bluuebunny/crossref_metadata_2025 huggingface dataset:
Alternatives for upgrading the Wilderness Wastewater Treatment Plant for biological nutrient removal
Authors: Cokgor E.U. , Randall C.W.
Published: May 2018

The Wilderness Wastewater Treatment Plant (WWTP) located in Orange County, Virginia is a four concentric ring oxidation ditch activated sludge system with a rated capacity of 1,935 m3/day. The three outer rings are used for wastewater treatment and the inner ring is used as an aerobic digester. The flow capacity has been increased from 1,935 to 3,760 m3/d, however, the desired design capacity has since been increased to 3,870 m3/d, and there are plans to eventually expand to approximately 4,840 m3/d with improved nitrogen removal. The design goal for the planned upgrade is to discharge an effluent that contains less than 10 mg/l total nitrogen (TN) at all times, with an annual average of 8 mg/l or less. In this study, the pre-upgrade performance of the Wilderness Wastewater Treatment Plant was evaluated and several modifications were recommended for the incorporation of biological nutrient removal (BNR).
Direct filtration with preozonation for small water treatment systems
Authors: Yüksel E. , Akgiray Ö , Soyer E.
Published: May 2018

The possibility of applying preozonation followed by direct filtration without the use of a coagulant is investigated. Filtration experiments have been carried out using four different water sources within Istanbul. A 1 m deep bed of 0.8-1.2 mm silica sand was used as the filter medium. The filter was operated at a rate of 11.5 m/hr. Raw water turbidities ranged from 2.3 NTU to 10.0 NTU. Effluent turbidity and particle count values were monitored using an on-line turbidimeter and an on-line particle counter. With all the waters studied in this work, preozonation improved particle removal in direct filtration. With three of the mentioned waters, it was possible to achieve turbidity values below 1.0 NTU without a coagulant by applying ozone at a rate between 1.7-1.8 mg/L. It was not possible to reduce the turbidity of one of the waters to below 2.7 NTU even with very high ozone dosages. The need for pilot testing before deciding if this treatment method is applicable to a given water is underlined.
Microbiological characterization of winery effluents: an inventory of the sites for different treatment systems
Authors: Jourjon F. , Khaldi S. , Reveillere M. , Thibault C. , Poulard A. , Chretien P. , Bednar J.
Published: May 2018

In a more and more regulated and socially pressured environment, the durable management of winery effluents must take into account their characteristics and their potential impact on their natural setting. The object of this exploratory study is to establish an inventory of the microbiological composition of winery effluents coming from different treatment systems. We have observed that winery effluents are charged with micro-organisms, by a factor that ranges from 105 to 108 UFC/ml, and that the level of "microbiological pollution" is independent of the type of system. The composition of the flora is closely tied to the time of year and therefore to winery activities, so certain micro-organisms will be favoured in certain periods and others will have a tendency to decrease. We have seen that from one year to another our observations remain identical; the flora equilibrium therefore occurs systematically and naturally. Faecal germs are found in very small quantities in winery effluent treatment systems. They represent minor sanitary risks. Good correlations were observed between some micro-organisms and some physical-chemical parameters (COD). It is, however, difficult to use these "easy-to-measure" parameters as reliable markers of certain microbial populations.
Application of Activated Sludge Model No. 1 to biological treatment of pure winery effluents: case studies
Authors: Stricker A.-E. , Racault Y.
Published: May 2018

The practical applicability of computer simulation of aerobic biological treatment systems for winery effluents was investigated to enhance traditional on-site evaluation of new processes. As there is no existing modelling tool for pure winery effluent, a model widely used for municipal activated sludge (ASM1) was used. The calibration and validation steps were performed on extended on-site data. The global soluble COD, DO and OUR were properly reproduced. Possible causes for the remaining discrepancies between measured and simulated data were identified and suggestions for improvement directions were made to adapt ASM1 to winery effluents. The calibrated model was then used to simulate scenarios to evaluate the plant behaviour for different operation or design. In combination with on-site observations, it allowed us to establish useful and justified improvement suggestions for aeration tank and aeration device design as well as feed, draw and aeration operation.
Odorous compounds treatment of winery and distillery effluents during natural evaporation in ponds
Authors: Bories A. , Sire Y. , Colin T.
Published: May 2018

