bluuebunny/crossref_metadata_2025 huggingface dataset:
A process engineering approach to water and wastewater treatment education
Authors: Stephenson Tom
Published: May 2018

Development of more stringent water quality standards has been met with development of more sophisticated processing. It is argued that the skills and knowledge of the process engineer are now required to design, operate and manage treatment plants of today. The postgraduate degree courses run by the School of Water Sciences adopt a process engineering approach, giving students a fundamental understanding of unit operations before applying them in the context of the flowsheet. This is achieved by having three parts to a course: a taught element for fundamental skills and knowledge; group design projects for applications of unit operations in flowsheets; and a practical thesis project for application of novel unit operations. Industrial lecturers, groupwork and oral presentation of work helps develop skills relevant to future careers in water and wastewater treatment.
Semi-technical investigations into the removal of nitrogen and phosphorus at the kleve-salmorth waste water treatment plant
Authors: Bäumer Karl Arno , Baumann Angela
Published: May 2018

The Institute for Water and Waste Management (ISA) at the Aachen University of Technology (RWTH) verified, through semi-technical analysis, the efficiency of the planned upgrade of the Kleve-Salmorth waste water treatment plant. Additionally the allowable biological phosphorus removal limit and the scheduled simultaneous precipitation were also ascertained.
Short horizon control strategies for an alternating activated sludge process
Authors: Isaacs S.
Published: May 2018

Three control strategies allowing improved operational flexibility of an alternating type activated sludge process are presented in a unified model based framework. The control handles employed are the addition rate of an external carbon source to denitrification, the cycle length, and the dissolved oxygen level during aerobic periods. All three strategies attempt to satisfy a common control criterion representing optimal performance over the time length of one process cycle (typically 1 to 3 hours) and are based on models developed from simple mass balances or which have been experimentally determined. The effects of the strategies on short term nitrogen dynamics are explained in terms of the potential and capacity of denitrification. The relative effectiveness of the strategies are compared and where the strategies would be located in a hierarchical control structure is discussed.
Biosensors for nitrogen control in wastewaters
Authors: Massone A. G. , Gernaey K. , Bogaert H. , Vanderhasselt A. , Rozzi A. , Verstraete W.
Published: May 2018

The control of nitrogen removal processes in activated sludge systems requires not only on-line values of the parameters such as ammonium, nitrate and nitrite, but also an evaluation on the nitrifying and denitrifying biomass activity, influent toxicity and carbon source requirements for denitrification. This paper describes four different biosensors, two on denitrification and two on nitrification. They all measure the biological activity of the nitrifying or denitrifying bacteria. Three of them measure nitrogen and carbon species, the fourth biosensor measures influent toxicity. These instruments open new perspectives for efficient on-line monitoring of wastewater treatment plants.
The effect of residual substrate utilization on sludge settling in an enhanced biological phosphorus removal process
Authors: Chang W. C. , Chiou R. J. , Ouyang C. F.
Published: May 2018

The simultaneous process requirements of phosphorus removal and bulking control were demonstrated in this study via a unified explanation along with an introduction of the parameter qre, i.e., specific residual substrate utilization rate. Pilot-plant experiments using synthetic wastewater were performed at different SRTs (5, 10, 15) and anaerobic:aerobic volume ratios, Van:Va (1:9, 1:4, 1:2.3). These results indicated that more than 75% of phosphorus removal and 94% of COD removal can be achieved during experimental periods. However, sludge settling properties in terms of SVI varied significantly, and a higher phosphorus removal did not necessarily imply a better sludge settling. Nevertheless, SVI-values highly correlated with qre - regardless of different SRTs and Van:Va ratios. This correlation would imply that the specific utilization of residual substrate left for filaments in oxic zone is the primary factor influencing SVI. Furthermore, eliminating the access of filaments to substrate plays a more influential role on SVI than favouring the poly-p microorganisms : the main floc-formers in EBPR process. Based on these findings we can infer that when in the design and/or operation stage of the EBPR process, the carbon sequestration by poly-p microorganisms in anaerobic zone can be as much as possible so as to obtain a lower qre in the oxic zone. That is, if phosphorus removal and bulking control is achieved simultaneously.
The importance of the treatment plant performance during rain to acute water pollution
Authors: Rauch W. , Harremoës P.
Published: May 2018

Rain causes not only pollution loads from combined sewer overflows but also from treatment plants. High hydraulic load conditions can affect the secondary clarifier performance, resulting in a massive loss of sludge from the plant. The consequence to the oxygen concentration in the recipient can be described by the same simplified mechanism, because the principle remains the same. The difference that has to be accounted for, is the different organic characteristics of the discharged water. The analysis of a hypothetical urban drainage system by means of a deterministic model reveals the importance of the treatment plant in this respect. Oxygen depletion in urban rivers is caused by intermittent discharges from both sewer system and wastewater treatment plant. Neglecting one of them in the evaluation of the environmental impact gives a wrong impression of total system behavior. Linear sensitivity analysis provides useful information for water quality management. The significant parameters in terms of acute water pollution are identified.
Solids routing in an activated sludge process during hydraulic overloads
Authors: Kim Youngchul , Pipes Wesley O.
Published: May 2018

