bluuebunny/crossref_metadata_2025 huggingface dataset:
Polyphosphate kinase genes from activated sludge carrying out enhanced biological phosphorus removal
Authors: McMahon K.D. , Jenkins D. , Keasling J.D.
Published: May 2018

The community structure and metabolic function of activated sludge carrying out enhanced biological phosphorus removal have been investigated. Laboratory-scale sequencing batch reactors were operated at several influent COD/P ratios to obtain sludges with a range of phosphorus contents. Molecular microbiological techniques based on small subunit ribosomal RNA were used to characterize the community structure of these sludges. The dominant polyphosphate accumulating organism was a close relative of Rhodocyclus tenuis, a member of the β subclass of the Proteobacteria. Fragments of genes coding for polyphosphate kinase (PPK), thought to be responsible for polyphosphate accumulation, were retrieved from one of the sludges. The relative abundance of PPK gene copies in genomic DNA extracted from sludges was determined to confirm that at least one of the PPK gene sequences was derived from the dominant polyphosphate accumulating organism.
Role of “G-bacteria” in anaerobic substrate uptake in a SBR with no phosphorus removal
Authors: Kong Y.H. , Beer M. , Seviour R.J. , Lindrea K.C. , Rees G.A.
Published: May 2018

Biomass from an SBR running with no enhanced biological phosphorus removal (EBPR) but which exhibited anaerobic assimilation of glucose and acetate, was dominated by “G-bacteria”, cocci in tetrads and clusters. Extracted 16S rDNA was amplified by PCR and then analysed using Denaturing Gradient Gel Electrophoresis (DGGE). Major bands were extracted and their sequences determined. Clone libraries were also prepared, the 16S rDNA extracted, PCR performed and the resultant fragments run by DGGE to aid in identifying the DGGE bands and provide fuller sequences than available by DGGE alone. The two approaches together allowed several bands to be identified. Probes for FISH analyses were designed for some of these in attempts to see to which phylogenetic group “G-bacteria” belonged, and whether they represented the dominant bands detected by DGGE. Then FISH/Microautoradiography (MAR) was used in attempts to see which bacteria there were assimilating substrates anaerobically. Results indicated that the “G-bacteria” were phylogenetically diverse, but mainly α-proteobacteria and members of the high G+C% Gram-positive bacteria. Not all of these could assimilate glucose and/or acetate anaerobically, and Amaricoccus, the original “G-bacteria” of Cech and Hartman, was not detected.
Simulation of biofilm growth, substrate conversion and mass transfer under different hydrodynamic conditions
Authors: Horn H. , Wäsche S. , Hempel D.C.
Published: May 2018

The hydrodynamic conditions and the substrate load in biofilm systems are two main parameters which influence the biofilm growth in particular the structure, density and thickness. In a long term study on heterotrophic biofilms in biofilm tube reactors the investigation has focussed on mass transfer at the bulk/biofilm interface, the biofilm density and the substrate conversion rates. To study the mass transfer phenomena at the bulk/biofilm interface oxygen profiles have been measured directly in tube reactors with microelectrodes. Microelectrode studies, substrate conversion rates and biofilm densities were used to formulate model equations for the simulation of biofilm growth under different hydrodynamic and substrate conditions. It can be shown that the mass transfer at any time is strongly coupled with the growth conditions during the biofilm cultivation. On the one side the calculated Sherwood numbers were coupled to the present hydraulic conditions, on the other side in addition the growth conditions such as growth rate and Reynolds number during biofilm cultivation were considered.
Benchmarking nitrogen removal suspended-carrier biofilm systems using dynamic simulation
Authors: Vanhooren H. , Yuan Z. , Vanrolleghem P.A.
Published: May 2018

We are witnessing an enormous growth in biological nitrogen removal from wastewater. It presents specific challenges beyond traditional COD (carbon) removal. A possibility for optimised process design is the use of biomass-supporting media. In this paper, attached growth processes (AGP) are evaluated using dynamic simulations. The advantages of these systems that were qualitatively described elsewhere, are validated quantitatively based on a simulation benchmark for activated sludge treatment systems. This simulation benchmark is extended with a biofilm model that allows for fast and accurate simulation of the conversion of different substrates in a biofilm. The economic feasibility of this system is evaluated using the data generated with the benchmark simulations. Capital savings due to volume reduction and reduced sludge production are weighed out against increased aeration costs. In this evaluation, effluent quality is integrated as well.
Go or no go for gel entrapped nitrifiers? A Belgian case study
Authors: Geenens D. , Jonkers C. , Thoeye C.
Published: May 2018

In the coming years, as stricter environmental requirements are imposed, many European Union wastewater treatment plants (WWTP) need to be expanded and/or upgraded. This requires considerable investments. Optimising the renovation recourses can lead to significant savings. The use of entrapped nitrifying bacteria for upgrading of WWTP towards nutrient removal may be benificial. Long term pilot tests were performed to evaluate a so-called pellet reactor. Differences in performance and microbiological composition of classical activated sludge and the pellet reactor were investigated. FISH analyses showed (i) absence of Nitrobacter cells and (ii) high abundance of Nitrospira in the pilot reactors. Two Belgian WWTP make use of fine bubble aeration and could – theoretically – easily be renovated towards nitrogen removal using encapsulated nitrifiers. Financial aspects are commented on.
Microthrix parvicella foaming at the Fusina WWTP
Authors: Miana P. , Grando L. , Caravello G. , Fabris M.
Published: May 2018

