bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure and function of nitrifying biofilms as determined by molecular techniques and the use of microelectrodes
Authors: Okabe S. , Naitoh H. , Satoh H. , Watanabe Y.
Published: May 2018

The phylogenetic diversity of a nitrifying bacterial community of two types of nitrifying biofilms, a domestic wastewater biofilm and an autotrophic nitrifying biofilm grown on rotating disk reactors (RDR), was characterized by 16S ribosomal DNA (rDNA)-cloning analysis. Thereafter, successional development of nitrifying the bacterial community within both biofilms was visualized in situ by fluorescent in situ hybridization (FISH) with a set of fluorescently labeled 16S rRNA-targeted DNA probes. In situ hybridization revealed that Nitrosomonas ureae was the numerically dominant species of the ammonia-oxidizing population in the domestic wastewater biofilm and that a population shift from N. urea to N. europaea and N. eutropha occurred when the culture medium was switched to the synthetic media from the domestic wastewater. After reaching the steady-state condition, microprofiles of NH4+, NO2−, NO3−, and O2 in the biofilms were measured by use of microsensors, and the spatial distributions of in situ nitrifying activities were determined. The relationship between the spatial organization of nitrifying bacterial populations and the in situ activity of these populations within the biofilms was discussed. Microelectrode measurements revealed that the active ammonia-oxidizing zone was vertically separated from the active nitrite-oxidizing zone. This vertical separation became more evident with increase of the substrate C/N ratio, leading to deterioration of nitrification efficiency. The combined use of these techniques made it possible to relate in situ nitrifying activity directly to the occurrence of nitrifying bacterial populations.
Molecular analysis of ammonia-oxidizing bacterial populations in aerated-anoxic Orbal processes
Authors: Park H.-D. , Regan J.M. , Noguera D.R.
Published: May 2018

Aerated-anoxic processes operate under the principle that small additions of oxygen to an anoxic reactor induce simultaneous nitrification and denitrification. In these systems, ammonia oxidation in the anoxic zone can easily account for 30–50% of the total nitrification in the reactor, even though the dissolved oxygen concentration is usually below detection limit. To investigate whether the nitrification efficiency in aerated-anoxic processes was due to the presence of specialized ammonia-oxidizing bacteria (AOB), an analysis of the AOB population in an aerated-anoxic Orbal process and a conventional nitrogen removal process was carried out using phylogenetic analyses based on the ammonia monooxygenase A (amoA) gene. Terminal restriction fragment length polymorphism (TRFLP) analyses revealed that Nitrosospira-like organisms were one of the major contributors to ammonia oxidation in a full-scale aerated-anoxic Orbal reactor. However, the relative populations of Nitrosospira-like and Nitrosomonas-like AOB were not constant and appeared to have seasonal variability. Cloning and sequence comparison of amoA gene fragments demonstrated that most of the AOB in the aerated-anoxic Orbal process belonged to the Nitrosospira sp. and Nitrosomonas oligotropha lineages. The abundance of Nitrosospira-like organisms in aerated-anoxic reactors is significant, since this group of AOB has not been usually associated with nitrification in wastewater treatment plants.
A comparison of autotrophic ammonia-oxidizing bacteria in full- and laboratory-scale wastewater treatment reactors
Authors: Rowan A.K. , Snape J.R. , Fearnside D. , Curtis T.P. , Barer M.R. , Head I.M.
Published: May 2018

Lab-scale reactors are commonly used to simulate full-scale plants as they permit the effects of defined experimental perturbations to be evaluated. Ideally, lab- and full-scale reactors should possess similar microbial populations. To determine this we compared the diversity of the β-proteobacterial autotrophic ammonia-oxidising bacteria (AOB) in a full-scale and lab-scale biological aerated filter (BAF) using PCR with AOB selective primers combined with denaturing gradient gel electrophoresis (DGGE). PCR amplified 16S rRNA gene fragments from the nitrification unit of the lab-and full-scale BAF were subjected to cloning and sequencing to determine the phylogenetic affiliation of the AOB. A high degree of comparability between the lab-and full-scale BAF was observed with respect to AOB populations. However minor differences were apparent. The importance of these minor constituents in the overall performance of the reactor is unknown. Nonetheless the lab-scale reactor in this study did appear to reflect the dominant AOB community within the full-scale equivalent.
Gas chromatographic analysis of polyhydroxybutyrate in activated sludge: a round-robin test
Authors: Baetens D. , Aurola A.-M. , Foglia A. , Dionisi D. , van Loosdrecht M.C.M.
Published: May 2018

Polyhydroxyalkanoates (PHA) and poly-β-hydroxybutyrate (PHB) in particular have become compounds which is routinely investigated in wastewater research. The PHB analysis method has only recently been applied to activated sludge samples where PHA contents might be relatively low. This urges the need to investigate the reproducibility of the gas chromatographic method for PHB analysis. This was evaluated in a Round-Robin test in 5 European laboratories with samples from lab-scale and full-scale enhanced biological phosphorus removal systems. It was shown that the standard deviation of measurements in each lab and the reproducibility between the labs was very good. Experimental results obtained by different laboratories using this analysis method can be compared. Sludge samples with PHB contents varying between 0.3 and 22.5 mg PHB/mg sludge were analysed. The gas chromatographic method allows for PHV, PH2MB and PH2MV analysis as well.
On the development of a novel image analysis technique to distinguish between flocs and filaments in activated sludge images
Authors: Cenens C. , Van Beurden K.P. , Jenné R. , Van Impe J.F.
Published: May 2018