In order to provide a quantitative description of solids wash-out from the settling tanks of an activated sludge process, a method for “routing” of the suspended solids through the settling tanks was developed. The objective was to develop a method which can be used to predict the mixed liquor suspended solids concentration (X) and the sludge blanket depth (SBD) in the clarifiers during transient hydraulic overloads. There were 27 individual hydraulic overloading events encountered during 31 months of study. The solids routing and the SBD prediction were performed for the individual storm flow events by using settling tank operating data. The results of solids routing analysis were found to be satisfactory. The mixed liquor solids concentration can be predicted within ± 10%. The application of a solids storage relationship developed for the settling tanks was found to be useful for describing the dynamic behavior of the SBD during transient hydraulic overloads. The solids wash-out predictions for rainstorm periods corresponded with the plant performance. Operational procedures for avoiding solids wash-out are also discussed.
Modified platinum electrodes: electrochemical characteristics and behaviour in activated sludge
Authors: Héduit Alain , Quinio Isabelle , Stadmuller Daniel , Thévenot Daniel R.
Published: May 2018

Polished platinum electrodes were coated with platinum black and/or with organic polymers (Nafion, polyurethane) to accelerate the electron transfer rate to the metal-solution interface and/or to constitute a protection barrier for the metal against neutral or anionic contaminants present in wastewater. The modified electrodes were electrochemically characterized (surface roughness and exchange current density) and their behaviour in activated sludge was studied. A platinum black deposit increases the roughness and the exchange current density. However, the response of these electrodes in an anoxic environment is very slow, which results in a low variation amplitude of the potential when they are placed in activated sludge alternately submitted to sequences of aeration and anoxia. A Nafion film provides partial protection against contaminants thus increasing electrode response reproducibility. A polyurethane film has no apparent protective effect.
Biological treatment of municipal wastewater with deep tanks and flotation for secondary clarification
Authors: Gnirss R. , Peter-Frölich A.
Published: May 2018

For municipal wastewater treatment, space-saving 10m deep activated sludge tanks are an interesting alternative to conventional tanks of shallow construction. Results from pilot tests in the Berlin-Ruhleben WWTP have shown that the biological P--elimination, nitrification and denitrification processes can be implemented with the same sucess as in shallow tanks. However, the activated sludge did not settle satisfactorily. Flotation was implemented in the process for secondary clarification and has been shown to be advantageous. Tests run over a period of some years with the pilot plant have proven the feasibility of this process. Energy requirements for both systems were found to be approximately the same. A cost estimate based on a preliminary plan revealed a 10% advantage in favour of the 10m WWTP with flotation.
Estimation of oxygen transfer rate in sequencing batch reactor
Authors: Liao Y. C. , Lee D. J.
Published: May 2018

Transient model of oxygen transfer rate in a sequencing batch reactor is derived and solved numerically. The dissolved oxygen response under several conditions is analyzed. Effects of operational parameters and liquid bath height are studied. When with short, intermittent aeration periods, the transient effects on oxygen transfer rate may be substantial and should be taken into considerations. An example considering bioreaction is also given.
Transport of chlorinated hydrocarbons between sewage and sewer atmosphere
Authors: Haas Bettina S. , Herrmann Reimer
Published: May 2018

Sewage containing volatile contaminants is a potential VOC-source in cities. Thus we tried to evaluate volatilization out of the sewerage system by measurements of contaminants in sewer gas and sewage. Our results from a medium sized town with little industry showed that sewer gas is mainly contaminated with alkanes, small aromatic compounds and chlorinated hydrocarbons. For three chlorinated hydrocarbons (chloroform, trichloroethene, tetrachloroethene) we determined mass transfer coefficients out of sewage and used these data to estimate mass fluxes from sewage and emissions out of the sewerage system for two sewer stretches. Considerable emission of chlorinated hydrocarbons from sewage, i.e. fluxes of some 10 to 100 g per m2·d, occurred only when the contaminant input via sewage was between some g and mg per litre for a single compound. For concentrations that were about 3 orders of magnitude less, emissions were negligible.
Integrated approach to the point-non point-pollution abatement in urban drainage
Authors: Krejci Vladimir
Published: May 2018

An area in Switzerland of 260 km2 with 230 000 inhabitants was analysed for the feasibility of combined sewage overflow (CSO) tanks to reduce the pollution in receiving waters during rain events. The case study demonstrates the consideration of the point and of the non point pollution with respect to choice and application of water pollution control measures in urban drainage. For example, measures which reduce pollutant sources (e.g. substitution of phosphorus in detergents) or reduce surface runoff (e.g. dispersed retention or infiltration of rainfall runoff) are more efficient than a strategy of uniform and area wide application of CSO tanks. The new Swiss guideline for Integrated Urban Drainage Master Planning (IUDMP) introduces a radical changes in the scope and in the procedures of planning process. This guideline defines the urban drainage system as one single system, consisting of urban area, soil and ground water system, drainage network, waste water treatment plant and receiving waters. The consideration of comprehensive urban drainage system allows the choice of site-specific and problem-related measures.
The watershed protection approach
Authors: Brady Donald J.
Published: May 2018