The Fusina WWTP receives civil and industrial wastewater from Venice and its hinterland. Its treatment capacity is in the range of 4,000–5,000 m3/h. In winter the Fusina WWTP is subjected to brown and viscous foams developed on the surface of the aeration basins and of the clarifiers. The microscopic observation of biological foams and activated sludge samples showed high concentration of the filamentous organism Microthrix parvicella. This paper investigates the growth of M. parvicella from January 1998 to January 1999 and relates it to foams developed on the aeration basins and clarifiers, to temperature, surfactants, BOD5, NH4, NO3, NO2, DO, PO4 and pH of the wastewater influent, to SVI and the other species of filamentous organisms of mixed liquor. The results demonstrate the strong connection of the foams developed with M. parvicella abundance, the synergic action with surfactants, the dependence of M. parvicella on temperature and no relation to the other chemical and physical parameters investigated.
A full scale application in the control of the filamentous bulking generated by Type 021N F. thiothrix sp.
Authors: Guida M. , Cesàro G. , Lipardi I.L. , Melluso G.
Published: May 2018

The presence of industrial effluent in the wastewater incoming to municipal activated sludge treatment plants sometimes causes bulking events. In order to control one of these events a strategy of bacterial selection was applied with an anoxic selector before the main oxidation basin utilising the screw pumps basin. The result of this work confirms what is reported in the literature about the possibility to utilize a metabolic control of some filamentous forms (particularly Type 021N) with high organic load. The remedial action could be realized using already existing facilities, without any additional costs.
Anaerobic sequencing batch reactor as initiating stage in complete pentachlorophenol biodegradation
Authors: Ribarova I. , Topalova J. , Ivanov I. , Kozuharov D. , Dimkov R. , Cheng C.
Published: May 2018

Biodegradation of pentachlorophenol (PCP) has been studied in a sequence of two completely mixed reactors. Investigation on the first anaerobic sequencing batch reactor (AnSBR) is discussed in detail in this paper. Key technological and microbiological features were studied: two different types of adaptation process of anaerobic sludge towards PCP detoxication; the influence of the sludge concentration upon the rate of PCP biodegradation; minimum retention time for PCP degradation in dependence on the PCP concentration; modeling of the PCP degradation process; effluent COD and SS concentrations; changes in the micro- and macrostructure of the sludge during acclimatization process.
Fuzzy predictive control for nitrogen removal in biological wastewater treatment
Authors: Marsili-Libelli S. , Giunti L.
Published: May 2018

Whenever the carbon/nitrogen ratio of a domestic wastewater is too low, full denitrification is difficult to obtain and an additional source of organic carbon has to be provided. Since loading conditions may vary appreciably over the diurnal cycle, depending on the weather and sewage conditions, dosing should be controlled by an adaptive regulator to keep into account the time-varying process dynamics. A fuzzy predictive controller is proposed in this paper and its performance is tested through numerical simulations. The new aspects brought forward are the use of an improved model for denitrification, the use of benchmark (i.e. thoroughly tested and standardised) input files and the conclusion about regulator performance in overall plant performance, in terms of carbon saving and discharge compliance.
Control of the aeration volume in an activated sludge process for nitrogen removal
Authors: Samuelsson P. , Carlsson B.
Published: May 2018

Biological nitrogen removal in an activated sludge process is obtained by two biological processes; nitrification and denitrification. Nitrifying bacteria need dissolved oxygen and a sufficiently large aeration volume for converting ammonium to nitrate in the wastewater. The objective of this paper is to develop an automatic control strategy for adjusting the aerated volume so that the effluent ammonium level can be kept close to a desired value despite major changes in the influent load. The strategy is based on applying exact linearization of the IAWQ Activated Sludge Process Model No 1. Simulation results show that the suggested controller effectively attenuates process disturbances.
Biological detoxification of tar-water
Authors: Jansen J. la C. , Jönsson K. , Hagman M.
Published: May 2018

Gasification is an important option for the swift implementation of biomass combined heat and power processes in the Danish energy supply system. Tar-water produced by the gas-cleaning system of gasifiers may contain substances toxic to nitrifying bacteria. As the gasification plants are small and often located in the catchment area of small wastewater treatment plants, discharge of the tar-water may be critical for wastewater treatment plants operated with nitrogen removal. Tar-water from a full-scale updraft gasifier has been thoroughly examined with respect to inhibition of nitrification and the toxicity for nitrifying bacteria has been evaluated for the dominating constituents in the tar-water. Simple organic substances make up the dominating part of the organic matter but phenol and phenolic compounds are also present in significant concentrations. The identified substances are biologically degradable and it has been demonstrated that most of the organic matter together with the toxicity can be eliminated in an aerobic activated sludge process.
In-situ measurement of ammonium and nitrate in the activated sludge process
Authors: Rieger L. , Siegrist H. , Winkler S. , Saracevic E. , Votava R. , Nadler J.
Published: May 2018

