bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental abatement data of underflow baffles for removal of floatables in the CSOs of the Greater Montréal (Canada) area
Authors: Cigana John F. , Couture Martin
Published: May 2018

Underflow baffles have gained in popularity over the years as a viable mean to intercept floatables in Combined Sewer Overflows (CSOs). This choice was mainly justified by the extremely low capital cost (CAPEX) and operational cost (OPEX) of this solution, although the efficiency of underflow baffles has never been clearly proven. The only similar application to underflow baffles are scum boards in grit chambers and clarifier. However, the flow conditions at CSOs vary considerably from those in grit chambers and clarifier. For this reason, review of the behavior of floatables in a rapid flow is paramount. Only then can comprehensive design criteria for underflow baffles and overflow chambers be suggested. Pilot scale tests, performed in a 17 metres long basin at various flowrates, had already shown that a critical horizontal velocity for floatables (Vcr) may develop in the overflow chambers. In this follow up study, the fate of intercepted floatables was investigated. It appears from this latest data that permanent capture of floatables decreases rapidly with an increase in the horizontal velocity of the flow, no matter what the baffle depth. Baffle depth increases capture at lower velocities (0.17 m/s) but become irrelevant at higher velocities (0.61 m/s). This data suggests that capture efficiency of existing underflow baffles in overflow chambers can be, at best, very low whenever the horizontal velocity increases above 0.30 m/s or 1 ft/s.
Test of the efficiency of three storm water quality models with a rich set of data
Authors: Ahyerre M. , Henry F.O. , Gogien F. , Chabanel M. , Zug M. , Renaudet D.
Published: May 2018

The objective of this article is to test the efficiency of three different Storm Water Quality Model (SWQM) on the same data set (34 rain events, SS measurements) sampled on a 42 ha watershed in the center of Paris. The models have been calibrated at the scale of the rain event. Considering the mass of pollution calculated per event, the results on the models are satisfactory but that they are in the same order of magnitude as the simple hydraulic approach associated to a constant concentration. In a second time, the mass of pollutant at the outlet of the catchment at the global scale of the 34 events has been calculated. This approach shows that the simple hydraulic calculations gives better results than SWQM. Finally, the pollutographs are analysed, showing that storm water quality models are interesting tools to represent the shape of the pollutographs, and the dynamics of the phenomenon which can be useful in some projects for managers.
Advection-dispersion modelling tools: what about numerical dispersion?
Authors: Bouteligier R. , Vaes G. , Berlamont J. , Flamink C. , Langeveld J.G. , Clemens F.
Published: May 2018

In general the transport of dissolved substances and fine suspended particles is governed by the one-dimensional advection-dispersion equation. In order to model the transport of dissolved substances and fine suspended particles, the advection-dispersion equation is incorporated into commonly used urban drainage modelling tools such as InfoWorks CS (Wallingford Software, United Kingdom) and MOUSE (DHI Software, Denmark). Two examples show the use of InfoWorks CS and MOUSE using standard model settings. Modelling results using tracer experiments show that numerical model parameters need to be altered in order to calibrate the model. Using tracer experiments as a model calibration tool, it is shown that a non-negligible amount of dispersion is generated by InfoWorks CS and MOUSE and that it is in fact the numerical dispersion that is calibrated.
Forces on sanitary solids in small sewers
Authors: Butler D. , Littlewood K. , Orman N.
Published: May 2018

An experimental and modelling study has been carried out to investigate the movement mechanisms and behaviour of large sanitary solids in small sewers. The overall performance of the model has already been verified in terms of limiting solids transport distance, but in this paper the wave profile across the solid is also shown to fit model predictions well when compared visually. Further insight into how solids behave is also explored in this paper by plotting the interplay of the main horizontal and vertical forces acting on the solid. These results illustrate the dynamics of movement initiation, transport and deposition and indicate the most important forces. Model predictions of movement ‘time per hop’ have also been experimentally verified, giving further credence to the model. Experimental verification of the magnitude of the forces involved is planned.
Anoxic sulfide oxidation in wastewater of sewer networks
Authors: Yang W. , Vollertsen J. , Hvitved-Jacobsen T.
Published: May 2018

Investigations on anoxic sulfide oxidation in wastewater under sewer conditions are presented. Batch tests were designed and conducted to study both chemical and biological sulfide oxidation by nitrate in the water phase. Oxidation at pH 7.0 and 8.5 was performed in parallel and wastewater with anaerobic storage period of 0, 3, 4, 6 days was used. Initial sulfide concentrations at a level of 0–4.1 g S m−3 were applied by either addition or sulfate reduction. Results showed that wastewater in sewers was capable of biological, but not chemical, sulfide oxidation under anoxic conditions. Elemental sulfur was the end-product during the experiment. Nitrite accumulates in wastewater as an intermediate. The anoxic oxidation rates for fresh wastewater was 0.48 g S m−3 h−1 at pH 7.0 and 0.62 g S m−3 h−1 at pH 8.5, which accounted for less than 30% of the potential aerobic oxidation rates. A long-term anaerobic adaptation of the wastewater was found to inhibit the oxidation process.
Infiltration in sewer systems: comparison of measurement methods
Authors: De Bénédittis J. , Bertrand-Krajewski J.-L.
Published: May 2018