The Water Protection Approach (WPA) by USEPA is outlined. The historical development of the approach is of an old date, starting since 1980. Definition of the approach and experience to date is summarized. It is not a new programm, but a new way of thinking about how environmental programs have to be managed.
Legislative tools in the Czech watershed management policy
Authors: Holas J. , Konvicková M.
Published: May 2018

Potential environmental impacts as a result of large-scale farming system in the Czech Republic have created a great deal of concern in recent years. This concern has led to several studies to identify the role of new regulations, directives and other legislative issues in the field of water pollution control. The set of legislative tools related to watershed management policy to promote better agricultural practices is shortly reviewed. The paper emphasises the running water law system amendment with respect to European community water quality regulations.
Sources and transport of phosphorus in the Vltava river basin (Czech Republic)
Authors: Hejzlar Josef , Vyhnálek Vojtech , Kopácek Jirí , Duras Jirí
Published: May 2018

Export and sources of P in the Vltava basin (subbasin of upper Elbe: total area – 28,093 km2; population density – 115 km−2; forests – 35%, farmland – 51%) were evaluated during 1972–1993. Annual export rates of total P from the basin to the river Elbe ranged between 38 and 68 kg km−2 a−1. Reservoirs with hydraulic retention times longer than 15 days were efficient traps for phosphorus retaining 20 to 30% of total P loading into the watercourses. Point sources (municipal wastewaters) were most important throughout the period and their share varied from approximately 60% in wet years to more than 90% in dry years. Export from diffuse sources (dominated by output from farmland) was highly dependent on discharge and fluctuaded between 5 and 40 kg km−2 a−1 in dry and wet years, respectively. Only about 2% of the P input into the basin from the fertilisation of farmland and from the atmospheric deposition was exported to the watercourses.
Vulnerable areas of phosphorus leaching - detection by gis-analysis and measurements of phosphorus sorption capacity
Authors: Behrendt Horst , Lademann Lena , Pagenkopf Wolf-Gunther , Pöthig Rosemarie
Published: May 2018

A model is presented to detect vulnerable areas of phosphorus leaching combing GIS-modeling and measurements on phosphorus sorption capacity of different soil types. The GIS-model uses spatial information on the topology, land use, soil types, water tables and climatic water balance. The phosphorus surplus of the agricultural topsoil is estimated based on the average of fertilizer use and the uptake by crops over a long period of time and, additionally, the application rates of manure around cowshed and pigsties.

The model is applied to the catchment area of Lake Schwielochsee, a hypertrophic shallow lake situated about 100 km south-east of German capital, Berlin.

The phosphorus content and the phosphorus sorption capacity were measured at several sides with differing soil types. Parameters of the GIS-model are deduced from the results of these measurements.
Reducing diffuse pollution through implementation of agricultural best management practices: a case study
Authors: Cook M. G. , Hunt P. G. , Stone K. C. , Canterberry J. H.
Published: May 2018

A system of agricultural best management practices (BMPs) was implemented on a 2,100 ha watershed in Duplin County, North Carolina, USA, for the purpose of improving water quality. The BMPs included: Nutrient, pest, and animal waste management; and soil conservation practices. Both surface and ground water were continually analyzed to assess the water quality impacts. Nutrient management plans have been developed for over 80% of the cropland. Pest management plans have been developed for over 60% of the cropland. Over one-half of all plans have been implemented. Poultry mortality composting and improved swine waste management have decreased the potential adverse effects of animal operations. A constructed wetland shows promise as a pre-treatment of swine waste prior to land application.

Stream monitoring shows decreasing amounts of nitrate- and ammonium-nitrogen in the surface waters of the watershed. Ground water monitoring shows relatively high concentrations of nitrate in areas of intensive swine and poultry operations. Ground water monitoring of pesticides reveals low levels of alachlor, atrazine, and metolachlor even though large amounts of these chemicals are used on crops. The successful implementation of agricultural BMPs appears to be having a positive effect on water quality. Both stream and ground water monitoring will be continued for several years to assess more definitively the changes in water quality.
Atmospheric transport and deposition of trace elements to lake erie from Urban areas
Authors: Keeler Gerald J. , Pirrone Nicola
Published: May 2018

A hybrid receptor-deposition (HRD) modeling approach was used to determine the spatial and temporal variation in the ambient concentration and dry deposition flux of trace elements on fine (< 2.5 mm) and coarse (> 2.5 mm) particulate matter over Lake Erie. Upper-air observations from the National Weather Service (NWS) and ambient concentrations measured at two sampling sites downwind of major emission sources in the Lake Erie basin were input to the model. An evaluation of the deposition flux of size-segregated trace elements to the lake during the over-water transport was performed. The average total (fine + coarse) deposition flux was 9.6 ng/m2-h for V, 70 ng/m2-h for Mn, 3.2 ng/m2-h for As, 4.2 ng/m2-h for Se, 10 ng/m2-h for Cd, and 43.3 ng/m2-h for Pb.
The use of constructed wetlands for the treatment of run-off and drainage waters: the UK and Ukraine experience
Authors: Magmedov Vyacheslav G. , Zakharchenko Michael A. , Yakovleva Ludmila I. , Ince Margaret E.
Published: May 2018

