bluuebunny/crossref_metadata_2025 huggingface dataset:
Measuring success in water pollution control
Authors: Holmes Paul R.
Published: May 2018

Ambient water quality is much used to show progress in water pollution control. The state of the environment is not easy to measure reliably and may be subject to very many factors other than the impact of polluting discharges and those who seek to control them. Even measured trends in water quality do not prove that the pollution control activity is being managed to the best standards of efficiency and effectiveness. So managers may have great difficulty in measuring their success or in correctly attributing change in the environment to their action. On the other hand, owners of pollution control systems, both public and private, make little allowance for scientific scruples in their demands for objective measures of effectiveness. The paper examines the theory behind these contradictions and uses the recent development of performance indicators for environmental management in Hong Kong to consider how theory and practice differ. It concludes that effectiveness is relative, but pollution control managers can help themselves if they integrate into their organizations a constant alertness to fundamental goals.
Current and planned disposal of sewage sludge and other waste products from the ruhrverband wastewater treatment
Authors: Bode Harro , Imhoff Klaus R.
Published: May 2018

From the year 2005 onwards German waste disposal regulations prevent the disposal of residual wastes from sewage treatment plants in landfills if the waste contains more than 5% volatile solids by dry mass. As a result of this requirement the Ruhrverband, one of Germany's largest sewage treatment plant operators, needs to change its disposal methods to a certain extent. This paper describes the present ways to dispose of sludge as well as of screenings and grit. After that it outlines the concept for future disposal. Besides the legal framework the technical solutions for the different disposal problems are described and their costs are given.
Application and experience with expert systems for the operation of waste water treatment plants
Authors: Ladiges Gösta , Mennerich Artur
Published: May 2018

Expert systems have been shown to be a good method for combining the different information that is required and is useful for the operation of waste water treatment plants. This paper describes the contents of and experience with the expert system EXTRA, that has been developed for optimizing and problem solving purposes. The system has been applied at two plants since 1992 and 1993. Within a current project a third application will be installed until summer 1995.
Biological phosphorus removal from wastewater in a single reactor combining anaerobic and aerobic conditions
Authors: Choi Yong Su , Shin Eung Bai , Lee Young Dae
Published: May 2018

In this investigation, phosphorus removal experiment was conducted in a single reactor combining anaerobic and aerobic conditions. Attempts have been made to delineate phosphorus and organic removal mechanisms and to evaluate the removal efficiencies with different internal recyle ratios, N/P ratios and varying SRT conditions. The removal efficiencies of TOC, BOD and COD were observed to be higher than 95%, 90% and 90% in all runs, respectively. It is further estimated that the optimal operational conditions for phosphorus removal are observed when the aerobic internal recycle rate is 100% with the inlet height 0.2H. The percent removal efficiencies were 92% for T-P and 90% for PO4-P. While, large differences in the removal of phosphorus with N/P ratios were observed; at influent TKN/T-P of 2.5, 3.6 and 5.1 removal efficiencies for T-P were 89%, 68% and 56%, respectively. Those removal efficiencies decreased as the N/P ratios increase in wastewater. In case of SRT, high removal efficiencies are observed with the solids retention time of 10 days rather than with SRT's of 5 or 20 days. These results indicate this new process, KNCR (Kist Nutrient Removal Compact Reactor), to be an excellent means of reducing phosphorus emissions into the environment.
Application of experimental research methodology to the study of nitrification in mixed culture
Authors: Mauret M. , Paul E. , Puech-Costes E. , Maurette M. T. , Baptiste P.
Published: May 2018

Nitrification is an aerobic process formed by two consecutive reactions: nitritation and nitratation. Using an experimental research methodology, we have studied the specific effects and the possible interactions between initial ammonia concentration, pH and temperature on these two reactions as well as on the experimental conditions leading to a nitrite build-up.

In the experimental field studied (35 < [N-NH4+]O mg.l−1 < 90, 15 < T°C < 25 and 7 < pH < 8.5), the statistic interpretation of the results shows that only temperature and pH have a significant positive effect on ammonia removal. Moreover, the effect of these two parameters is linear. As for nitrite accumulation, the temperature effect is negligible and a strong interaction between [N-NH4]O and pH is revealed. When the values of these two variables are high, nitratation is inhibited and 50% of the nitrogen introduced at the beginning accumulates temporarily in the form of nitrites.

The results clearly show that a high NH3 concentration inhibits Nitrobacter, starting from between 6.6 and 8.9 mg N-NH3.l−1.

