bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen removal from digester supernatant via nitrite - SBR or SHARON?
Authors: Fux C. , Lange K. , Faessler A. , Huber P. , Grueniger B. , Siegrist H.
Published: May 2018

Separate biological elimination of nitrogen from the digester supernatant of a municipal wastewater treatment plant (WWTP) was investigated in pilot and full-scale plants. Denitrification mainly via nitrite was achieved in a sequencing batch reactor (SBR) and a continuous flow reactor (CSTR or SHARON). Suppression of nitrite oxidation in the SBR was feasible at short aerobic/anaerobic intervals allowing for immediate denitrification of the produced nitrite. Nitrate production could also be stopped by exposing the biomass to anaerobic conditions for 11 days. Temporarily high concentrations (up to 80 gNH3-Nm-3) of free ammonia could not be considered as the major reason for inhibiting nitrite oxidation. In a full-scale SBR plant 90% of the nitrogen load was denitrified in a total hydraulic retention time (HRT) of 1.6 days and with a sludge age between 15 and 20 days. Ethanol and methanol were used for denitrification. The specific average substrate consumption was 2.2 gCODdosedg-1Nremoved with an effective biomass yield of 0.2 gCODbiomassg-1CODdosed. No dosing with base was required. In the SHARON process full nitrogen elimination was achieved only with a total HRT greater than 4 days at 29°C. The overall costs were estimated at €1.4 kg-1Nremoved for the SBR and €1.63 kg-1Nremoved in SHARON mode, respectively. The SHARON process is simple in operation (CSTR) but the tank volume has to be significantly greater than in SBR.
Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by microbial consortia enriched from mangrove sediments
Authors: Tam N.F.Y. , Guo C.L. , Yau C. , Ke L. , Wong Y.S.
Published: May 2018

Surface sediments from two mangrove swamps in Hong Kong were enriched to obtain PAH-degrading microbial consortia. The consortium from sediments enriched with phenanthrene (Phe) in Ma Wan, a mangrove swamp next to a boat anchorage, was effective in degrading PAH with 96.7% and 89.9% Phe degradation at 0 and 10 ppt salinities, respectively. The Phe-enriched microbial consortium could also use pyrene (Pyr) as the sole carbon source but the degradation was much less (around 15%). On the other hand, the Phe-enriched consortium from sediments in Yi O, a mangrove swamp recently polluted by an oil spill, completely removed Phe and Pyr at both 0 and 10 ppt salinities. This suggests that different consortia were selected in two sediments using the same PAH substrate. Not only sediments, PAH substrate used for enrichment also selected different consortia. The Pyr- and Fla-enriched Yi O consortia only achieved 10.5 and 4.5% Phe degradation, respectively and the corresponding pyrene degradation was 7 and 40%. Among the three PAH compounds, fluoranthene (Fla) was most difficult to degrade, and 21.1, 11.3, and 36.8% Fla were degraded by Phe-, Fla- and Pyr-enriched cultures, respectively.
Solubilization of waste activated sludge by alkaline pretreatment and biochemical methane potential (BMP) tests for anaerobic co-digestion of municipal organic waste
Authors: Heo N.-H. , Park S.-C. , Lee J.-S. , Kang H.
Published: May 2018

Biochemical methane potential (BMP) tests have been carried out to determine the anaerobic digestibility of the waste activated sludge (WAS) and the sludge pretreated by NaOH (PWAS). The optimal NaOH dosage was determined to be 45 meq NaOH/L. The maximum SCOD solubilization was 27.7, 31.4 and 38.3% at the temperatures of 25, 35 and 55°C respectively after 4 hours reaction. The final methane yield of simulated food waste (SFW) was 430 ml CH4/g VSadded, and those of PWAS (25°C), PWAS (35°C) and PWAS (55°C) was 274, 286 and 310 ml CH4/g VSadded respectively after 20 days. The figures were 66%, 73% and 88% higher than that of WAS. The methane production in anaerobic co-digestion is considerably affected by the fraction of SFW and PWAS in the feed. The anaerobic digestibility of the feed mixture (SFW with PWAS) is higher than that of the feed mixture (SFW with WAS). Anaerobic co-digestion of food waste with the PWAS is found to be an attractive option to reduce the solid waste volume with improved methane recovery.
Groundwater pollution risk assessment methodology
Authors: Lytton L. , Howe S. , Sage R. , Greenaway P.
Published: May 2018

A generic groundwater pollution risk assessment methodology has been developed to enable the evaluation and ranking of the potential risk of pollution to groundwater abstractions. The ranking can then be used to prioritise risk management or mitigation procedures in a robust and quantifiable framework and thus inform business investment decisions. The risk assessment considers the three components of the pollution transport model: source - pathway - receptor. For groundwater abstractions these correspond to land use (with associated pollutants and shallow subsurface characteristics), aquifer and the abstraction borehole. An hierarchical approach was chosen to allow the risk assessment to be successfully carried out with different quality data for different parts of the model.