The ratio of flocs to filaments in activated sludge wastewater treatment plants is of extreme importance for the overall performance of the plant. In order to control this ratio the individual concentrations of flocs and filaments need to be measurable. However, no sensors which can measure these concentrations are currently available. In this paper it is outlined how a distinction can be made between flocs and filaments by means of image analysis techniques. Combination of this information with the total biomass concentration results in the individual floc and filament concentrations. The distinction of objects of interest from the background is a crucial step in the image analysis procedure. An automatic thresholding algorithm is proposed which selects two thresholds in images with one fraction darker than the background and the other fraction brighter than the background. Once the objects are separated from the background, they are classified as either flocs or filaments by means of the reduced radius of gyration.
Active heterotrophic and autotrophic biomass distribution between fixed and suspended systems in a hybrid biological reactor
Authors: Ochoa J.C. , Colprim J. , Palacios B. , Paul E. , Chatellier P.
Published: May 2018

This paper presents the results obtained when modifying sludge retention time (SRT 8, 5, and 3.7 days during phases A, B and C respectively) for a hybrid biological reactor (HR) compared with a classical activated sludge process. The study was conducted by following active biomass evolution and distribution for two lab-scale pilots plants operating with the same conditions, one acting as HR and the other as the control reactor (CR) without support material. At the end of phase C, support material was split into two fractions between both reactors to study the effect of support to reactor volume ratio (Fr). Active biomasses in suspended and fixed systems were calculated using respirometric techniques. Evolutions of active autotrophic and heterotrophic biomasses for both reactors are presented during all the operational periods and it is observed that in the HR biomass concentrations are up to double that in the CR, mainly due to the presence of support material. When studying biomass distribution in HR, autotrophic biomass is mainly located over the support material (from 95% to 99% during periods A and C respectively) while only about 60% of heterotrophic biomass is located over the support.
A comparison among different methods for evaluating the biomass activity in activated sludge systems: preliminary results
Authors: Andreottola G. , Baldassarre L. , Collivignarelli C. , Pedrazzani R. , Principi P. , Sorlini C. , Ziglio G.
Published: May 2018

In order to improve activated sludge plant operation (achieving higher efficiency and cost savings) beside influent and effluent characteristics and working parameters (e.g. dissolved oxygen, total and volatile suspended solids, pH, recirculation flow rate, etc.), the biomass activity should be monitored, the bacteria being responsible for the pollutant degradation. Since conventional cultivation based methods are inadequate to quantify environmental microorganisms (due to scarce number of cultivable microorganisms and time-consuming procedures) several “non-conventional” techniques were applied in this study, in order to compare the obtainable information and their routine feasibility. Different measurements (VSS concentration, Oxygen Uptake Rate, microbial counts by cultural and biomolecular methods – MPN-PCR, ATP content, dehydrogenase activity, microbial cell viability and enzymatic activity) were carried out on mixed liquor samples, taken from a municipal activated sludge plant (440,000 p. e.). The preliminary results of the research are presented in this paper.
Decay rate variability of active heterotrophic biomass
Authors: Lavallée B. , Lessard P. , Besser C.
Published: May 2018

Hypotheses of the ASM1 model state that the specific respiration rate of heterotrophic active biomass is a constant. It thus becomes possible to assess the active heterotrophic biomass decay rate (bH) during starvation. The object of this study is to verify if the specific respiration rate of heterotrophic biomass remains constant throughout starvation, and if it is typical of global metabolic biomass activity, as proposed by the model hypotheses. The decay rate bH was evaluated using respirometric and enzymatic measurements. Measurement of bH through respirometry on various sludges varied between 0.28 and 0.76 d−1. According to the enzyme and respirometric measurements carried out, a large portion of this value is related to enzymatic regulation. During starvation, when initial active biomass activity is high, down regulation of the respiratory chain results in a decrease in the specific heterotrophic active biomass respiration rate, thus creating an overevaluation of the decay rate as measured by respirometry. Thus a high decay rate used in the ASM1 model could eventually lead to a poor forecast of biomass production.
Fighting foam with phages?
Authors: Thomas J.A. , Soddell J.A. , Kurtböke D.I.
Published: May 2018

Seventeen (17) phages infective for the mycolata were isolated from six samples of activated sludge using 21 prospective hosts from the genera Dietzia, Gordonia, Nocardia, Rhodococcus, Tsukamurella and Mycobacterium. Their morphology indicated that they were all members of the viral family Siphoviridae, but they varied in the size of the icosahedral head and length of non-contractile tail, suggesting they were different. This was confirmed by host-range studies with 47 strains of mycolata, which showed that each phage had a unique host-range, and this was polyvalent in the majority (15/17) of cases, with 12 phages infective for hosts representing two or three of the genera Gordonia, Nocardia and Rhodococcus. The potential for use of these phages in the control of foaming and other applications is discussed.
An investigation into studying of the activated sludge foaming potential by using physicochemical parameters
Authors: Hladikova K. , Ruzickova I. , Klucova P. , Wanner J.
Published: May 2018