For 20 years, several methods for the estimation of infiltration have been developed in various countries. These conventional methods are subject to considerable uncertainties due to their underlying assumptions and general principles which are not estimated. Two extended comparative studies of the conventional methods have been made in order to assess the variability in infiltration estimations and associated uncertainties according to the method used. The choice of method is not critical when the objective of a sewer diagnostic study is to define the spatial distribution of infiltration contributions at sub-catchment scale. Nevertheless, the methods based on the analysis of the minimum night flow that are generally applied during one dry weather day should be applied during 8 to 10 dry weather days in order to provide estimations with acceptable uncertainties.
Coupling the SHARON process with Anammox: Model-based scenario analysis with focus on operating costs
Authors: Volcke E.I.P. , Van Hulle S.W.H. , Donckels B.M.R. , van Loosdrecht M.C.M. , Vanrolleghem P.A.
Published: May 2018

The combined SHARON-Anammox process for treating wastewater streams with high ammonia concentration is discussed. Partial nitritation in the SHARON reactor should be performed to such an extent that an Anammox-optimal nitrite:ammonium ratio is generated. The SHARON process is typically applied to sludge digestion rejection water in order to relieve the ammonium load recycled to the main plant.A simulation study for realistic influent conditions on a SHARON reactor with a fixed volume and operated with constant air flow rate reveals that the actual nitrite:ammonium ratio might deviate significantly from the ideal ratio and might endanger operation of the subsequent Anammox reactor. It is further examined how the nitrite:ammonium ratio might be optimized. A cascade pH control strategy and a cascade O2 control strategy are tested. Simulation results are presented and the performance of the different strategies is assessed and quantified in an economic way by means of an operating cost index. Best results are obtained by means of cascade feedback control of the SHARON effluent nitrite:ammonium ratio through setting an O2-set-point that is tracked by adjusting the air flow rate.
Impact of dimension uncertainty and model calibration on sewer system assessment
Authors: Korving H. , Clemens F.
Published: May 2018

Assessments of sewer performance are usually based on a single computation of CSO (combined sewer overflow) volumes using a time series of rainfall as system loads. A shortcoming of this method is that uncertainties in knowledge of sewer system dimensions are not taken into account. Moreover, sewer models are rarely calibrated. This paper presents the impacts of database errors and model calibration on return periods of calculated CSO volumes. The impact of uncertainties is illustrated with two examples. Variability of calculated CSO volumes is estimated using Monte Carlo simulations. The results show that calculated CSO volumes vary considerably due to database errors, especially uncertain dimensions of the catchment area. Furthermore, event-based calibration of a sewer model does not result in more reliable predictions because the calibrated parameters have low portability. However, it enables removal of database errors harmonising model predictions and ‘reality’.
Effect of climate changes on waterborne disease in The Netherlands
Authors: Schijven J.F. , de Roda Husman A.M.
Published: May 2018

Effects of climate change in The Netherlands in the 21st century on the microbiological quality of water for drinking water production and recreation were evaluated. The following was concluded: increased temperature leads to significant additional inactivation of enteric pathogens in surface waters with residence times of more than a month, but not in waters with residence times of up to ten days. Increased precipitation, runoff and storm water overflow lead to more peak concentrations of waterborne pathogens in surface water. Peak concentrations strongly determine the infection risk through drinking water consumption. Drought lowers and increased precipitation elevates groundwater tables, but an effect on the risk of groundwater contamination with waterborne pathogens is not clear. Climate effects are not noticeable near a groundwater well, where the groundwater table and flow rate are mainly determined by the pumping rate. Exposure of recreants to waterborne pathogens that can grow in the water is expected to increase due to increased recreation and increased growth opportunities of these pathogens. Due to warmer summers, pathogens, like amoeba, that have not caused problems up to date in The Netherlands, may now emerge in recreational waters.
An integrated modelling concept for immission-based management of sewer system, wastewater treatment plant and river
Authors: Erbe V. , Schütze M.
Published: May 2018

Today's planning standards deal with the individual urban drainage components (sewer system, wastewater treatment plant and receiving water) separately, i.e. they are often designed and operated as single components. As opposed to this, an integral handling considers the drainage components jointly. This novel approach allows a holistic and more sustainable planning of urban drainage systems. This paper presents an integrated modelling concept. The aim is to analyse fluxes through the total wastewater system and 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. All models of the different subsystems are based on the Activated Sludge Model (ASM) concept of IWA, including River Water Quality Model No. 1 (RWQM). Simulations can be done in truly parallel mode using the simulation environment SIMBA. The integrated modelling concept is applied to the river Dhuenn and the urban wastewater system of the municipality of Odenthal (Germany). An optimised operation of the system using RTC proves to be a very effective measure.
Modelling of different measures for improving removal in a stormwater pond
Authors: German J. , Jansons K. , Svensson G. , Karlsson D. , Gustafsson L.-G.
Published: May 2018

