that the qualitative performance can be characterised by two effects: pollutants are retained because runoff is stored until the tank starts to overflow; pollutants are retained because the tank operates as a clarifier during the overflow period. The influencing factors on these two processes are discussed.
The contribution of domestic sources to levels of key organic and inorganic pollutants in sewage: the case of Melbourne, Australia
Authors: Wilkie Philip J. , Hatzimihalis George , Koutoufides Paul , Connor Michael A.
Published: May 2018

For the purposes of regulating discharges by industry to Melbourne's sewer network, information was needed on the concentrations of key pollutants in sewage from purely domestic sources. Sampling sites around Melbourne were identified where sewage free of trade waste contributions could be obtained. The sites chosen spanned a range of geographical areas and residential area types. Samples from these sites were analysed for a wide range of components. Similar analyses were conducted on samples from domestic water supplies. The consolidated results of these analyses are presented. The results show that the water supply contributes substantially to levels of many pollutants in domestic sewage. Comparisons with data for sewage plant influents show higher than expected inputs, from domestic sources, of many pollutants often regarded as having a mainly industrial origin.
Assessment of industrial waste loads in Istanbul watershed areas
Authors: Tünay O. , Germirli F. , Meriç S. , Orhon D. , Gönenç E.
Published: May 2018

Rapid population growth and industrialisation within metropolitan areas is a potential danger. The control of pollution in sensitive areas depends on the definition and control of sources. In this paper, results of the industrial source inventory and characterization study in the Istanbul watershed areas have been summarized. Emphasis has been given on industrial waste load assessment approaches and the methodology followed in the Istanbul watersheds has been given in detail and illustrated. Industrial loads are presented by industrial subcategory. Results of the study are evaluated and discussed.
Respirometry in control of the activated sludge process
Authors: Spanjers Henri , Vanrolleghem Peter , Olsson Gustaf , Dold Peter
Published: May 2018

This paper summarises progress of the IAWQ Task Group developing the Scientific and Technical Report (STR) on respirometry in control of the activated sludge process. The significance of respirometry in activated sludge systems is explained from a biochemical background. A classification is proposed which includes all respirometric measuring principles described in the literature. The different respiration rates that can be measured are reviewed and some variables that can be deduced from respiration rate are discussed. Some elementary control concepts will be provided that are necessary for the evaluation of respirometry-based control strategies. Finally, a number of respirometry-based control strategies will be classified and discussed.
Modified nernst model for on-line control of the chemical oxidation decoloring process
Authors: Chang Cheng-Nan , Lin Jih-Gaw , Chao Allen C. , Liu Chu-Sung
Published: May 2018

A modified Nernst equation was used to describe the decoloring reaction using the Oxidation-reduction potential (ORP) as an on-line monitoring and control parameter of the chemical reaction. In the modified equation, an “S” term is defined to indicate the oxidative potential (or decoloring potential) of dyes being studied. The laboratory study utilizes sodium hypochlorite (NaOCl) to reduce the color of wastewater spiked with textile dyes. Five dyes were used in preparing the wastewater samples: methyl red (MR), methyl violet (MV), methyl blue (MB), malachite green (MG) and methyl orange (MO). The color was measured by use of an automatic ADMI (American Dye Manufacturer Institute) measurement system in which a visible spectrophotometer was connected to a personal computer and the samples were scanned from 400 nm to 700 nm with a 10 nm interval each step. During the batch decoloring studies, several factors including ADMI, ORP, temperature and pH were continuously monitored with the computer. In this study, the potential of the decoloring compound of the dyes studies are in the following order: MG>MV>MO>MR>MB, with numeric ratios of 2.08 : 1.78 : 1.78 : 1.28 : 1.00, respectively.
Integration of wastewater treatment plant design and operation - a systematic approach using cost functions
Authors: Vanrolleghem Peter A. , Jeppsson Ulf , Carstensen Jacob , Carlsson Bengt , Olsson Gustaf
Published: May 2018