This paper examines how the physicochemical characteristics of the solids are related to foam formation and describes how the foaming potential of full-scale plants can be assessed. The relations among activated sludge and biological foam hydrophobicity, scum index, aeration tank cover and filamentous population are evaluated. Individual parameter comparison reveals the scumming intensity can be estimated only on the assumption that foams is already established. None of the above mentioned characteristics can be reliably used to predict the foaming episodes at wastewater treatment plants.
Cascade control strategy for external carbon dosage in predenitrifying process
Authors: Cho J.-H. , Sung S.W. , Lee I.-B.
Published: May 2018

We propose a cascade control strategy composed of two Proportional-Integral (PI) controllers to regulate the nitrate concentration in the predenitrifying process by manipulating the external carbon dosage. It controls the nitrate concentrations in the effluent as well as in the final anoxic reactor simultaneously to strictly satisfy the quality of the effluent as well as to remove the effects of disturbances more quickly. The design of two PI controllers in the cascade control loop can be completed with the Ziegler–Nichols (Z–N) tuning rule together with a simple relay feedback identification method. Results from the Benchmark simulation confirm that both good set point tracking and satisfactory disturbance rejection can be guaranteed due to the structural advantages of the proposed cascade control strategy. Also, compared with a previous work, the fluctuation of the nitrate concentration in the effluent has been decreased significantly.
Pilot-scale testing membrane bioreactor for wastewater reclamation in industrial laundry
Authors: Andersen M. , Kristensen G.H. , Brynjolf M. , Grüttner H.
Published: May 2018

A pilot-scale study of membrane bioreactor treatment for reclamation of wastewater from Berendsen Textile Service industrial laundry in Søborg, Denmark was carried out over a 4 month period. A satisfactory COD degradation was performed resulting in a low COD in the permeate (<50 mg/l). To obtain satisfactory treatment, addition of nitrogen was necessary. The biodegradability of the permeate was very low (BOD5<2 mg/l). A hydraulic retention time of 1 d turned out to be sufficient at a sludge concentration of 10 g MLSS/l. Through addition of a cationic polymer, a satisfactory dewaterability of the sludge was reached. Membrane tests showed that operating at a trans-membrane pressure of 3 bar and a cross-flow velocity of 4 m/s, a flux of 120 l/m2h can be expected without using chemicals for membrane cleaning. The quality of the permeate was very good when comparing to the reuse quality demands of water to the wash processes. Reuse of the permeate in all rinsing steps requires additional treatment through reverse osmosis.
Evaluation of different shape parameters to distinguish between flocs and filaments in activated sludge images
Authors: Benens C. , Jenné R. , Van Impe J.F.
Published: May 2018

The ratio of flocs to filaments in activated sludge waste water treatment plants is of extreme importance for the overall performance of the plant. In order to control this ratio the individual concentrations of flocs and filaments need to be measurable. However, no sensors which can measure these concentrations are currently available. It is proposed that by means of image analysis techniques the ratio of flocs to filaments can be determined. Combination of this ratio with the total biomass concentration results in the individual floc and filament concentration. This contribution focuses on the last step of the image analysis procedure, i.e., the classification of objects as either floc or filament. Five different shape parameters, i.e., aspect ratio, roundness, form factor, fractal dimension and reduced radius of gyration, are evaluated and compared. The results indicate that the form factor is the least suitable and the reduced radius of gyration the most suitable shape parameter to accurately classify flocs and filaments in activated sludge images.
Soft sensors for control of nitrogen and phosphorus removal from wastewaters by neural networks
Authors: Luccarini L. , Porrà E. , Spagni A. , Ratini P. , Grilli S. , Longhi S. , Bortone G.
Published: May 2018

In this paper, we describe the results of research aimed to evaluate the possibility of using a neural network (NN) model for predicting biological nitrogen and phosphorus removal processes in activated sludge, utilising oxidation reduction potential (ORP) and pH as NN inputs. Based on N and P concentrations predictions obtained via the NN, a strategy for controlling sequencing batch reactors (SBRs) phases duration, optimising pollutants removal and saving energy, is proposed. The NN model allowed us to reproduce the concentration trends (change in slope, or process end), with satisfactory accuracy. The NN results were generally in good agreement with the experimental data. These results demonstrated that NN models can be used as “soft on-line sensors” for controlling biological processes in SBRs. By monitoring ORP and pH, it is possible to recognise the N and P concentrations during different SBRs phases and, consequently, to identify the end of the biological nutrient removal processes. This information can then be used to design control systems.
An efficient monitoring concept with control charts for on-line sensors
Authors: Thomann M. , Rieger L. , Frommhold S. , Siegrist H. , Gujer W.
Published: May 2018