During treatment of winery and distillery wastewater by natural evaporation in ponds, formation of malodorous compounds induces harmful olfactory effects. In this work, we studied the origin of malodorous compounds and methods to prevent and treat odours. The formation of volatile fatty acids (VFA) from pure substrates (glycerol, lactic and tartaric acids, ethanol) and complex media (winery and distillery wastewater) was studied. Various anaerobic bacteria ferment the glycerol and produce butyric or propionic acid. Valeric and caproic acids were observed at lower concentrations than butyric and propionic acids, but their malodorous intensities were higher. Microflora produce butyric, valeric, caproic, heptanoic and octanoic acids from ethanol, the main component of winery wastewater. When nitrate (an electron acceptor) is added, catabolism leads to an anaerobic respiration phenomenon (denitrification). The organic compounds are oxidised to CO2 and the nitrate is reduced to N2 (odourless compounds), without VFA formation. The preventive treatment of odours by nitrate addition was tested on an industrial scale in winery and distillery ponds. Furthermore, the study took the effect of nitrate on VFA degradation into consideration. The results make it possible to consider using nitrate for the curative treatment of pond odours.
Can geotextiles modify the transfer of heavy metals transported by stormwater in infiltration basins?
Authors: Lassabatère L. , Winiarski T. , Galvez-Cloutier R.
Published: May 2018

Geotextiles are fibrous materials increasingly employed for the design of infiltration basins. However, their influence on the transfer of contaminants carried by stormwater has not been fully investigated. This study, based on column leaching experiments, aims at showing the effect of geotextiles on the transfer of three heavy metals (Zn, Pb and Cd) in a reactive soil (simulating an infiltration basin at laboratory scale). This effect depends on several factors, such as type of geotextile, hydric conditions (geotextile water content), hydraulic conditions (flow-rates) and the number of geotextiles installed. In all cases, geotextiles influence heavy metal retention by modifying flow and thus regulating contact between these metals and the reactive soil.
The influence of biodegradability of sewer solids for the management of CSOs
Authors: Sakrabani R. , Ashley R.M. , Vollertsen J.
Published: May 2018

The re-suspension of sediments in combined sewers and the associated pollutants into the bulk water during wet weather flows can cause pollutants to be carried further downstream to receiving waters or discharged via Combined Sewer Overflows (CSO). A typical pollutograph shows the trend of released bulk pollutants with time but does not consider information on the biodegradability of these pollutants. A new prediction methodology based on Oxygen Utilisation Rate (respirometric method) and Erosionmeter (laboratory device replicating in-sewer erosion) experiments is proposed which is able to predict the trends in biodegradability during in-sewer sediment erosion in wet weather conditions. The proposed new prediction methodology is also based on COD fractionation techniques.
Use of 3D modelling and several ultrasound sensors to assess overflow rate
Authors: Lipeme Kouyi G. , Vazquez J. , Gallin Y. , Rollet D. , Sadowski A.G.
Published: May 2018

A new instrumentation mode has been put in place in order to determine the overflow rate of five complex CSOs of the system in Sélestat (French), which are subject to self monitoring. 3D and 1D models have made it possible to predict the shapes of the water lines and suggest a location for the ultrasound sensors. In order to validate the instrumentation principle, three overhead sensors were placed on a weir. The overflow laws suggested are of the type Qoverflow = a1h1b1 + a2h2b2 + a3h3b3. Early results of the overflow rate that have been obtained by applying the law are close to 10% of the flow measured in the physical test bench. On the actual site, the ultrasound sensors were assembled on a rail covering the entire weir in order to be able to change their position in future after models calibration.
Development of the real-time control (RTC) system for Tokyo sewage system
Authors: Maeda M. , Mizushima H. , Ito K.
Published: May 2018

Tokyo Metropolitan government has decided to make the maximum possible use of the existing facilities while ensuring safety against inundation and to promote measures also from a software approach by introducing a system capable of minimizing combined sewer overflow, the real-time control system (RTC). A pilot RTC system was installed in August 2002 for the Shinozaki Pumping Station. The RTC system monitors the precipitation volume and the water level in the pipe. Simulations were carried out on the basis of these data. From the results, it was found that with the use of the RTC it is possible to reduce CSO by roughly 50% for small rainfalls with a total precipitation level of 20 mm or less by strong rainwater in the pipe routes at the beginning of the rain. It has also been shown that CSO can be reduced by about 80% through the use of rainfall forecasting.
Computational fluid dynamic prediction of the residence time of a vortex separator applied to disinfection
Authors: Egarr D. , Faram M.G. , O'Doherty T. , Phipps D. , Syred N.
Published: May 2018

A Hydrodynamic Vortex Separator (HDVS) has been modelled using Computational Fluid Dynamics (CFD) in order to predict the residence time of the fluid at the overflow and underflow outlets. A technique which was developed for use in Heating, Ventilation and Air Conditioning (HVAC) was used to determine the residence time and the results have been compared with those determined experimentally. It is shown that in using CFD, it is possible to predict the mean residence time of the fluid and to study the response to a pulse injection of tracer. It is also shown that it is possible to apply these techniques to predict the mean survival rate of bacteria in a combined separation and disinfection process.
Sewer solids—20 years of investigation
Authors: Ashley R. , Bertrand-Krajewski J.-L. , Hvitved-Jacobsen T.
Published: May 2018