It is now clear that constructed wetlands for waste water treatment and nature conservation are wide spread in the USA and becoming more common in most European countries, Australia, in some regions of Asia and Africa. In this paper we analysed more than ten years experience of constructed wetlands implementation in the United Kingdom and Ukraine. A design, construction features and equations for constructed wetlands area estimation used in both countries are compared. The efficiency of BOD, SS and nitrogen removal by subsurface flow type and combined type flow constructed wetlands also discussed. On the basis of experience obtained on constructed wetlands implementation in both countries for storm water, run-off and drainage treatment, we suggest that they may be the best option to block diffuse sources of pollution.
Enhancing the removal of pollutants by an on-stream pond
Authors: Van Buren M. A. , Watt W. E. , Marsalek J.
Published: May 2018

A methodology is presented for assessing the pollution control performance of an on-stream pond located in Kingston, Ontario, Canada, and enhancing the removal of pollutants by remediation techniques., Descriptions are provided of the instrumentation used to measure continuously rainfall and water levels, and the sampling program to collect stormwater samples., The assessment is based on examining contaminant removals for both baseflow and event conditions and applying in-pond remedial measures to improve pond performance., Results on removal rates are provided for selected dissolved constituents (total dissolved solids, sulphate and chloride), nutrients, suspended solids, metals and organic contaminants., In summary, dissolved constituents exhibit zero removal for baseflow periods and positive removal for events; nutrients and suspended solids exhibit negative removal for baseflow periods and positive removal for events; and metals and organics exhibit positive removal for both baseflow periods and events. Remediation techniques are discussed and preliminary results of one technique — internal pond baffles — indicate that extended hydraulic residence times and prevention of flow short-circuiting result in increased particulate settling and associated contaminant removal.
Use of microbiological and biological methods for monitoring the influence of diffuse pollution on reservoir's water quality
Authors: Mlejnková Hana , Žáková Zdenka
Published: May 2018

The research results of water supply reservoirs and their tributaries in the Morava River basin showed the important role of the biological and microbiological investigations by monitoring the influence of diffuse pollution on the reservoir's water quality. Our report brings the critical evaluation of the possibility to use some microbiological and biological methods by monitoring of diffuse pollution, it also includes some practical results received from monitoring the streams and reservoirs within the Morava River basin (in the frame of research projects of the T. G. Masaryk Water Research Institute, branch office Brno).
Molecular weight distribution of soluble microbial products in biological systems
Authors: Boero V. J. , Bowers A. R. , Eckenfelder W. W.
Published: May 2018

The molecular weight, MW, distribution of soluble microbial products, SMP, was examined. Phenol, an inhibitory substrate, and glucose, a non-inhibitory substrate, were degraded using acclimated cultures of bacteria. Three distinct regions were found to exist, Region I: Original substrate present, Region II: Biodegradable SMP present, and Region III: Endogenous respiration. Phenol degradation resulted in more SMP than glucose, about 25 percent versus 3 percent as residual SMP at the end of Region I, and 3 percent versus 1 percent at the end of Region II, respectively. In Region III, the production of SMP due to endogenous decay, SMPE, was proportional to the rate of cell degradation. The rate coefficient for SMPE production for cells grown on phenol was higher than for glucose, 0.005 mg SMPE per mg cell carbon per day for phenol versus 0.002 mg per mg per day for glucose. Although differences existed in the magnitude of SMP produced, the MW distributions for phenol and glucose were similar in each region. While in Region I most of the SMP consisted of the lowest MW (<1 K daltons) compounds, 90 percent for phenol and 75 percent for glucose, at the end of Region II only 41 percent of the SMP for phenol and 56 percent for glucose were in the <1 K fraction. Finally, for endogenous decay products, 48 and 50 percent of the SMPE were in the highest MW fraction >100 K.
Studies of microbial acclimation to hard chemicals on the basis of respiratory quinone profiles and kinetic analyses
Authors: Hu Hong-Ying , Nozawa Mamie , Fujie Koichi , Makabe Tsuyoshi , Urano Kohei
Published: May 2018

The population dynamics of microbes in the biological wastewater treatment processes such as a submerged biofilter was investigated to obtain basic information to determine the optimal operating conditions. The effects of coexistence of biodegradable substances such as glucose and peptone on the acclimation of microbes in the biofilm to hard chemicals such as acrylonitrile (AN), which is poorly biodegradable and a volatile substance, was investigated on the basis of the respiratory quinone profile. Kinetic study of the removal of AN in the course of acclimation of microbes was investigated using a laboratory-scale submerged biofilter as well. It was ascertained that the acclimation of the microbes to AN was accelerated by coexistence of biodegradable substances, and the microbial phase after acclimation differed from those with the coexistence of glucose and peptone. The quinone profiles in the acclimation showed that Brevibacterium sp. and Pseudomonas aeruginosa, of which the predominant quinone of the respiratory chain is menaquinone-8(H2) and ubiquinone-9, respectively, multiplied selectively in the acclimation course without and with the coexistence of glucose and peptone, respectively. It was also made clear that there were few kinds and number of protozoa and metazoa in the biofilter treating the wastewater containing AN.
Grease biodegradation: is bioaugmentation more effective than natural populations for start-up?
Authors: Mendoza-Espinosa Leopoldo , Stephenson Tom
Published: May 2018