The 400-day groundwater protection zone defines the catchment boundary that forms the spatial limit of the land use audit for each receptor. A risk score is obtained for each land use (potential pollution source) within the catchment. These scores are derived by considering the characteristics (such as load, persistence and toxicity) of all pollutants pertaining to each land use, their on-site management and the potential for the unsaturated subsurface to attenuate their effects in the event of a release. Risk scores are also applied to the aquifer characteristics (as pollutant pathway) and to the abstraction borehole (as pollutant receptor). Each risk score is accompanied by an uncertainty score which provides a guide to the confidence in the data used to compile the risk assessment.

The application of the methodology has highlighted a number of problems in this type of work and results of initial case studies are being used to trial alternative scoring methods and a more simplified approach to accelerate the process of pollution risk assessment.
Review of operation of urban drainage systems in cold weather: water quality considerations
Authors: Marsalek J. , Oberts G. , Exall K. , Viklander M.
Published: May 2018

Cold climate imposes special requirements on urban drainage systems, arising from extended storage of precipitation and pollutants in the catchment snowpack, processes occurring in the snowpack, and changes in catchment surface and transport network by snow and ice. Consequently, the resulting catchment response and runoff quantity differ from those experienced in snow- and ice-free seasons. Sources of pollutants entering urban snowpacks include airborne fallout, pavement and roadside deposits, and applications of de-icing and anti-skid agents. In the snowpack, snow, water and chemicals are subject to various processes, which affect their movement through the pack and eventual release during the melting process. Soluble constituents are flushed from the snowpack early during the melt; hydrophobic substances generally stay in the pack until the very end of melt and coarse solids with adsorbed pollutants stay on the ground after the melt is finished. The impacts of snowmelt on receiving waters have been measured mostly by the snowmelt chemical composition and inferences about its environmental significance. Recently, snowmelt has been tested by standard bioassays and often found toxic. Toxicity was attributed mostly to chloride and trace metals, and contributed to reduced diversity of benthic and plant communities. Thus, snowmelt and winter runoff discharged from urban drainage threaten aquatic ecosystems in many locations and require further studies with respect to advancing their understanding and development of best management practices.
Investigation of potential surrogate organisms and public health risk in UV irradiated secondary effluent
Authors: Simpson D. , Jacangelo J. , Loughran P. , McIlroy C.
Published: May 2018

Watercare's Mangere Wastewater Treatment Plant in Auckland, New Zealand treats sewage from a population equivalent of approximately 1,000,000. The treatment plant is currently undergoing a major upgrade, and as a part of this upgrade the largest UV disinfection plant in the world (at the time of award of the contract) is being constructed.

Pilot scale investigations were undertaken at a purpose built facility. The pilot plant employed secondary treatment, sand filtration, UV disinfection and a number of low pressure membrane systems. Investigations at the facility focussed on attempting to identify relationships between potential surrogate indicator organisms (including enterococci, faecal coliforms, Clostridium perfringens spores and F-specific bacteriophage) and pathogenic organisms (including culturable human enteric viruses, bacterial pathogens and parasites).

The aim of the study was to identify a suitable indicator organism and an associated effluent concentration that would ensure that an acceptable level of public health risk was maintained in the environment.

The results showed that no suitable surrogate indicator organism could be found. However the results did indicate that a two tiered operating strategy, based on the concentration of enteroviruses present in raw sewage and an appropriate UV dose, would ensure that an acceptable level of public health risk was maintained in the environment.
The fate of estrogenic compounds in the aquatic environment: sorption onto organic colloids
Authors: Yamamoto H. , Liljestrand H.M.
Published: May 2018

In this study, sorption of some estrogens and estrogenic compounds onto several organic colloids was examined using fluorescence quenching techniques. Selected organic colloids included humic substances of several sources, Aldrich humic acid (AHA), Suwannee River humic acid (SRHA), Suwannee River fulvic acid (SRFA), and Nordic fulvic acid (NFA). Polysaccharides, alginic acid (AA) and dextran (Dex), and tannic acid (TA) were also selected. 17β-estradiol (E2), 17α-ethynylestradiol (EES), and estriol (E3) were selected as estrogens. Nonylphenol (NP), octylphenol (OP), and dibutylphthalate (DBP) were selected as estrogenic compounds. For most of the selected compounds, the sorption coefficients were in the order of TA > humic acids (SRHA or AHA) > fulvic acids (NFA or SRFA) > AA. The smallest or no significant sorption onto dextran was found for selected estrogens and estrogenic compounds. Comparing those compounds, neither a significant trend nor linear correlation with Log Kow was found. The resulting sorption coefficients for humic substances and TA suggested approximately 15 to 50% of the estrogens and estrogenic compounds were bound in typical natural water of 5 mgTOC/L and significant effects on the removal of them by water treatment processes, toxicity, or bioavailability were suggested.
Study of estrogenic effects on carp (Cyprinus carpio) exposed to sewage treatment plant effluents
Authors: Higashitani T. , Tamamoto H. , Takahashi A. , Tanaka H.
Published: May 2018