A general framework for the formulation and analysis of an overall decision support index is discussed. It is indicated that such an index allow evaluation of the combined effects of both design and operation (i) during the planning phase of new WWTPs, as well as (ii) for the evaluation of new operational strategies versus traditional expansions of plants already in operation. Attention is drawn to the problems of incorporating such factors as plant flexibility and robustness against failures in the index. These factors become especially relevant when decisions are to be made that affect the life span of a WWTP. Spatial and temporal separation of the optimisation problem are proposed to make the approach operational. It is not the intention of the authors to provide an exhaustive list of objective criterion functions, but rather to give the reader some examples illustrating the approach.
Surface active agents and their influence on oxygen transfer
Authors: Wagner Martin , Pöpel H. Johannes
Published: May 2018

Oxygen transfer rates of fine bubble aeration systems in uniform arrangement are reduced down to 40% to 70% in wastewater compared to clean water conditions. Surfactants in wastewater are the main reason for the inferior and therefore uneconomic performance. The influence of different types of surfactants (anionic and nonionic) and of their concentration on oxygen transfer is investigated at various properties of pure water (content of electrolytes, hardness) by means of extensive experiments.

The main results of the investigations are:in dependence of the type of surfactant, its concentration and the types of water:– the aeration coefficient kLa decreases (down to 55%)– the specific interfacial area (a) increases (up to 350%)– the oxygen transfer coefficient (kL) decreases (down to 20%)nonionic surfactants reduce the oxygen transfer more strongly than anionic surfactantsat the same surface tension, but different types of surfactant α-values can vary over a range of 0.12. Therefore α-values can not be calculated from surface tension measurementsα-values of approximately 0.55 should be taken for designing fine bubble aeration systemsIn new guidelines for the measurement of oxygen transfer rates, addition of 5 gm−3 of an arbitrary surfactant into clean water to simulate wastewater conditions must be abandoned.
Dynamic loading tests for final settling tanks
Authors: Baumer Patrik , Volkart Peter , Krebs Peter
Published: May 2018

Dynamic experiments conducted in a pilot scale settling tank at Zurich's wastewater treatment plant (WWTP) are presented. The experiments were carried out with real activated sludge. They showed that vertical perforated walls transverse to the main flow direction are very beneficial particularly for wet-weather flow. The increase of the effluent suspended solids concentration is significantly dampened with dynamic hydraulic loading. Installing several perforated walls enables uniform velocity profiles to be attained, enhancing flocculation. The total sludge mass stored in the final settling tank may be increased by this system and requires special attention when the removal system is designed.
Nocardia scum suppression technology by ozone addition
Authors: Okouchi T. , Goi M. , Nishimura T. , Abe S. , Murakami T.
Published: May 2018

In order to suppress scum formation due to Nocardioform Actinomycetes (Nocardia sp.), an experiment was made by adding ozone at a small rate in the aeration tank of the real plant in operation based on the oxygen activated sludge process. It was clarified that adding ozone at a rate of above 1.2 mg/l-raw water suppressed scum and Nocardia. The treated water quality was good, and no influence of ozone on the activated sludge was seen.
Testing of biological aerated filter (BAF) media
Authors: Kent T. D. , Fitzpatrick C. S. B. , Williams S. C.
Published: May 2018

The cost of filter media contributes a significant proportion of the initial capital outlay in wastewater treatment by biological aerated filters (BAFs). Media characteristics also affect day to day running costs such as those involved in backwashing. To allow an informed choice relating to filter media and their prospective uses a number of standards have been produced, most recently the British Effluent and Water Association (BEWA) standard. The aim of this study was to investigate a number of granular media using the BEWA standard in order to determine their suitability for BAFs. All the media samples investigated appear suitable for use as BAF media with one in particular having all the necessary characteristics e.g. low density, high specific surface area and resistance to attrition.
Effects of colloidal stability on clarification and dewatering of activated sludge
Authors: Mikkelsen L. H. , Gotfredsen A. K. , Agerbæk M. L. , Nielsen P. H. , Keiding K.
Published: May 2018