A new in-situ probe is presented for the continuous measurement of ammonium and nitrate in wastewater. It requires no sample preparation and is installed directly in the process liquid. This new low-cost probe significantly reduces investment and operating costs and requires minimum maintenance. The paper describes the sensor principle and test results from three different probe locations: the primary clarifier effluent, the activated sludge tank and the nitrifying biofilter influent. Reference measurements were carried out by means of conventional analyzers with ultrafiltration, an in-situ UV spectrometer for the nitrate and laboratory analysis of spot and 2h-composite samples. The aim of the study was to investigate the operational reliability and accuracy of the new probe and the expenditure required for its maintenance and calibration. The tests showed that the new probe performed very well overall and required minimum maintenance. Some problems were observed during the biofilter plant test. They are assumed to be related to substantial changes in the wastewater composition.
Wastewater treatment benchmark: what can be achieved with simple control?
Authors: Vrečko D. , Hvala N. , Kocijan J.
Published: May 2018

In this paper a simple control strategy is applied to and assessed on the wastewater treatment benchmark. The controllers used in the presented control strategy are PI controllers, feedforward control and a step-feed procedure. The controlled variables are not directly the effluent concentrations but other process variables which have an effect on the effluent. The setting of set-points is also analyzed to select the values with the best performance. Set-point analysis has shown that with an optimal setting of set-points under stormy influent conditions, the achieved plant performance is also retained for rainy and dry influent conditions. The evaluation of plant performance indicates that with the proposed control strategy, a lower number of effluent violations has been achieved, as well as lower energy consumption and lower sludge production, when compared to results published up to now. Only the effluent quality criterion deteriorated.
Exploiting online in-situ ammonium, nitrate and phosphate sensors in full-scale wastewater plant operation
Authors: Ingildsen P. , Olsson G.
Published: May 2018

In-situ nutrient sensors are now a proven technology. Having ion membranes eliminates the need for ultrafiltration, and consequently the sensors can be located at suitable places in any of the reactors. This gives the potential for new control structures for the control of nitrification, denitrification, and phosphorus removal. In the paper some examples of such controllers are demonstrated as used in a full-scale wastewater treatment plant. A successful control implementation scheme at full-scale plants includes three steps: monitoring, experimenting and controlling. The benefit of implementing process control based on nutrient sensors is real: by implementing precipitation dosage control a savings of 41% compared to flow proportional dosage can be reached, while the savings compared to constant dosage is 73%. An increase in nitrate recirculation shows significant improvement in the nitrogen removal ability at very low cost. Reliable nutrient sensors are not the only prerequisite for a successful control system. The design of actuators, such as drives, compressors and valves, is often overlooked. Furthermore, the lower level controllers have to work properly before the more advanced controllers can work adequately. A collection of practical experience regarding such issues is given in this paper.
Environmental factors contributing to the “G bacteria” population in full-scale EBPR plants
Authors: Griffiths P.C. , Stratton H.M. , Seviour R.J.
Published: May 2018

A survey of several enhanced biological phosphorus removal (EBPR) plants within Australia has demonstrated that a group of bacteria known as the “G” bacteria are able to proliferate under a broad range of plant configurations. The diverse designs and operational parameters of these plants did not permit definitive determination of the factor(s) contributing to the proliferation of G bacteria. Two plants were monitored over time to assess the G bacteria and phosphorus accumulating organisms (PAO) populations in relation to key operational parameters. The mixed liquor biomass and operational parameters were compared to other plants successfully and unsuccessfully reducing phosphorus from the wastewater. Two critical factors recognised in this study were the dissolved oxygen concentration in the aerobic zone and the type and amount of carbon source in the anaerobic zone.
Combined denitrification and excess biological phosphorus removal in discontinuous operated biofilm systems
Authors: Brandt D. , Sieker C. , Hegemann W.
Published: May 2018

The sorption-denitrification-P-removal (S-DN-P) process combines biological excess P-removal (BEPR) and denitrification using immobilized biomass. The accumulation of denitrifying polyP organisms is achieved by sequencing anaerobic/anoxic conditions. The immobilized biomass is in alternating contact with primary treated wastewater (anaerobic sorption-phase) and nitrified wastewater (denitrification phase). In the sorption phase, P-release takes place and readily biodegradable organic substrate, e.g. volatile fatty acid, is taken up and stored by polyP accumulating organisms (PAO). In addition to this, other organic matter is physically/chemically adsorbed in the biofilm structures. In the denitrification phase, the biomass denitrifies the stored and adsorbed organic substrate and, at the same time, P-uptake and polyP formation occurs. This paper presents results of investigations at laboratory and half-technical scale. At laboratory scale different types of carriers were tested regarding their suitability for the S-DN-P-process. In half-technical scale a biofilter and a moving bed reactor (MBR) were tested. In the biofilter a stable removal of nitrate and phosphate was achieved. However, it was not possible to achieve similar results in the MBR process. Especially the release and uptake of phosphate showed no clear tendency although the uptake of acetate was good. Reasons for this could be the accumulation of glycogen accumulating organisms which impair the metabolism of PAO.
Effects of volatile fatty acids on a thermophilic anaerobic hydrogen fermentation process degrading peptone
Authors: Cheng S.-S. , Chang S.-M. , Chen S.-T.
Published: May 2018