To investigate whether male carp (Cyprinus carpio) are really feminized by estrogen-like substances in effluent from sewage treatment plants (STPs) in Japan, exposure tests were performed using carp in water tanks that were receiving effluent from a STP. During eight weeks of exposure, we had measured their serum vitellogenin (VTG), a precursor of yolk protein specific for females that is synthesized in their liver by estrogen-like substances and that is, therefore, a biomarker of feminization. For this research, a STP with representative effluent estrogenic activity level was selected. In the first run of the tests that launched in the early spring of 2000, male carp were exposed. Results showed that the VTG concentration in male carp exposed to the effluent increased with time, while it was reduced after exposure to the effluents was stopped and the exposure was changed to dechlorinated tap water. On the other hand, in the control experiment, VTG was not detected in male carp exposed to dechlorinated tap water. Therefore, male carp might be reversibly feminized by the STP effluent. To assure whether the feminization of male carp was caused by the STP effluent at any time, two more runs of the test were performed in the summer of 2000 and February to April of 2001. However, significant level of VTG in male carp could not be observed for eight weeks. The estrogenic activities in the effluents were almost the same level throughout the tests; therefore the seasonal timing of exposure might be important for understanding this inconsistent phenomenon.
The behavior of estrogenic substances in the biological treatment process of sewage
Authors: Onda K. , Nakamura Y. , Takatoh C. , Miya A. , Katsu Y.
Published: May 2018

A study was conducted for about one year on the fate and behavior of estrogens, namely 17β-estradiol (E2), estrone (E1), and estriol (E3) in an activated sludge process of a pilot scale plant supplied with domestic sewage. A simultaneous analytical method for these three substances using LC-MS/MS was developed and applied to sewage samples. The average removal of E2 was 94.7%, while that of E3 was 96.9%. In contrast, the average removal of E1 was relatively low at 69.2% with a maximum concentration of 55.4 ng/L detected in the treated water. The theoretical values of estrogenic activity calculated from the concentrations of each natural estrogen in treated water were found to correlate with the values of estrogenic activity measured by a yeast estrogen screening assay. The effect of E2 on estrogenic activity in influent was found to be high, while that of E1 in treated water was considerably higher. In batch treatment tests on E2, E2 turned into E1 immediately after being charged. After three hours of aeration, the values of both E1 and E2 were around threshold limits. It was determined from this that E1 and E2 were substances that could be degraded by biological treatment. As the removal of E2 was found to be sufficiently high at times, optimization of operational conditions based on E1 removal should be important for reducing estrogenic activity in treated water.
Combined Fenton-MF process increases acrylonitrile removal
Authors: Chang C.-Y. , Wang C.-C. , Chang D.-J. , Chang J.-S.
Published: May 2018

The Fenton oxidation process is possessed of the advantages of both oxidation and coagulation processes. In addition to these functions, Fenton's reagent is also a typical initiator of polymerization. The application of the Fenton-microfiltration process for removal of acrylonitrile (AN), which is the major raw material for manufacturing ABS resins, was investigated. As for Fenton oxidation, in the range of pH 2 to pH 4, AN removal efficiency increased as the pH increased. In experiments of the same initial molar ratio of [FeSO4]0/[H2O2]0, the higher dosage can obtain the higher removal efficiency. At pH 4, the AN removal increased as the [H2O2]0 increased for each [FeSO4]0. Acrylic acid and acrylamide were detected in the solution after Fenton oxidation. On the other hand, acrylamide, polyacrylamide, and polyacrylic acid exist in the precipitate after the Fenton oxidation of AN solution. Moreover, It was also found that the operational mode is an important factor of the combined Fenton-MF process.
Removal of enteric viruses and selected microbial indicators by UV irradiation of secondary effluent
Authors: Jacangelo J.G. , Loughran P. , Petrik B. , Simpson D. , McIlroy C.
Published: May 2018

The Watercare Mangere Wastewater Treatment Facility, which treats wastewater from the greater Auckland New Zealand region, is undergoing a major expansion/upgrading to add advanced treatment and disinfection prior to discharge into a harbor. One important goal of this project is to protect the receiving water from microbial contamination. Since sufficient information on the fate of various microorganisms through wastewater treatment plants in New Zealand was not readily available, extensive pilot- and bench-scale studies were undertaken to develop specific design criteria for the treatment and disinfection systems. The specific objective of this study was to evaluate the removal and inactivation of enteric pathogens and other microbial indicators through treatment processes that employs UV irradiation as a final disinfection process. The removal of indicator organisms through secondary treatment was typically between 2.5-log (99.7% removal) and 2.8-log (99.8% removal) for fecal coliforms and enterococci, respectively. Indigenous F-specific bacteriophage exhibited a mean removal of 1.6-log (i.e. 97.7% removal) and Clostridium perfringens spores showed a mean removal of 1.3-log (i.e. 95% removal). The UV dose required to achieve a one log reduction in the concentration of indigenous F-specific bacteriophage was found to be approximately 20 mWs/cm2 per log removal. The concentration of enterovirus and adenovirus were consistently reduced to the limit of detection (1 TCID50/100L) at UV doses of 35 to 40 mWs/cm2 and 40 to 45 mWs/cm2, respectively. Clostridium perfringens spores were the most resistant indicator organisms, being reduced to less than 200 MPN/100 mL at a UV dose of 75 mWs/cm2.
Innovative reactor technology for selective oxidation of toxic organic pollutants in wastewater by ozone
Authors: Boncz M.A. , Bruning H. , Rulkens W.H.
Published: May 2018