The effect of colloidal stability upon activated sludge properties for clarification and dewatering by filtration was investigated through controlled chemical manipulations of sludge in laboratory scale. The manipulations resulted in changes of the surface charge density and the shear sensitivity, the latter indicating a weakening of the sludge floc structure. The shear sensitivity was found to correlate with the residual turbidity after settling as well as with sludge filterability characteristics. The data strongly suggest the importance of blinding to increase with increasing shear sensitivity. The amount of fine particles present in the sludge was found to increase when sludge was exposed to a shear of similar magnitude to the shear in the employed filtration apparatus, indicating erosion of flocs during filtration to be important for blinding. Qualitatively similar results were obtained in full scale investigations of sludge from a treatment plant with varying inlet wastewater composition, indicating the possible importance of colloidal stability for solid/liquid separation processes in full scale wastewater treatment.
Settling and dewatering characteristics of sludge from baker's yeast production wastewater treatment
Authors: Arhan Y. , Öztürk I. , Çiftçi T.
Published: May 2018

The treatment of baker's yeast production wastewaters by a sequence of anaerobic and aerobic processes at the Pakmaya Izmit Plant results in the generation of three types of sludge, namely anaerobic, aerobic, and a mixture of the two. Formation of inorganic salts results in the accumulation of sludge in the bottom of the anaerobic reactors. Consequently, the volatile solids content of the sludges in the lower levels of the anaerobic reactors is lower. The higher levels of the anaerobic reactors are well mixed due to high circulation rate and biogas bubble rising. Settling and conditioning experiments were performed with all three types of sludge. The SVI values for all three types of sludge were low, indicating good settling characteristics. A high molecular cationic polyelectrolyte was found to be an effective conditioning chemical. Buchner Funnel Tests indicated that the SRF values for the anaerobic sludge were lower as compared to the aerobic sludge. The optimum dosage of the polymer for all three types of sludge was determined as 15 ml of 0.1% by weight solution per litre of sludge. Sludge thickening and dewatering with polymer conditioning have been applied successfully and economically on a full scale at the Pakmaya Plant using a combination of a rotary drum thickener and a belt filter, resulting in the production of sludge cake of 18–22% dry weight.
International moves towards standardisation of odour measurement using olfactometry
Authors: Schulz T. J. , van Harreveld A. P.
Published: May 2018

The general realisation that odour policy must be based on sound, scientific odour measurement techniques has resulted in recent major developments in olfactometry and its acceptance as a legitimate environmental assessment procedure. This article reviews progress in this field, in North America and Australasia, where policy tended to be based on the simple avoidance of nuisance around plants, and in Northern Europe, where the quantitative approach to odour policy has been more successful, with workable Europe-wide standards being developed. Extensive research and development, supported by interlaboratory testing programs, clearly demonstrated problems with repeatibility and reproducibility of testing results prior to 1995. This work identified the need for standardised olfactometry practices and better management of odour panel members. The widespread acceptance of forced choice dynamic olfactometry as the preferred measurement method is encouraging, although a practical internationally accepted standard for olfactometry will not be attained until testing results are ‘anchored’ to a standard reference material.
Inventories of point and diffuse sources and estimated nutrient loads - a comparison for different river basins in Central Europe
Authors: Behrendt Horst
Published: May 2018

A comparison of the estimated emissions (input) with the measured loads at monitoring stations (output) is presented for the large Rivers Rhine, Elbe and its main tributaries and for the River Warnow, a smaller river in the north-east part of Germany. The comparison shows that the discrepancies between the estimated emissions and the measured load is small for the Rhine and its main tributaries, Mosel, Neckar and Main. Large discrepancies were found for the Elbe and its main tributaries.

For all investigated river systems a strong relationship exists between the quotient of measured nutrient load versus the estimated sum of point and diffuse emissions of nutrients and the areal specific runoff. A function is derived for the dependency of the sum of retention and/or losses in a river system on the specific runoff and the nutrient concentration in the river. The high accuracy of the estimated retention and/or losses within the different river basins offer the possibility to use these equations for a prediction of the emitted nutrients from measured nutrient load in similar rivers.
A study on pollutant loads from the forest and rice paddy fields
Authors: Kawara Osami , Hirayma Katsuya , Kunimatsu Takao
Published: May 2018