Hydrogen fermentation using glucose as a single substrate caused abrupt pH drops and the gradual losses of hydrogen producers, which in turn led to system failure. In this study the use of a proteinaceous substrate, peptone, avoided the abrupt pH drops in the reactive system and allowed for further exploration of volatile fatty acids (VFAs) and pH effects on the hydrogen fermentation process. Our results showed that: (1) during the hydrogen fermentation tests, the abrupt pH drops were avoided thus system stability increased due to the production of ammonia from the peptone fermented, (2) pH control was not necessary and the addition of acetate to the process had little effect on the hydrogen fermentation process, (3) at the extreme pHs the addition of acetate either lengthened the lag phase (pH ≤6) or slowed the hydrogen production rate (pH ≥ 8), and both situations were not desired, and (4) high VFA content in the system sped up the consumption of hydrogen gas. Results of this study suggested that the hydrogen fermentation using the protein-containing substances as substrate was beneficial in maintaining the system pH. As long as the pH was maintained around 6-8, system inhibition due to VFAs accumulation was minimized. Thus, the optimal operation of a hydrogen fermentation process would be achievable via the control of substrate composition at a certain carbohydrate-to-protein ratio.
Improved split feed anaerobic baffled reactor (SFABR) for shorter start-up period and higher process performance
Authors: Uyanik S. , Sallis P.J. , Anderson G.K.
Published: May 2018

In this paper, the Split Feed Anaerobic Baffled Reactor (SFABR) is introduced and investigations into the use of modified seed material are described. It was shown that shorter and reliable start-up times could be achieved with SFABR when using improved seed material, even for the treatment of particularly problematic wastewater, i.e. ice-cream wastewater. Scanning electron photo-micrographs (SEM) revealed that granulation process occurs relatively rapidly in the SFABR compared with other reactor configurations, and that the reactor contained a highly mixed population of methanogens in all compartments. The use of polymer-conditioned anaerobic sludge and granular sludge as seed proved advantageous over the use of suspended growth anaerobic sludge, and the “improved” SFABR consequently performed more efficiently and also showed greater stability than the conventional ABR.
Optimal operation for timely adaptation of activated sludge plants to changes in the surfactant composition of wastewater
Authors: Carvalho G. , Novais J.M. , Vanrolleghem P.A. , Pinheiro H.M.
Published: May 2018

The composition of a textile industry wastewater is highly variable, as the industrial process has to follow fashion and season trends. Surfactants represent one of the largest COD fractions in a typical textile wastewater. Therefore, it was the aim of this paper to model the acclimatisation behaviour of an activated sludge system when subjected to composition variations in the surfactant containing feed. The model was based on data obtained in SBR experiments in which a linear alkyl ethoxylate as sole carbon source in the feed was replaced by another with a longer ethoxylate chain. A previously developed model (Fractionated Degradation Model) was applied to each of the 21 SBR cycles carried out in this study. The resulting best-fit parameters were investigated and sub-models were further developed, to create an acclimatisation model, able to predict the sludge acclimatisation level. Using the information given by this model, it was possible to propose an optimal operation scheme to pre-acclimatise the sludge before a surfactant replacement is made in the textile process. A cost analysis was carried out to compare different scenarios, with and without the application of this operation scheme. It was concluded that the proposed pre-acclimatisation process may be cost effective as compared to other scenarios if a cheap surfactant-containing product was employed.
Regional planning and product recovery as tools for sustainable sludge management
Authors: Stypka T. , Plaza E. , Stypka A. , Trela J. , Hultman B.
Published: May 2018

The article presents two aspects of sludge management: regional planning and product recovery. The introduction of these two elements can reduce the cost, close the ecocycle and make the management more sustainable. A spreadsheet program to optimize the regional location of different facilities is presented. The simple example shows the potential of the model. The brief comparison of formal problems concerning sludge disposal in Poland and Sweden is also discussed. Requirements of phosphorus recovery and recycling of phosphorus to the phosphate industry make sludge fractionation in combination with product recovery a new development in wastewater handling. Phosphorus recovery from sludges with chemical bound phosphorus requires complex and expensive process technology and may therefore lead to increased regional sludge management with a central sludge treatment plant.
Online load measurement in combined sewer systems – possibilities of an integrated management of waste water transportation and treatment
Authors: Häck M. , Lorenz U.
Published: May 2018