Knowledge about sewer solids has advanced rapidly in the last few decades due to academic research triggered by an emerging renewed interest from sewer operators. It is now known that sewer solids are implicated in: loss of conveyance; potential for acute and chronic pollution of watercourses and effects inside sewers such as generation of malodorous gases and fabric corrosion. Despite this advance in knowledge, there is much that still needs to be understood, particularly the details of some of the mechanisms of flow-solids interactions, such as deposition, consolidation, erosion, biochemical interactions and processes. The history of knowledge development is outlined and areas where there is a need for further elucidation are highlighted.
Identification of overall degradation in sewer systems from long-term measurements and consequences for WWTP simulations
Authors: Ahnert M. , Kuehn V. , Krebs P.
Published: May 2018

In-sewer transformation processes affect significantly design and operation of large wastewater treatment plants. Especially for long-term simulations the degradation has to be considered in order to avoid over- and underestimation. In this paper a method is presented to derive the overall degradation from available operation data. The application of the results in a long-term simulation of a WWTP shows the relevance of the degradation for design and operation of an activated sludge plant.
Upgrading of Florence wastewater treatment plant: co-digestion and nitrogen autotrophic removal
Authors: Caffaz S. , Canziani R. , Lubello C. , Santianni D.
Published: May 2018

In recent years a completely autotrophic nitrogen removal process based on Anammox biomass has been tested in a few European countries in order to treat anaerobic supernatant and to increase the COD/N ratio in municipal wastewater. This work reports experimental results on a possible technical solution to upgrade the S. Colombano treatment plant which treats wastewater from the Florentine urban area. The idea is to use 50% of the volume of the anaerobic digester in order to treat external sewage sludge (as septic tank sludge) together with waste activated sludge and to treat the resulting effluent on a SHARON-ANAMMOX process in order to remove nitrogen from the anaerobic supernatant. Anaerobic co-digestion, tested in a 200 L pilot plant, enables low cost treatment of septic tank sludge and increases biogas production; however, it also increases the nitrogen load re-circulated to the WWTP, where nitrogen removal efficiency is already low (<50%), due to the low COD/N ratio, which limits predenitrification efficiency. Experimental results from a SHARON process tested in a lab-scale pilot plant show that nitrite oxidising bacteria are washed-out and steady nitrite production can be achieved at retention times in the range 1–1.5 days, at 35 °C. In a lab-scale SBR reactor, coupled with a nitration bioreactor, maximum specific nitrogen removal rate under nitrite-limiting conditions (with doubling time equal to about 26 days at 35 °C) was equal to 0.22 kgN/kgSSV/d, about 44 times the rate measured in inoculum Anammox sludge. Finally, a cost analysis of the proposed upgrade is reported.
Performance analysis of anoxic selector in upgrading activated sludge process in tropical climate
Authors: Cao Y.S. , Teo K.H. , Yuen W.A. , Long W.Y. , Seah B.
Published: May 2018

The paper describes and analyses the performance of anoxic selectors in upgrading activated sludge process in a municipal wastewater treatment plant under tropical climate, where poor sludge settleability is a problem due to elevated temperature. Site monitoring and laboratory experiment were conducted to study the denitrification, sludge settleability, kinetics, mass balance, pH and alkalinity variation in the system. The sludge settleability measured in Sludge Volume Index (SVI) was observed to improve with the increasing degree of denitrification in the anoxic selector. Under well-developed stable state, an average SVI value of 136 ml/g was achieved, which was significantly lower than the value of 250 ml/g before the application of anoxic selector. The specific reaction rates for denitrification and nitrification at 30°C were 0.06 mg NO3-N/mg MLSS day and 0.08 mg NH4-N/mg MLSS day, respectively. The overall efficiencies of nitrification and denitrification were 86 percent and 55.4 percent, respectively, with an alkalinity recovery ratio of 15.4 percent. 32 percent of total COD removed was used up as electron donor in the denitrification process. However, due to absence of the internal Mixed Liquor Recirculation (MLR), a higher degree of denitrification occurred in the secondary sedimentation tank than in the anoxic zone. Issues for further studies are also discussed.
Upgrading of existing aerobic plants with the LUCAS anaerobic system based on full-scale experiences
Authors: Gerards R. , Gils W. , Vriens L.
Published: May 2018

It has been demonstrated that the combination of anaerobic–aerobic treatment is the best technological and economical solution for the treatment of high loaded wastewater. Where in the past aerobic treatment systems were still very acceptable due to the very good treatment efficiency, simplicity and robustness of the technology, this has, in most cases, been changed due to very stringent sludge disposal legislation. The anaerobic pretreatment takes care of approximately 80–90% of the overall treatment efficiency at high loading rates and low sludge production and low energy costs. The aerobic posttreatment takes care of the absolute high removal efficiency and nitrogen and phosphorus removal. Because of the low organic loading rate of the aerobic posttreatment also in this stage the sludge production is low. The combination of anaerobic–aerobic treatment results in a compact system capable of reaching high treatment efficiency at low sludge production and lower energy consumption. Waterleau Global Water Technology has developed LUCAS® anaerobic–aerobic system that combines an Upflow Anaerobic Sludge Blanket (UASB) reactor with an aerobic, constant-level cyclic activated sludge system, which is very suitable for the treatment of high loaded wastewaters in general and brewery waste water in particular. It has been proven from several full scale upgrading projects that the UASB system is best suitable for implementation in the aerobic plants that have to be extended in capacity.
Precipitation variability in the Meuse basin in relation to atmospheric circulation
Authors: Tu M. , de Laat P.J.M. , Hall M.J. , de Wit M.J.M.
Published: May 2018

