bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of solids management on nutrient ratios for in-line wastewater prefermenters
Authors: Rössle W. H. , Pretorius W. A.
Published: May 2018

The full-scale evaluation of in-line prefermentation effects on wastewater nutrient ratios was performed under three different sludge operating conditions, with regards to sludge elutriation rates (0.7, 2.2 and 3.7 kg dry sludge/m3 raw sewage) and the corresponding sludge ages (17.3, 2.5 and 7.5 days). At all three operating conditions the TKN/COD ratio increased (64, 46 and 20% respectively), with an average ratio of 0.057 mg N/mg COD in the raw sewage increasing to 0.082 mg N/mg COD in the settled sewage. These ratio increases can limit the use and performance of certain biological nutrient removal process configurations. This study has further highlighted the importance to counterbalance fermentation, thickening and solids removal requirements in a single tank in-line prefermenter. The minimum suspended solids removal (33%) was achieved at the lowest settled sludge solids content (4.3%), against a corresponding maximum volatile fatty acid generation rate (5.7 mg VFA/l/h). The total solids and volatile fatty acid concentration profiles down the prefermenter tank depth were determined at a high sludge blanket level condition. It was demonstrated that the accumulated constituent mass inventory increase was about constant throughout the water and sludge layers respectively under such operational conditions.
Modern management instruments - control of a water resources management association by means of an agreement on targets (balanced scorecard)
Authors: von Seidlitz A. E. , Londong J.
Published: May 2018

Since the matter of water supply and sewage disposal is safeguarded in Germany, public concern would no longer appear to be directed at questions of disposal reliability, but almost exclusively to economic efficiency. The requirements with respect to sewage disposal are dominated not only by growing environmental regulations and technical challenges, but also to a major extent by a discussion on the costs arising. In order to ensure a viable and at the same time economic water supply and sewage disposal despite this, it is necessary to have a holistic corporate control system. As a counterpart to the river basin management approach adopted at the Wupperverband there is, on the business management side, the agreement on targets (balanced scorecard) as a management and controlling approach. This incorporates purely financial variables as well as non-financial variables in the economic valuation of corporate success. The starting point is the formulation of strategic goals, while including customer-oriented, in-company and forward-looking perspectives, taking into account at the same time the interactions between them. A major perspective of such balanced scorecards is customer satisfaction. By means of an intensive dialogue with members, licensing and supervisory authorities of the Wupperverband within the framework of a holistic corporate control, it has been possible not only to improve corporate success, but also, and more importantly, to achieve an appreciable increase in confidence.
Process using DO and ORP signals for biological nitrification and denitrification : validation of a food-processing industry wastewater treatment plant on boosting with pure oxygen
Authors: Mauret M. , Ferrand F. , Boisdon V. , Spérandio M. , Paul E.
Published: May 2018

The simultaneous removal of carbonaceous and nitrogenous pollution by the activated sludge process is becoming common in industrial and municipal wastewater treatment plants. An oxygenation monitoring process has been developed, which is based on the dynamic analysis of ORP and DO signals and allows the detection of specific characteristic points at the end of the biological nitrification and denitrification.

The aim of this study is to validate this process in a food-processing industry WWTP (slaughterhouse) having large variations of carbonaceous and nitrogenous loads. In order to treat during the peak period, pure oxygen is used. The first part of the study provides a precise diagnosis of the WWTP operation by the analysis of the ORP and DO signals. It is particularly easy to estimate the level of nitrogen treatment actually achieved and the oxygen requirements, and to detect the over- or under-oxygenated phases.

Thanks to the monitoring process, the aerobic period of each cycle is reduced to the optimal duration, providing a reduction of 30% on the energy consumption compared to a traditional schedule. We have demonstrated that the use of pure oxygen associated with the existing air system is particularly relevant for the peak period. The revamping of an existing plant to simultaneously treat the carbon and the ammonia in the same basin is now technically feasible.
Use of real time control modelling on the urban sewage system of Nancy
Authors: Zug M. , Faure D. , De Belly B. , Phan L.
Published: May 2018

Since 1991, European Legislation on the urban treatment of wastewater requires local authorities to take into account the treatment of polluted water transported by the sewerage system and this during dry and wet weather conditions. In the seventies, the urban Community of Grand Nancy constructed storage tanks in its sewerage system in order to prevent flooding and wish today to use them to reduce and control the pollution discharges into the receiving water. This action is a part of a European LIFE project 1996-2000. The main aim of this project was to assess the effectiveness of reducing pollution of one particular retention basin, the 12,000 m3 Gentilly tank. This one has two operating modes: protection against floods during heavy rain and reduction of pollutant overflows during lighter rain. To assess its effect on the pollutant discharge, the HYDROWORKS DM(tm) software and its Real Time Control Module have been used, calibrated and validated. As this study is still in progress, this paper describes the studied site and the modelling results under different weather conditions and shows that the mathematical model can be used to simulate the operation of the catchment area and its associated sewerage system realistically.
Interest of a multibiomarker approach in the assessment of freshwater ecosystem quality: laboratory and field studies
Authors: Vidal M. L. , Bassères A. , Narbonne J. F.
Published: May 2018