To obtain a further appreciable reduction of discharges in the area of sewage disposal, besides waste water purification at our treatment plants, discharge of wastewater through the sewer system has to be taken into account. Today, control strategies pursuing this aim are mainly based on hydraulic conditions like level or flow rate. They all neglect the wastewater organic load as an essential parameter. The main reasons are the expensive methods used to continuously measure traditional organic sum parameters like COD or TOC. A meaningful alternative to those parameters is the spectral absorption coefficient at λ = 254 nm (SAC), defined in DIN 38402 by the German Institute for Standardisation. As a purely physical parameter, the SAC shows a good correlation to organic sum parameters like COD and TOC, especially if municipal wastewater is considered. By using an UV-process probe, it is possible to measure the SAC and infer the organic load of raw wastewater continuously without any sample pre-treatment. By the use of this instrument numerous possibilities arise, in order to control the sewers discharge load depend.
The contribution of thermophilic anaerobic digestion to the stable operation of wastewater sludge treatment
Authors: Zábranská J. , Dohányos M. , Jeníček P. , Zaplatílková P. , Kutil J.
Published: May 2018

Thermophilic anaerobic digestion of sewage sludge has been successfully operated in full-scale tanks almost three years. The higher loading capacity and specific biogas production rate in comparison with mesophilic digestion was proved. Thermophilic anaerobic sludge is also more resistant against foaming problems. Biogas from thermophilic tanks contains less hydrogen sulphide and other malodorous substances. Pathogens removal rate is apparently more efficient in the thermophilic process.
Project CARE: reducing wet weather overflows to improve beach water quality
Authors: Heijs J. , Wilkinson D. , Couriel E.
Published: May 2018

The people who live in North Shore City (New Zealand) consider the beaches as their greatest asset. Following public outcry on frequent beach pollution caused by wet weather sewer overflows, Project CARE commenced in 1998 to plan the improvements to the city's separated wastewater and stormwater systems to protect the streams and beaches, particularly from a public health perspective. The investigation included building hydrological and hydraulic models to represent the wastewater and stormwater systems and a receiving waters model to simulate the impacts on the beaches. These models were later used to explore options for improvement.

It was found that North Shore City has a very leaky wastewater system that is under capacity. The resulting wet weather overflows (12 per year on average) are the most important contributor to the problem although stormwater pollution alone is big enough to cause problems (at a smaller magnitude). A cost optimisation model (iterative process using performance/cost relationships) was then used to assist in identifying the optimal set of improvement works (storage, repair and increased capacity, wastewater treatment plant) to meet different performance targets and to cater for growth up to the year 2050. Cost Benefit analyses, looking at improvements in system performance and water quality, show diminishing returns for performance levels better than 2 overflows per year. The total costs that meet this target are estimated at almost NZ$300M (US$135M).
2D simulation of transport and degradation in the River Rhine
Authors: Teichmann L. , Reuschenbach P. , Müller B. , Horn H.
Published: May 2018

A simple 2D model has been developed for the simulation of mass transport and degradation of substances in the river Rhine. The model describes mass transport in the flow direction with a convective and a dispersive term. Transversal transport is described by segmenting the river and formulating a transversal exchange coefficient between the segments. Degradation can be formulated with any kinetics from first order to complex enzyme kinetics. The model was verified with monitoring data from the river Rhine. The hydrodynamic parameters such as dispersion coefficients and exchange coefficients were fitted to the conductivity, which was assumed to be non-degradable. The degradation term was fitted to ammonia values. The model was used to simulate measured concentrations of a readily (Aniline) and a poorly biodegradable substance (1,4-Dioxan) 10 m from the left river bank.

It was the objective of this research program to develop a model which allows a realistic estimation of the locally and regionally predicted environmental concentration of chemical substances in the EU risk assessment scheme.
Incorporating long-term trends in water availability in water supply planning
Authors: Luketina D. , Bender M.
Published: May 2018

This paper examines factors affecting water availability and hydrological trends of water supply. The relative impacts of the different factors have been assessed on a planning time frame of around 30 years. It is demonstrated that the non-greenhouse processes of multi-decadal climate change and el Niño-la Niña climate change will almost certainly be more significant than greenhouse induced climate change. Further, in developing countries, increased water consumption, population growth, and urbanization are likely to be the dominant factors when considering water availability. The type of responses that a water supply organization can make are discussed.
Distributed optimal technology networks: a concept and strategy for potable water sustainability
Authors: Weber W.J.
Published: May 2018

Viable strategies for ensuring adequate supplies of potable water are essential to long-term societal sustainability. The steadily increasing necessity for multiple reuse of water in urban societies is even now taxing our technical and financial abilities to meet ongoing needs for water suitable for human consumption. As a consequence, the current practice of treating the entire water demands of urban communities to the increasingly stringent standards required for drinking water is becoming an unsustainable practice, and thus a questionable strategy for planning and development of urban water systems. An innovative technology-based concept for implementation of a more sustainable strategy and practice for potable water is developed here. The concept is predicated on the inherent advantages of flexibility and responsiveness associated with decentralization of complex functions and operations. Specifically, it calls for strategic dispersal of flexible advanced treatment and control technologies throughout urban water transport and storage networks. This is in direct contradistinction to current strategies and practices of centralized and inflexible monolithic facilities. By integrating use-related satellite systems with critical components of existing systems and infrastructures, the concept can enable and facilitate optimal cost-effective applications of highly sophisticated advanced treatment and on-line monitoring and control technologies to in-place infrastructures in a holistic and sustainable manner.
Application of short-term water demand prediction model to Seoul
Authors: Joo C.N. , Koo J.Y. , Yu M.J.
Published: May 2018