The eutrophication of Lake Biwa, which is the largest lake in Japan and one of the most important fresh water resources, has been warned since 1960s. In order to improve the water quality of the lake, it is inevitable to reduce the pollutant loads from the river basins. The Hino river and the Soma river basins are considered in the present study and models which predict the influence of pollutant load generation on the discharged pollutant loads through the rivers. These basins mainly consist of forests and rice paddy fields. The identified models reproduce the observed water quality relatively well. Evaluation of loads from point-sources and non-point sources indicates that the loads from non-point sources occupy the most of pollutant loads from the basins. Especially, the loads from rice paddy fields occupy most of the pollutant loads from the basisn. Therefore, controlling non-point source pollutant loads in the Hino and Soma river basins is an important step in checking the eutrophication of Lake Biwa.
Effects of agricultural practices and vadose zone stratigraphy on nitrate concentration in ground water in Kansas, USA
Authors: Townsend M. A. , Sleezer R. O. , Macko S. A.
Published: May 2018

Differences in nitrate-N concentrations in ground water in Kansas can be explained by variations in agricultural practices and vadose-zone stratigraphy. In northwestern Kansas, past use of a local stream for tailwater runoff from irrigation and high fertilizer applications for sugar-beet farming resulted in high nitrate-N concentrations (12–60 mg L−1; in both soil and ground water. Nitrogen isotope values from the soil and ground water range from +4 to +8‰, which is typical for a fertilizer source. In parts of south-central Kansas, the use of crop rotation and the presence of both continuous fine-textured layers and a reducing ground-water chemistry resulted in ground-water nitrate-N values of < 3 mg L−1;. The effects of denitrification in the vadose zone and ground water are indicated by enriched δ 15N values of +10 to +15‰. At a site study, irrigated continuous corn was grown on sandy soils with discontinuous fine-textured layers. Here, nitrate-N concentrations were often > 10 mg L−1; in both soil and grounwater. Nitrogen isotope values of +3 to +7‰ indicate a fertilizer source. Crop rotation decreased nitrate-N values in the shallow ground water (9 m). However, deeper ground water showed increasing nitrate-N concentrations as a result of past farming practices.
Bioelements and heavy metals in dry and wet depositions at some localities in the morava river basin
Authors: Kocková E. , Palát M. , Betušová M.
Published: May 2018

Bioelements contained both in liquid and solid fall-out appear to be one of the potential sources of surface water pollution or effects on the landscape. The aim of the several-year monitoring consists in determining differences in the content of these components in particular localities of our region. To compare results, the methods of taking the samples as well as procedures in their processing were maintained although there are changes in the development and use of the methods. Due to technical reasons, it was not possible to separate liquid and solid components earlier than at two-month intervals. In spite of this, we use terms liquid and solid fall-out in determining the results although some small changes can occur in the liquid component. In comparing results of analyses from particular localities, it is necessary to take into account also the direction of prevailing winds which can help in identifying sources of air-borne components in fall-outs. All the fallout station localities were situated in such a way sources from the immediate vicinity to be eliminated. Sample analyses are aimed at general characteristics, i.e. dry matter, ash, water and macroelements (nitrogen, phosphorus, calcium, magnesium, sodium, potassium, iron, aluminium, manganese) and microelements (boron, zinc, molybdenum, copper, lead, nickel, chromium, cadmium and mercury). At present, the measurements continue and results obtained are processed.
Changes in measured biodegradation kinetics during the long-term operation of completely mixed activated sludge (CMAS) bioreactors
Authors: Ellis Timothy G. , Smets Barth F. , Magbanua Benjamin S. , Grady C. P. Leslie
Published: May 2018

Two completely mixed activated sludge (CMAS) bioreactors, one with an aerobic selector and one without, were operated for approximately twelve and sixteen months, respectively. Extant biodegradation kinetics for several compounds were periodically tested using a batch respirometric procedure. Kinetic parameters from the CMAS unit without a selector showed considerable variability (standard deviation of ± 50%) even though it was operated at steady state (i.e. constant HRT, SRT, organic loading, etc.) for the duration of the study. At first, there was a large discrepancy between the kinetic parameters of the two bioreactors. Phenol and 4-chlorophenol were biodegraded according to Monod kinetics in the selector system and Andrews (inhibitory) kinetics in the non-selector system, and the μ^ and KS values were significantly greater in the selector system. The kinetic parameter values of the two systems converged, however, when the xenobiotic compounds were no longer fed to the selector in that system but were fed to the main bioreactor. After this switch, phenol and 4-chlorophenol followed inhibitory kinetics in both systems. The lack of inhibition when phenol and 4-chlorophenol were fed to the selector suggests that, contrary to conventional wisdom, bioreactors which have a concentration gradient (e.g. plug flow, sequencing batch, and tanks in series bioreactors) may be more resistant to inhibition.
Characterization of the microorganisms from an acclimated activated sludge degrading phenolic compounds
Authors: Buitrón Germán , González Ariel
Published: May 2018