The effect of retrofitting an existing pond on removal efficiency and hydraulic performance was modelled using the commercial software Mike21 and compartmental modelling. The Mike21 model had previously been calibrated on the studied pond. Installation of baffles, the addition of culverts under a causeway and removal of an existing island were all studied as possible improvement measures in the pond. The subsequent effect on hydraulic performance and removal of suspended solids was then evaluated. Copper, cadmium, BOD, nitrogen and phosphorus removal were also investigated for that specific improvement measure showing the best results. Outcomes of this study reveal that all measures increase the removal efficiency of suspended solids. The hydraulic efficiency is improved for all cases, except for the case where the island is removed. Compartmental modelling was also used to evaluate hydraulic performance and facilitated a better understanding of the way each of the different measures affected the flow pattern and performance. It was concluded that the installation of baffles is the best of the studied measures resulting in a reduction in the annual load on the receiving lake by approximately 8,000 kg of suspended solids (25% reduction of the annual load), 2 kg of copper (10% reduction of the annual load) and 600 kg of BOD (10% reduction of the annual load).
Assessment of urban flooding by dual drainage simulation model RisUrSim
Authors: Schmitt T.G. , Thomas M. , Ettrich N.
Published: May 2018

The European research project in the EUREKA framework, RisUrSim is presented with its overall objective to develop an integrated planning tool to allow cost effective management for urban drainage systems. The project consortium consisted of industrial mathematics and water engineering research institutes, municipal drainage works as well as an insurance company. The paper relates to the regulatory background of European Standard EN 752 and the need of a more detailed methodology to simulate urban flooding. The analysis of urban flooding caused by surcharged sewers in urban drainage systems leads to the necessity of a dual drainage modeling. A detailed dual drainage simulation model is described based upon hydraulic flow routing procedures for surface flow and pipe flow. Special consideration is given to the interaction between surface and sewer flow during surcharge conditions in order to most accurately compute water levels above ground as a basis for further assessments of possible damage costs. The model application is presented for a small case study in terms of data needs, model verification and first simulation results.
The precautionary principle in times of intermingled uncertainty and risk: some regulatory complexities
Authors: van Asselt M.B.A. , Vos E.
Published: May 2018

This article explores the use of the precautionary principle in situations of intermingled uncertainty and risk. It analyses how the so-called uncertainty paradox works out by examining the Pfizer case. It reveals regulatory complexities that result from contradictions in precautionary thinking. In conclusion, a plea is made for embedment of uncertainty information, while stressing the need to rethink regulatory reform in the broader sense.
The precautionary principle and international conflict over domestic regulation: mitigating uncertainty and improving adaptive capacity
Authors: Oye K.A.
Published: May 2018

Disputes over invocation of precaution in the presence of uncertainty are building. This essay finds: (1) analysis of past WTO panel decisions and current EU-US regulatory conflicts suggests that appeals to scientific risk assessment will not resolve emerging conflicts; (2) Bayesian updating strategies, with commitments to modify policies as information emerges, may ameliorate conflicts over precaution in environmental and security affairs.
Stretched peer-review on unexpected results (GMOs)
Authors: Myhr A.I.
Published: May 2018

Science is the basis for governance of risk from genetically modified organisms (GMO), and it is also a primary source of legitimacy for policy decision. However, recently the publication of unexpected results has caused controversies and challenged the way in which science should be performed, be published in scientific journals, and how preliminary results should be communicated. These studies have subsequently, after being accepted for publication within the peer-review process of leading scientific journals, been thoroughly re-examined by many actors active within the GMO debate and thereby drawn extensive media coverage. The publicized charges that the research involved does not constitute significant evidence or represent bad science have in fact deflected attention away from the important questions related to ecological and health risks raised by the research. In this paper, I will argue that unexpected findings may represent “early warnings.” Although early warnings may not represent reality, such reports are necessary to inform other scientists and regulators, and should be followed up by further research to reveal the validity of the warnings. Furthermore, science that embraces robust, participatory and transparent approaches will be imperative in the future to reduce the present controversy surrounding GMO use and release.
Using the W&H integrated uncertainty analysis framework with non-initiated experts
Authors: Krayer von Krauss M.P. , Janssen P.H.M.
Published: May 2018