The aims of this study were to validate several biochemical parameters as biomarkers of pollution in the freshwater bivalve Corbicula fluminea and to underline the interest of a multibiomarker approach in environmental biomonitoring. The study was divided into a laboratory exposure to 4 doses of trichloroethylene, toluene, cadmium chloride or a coal tar fraction for 5 days and a field exposure for one week in 5 sites surrounding an industrial effluent outlet. Whatever the product was, parameters that exhibited significant responses were mainly parameters related to oxidative stress and components of phase I metabolism. As a result of discriminant analysis, doses were clearly discriminated from the control and from each other. Likewise, products were discriminated from each other, based on results of the whole parameter responses obtained for the first dose. Concerning the field experiment, all biochemical parameters assayed exhibited significant responses for sites located downstream of the effluent outlet, compared to the upstream reference site. Through a discriminant analysis, sites could be distinguished from each other in terms of pollution intensity. In order to characterise pollution at a qualitative level, further laboratory and field studies are needed to obtain typical profiles for the main pollutants present in freshwater ecosystems.
Annual nutrients export modelling by analysis of landuse and topographic information: case of a small Mediterranean catchment
Authors: Payraudeau S. , Tournoud M. G. , Cernesson F. , Picot B.
Published: May 2018

The preservation of water bodies from eutrophication implies accurate estimation of phosphorus and nitrogen loads and the control of nutrient production on a catchment scale. In this paper, a simple tool for the modelling of annual nutrient loads is presented. It is implemented in ARC/INFO GIS using Arc Macro Language (AML). The use of a GIS is justified as the spatial characteristics of the catchment area (land use, industrial wastewater location) dictate water quality. The annual nutrient loads are worked out on the catchment scale, using existing GIS routines together with specific routines developed in AML for hydrological and water quality modelling purposes. The catchment area is divided into hydrological subcatchments with relatively homogeneous spatial characteristics. Each subcatchment is linked to a specific nutrient export potential. These nutrient loads, calculated on a subcatchment-by-subcatchment basis, are conveyed to the outlet of the catchment and allow annual nutrient load estimation. A comparison with a water monitoring study is conducted to verify the adequation of modelling results for phosphorus and nitrogen loads.
Water quality management in the coastal city in the period of considerable water consumption decrease
Authors: Bogdanowicz R. , Drwal J. , Maksymiuk Z. , Osinski A.
Published: May 2018

Gdansk water supply system belongs among the oldest in Continental Europe. In 1992 one of the first joint-venture water companies was established in the city. Under a contract concluded between the firm and the municipality, the company was obliged to secure quick and considerable improvement of drinking water quality. At the same time a considerable water consumption decrease was observed. The drop entails new environmental, technical and economic problems. The biggest threat to the supplies of safe and good quality water is the phenomenon of secondary pollution of water resulting from the overdimensioning of the water supply network. Positive aspects of water consumption decrease are related to the opportunity of more rational and sustainable water resources management. The solutions adopted in Gdansk can serve as a starting point for working out the best model for water quality management in the coastal cities.
Performance of a recirculating wetland filter designed to remove particulate phosphorus for restoration of Lake Apopka (Florida, USA)
Authors: Coveney M.F. , Lowe E.F. , Battoe L.E.
Published: May 2018

Operation of a 14-km2 wetland filter for removal of total phosphorus (TP) from lake water is part of the restoration program for hypereutrophic Lake Apopka, Florida. This system differs from most treatment wetlands because 1) water is recirculated back to the lake, and 2) the goal is removal of particulate phosphorus (P), the dominant form of P in Lake Apopka. The operational plan for the wetland is maximization of the rate rather than the efficiency of P removal. The St. Johns River Water Management District operated a 2-km2 pilot-scale wetland to examine the capacity of a wetland system to remove suspended solids and particulate nutrients from Lake Apopka. TP in the inflow from Lake Apopka ranged from about 0.12 to 0.23 mg l-1, and hydraulic loading rate (HLR) varied from 6.5 to 42 m yr-1. The performance of the pilot-scale wetland supported earlier predictions. Mass removal efficiencies for TP varied between about 30% and 67%. A first-order, area-based model indicated a rate constant for TP removal of 55 m yr-1. We compared actual removal of P with model predictions and used modeled performance to examine .optimal operational conditions. Correspondence between observed and modeled outflow TP was not good with constant variable values. Monte Carlo techniques used to introduce realistic stochastic variability improved the fit. The model was used to project a maximal rate of P removal of about 4 g P m-2 yr-1 at P loading 10-15 g P m-2 yr-1 (HLR 60-90 m yr-1). Data from the pilot wetland indicated that actual rates of P removal may prove to be higher. Further operation of the wetland at high hydraulic and P loading rates is necessary to verify or modify the application of the model.
Removal of bacterial indicators and pathogens from dairy wastewater by a multi-component treatment system
Authors: Karpiscak M.M. , Sanchez L.R. , Freitas R.J. , Gerba C.P.
Published: May 2018