The microorganisms responsible for the degradation of a mixture of phenol, 4-chlorophenol (4CP), 2,4-dichlorophenol (24DCP) and 2,4,6-trichlorophenol (246TCP) were isolated and characterized in terms of its degradation rate. Activated sludge was acclimated for 70 days to 40 mg phenols/l. After this period the microorganisms responsible for the chlorinated phenol degradation were isolated and identified. Four types of Gram negative bacteria (Aeromonas sp., Pseudomonas sp. Flavimonas oryzihabitans, and Chryseomonas luteola) and Mycobacterium sp. were identified. The degradation kinetics of each phenol by Aeromonas sp.,Pseudomonas sp. Flavimonas oryzihabitans, Chryseomonas luteola and activated sludge were determined. The degradation of phenolic compounds was sequential: phenol and 4CP were first degraded, following by 24DCP and then by 246TCP. The acclimated activated sludge was from one to two orders of magnitude faster than the pure strains, when uptake rates were calculated in terms of the viable biomass (CFU). The qx for acclimated activated sludge varied between 8.2 and 15.8 × 10−7 mg/CFU-d (407–784 mg/gVSS-d). Aeromonas sp. presented the highest qx of the pure strains, based on a VSS basis (33–57 mg/gVSS-d) but, in terms of viable biomass (5.0–15.6 × 10−8 mg/CFU-d) Pseudomonas sp. did. Specific substrate uptake rate was 1.8 mg chlorinated phenols/g VSS-d for non-acclimated activated sludge.
Biotransformation of nitrocellulose under methanogenic conditions
Authors: Freedman David L. , Caenepeel Bryan M. , Kim Byung J.
Published: May 2018

Treatment of wastewater containing nitrocellulose (NC) fines is a significant hazardous waste problem currently facing manufacturers of energetic compounds. Previous studies have ruled out the use of biological treatment, since NC has appeared to be resistant to aerobic and anaerobic biodegradation. The objective of this study was to examine NC biotransformation in a mixed methanogenic enrichment culture. A modified cold-acid digestion technique was used to measure the percentage of oxidized nitrogen (N) remaining on the NC. After 11 days of incubation in cultures amended with NC (10 g/L) and methanol (9.9 mM), the % N (w/w) on the NC decreased from 13.3% to 10.1%. The presence of NC also caused a 16% reduction in methane output. Assuming the nitrate ester on NC was reduced to N2, the decrease in CH4 represented almost exactly the amount of reducing equivalents needed for the observed decrease in oxidized N. An increase in the heat of combustion of the transformed NC correlated with the decrease in % N. There was no statistically significant decrease in % N when only NC was added to the culture, or in controls that contained only the sulfide-reduced basal medium. The biotransformed NC has a % N comparable to nonexplosive nitrated celluloses, suggesting that anaerobic treatment may be a technically feasible process for rendering NC nonhazardous.
Anaerobic degradation of pentachlorophenol (PCP) in biological expanded-bed reactor
Authors: Tsuno Hiroshi , Kawamura Masasumi , Somiya Isao
Published: May 2018