The W&H (Walker and Harremoës) integrated uncertainty analysis framework was put forward with the aim of providing a conceptual basis for the systematic treatment of uncertainty in model-based decision support activities such as policy analysis, integrated assessment and risk assessment. It provides a heuristic tool that can be applied in decision support exercises to classify and report the various dimensions of uncertainty. The intention is to stimulate better communication among analysts as well as between them and policymakers and stakeholders. The framework successfully articulates diverse scholarly understandings of ‘uncertainty’, ‘ignorance’, and ‘quality’ in science for policy. Nevertheless, experience with the W&H framework has revealed that many of the concepts put forward are relatively unfamiliar – and perhaps somewhat controversial – to experts practising decision support. Thus, efforts are required to communicate the W&H framework to experts in such a way that their knowledge of uncertainty is elicited adequately, without them being overly intimidated or confused by the novelty of the concepts presented to them. After introducing the W&H conceptual framework, this paper presents the methodology that was used in applying the W&H framework in expert elicitations on uncertainty in the risk assessment of genetically modified crops. Experiences with the use of this methodology are discussed and recommendations for further improvement are given.
The case of Lake Balaton: how can we exercise precaution?
Authors: Somlyódy L. , Honti M.
Published: May 2018

Balaton is the largest shallow lake in Central Europe and the most important recreational area in Hungary. Water balance of the lake is positive, while natural water level fluctuation has been significant. In 2000, an extreme drought period started. Until 2003, water level dropped about 70 cm (about 20% of the average depth). Public concern grew and the idea of water transfer from the Rába River was raised. To examine possible impacts a comprehensive study was prepared. The main question was whether water transfer was really needed and what criterion should be applied. For developing the methodology, three pillars were used: the potential climate change, the precautionary principle and the EU Water Framework Directive. The study covered impacts of the planned water transfer on the Rába–Balaton system in terms of changes of the water regime, water demands and quality, nutrient loads and ecosystems. The Thomas–Fiering ARMA model was used for characterizing monthly change of the natural water resources of the lake. A Monte Carlo generator was developed to analyze the occurrence of extreme events, uncertainties, possible climate change impacts and water level control strategies.
Uncertainty, imprecision, and the precautionary principle in climate change assessment
Authors: Borsuk M.E. , Tomassini L.
Published: May 2018

Statistical decision theory can provide useful support for climate change decisions made under conditions of uncertainty. However, the probability distributions used to calculate expected costs in decision theory are themselves subject to uncertainty, disagreement, or ambiguity in their specification. This imprecision can be described using sets of probability measures, from which upper and lower bounds on expectations can be calculated. However, many representations, or classes, of probability measures are possible. We describe six of the more useful classes and demonstrate how each may be used to represent climate change uncertainties. When expected costs are specified by bounds, rather than precise values, the conventional decision criterion of minimum expected cost is insufficient to reach a unique decision. Alternative criteria are required, and the criterion of minimum upper expected cost may be desirable because it is consistent with the precautionary principle. Using simple climate and economics models as an example, we determine the carbon dioxide emissions levels that have minimum upper expected cost for each of the selected classes. There can be wide differences in these emissions levels and their associated costs, emphasizing the need for care when selecting an appropriate class.
Physicochemical parameters influencing the formation of biofilms compared in mutant and wild-type cells of Pseudomonas chlororaphis O6
Authors: Anderson A.J. , Britt D.W. , Johnson J. , Narasimhan G. , Rodriguez A.
Published: May 2018

Bacteria colonize surfaces as heterogeneous structures called biofilms. Intercellular communication using acyl homoserine lactones has been implicated in biofilm formation in some systems. Here, we investigate cell structure in biofilms and associated physiochemical properties of wild type and quorum sensing mutants of Pseudomonas chlororaphis O6 (PcO6), a root-colonizing bacterium. The wild type strain generates multilayered biofilms under conditions where the quorum sensing mutant, deficient in the GacS sensor kinase, does not mature beyond a monolayer structure. However, this gacS mutant rapidly evolves to form a small colony variant (gacS-SCV) that again produces a multilayered biofilm structure although AHSL production is not restored to wild type level. Biofilms formed by the gacS-SCV (114±12°) mutant were the most hydrophobic displaying a higher average ethylene glycol contact angle than those formed by the wild type (28±7°) and gacS (18±6°). Tapping mode atomic force microscopy revealed elongated cell structure in both of the mutant biofilm cells. Digital pulsed force mode adhesion mapping showed that the average adhesion followed the order gacS>gacS-SCV, wild-type. Certain of these gacS mutant cells displayed strong interactions of the AFM tip with cell boundaries, the role of which in biofilm formation is currently under investigation.
Push-pull test evaluation of the in situ aerobic cometabolism of chlorinated ethenes by toluene-utilizing microorganisms
Authors: Azizian M.F. , Istok J.D. , Semprini L.
Published: May 2018