The distribution of precipitation events in the Meuse basin during the past century has been found to reflect the large-scale atmospheric circulation, as characterised by the Grosswetterlagen system. Statistical analysis of the long observation records (1911–2002) for the basin showed that although the annual (November to October) and winter half-year (November to April) frequencies of wet days (≥1 mm/day) were nearly stable, the associated precipitation amounts have significantly increased since 1980. From 1980 onwards, the very wet days (≥10 mm/day) in the winter half-year have become more frequent. No obvious change was identified for the summer half-year (May to October) very wet days. Both the precipitation amounts of wet and very wet days in the winter half-year and the occurrence of associated atmospheric circulation of the types/sub-types west cyclone, southwest cyclone and northwest cyclone showed a significant increase around 1980.
Climatic change and the effect on hydrology and water management in the Rhine basin
Authors: Krahe P. , Buiteveld H. , Pfister L. , Ritz Ch. , Sprokkereef E.
Published: May 2018

There has been a marked increase in recent years in the resources dedicated to investigating the problems arising from climate change with respect to hydrology and to some extent to water resource management. Many of these studies are concentrated on the river Rhine basin. In order to review the actual state of scientific findings a workshop, organised by the International Commission for the Hydrology of the Rhine (CHR), was held on 24 and 25 June 2003. The invited experts discussed the following topics: observed variability in climatic and hydrological data, the development and interpretation of climate scenarios, and assessment of changes in the discharge regimes and the occurrence of hydrological extremes. Based on the workshop the question of whether or not current knowledge and procedural strategies can be used as a basis for future water management was evaluated by an expert group of the CHR. In this paper the process of decision-making with regard to flood management is analysed. Hints are given to convince the decision-makers to take into account the impacts of climate change in water resources management. The special challenges arising in international river basins are discussed.
Some rationales for risk sharing and financing adaptation
Authors: Bouwer L.M. , Vellinga P.
Published: May 2018

Current climate variability and anticipated climate change challenge our water systems and our financial resources. The sharing of economic losses due to weather related hazards and the sharing of costs that result from protecting lives and property take place in different forms, but are currently insufficient. In this paper we discuss three different rationales for financing disaster losses through public and private arrangements, as well as options for financing adaptation, with a special focus on water management. We propose that financial arrangements for risk sharing and climate change adaptation should be reconsidered, in a more structured approach, to be able to deal with both disaster losses and the costs that arise because of climate change adaptation, e.g. for water management, in both developing and developed countries.
Development of perspective-based water management strategies for the Rhine and Meuse basins
Authors: van Deursen W.P.A. , Middelkoop H.
Published: May 2018

Water management is surrounded by uncertainties. Water management thus has to answer the question: given the uncertainties, what is the best management strategy? This paper describes the application of the perspectives method on water management in the Rhine and Meuse basins. In the perspectives method, a structured framework to analyse water management strategies under uncertainty is provided. Various strategies are clustered in perspectives according to their underlying assumptions. This framework allows for an analysis of current water management strategies, but also allows for evaluation of the robustness of proposed future water strategies. It becomes clear that no water management strategy is superior to the others, but that inherent choices on risk acceptance and costs make a real political dilemma which will not be solved by further optimisation.
Flood management under climatic variability and its future perspective in Japan
Authors: Ikeda T. , Yoshitani J. , Terakawa A.
Published: May 2018

Devastating magnitudes of flood disasters have been occurring in various areas of Japan, and their impact has been increasing in recent years. Looking ahead, it is foreseen that rainfall and its patterns will be altered due to the climate change accompanied by global warming, and there is concern that the intensity and frequency of flood disasters might be exacerbated. This paper aims to introduce flood characteristics and management policies in Japan that have been undertaken for a long time in order to mitigate these recurrent flood disasters. It also highlights extremely devastating floods in some areas that occurred under recent climate variability, and to address the progress in the assessment of hydro-meteorological tendencies and in the promotion of dialogue among climatologists and hydrologists. Lastly, a new initiative to establish an international centre on water-related hazards and its risk management is presented.
Bayesian analysis for erosion modelling of sediments in combined sewer systems
Authors: Kanso A. , Chebbo G. , Tassin B.
Published: May 2018