In this study, anaerobic degradation of PCP was discussed in an expanded-bed GAC anaerobic reactor which was applied to treatment of wastewater containing high concentration of PCP-Na as well as acetate. Total-COD concentration in effluent was kept less than 100 mg/L except for the start-up duration and PCP-Na concentration was kept less than 0.50 mg/L under the experimental conditions (HRT of 5 days, influent PCP-Na concentration of 100 and 400 mg/L, and influent Total-COD concentration of 480 and 1600 mg/L). It was indicated by methane production rate and material balance of PCP-Na that about 60% of PCP-Na loaded into the reactor was transformed to methane and CO2 for 375 days. GC/MS analysis of extracts of the GAC medium and effluent indicated that reductive dechlorination of PCP occurred and dechlorinated phenols were adsorbed on the GAC in the reactor. Microorganisms collected from the reactor degraded PCP-Na and 2-CP anaerobically and addition of acetate in culture accelerated anaerobic degradation of PCP-Na in batch experiments.
Numerical model of biofilm kinetics in a methanogenic fluidized bed
Authors: Imai Tsuyoshi , Kusuda Tetsuya
Published: May 2018

A layered biofilm model which expresses the growth process of biofilm with attrition in a methanogenic fluidized bed reactor is developed based on results of experiment to comprehend distributions of biomass in the biofilm. Availability of the model and the existence of “dormant” biomass in the biofilm are discussed in comparison with the experimental results. Distributions of the active, dormant, and inert biomasses and extracellular polymer in a biofilm are predicted by the model. Comparing specific activities of sloughed and remaining biomasses with those of the attached biomass, the existence of “dormant” biomass in the biofilm is indicated. The model also expresses distributions of specific activities of active and dormant biomasses in the biofilm with high accuracy. The model is applicable to predict the distributions of biomasses in a biofilm under various sloughing conditions.
Experience with UASB reactor start-up under different operating conditions
Authors: Ghangrekar M. M. , Asolekar S. R. , Ranganathan K. R. , Joshi S. G.
Published: May 2018

Four laboratory upflow anaerobic sludge blanket (UASB) reactors were operated at different operating parameters viz., hydraulic retention time (HRT), upflow velocity, organic concentration, and Ca2+ concentration in the wastewater. These operating parameters gave different values of organic loading rates (OLRs) and sludge loading rates (SLRs). The reactor performance during start-up was evaluated at different values of the above listed parameters. Also, the effects of these parameters on the granule characteristics were investigated.

It was observed that COD removal efficiency at steady state was profoundly influenced by SLR. The reactor started with SLR of 0.6 kgCOD/ kg VSS.d could result in about 50% COD removal at steady state. The reactor performance could not improve even after three months of operation. Up to 0.3 kgCOD/ kgVSS.d the reactor performance was good with more than 90% COD removal at steady state. The OLD and SLR also determine time required for the reactor to achieve steady state.

Different operating conditions also have the bearing on the strength of the granules cultivated. The methanogenic activity measured on acetate for each reactor was observed between 0.259 and 0.909 kg CH4 COD/ kgVSS.d. The sludge production in all the reactors was between 0.087 and 0.13 kgVSS/ kgCODin. The mathematical model was developed in order to predict sludge production.
Microbicidal effect of reflected UV radiation in devices for water disinfection
Authors: Sommer R. , Cabaj A. , Haider T.
Published: May 2018

A standardised biodosimetric method was used to quantify the influence of reflection on the reduction equivalent UV doses (RED) in two commercially available water disinfection systems. One device, possessing a reflector made of aluminium, showed a decrease of RED of about 40% after removing the reflector. In the other plant, made of stainless steel, the inner surface of the irradiation chamber served as a reflector by itself. After eliminating the reflectance by black lacquering the inner surface of the irradiation chamber a distinctive decrease of RED was measured. This effect depended on the transmittance of the water (253.7 nm). With increasing water transmittance an increasing relative loss of RED was observed.

The results showed that the relative extent of the RED caused by reflection may even exceed the reflectance of the material due to multiple reflection, especially in water with high transmittance. However, in UV disinfection plants with inner surfaces made of reflecting material the reflectance may decrease during the operating life. Therefore, measuring the extent of reflection influencing the RED by using a suitable biodosimetric method is essential in UV devices for water disinfection.
The uptake of inorganic phosphorus by insoluble metal-humic complexes
Authors: Petrovic Mira , Kastelan-Macan Marija
Published: May 2018