Ozonation can be a suitable technique for the pre-treatment of wastewater containing low concentrations of toxic or non-biodegradable compounds that cannot be treated with satisfactory results when only the traditional, less expensive biological techniques are applied. In this case, the oxidation process has to be made as efficient as possible, in order to reduce the costs of ozone addition and energy use. An efficient oxidation process with ozone can be obtained by focusing the oxidation with ozone selectively on the direct oxidation of toxic pollutants and to minimize ozone losses due to the decay of ozone in water. Supported by data of the rate constants of the reactions involved, a mathematical model was developed. It quantifies the ozone consumption by the process, and the share of ozone consumption by undesired side reactions, in several different reactor systems. Results obtained with this model indicate that a plug flow reactor (PFR) will be the most efficient design for the oxidation reactor. As an alternative, the cascaded tank reactor system (CTR), in which the ozone feed may be realized with less practical problems, might be considered. The traditional continuous flow stirred tank reactor (CFSTR) is shown to be the least efficient system.
Lake Kinneret watershed contamination transports - a GIS based hydrological model
Authors: Ostfeld A. , Pries A.
Published: May 2018

This paper describes the efforts and current achievements of developing a GIS based hydrological model for flow and contaminants transport within Lake Kinneret watershed. The proposed model is built of hydrological “input-output” physical response blocks for routing rainfall-runoff water quantity and quality in sub-watersheds, coupled further with a delineated GIS database. An illustrative example of the model capabilities is demonstrated.
Optimum physical-chemical pre-treatment of copper damascene wastewater
Authors: Smith E. , Bayan M. , Daniels M.
Published: May 2018

Chemical and mechanical polishing (CMP) of copper damascene circuits will typically produce copper levels in excess of regulatory limits in wastewater with a unique process chemistry, including high solids. Physical-chemical methods were investigated to determine the optimum treatment depending upon pre-treatment and/or water reuse requirements. Jar test studies revealed that an alum dose of 150-200 mg/L together with anionic polymer aid provided a good removal of turbidity. If the treatment objective is simply solids and copper reduction for discharge to a sewer system, then solids removal can be combined with precipitation of copper hydroxide for relatively inexpensive pre-treatment. The presence of peroxide from the process solution, however, may make it difficult to achieve copper values below 5 mg/L, depending on the associated process conditions. If the objective is to remove solids and recover copper, which may also allow recovery of water for reuse, then solids removal by alum and polymer can be followed by ion exchange by a strong acid cation resin. As with precipitation, however, effective copper removal by ion exchange requires pre-treatment of peroxide by chemical reduction. The exchange of dissolved aluminum also reduces the capacity of the resin for copper.
Multiobjective water resources systems analysis using genetic algorithms - application to Chou-Shui River Basin, Taiwan
Authors: Kuo J.-T. , Cheng W.-C. , Chen L.
Published: May 2018

Multipurpose operation is adopted by most reservoirs in Taiwan in order to maximize the benefits of power generation, water supply, irrigation and recreational purposes. A multiobjective approach can be used to obtain trade-off curves among these multipurpose targets. The weighting method, in which different weighting factors are used for different purposes, was used in this research work. In Taiwan, most major reservoirs are operated by rule curves. Genetic algorithms with characteristics of artificial intelligence were applied to obtain the optimal rule curves of the multireservoir system under multipurpose operation in Chou-Shui River Basin in central Taiwan. The model results reveal that different shapes of rule curves under different weighting factors on targets can be efficiently obtained by genetic algorithms. Pareto optimal solutions for a trade-off between water supply and hydropower were obtained and analyzed.
Bisphenol A emission factors from industrial sources and elimination rates in a sewage treatment plant
Authors: Fuerhacker M.
Published: May 2018

Bisphenol A (BPA) is widely used for the production of epoxy resins and polycarbonate plastics and is considered an endocrine disruptor. Special in vitro test systems and animal experiments showed a weak estrogenic activity. Aquatic wildlife especially could be endangered by waste water discharges. To manage possible risks arising from BPA emissions the major fluxes need to be investigated and the sources of the contamination of municipal treatment plants need to be determined. In this study, five major industrial point sources, two different household areas and the influent and effluent of the corresponding treatment plant (WWTP) were monitored simultaneously at a plant serving 120,000 population equivalents. A paper producing plant was the major BPA contributor to the influent load of the wastewater treatment plant. All the other emissions from point sources, including the two household areas, were considerably lower. The minimum elimination rate in the WTTP could be determined at 78% with an average of 89% of the total BPA-load. For a possible pollution-forecast, or for a comparison between different point sources, emission factors based on COD-emissions were calculated for industrial and household point sources at BPA/COD-ratios between 1.4 ×10−6-125×10−6 and 1.3×10−6-6.3×10−6, respectively.
Low Flows 2000: a national water resources assessment and decision support tool
Authors: Young A.R. , Grew R. , Holmes M.G.R.
Published: May 2018