Single-well, push-pull tests were conducted in a contaminated aquifer to evaluate the ability of toluene-oxidizing microorganisms to cometabolize chlorinated aliphatic hydrocarbons (CAHs), such as trichloroethene (TCE). Test solutions were injected into the aquifer using a standard monitoring well, and then were transported under natural-gradient conditions. Transport tests demonstrated similar transport characteristics of the conservative tracer and the reactive solutes. Biostimulation tests were then performed by injecting a test solution containing dissolved toluene substrate, hydrogen peroxide, bromide, and nitrate in order to increase the biomass of toluene-utilizing microorganisms. Decreases in toluene concentration and the production of o-cresol as an intermediate oxidation product indicated the simulation of toluene-utilizing microorganisms containing an ortho-monooxygenase enzyme. Transformation tests demonstrated that indigenous microorganisms had the capability to transform the surrogate compounds (e.g. isobutene) and both cis-dichloroethene (cis-DCE) and trans-dichloroethene (trans-DCE). Isobutene was transformed to isobutene oxide, indicating transformation by a toluene ortho-monooxygenase, and both cis-DCE and trans-DCE were transformed. In a final test, the utilization of toluene, and the transformation of isobutene, cis-DCE, and trans-DCE were all inhibited in the presence of 1-butyne, a known inhibitor of the toluene ortho-monooxygenase enzyme. The method assessed the activity of attached microorganisms under in situ conditions of bioremediation.
Visualization and characterization of dynamic patterns of flow, growth and activity of biofilms growing in porous media
Authors: Sharp R.R. , Stoodley P. , Adgie M. , Gerlach R. , Cunningham A.
Published: May 2018

Using a mesoscale porous media flat plate reactor we utilized a naturally bioluminescent biofilm (V. fischeri) and dye studies to obtain valuable information on the interactions between biofilms and reactive flow in porous media. The growth and development of the V. fischeri biofilm in a porous media geometry was studied using digital time lapse images of the bioluminescent signal given off by the developing biofilm. The effect of biofilm development on porous media hydrodynamics was examined using dye tracer studies and image analysis. The natural bioluminescence of the V. fischeri allowed real-time, in-situ study of biofilm development in porous media, without destruction of the biofilm. Dye studies and image analysis enabled the study of effects of biofilm accumulation on porous media hydraulics, with comparisons to plug flow and completely mixed systems with varying degrees of biofilm accumulation. The real-time nature of the study permitted us to visualize dynamic flow channel formation within the biofilm/porous media system. In addition, the sensitivity of the V. fischeri biofilm to dissolved oxygen allowed us to capture real-time images of reactive transport within the system. This work is the first meso-scale visualization of the interactions between biofilm and flow in porous media.
Biofilm reactor technology for low temperature anaerobic waste treatment: microbiology and process characteristics
Authors: McHugh S. , Collins G. , Mahony T. , O'Flaherty V.
Published: May 2018

The microbial composition, methanogenic activity and architecture of particulate and fixed biofilms within four anaerobic hybrid reactors, R1–R4, operating at psychrophilic temperatures were investigated. The reactors treated low-strength (1 g COD l−1; R1) and high-strength (10 g COD l−1; R2–R4) wastewaters from the food-processing sector (R1, R2 – whey; R3 – sucrose; R4 – volatile fatty acids). Successful start-up and long-term psychrophilic operation was observed for all four reactors, with COD removal efficiencies of 80–99% achieved at 12–20 °C at organic loading rates of 1.3–20 kg COD m−3 d−1. The formation and maintenance of a well-settling granular sludge bed and an attached biofilm were shown to occur under psychrophilic conditions, an important consideration for the successful implementation of low temperature biofilm reactor technology. Culture-independent molecular techniques (terminal restriction fragment length polymorphism, clone library analysis and 16S rRNA gene sequencing) revealed that microbial population structure could be a key factor in reactor performance, with changes in the community structure of the three high-strength reactors preceding granular instability and a subsequent decline in COD removal efficiency. Biomonitoring of microbial population structure and dynamics within anaerobic reactors may, therefore, allow for the early recognition of potential operational problems.
Microautoradiography: recent advances within the studies of the ecophysiology of bacteria in biofilms
Authors: Nielsen P.H. , Nielsen J.L.
Published: May 2018

Microautoradiography (MAR) is a technique that allows the direct identification of active microorganisms and of their metabolic capabilities without prior enrichment or cultivation. Today, this technique is probably the only one that allows an in-depth investigation of the ecophysiology of uncultivated bacteria under their natural conditions, and it possesses, therefore, alone or in combination with other in situ techniques, a great potential to be used in comprehensive studies of biofilms and other ecosystems. Here, we present a brief description of the microautoradiographic technique, and recent examples of the type of information that can be obtained using MAR in combination with FISH or with other methods when investigating biofilm processes. Also, some limitations of the technique are discussed.
Effect of nucleic acid stain Syto9 on nascent biofilm architecture of Acinetobacter sp. BD413
Authors: GrayMerod R. , Hendrickx L. , Mueller L.N. , Xavier J.B. , Wuertz S.
Published: May 2018

