bluuebunny/crossref_metadata_2025 huggingface dataset:
Economic benefit from irrigation of cotton and corn with treated wastewater
Authors: Tsadilas C.D. , Vakalis P.S.
Published: May 2018

The effect of irrigation with treated municipal wastewater on the agricultural income from cotton and corn crops was studied by a three-year field experiment (1995-1997), carried out within the wastewater treatment plant (WWTP) of the city of Larissa, central Greece. The experimental design for both crops was randomised complete blocks with five treatments (M- control-irrigation with fresh water, W-irrigation with wastewater and no mineral fertilization, MF- irrigation with fresh water and complete mineral fertilization, WSF- irrigation with wastewater and reduced mineral fertilization, WTF- irrigation with wastewater and complete mineral fertilization). Each treatment was replicated four times. The agricultural income was assessed using the yield of the crops and the economic data of the area. The results showed that in the case of corn, the treatment WTF gave the highest agricultural income. The treatments W and WSF gave higher agricultural income compared to the control but was not significantly different compared to the treatment MF. In the case of cotton, all the treatments included wastewater use, increased significantly the agricultural income in comparison to the control, but at similar level as the treatment MF did. From the data of this study, it is concluded that treated wastewater can be used for irrigation of corn and cotton, saving fresh water and mineral fertilizers and obtaining the same or better economic results.
The long-term performance of Soil Aquifer Treatment (SAT) for effluent reuse
Authors: Idelovitch E. , Icekson-Tal N. , Avraham O. , Michail M.
Published: May 2018

An innovative scheme of groundwater recharge for wastewater effluent reuse has been practiced on a large scale in the Dan Region Project in Israel since 1977. The system, referred to as SAT (for Soil Aquifer Treatment), provides advanced treatment prior to effluent reuse for unrestricted irrigation. A major study recently carried out consisted of a comprehensive analysis of the water quality data available in the recharged effluent (before SAT), as well as in observation wells and recovery wells (after SAT). The results obtained with respect to suspended solids, organics and nutrients (nitrogen compounds and phosphorus) are presented and discussed. The main processes occurring in the soil-aquifer system, which are responsible for the removal of the above contaminants are filtration through the upper soil layer, organic matter biodegradation and adsorption, ammonia adsorption and biological nitirification-denitrification, and chemical precipitation and adsorption of phosphorus. The findings of the study have provided valuable information on the above processes and their interaction, and have demonstrated that the SAT system should be considered an attractive method for effluent reuse in areas where hydrogeological conditions are suitable for groundwater recharge via spreading basins.
Methods for estimating water network rehabilitation needs
Authors: Sægrov S. , König A. , Mattick A. , Milina J. , Röstum J. , Selseth I.
Published: May 2018

This paper comprises a brief overview of some of the computer-based methods for water network rehabilitation planning, which are currently applied in Norway. Examples from some Norwegian cities using tools for estimation of long-term rehabilitation needs, network serviceability, as well as methods for prediction of water network failure frequency and failure distribution, are presented. These tools have been shown to give important support to the planning of future investments on water networks and the selection of rehabilitation candidates.
Aggressive flushing for discolouration event mitigation in water distribution networks
Authors: Boxall J.B. , Skipworth P.J. , Saul A.J.
Published: May 2018

Discolouration is one of the biggest causes of customer complaint associated with potable water. The flushing of systems has been widely identified as an appropriate pro-active means of removing material from distribution networks and hence controlling discolouration. Such flushing involves creating aggressive hydraulic forces within the network such that the materials that contribute to discolouration are mobilised and removed. Understanding of the causes and mechanisms leading to discolouration are poor. Previous work has been presented on the characterisation of material and particles collected at hydrants during flushing trials in the UK. From this data it was hypothesised that the materials causing discolouration originated from cohesive layers on pipe walls, and that once disturbed the material is maintained as a permanent suspension even under the most quiescent of networks conditions. The work presented in this paper attempts to validate the hypothesis that the discolouration materials originate from cohesive layers, and investigate the nature and variability of such layers within live distribution systems.

The study involved the aggressive flushing of a long discrete length of cast iron pipe with known discolouration problems. The results showed a progressive generation of material over the length of the pipe, confirming that the material originated from a uniformly distributed cohesive source. This was followed by a sequence of flushing operations for the systematic cleaning of a complex network area, encompassing a mixture of pipe materials and ages. All measured turbidity traces showed exponential decay with time. Such exponential decay may be predicted by a model based on a change in layer strength with degree of erosion. Hydraulic forces appear to be a key factor governing the availability and mobilisation of material. Iron is the dominant material mobilised from all the pipes. There is no direct trend between the amount or the composition of the material mobilised from the different pipes.
Dependency of bulk chlorine decay rates on flow velocity in water distribution networks
Authors: Menaia J. , Coelho S.T. , Lopes A. , Fonte E. , Palma J.
Published: May 2018

Understanding chlorine residual decay kinetics and the factors that influence them are essential for such current tasks as siting chlorination facilities, dosage optimisation, choice of sampling locations and frequencies, and general design and operational control of drinking water networks, increasingly accomplished with the help of simulation models.