Information on the magnitude and variability of flow regimes at the river reach scale is a central component of most aspects of water resource and water quality management. However, many decisions are made within catchments for which there are no measured flow data. To meet this challenge, a suite of modelling techniques to assist in the estimation of natural and artificially influenced river-flows at ungauged sites has been developed. This paper summarises these models and how they are incorporated within the GIS framework of the Low Flows 2000 software package. The paper will also describe the implementation of Low Flows 2000 within England and Wales by the Environment Agency, and the use of the system in supporting the implementation of the Environment Agency’s Catchment Abstraction Management Strategy. This strategy is focused on the delivery of sustainable abstraction licensing and will contribute to the implementation of the Water Framework Directive within England and Wales.
The River Rhine as a source of micropollutants in the canal sediments of the city of Delft (The Netherlands)
Authors: Kelderman P. , Xuedong Y. , Wenchuan Q. , Drossaert W.M.E.
Published: May 2018

This paper presents a statistical analysis of the pollution levels for heavy metals and organic micropollutants at 182 sediment stations in the city canals of Delft. High pollution levels were especially observed in the inner city canal sediments, probably related to the import of polluted river Rhine water. In contrast, the more-or-less isolated outer city sites were generally much less polluted.

Regression analysis on the database generally showed highly significant correlations between individual heavy metal contents. The heavy metal contents were usually significantly correlated with polycyclic aromatic hydrocarbons (PAHs) as well. This points to one or more common sources for these micropollutants.

Factor analysis and the K-means cluster analysis technique were applied on the above database; it showed a large cluster of stations, nearly all located in the outer city of Delft, characterized by relatively low heavy metal and organic micropollutants’ contents. Another cluster of 18 stations, mostly located in the inner city of Delft, possessed intermediate pollution levels, directly related with the supply of river Rhine water. Finally, the stations of a third cluster, situated in the inner city as well, were highly polluted, especially by local pollution sources. The above hypotheses were further supported by a more detailed statistical analysis for a number of inner city stations, together with 10-year river Rhine pollution data.
Bleaching of bagasse pulp with enzyme pre-treatment
Authors: Sudha B. , Veeramani H. , Sumathi S.
Published: May 2018

The effluent from pulp bleaching processes containing chlorinated lignin and degraded polyphenolic intermediates remains as a major source of water pollution from the pulp and paper industries. Alternative elemental chlorine free bleaching methods based on the usage of chlorine dioxide, ozone and hydrogen peroxide are potential substitutes. Bio-bleaching methods, which involve pre-treatment of pulp with microbial enzymes such as xylanases, have emerged as viable options. Investigations reported in this paper aim at exploring the suitability of commercial bacterial xylanase enzyme preparations for bio-bleaching of bagasse pulps in conjunction with specific chemical bleach sequences employing hydrogen peroxide (P), alkali extraction (E), ozonation (Z), hypochlorite (H) and chelation (Q) stages. The effluent profiles and pulp qualities obtained for each of the bleach combinations (involving bio-bleaching and chemical bleaching sequences) were monitored. Analysis of the results clearly indicates that the inclusion of enzyme pre-treatment with the TCF (total chlorine free) and ECF (elemental chlorine free) sequences has a significant effect on the effluent (COD, lignin and colour) and pulp quality (kappa number, brightness) parameters. In conclusion, the findings of this investigation indicate the potential promise of enzyme pre-treatment in combination with chemical bleaching to enhance the quality of pulps and combined effluents.
Evaluation of the methods for first flush analysis in urban watersheds
Authors: Lee J.H. , Yu M.J. , Bang K.W. , Choe J.S.
Published: May 2018

The general tendency between the ratio of cumulative pollutant loads and the ratio of cumulative runoff appears as a nonlinear form which can be expressed in the form of a third polynomial. In this paper third degree polynomials were applied to represent the first flush curves based on the relationship between the cumulative pollutant load ratio and cumulative runoff ratio. The quantity of stormwater runoff and quality constituents, including chemical oxygen demand (COD), suspended solids (SS), total Kjeldahl nitrogen (TKN), ortho-phosphorus (PO4-P), total phosphorus (TP), n-hexane extracts (HEM), and iron (Fe) were analysed. The objectives of this study were (1) to characterize the quality of stormwater runoff (2) in order to analyse the cumulative curve area ratio and to calculate the first flush coefficients, (3) while also representing the first flush with a third polynomial equation.
Waste load allocation for water quality management of a heavily polluted river using linear programming
Authors: Cho J.H. , Ahn K.H. , Chung W.J. , Gwon E.M.
Published: May 2018

A waste load allocation model using linear programming has been developed for economic water quality management. A modified Qual2e model was used for water quality calculations and transfer coefficients were derived from the calculated water quality. This allocation model was applied to the heavily polluted Gyungan River, located in South Korea. For water quality management of the river, two scenarios were proposed. Scenario 1 proposed to minimise the total waste load reduction in the river basin. Scenario 2 proposed to minimise waste load reduction considering regional equity. Waste loads, which have to be reduced at each sub-basin and WWTP, were determined to meet the water quality goal of the river. Application results of the allocation model indicate that advanced treatment is required for most of the existing WWTPs in the river basin and construction of new WWTPs and capacity expansion of existing plants are necessary. Distribution characteristics of pollution sources and pollutant loads in the river basin was analysed using Arc/View GIS.
Nitrogen removal from water containing high nitrate nitrogen in a paddy field (wetland)
Authors: Nakasone H. , Kuroda H. , Kato T. , Tabuchi T.
Published: May 2018