This research enables a better understanding of the nitrite build-up phenomena which can be thus minimized or maximized in the case of new process of nitrogen treatment.
Treatment of high-strength nitrate wastewater by biological methods - operational characteristics study
Authors: Chen Shing-Der , Chen Chiu-Yang , Shen Yuan-Chung , Chiu Chun-Mao , Cheng Hsiang-Ju
Published: May 2018

Recently, the research in biological denitrification applied to low nitrate concentration municipal wastewater and polluted groundwater has gained considerable attention. There is, however, much less research on high-strength nitrate industrial wastewater treatment by biological denitrification. The present investigation hence aims towards studying biological treatment of high nitrate concentration wastewater for removal of nitrogen components and understanding its operational characteristics. Three different types of bioreactors, viz.: an activated sludge reactor (ASR), a biologically mediated activated carbon fluidized bed reactor (BAFBR), and an upflow immobilized cell reactor (UICR) were used. Results revealed that the start-up period of UICR was the shortest, followed by BAFBR, while it was longest for ASR. Thus higher volumetric load appears to lead to a shorter start-up period. From long periods of operation, it was observed that the volumetric load of BAFBR was the highest (30 kg N/m3-d), followed by UICR (8.9 kg N/m3-d) and the lowest (1.0 kg N/m3-d) was ASR. The influence of power outage or system shutdown was found to be the most significant for BAFBR, the second most affected was UICR, and ASR was the least affected. The ability to acclimate to shock loading was observed to be best for UICR, the next was BAFBR, while the worst was ASR.
Nitrate removal from water using cyclically operated fixed-film bio-denitrification reactors
Authors: Dahab M. F. , Kalagiri J.
Published: May 2018

In this paper, a study of cyclically-operated fixed-film bio-denitrification to remove nitrates from drinking water is reported. The purpose of the study was to investigate the ability of these two-stage systems to remove nitrate and residual organics from treated water as compared to single-stage units. In the cyclically-operated system, the second stage (i.e. follow) reactor is operated in series with the first stage (i.e. lead) reactor. After a given period of operation, the flow regime is reversed so that the follow reactor becomes the lead one and vice versa. The active solids remaining in the follow reactor (previously the lead one) are capable of removing residual soluble organics and nitrates to levels below the concentrations provided by single-stage units. Cyclically operated fixed-film bio-denitrification reactors were found to reduce long term effluent residual organics concentrations without adverse effects on the nitrate concentrations. The system also was found to be more effective in reducing nitrates, nitrites and soluble organic concentrations in the effluent than a single-stage system operated at the same hydraulic retention times and organic loading rates.
High rate and compact two-stage post-denitrification process with single-sludge pre-denitrification
Authors: Mikawa Kazuhiro , Emori Hiroyoshi , Takeshima Tadashi , Ishiyama Eiichi , Tanaka Kazuhiro
Published: May 2018

For the sewage treatment plants near rivers and closed water bodies in urbanized areas there is a growing demand for introduction of advanced treatment processes for nitrogen and phosphorus removal for water quality conservation and environmental protection. In order to achieve the total nitrogen content of below 10 mg/L in effluent, a compact single sludge pre-denitrification process by dosing immobilized pellets in the nitrification tank (PEGASUS process) has been already developed (Tanaka et al. 1992). Furthermore, a two-stage PEGASUS process and a PEGASUS process with post-denitrification were developed and investigated for nitrogen removal. Both processes achieved the total nitrogen of less than 5mg/L.
Qualitative mode of action of sewer tanks with surplus flow
Authors: Pecher K. H. , Haußmann R.
Published: May 2018

The sewer tank is a specific type of overflow tank. While sewer tanks with a surplus flow at the beginning of the sewer are regarded as uncritical, in sewer tanks with a surplus flow at the end of the sewer, sedimentation may be remobilised and transported into the receiving waters. For this reason, in Germany, additional capacity over and above the minimum requirements is demanded for these sewers.

In order to ensure the qualitative mode of action of sewer tanks with a surplus flow at the end of the sewer, pilot-scale investigations into a model sewer, with artificial combined water, as well as large-scale investigations under real life conditions, were carried out.

The findings of these investigations illustrated that a sedimentation of solids takes place in the majority of flow circumstances, including times of overflow. Thus, even at times of high stormwater flow, the outflow to the receiving waters contains only a low level of pollution. As well as storing the stormwater, the sewer tank with a surplus flow at the end of the sewer has the additional environmentally friendly effect of improving the quality of the outflow and reducing its pollution content.
Adaptive control of external carbon flow rate in an activated sludge process
Authors: Lindberg Carl-Fredrik , Carlsson Bengt
Published: May 2018

In this study an adaptive carbon flow rate controller is applied to a pre-denitrifying pilot-scale plant. The goal of the control strategy is to maintain a low nitrate concentration in the anoxic zone by controlling the external flow rate of the carbon source. Results from practical experiments show that the control strategy works well and the nitrate concentration could be kept close to a desired set-point (reference value). The used nitrate sensor needed, however, frequent maintenance. During the experiment the carbon flow rate was automatically varied to keep the nitrate concentration at a constant low level. We conclude that a low effluent nitrate concentration without an excessive carbon flow rate is hard to achieve without an automatic control strategy.
Combined control of sewer and treatment plant during rainstorm
Authors: Nielsen Marinus K. , Carstensen Jacob , Harremoës Poul
Published: May 2018

The use of flow predictions and on-line nutrient sensors in BNR plants has given the basis for introduction of radical operational changes. Because of the detailed monitoring, the control actions are allowed to go closer to critical process limits while balancing between hydraulic and biological capacities.