Previous research has confirmed that the sediments at the bed of combined sewer systems are the main source of particulate and organic pollution during rain events contributing to combined sewer overflows. However, existing urban stormwater models utilize inappropriate sediment transport formulas initially developed from alluvial hydrodynamics. Recently, a model has been formulated and profoundly assessed based on laboratory experiments to simulate the erosion of sediments in sewer pipes taking into account the increase in strength with depth in the weak layer of deposits. In order to objectively evaluate this model, this paper presents a Bayesian analysis of the model using field data collected in sewer pipes in Paris under known hydraulic conditions. The test has been performed using a MCMC sampling method for calibration and uncertainty assessment. Results demonstrate the capacity of the model to reproduce erosion as a direct response to the increase in bed shear stress. This is due to the model description of the erosional strength in the deposits and to the shape of the measured bed shear stress. However, large uncertainties in some of the model parameters suggest that the model could be over-parameterised and necessitates a large amount of informative data for its calibration.
Development and implementation of a real-time control strategy for the sewer system of the city of Vienna
Authors: Fuchs L. , Beeneken T.
Published: May 2018

The paper describes the realization of a real-time control for the Vienna sewer system. The project is scheduled for completion for 2004. The 3.5 year project comprises all planning stages starting with the recording of data up to the planning of measuring and controlling units. The concrete steps of the planning stages are explained. A measuring system including 25 rainfall measurements, 40 flow measurements and 20 water level measurements is implemented as an online system. This measuring system is designed to achieve two objectives, on the one hand the real-time control and on the other hand the calibration of the model that is used for the hydrodynamic sewer system simulation. The approx. 53,000 pipes have served to generate a coarse network of no more than approx. 2,600 pipes. The area data were derived with high accuracy from available aerial photograph interpretations. With simulation runs of a rule-based control software the system operation was examined. A self-learning system will improve the rule basis. A forecasting model that uses weather observation radar will additionally influence the controlling decisions. The findings from the investigations are immediately considered in the planning of measuring and control units. The simulated results for the first phase of implementation, which demonstrate the benefit of RTC for the Vienna sewer system, are explained.
The post-normal sciences of precaution
Authors: Ravetz J.
Published: May 2018

After centuries of optimism, science has become problematic and compromised. We can no longer assume that innovations are safe until proven dangerous. The ‘technocratic’ approach to science, with its reductionist methodology and its corporate control, is no longer appropriate. We need a ‘precautionary’ science that will be ‘post-normal’ in character. For this, we contrast ‘applied science,’ like the ‘puzzle-solving’ of Kuhn's ‘normal science’ and the ‘professional consultancy’ like the practice of the surgeon or engineer. Rather, we have a situation where ‘facts are uncertain, values in dispute, stakes high, and decisions urgent.’ For high-quality decision-making, we need an ‘extended peer community’ who will bring their ‘extended facts’ to the dialogue. There are a number of initiatives that advance the post-normal programme, including the endeavours of Poul Harremoës and the conference on Uncertainty and Precaution in Environmental Management.
Globalisation, environmental harm, and progress:the role of consensus and liability
Authors: Zandvoort H.
Published: May 2018

Two conditions are stated that must be fulfilled to make sure that the negative effects of environmental pollution and risks stemming from the spread of free markets and technology do not outweigh the beneficial effects of this development. (1) For all activities, all those who may experience the negative effects of the activities must have given their consent to the activities and the conditions under which they are performed. (2) Those who engage in activities without this consent must be held to unlimited and unconditional liability for the negative effects that the activities may cause for those who did not give their consent. These conditions are necessary principles for the responsible management of environmental harm and risks. If the conditions are not satisfied, then the belief that the global spread of free markets and technology is beneficial for all, or does not harm anyone, cannot be justified. Neither of the conditions is fulfilled at present. This is illustrated using examples drawn from international legislation regarding liability for oil transportation, energy production, genetically modified organisms and chemicals in the environment. Directions for improving existing liability legislation are identified. The relationship between the conditions and the precautionary principle is explained.
Sources of uncertainty in economic analysis of the Water Framework Directive
Authors: Myšiak J. , Sigel K.
Published: May 2018

The Water Framework Directive (WFD) imposes a new approach to water resource management in the EU states. Uncertainty surrounding its implementation, however, could badly affect the achievement of the objectives set by the Directive. Although not directly linked to a set of techniques to deal with it, the WFD and accompanying guidance documents mention uncertainty as a relevant factor in implementing the WFD and especially in the context of economic analysis of water uses. In this paper we review several sources of uncertainty surrounding economic analysis focusing on uncertainty related to socioeconomic descriptors of river basins and water uses and uncertainty surrounding the selection of measures (WFD article 11). While a number of sources of uncertainty in socioeconomic descriptors of river basins and water uses are discussed, we argue that the transformation of this information into hydrological spatial units may turn out to be a real challenge for uncertainty assessment. For the choice of the most appropriate measures, we distinguish between uncertainty being ‘internalised’ in decisions (by using stochastic decision methods) and uncertainty stemming from the application of these methods.
Uncertainty and precaution in European environmental risk assessment of chemicals
Authors: Verdonck F.A.M. , Van Sprang P.A. , Vanrolleghem P.A.
Published: May 2018