Nowadays, it has become very common to find in Japan that nitrate nitrogen concentrations are very high in spring water and in well water where the land use of a watershed is agricultural. We have often observed around 50 mg/L of nitrate nitrogen in the spring water where we live. Crops produced in those fields are mainly vegetables such as celery, cabbage, lettuce, carrots, and so on. Green tea is also popular in Japan. In order to produce good quality green tea, farmers apply a great amount of nitrogen fertilizer. This amount can reach up to 1,000 kg/ha in some areas, although the average application amounts to 628 kg/ha in Japan. As a result, ground water that is rich in nitrate flows into the river, which results in a high nitrogen concentration in river water and ground water. Further, this causes a low pH in river water in some tributary rivers in Japan, though this kind of case is very rare. We knew from field tests that if water contained a high nitrogen concentration and was introduced into paddy fields, high nitrogen removal would be performed. This paper presents the outline and results of a system on how to remove nitrogen using paddy fields (wetlands). Further, this paper presents the evaluated results of the removal quantity at the watershed level.
Use of pH as fuzzy control parameter for nitrification under different alkalinity in SBR process
Authors: Peng Y.-Z. , Gao J.-F. , Wang S.-Y. , Sui M.-H.
Published: May 2018

In order to achieve fuzzy control of nitrification in a Sequencing Batch Reactor (SBR) brewery wastewater was used as the substrate. The effect of alkalinity on pH variation during nitrification was systematically studied, at the same time the variations of DO and ORP were investigated. Alkalinity and pH of the wastewater were adjusted by adding sodium bicarbonate at five levels and sodium hydroxide at two levels. Unadjusted wastewater was also studied. According to the results, variation of pH could be divided into rising type and descending type. When bicarbonate alkalinity was deficient or sufficient, the descending type happened. If alkalinity was deficient, the pH decreasing rate got slower when nitrification nearly stopped; if alkalinity was sufficient, at the end of nitrification pH turned from decrease to increase. This was the most common situation and pH could be used to control the end of nitrification. When alkalinity was excessive, the rising type happened, pH was increasing at nearly a constant rate during and after nitrification and could not be used to control the nitrification time, but if the aeration rate was moderate DO could be used to control the nitrification time. This situation seldom happened. Therefore the variation of pH could not only be used to control the nitrification time but also to judge whether the alkalinity was enough or not. On the basis of this, the fuzzy controller of nitrification in SBR was constructed. When discussing the influence of pH on nitrification rate the composition and concentration of alkalinity must be considered or else the results may be incomprehensive. And to some extent the influence of alkalinity on nitrification rate was more important than pH.
A thermal adaptation of bacteria to cold temperatures in an enhanced biological phosphorus removal system
Authors: Erdal U.G. , Erdal Z.K. , Randall C.W.
Published: May 2018

Temperature is one of the key parameters that affects the reaction kinetics and performance of enhanced biological phosphorus removal (EBPR) systems. Although studies agree regarding the effect of temperature on kinetic reaction rates, there are contradictory results in the literature regarding the effect of temperature on EBPR system performance. Early investigators (Sell, Ekama et al., Daigger et al.) reported better performance with lower temperatures, but others have reported partial or complete loss of EBPR functions at low temperatures (McClintock et al., Brdjanovic et al., Beatons et al.). One speculation is that deterioration in the EBPR system performance at cold temperatures can be attributed to rigid-like behavior of the cell membranes. Most cells (not all) on the other hand have the ability to alter their membrane fatty acid composition as temperature changes in order to keep their membrane at nearly the same fluidity despite the temperature changes. This unique ability is known as homeoviscous adaptation. In this study, homeoviscous adaptation by EBPR activated sludge was investigated for a series of temperatures ranging from 20°C to 5°C using a lab scale continuous flow EBPR system fed with acetate and supplemental yeast extract. The fatty acid analysis results suggested that the unsaturated to saturated fatty acid ratio increased from 1.40 to 3.61 as temperature dropped from 20 to 5°C. The increased cis-9-hexadecanoic acid (C16:1) at 5°C strongly indicated the presence of homeoviscous adaptation in the EBPR bacterial community. Thus the cell membranes of the EBPR community were still in a fluid state, and solute transport and proton motive force were operable even at 5°C. It was concluded that loss of EBPR performance at low temperatures is not related to the physical state of the cellular membranes, but is possibly related to the application of unsuitable operational conditions (low SRT, excessive electron acceptors, low anaerobic detention time, non-acclimated sludge, etc.).
Nitrification in biofilters under variable load and low temperature
Authors: Canler J.-P. , Perret J.-M. , Lengrand F. , Iwema A.
Published: May 2018