Microbial removal by a multi-component treatment system for dairy and municipal wastewater is being studied in Arizona, USA. The system consists of paired solids separators, anaerobic lagoons, aerobic ponds and constructed wetlands cells. The organisms under study include: total coliform, fecal coliform, enterovirus, Listeria monocytogenes, Clostridium perfringens, coliphage, Giardia lamblia and Cryptosporidium parvum. Organism removal rates from dairy wastewater varied from 13.2 per cent for fecal coliform to 94.9 per cent for coliphage. It appears that the much higher turbidity of the dairy wastewater, nearly 1,300 NTU, decreased the treatment systems' ability to remove some microbial indicators and pathogens. Information from this study can be used to determine the adequacy of multi-component treatment systems for the control of wastewater-borne pathogens, both in municipal treatment systems as well as in confined animal feeding operations (CAFO). This information also can assist municipalities and the CAFO industry in the implementation of rational and efficient treatment strategies for appropriate reuse of wastewaters.
Cold climate wetlands: design and performance
Authors: Wallace S. , Parkin G. , Cross C.
Published: May 2018

Constructed wetlands are gaining widespread use as a simple, low cost means of wastewater treatment. Introduction of constructed wetlands technology into the northern United States has been limited by the ability of conventional wetland systems to operate without freezing during the winter. A design approach using subsurface-flow constructed wetlands covered with an insulating mulch layer has been demonstrated to prevent freezing. However, introduction of a mulch layer will affect oxygen transfer rates, pollutant removal performance, and plant establishment. These factors must be addressed for successful application of constructed wetlands technology in cold climates.
Removal of hydrogen sulphide BOD from brackish water using vertical flow wetlands in a Caribbean environment
Authors: Giraldo E. , Zárate E.
Published: May 2018

Wastewater from a 550-inhabitant community had been treated and discarded using an anaerobic filter. Due to seawater intrusion in the aquifer that supplies the water, high concentrations of hydrogen sulphide were detected in the effluent. A vertical flow wetland was designed in 1998 for treating this effluent. Four parallel reed beds with a total area of 556 m2 were constructed. During the first months of operation, a mean BOD5 removal efficiency of 91% was obtained, with loads to the wetland system up to 4g/m2/d of grease and oils (G&O). In 1999, problems of soil clogging were found due to high G&O content in the wastewater, with loads up to 15g/m2/d of G&O, which highly influenced the hydraulic conductivity of the beds, generating the clogging problems. The low hydraulic conductivity and the high effluent G&O content, caused low BOD5 and COD removal efficiencies. As G&O accumulated in the soil, the removal efficiencies decreased. Despite the clogging problems, there has been a high sulphide removal throughout the system operation. The wetlands removed sulphides successfully, under loads up to 20 gS=/m2/d. Four native species of macrophytes were planted: Paspalum penisetum, Typha sp, Conocarpres erectus and Scirpus lacustris. All of them but Typha sp. were established in the system.
Long-term performance summary for the Boot Wetland Treatment System
Authors: Martin J.R. , Keller C.H. , Clarke R.A. , Knight R.L.
Published: May 2018

The Boot WTS is a 46.5-ha, hydrologically altered cypress-gum wetland in Polk County, Florida. Poinciana Wastewater Treatment Plant No. 3 has discharged advanced secondary treated effluent to the Boot WTS since August 1984. Comprehensive operational monitoring has been ongoing since 1990. The Boot WTS has provided consistent removal of nitrogen and phosphorus. Influent total nitrogen (TN) and total phosphorus (TP) concentrations averaged approximately 10.0 mg/L and 2.5 mg/L at an average hydraulic loading rate (HLR) of 0.2 cm/d. Wetland effluent concentrations for TN and TP averaged 1.8 mg/L and 1.2 mg/L. Available flow and water quality data were used to develop estimates of the first-order removal rate, k, for TN (14 m/y) and TP (1.8 m/y). These removal rates are within the range of values for other forested treatment wetlands. Biochemical oxygen demand (2.2 mg/L) and total suspended solids (4.9 mg/L) in the influent are near background levels for forested wetlands and are not significantly reduced with passage through the system.
Stormwater treatment: do constructed wetlands yield improved pollutant management performance over a detention pond system?
Authors: Bavor H.J. , Davies C.M. , Sakadevan K.
Published: May 2018

Constructed wetland systems have been proposed as representing an improved ecotechnological option over detention basins, in terms of their abilities to reduce stormwater bacterial and nutrient loads to receiving waters. Concentrations of microbial and pollutants were determined in inflow and outflow samples collected from each type of system. Removal efficiencies for the wetland although higher than for the pond, were lower than some previously reported values for the treatment of municipal wastewater by constructed wetlands. Performance of a number of constructed wetland systems for stormwater treatment is evaluated considering the functional components of the systems.
Performance of constructed wetland system for public water supply
Authors: Elias J.M. , Salati Filho E. , Salati E.
Published: May 2018