One of the new modes of operation, settling in the aeration tanks as an active control, is documented below. This new operation, Aeration Tank Settling (ATS) has been tested at full scale and shows a great potential for storm water control. With ATS control the hydraulic capacity is increased 25–75% on existing plants without reducing the organic capacity in periods ranging from 2 hours to 2 weeks.

ATS control can be initiated directly by raising the inlet flow to the treatment plant, but even better by 1/2 - 1 hour prediction of the inlet flow. These predictions of flow are achieved from statistical grey-box handling of data from on-line rain gauges and measured inlet flow pattern during normal and stormwater conditions.

Hourly predictions of concentrations in the inlet to the plant and selected points in the sewer system during dry weather and storm situations will improve the combined system control efficiency radically.
Operational problems of wastewater filtration plants - their analysis and possible solutions
Authors: Dohmann Max , Feyen Herbert A , Sanz Juan Pablo , Zenzes Norbert
Published: May 2018

During the last 15 years, mechanical-biological wastewater treatment plants in Germany have been increasingly supplemented by filtration plants. Their technology, which is based on the one used for drinking water processing, had to be adapted to the differing circumstances. Companies specialised in filtration, as well as engineering offices are planning these plants. Workers at wastewater treatment plants had to learn how to operate the filters. Not all the necessary adaptations went smoothly. A number of operational problems have occurred during the last few years. Some problems have been analyzed by the Department of Environmental Engineering of the Aachen Technical University (ISA), leading to suggestions for avoiding these mistakes in the future.
Membrane aerators and stirring systems for the operation in large and small wastewater treatment plants
Authors: Höfken Marcus W. A. , Huber Peter , Schäfer Marcus , Steiner Ralf
Published: May 2018

Stirring and aeration processes are the major operations needed for effective wastewater treatment. Especially in activated sludge processes and the variants of this process stirring and aeration systems need to be chosen carefully since both operations are crucial for the purification power and the energy demand of wwtp's. The aim of the present work is to define the demands on stirring and aeration systems for activated sludge treatment plants, to give an overview about suitable systems currently available on the market including latest developments and to give advice how to choose the optimum system.

A brief review of the literature and the market of stirring and aeration systems leads to a simple classification of the existing numerous systems. In order to choose the optimum system, first one has to decide, about the demands in each process step. In anaerobic and anoxic reactors the use of hyperboloid stirring systems or combined hyperboloid stirring and aeration systems which distribute small air bubbles throughout the entire reactor in the aeration mode (for intermittent aeration) and gently circulate bacteria flocks in the stirring mode is recommended. For aerobic processes like BOD-removal and nitrification highly efficient membrane aerating systems using silicone membranes are recommended.
Mechanical pre-thickening of excess sludge: influence on the process technology of anaerobic sludge treatment and operating experiences
Authors: Buer Thomas R. , Roos Hermann-Josef , Pecher Klaus
Published: May 2018

A volume reduction of the sludges with relatively low solid matter contents encountered during water treatment is a requirement for the economical treatment and disposal of sludges. Therefore, during expansion of anaerobic sludge stabilisation plants, new methods are increasingly being applied that provide for mechanical pre-thickening of the excess sludge. At present, there is no safe database describing the influence of the higher solid matter concentration and the resulting increased raw sludge viscosity on the sludge treatment. This paper introduces various results of a targeted survey regarding this subject characterising differences in the methodology and operation during sewage sludge treatment between plants with and without separate mechanical excess sludge thickening. It turns out that plants that have a mechanical excess sludge pre-thickening unit are more frequently subjected to mechanical and apparatus-related operation problems, although in practice the increase of the solid matter concentration in the raw sludge is only 20–25% compared to conventionally operated plants.

The maximum achievable solid matter content in the thickened excess sludge - and therefore that in the raw sludge - is especially dependent on the choice of the mechanical pre-thickening unit and the application of a flocculant. At the same time, plants with mechanical pre-thickening of excess sludges achieve a higher gas yield and degree of stabilisation. On the whole the results of the survey lead to the conclusion that mechanical pre-thickening of the excess sludges is better applied for the training of sludge treatment plants, which show sludge solid matter contents of less than 4% DSM (dried solid matter) under normal operating conditions.
Beneficial use of biosolids: progress in controlling metals
Authors: Isaac Russell A. , Boothroyd Yuhsia
Published: May 2018