To predict daily water demand for Seoul, Korea, the artificial neural network (ANN) was used. For the cross correlation, the factors affecting water demand such as maximum temperature, humidity, and wind speed as natural factors, holidays as a social factor and daily demand 1 day before were used. From the results of learning using various hidden layers and units in order to establish the structure of optimal ANN, the case of 3 hidden layers and numbers of unit with the same number of input factors showed the best result and, therefore, it was applied to seasonal water demand prediction. The performance of ANN was compared with a multiple regression method. We discuss the representation ability of the model building process and the applicability of the ANN approach for the daily water demand prediction. ANN provided reasonable results for time series prediction.
Linking expert evaluations with public consultation to design water policy at the watershed level
Authors: Garin P. , Rinaudo J.-D. , Ruhlmann J.
Published: May 2018

In view of the increasing demand for public participation in public affairs, the European Water Framework Directive requires public consultation when drawing up watershed management plans. Implementation of this Directive requires the development of methods for linking the scientific and technical knowledge of experts with the viewpoints expressed by local actors. The objective of this paper is to propose a public consultation method that can be used as early as the preliminary assessment of river basin characteristics, defined by the Directive, and at the scale of sub-watersheds that make up the district. A case study of a watershed in southern France illustrates this method.
Industrial wastewater minimization using water pinch analysis: a case study on an old textile plant
Authors: Ujang Z. , Wong C.L. , Manan Z.A.
Published: May 2018

Industrial wastewater minimization can be conducted using four main strategies: (i) reuse; (ii) regeneration-reuse; (iii) regeneration-recycling; and (iv) process changes. This study is concerned with (i) and (ii) to investigate the most suitable approach to wastewater minimization for an old textile industry plant. A systematic water networks design using water pinch analysis (WPA) was developed to minimize the water usage and wastewater generation for the textile plant. COD was chosen as the main parameter. An integrated design method has been applied, which brings the engineering insight using WPA that can determine the minimum flowrate of the water usage and then minimize the water consumption and wastewater generation as well. The overall result of this study shows that WPA has been effectively applied using both reuse and regeneration-reuse strategies for the old textile industry plant, and reduced the operating cost by 16% and 50% respectively.
Community analysis of nitrifying bacteria in an advanced and compact Gappei-Johkasou by FISH and PCR-DGGE
Authors: Ebie Y. , Matsumura M. , Noda N. , Tsuneda S. , Hirata A. , Inamori Y.
Published: May 2018

Fluorescent in situ hybridization (FISH) method with 16S rRNA-targeted oligonucleotide probes was used for quantitative estimation of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) in a Johkasou. Although the occupation ratios of AOB and NOB increased as nitrification progressed, about one month later, the occupation ratios decreased, despite showing good nitrification ability. Furthermore, even when urea was added to the feeding wastewater to raise the amount of T-N, the occupation ratios of both nitrifying bacteria remained constant. For further investigation, denaturing gradient gel electrophoresis (DGGE) was used to study the community structure of AOB in the Johkasou. As a result, DGGE band patterns and following sequence analysis revealed that the community structure of AOB was complicated and changed during this experiment. It was suggested that even if the occupation ratio of AOB to eubacteria was constant, the majorities of AOB were changed through temperature and load fluctuation. The combination of FISH and PCR-DGGE provides new information that was not available by conventional cultivationbased methods.
Reduction of sludge by ozone treatment and production of carbon source for denitrification
Authors: Ahn K.-H. , Yeom I.-T. , Park K.-Y. , Maeng S.-K. , Lee Y. , Song K.-G. , Hwang J.-H.
Published: May 2018

The feasibility of ozone treatment of municipal sludge for sludge reduction and carbon source production has been investigated. Significant accumulation of solubilized organics and unsettlable micro-solids (UMS) was observed at relatively low ozone dosages while mineralization became dominant at higher dosages. Batch denitrification experiments showed that the solubilized organics and the UMS could be utilized as carbon sources for nitrogen removal. In terms of overall sludge reduction, 54% reduction of the total sludge mass could be achieved by ozone treatment at 0.2 g-O3/g-MLSS.
Design parameters of high rate algal ponds using filamentous algae matrix for treating rural stream water
Authors: Kim T.E. , Chung W.M. , Lim B.S.
Published: May 2018