A monitoring concept for on-line sensors will be discussed which helps the WWTP staff to detect drift-, shift- and outlier effects as well as unsatisfactory calibration curves. The approach is based on the analysis of comparative measurements between the sensor and a reference method. It combines statistical analysis such as control charts and regression analysis with decision support rules. The combination of two different detection levels in the selected Shewhart control charts with additional criteria allows one to detect ‘out-of-control’ situations early with an optimized measurement effort. Beside the statistical analysis the concept supports the operator with a graphical analysis to monitor the accuracy of on-line measurements efficiently. The widely applicable monitoring concept will be illustrated with examples for an ion-sensitive NH4+- and a MLSS-sensor.
Early warning-system for operation-failures in biological stages of WWTPs by on-line image analysis
Authors: Heine W. , Sekoulov I. , Burkhardt H. , Bergen L. , Behrendt J.
Published: May 2018

By the observation and evaluation of the microscopic picture of activated sludge samples it is possible to introduce another biological parameter additional to conventional physico-chemical parameters for the control of biological stages of waste water treatment plants. Considering the fact that parameters like floc size and floc size distribution, structure of the flocs (compact/open), shape of the flocs (round/irregular) allow perceptions of the adjusted operation conditions of the biological stages, evidence for changing operation conditions or threatening operation disturbances can be recognised. This recognition takes place at a very early phase, because the morphology of activated sludge flocs reacts very fast to changing conditions. An automatic image analysis of activated sludge floc pictures would enable the introduction of a new sum parameter to enhance operation control of aeration tanks. By a statistical evaluation of the processed sludge images several parameters can be used to describe the alteration of activated sludge flocs characteristics.

With these biological parameters it is possible to detect altered operation conditions or threatening or existing operation problems at an early phase. Thus it is possible to plan suitable countermeasures. Furthermore, the microscopic picture is the only parameter, that gives important information about the structure of the activated sludge flocs and the biozenosis. In comparison with the mainly used physico-chemical parameters, that just give information about the inlet and outlet of the wastewater treatment plants, the microscopic picture is the only parameter that gives information about the biology of the wastewater treatment process. By means of this biological parameter an improved control and regulation of the biological stages of wastewater treatment plants can be obtained.
Comparison of combined and separated biological aerated filter (BAF) performance for pre-denitrification/ nitrification of municipal wastewater
Authors: Rother E. , Cornel P. , Ante A. , Kleinert P. , Brambach R.
Published: May 2018

The performance of two systems of semi-industrial up-flow biological aerated filters (BAF) with pre-denitrification followed by nitrification was studied and compared under various operating and loading conditions. The first system consisted of two separate reactors for the denitrification and the nitrification step, whereas in the second system the aerobic nitrification zone was packed on top of the anoxic denitrification zone in one reactor. The second system potentially offers substantial savings in investment costs and space requirements for a large scale treatment plant.

Regarding the elimination of carbonaceous pollution and denitrification the systems did not show significant differences. However, nitrification in the combined system suffered from the mixing of different biocenosis by daily backwashing and was reduced to 50-70% of the separated system's performance. Factors such as oxygen concentration, raw water composition and loading rates affected both systems' nitrification rates in similar ways. Since it is impossible to optimise the nitrification and denitrification processes separately, the combined system should only be considered for large scale applications if space is very scarce and if a stable raw water composition can be expected. If strict limit values for nitrate have to be met in the effluent, a combination of pre- and post-denitrification is advantageous and advisable.
Balancing of nitrogen conversion in deammonifying biofilms through batch tests and GC/MS
Authors: Gaul T. , Filipov E. , Schlösser N. , Kunst S. , Helmer-Madhok C.
Published: May 2018

Growth carriers from a technical deammonifying moving-bed WWTP were used in batch tests to determine possible N-conversion reactions under varying oxygen and substrate conditions. Deammonification, denitrification, and nitrification reactions could be proved using conventional analysis, combined with gas chromatography/mass spectrometry analysis to get additional information about 15N-isotope labelled gaseous end products of the different reactions. In this orientating study N2O could be observed in some cases up to 12% of the total gas production. N2O production came from incomplete denitrification processes under anoxic or oxygen-limiting conditions and in the absence of organic substrate. It seems as if structural components of deammonifying biofilms play a crucial role for the portion of side-reactions, leading to undesirable gaseous end products.
Sensor system using polarization analysis method to monitor oil-on-water in water purification plants and rivers
Authors: Sanuki Y. , Hiraoka M. , Ohto T. , Kanai H. , Tada H.
Published: May 2018

Some 80% of accidental pollution in river water is caused by oil spills. Oil spills can cause serious damage such as suspension of water intake at water purification plants and major harm to ecosystems in the lower reaches of rivers. This is because oil-on-water tends to spread easily, quickly exacerbating the damage. To address this problem, an automated, continuous sensor system with high sensitivity can be used for early detection of spill accidents.

We have developed a sensor system for detecting oil-on-water based on a polarization analysis method. Its advantages include: a) no direct contact with sample water; b) minimal maintenance; c) largely unaffected by foreign matter and waves on the water surface; and d) much higher sensitivity than simple visual observation.