Flow cells were utilized to determine the effects of repetitive Syto9 staining on developing Acinetobacter sp. BD413 biofilm and to identify features describing reproducible biofilm architecture at 63× magnification. Syto9 is a general nucleic acid stain employed to visualize the entire microbial population of the biofilm and a component in the LIVE/DEAD® BacLight™ Bacterial Viability kits. CLSM images were quantified with the biofilm analysis software PHLIP to calculate six commonly used biofilm architecture characteristics. The characteristics biovolume and mean thickness were most reproducible when biofilms were grown in separate flow cells under controlled conditions, while roughness, porosity, total spreading and surface area to biovolume ratio exhibited inherent variability. Biovolume was more variable in separate flow cells than in channels of the same flow cell. However, even biofilms grown in channels of the same flow cell did not generate reproducible architectures based on the six characteristics. Results suggest difficulties in differentiating the effect of changes due to treatment from the natural variability of architecture development at the cellular level. Despite this high variability, biofilms only stained once developed into thicker structures containing more biomass than biofilms stained multiple times, suggesting that repeated staining with Syto9 affects architecture development. The application of Syto9 to monitor developing biofilms is not recommended.
Groundwater and human development: challenges and opportunities in livelihoods and environment
Authors: Shah T.
Published: May 2018

At less than 1,000 km3/year, the world's annual use of groundwater is 1.5% of renewable water resource but contributes a lion's share of water-induced human welfare. Global groundwater use however has increased manifold in the past 50 years; and the human race has never had to manage groundwater use on such a large scale. Sustaining the massive welfare gains groundwater development has created without ruining the resource is a key water challenge facing the world today. In exploring this challenge, we have focused a good deal on conditions of resource occurrence but less so on resource use. I offer a typology of five groundwater demand systems as Groundwater Socio-ecologies (GwSE), each embodying a unique pattern of interactions between socio-economic and ecological variables, and each facing a distinct groundwater governance challenge. During the past century, a growing corpus of experiential knowledge has accumulated in the industrialized world on managing groundwater in various uses and contexts. A daunting global groundwater issue today is to apply this knowledge intelligently to by far the more formidable challenge that has arisen in developing regions of Asia and Africa, where groundwater irrigation has evolved into a colossal anarchy supporting billions of livelihoods but threatening the resource itself.
Workshop 3 (synthesis): recycling and water utilities – shared characteristics of well performing and ‘turnaround’ utilities and the reform of poorly performing utilities
Authors: Rahman A. , Otterpohl R.
Published: May 2018

New approaches and technologies are required to deal with extremely unsatisfactory sanitation conditions, which give rise to serious health problems. Nutrient loads reaching recipients also pose threats to ecosystems.
Effect of soil and a nonionic surfactant on BTE-oX and MTBE biodegradation kinetics
Authors: Acuna-Askar K. , Gracia-Lozano M.V. , Villarreal-Chiu J.F. , Marmolejo J.G. , Garza-Gonzalez M.T. , Chavez-Gomez B.
Published: May 2018

The biodegradation kinetics of BTE-oX and MTBE, mixed all together, in the presence of 905mg/L VSS of BTEX-acclimated biomass was evaluated. Effects of soil and Tergitol NP-10 in aqueous samples on substrate biodegradation rates were also evaluated. Biodegradation kinetics was evaluated for 36 hours, every 6 hours. MTBE biodegradation followed a first-order one-phase kinetic model in all samples, whereas benzene, toluene and ethylbenzene biodegradation followed a first-order two-phase kinetic model in all samples. O-xylene biodegradation followed a first-order two-phase kinetic model in the presence of biomass only. Interestingly, o-xylene biodegradation was able to switch to a first-order one-phase kinetic model when either soil or soil and Tergitol NP-10 were added. The presence of soil in aqueous samples retarded benzene, toluene and ethylbenzene removal rates. O-xylene and MTBE removal rates were enhanced by soil. The addition of Tergitol NP-10 to aqueous samples containing soil had a positive effect on substrate removal rate in all samples. Substrate percent removals ranged 77–99.8% for benzene, toluene and ethylbenzene. O-xylene and MTBE percent removals ranged 50.1–65.3% and 9.9–43.0%, respectively.
Workshop 4 (synthesis): green/blue water management options for crop production
Authors: Rockström J. , Gordon L.
Published: May 2018

There is a huge untapped potential for increases in crop yields from green water flows. By better land use management of the whole drainage basin we can get more out of green water without compromising blue water flows
Green–blue water system innovations for upgrading of smallholder farming systems – a policy framework for development
Authors: Hatibu N. , Rockström J.
Published: May 2018