Interaction and binding of dissolved orthophosphate on insoluble complexes of marine humic substances and calcium, magnesium, iron and aluminium have been studied. The results pointed out that solubility of metal-humic and fulvic complexes increases as the pH of the suspension increases with strong phosphorus fixation at pH-values between 4 and 6. The possible mechanism of this binding involves formation of a complex association in which metal ions bound to the humic substances act as a bridge between humic macromolecules and phosphate anion.
An overview of the management of contaminated sites in the US: the conflict between technology and public policy
Authors: Kavanaugh M. C.
Published: May 2018

Since the late 1970s, the US has utilized a variety of strategies to manage the problem of contaminated land and groundwater within the 50 states, a problem whose dimension is still not well defined. Recent estimates indicate that the US may spend up to 1 trillion dollars over the next 20 to 30 years undoing the environmental damage caused by improper storage and disposal of hazardous materials and toxic wastes over the past several decades, but predominantly since the end of World War II. Whether these expenditures will provide an equivalent level of benefit or risk reduction to US citizens is a subject of current debate. The effective management and remediation of this complex array of sites is proving both difficult and expensive. Research over the past decade has shown that in many cases, technology is limited in its ability to restore contaminated sites to pre-industrial conditions. In the US, new policy initiatives are being developed that insure both protection of human health and the environment, but at significant reduction in life cycle costs to society. Risk-based decision making is replacing rigid politically driven remediation decisions. The changes in the US model for management of contaminated sites provides valuable insights to other nations who are or will be faced with the same difficult choices balancing the costs of remedial strategies against potential reduction in risks to human health and the environment.
Catalytic effects of high Fe(III) concentrations on Fe(II) oxidation
Authors: Tüfekci N. , Sarikaya H. Z.
Published: May 2018

Catalytic effect of the ferric hydroxides on the oxidation of ferrous iron by aeration has been demonstrated and the kinetics of this catalytic reaction has been formulated by the recent studies. It has been reported that the oxidation rate is linearly increasing with Fe(III) concentrations up to 100 mg/l.

In this study, the oxidation of Fe(II) is studied in batch reactors in which the concentration of Fe(III) was in the range of 0-600 mg/l. A quadratic equation has been given to determine the catalytic reaction rate constant as a function of Fe(III) concentration. It was experimentally demonstrated that there was no significant effect of Fe(III) on the ferrous iron oxidation at Fe(III) concentrations beyond 600 mg/l.
Twenty-five years of wastewater reclamation in windhoek, Namibia
Authors: Haarhoff Johannes , Van der Merwe Ben
Published: May 2018

In 1968, a direct water reclamation system from domestic sewage was pioneered in Windhoek, Namibia, to supplement the potable water supply to the city. This system went through a succession of modifications and improvements over the years, but consistently produced water of acceptable quality, as evidenced a comprehensive chemical, bacteriological, virological, and epidemiological monitoring. Now, in 1995, Windhoek is again facing a shortfall of potable water in the light of a population increase (growing at 6% to 8% per annum) and increasing water demand, and is currently extending the water reclamation system from the previous 4800 to 21000 m3.d−1, the maximum attainable. All the components of the reclamation system are being reviewed and re-analyzed; demand management, diversion of some industrial effluents, wastewater treatment, water reclamation, oxidation and adsorption technologies, blending of reclaimed wastewater with other sources, buildup of salinity, treatment costs, and monitoring and quality control strategies. The practical experience at Windhoek demonstrates that a direct wastewater reclamation system is a practical, responsible way of augmenting potable water supplies in arid regions, but that it requires comprehensive planning, training and on-going commitment for its continued success.
Area-wide use of reclaimed water in Tokyo, Japan
Authors: Maeda Masahiro , Nakada Kiyomi , Kawamoto Kazuaki , Ikeda Masataka
Published: May 2018

In Japan, wastewater treatment plants generate 1.09 × 1010 m3 of effluent in a year. 8.5 × 107 m3 of it is reused. Several criteria have been proposed for reclaimed water quality. However there is not national standards yet. In this paper, reclaimed water use in Japan is briefly described. Existing quality criteria are also presented. In the context of reclaimed water use, Tokyo is one of the cities which have promoted the reuse of treated effluent. Especially, stream restoration project and area-wide water recycling projects are epoch-making projects. In this paper, area-wide water recycling project in Shinjuku district which is one of sub-centers in Tokyo is described. In this project, reclaimed water is used for toilet flushing in 19 high-rise buildings. Construction cost, funding and user charges are also given.
Rouse Hill – Australia's first full scale domestic non-potable reuse application
Authors: Law Ian B.
Published: May 2018