Investigations were undertaken in order to compare the grease degradation rates for a natural population of acclimatised activated sludge micro-organisms with a commercial bioaugmentation product (bioadditive) under optimum conditions in laboratory-scale batch reactors. Lard was chosen as the source of grease because it contains the fatty acids more commonly found in urban wastewaters. During acclimatisation, the bioadditive reactor achieved a slightly better chemical oxygen demand (COD) removal efficiency than the activated sludge reactor. Therefore, under optimum conditions, activated sludge was able to degrade grease at nearly the same rate as a bioadditive solution. Moreover, the bioadditive and the activated sludge reactors had very similar kinetics of COD removal under different grease concentrations. It was concluded that the use of natural activated sludge micro-organisms was sufficient to acclimatise biological processes to removing grease.
Modeling kinetics of chloroform cometabolism in methanogenic and sulfate-reducing environments
Authors: Gupta Munish , Suidan Makram T. , Sayles Gregory D.
Published: May 2018

The kinetics of chloroform cometabolism in methanogenic and sulfate-reducing environments were modeled. Chloroform inhibits acetate utilization in methanogenic environments and therefore the rate of chloroform cometabolism was modeled using two terms: cometabolism due to primary substrate utilization and cometabolism due to microbial cell decay (no primary substrate utilization). The modified Haldane equation was used to model chloroform cometabolism due to primary substrate utilization and the Monod equation was used for the cometabolism due to microbial cell decay. A commercial software, SigmaPlot (Jandel Scientific Software) was used to determine the optimum parameters for the model. The model agreed very well with the experimental results. The model parameters confirmed that the sulfate-reducing culture has a very high potential for chloroform cometabolism compared to the methanogenic cultures. Also, the methanogenic culture grown on acetate is very sensitive to chloroform compared to the methanogenic culture grown on methanol.
Startup of thermophilic (55°C) UASB reactors using different mesophilic seed sludges
Authors: Fang Herbert H. P. , Lau Ivan W. C.
Published: May 2018

Performances during startup of three 2.8-litre UASB (upflow anaerobic sludge blanket) reactors operated under thermophilic condition were investigated. All reactors were seeded with mesophilic sludges: one with flocculent digester sludge (Reactor-F), another with UASB granules (Reactor-G), and the third with disintegrated granules (Reactor-D). The reactors were operated in parallel at 55°C and 24 hours of retention time, using sucrose and milk as substrate at COD (chemical oxygen demand) loadings up to 10 g-COD/l·day. Immediately after temperature was step-increased from 37°C to 55°C, all reactors encountered sludge washout and deterioration of COD removal efficiency; however, the impact of temperature increase was more severe on Reactor-F. Sludge granulation took place in all reactors; first granules became noticeable after 45 days in Reactor-D, and after 90 days in Reactor-F. Reactor-G and Reactor-D were capable of removing 95% of soluble COD after 75 days, while Reactor-F after 110 days. Throughout this study, there was little difference in performance between Reactors G and D. The thermophilic granule were estimated to have a yield of 0.099 g-VSS/g-COD, and a methanogenic activity of 0.71-1.55 g-methane-COD/g-VSS·day, comparable to that of mesophilic granules.
Reductive dechlorination pathways of chloro organics under anaerobic conditions
Authors: Susarla Sridhar , Masunaga Shigeki , Yonezawa Yoshitaka
Published: May 2018

The transformation pathways of chloroanilines (CAs), chlorobenzenes (CBs) and chlorophenols (CPs) were examined in anaerobic sediment collected from the Tsurumi river, Japan. The sediment was pre-exposed to various organic chemicals from the surrounding industries and appears to be sulfidogenic. Experiments were carried out for each compound in the sediment slurry, which was spiked at a desired concentration. The transformation of the parent substrate and the appearance of its metabolites were monitored for a year. All the compounds transformed without any lag period. For CBs, the preferential Cl removal was in the order: two Cl atoms on adjacent carbon atoms > one Cl atom on adjacent carbon > no adjacent Cl atom on the carbon. In case of CPs, ortho dechlorination was the preferred pathway, while for CAs, sequential removal of ortho and para positions was observed.
Biodegradation of herbicide chlornitrofen (CNP) and mutagenicity of its degradation products
Authors: Tanaka Y. , Iwasaki H. , Kitamori S.
Published: May 2018

Chlornitrofen has been widely used as a diphenyl-ether-derived herbicide for the rice paddy fields. Thus, the present study was undertaken to see whether CNP and its degradation products are mutagenic, and how CNP can be degraded in the natural environment. The following results were obtained.

(1) CNP was weakly mutagenic in a new test strain YG 1029 but not mutagenic in the other strains tested here, even in both strains TA 100 and TA 98 that are conventionally used as the most sensitive strains in the Ames test. CNP was a direct-acting mutagen that does not require a metabolic activation system (S9 mix).