Beneficial use of wastewater and its by-products is receiving increasing attention. The objective is to maximize the resource value and minimize the need to consider disposal only. While not always possible, more opportunities for such uses are being pursued. One aspect of this effort is the beneficial use of biosolids or, as it long has been known, sludge. Even the change in terminology reflects the effort to consider these materials as potential resources. While the new term may reflect more an effort to make such materials acceptable to the public from a psychological basis, efforts to assure the material is acceptable based on health risks by minimizing hazards from organisms and chemicals are prerequisite. Among the contaminants of concern are several elements. In the mid 1970s (designated 1975) and during the last several years (designated 1993), samples of wastewater solids were collected from 22 publicly owned wastewater treatment facilities (POTWs), all with pretreatment programs, in Massachusetts. These samples were analyzed for seven metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn). While there are several potentially confounding factors such as differences in sampling and analytical methods, the fact that the mean concentrations of all seven of the metals monitored decreased during the interval 1975–1993 when the two sets of data (126 and 54 samples respectively) were collected suggests that pretreatment and pollution prevention efforts have contributed to improving the quality of biosolids.
Odour measurement - factors affecting olfactometry panel performance
Authors: Bliss P. J. , Schulz T. J. , Senger T. , Kaye R. B.
Published: May 2018

To identify factors affecting olfactometry panel performance in the measurement of environmental odours, a data bank of odour threshold measurements including 923 individual panel tests on environmental odours and 145 tests on standards were analysed statistically. There is an evident decrease in olfactory sensitivity to environmental odours with age. The group threshold tends to be one step lower for a 25 year increase in average age of panel members for Type I odours (piggery, feedlot, landfill and mushroom composting) and for 36 years increase for Type II odours (sewage and industrial coke works). The threshold for N-butanol tends to be 1 step lower for an increase of 15 years in age. People who are over 40 years old exhibited a greater variation than younger people. Although there was a minor gender difference in the sensitivity to butanol standard, it was not statistically significant (mean natural logarithm butanol threshold was 3.65 for males and 3.84 for females). Similar minor differences were exhibited in Confidence Index (CI), 1.72 for females (std. dev. 0.73) and 1.81 for males (std. dev. 0.77). Using “guess and correct” as criterion to determine individual thresholds in the forced choice olfactometry, the mean natural logarithm of ppb butanol is 1.365 lower than that for “certain and correct”. The standard deviation for “guess” and “certain” criteria were 1.093 and 0.911 respectively. The “certainty” criterion gave a better repeatability than the “guess” criterion.
Main topics and recent experiences for environmental monitoring and modelling diffuse pollution
Authors: Preti Federico
Published: May 2018

Monitoring and modelling are two complementary instruments necessary for the analysis of pollution phenomena, such as groundwater contamination and lakes eutrophication, often generated by diffuse (nonpoint) sources (NPS). A review of scientific literature has been conducted to obtain the information necessary to develop a correct methodology relative to environmental field monitoring and modelling agricultural nonpoint pollution. A questionnaire has been handed out to several researchers who are involved in this research field in order to learn of other pertinent activities being undertaken and to facilitate the exchange of information. Testing and verification of a methodology for the analysis of contamination caused by the use of agrochemicals, based on field monitoring studies and the application of a distributed nonpoint pollution model, have been conducted in Italy. Based on the research developed and practical experience, some of the main guidelines for conducting studies of pollution processes caused by agriculture as well as a summary of theoretical and practical aspects encountered in the design of field and basin scale model validation studies and in the use of published experimental results to test models can be proposed.
Ecotechnological methods for managing non-point source pollution in watersheds, lakes and reservoirs
Authors: Straškraba Milan
Published: May 2018

Ecotechnological methods are considered those using technological means for environmental management in a way to minimize the harm to the global environment. Three reasons to use ecotechnological methods are given: they are cheap, minimize the use of raw materials and protect the global environment. In the article the most cost-efficient and environmentally friendly ecotechnologies for non-point source pollution management are given. These are divided into two categories: those done in the watershed and those used within the lake or reservoir. In the first category wetland use, restoration and construction is shown to efficiently reduce different kinds of pollution. The construction of small pre-impoundments is effective for trapping phosphorus as the main cause of eutrophication. In the category of in-lake approaches several are mentioned: biomanipulation or food web manipulation leading to decreased eutrophication, many approaches of mixing and aeration based on recent limnological knowledge, selective withdrawal as a manipulation of outflow and drinking water intake depths in reservoirs, the diversion of polluted inflow waters and sucking of hypolimnion waters. The limitations of the methods are given. Mathematical models helpful in optimizing the use of the corresponding methods are shown.
Regional materials accounting of nitrogen in upper Austria
Authors: Zessner M. , Kaas T. , Brunner P. H. , Fleckseder H.
Published: May 2018

A nitrogen balance for the region of Upper Austria is presented containing a short introduction to the method and materials used and the overall results with emphasis on the N balance for the atmosphere, agriculture and surface waters. It is shown that it was possible to obtain only with existing data an overall balance for nitrogen which takes all important nitrogen fluxes into consideration. Important results are: The biggest input of nitrogen (as NHX-N or NOX-N) into the atmosphere comes from agriculture, but also traffic and industrial processes play an important role. The N-losses from agriculture to the environment depend to a high extent on the rate of animal protein production. The N-input to surface waters from nonpoint source discharges is noticeably bigger than from point source discharges.
The influence of lime application to the acid soil on bioavailability of phosphorus in runoff
Authors: Sova Vít
Published: May 2018