This paper describes the measurement principle and configuration of the sensor system, and discusses the results of sensitivity tests and tests on the influence of water turbidity, foreign matter and waves. We will also consider some of the limitations of the new system.
Detection of Escherichia coli in water by culture-based amperometric and luminometric methods
Authors: Nistor C. , Osvik A. , Davidsson R. , Rose A. , Wollenberger U. , Pfeiffer D. , Emnéus J. , Fiksdal L.
Published: May 2018

The application of amperometric biosensor- and chemiluminiscence based methods for rapid detection of viable E. coli in water has been investigated. An amplification of the amperometric signal by a factor of 4 was obtained when the cellobiose dehydrogenase (CDH) biosensor was used instead of a plain graphite electrode for detection of b-galactosidase (b-GAL) activity at 22.5°C. A linear correlation was demonstrated for detection time (DT) vs. initial concentrations (logarithmic units) of E. coli lT1 and E. coli in environmental samples, respectively, by use of the CDH biosensor or a chemiluminometric technique. The study has shown that an E. coli concentration ≥ 104 cfu/100 mL in environmental samples was determined by the CDH biosensor within one working day. However, further reduction of the DT can be obtained, e.g. by increasing the signal amplification factor using other biosensors.
Detecting odorous materials in water using quartz crystal microbalance sensors
Authors: Ogawa S. , Sugimoto I.
Published: May 2018

Water drawn from rivers into purification plants must be checked for the presence of odorous materials because oil or organic-solvent contamination of the water may occur. If the detection of odorous materials in water is untimely or fails, the consequences can be serious. Therefore, the water must be checked continuously. We have developed a water-monitoring system that uses a highly sensitive electronic nose consisting of quartz crystal microbalance sensors to detect odorous materials in water. The nose is sensitive enough to detect petroleum hydrocarbons without water vapor at a low-ppb level. However, the nose is very sensitive to humidity and temperature. We have thus developed a method for accurately maintaining the humidity and temperature in the sensor cell. Experimental results show that the developed system can quickly detect contaminated water that was mixed with gasoline, kerosene, or benzene (concentration: several hundred ppb level), and we should be able to classify the pollutant by using pattern recognition of the dynamic sensor response.
Comparison of aerobic and anoxic phosphorus uptake in ndbepr systems (uct and enbnras)
Authors: Vermande S.M. , Sötemann S. , Aguilera Soriano G. , Wentzel M. , Audic J.M. , Ekama G.
Published: May 2018

Two Nitrification-Denitrification Biological Excess Phosphorus Removal (NDBEPR) systems have been operated for 8.5 months in order to compare their Biological Excess Phosphorus Removal (BEPR) performance. One of these systems, i.e. the University of Cape Town (UCT) system, exhibits mainly aerobic P uptake while the External Nitrification Biological Nutrient Removal Activated Sludge (ENBNRAS) system is characterised by high anoxic P uptake. It was observed that when operating with predominantly aerobic P uptake, the UCT system released more P than the ENBNRAS system, even though it had a lower anaerobic mass fraction. However, when the influent TKN/COD was high, i.e. >0.1, anoxic P uptake also occurred in the UCT system and P release dropped to lower levels than in the ENBNRAS. Accordingly, P uptake of the UCT system was 5 mg P/l influent higher than that of the ENBNRAS system, when it was predominantly aerobic, but 9 mg P/l influent lower when anoxic P uptake occurred. As a result, the UCT system achieved superior P removal when aerobic P uptake was predominant (23% higher), but when high influent TKN/COD promoted anoxic P uptake the P removal of the UCT system was poorer than that of the ENBNRAS system. This study clearly showed that anoxic P uptake is not beneficial to NDBEPR systems.
Start-up of a pilot-scale anaerobic fixed film reactor at low temperature treating slaughterhouse wastewater
Authors: del Pozo R. , Diez V. , Salazar G.
Published: May 2018

A pilot-scale anaerobic fixed film reactor (AFFR) with vertically arranged PVC tubes as biomass carrier, treating poultry slaughterhouse wastewater was started-up in 74 days at temperatures between 20-24°C. The start-up process consisted of a long acclimatization phase followed by a low loaded growth phase, a gradual increase of OLR up to 9.2 kg COD/m3d, and a final maturation phase at moderated loads of 2.7 kg COD/m3d at which total COD removal efficiencies of 57% were achieved. Alkalinity ratio IA:PA was found to be the best control parameter to avoid VFA accumulation. OLR increase based on pH control was not satisfactory because changes in CO2 solubility caused daily by temperature and flow variations led to pH oscillations of 0.2 units. The low wastewater alkalinity, 260 mg/l CaCO3, was insufficient to buffer the pH system, therefore the pH decrease associated with the VFA accumulation was not easily detected and could not be used as a way of OLR control. Organic matter removal took place by accumulation and biodegradation processes. Limitation in the reactor hydrodynamics and particulate fraction hydrolysis was detected at high flow rates.
Model based prediction of the clogging of an anaerobic fixed bed reactor
Authors: Harmand J. , Miens F. , Conte T. , Gras P. , Buffière P. , Steyer J.P.
Published: May 2018