(2) Amino-CNP, a degradation product of CNP, was potentially mutagenic in the strains YG 1029 or YG 1024 and was a moderate mutagen in the other test strains employed here. Amino-CNP required S9 mix for the mutagenesis, suggesting that a metabolite of amino-CNP is an active mutagen. Acetylamino-CNP, another degradation product of CNP, was also mutagenic with almost the same strains, although the mutagenic potency was somewhat lower than that of amino-CNP. No mutagenicity was detected for the other degradation products, hydroxy-CNP, dichlorophenol, trichlorophenol, and p-chlorophenol.

(3) The diphenyl-ether-derived herbicides nitrofen and chlormethoxynil, which are structurally related to CNP, and their amino derivatives were tested for their mutagenicity in a similar way. Chlormethoxynil was not mutagenic in all strains tested, but nitrofen was highly mutagenic in strain YG 1026 and weakly in YG 1029 when tested in the presence of S9 mix. In contrast, amino-nitrofen and amino-chlormethoxynil were mutagens with quite similar properties to those of amino-CNP, respectively.

(4) The biological degradation of CNP was tested using river water. It was observed that CNP degraded rapidly and was converted to amino-CNP with a high efficiency in river water. An increase in the mutagenicity of the testing solution could be seen depending upon the decay of CNP, formation of amino-CNP, and elevation of temperature. It seems that most of the mutagenicity observed may be due to the mutagenicity of amino-CNP formed from CNP by microorganisms in the river water.
Effect of temperature on biodegradability of surfactants in aquatic microcosm system
Authors: Takamatsu Y. , Nishimura O. , Inamori Y. , Sudo R. , Matsumura M.
Published: May 2018

Microcosm systems consisting of producer, decomposer and predator were employed to assess the effect of surfactants (LAS and soap) on an aquatic ecosystem at various temperatures. At all test temperatures (10, 20, 25 and 30°C), stable ecosystems were formed with regard to the biomass and species composition in flasks. In the stationary phase, temperature dependency of ATP was observed and the biodegradation rate of the surfactants in microcosm system at low temperature were slower than that at high temperature. Cyclidium glaucoma, Philodina sp. and Aeolosoma hemprichi as predator were more influenced by surfactants at low temperature. No observed effect concentration (NOEC) of LAS was less than 0.5mg·1−1 at 10°C, less than 1.5mg·1−1 at 20, 25°C and less than 2.5mg·1−1 at 30°C. NOEC of soap was less than 10mg·1−1 at 10°C, less than 30mg·1−1 at 20, 25°C. It was found that biodegradability of surfactants differed with temperature, which changed the effects of surfactants on microorganisms.
Estimating toxicity of mixtures of organic chemicals to activated sludge using surrogate test cultures
Authors: Nirmalakhandan N. , Peace J. , Egemen E. , Mohsin M. , Sun B. , Hall E.
Published: May 2018

The feasibility of estimating toxicity of synthetic organic chemicals to activated sludge using surrogate test cultures was evaluated. The commercial culture, Polytox, evaluated in this study yielded consistently reproducible results. Experimentally determined IC50 values for 50 chemicals for Polytox cultures correlated well with activated sludge with r2 = 0.922. Similar agreement was found between IC50 values reported in the literature and those measured for Polytox (r2 = 0.762). Additional comparisons were made between activated sludge and Polytox based on joint toxicity of mixtures of organic chemicals. Excellent correlations were found between the concentrations of the constituents in 8- and 10-component mixtures that jointly caused 50% inhibition of the two microorganisms.
H2S papers as presumptive tests for Salmonella contamination in tropical drinking water
Authors: Gawthorne Tanya , Gibbs Robyn A. , Mathew Kuruvilla , Ho Goen E.
Published: May 2018

Coliform bacteria may not be adequate as sole indicators of recent faecal contamination in tropical waters. Salmonella spp. in particular have been found in tropical waters in the absence of traditional indicator bacteria. Remote areas without access to a laboratory have no opportunity for salmonellae analysis as portable tests are currently not available. H2S papers indicate the presence of hydrogen sulphide producing bacteria, a characteristic shared by the majority of Salmonella spp.. The potential of H2S papers to act as a presumptive test for salmonellae in the absence of coliform bacteria was assessed.

Salmonella spp. grew in the H2S medium, with an optimum incubation temperature of 37°C and a recommended length of incubation for a negative result of 48 hours. The presence of high numbers of the type of noncoliform bacteria commonly found in drinking water did not affect the performance of the H2S strips. H2S papers are recommended for use in conjunction with a coliform test as a presumptive test for the presence of Salmonella spp. in drinking water.
Clean-up of contaminated sites: experiences in the netherlands
Authors: Rulkens W. H. , Honders A.
Published: May 2018