The influence of lime application to the acid soil on the mobility of phosphorus (P) in runoff was investigated by simulated rainfall in laboratory conditions. The neutralization of the acid soil by appropriate amount of lime significantly increased the portion of loosely bound phosphates in runoff sediment This phenomenon influenced bioavailability of P in runoff which increased after the lime application.
Upgrading performance of an activated sludge process through addition of talqueous powder
Authors: Cantet J. , Paul E. , Clauss F.
Published: May 2018

This study is intended to induce better performance of existing activated sludge wastewater plants without modifying the physical structure of the plant.

The process consists in injecting a specific mineral powder into the aeration stage with two precise purposes: firstly to improve floc structure and thus facilitate solid/liquid separation in the clarifier, and secondly to reduce nitrogenous pollution.

By means of two experimental models the indisputable and rapid effect of talc/chlorite blend on the solid/liquid separation was established (with a sludge volume index improvement by a factor of 2 to 3 within a few days) compared with a control unit.

The increase in nitrification capacity of the system is also clearly shown with nitrification yields being increased by 30%. These results lead us to believe that it is possible to use this process of enhanced nitrification for running a plant reliably without dysfunctioning.

Problems linked to hydraulic or biological excess loading can be solved this way. Moreover, the addition of talqueous powder improves sludge dewaterability.
The significance of microbial Fe(III) reduction in the activated sludge process
Authors: Nielsen Per Halkjær
Published: May 2018

The significance of microbial Fe(III) reduction in activated sludge was evaluated with regard to: its importance as electron acceptor; as a producer of acetate during anaerobic conditions; for phosphate release; and for its role in the floc structure. Potential Fe(III) reduction rates were measured in 6 wastewater treatment plants with and without biological P-removal and found to be in the range of 0.9-5.4 mgFe/gVSS h. Assuming an incomplete oxidation of organic matter leading to acetate formation, Fe(III) reduction was a major acetate source, providing substrate to phosphorus-accumulating organisms (PAO) during anaerobic conditions. The observed high potential Fe(III) reduction rate might also be responsible for a significant chemical phosphate release due to reduction of Fe(III) to Fe(II) in clarifies, sludge storage tanks and anaerobic tanks in plants with biological P-removal. Investigation of the concentrations of Fe(II) in a full-scale treatment plant in anaerobic tanks, oxic/anoxic tanks and return sludge indicated that both reduction and reoxidation took place in the treatment plant. Reoxidation of Fe(II) to Fe(III) in activated sludge was shown to take place with oxygen and probably also during anoxic conditions with nitrate and nitrite as electron acceptors. The results indicate that Fe may be more involved in important processes in activated sludge than hitherto assumed, so a better understanding of Fe interactions in activated sludge is desirable.
Towards understanding the taxonomy of some of the filamentous bacteria causing bulking and foaming in activated sludge plants
Authors: Blackall Linda L. , Seviour Elizabeth M. , Bradford Debbie , Stratton Helen M. , Cunningham Mitchell A. , Hugenholtz Philip , Seviour Robert J.
Published: May 2018

Several filamentous bacteria obtained in pure culture from activated sludge plants were characterised using their 16S rDNA sequences to determine their phylogenetic relationship to other bacteria. “Microthrix parvicella” was shown to be an unusual actinomycete, while the Gram negative bacteria Type 0092, Type 0411 and Type 1863 all belong to the Flexibacter-Cytophaga-Bacteroides phylum, and Type 0803 is a member of the beta subclass of the Proteobacteria. The practical value of obtaining this information is discussed.
Lysis of filamentous bacteria by surfactants
Authors: Kitatsuji Katsura , Miyata Hiroshi , Fukase Tetsuro
Published: May 2018

A microbial substance that lyses filamentous bacteria was obtained. The substance also exhibited some properties of a bio-surfactant. Lysing of filamentous bacteria with synthetic surfactants was also examined. Several synthetic surfactants were found to be capable of lysing filamentous bacteria. Nonionic synthetic surfactants with an HLB of 11-15 were found to lyse type 1701 and type 021N in an activated sludge sampled from a sewage treatment plant. Use of the synthetic surfactant to lyse filamentous bacteria was also demonstrated in a continuous-feed aeration tank, and settleability of sludge was improved. The surfactants did not adversely effect floc-forming microorganisms as evidenced by the high rate of TOC removal. The results indicate that synthetic surfactants can be used to prevent filamentous bulking in the activated sludge process.
Microbiology of activated sludge treating wastewater containing Ni(II) and Cr(VI)
Authors: Dilek Filiz B. , Gökçay Celal F.
Published: May 2018