The evolution of European legislation has led to the rehabilitation of many wastewater treatment plants, sometimes through the installation of a biological complementary treatment stage. Among these sites, some plants in mountain areas are considering a biofiltration process. The design of such plants, especially for winter, appears to be tricky because of the very low influent temperature, the high performance requested for ammonia removal and the important and short term variations of the influent loads. The monitoring of a site during two consecutive winters has allowed us to study some aspects of the treatment. The major results are:•a maximal nitrification capacity of about 0.59 kg of formed N-NO3-.m-3 of material.d−1 with an influent temperature around 7°C at the plant inlet•a nitrifying biomass growth rate, expressed as nitrifying capacity increase, of 0.03 kg of N-NO3-.m−3 of material.d-2•quick and short terms load variations require a specific operation of the filters prior to the load increase, in order to grow enough active biomass to be able to treat the peak load immediately.
Investigation of oxygen transfer rates in full scale membrane bioreactors
Authors: Cornel P. , Wagner M. , Krause S.
Published: May 2018

In membrane bioreactors (MBRs) for wastewater treatment the secondary clarifier is replaced by a membrane filtration. The advantage of this process is a complete removal of solids from the effluent and a small footprint due to possible high biomass concentrations (MLSS). As oxygen supply counts for more than 70% of total energy cost in municipal WWTPs the design of the aeration system is vital for efficient operation. In this respect the a-value is an important influencing factor. The a-value depends on the MLSS-concentration as shown in various publications and confirmed by own measurements in two full scale municipal MBRs with MLSS ranging from 7 and 17 kg/m3. Furthermore it must be taken into account that a-values are not static values; they vary with loading rates, surfactant concentrations, air flow rates, MLSS concentrations, etc. The average a-value at typical 12 kg/m3 MLSS for municipal MBRs is about 0.6 ± 0.1. As submerged configured MBRs are equipped with an additional coarse bubble “crossflow” aeration system for fouling control, supplementary energy is consumed. Therefore MBRs need more energy compared to conventional treatment plants. Measurements of both aeration systems show that the fine bubble aeration system is more efficient by a factor of three concerning oxygen supply compared to the coarse bubble system.
Upgrading the Sjölunda WWTP according to a novel process concept
Authors: Hanner N. , Aspegren H. , Nyberg U. , Andersson B.
Published: May 2018

The Sjölunda wastewater treatment plant in Malmö, Sweden, was upgraded for extended nutrient removal in 1998-1999. The design was based on future effluent standards of 10 mg BOD7/l, 0.3 mg total-P/l and 8 mg total-N/l. The upgrading concept took into consideration existing processes and structures, resulting in a cost-effective and compact upgrading. To introduce nitrification, the existing trickling filters for BOD-removal were converted to a nitrifying mode. A sequencing batch reactor for nitrification of supernatant was necessary to control the ammonia load. Denitrification was accomplished in a moving bed biofilm reactor with addition of external carbon source. The future effluent standards could be met by the upgraded plant. The trickling filters were stable despite varying loading conditions. High rates and low effluent ammonia concentrations were achieved. Essential features for stable post denitrification were control strategies for carbon source dosage and avoiding phosphorus limitation.
Linking floc structure and settling properties to activated sludge population dynamics in an SBR
Authors: Govoreanu R. , Seghers D. , Nopens I. , De Clercq B. , Saveyn H. , Capalozza C. , Van der Meeren P. , Verstraete W. , Top E. , Vanrolleghem P.A.
Published: May 2018

Over a period of 227 days properties of activated sludge grown in an aequencing batch reactor (SBR) operated under stable conditions were analyzed. Settling properties (sludge volume index (SVI)) of the activated sludge were compared with on-line measurements of floc size and size distribution obtained by using a laser light scattering technique (Malvern Mastersizer/S, Malvern, UK), and with measurements of microbial community dynamics analyzed by denaturing gradient gel electrophoresis (DGGE) patterns of 16S rRNA genes. In addition, microscopical observations were used to confirm the results. Three distinct stages in the SBR evolution were observed. In the first stage the structural floc properties showed predominant presence of floc-forming bacteria in the activated sludge. A good correlation between floc size, settling properties and microbial community evolution was observed. The second stage showed a good balance between floc-forming and filamentous bacteria, with good settling properties and a highly dynamic community in the SBR. In the third stage, an increase in the filamentous bacteria, which became predominant in the system was observed. Again, a good correlation between settling properties and floc size distribution was obtained and a new dominant species was observed in the DGGE patterns, which can be assumed to be a filamentous organism.
An intelligent controller for automated operation of sequencing batch reactors
Authors: Cohen A. , Hegg D. , de Michele M. , Song Q. , Kasabov N.
Published: May 2018

In this paper the results are presented of original research into the automatic and “intelligent” detection of breakpoints in Dissolved Oxygen (DO) profiles. The research has been based on a large body of data collected from laboratory SBRs operating on synthetic wastewater. Two different approaches were followed to identify the endpoints. The paper analyses and evaluates the results of automatic breakpoint detection on the basis of geometric features in the DO profiles. This was followed by classification of the detected breakpoints using different soft computing techniques based on Neural Network (NN), Fuzzy Neural Network (FuNN) and Evolving Fuzzy Neural Network (EfuNN) software systems for breakpoint classification. A high rate of successful detection and classification was obtained with up to 96% of the decisions made correctly.