High rate algal ponds (HRAP) with a filamentous algae matrix (FAM) as the predominant species, were operated to evaluate the characteristics of FAM and the basic design parameters for treating polluted rural stream water. The porous and gelatinous FAM was formed like a sponge, which functions to prevent excessive loss of the algae in the effluent and can easily be retrieved from the ponds. The organic fraction of harvested FAM was about 88%, which is suitable for use as fertilizer. The HRAP system using FAM was found to be an effective nutrient removal process not requiring any artificial carbon sources for nitrification. At HRT 4 days, the T-N and T-P removal efficiencies were 85.9% and 65.8%, respectively. When the pH and water temperature were maintained above 9 and 15°C, HRT required for achieving a 70% T-N removal efficiency could be reduced by about 3 days. The oxygen production rate by FAM was calculated as 1.45 mgO2/L/m2. The design surface area of HRAP needed per rural inhabitant was about 2.72 m2.
Degradation of microcystin by biofilm in practical treatment facility
Authors: Saitou T. , Sugiura N. , Itayama T. , Inamori Y. , Matsumura M.
Published: May 2018

Potential for degradation of microcystin by biofilm was examined by some batch experiments using biofilm scraped from practical biological treatment facility combined with conventional treatment processes. The viable cells of Microcystis viridis, which produced microcystin LR, RR and YR were degraded at 6 to 10 days by the addition of biofilm. Biofilm collected in summer season had especially higher potential for degradation of Microcystis with complete degradation at 6 days. In all seasons, Monas spp. grew remarkably, accompanied with the higher decrease of the viable cells of Microcystis and the micro-animals were considered as a main predator for Microcystis cells. Intracellular microcystin LR, RR, YR were degraded simultaneously with high reduction of Microcystis cells. Dissolved microcystin LR of 1,000 μg l−1 was effectively degraded by indigenous aquatic bacteria on biofilm during 5 days, the degradability became higher with the increase in the concentration of microcystin LR. From the results of our research, it was clarified that the aggregated microorganisms consisting of biofilm had high potential for degradation of intracellular and dissolved microcystin.
Toxicity assessment of 255 chemicals to pure cultured nitrifying bacteria using biosensor
Authors: Tanaka Y. , Taguchi K. , Utsumi H.
Published: May 2018

The bioassay has been attracting attention as a method of toxicity assessments of micropollutants in the environment. In this study, we report the characteristics (selectivity and sensitivity) of the nitrifying bacteria biosensor for 255 kinds of chemicals as a model of chemical contaminant in the environment and the results of evaluation of mixed samples of several substances. In the nitrifying bacteria respiration inhibition test using the biosensor, 56 chemicals were detected. It was found that this biosensor is especially sensitive to seven chemicals that have a thiocarbonyl functional group (>C=S), such as a thioamide group of thiocarbamate group. These chemicals are considered to specifically inhibit AMO by chelation of copper. The samples consisted of a mixture of seven types of anilines that inhibit respiration in the bacteria, a mixture of five types of chlorophenols, and a mixture of eight types of substances that contain thiocarbonyl groups were examined. All of the mixed samples inhibited the respiration of the nitrifying bacteria more than 10% by the inhibition rate, and observed a synergistic effects of the substances in the samples.
Comparison of yeast-based estrogen receptor assays
Authors: Saito M. , Tanaka H. , Takahashi A. , Yakou Y.
Published: May 2018

In order to quantitatively compare measurement methods used to evaluate estrogenic activity in environmental samples, 13 substances and sewage samples were measured using three methods that employ recombinant yeast to measure such estrogenic activity. The estrogenic activity of the chemical substances confirmed a correlation between the three measurement methods. Two methods failed to measure estrogenic activity in some of the sewage samples because the yeast growth was inhibited. But the one remaining method was able to estimate the estrogenic activities of all sewage samples without the inhibition of the yeast growth. Similar correlation was observed between the methods for the estrogenic activities of the final discharge that was measured.
Nutrients in urine: energetic aspects of removal and recovery
Authors: Maurer M. , Schwegler P. , Larsen T.A.
Published: May 2018

The analysis of different removal and recovery techniques for nutrients in urine shows that in many cases recovery is energetically more efficient than removal and new-production from natural resources. Considering only the running electricity and fossil energy requirements for the traditional way of wastewater treatment and fertiliser production, the following specific energy requirements can be calculated: 45 MJ kg-1N for denitrification in a WWTP, 49 MJ kg-1P for P-precipitation in a WWTP, 45 MJ kg-1N for N-fertiliser and 29 MJ kg-1P for P-fertiliser production. These numbers are higher than the values derived for thermal volume reduction of urine (35 MJ kg-1N for eliminating 90% water) or production of struvite (102 MJ kg-1N, including 2.2 kg P). Considering only the electricity and fossil energy for the traditional way of wastewater treatment and fertiliser production, the energy value of 1 PE urine is 0.87 MJ PE-1d-1 (fertiliser value: 0.44, wastewater treatment: 0.43 MJ PE-1d-1).