The species of microorganisms dominating a laboratory-scale once-through activated sludge unit treating simulated wastewater with different influent strengths (650 and 1300 mgl−1 COD) and containing 5 to 10 mgl−1 Ni(II) and 1 to 50 mgl−1 Cr(VI) were identified by standard biochemical tests. Within this framework, combinations of metals and influent COD concentrations were tried. Organisms, namely Proteus rettgeri, Acinetobacter sp., Flavobacterium lutescens, Bacillus cereus var. albolactis, Klebsiella sp., Arthrobacter simplex, and Pseudomonas mendocina, were identified at different stages of the experiments.
Treatment of gypsum waste in a two stage anaerobic reactor
Authors: Deswaef S. , Salmon T. , Hiligsmann S. , Taillieu X. , Milande N. , Thonart Ph. , Crine M.
Published: May 2018

The reduction of high concentrations of gypsum (up to 110 kg/m3) is investigated in a two stage immobilised cell bioreactor. The first stage is mainly colonised by a consortium of acidogenic bacteria and sulphate reducing bacteria oxidising volatile fatty acids with more than 2 carbons (mainly, butyrate and propionate). The gypsum consumption rate is rather high (11 kg/m3.day). Most of acetate remains unconverted in this first stage. It is partially converted in the second stage (residence time : 12 days) which is predominantly colonised by acetate oxidising bacteria. The gypsum consumption rate is much lower than in the first stage: 3 kg/m3.day. With both stages, it is possible to reach an almost complete conversion of gypsum with an overall capacity of 6.1 kg gypsum/m3.day. We propose also a very simple model to describe the different transformation rates. It allows us to clearly identify the activity levels of the different types of sulphate reducing bacteria in both stages.
Longitudinal dispersion and biomass hold-up of anaerobic fluidized bed reactors
Authors: Turan M. , Öztürk I.
Published: May 2018

Longitudinal dispersion in fluidized bed reactors was studied using pulse-response techniques for both clean and anaerobic-biofilm coated media. A large number of experimental data on the longitudinal dispersion and biofilm growth in the anaerobic fluidized bed reactors (AFBRs) were investigated. Some correlations applicable to fluidized beds were obtained for both the hydraulic retention time and the biomass concentration versus the ratio Pe/Re. The biomass concentration tends to zero for a critical retention time in AFBRs. The biological growth in the bed causes an increase of Pe number.
Ecotoxicological studies using modified ames bioassay
Authors: Filipic M. , Toman M. J.
Published: May 2018

Health and environmental risk assessment of river and wastewaters based on single chemicals is limited by the number of chemicals that can be identified and to those chemicals for which toxicity and mutagenicity data exist. In this study Salmonella/microsome mutagenicity assay was evaluated as a potentially useful biomonitoring system for river water and wastewater. Standard assay was modified to allow testing of up to 2.5 ml of nonconcentrated water sample and by introducing 90 minutes of preincubation. Mutagenic activity of nonconcentrated samples was compared to the mutagenic activity of XAD-2 extracts of the same samples. Eighteen river water samples, two wastewater samples and one sample of water leaking from municipal waste dump were tested. Mutagenicity was detected in three nonconcentrated river water samples, both nonconcentrated wastewater samples and in the sample of the water leaking from the municipal waste dump. The mutagenic profiles of nonconcentrated samples were different from the mutagenic profiles of the XAD-2 extracts. The modified method was sensitive enough to detect mutagens present in more polluted river water (class IV), in wastewaters and in water leaking from the municipal dump. For the assessment of the impact of the mutagenic river and wastewaters on the environment, calculations from the results of nonconcentrated samples should be used as it seems that calculations from the results of the extracts are leading to the underestimation of mutagenic potency. Mutagenic profiles of the extracts are a useful guide for further chemical and biological analysis to trace the sources of the mutagens and to introduce measures to reduce them.
Activities of ligninolytic enzymes of the white rot fungus, phanerochaete chrysosporium and its recalcitrant substance degradability
Authors: Wu Feng , Ozaki Hiroaki , Terashima Yutaka , Imada Toshihiro , Ohkouchi Yumiko
Published: May 2018

The factors influencing the activities of extracellular ligninolytic enzymes synthesized by white rot fungus,Phanerochaete chrysosporium , were investigated by batch culture experiments. The LiP activity was maximal under the nitrogen-sufficient condition, compared with the activities under both conditions of the nitrogen-limited and nitrogen-excess. The manganese-dependent peroxidase (MnP) activity was highest under nitrogen-limited condition. Veratryl alcohol was found to be the most important substrate enhancing lignin peroxidase (LiP) activity in carbon-limited medium. The decolorization of azo dye (Reactive Red 22) by P. chrysosporium in the presence of both LiP and MnP under carbon-limited condition was greater than that in the presence of MnP under nitrogen-limited condition. Two chlorinated substances (2,6-DCP and MCPA) were degraded under conditions of nitrogen-limitation and notrogen-sufficiency. The azo dyes were also decolorized by the crude extracellular ligninolytic enzymes from P. chrysosporium.
The potential role of the estuarine amphipod Gammarus duebeni in sub-lethal ecotoxicology testing
Authors: Lawrence Andrew , Poulter Carl
Published: May 2018