There has been increasing interest in reuse of effluent from sewage treatment plants in Australia in recent years, not only for agricultural or land irrigation purposes but also for the provision of dual water supplies to residential areas for the non-potable purposes of toilet flushing, car washing, garden watering and park or other open space irrigation. The Rouse Hill development in the north west of Sydney is Australia's first full scale application of domestic non-potable reuse, with the sewage treatment plant and the dual water distribution system being commissioned in late 1994. This paper describes the Rouse Hill project as a whole including the reasoning behind the installation of the dual water supply system, the design of the sewage treatment plant, the effluent qualities achieved, the design of the dual water distribution system and the requirements of the regulatory authority, the NSW Environmental Protection Authority.
Wastewater effluent reuse by in-line flocculation filtration process
Authors: Cikurel Haim , Rebhun Menahem , Amirtharajah Appiah , Adin Avner
Published: May 2018

Granular media filtration is an important treatment process for various reuse applications. Size density, and attachment strength of filter deposits produced by the interaction of effluents with alum, alum-polymer aids and cationic polymers as primary flocculants and the filter media during contact filtration were calculated and compared using existing filtration models. Secondary effluent filtration without flocculant addition was relatively ineffective. Effective alum dose for contact filtration ranges 10 - 20 mg/L. The 10 mg/L is superior, while the latter creates bulky deposit. An addition of 0.05 - 0.1 mg/L of low anionic high molecular weight polymer strengthens the alum-particle bond. Grain size influence seems to be more pronounced at low approach velocities (5-10 m/hr). High cationic, medium to high molecular weight polymers performed equally or better than alum as primary flocculants. High molecular weight cationic polymer-effluent particle deposit has a higher attachment strength than that of the alum, resulting in a smaller detachment with increase of velocity or increase of filtration run length. Cationic, high molecular weight polymers are effective at doses as low as 0.5 mg/L, at different charge densities. High cationic, medium molecular weight polymers are effective at doses > 5 mg/L. The pressure gradient increase and the filtration efficiency is proportional to the polymer dose in the (1-7 mg/L) range. Compared to the high molecular weight polymer, the pressure build up is milder. High cationic, low molecular weight polymers are not effective at doses up to 7 mg/L. The pressure build up is slow following a slow ripening. In high particle loadings, the differences among the various treatments are less pronounced.
Multi-species plant systems for wastewater quality improvements and habitat enhancement
Authors: Karpiscak Martin M. , Gerba Charles P. , Watt Pamela M. , Foster Kennith E. , Falabi Jeanne A.
Published: May 2018

The use of macrophytic plants for the treatment of municipal wastewater is growing rapidly. The Constructed Ecosystems Research Facility (CERF) is a joint project of the Pima County Wastewater Management Department and The University of Arizona's Office of Arid Lands Studies. The facility consists of five 30-mil-hyperlon-lined raceways measuring 61 m long, 8.2 m wide, and 1.4 m deep and one slightly larger raceway. Research has been and is being conducted with aquatic plants such as water hyacinth (Eichhornia crassipes), duckweed (Lemna spp.), giant reed (Arundo donax), bulrush (Scirpus olneyi), black willow (Salix nigra), and cottonwood (Populus fremontii). Composite water samplers are used to collect refrigerated samples from incoming secondary wastewater from Pima County's Sewage Treatment Facility and from the effluent leaving each raceway. Water samples have been analyzed for parameters such as pH, BOD5, and total nitrogen. Microbiological studies have concentrated on the removal of indicator coliform bacteria, as well as Giardia, Cryptosporidium and viruses from the wastewater. Data from the water quality studies indicate that these constructed ecosystems reduce BOD5 consistently to below the 10 mg/L BOD5 tertiary standard, remove nitrogen as well as decrease the concentration of pathogens significantly.