The project is being conducted in the town of Analândia, São Paulo, Brazil. The constructed wetlands system for water supply consists of a channel with floating aquatic macrophytes, HDS system (Water Decontamination with Soil - Patent PI 850.3030), chlorinating system, filtering system and distribution. The project objectives include investigating the process variables to further optimize design and operation factors, evaluating the relation of nutrients and plants development, biomass production, shoot development, nutrient cycling and total and fecal coliforms removal, comparing the treatment efficiency among the seasons of the year; and moreover to compare the average values obtained between February and June 1998 (Salati et al., 1998) with the average obtained for the same parameters between March and June 2000. Studies have been developed in order to verify during one year the drinking quality of the water for the following parameters: turbidity, color, pH, dissolved oxygen, total of dissolved solids, COD, chloride, among others, according to the Ministry of Health's Regulation 36. This system of water supply projected to treat 15 L s-1 has been in continuous operation for 2 years, it was implemented with support of the National Environment Fund (FNMA), administered by the Center of Environmental Studies (CEA-UNESP), while the technical supervision and design were performed by the Institute of Applied Ecology. The actual research project is being supported by FAPESP.
Relationship between first-order decay coefficients in ponds, for plug flow, CSTR and dispersed flow regimes
Authors: von Sperling M.
Published: May 2018

Adequate consideration of the hydraulic regime of a pond is essential in the analysis of BOD and coliform removal, and considerable divergence exists in the literature when reporting removal coefficients. This paper aims at integrating the existing approaches, by quantifying the relationship between the first-order removal coefficients K from the three main hydraulic regimes (CSTR, plug flow and dispersed flow) adopted in the design and performance evaluation of ponds. Based on theoretical considerations and statistical regression analyses, the relationship between the K values is investigated, quantified and modelled. Two tables are presented and two equations are proposed, which allow conversion of K values obtained for dispersed flow to (a) K for CSTR and (b) K for plug flow, based on the hydraulic detention time t and the dispersion number d. These coefficients, when applied in the CSTR or plug-flow equations, will give approximately the same prediction of the effluent concentration as that obtained when using the dispersed-flow model with its proper coefficient. With this approach designers can apply, and researchers can report, K values for the two idealised flow patterns (CSTR and plug flow).
Management of a detention-settling basin using radar data and risk notion
Authors: Faure D. , Auchet P. , Payrastre O.
Published: May 2018

This paper presents a practical application of sewage network management strategy using radar data to control a detention-settling basin. This practical application, used in operational mode since January 2000, is based on three main notions. Firstly, the use of radar data without rainfall estimation. Secondly, the definition of some gradual risk levels for the sewage network by a detailed modelling of the sewage system functioning. Thirdly the definition of relations between risk levels for the sewage network and types of rain events defined from radar data. The operational application produces gradual alarms for decision-making assistance: no risk, potential risk and confirmed risk.
Selecting a probability distribution for extreme rainfall series in Malaysia
Authors: Zalina M.D. , Desa M.N.M. , Nguyen V-T-A. , Kassim A.H.M.
Published: May 2018

This paper discusses the comparative assessment of eight candidate distributions in providing accurate and reliable maximum rainfall estimates for Malaysia. The models considered were the Gamma, Generalised Normal, Generalised Pareto, Generalised Extreme Value, Gumbel, Log Pearson Type III, Pearson Type III and Wakeby. Annual maximum rainfall series for one-hour resolution from a network of seventeen automatic gauging stations located throughout Peninsular Malaysia were selected for this study. The length of rainfall records varies from twenty-three to twenty-eight years. Model parameters were estimated using the L-moment method. The quantitative assessment of the descriptive ability of each model was based on the Probability Plot Correlation Coefficient test combined with root mean squared error, relative root mean squared error and maximum absolute deviation. Bootstrap resampling was employed to investigate the extrapolative ability of each distribution. On the basis of these comparisons, it can be concluded that the GEV distribution is the most appropriate distribution for describing the annual maximum rainfall series in Malaysia.
Dissemination of regional rainfall analysis in design and analysis of urban drainage at un-gauged locations
Authors: Arnbjerg-Nielsen K. , Harremoës P. , Mikkelsen P.S.
Published: May 2018