The aim of this study was to assess the suitability of Gammarus duebeni as an indicator of estuarine pollution. This involved the development of sub-lethal pollution bioassays monitoring respiration rate, swimming efficiency and precopula pairing; assessment of the sensitivity of the assays to copper pollution and comparison of the suitability of the assays. Significant impairment of respiration rate, as measured by changes in pleopod beat, was determined at a copper concentration of 600 μg 1−1. Significant impairment to swimming ability was determined after exposure to copper pollution at a concentration of 600 μg 1−1 and precopula pairing was significantly reduced at a concentration of 600 μg 1−1. Of the assays, swimming efficiency and pleopod beat frequency appear to offer the most potential for further development. The lower limit of sensitivity of the bioassays developed in this study is yet to be determined. However, the levels of copper shown to induce an effect can be experienced in the natural environment. The study has shown thatGammarus duebeni can be used in sub-lethal pollution assays, at relatively high Cu concentrations, and indicates that it is potentially a useful species with which to assess estuarine water and sediment pollution.
Development of a water temperature-ecological model to stimulate global warming effects on lake ecosystem
Authors: Hosomi Masaaki , Saigusa Tetsu , Yabunaka Kenichi , Okubo Takuya , Murakami Akihiko
Published: May 2018

This paper describes a newly developed combined water temperature-ecological (WT-ECO) model which is employed to simulate the effects of global warming on lake and reservoir ecosystems. The WT model includes (i) variations in the eddy diffusion coefficient based on the degree of thermal stratification and the velocity of wind, and (ii) a sub-model for simulating the freezing and thawing processes of surface water, water temperatures, and the mixing rates between two adjacent layers of water. The ECO model then uses these results to calculate the resultant effect on a lake's ecological dynamics, e.g., composition of phytoplankton species, their respective concentrations, and nutrient concentrations. When the model was benchmarked against Lake Yunoko, a dimictic lake, fairly good agreement was obtained over a 4-yr period; thereby indicating it is suitably calibrated. In addition, to assess the effects of global warming on a lake ecosystem, changes in Lake Yunoko's water temperature/quality were simulated in response to an increase in air temperature of 2 - 4°C. Results indicate that such an increase will (i) increase thermal stratification in summer, which increases the nutrient concentrations in bottom water due to nutrient release from bottom sediment, (ii) increase the concentration of phytoplankton at the beginning of the autumn circulation period, and (iii) change the composition of phytoplankton species.
The use of radiation-induced advanced oxidation for water reclamation
Authors: Gehringer Peter , Eschweiler Helmut
Published: May 2018

An advanced oxidation process (AOP) for water reclamation, particularly groundwater remediation is described. It is based on a combination of ozone and electron beam irradiation. Main pathways of the hydroxy free radical generation in such a combination are reviewed and compared with those of other AOPs. New data is presented regarding the effect of the direct introduction of gaseous ozone into the irradiation chamber on pollutant decomposition, and the impact of the pH value on OH free radical production. Special attention is paid to an assessment of the combined ozone/electron beam process in comparison to other AOPs.
The dewaterability, heavy metal release and reuse characteristics of golden horn surface sediment
Authors: Karpuzcu M. , Buktel D. , Aydin Z. S.
Published: May 2018

In this study the dewaterability, heavy metal release and reuse characteristics and reuse of Golden Horn surface sediment were investigated under remediation considerations. Determination of factors like specific resistance to filtration and moisture type of sediment is a prerequisite for rational selection of the most cost-effective volume reduction process. Twenty five percent and seventy five percent of the water content were of free and immobilized, and of bound nature, respectively, with a high resistance value revealing poor dewaterability characteristics. The leachate did not contain toxic heavy metals, even at pH 3. The sediment had strong adsorbability for Cu and Pb, and high buffering capacity. The reuse of the dried sediment as a clay mixture in brick manufacturing seemed possible up to 40 percent.
Improved fenton method to remove recalcitrant organics in landfill leachate
Authors: Gau S.-H. , Chang F.-S.
Published: May 2018

Sanitary landfill leachate is usually treated with biological process followed by FeCl3 coagulation, but the effluent still contains high concentration of COD. The Fenton method can substitute for chemical coagulation to improve the removal of recalcitrant organics. Instead of using the traditional Fenton method and FeCl3 coagulation, we investigated a two-stage Fenton process and Fenton method with PAC, in which MW chromatography was used to evaluate the fraction of organic removal in detail. We have found that the Fenton method could remove low molecular weight fractions better than FeCl3; evidently, the two-stage Fenton method is better than a one-stage for a higher requirement of COD removal, and carbon adsorption can remove oxidation-resistant organics efficiently. The proper combination of two-stage Fenton with carbon adsorption can satisfy the COD effluent standards.
Wastewater reuse for irrigation in France
Authors: Bontoux Jean , Courtois Gérand
Published: May 2018