This paper presents the use of nonlinear constrained optimization techniques in order to detect and evaluate the degree of clogging in an anaerobic fixed bed reactor. First, experimental results show that the validity of a mass balance model can degrade over the time. Using the available model of the process and nonlinear constrained optimization tools, it is established that these changes can be due to the decrease of the liquid volume into the reactor while the mean values of biomass concentrations increase, leading to the clogging of the reactor. These theoretical results are confirmed experimentally in evaluating the hydraulic retention time of the reactor using a tracer.
A method for automatic validation of long time series of data in urban hydrology
Authors: Mourad M. , Bertrand-Krajewski J.-L.
Published: May 2018

Modelling in urban hydrology is largely based on the analysis of long time series of data. The quality of the results strongly depends on the quality of the data used. Doubtful or wrong data must be detected and eventually substituted by reliable ones when it is feasible before any further exploitation. This paper deals with the development of an automatic pre-validation procedure that detects doubtful and not reliable data, in order to facilitate their interpretation. This procedure consists in applying a set of seven tests based on the following criteria : the functioning state of the sensor, the physical range of the quantity, the locally realistic range, the duration since the last maintenance of the sensor, the signal's gradient, material redundancy and analytical redundancy. The results of the tests are coded with the letter A for reliable values, B for doubtful values and C for wrong values. After this automatic prevalidation, the ultimate validation of values marked B and C is carried out manually by the operator, with the assistance of specifically developed visual and graphical tools.
Adsorption of estrone on nanofiltration and reverse osmosis membranes in water and wastewater treatment
Authors: Nghiem L.D. , Schäfer A.I. , Waite T.D.
Published: May 2018

Adsorption of the trace contaminant estrone, a natural hormone and commonly abundant in surface waters and in treated as well as untreated wastewaters, to eight commercial nanofiltration and reverse osmosis membranes was investigated under well defined conditions. Experiments were conducted in stainless steel stirred cells by spiking trace levels (100 ng.L−1) of estrone into five different matrices, namely MilliQ water, a bicarbonate solution, synthetic natural waters containing natural organics, and secondary effluent. Results show that estrone is adsorbed to the membranes to varying degrees with extent of adsorption influenced by the feedwater composition with different mechanisms of association controlling adsorption to different membrane types. Increase in membrane resistance is typically observed to result in decrease in extent of estrone adsorption.
Application of toxicity monitor using nitrifying bacteria biosensor to sewerage systems
Authors: Inui T. , Tanaka Y. , Okayasu Y. , Tanaka H.
Published: May 2018

Toxic substances may be included in wastewater influent and can damage biological processing of wastewater treatment, therefore continuous toxic-monitoring of wastewater influent is needed. This paper describes the potential toxic-monitoring applications of the toxicity monitor using a nitrifying bacteria biosensor to sewerage systems. The results of sensitivity tests show that aspects of wastewater do not affect the sensor sensitivity and confirm that the sensor can be applied to wastewater monitoring as it is. The monitor with a prototype of filtration system installed in a wastewater treatment plant is able to operate continuously for one month at least after the modification of filtration system and the optimization of operation conditions.
A hybrid supervisory system to support WWTP operation: implementation and validation
Authors: Rodriguez-Roda I.R. , Sànchez-Marrè M. , Comas J. , Baeza J. , Colprim J. , Lafuente J. , Cortes U. , Poch M.
Published: May 2018

Integrated operation of Wastewater Treatment Plants is still far from being solved. A reasonable proposal should link advanced and robust control algorithms to some knowledge-based techniques, allocating the detailed engineering to numerical computations, while delegating the logical analysis and reasoning to supervisory intelligent systems. This paper describes the development and implementation of a knowledge-based Hybrid Supervisory System to support the operation of a real Wastewater Treatment Plant. The system integrates different reasoning modules, overcoming the limitations in the use of each single technique, while providing an agent based architecture with additional modularity and independence. It is structured into three separated levels: data gathering, diagnosis, and decision support. The different tasks of the system are performed in a seven-step cycle: data gathering and update, diagnosis, supervision, prediction, communication, actuation, and evaluation phase. In spite of certain reservations of the scientific community about the use of these techniques, the system is successfully performing real-time support to the operation of the Granollers facility since September 1999. Results of the first four-month validation period are shown and discussed. An example of the system behavior is also shown in the paper. The conclusions indicate the key steps which are necessary to transfer the system to another facility.
Simulation study supporting wastewater treatment plant upgrading
Authors: Hvala N. , Vrečko D. , Burica O. , Strazžar M. , Levstek M.
Published: May 2018