It is recognised that there is a need for a proper treatment and transparency of uncertainty in risk assessment and management, especially in view of the upcoming proposed new chemical policy REACH, which delegates the responsibility for conducting risk assessments to industry. The current EU risk assessment for new and existing substances is largely deterministic and prudential measures are implicitly embedded in calculation schemes and rules. In this paper, a more probabilistic approach to risk assessment is advocated. The advantage is twofold: 1) inherent variability and other uncertainty pertaining to exposure and effects are transparently taken into account, while at the same time 2) issues of caution are explicitly transferred to the risk management phase. The result of a probabilistic risk assessment as suggested is improved transparency with quantitative and qualitative uncertainty estimates. Such uncertainty information can be used to discuss precautionary measures in the context of risk management.
Resources and uncertainties in evaluation of chemicals: basic methodological developments
Authors: Sørensen P.B. , Lerche D.B. , Brüggemann R.
Published: May 2018

Conscious handling of uncertainty is critical in the assessment of chemicals, where the demand of knowledge is high compared to the available amount of resources. Consequently weighing between the use of resources and the acceptance of uncertainty has to be a transparent process and this sets up a challenge in relation to the application of mathematical methods. The maximum entropy principle is a useful paradigm for setting up prior information that is as non-informative as possible. It is shown how the use of partial ordering for deriving ranking results can be considered as a maximum entropy strategy in relation to the model structure uncertainty. In this way it seems possible to solve central parts of the problem of resource optimising risk assessment by combining the precautionary principle and screening before more detailed risk assessment is undertaken. The non-parametric approach of partial order technique further appears to be more transparent than most other ranking methodologies for complex systems. Because in the partial order techniques, no more or less known uncertainty will be hidden in the application of specific weighting factors and functional relationships among the criteria.
High biofilm activity under increased oxygen concentrations in a pressurised biofilm system
Authors: Janning K.F. , Bak S.N. , Andersen M. , Kristensen G.H.
Published: May 2018

A new pressurised biofilm reactor (PBR) process with a patented disc system that enables constant biofilm control has been developed to treat concentrated wastewater with respect to easily degradable organic matter under pressures of up to 6 bar. The pressurisation enables a six-fold increase of the O2 saturation level and aeration capacity, which potentially increases the reaction rate of COD as long as O2 is limiting the reaction rate. Experiments performed in a pilot-scale PBR-reactor fed by synthetic wastewater were conducted to verify the potential and kinetics of heterotrophic conversion of O2 and acetate. Under O2-limited conditions the maximum removal rate of O2 and CODf was measured to rA,O2=60 g O2/m2/d and rA,CODf=150 g CODf/m2/d at 70 mg O2/l. Experiments verified that half-order kinetics could be applied but liquid film diffusion apparently influenced the reaction rate considerably. The observed half-order rate constant was experimentally determined to K½A,O2=7.0 (g O2)1/2m−1/2d−1 but this value is underestimated by 15% due to the observed liquid film diffusion. Based on this the intrinsic zero-order reaction rate was estimated at k0f,O2=190 kg O2/m3 biofilm/d when both liquid film and biofilm diffusion were taken into account.
Effect of hydrodynamic conditions on biofilm oxygen consumption rate in a fixed-bed nitrifying reactor
Authors: Carrión M. , Alba J. , Thalasso F.
Published: May 2018

The effect of the hydrodynamic conditions on oxygen consumption rate was studied in a fixed-bed nitrifying reactor. For that purpose, the kLa, the overall oxygen consumption rate and the maximum biofilm respiration rate were measured under several mixing powers. It was observed that the maximum biofilm respiration rate was dependent on the hydrodynamic conditions. From the results obtained, a simplistic model was developed to predict the overall oxygen consumption rate from the mixing power applied.
Experimental and numerical results of a single submerged attached growth bioreactor for simultaneous oxidation of organics and nitrogen removal
Authors: Pedros P.B. , Wang J.Y. , Dobie W.K. , Metghalchi H.
Published: May 2018

Two primary advantages of a submerged attached growth bioreactor (SAGB) are the small volume requirement and the elimination of downstream clarification. While different configurations of SAGBs have been developed for various applications, the use of a single SAGB for achieving the combined removal of organics and nitrogen has not been extensively studied. This research studied the microbial kinetics of a multispecies biofilm within a single-unit, single-zone SAGB designed to achieve the combined removal of both carbonaceous organics and nitrogen. A pilot-scale SAGB plant was developed and operated to treat a municipal wastewater to an effluent BOD5≤30 mg/l, TSS≤30 mg/l, and total nitrogen≤10 mg/l. At a total organic loading of 4.0 kg/m3-day adequate nitrogen removal, resulting in an effluent total nitrogen of 8.5 mg/l, was achieved. The numerical simulation of reactor performance using AQUASIM showed good agreement in overall trends. This research demonstrated an expanded and improved application of a multispecies biofilm process for wastewater nutrient removal.
Simulation of turbulence and dissolved oxygen concentration profiles over biofilm using k–ɛ turbulence model
Authors: Nagaoka H. , Sanda K.
Published: May 2018