The number of more or less strongly contaminated sites in the Netherlands amounts to about 100,000. For more than ten years soil treatment techniques have been developed and used to clean-up those contaminated sites. The major clean-up techniques for excavated soil are extraction/wet classification, thermal treatment and biological treatment by landfarming. With extraction/wet classification experience is available with the treatment of sandy soils with a clay or humus percentage of less than 20%. The type of pollutants which have been removed with extraction/classification varies strongly: PAH, hydrocarbons, mineral oil, cyanides, Cd, Zn, Cr, Cu, Pb and Ni. With thermal treatment, experience is available with all types of soil, contaminated with cyanides, PAH, mineral oil, hydrocarbons, gasoline and HCH. With landfarming, experience is limited to the treatment of sandy soils polluted with easily biodegradable components such as gasoline hydrocarbons, low molecular PAH and mineral oil. Up to now more than 4,000,000 tonnes of soil have been treated with these methods. The major in situ clean-up methods are liquid extraction, soil vapour extraction and biorestoration. However, in comparison with the clean-up of excavated soils the practical experience with these in situ methods is still limited. Research and development is still going on and is especially focused on the improvement of the clean-up techniques for excavated soil, and the improvement and further development of in situ treatment techniques, especially in situ biorestoration.
The effect of clay amendment on speciation of heavy metals in sewage sludge
Authors: Qiao L. , Ho Goen
Published: May 2018

When sewage sludge is used as a soil conditioner, heavy metal contamination can limit its application rates. The potential hazard of heavy metals is, however, dependent on the physico-chemical forms of the metals in the sludge and soil. Bauxite refining residue (red mud) has been used to reduce the mobility and availability of heavy metals in municipal solid waste compost. In the present research a sequential step extraction was employed to investigate metal speciation (into exchangeable, bound to carbonate, to Mn & Fe oxides, to organic matter and in residue phase) and the effect of red mud on metal speciation in sewage sludge for Cd, Cr, Cu, Ni, Pb and Zn. The effect of red mud addition on metal distribution in sewage sludge compost was significant. Red mud addition can effectively reduce the metal mobility and the potential hazard of releasing metals from sludge due to the further breakdown of organic matter. Drying of sludge makes heavy metals more available. Red mud addition will be desirable in such a case. Plant available metals (determined by DTPA extraction) are, however, not as effectively reduced except for Pb and Zn.
Optimization in thickness of a liner composed of claymax® and organo-clay
Authors: Lo Irene Man-Chi
Published: May 2018

Present design philosophy reflects the uncertainty about the long-term effectiveness of liner systems by incorporating redundancy in the barrier layers through the concurrent use of both geosynthetic and clay minerals. A possible reason may be the lack of an engineering based design procedure for liners and a lack of a suitable optimization model which can be used to predict liner performance. In this study, Claymax® and Organo-Clay are chosen to be the liner materials because of their low hydraulic conductivity and high sorption capacity, respectively. The simulation model “Pollute 3.3” is combined with the Generalized Reduced Gradient Methods “GRG2” code to form an optimization model. The objective of this optimization model is to provide a tool for engineers to design a liner of reasonable thickness that protects the environment and maximizes disposal space. It was found that the total liner thickness is dependent on the sorption capacities of chemicals, equivalent hydraulic conductivities, and the geometry of a landfill.
Evaluation of the WHO nematode egg guidelines for restricted and unrestricted irrigation
Authors: Blumenthal Ursula J. , Mara D. Duncan , Ayres Rachel M. , Cifuentes Enrique , Peasey Anne , Stott Rebecca , Lee Donald L. , Ruiz-Palacios Guillermo
Published: May 2018

Epidemiological studies were conducted in Mexico to assess the health risks associated with restricted crop irrigation using raw and treated wastewaters. Experimental studies were done in northeast Brazil and Leeds, in which Ascaris lumbricoides contamination of lettuces spray-irrigated with raw wastewater and waste stabilization pond effluents containing different helminthological qualities was determined (Brazil); and Ascaridia galli infection was monitored in immunosuppressed chickens fed lettuces spray-irrigated with water containing different A. galli egg numbers (Leeds). The results indicate that the WHO guideline quality of ≤ 1 egg per litre protects crop consumers, but not necessarily fieldworkers and their families especially children. This is particularly the case when wastewater treatment systems are not stable, when recontamination of the partially treated wastewater with small quantities of raw wastewater may occur, and when wild vegetables are harvested and consumed. In such cases a stricter guideline quality of ≤ 0.5 egg per litre may be required.
Retardation factors and breakthrough times of organic micropollutants in groundwater recharged with effluents
Authors: Rav-Acha Chaim , Duchovni Irene , Kanarek Adam , Izakson Neli , Rebhun Menachem
Published: May 2018

In the Dan Region Reclamation Center (DRRC) in Israel, secondary effluents, after a mechanical - biological treatment and polishing ponds, undergo a Soil-Aquifer Treatment (SAT), in the course of which these are recharged into an isolated aquifer, and the repumped water is used for various agricultural purposes. In the present study a simple model has been developed in order to predict retardation factors and breakthrough times of various micropollutants in the SAT system. The model is based on the linear free energy relationship between adsorbtivity of organic compounds and their hydrophobicity as expressed by their octanol - water partition coefficients. A very good correlation was found between the predicted values calculated by the model, and experimental laboratory results of adsorption isotherms and breakthrough curves.
Development of methodology for the optimal operation of soil aquifer treatment systems
Authors: Tang Zongwu , Li Guihua , Mays Larry W. , Fox Peter
Published: May 2018