In France the study of available pluviometric data shows that in some regions, where the need of water would not be satisfied, large hydraulic installations are existing (channels, dams, networks) that are limiting the consequences of this deficit. Therefore, France is not a country where direct reuse of wastewater for irrigation is a primary preoccupation of responsible authorities of water resource management. However, it is noteworthy that spreading wastewater on areas which may be suited for agricultural use, is in France a traditional practice within the bounds of sanitation and management. More recently there is also noted the enthusiasm for golf courses, big consumers of water in tourist areas particularly demanding in water resources during summer, as the development of big scale quasi-industrial cultures, for example those of maize very demanding in water quantity. The ministry of health, conscious of the public health problems, which possibly arise by wastewater reuse for irrigation, has published in 1991 guidelines, concerning this special field, developed by the Superior Council of Public Hygiene of France (C.S.H.P.F.). A major topic in these guidelines is to subordinate, case per case, every reuse to an administrative authority, previous appropriated to a strict control of the applied procedures. The objective of this present communication is to present, four years after their publication, a first assessment of this guideline application. In particular the following points result: a) spreading out wastewater stays in priority an alternative solution, as their reject in surface water is impossible; the objective in agriculture is in this case secondary. b) justified reuse by agricultural use is exceptional and never involve in practice cultures of products to be eaten uncooked. c) sprinkling golf courses have been object of relatively many cases; several quality control programs have been installed by the Ministry of Health and definite authorisations of use have been accorded.
Wastewater reuse in Tunisia: assessing a national policy
Authors: Bahri Akissa , Brissaud Francois
Published: May 2018

An ambitious national wastewater reuse policy was launched at the beginning of the eighties in Tunisia. The area currently equipped for irrigation with reclaimed wastewater, mainly secondary effluents, is 6,500 hectares. It is planned to expand this area to more than 20,000 ha in the next years. The rate of reclaimed water reuse, 15% of the available water, is still low compared to the potential. Irrigation is practiced only six months per year; reclaimed water is not stored during the non irrigation season. Shifting from rainfed to wastewater irrigated crops is a progressive process. Irrigated schemes surveys point out that wastewater reuse development is hampered by crop restrictions more than by supply drawbacks. As a result, disinfecting secondary effluents in order to remove restrictions on water reuse is contemplated. Storing reclaimed water, in reservoirs or aquifers, would lead to more reliable supplies, water quality improvement and an increase in the rate of reuse. Developing the irrigation of golf courses, green belts and hotel gardens should be a convenient policy in tourist areas.
Potential for reuse of treated effluent in Istanbul
Authors: Tanik Aysegul , Sarikaya Hasan Zuhuri , Eroglu Veysel , Orhon Derin , Oztürk Izzet
Published: May 2018

This paper evaluates potential sources of effluent reuse and feasible reuse applications in Istanbul Metropolitan Area, within the framework of all technical issues that must be considered in the planning and implementation of water reuse systems. Some potential sources of effluent for reuse have been eliminated based on location, on treatment plant size, or both. An assessment made of future possible reuse applications in the vicinity of wastewater treatment plants now under construction or planned has identified the following possibilities: Tuzla; industrial, urban and groundwater recharge; Küçükçekmece; urban, industrial, recreational, augmentation; Büyükçekmece; urban, industrial, augmentation; Ömerli - Elmalý; augmentation. The applications proposed for Istanbul have been based on technical, financial, economic, environmental and health considerations. The evaluation based on the current and anticipated programme of construction and commissioning of treatment facilities confirms that large scale reuse applications in Istanbul will not be a major consideration for the planning horizon.
The performance of batch stabilization reservoirs for wastewater treatment, storage and reuse in Israel
Authors: Juanico Marcelo
Published: May 2018

Stabilization reservoirs receive partially treated wastewater effluents for storage and controlled release. They are used in Israel for two purposes: a) to upgrade the quality of the effluents during the long residence time within the reservoirs and, b) to store the effluents during the rainy winter in order to perform agricultural irrigation during the dry summer. The improvement obtained in the quality of the effluents (i.e., the treatment capacity of the reservoirs) depends on the operational regime of the reservoirs as reactors: continuous flow, in series, batch, etc. The performance of the reservoirs as batch reactors for wastewater treatment is herein analyzed based on outdoor experiments carried out in real scale reservoirs with different hydraulic and organic loadings. The results of the experiments are compared with forecasts obtained through statistical and kinetic models. Stabilization reservoirs working in batch mode, when properly designed and operated, are able to remove COD, BOD, TSS and detergents by up to one order of magnitude, and Faecal coliforms by up to five orders of magnitude (before chlorination). A significant removal of heavy metals, bacteriophages and other pollutants is also obtained. The quality of the effluents released from the reservoirs, added to the capability for controlled release, permits both wide crop rotation and easy management of irrigation.