The paper presents a study where upgrading of an existing wastewater treatment plant was supported by simulation. The aim of the work was to decide between two technologies to improve nitrogen removal: a conventional activated sludge process (ASP) and a moving bed biofilm reactor (MBBR). To perform simulations, the mathematical models of both processes were designed. The models were calibrated based on data from ASP and MBBR pilot plants operating in parallel on the existing plant. Only two kinetic parameters needed to be adjusted to represent the real plant behaviour. Steady-state analyses have shown a similar efficiency of both processes in relation to carbon removal, but improved performance of MBBR in relation to nitrogen removal. Better performance of MBBR can be expected especially at low temperatures. Simulations have not confirmed the expected less volume required for the MBBR process. Finally, the MBBR was chosen for plant upgrading. The developed process model will be further used to evaluate the final plant configuration and to optimise the plant operating parameters.
Co-removal of hexavalent chromium during copper precipitation
Authors: Sun J. , Huang J.-C.
Published: May 2018

In our recent study using the nucleated precipitation technology to treat plating wastewater, it was found that about one half of hexavalent chromium was co-removed with copper, nickel and zinc. Since hexavalent chromium could not react with either hydroxide or carbonate to from precipitates, this study was undertaken to evaluate the mechanism(s) involved in the chromium co-removal.

Batch tests were conducted with synthetic solutions containing either only copper or both copper and hexavalent chromium. Metal precipitation was induced by adding Na2CO3 to different pH, and the quantitative removal of copper and chromium was determined. Besides, the [Cr]/[Cu] molar ratio of produced precipitates were also assessed in conjunction with the EDAX analysis to determine their compositions. Experimental results indicate that for pure copper solution, precipitation begins at pH 6.0, and completes at pH 7.0. The chemical forms of the precipitates are copper carbonates [CuCO3.Cu(OH)2 and CuCO3.2Cu(OH)2]. On the other hand, in a bi-metal solution of copper plus chromium, precipitation of copper begins at about pH 5.0, and copper precipitation is always accompanied by some chromium removal. From the removal stoichiometry of the two metals, it is found that at low pH, the co-removal is a result of “co-precipitation” which results in the formation of CuCrO4 crystallites. Once such crystallites are formed, they provide a heterogeneous environment which enhances an early formation of copper carbonate at a lower pH (below 5.5). It is further found that once copper carbonate precipitates are produced, the remaining soluble will precipitate in such form, and at this stage further removal of copper is no longer accompanied by additional chromium removal. The test data also reflect that the produced copper carbonates are positively charged, as verified by zeta potential measurement, at pH below 7.5. Thus they are able to adsorb some anionic chromium (existing as chromate) through electrostatic attraction and/or inorganic ligand exchange. At pH of 6 to 10, the extent of adsorption decreases with increasing pH, and the adsorption capacity seems to coincide with the progressive reduction of positive zeta potentials of the precipitated particles.
Dynamic online sewer modelling in Helsingborg
Authors: Hernebring C. , Jönsson L.-E. , Thorén U.-B. , Møller A.
Published: May 2018

Within the last decade, the sewer system in Helsingborg, Sweden has been rehabilitated in many ways along with the reconstruction of the WWTP Öresundsverket in order to obtain a high degree of nitrogen and phosphorus removal. In that context a holistic view has been applied in order to optimise the corrective measures as seen from the effects in the receiving waters. A sewer catchment model has been used to evaluate several operation strategies and the effect of introducing RTC. Recently, a MOUSE ONLINE system was installed. In this phase the objective is to establish a stable communication with the SCADA system and to generate short-term flow forecasts.
Voluntary arrangements to cope with diffuse pollution from agriculture and their role in European water policy
Authors: Heinz I. , Andrews K. , Brouwer F. , Zabel T.
Published: May 2018

A limited number of Member States in the EU have gained experience with establishing co-operative agreements between agriculture and the water sector. Their main aim is to reduce or prevent water pollution caused by intensive farming practices. The research has shown that significant changes in farming practices have been achieved as a result of negotiation between farmers and water suppliers. Consequently, in many catchment areas improvements in water quality can be observed. Co-operative agreements have the important advantage that the measures taken can be tailored to the different local conditions in catchment areas. Reducing diffuse pollution resulting from intensive agriculture is one of the main issues of the EU Water Framework Directive. The current paper builds on the results of a EU-wide research project which examines the role co-operative agreements can play in water policy and the Common Agricultural Policy.
Sustainable development - assessment of water resource management measures
Authors: Weigert F.B. , Steinberg C.E.W.
Published: May 2018

An approach is presented which supports decision makers in the field of water resource management to create and evaluate alternative strategies in the context of goals based on in sustainable development. The broad range of water resource management activities demand a highly structured methodology. The building blocks of the assessment procedure range from the characterization of the status quo to the development and application of assessment aids to perform exemplary evaluations.
SIRRUS: evaluation software of the technical and economic profitability of rainwater on an industrial site
Authors: Thomas J.-S. , Le Pol J. , Gillet S. , Phan L.
Published: May 2018