A more detailed life cycle assessment (LCA) of the entire urine collection system, including the required materials and the environmental burden, support the energy analysis. The LCA compares conventional denitrification in a wastewater treatment plant with collecting urine in households, reducing the volume by evaporation and using it as a multi-nutrient fertiliser. The primary energy consumption for recovery and reuse of urine, including the nutrients N, P and K, is calculated with 65 MJ kg-1N, compared with 153 MJ kg-1N derived for the conventional 'recycling over the atmosphere'.
Wastewater reuse in on-site wastewater treatment: bacteria and virus movement in unsaturated flow through sand filter
Authors: Sélas B. , Lakel A. , Andres Y. , Le Cloirec P.
Published: May 2018

In on-site wastewater treatment plants, effluents are pre-treated by septic tank and treated by soil infiltration or sand filtration systems, with unsaturated flow conditions. These systems remove efficiently carbon, nitrogen and suspended solids. But for microbial pollution, the treatment efficiency depends on the hydrodynamic behaviour and filtering media characteristics. Contamination of superficial water and groundwater due to pathogenic viruses and pathogenic bacteria is responsible for many diseases. The objective of this study is to approach the mechanisms and operating conditions to control bacteria and virus release in the environment. Experiments were carried out on reactors of different length packed with sand. Hydraulic load of 90 cm.d−1 with a pulse periodic flow was used. The influence of chemical composition of the solution on the treatment efficiency has also been studied. For the first time, the residence time distribution (RTD) has been studied using a conservative tracer (KI), to determine the main hydrodynamic parameters. For the second time, the RTD with bacterial and viral tracers (E. coli, bacteriophage MS2) was applied, with the aim to define microbial behaviour in filtering media, including adsorption and filtration phenomena. This work allowed us to determine retardation factors according to the hydraulic loads and chemical composition.
Characteristics of coagulation-flocculation of humic acid with effective performance of polymeric flocculant and inorganic coagulant
Authors: Yu J. , Sun D.D. , Tay J.H.
Published: May 2018

Ferric chloride and aluminium sulphate as coagulants and positive charged flocculants PDDMAC ((PDDMAC = poly (diallyldimethylammonium chloride) were used for pre-treatment of water and wastewater for removing humic substance prior to RO membrane filtration. It was found that a combination of flocculant and coagulant enhanced the coagulation-flocculation process and humic acid removal. The optimum conditions of coagulation-flocculation were established in reference to the ratio of humic acid and coagulant. Zeta potential and the ratio of E4/E6 were investigated to explore the possible micro-mechanisms of coagulation-flocculation. The ratios of E4/E6 show the molecular size variations using different coagulants and flocculants, which are expected to benefit membrane-fouling control.
Nitrifying microbial community analysis of nitrite accumulating biofilm reactor by fluorescence in situ hybridization
Authors: Han D.W. , Chang J.S. , Kim D.J.
Published: May 2018

Biological nitrogen removal via nitrite pathway in wastewater treatment is very important especially in the cost of aeration and as an electron donor for denitrification. Wastewater nitrification and nitrite accumulations were carried out in a biofilm reactor. The biofilm reactor showed almost complete nitrification and most of the oxidized ammonium was present as nitrite at the ammonium load of 1.2 kg N/m3/d. Nitrite accumulation was achieved by the selective inhibition of nitrite oxidizers by free ammonia and oxygen limitation. Nitrite oxidation activity was recovered as soon as the inhibition factor was removed. Fluorescence in situ hybridization studies of the nitrite accumulating biofilm system have shown that genus Nitrosomonas which is specifically hybridized with probe NSM156 was the dominant nitrifying bacteria while Nitrospira was less abundant than those of normal nitrification systems. Further FISH analysis showed that the combinations of Nitrosomonas and Nitrospira cells were identified as important populations of nitrifying bacteria in an autotrophic nitrifying biofilm system.
A submerged tubular ceramic membrane bioreactor for high strength wastewater treatment
Authors: Sun D.D. , Zeng J.L. , Tay J.H.
Published: May 2018

A 4 L submerged tubular ceramic membrane bioreactor (MBR) was applied in laboratory scale to treat 2,400 mg-COD/L high strength wastewater. A prolonged sludge retention time (SRT) of 200 day, in contrast to the conventional SRT of 5 to 15 days, was explored in this study, aiming to reduce substantially the amount of disposed sludge. The MBR system was operated for a period of 142 days in four runs, differentiated by specific oxygen utilization rate (SOUR) and hydraulic retention time (HRT). It was found that the MBR system produced more than 99% of suspended solid reduction. Mixed liquor suspended solids (MLSS) was found to be adversely proportional to HRT, and in general higher than the value from a conventional wastewater treatment plant. A chemical oxygen demand (COD) removal efficiency was achieved as high as 98% in Run 1, when SOUR was in the range of 100-200 mg-O/g-MLVSS/hr. Unexpectedly, the COD removal efficiency in Run 2 to 4 was higher than 92%, on average, where higher HRT and abnormally low SOUR of 20-30 mg-O/g-MLVSS/hr prevailed. It was noted that the ceramic membrane presented a significant soluble nutrient rejection when the microbial metabolism of biological treatment broke down.