Rainfed agriculture and other depletion of water by green flows have as yet an untapped potential for improving livelihoods in semi-arid areas through income and food security. A vivid evidence of this is seen in the fact that, although working full time on food production, majority of smallholder farmers are frequently affected by shortage of food or famines. At the same time enough examples exist to show that productivity of labor, water and land under rainfed farming can be doubled or even trebled through proper land management and improved agronomic inputs supported by modest investments to reduce impacts of dry spells. However, these shining examples remain small ‘islands of success’ across the entire semi-arid areas. Farmers have not adopted these systems due to poor ratio of benefit to costs brought about by inadequate development or complete lack of food trade among the rural areas. This paper argues that there is a need for policy, strategic and programmatic frameworks which facilitate integrated management of land, water and markets. For this kind of strategy to work, a local market for food should be ensured to absorb at competitive prices the surplus produced by farmers in years of good rains. This will promote wealth creation and asset building among the poor in semi-arid areas. A food-exchange “futures” mechanism based on the principle of virtual water trade is proposed as a basis for achieving this objective.
Water and the other three revolutions needed to end rural poverty
Authors: Polak P.
Published: May 2018

Eight hundred million of the current 1.1 billion people who earn less than a dollar-a-day live in rural areas in developing countries. Since more than 550 million of them earn their living from agriculture, poverty eradication depends on increasing their income from farming. The millennium goals for hunger and poverty in the semi-arid tropics will not be met without four simultaneous revolutions. A revolution in water is needed to develop and mass disseminate a whole range of new affordable small plot irrigation technology. A revolution in agriculture is required to enable smallholders to produce a variety of high value marketable labor intensive cash crops. A revolution in markets is needed to open access to inputs and to profitable markets for their high value crops, incorporating effective strategies for aggregation, quality control, and decentralized added value processing. Finally, a revolution in design based on the ruthless pursuit of affordability is needed to support the other three revolutions. This paper describes the rapidly growing micro-irrigation revolution exemplified by the $250 million in new net annual income now being earned by Treadle Pump farmers, and outlines the key features of the other three revolutions required to meet millennium poverty goals.
Intensive groundwater use: a silent revolution that cannot be ignored
Authors: Llamas M.R. , Martínez-Santos P.
Published: May 2018

Over the last decades, agriculture in arid and semi-arid countries has experienced a true “silent revolution” of intensive groundwater use. Millions of independent farmers worldwide have chosen to become increasingly dependent on the reliability of groundwater resources, and as a result their countries have reaped abundant social and economic benefits. Data from several countries shows that groundwater irrigation presents a much greater efficiency, than surface water irrigation systems, thus contributing to fulfil the motto of “more crops and jobs per drop”. If this situation is confirmed globally, the usual world water visions have to be reviewed. However, the “silent revolution” has been carried out with scarce control on the part of governmental water agencies, and thus a series of unwanted effects have developed in certain places. While these by no means justify the pervasive “hydromyths” and obsolete paradigms that voice the frailty of groundwater, appropriate management of groundwater resources remains a worldwide challenge. This paper provides an overview of these issues, and concludes with the necessity there is to educate all levels of society on the importance of groundwater and to create bottom-up user associations to manage aquifers as common pool resources.
Significance of bacteria associated with invertebrates in drinking water distribution networks
Authors: Wolmarans E. , Preez H.H. du , Wet C.M.E. de , Venter S.N.
Published: May 2018

The implication of invertebrates found in drinking water distribution networks to public health is of concern to water utilities. Previous studies have shown that the bacteria associated with the invertebrates could be potentially pathogenic to humans. This study investigated the level and identity of bacteria commonly associated with invertebrates collected from the drinking water treatment systems as well as from the main pipelines leaving the treatment works. On all sampling occasions bacteria were isolated from the invertebrate samples collected. The highest bacterial counts were observed for the samples taken before filtration as was expected. There were, however, indications that optimal removal of invertebrates from water did not always occur. During the investigation, 116 colonies were sampled for further identification. The isolates represent several bacterial genera and species that are pathogenic or opportunistic pathogens of humans. Diarrhoea, meningitis, septicaemia and skin infections are among the diseases associated with these organisms. The estimated number of bacteria that could be associated with a single invertebrate (as based on average invertebrate numbers) could range from 10 to 4000 bacteria per organism. It can, therefore, be concluded that bacteria associated with invertebrates might under the worst case scenario pose a potential health risk to water users. In the light of the above findings it is clear that invertebrates in drinking water should be controlled at levels as low as technically and economically feasible.
Application of a virological tracer method for the assessment of pathogen removal by physicochemical treatment and chemical disinfection
Authors: Wang X.C. , Qiu F.G. , Xue X.P. , Lu X.
Published: May 2018