A research program in Denmark on statistical modelling of rainfall has resulted in a model for regional distribution of rainfall extremes. The results show that extreme rainfalls critical to the hydraulic function of urban drainage systems and the pollution discharge are subject to a significant regional variation of extreme rainfalls throughout the country. This has implications for design and analysis of all practical problems related to urban drainage, since the rainfall data so far recommended as input to engineering analyses underestimates the problems. Consequently, the Danish Water Pollution Control Committee has issued a statement recommending a new engineering practice. The dissemination of the research results proved to be difficult due to lack of understanding of the concepts of the new paradigm by practitioners. The traditional means of communication was supplemented by user-friendly spreadsheets and easy access to rainfall data as well as giving courses on the new paradigm. This has eased the implementation of the new concepts greatly.
Measurement, calibration of rainfall-runoff models and assessment of the return period of flooding events at urban catchment Kumodraz in Belgrade
Authors: Despotović J. , Petrović J. , Jacimović N.
Published: May 2018

For the purpose of re-design and improvement of the combined sewer system at the Kumodraz catchment in Belgrade, measurements of rainfall and runoff at the catchment were established in late 1997. Observed data are used for calibration and validation of two rainfall-runoff models: the detailed model BEMUS (Belgrade Model) and a conceptual hydrologic model Visual OTTHYMO. The major facilities of the recommended solution for re-design of the existing system are three retention ponds and outlet into a trunk. The paper briefly presents assessment of design flows for these four locations of the catchment based on results from the calibrated models. Data on intense storms that caused severe flooding within the catchment (and also all over Belgrade and other parts of Serbia) in June and July 1999 are used for comparison of design flows with a real event. During these storms the flow gauging equipment at the catchment was destroyed and only the rainfall data was available. In order to analyze the system under extreme conditions it is therefore necessary to perform hydrograph simulations. The basic idea was to check return periods of rainfall and runoff for these storms.
Mass spectrometric monitoring of the degradation and elimination efficiency for hardly eliminable and hardly biodegradable polar compounds by membrane bioreactors
Authors: Schröder H.Fr.
Published: May 2018

Wastewaters containing or spiked with polar compounds - alkylphenolethoxylates (APEOs) and drugs - were treated in membrane-assisted and conventional biological pilot plants to eliminate these pollutants. Elimination resulting in metabolization or ultimate degradation was pursued by substance-specific analysis applying atmospheric pressure chemical ionization (APCI) in combination with mass and tandem mass spectrometric detection (MS and MS-MS) either in the flow injection (FIA) or liquid chromatographic separation (LC) mode. APEOs were diminished by successive cleavage of polyether chain links resulting in short chain APEOs or alkylphenols (AP), if the biocoenosis was adapted to the compounds. Lipid regulating agents (LRA) were either eliminated completely (etofibrate), metabolized to fenofibratic acid (fenofibrate) or diminished to a minimal extent (bezafibrate). Compared to the membrane microfiltration process the conventional activated sludge process was less successful in both APEO and LRA elimination.
PCB sources and degradation in sediments of Ashtabula River, Ohio, USA, determined from receptor models
Authors: Imamoglu I. , Li K. , Christensen E.R.
Published: May 2018

The PCB pollution in Ashtabula River sediments was evaluated using a factor analysis (FA) model with non-negative constraints, and a chemical mass balance (CMB) model. The FA model identified Aroclor 1248 as the major PCB source, and also a congener pattern significantly different from that of any Aroclor. The CMB model that uses linear combinations of Aroclors, failed to reproduce the sample congener profiles with good statistical fit. The findings from both models indicate that the PCBs in Ashtabula River sediments have undergone significant alterations changing their profiles from those of the original sources. These alterations may be explained by the anaerobic dechlorination of highly chlorinated congeners, according to dechlorination activities H/H'.
Analysis of scenarios for sewerage, wastewater treatment and prioritised load on environment from the Greater City of Copenhagen
Authors: Harremös P. , Andersen H.S. , Dupont R. , Jacobsen P. , Rindel K.
Published: May 2018

The sewer system for the Greater Copenhagen area covers an area of 4460 ha contributing to the runoff. The total area serves in total 8 municipalities, however it is dominated by the areas in the City of Copenhagen proper. The catchments merge into interceptors, which feed two large treatment plants. The effluent from the two treatment plants discharges during dry weather to Øresund, the sound between Denmark and Sweden. This large system has been analysed for selected scenarios with respect to handling runoff in an optimal way in order to minimise the loads on the most sensitive receiving waters and optimising treatment plant performance.
Real time control of the integrated urban wastewater system using simultaneously simulating surrogate models
Authors: Meirlaen J. , Van Assel J. , Vanrolleghem P. A.
Published: May 2018

The urban wastewater system (sewer and treatment plant) has a major impact on the river water quality of urban streams. To minimise this impact, real time control is a valuable option. Since the ultimate goal of any control strategy is to optimise the quality of the river system, it is useful to take pollutant immissions into account when determining the control strategy and/or the setpoints of the controller. However, a simultaneously simulating model of the complete system is needed in order to allow design and evaluation of such control strategies.