In a sustainable development context, the storm water reuse in industry seems a promising and original alternative, but few experiences exist. A project, sponsored by the European Community and the Artois-Picardie Water Agency, has been carried out by the Renault MCA factory in Maubeuge, demonstrating that it can be profitable, in certain conditions, to reuse storm water in industrial processes. This article summarises this experience, and presents a decision making tool (SIRRUS) that has been developed in this framework by Anjou Recherche (Vivendi Water) to evaluate, on the basis of simple criteria, if this experience is or is not reproducible on a given site, and how much time is necessary to pay the investment back. Its application and different results are also discussed.
Integrated modelling as an analytical and optimisation tool for urban watershed management
Authors: Erbe V. , Frehmann T. , Geiger W.F. , Krebs P. , Londong J. , Rosenwinkel K.-H. , Seggelke K.
Published: May 2018

In recent years numerical modelling has become a standard procedure to optimise urban wastewater systems design and operation. Since the models were developed for the subsystems independently, they did not support an integrated view to the operation of the sewer system, the wastewater treatment plant (WWTP) and the receiving water. After pointing out the benefits of an integrated approach and the possible synergy effects that may arise from analysing the interactions across the interfaces, three examples of modelling case studies carried out in Germany are introduced. With these examples we intend to demonstrate the potential of integrated models, though their development cannot be considered completed. They are set up with different combinations of self-developed and commercially available software. The aim is to analyse fluxes through the total wastewater system or to integrate pollution-based control in the upstream direction, that is e.g. managing the combined water retention tanks as a function of state variables in the WWTP or the receiving water. Furthermore the interface between the sewer and the WWTP can be optimised by predictive simulations such that the combined water flow can be maximised according to the time- and dynamics-dependent state of the treatment processes.
Diffuse emission and control of copper in urban surface runoff
Authors: Boller M.A. , Steiner M.
Published: May 2018

Copper washed off from roofs and roads is considered to be a major contribution to diffuse copper pollution of urban environments. In order to guarantee sustainable protection of soils and water, the long-term strategy is to avoid or replace copper containing materials on roofs and façades. Until achievement of this goal, a special adsorber system is suggested to control the diffuse copper fluxes by retention of copper by a mixture of granulated iron-hydroxide (GEH) and calcium carbonate. Since future stormwater runoff concepts are based on decentralised runoff infiltration into the underground, solutions are proposed which provide for copper retention in infiltration sites using GEH adsorption layers. The example of a large copper façade of which the runoff is treated in an adsorption trench reveals the first full-scale data on façade runoff and adsorber performance. During the first year of investigation average façade runoff concentrations in the range of 1-10 mg Cu/l are reduced by 96-99% in the adsorption ditch.
Effect of long-term conventional tillage and no-tillage systems on soil and water quality at the field scale
Authors: Tan C.S. , Drury C.F. , Reynolds W.D. , Gaynor J.D. , Zhang T.Q. , Ng H.Y.
Published: May 2018

No-tillage (NT) is becoming increasingly attractive to farmers because it clearly reduces soil erosion and production costs relative to conventional tillage (CT). However, the impacts of no-tillage on the quantity and quality of tile drainage water are less well known. Accordingly, two adjacent field scale on-farm CT and NT sites were established to compare the impacts of the two tillage systems on tile drainage and NO3-N loss in tile drainage water. The effect of the two tillage systems on soil structure, hydraulic conductivity, and earthworm population were also investigated. The total NO3-N loss in tile drainage water over the 5-yr period (1995-1999) was 82.3 kg N ha−1 for the long-term NT site and 63.7 kg N ha−1 for the long-term CT site. The long-term NT site had 48% more tile drainage (6,975 kL ha−1) than the long-term CT site (4,716 kL ha−1). The average flow weighted mean (FWM) NO3-N concentration in tile drainage water over the 5-yr period was 11.8 mg N L−1 for the NT site and 13.5 mg N L−1 for the CT site. For both tillage systems, approximately 80% of tile drainage and NO3-N loss in tile drainage water occurred during the November to April non-growing season. Long-term NT improved wet aggregate stability, increased near-surface hydraulic conductivity and increased both the number and mass of earthworms relative to long-term CT. The greater tile drainage and NO3-N loss under NT were attributed to an increase in continuous soil macropores, as implied by greater hydraulic conductivity and greater numbers of earthworms.
Designing cost effective water demand management programs in Australia
Authors: White S.B. , Fane S.A.
Published: May 2018

This paper describes recent experience with integrated resource planning (IRP) and the application of least cost planning (LCP) for the evaluation of demand management strategies in urban water. Two Australian case studies, Sydney and Northern New South Wales (NSW) are used in illustration. LCP can determine the most cost effective means of providing water services or alternatively the cheapest forms of water conservation. LCP contrasts to a traditional approach of evaluation which looks only at means of increasing supply. Detailed investigation of water usage, known as end-use analysis, is required for LCP. End-use analysis allows both rigorous demand forecasting, and the development and evaluation of conservation strategies. Strategies include education campaigns, increasing water use efficiency and promoting wastewater reuse or rainwater tanks. The optimal mix of conservation strategies and conventional capacity expansion is identified based on levelised unit cost. IRP uses LCP in the iterative process, evaluating and assessing options, investing in selected options, measuring the results, and then re-evaluating options. Key to this process is the design of cost effective demand management programs. IRP however includes a range of parameters beyond least economic cost in the planning process and program designs, including uncertainty, benefit partitioning and implementation considerations.