Coxsackie B3 (CoxB3) virus was used as a virological tracer for an assessment of the efficiency of pathogen removal by several typical physicochemical treatment and chemical disinfection processes, such as coagulation-filtration, ultra-filtration, and disinfection using chlorine and ozone, with regard to the pathogenic quality of the treated domestic wastewater for reuse purposes. The CoxB3 virus was seeded to sterilized secondary effluent to make a raw water of known pathogenic level. After applying the raw water to each treatment or disinfection process, the residual virus in the finished water was concentrated, and virus assay was carried out by the Tissue Culture Infectious Dose technique. TCID50 was used as an indicative parameter of CoxB3 virus in the raw and treated water. Parallel experiments were also conducted to evaluate the effectiveness of each process for the removal of coliform bacteria. It was noticed from the experiment that both coagulation-filtration and ultrafiltration could achieve substantial removal of TCID50 at about the same level (2-log removal). However, the effect of the two processes on the removal of coliform bacteria was much different: 2-log removal by coagulation-filtration and 4 to 5-log removal by ultrafiltration. The TCID50 removal correlates more closely with the removal of turbidity than that of coliform bacteria. Chlorine was found to be effective in coliform removal but almost had no effect on TCID50. As ozone was applied, a high removal of both coliform bacteria and TCID50 could be obtained.
Biochemical pathway and degradation of phthalate ester isomers by bacteria
Authors: Gu J.-D. , Li J. , Wang Y.
Published: May 2018

Degradation of dimethyl isophthalate (DMI) and dimethyl phthalate ester (DMPE) was investigated using microorganisms isolated from mangrove sediment of Hong Kong Mai Po Nature Reserve. One enrichment culture was capable of utilizing DMI as the sole source of carbon and energy, but none of the bacteria in the enrichment culture was capable of degrading DMI alone. In co-culture of two bacteria, degradation was observed proceeding through monomethyl isophthalate (MMI) ester and isophthalic acid (IPA) before the aromatic ring opening. Using DMI as the sole carbon and energy source, Klebsiella oxytoca Sc and Methylobacterium mesophilicum Sr degraded DMI through the biochemical cooperation. The initial hydrolytic reaction of the ester bond was by K. oxytoca Sc and the next step of transformation was by M. mesophilicum Sr, and IPA was degraded by both of them. In another investigation, a novel bacterium, strain MPsc, was isolated for degradation of dimethyl phthalate ester (DMPE) also from the mangrove sediment. On the basis of phenotypic, biochemical and 16S rDNA gene sequence analyses, the strain MPsc should be considered as a new bacterium at the genus level (8% differences). This strain, together with a Rhodococcus zopfii isolated from the same mangrove sediment, was able to degrade DMPE aerobically. The consortium consisting of the two species degraded 450mg/l DMPE within 3 days as the sole source of carbon and energy, but none of the individual species alone was able to transform DMPE. Furthermore, the biochemical degradation pathway proceeded through monomethyl phthalate (MMP), phthalic acid (PA) and then protocatechuate before aromatic ring cleavage. Our results suggest that degradation of complex organic compounds including DMI and DMPE may be carried out by several members of microorganisms working together in the natural environments.
Constructed wetlands in UK urban surface drainage systems
Authors: Shutes B. , Ellis J.B. , Revitt D.M. , Scholes L.N.L.
Published: May 2018

This paper presents the outcome of an inventory of planted wetland systems in the UK which are classified according to land use type and are all examples of sustainable drainage systems. The introduction of constructed wetlands to treat surface runoff essentially followed a 1997 Environment Agency for England and Wales report advocating the use of “soft engineered” facilities including wetlands in the context of sustainable development and Agenda 21. Subsequently published reports by the UK Construction Industry Research and Information Association (CIRIA) have promoted the potential benefits to both developer and the community of adopting constructed wetlands and other vegetated systems as a sustainable drainage approach. In addition, the UK Environment Agency and Highways Agency (HA) have recently published their own design criteria and requirements for vegetative control and treatment of road runoff. A case study of the design and performance of a constructed wetland system for the treatment of road runoff is discussed. The performance of these systems will be assessed in terms of their design criteria, runoff loadings as well as vegetation and structure maintenance procedures. The differing design approaches in guidance documents published in the UK by the Environment Agency, CIRIA and HA will also be evaluated.
Analysis of scenarios for wastewater and urban drainage systems in Brazil based on an integrated modeling approach
Authors: Soares S.R.A. , Parkinson J. , Bernardes R.S.
Published: May 2018

Brazil is currently facing widespread problems in the urban environment associated with inadequate wastewater and urban drainage systems, particularly for low-income communities. These problems are promoted by the rapid and often unplanned urbanization process in developing cities and are compounded by a lack of funding, absence of planning, ineffective institutional arrangements, and inappropriate policies to provide the framework for integrated wastewater and stormwater management. Because planning for the provision of wastewater and urban drainage systems is a complex task, an integrated-modeling approach is proposed to provide a practical methodology for sanitation and urban drainage planning in Brazilian cities. In the model development, as well as technical aspects, other aspects related to institutional, financial, socio-economic, environmental and public health issues were also taken into account.