In this work an integrated model of the urban wastewater system is created. This has been accomplished by implementing surrogate models of the three subsystems within a single software platform. The coupled submodels are subsequently used in a semi-hypothetical case study to optimise the resulting river water quality. An ammonia sensor in the river has been used to control the amount of water treated biologically in the treatment plant. It was shown that this integrated control could lower the peak ammonia concentration in the part of the river downstream of the treatment plant. Hence, a proof of principle has been given that the use of measurements in the river to perform control actions in the sewer system and the treatment plant is a promising option.
Wet weather water quality modelling of a Portuguese urban catchment: difficulties and benefits
Authors: David L.M. , Matos R.S.
Published: May 2018

This paper discusses the use of water quality deterministic modelling together with an integrated approach to assess the impact of urban stormwater discharges into ephemeral watercourses, based on the study of a Portuguese catchment. The description of the main aspects, difficulties and benefits found during data collection and model calibration and verification is presented, and the associated uncertainties and errors discussed. Experimental results showed a strong short- and long-term impact of sewer discharges on rivers, and confirmed deposition, resuspension and transport of pollutants as important processes for the water quality. However, the resuspension of riverbed sediment pollutants during storms was probably more significant than the direct impact of the urban discharges. The HydroWorks™ model was used since it allows for the calculation of pollutant build-up on catchment surfaces and in gully pots, their wash-off, and the deposition and erosion of sediments in sewers. However, it uses several constants, which could not be independently calibrated, increasing the uncertainty already associated with the data. River flows have quite different magnitude from the sewer system overflows, which, together with the difficulties in evaluating river flow rates, makes the integrated modelling approach rather complex and costly.
Criteria for assessment of the operational potential of the urban wastewater system
Authors: Schütze M. , Butler D. , Beck M.B. , Verworn H.-R.
Published: May 2018

Application of real-time control (RTC) is one possible measure to increase the performance of the urban wastewater system. However, the potential and the benefits of control depend strongly on the characteristics of the individual site under question. Conventionally, to evaluate this potential, a detailed feasibility study had to be carried out. In some cases, such a study may well conclude that, for the given site, real-time control does not have any significant potential, thus resulting in unnecessarily having spent precious resources for a detailed study. It would be desirable to have a methodology that allows simple, and cost-effective, screening of sites for which the analysis of real-time control may be beneficial. Earlier research led to the provision of an easy-to-apply scoring system which allows a quick assessment of the RTC potential of controlling flow in sewer systems. However, since this procedure does not take into account water quality aspects, or the treatment plant or the receiving water body, it cannot be used for assessing the potential of RTC of the complete system, let alone for integrated RTC. This paper describes the first part of an on-going project which aims at establishing an enhanced procedure for assessing the real-time control potential for the entire urban wastewater system. After providing a definition of the term “RTC potential”, a large number of (partly hypothetical) case studies (varying a number of key parameters of the wastewater system) is simulated, using the simulation tool SYNOPSIS. For each of these sites, a number of real-time control algorithms are developed and optimised, following a general procedure, which allows for local, global and integrated scenarios to be considered. Analysis of the results reveals those system parameters which are of particular significance to the RTC potential of urban wastewater systems. These are discussed and assessed in this paper. Furthermore, the results of a simulation study are provided which indicate a clear potential of integrated control even for many case studies for which local control provides hardly any benefits. Subsequent studies will complement the simulation study by comparison with a number of real case studies in various countries.
Bayesian decision analysis as a tool for defining monitoring needs in the field of effects of CSOs on receiving waters
Authors: Korving H. , Clemens F.
Published: May 2018

In recent years, decision analysis has become an important technique in many disciplines. It provides a methodology for rational decision-making allowing for uncertainties in the outcome of several possible actions to be undertaken. An example in urban drainage is the situation in which an engineer has to decide upon a major reconstruction of a system in order to prevent pollution of receiving waters due to CSOs. This paper describes the possibilities of Bayesian decision-making in urban drainage. In particular, the utility of monitoring prior to deciding on the reconstruction of a sewer system to reduce CSO emissions is studied. Our concern is with deciding whether a price should be paid for new information and which source of information is the best choice given the expected uncertainties in the outcome. The influence of specific uncertainties (sewer system data and model parameters) on the probability of CSO volumes is shown to be significant. Using Bayes' rule, to combine prior impressions with new observations, reduces the risks linked with the planning of sewer system reconstructions.
Cost benefit risk – a concept for management of integrated urban wastewater systems?
Authors: Hauger M.B. , Rauche W. , Linde J.J. , Mikkelsen P.S.
Published: May 2018