Soil aquifer treatment (SAT) systems are used for reclamation of sewage effluent by groundwater recharge. Increasing demand on water supplies has stimulated the production or planning of many SAT systems that will use reclaimed wastewater for groundwater recharge. These systems are comprised of a series of infiltration basins. The design and operation of soil aquifer treatment systems presently relies primarily upon judgment and experience. This research effort is developing a methodology for determining the optimal operation of SAT systems that is based upon mathematically describing the problem as a discrete-time optimal control problem. The resulting mathematical problem is a large-scale nonlinear programming problem. Solution of the problem is being accomplished by interfacing a nonlinear programming optimizer, which is solved by a differential dynamic programming algorithm, with a simulator that describes the infiltration process, unsaturated flow, effects of surface clogging and biological clogging, biological removal of nitrogen and organics. Major efforts are devoted to numerical performance of the optimization model solution, and development of the simulator. Initial results of interfacing the optimizer with the simulator without water quality concern show high convergence rate. The operation pattern determined by this method is reasonable. This new methodology will be a tool for engineers to evaluate choices regarding the potential of the design and operation of SAT systems.
Operational efficiency of a pilot plant for wastewater reuse
Authors: Croce Fulvio , Hendricks David , Pollara Joe , Poulsom Susan , Oliveri Rosalaura , Torregrossa Maria Valeria , Valentino Laura , Candura Ranieri
Published: May 2018

Reuse of wastewaters for non-potable uses needs a higher than normal reliability in treatment plant operation and management, in order to ensure higher safety margins for public health and environmental protection. After a two-years research project on a pilot plant designed for agricoltural reuse, all control parameters used for the plant operation have been examined, in order to obtain useful observations on efficiency of each of the treatment units, for best overall performance. It was concluded that this type of package plant was able to produce a high quality effluent under various conditions, providing a good confidence on the reliability of the system.
Environmental assessment for wastewater reclamation and reuse projects
Authors: Kontos Nick , Asano Takashi
Published: May 2018

The purpose of an environmental review and assessment is to incorporate environmental considerations into the planning process. Prior to the selection of a specific project alternative, a thorough and unbiased analysis of the environmental impacts of every reasonable project alternative should be made. It is intended that environmental concerns be considered on an equal basis with engineering feasibility, economics, and social considerations in wastewater reclamation and reuse. This paper discusses the “procedural” and “substantive” provisions of environmental law in the United States; National Environmental Policy Act (NEPA), and more specifically the law in California; California Environmental Quality Act (CEQA). The procedural aspects require the preparation of an environmental document such as an environmental impact statement (EIS) or an environmental impact report (EIR) and the substantive provisions require mitigation of harmful environmental impacts. Suggested outlines of the content of an EIS and an EIR are provided. Specific impacts associated with wastewater reclamation projects such as groundwater impacts and growth inducing impacts are discussed. This paper is intended to be a useful tool for the planning of any wastewater reclamation and reuse project. Two examples are given for this purpose.
A novel biofilm-membrane reactor for ammonia oxidation at low concentrations
Authors: Watanabe Yoshimasa , Kimura Katsuki , Okabe Satoshi , Ozawa Genzou , Ohkuma Naoki
Published: May 2018

For the oxidation of low concentrations of NH4+-N, conventional biofilm reactors such as a rotating biological contactor encounter difficulty due to mass transport limitation of NH4+-N. Therefore, the authors have developed a novel biofilm-membrane reactor, in which biomass is fixed on the surface of rotating membrane disks to enhance NH4+-N transport into the biofilm. Three long-term bench-scale experiments were carried out and sufficient nitrification efficiency was obtained even at low levels of NH4+-N. The experimental results were evaluated in comparison with model simulation.
Modelling of the growth of a methanotrophic biofilm
Authors: Arcangeli Jean-Pierre , Arvin Erik
Published: May 2018

A model describing the growth of a methanotrophic biofilm is presented. This model involves simultaneous growth of methanotrophs, heterotrophs and nitrifiers. Heterotrophic biomass grows on soluble polymers which arise from the hydrolysis of dead biomass entrapped in the biofilm. Nitrifiers develop because of the presence of ammonia in the mineral medium. A comparison of this model with experimental data showed that the biofilm growth, methane removal, oxygen consumption, product formation and biofilm detachment could be fitted well. Parameter estimation yielded a maximum growth rate for methanotrophs, μm, of 1.17 ± 0.2 d−1, at 20°C, a decay rate, bm, of 0.34 ± 0.06 d−1, a half-saturation constant, KS(CH4), of 0.08 ± 0.05 mg CH4/l, and a yield coefficient, YCH4, of 0.21 ± 0.03 g X COD/g CH4 COD. In addition, a sensitivity analysis has been performed for this model. It indicated that the most influential factors were those related to the biofilm (i.e. density; solid volume fraction; thickness). This suggests that in order to improve the model, further research is needed in the field of biofilm structure and composition.