The objective of this study is to investigate the flow structure over biofilm experimentally and theoretically. Velocity and turbulence profiles over biofilm measured by a laser Doppler velocimetry were compared to simulated profiles using the k–ɛ turbulent model. Also, dissolved oxygen concentration profiles over biofilm are measured using a micro DO sensor. The k–ɛ turbulence model was proved to be a useful tool for the understanding of mass transfer inside and outside biofilm. Dissolved oxygen concentration profile inside and outside biofilm showed the existence of turbulent diffusion inside biofilm.
Behaviour of pharmaceuticals and personal care products in a sewage treatment plant of northwest Spain
Authors: Carballa M. , Omil F. , Lema J.M. , Llompart M. , García C. , Rodriguez I. , Gómez M. , Ternes T.
Published: May 2018

Thirteen pharmaceutical and cosmetic compounds have been surveyed along the different units of a municipal sewage treatment plant (STP) to study their fate across each step and the overall removal efficiency. The STP studied corresponds to a population of approximately 100,000 inhabitants located in Galicia (northwest Spain), including three main sections: pre-treatment (coarse and fine screening, grit and fat removal); primary treatment (sedimentation tanks); and secondary treatment (conventional activated sludge). Among all the substances considered (galaxolide, tonalide, carbamazepine, diazepam, diclofenac, ibuprofen, naproxen, estrone, estradiol, ethinylestradiol, roxitromycin, sulfamethoxazole and iopromide), only significant concentrations were found for two musks (galaxolide and tonalide), two antiphlogistics (ibuprofen and naproxen), two natural estrogens (estrone, estradiol), one antibiotic (sulfamethoxazole) and the X-ray contrast media (iopromide), being the other compounds below the quantification level. In the primary treatment, only the fragrances were partly removed, with efficiencies of 20–50% for galaxolide and tonalide. However, the aerobic treatment caused an important reduction in all compounds detected, between 35 and 75%, with the exception of iopromide. The overall removal efficiency of the STP ranged between 70 and 90% for the fragrances, 45 and 70% for the acidic compounds, around 67% for estradiol and 57% for the antibiotic sulfamethoxazole.
A single well push–pull test method for in situ determination of denitrification rates in a nitrate-contaminated groundwater aquifer
Authors: Kim Y. , Kim J.H. , Son B.H. , Oa S.W.
Published: May 2018

In this study a single-well, “push–pull” test method is adapted for determination of in situ denitrification rates in groundwater aquifers. The rates of stepwise reduction of nitrate to nitrite, nitrous oxide, and molecular nitrogen were determined by performing a series of push–pull tests. The method consists of the controlled injection of a prepared test solution (“push”) into an aquifer followed by the extraction of the test solution/ground water mixture (“pull”) from the same location. The injected test solution consists of ground water containing a nonreactive tracer and one or more biologically reactive solutes. Reaction rate coefficients are computed from the mass of reactant consumed and/or product formed. A single Transport Test, one Biostimulation Test, and four Activity Tests were conducted for this study. Transport tests are conducted to evaluate the mobility of solutes used in subsequent tests. These included bromide (a conservative tracer), fumarate (a carbon and/or source), and nitrate (an electron acceptor). Extraction phase breakthrough curves for all solutes were similar, indicating apparent conservative transport of the solutes prior to biostimulation. Biostimulation tests were conducted to stimulate the activity of indigenous heterotrophic denitrifying microorganisms and consisted of injection of site ground water containing fumarate and nitrate. Biostimulation was detected by the simultaneous production of carbon dioxide and nitrite after each injection. Activity tests were conducted to quantify rates of nitrate, nitrite, and nitrous oxide reduction. Estimated zero-order degradation rates decreased in the order nitrate > nitrite > nitrous oxide. The series of push–pull tests developed and field tested in this study should prove useful for conducting rapid, low-cost feasibility assessments for in situ denitrification in nitrate-contaminated aquifers.
UN water action decade: a unique challenge and chance for water engineers
Authors: Wilderer P.A.
Published: May 2018