Urban wastewater systems should be evaluated and analysed from an integrated point of view, taking all parts of the system, that is sewer system, wastewater treatment plant and receiving waters into consideration. Risk and parameter uncertainties are aspects that hardly ever have been addressed in the evaluation and design of urban wastewater systems. In this paper we present and discuss a probabilistic approach for evaluation of the performance of urban wastewater systems. Risk analysis together with the traditional cost-benefit analysis is a special variant of multi-criteria analysis that seeks to find the most feasible improvement alternative for an urban wastewater system. The most feasible alternative in this context is the alternative that has the best performance, meaning that the alternative has the lowest sum of costs, benefits and risks. The sum is expressed as the Net Present Cost (NPC). To use NPC as a decision variable has the problematic effect, that two alternatives performing completely differently when focusing on environmental cost can have the same NPC. The extreme example is one alternative with high risk and low cost and another with low risk and high cost. In this example it is up to the decision-maker to decide whether she wants to spend the budget on preventive installations or cleaning up after failures in the environment.
Effective environmental regulation to maximise the benefits of integrated wastewater management
Authors: Crabtree B. , Morris G.
Published: May 2018

On the 25 November 1999, the Secretary of State for the Environment in England and Wales announced the outcome of the water companies' third Periodic Review. As a result, a major environmental investment programme will be completed during the period 2000/2005. Overall in England and Wales, it is planned that almost 3,600 km of rivers will be protected or improved and 3,800 unsatisfactory CSOs will be improved to allow receiving water objectives to be met. This means that over the next 5-year period an average of nearly 18 discharges will be improved every week. The implementation of the programme will involve a large workload for the Environment Agency in planning and authorising the individual schemes for delivery by the water companies. The paper illustrates how the Urban Pollution Management procedure and associated environmental standards are to be used to underpin the Environment Agency's policy, to encourage the use of integrated wastewater planning and, as a result, ensure that the anticipated environmental improvements will be delivered.
Measurement of microorganisms with PHA production capability in activated sludge and its implication in Activated Sludge Model No. 3
Authors: Hanada S. , Satoh H. , Mino T.
Published: May 2018

In Activated Sludge Model No.3 (ASM3), it is hypothesized that all heterotrophic microorganisms (XH) can store substrate. However, in reality, both microorganisms with and without substrate storage capability (XH/STO and XH/S, respectively) could exist. If the ratio of XH/STO in activated sludge is influenced by operational and environmental conditions, kSTO (storage rate constant of heterotrophic microorganisms which is defined in ASM3) may not be a universal parameter and can change from case to case. In this study, polyhydroxyalkanoate (PHA) is assumed as the principal storage product, and the ratio of microorganisms with PHA production capability (XH/PHA) in various activated sludges was estimated by the dual staining of Nile Blue A (NB) and DAPI. It was shown that the ratio of XH/PHA in sludge varied among different municipal and laboratory activated sludges.
Optimization of activated sludge designs using genetic algorithms
Authors: Doby T.A. , Loughlin D.H. , de los Reyes F.L. , Ducoste J.J.
Published: May 2018

We describe a framework in which a genetic algorithm (GA) and a static activated sludge (AS) treatment plant design model (WRC AS model) are used to identify low cost activated sludge designs that meet specified effluent limits (e.g. for BOD, N, and P). Once the user has chosen a particular process (Bardenpho, Biodenipho, UCT or SBR), this approach allows the parameterizations for each AS unit process to be optimized systematically and simultaneously. The approach is demonstrated for a wastewater treatment plant design problem and the GA-based performance is compared to that of a classical nonlinear optimization approach. The use of GAs for multiobjective problems such as AS design is demonstrated and their application for reliability-based design and alternative generation is discussed.
Combined hydraulic and biological modelling and full-scale validation of SBR process
Authors: Keller J. , Yuan Z.
Published: May 2018

The biological reactions during the settling and decant periods of Sequencing Batch Reactors (SBRs) are generally ignored as they are not easily measured or described by modelling approaches. However, important processes are taking place, and in particular when the influent is fed into the bottom of the reactor at the same time (one of the main features of the UniFed process), the inclusion of these stages is crucial for accurate process predictions. Due to the vertical stratification of both liquid and solid components, a one-dimensional hydraulic model is combined with a modified ASM 2d biological model to allow the prediction of settling velocity, sludge concentration, soluble components and biological processes during the non-mixed periods of the SBR. The model is calibrated on a full-scale UniFed SBR system with tracer breakthrough tests, depth profiles of particulate and soluble compounds and measurements of the key components during the mixed aerobic period. This model is then validated against results from an independent experimental period with considerably different operating parameters. In both cases, the model is able to accurately predict the stratification and most of the biological reactions occurring in the sludge blanket and the supernatant during the non-mixed periods. Together with a correct description of the mixed aerobic period, a good prediction of the overall SBR performance can be achieved.
Fine sediment retention in storage chambers: an assessment of time-dependent effects
Authors: Stovin V.R. , Grimm J.P. , Saul A.J.
Published: May 2018

The optimisation of the design of a storage chamber is generally based upon some measure of the chamber's sedimentation efficiency. In the UK, chambers that minimise the deposition of fine sediments are preferred. Previous laboratory and CFD-based studies to measure efficiency have focused on steady flow conditions. However, both the flow hydraulics within a storage chamber and the pollutant loading in the incoming sewage vary markedly during storm events. This paper outlines a CFD-based approach for determining “overall” chamber efficiency. The approach employs an unsteady volume-of-fluid multiphase model and stochastic particle tracking. Preliminary results from a simplified two-dimensional model are presented.
Innovative technologies for wastewater treatment in coastal tourist areas
Authors: Orhon D. , Sekoulov I. , Dulkadiroglu H.
Published: May 2018