In order to overcome the limitations of this system to adapt to dynamically changing process conditions, an intelligent control model was developed by a combination between an Evolving Fuzzy Neural Net (EfuNN) combined with a logic decision unit. This system has the ability to “learn on-the-fly” and adjust its response pattern in order to maintain a high rate of successful breakpoint detection under varying changing process conditions.

This software system has been successfully embedded on a small programmable controller for integration into larger process control systems for the operation of SBR plants.
Performance and microbial dynamics in the coarse pore filtration activated sludge process at different SRTs (solids retention times)
Authors: Alavi Moghaddam M.R. , Guan Y. , Satoh H. , Mino T.
Published: May 2018

In this research, three SRTs (about 10, 30 and 75 days (without wasting the sludge except for sampling)) were applied to three reactors equipped with non-woven and coarse pore filter modules. The flux was adjusted to about 1 m/d during operation. The main objective of the study was to compare the performance and microbial population dynamics under different SRTs in this process. The results of reactors with SRTs of about 10 and 30 days have shown very good effluent quality without any clogging problem for more than 4 months of operation. For the reactor with long SRT (75 days), the filter clogging was observed after about 80 days of operation and caused an increase in the operation pressure and deterioration in effluent quality on some days. Excessive abundance of filamentous bacteria was observed in the reactor with SRT of about 10 days, which had the best effluent quality. According to the FISH results, type 021N was predominant in the reactor with long SRT, which had the clogging problem. On the other hand, other reactors (with SRTs of about 10 and 30 days) did not contain much type 021N, but some other filamentous bacteria dominated. Maximum EPS concentration (as mg/L) was observed in the reactor with long SRT. Also the abundance of two types of metazoa (Pristina sp. and tardigrades) was observed in the reactor with long SRT, which had the clogging problem and poor effluent quality.
Benchmarks for the energy demand of nutrient removal plants
Authors: Nowak O.
Published: May 2018

The energy demand of municipal wastewater treatment plants for nutrient removal equipped with primary clarifiers, activated sludge system, anaerobic sludge digestion, and CHP is evaluated theoretically, on the basis of COD balances. Operational experience from energy-efficient Austrian treatment plants confirms that the demand on external electrical energy can be kept as low as 5 to 10 kWh/(pe.a) depending on the N:COD ratio in the raw wastewater. A low N:COD ratio helps to keep not only the effluent nitrogen load low, but also the energy demand. Measures to minimise the energy demand at treatment plants and to reduce the nitrogen load are discussed.
Optimisation of Noosa BNR plant to improve performance and reduce operating costs
Authors: Thomas M. , Wright P. , Blackall L. , Urbain V. , Keller J.
Published: May 2018

Noosa WWTP is publicly owned and privately operated by Australian Water Services. The process includes primary sedimentation, raw sludge fermentation, biological nutrient removal (BNR), sand filtration and ultraviolet (UV) disinfection. An innovative feature of the plant is the supplementary carbon dosing facility to avoid the use of metal salts (alum or ferric) for phosphorus removal. The average flow treated during 2000 was 9.0 ML/d. The annual 50 percentile effluent quality requirements for nutrients are total N < 5 mg/L and total P < 1 mg/L. The objectives of this project were to: determine the cause of variability in phosphorus removal; develop a strategy to control the variability in phosphorus removal; and minimise the operating cost of supplementary carbon dosing while achieving the effluent quality requirements. An investigation of chemical and microbiological parameters was implemented and it was concluded that there were several factors causing variability in phosphorus removal, rather than a single cause. The following four major causes were identified, and the control strategies that were adopted resulted in the plant achieving annual 50 percentile effluent total P = 0.37 mg/L and total N = 3.0 mg/L during 2001. First, phosphorus removal was limited by the available VFA supply due to consumption of VFA by other organisms competing with phosphate accumulating organisms (PAO), and due to diurnal variations in the sewage VFA and phosphate concentrations. Therefore, supplementary carbon dosing was essential to make allowance for competing reactions. Second, increasing the fermenter VFA yield via supplementary carbon dosing with molasses was found to be an effective and economic way of ensuring reliable phosphorus removal. Third, nitrate in the RAS resulted in consumption of VFA by denitrifying bacteria, particularly with process configurations where the RAS was recycled directly into the anaerobic zone. Incorporating a RAS denitrification zone into the process rectified this problem. Finally, glycogen accumulating organisms (GAO) were observed in BNR sludge samples, and consumption of VFA by GAO appeared to cause decreased phosphorus removal. Better phosphorus removal was obtained using VFA derived from the fermenter than dosing an equivalent amount of acetic acid. It was hypothesized that GAO have a competitive advantage to use acetate and PAO have a competitive advantage to use propionate, butyrate or some other soluble COD compound in the fermenter effluent. Contrary to popular belief, acetate may not be the optimum VFA for biological phosphorus removal. The competition between PAO and GAO for different VFA species under anaerobic conditions requires further investigation in order to control the growth of GAO and thereby improve reliability of biological phosphorus removal processes.