In the year 2000, the UN General Assembly resolved the Millennium Development Goals (MDGs), and all the Member States of the UN pledged to take any measures to get the MDGs achieved. Concerning water supply and sanitation, a rough calculation clearly tells that it is impossible to meet the MDGs by just copying and pasting the traditional technology as it has been developed in the industrialized countries. Novel concepts and technologies have to be developed, tested and made available which allow fast implementation for a reasonable price, and which provide high treatment efficiency, reliability and robustness. Based on the latest estimates on population growth and migration rates it appears that top priority should be given to investments in the water infrastructure of municipalities. Introduction of water re-use systems should be favoured to avoid over-exploitation of local water resources. Suggested are step changes of the infrastructural system components with emphasis on technology innovation. Many small steps are often more effective than a single big one. In the attempt to quickly improve local situations specific attention should be paid to modern physico-chemical methods based on membrane technology. Decentralized wastewater treatment and re-use methods should be installed simultaneously to the construction of new houses. Further development of methods for separate collection and treatment of particularly composed waste streams should be encouraged. Wastewater should be rated as a source of valuable materials rather than a nuisance. Technology development should proceed hand-in-hand with the development of the societal, economical and political framework. Concerted actions are necessary to make novel technology function. Otherwise, meeting of the MDGs will remain an illusion.
Quantitative systems analysis as a strategic planning approach for metropolitan water service providers
Authors: Lundie S. , Peters G. , Beavis P.
Published: May 2018

Sydney Water selected life cycle assessment (LCA) to inform a review of its overall strategic planning document: WaterPlan 21. This assessment covered the entire business and has enabled ecological sustainability to be assessed in terms of quantitative indicators. The LCA was performed by firstly examining a base case which would eventuate if Sydney Water maintained its current operations with only the modifications, augmentations and upgrades planned for implementation between now and 2021. We then performed a number of scenario analyses to examine the benefits of additional demand management, energy efficiency, energy generation, supply augmentation and effluent quality initiatives. The results indicated significant improvements are available and that some of these measures are more desirable than others. We also examined a scenario for the alternative delivery of water and wastewater services in new urban areas. This showed quantitatively that, since connecting new fringe suburbs to the existing system requires significant expenditure on energy for pumping, major improvements in the sustainability of water and wastewater systems can be achieved by using localised, water-saving alternatives.
An integrated approach for solving urban water and wastewater crises in the Arabian Gulf States
Authors: Nouh M.
Published: May 2018

Various environmental and economic aspects of urban water and wastewater crises in a number of the Arabian Gulf States are discussed. An integrated approach, which considers simultaneously the problems of urban waters (shortage of water supply and problems associated with urban drainage) and those in connection with wastewater (i.e. environmental impact) is proposed. The feasible link between the main factors affecting these problems and the anticipated results encourage the implementation of the proposed approach. The conclusions suggest immediate municipal legislation.
Analysis and evaluation of methodologies to assess technical urban water systems
Authors: Starkl M. , Brunner N. , Grasser U. , Moog O. , Stagl S. , Kärrman E. , Wimmer J. , Szewieczek R. , Haberl R.
Published: May 2018

The paper reports on the methodology and findings of a recent project on behalf of the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management. The Ministry is seeking procedures for combining ecological and economic criteria to assess which technical urban water alternatives shall receive funding. To this end the current decision making process (DMP) for implementing urban water alternatives in Austria has been analyzed and compared with the situation elsewhere, e.g. in Sweden. The DMP entails specific requirements on assessment, whence the most common decision aid methodologies, ranging from LCA-based to multi-criteria methods, have been described and evaluated from an environmental, economic, legal and practical point of view, turning out recommendations to the Ministry. Their main points are: First the DMP should be kept as simple as possible in order to make it transparent. Second the aggregation of different criteria groups should and can be avoided. Therefore the stakeholders should not be allowed to make trade-offs. Finally clear objectives need to be stated.
Treatment of dirty water from dairy farms using a soil-based batch recirculation system
Authors: Tyrrel S.F. , Leeds-Harrison P.B.
Published: May 2018

“Dirty water”, a wastewater produced on dairy farms, is typically disposed of by application to land with no prior treatment. Pollution can occur if the dirty water reaches a watercourse following an inadequate period of retention in the soil. This paper describes experiments using a novel, soil-based batch recirculation system for pre-treating dirty water prior to land application. Three polythene-lined, vegetated soil-based treatment planes (23 m long, 1 m wide, 0.25 m deep) were constructed. Each treatment plane was supplied with approximately 1 m3 of dirty water which was recirculated until a clear treatment pattern had emerged. Five batches were treated over a six-month period. The soil-based treatment system could typically be expected to achieve a 90% removal of key pollutants in approximately two weeks for BOD5 and NH4-N, and three weeks for MRP and total solids. An exponential trendline gave a good fit to the treatment curves for BOD5, NH4-N and MRP after the first day or two of batch treatment. The data for total solids removal were more variable. Treatment rates were sustained throughout the five runs for BOD5 and NH4-N, indicating no apparent effect of seasonal weather on the treatment process. The apparent progressive slowing of the MRP removal rate throughout the treatment of the five batches may have implications for the sustainable use of this technology for phosphorus control.