The selection of appropriate wastewater treatment technologies for coastal tourist areas is important in the sense that they have to meet stringent effluent limits in a simple and easy to operate flow scheme. This paper outlines different effluent standards implemented in sensitive coastal areas and briefly discusses the merit of a number of innovative technologies, namely the sequencing batch reactor, the intermittent aeration process, the moving bed reactor and the biofim-filter-sequencing batch reactor system, either as a batch or continuous flow process applicable in these areas.
Membrane dosing units for chemicals in water and wastewater treatment plants
Authors: Kouzmanova K. , Michailov G. , Sekoulov I.
Published: May 2018

It is well known that in the practice of the drinking water as well as of the wastewater treatment especially for the processes of pH-regulation, flocculation, precipitation or disinfection, the dosing of reagents is necessary. The costs of the automatic dosing stations are comparatively high. For the smaller water treatment plants these stations are uneconomical and charged with maintenance problems very often. In many cases the frequently observed highly fluctuating reagents needs and the recess between can cause disruption of the normal exploitation work. These disadvantages can easily be overcome by a device based on permeable or semi-permeable membranes. The use of semi-permeable membranes is favourable especially in the cases of fluctuating water quantities or standstills. It can be effective because of the possibility for their self-regulation during the dosing. When there is no inflow available some kind of concentration equilibrium is established between the internal and external membrane layers. This system is easy to install and it can be easily adapted to the local conditions. The device can be a canister filled with the desired reagent and covered with a lid of a definite semi-permeable membrane. After determining the permeability of the membranes made of different materials only the appropriate membrane area is important to be determined. Developed methods for defining the specific membrane permeability are discussed in the paper. Suggestions for the application of such devices in practice are given as well.
Seasonal changes of nutrients and oxygen in the Bulgarian Black Sea coastal area
Authors: Shtereva G. , Krastev A. , Hristova O.
Published: May 2018

The paper discusses the seasonal dynamics of nutrients and oxygen during the period 1995-1998 in comparison to the previous periods. This study is based on monthly and seasonally monitoring in the 3-20 n.m. zone along the Bulgarian Black Sea area. The investigation reveals certain shifting of seasonal maximums (minimums) and a trend of decreasing oxygen saturation, phosphorus and silicon in the last few years.
Implementing GIS to resolve environmental coastal problems in Varna
Authors: Dimov L.N.
Published: May 2018

The city of Varna, like many other coastal cities along the Black Sea and Mediterranean Sea, has a lot of problems related to the environmental protection for many years, including those with coastal zone management. Recently, the coastal slope problems due to land-slides apeared as very urgent and difficult to be solved. This paper describes a method to solve some of the problems by analysing the data collected. A data layer representing the complete hydrologic network including transport lines through slopes, lakes, streams, rivers, is a necessary component of many hydrologic and coastal applications. The coastal area of the city has significant importance - sea ports, resorts, cargo terminals. Most of them add environmental problems to the Black Sea in adjacent territories and the region as a whole. The attempt described is to solve these problems on the ground.

This paper describes a process to analyse the area specific geographical data for a decision. Making a front-end application using ESRI's ArcView 3.0a/Avenue, user-friendly procedures were prepared to automate most of the functions. This application generates maps using data collected during the last two years. The data acquisition is performed according to the Bulgarian standards. Converting procedures are created and tested as well. Finally, a technology for updating data is approved.
Vulnerability of groundwater to pollution from agricultural diffuse sources: a case study
Authors: Muhammetoğlu H. , Muhammetoğlu A. , Soyupak S.
Published: May 2018

Kumluca, near Antalya in Turkey, is an important plain with its intensive agricultural activities employing greenhouses. The chemical fertilizer application practices caused excessive increases of the nitrogen, phosphorus and salinity within groundwater. A study has been initiated to assess the present state of the groundwater pollution problem of Kumluca Plain. A total of nine measurement and sampling stations have been selected to represent different depths groundwater table, different types of agricultural activities and different soil types. The magnitudes of the parameters: temperature, salinity and conductivity, nitrate, nitrite, ammonia, orthophosphate and fecal coliform were determined for groundwater. Soil samples collected from the stations have been analyzed for several parameters such as texture, total salinity, total nitrogen, and total phosphorus. The measurement and analyses results of the groundwater showed wide spatial variations depending on factors such as the quality of irrigation water, depth groundwater, soil characteristics, type and age of agriculture and hydrology. Groundwater vulnerabilities to pollution have been analyzed using the SEEPAGE Model approach. Furthermore the soil, aquifer and groundwater characteristics, which will be utilized to establish “cause” and “effect” relationships in future, have been clarified.