Available constants for bulk chlorine decay are typically determined under static conditions. However, as for all fast reactions in water flows, chlorine consumption rates in drinking water pipes may be influenced by the existing mixing regimes, a function of flow turbulence, which is primarily controlled by flow velocity and pipe diameter.

Flow velocities vary greatly in space and time in water transmission and distribution systems; pipe diameters are seldom uniform. Although both variables are readily available in the currently available network analysis simulators that implement chlorine models, such variations are not accounted for. Instead, a single preset decay rate constant is generally used for describing chlorine residual consumption throughout an entire system.

In addition to highlighting how negligible PVC pipe wall chlorine consumption is, as such, this paper presents experimental evidence of a significant correlation between pipe flow velocity and bulk chlorine decay rates, and proposes a simple but effective approach to implement this dependency in current simulators.
Prevention of bacterial growth in a long-distance water supply system: control of disinfection capacity
Authors: Fischeder R. , Weber W.
Published: May 2018

Drinking water has to be wholesome and clean, free from chemical and, most of all, microbiological contaminants. The German Landeswasserversorgung (LW), a long distance water supplier, uses surface water and water influenced by surface water as well as groundwater for drinking water production. A combination of several treatment steps including flocculation, sedimentation, ozonation, in-line filtration and, finally, disinfection with chlorine dioxide guarantees a drinking water of perfect quality. Since the water transport through several main and subsidiary pipes of an overall length of about 500 kilometres can take up to four days, the disinfection capacity must be sufficient to prevent bacterial growth. Measurement of the redox potential in addition to measurement of chlorine dioxide concentrations has proved to be a helpful parameter for the surveillance of the disinfection capacity. Many years of experience show that keeping the redox potential above a level of 650 mV guarantees the prevention of bacterial growth and an efficient disinfection.
Pressure-driven modelling of water distribution systems
Authors: Tanyimboh T. , Tahar B. , Templeman A.
Published: May 2018

This paper presents a novel method to model water distribution systems (WDS) with insufficient pressure. Methods for the prediction of the performance of a WDS with pressure deficiencies are reviewed. The influence of imposed relationships between nodal heads and outflows is assessed and numerical results are given. A Newton-Raphson technique plus line search is employed for solving the governing equations. It is demonstrated that the approach offers superior results for the hydraulic performance of networks under abnormal operating conditions compared to demand-driven analysis-based models.
Vacuum membrane distillation for seawater desalination: could it compete with reverse osmosis?
Authors: Wirth D. , Cabassud C.
Published: May 2018

This work addresses the potentialities of vacuum membrane distillation (VMD) using hollow fibre membranes for seawater desalination. Experiments were carried out with a synthetic salty water containing a concentration of NaCl from 0 up to 300 g/L. A Microza (Pall) hollow fibre module was used. Experimental results show that, for this module, concentration polarisation and heat transfer limitations are not significant and do not modify the permeate flux. This is a great advantage over reverse osmosis (RO). Energy consumption was then studied using computations based on modelling. Two different industrial plants were considered: the first one consisted of hollow fibre modules arranged in series and operated in a single-pass. The second one was designed for a discontinuous operation using a circulation loop. Computations clearly show the interest (low energy consumption) of VMD for seawater desalination in comparison with RO.
Evaluation of biologic and non-biologic methods for assessing virus removal by and integrity of high pressure membrane systems
Authors: Kitis M. , Lozier J.C. , Kim J.H. , Mi B. , Mariñas B.J.
Published: May 2018

This paper describes pilot-scale studies that examined three integrity test methods for: (1) quantifying virus removal by nanofiltration (NF) and reverse osmosis (RO) membrane systems when arranged in single element unit and two-stage system configurations, and (2) determining change in virus removal capability of such systems when subject to different types of membrane/o-ring compromisation and fouling. The three methods evaluated included one biologic type (MS-2 phage), that has been employed previously; and two, new non-biologic types (24-nanometre polystyrene fluorescent dyed microspheres and fluorescent Rhodamine WT [R-WT] dye, molecular mass 496 daltons). All three surrogates were employed in a manner intended to show a minimum of 4-logs removal by the NF and RO membranes selected for test. Methods of compromisation included a pinhole induced through one membrane leaf in the spiral wound NF/RO element, and both cracking of and removal of sections from one of the permeate tube o-rings. Testing was conducted on two source waters, representing brackish surface water and effluent categories: a microfiltered secondary effluent and a river water. The river water is characterized by low to moderate TDS and high TOC and was treated with conventional alum coagulation, flocculation, sedimentation and granular media filtration for subsequent membrane processing.
Ultrafiltration-nanofiltration for removal of hydrogen sulfide, elemental sulfur, and sulfate from a municipal groundwater
Authors: Reiss C.R. , Talton E. , Schuck R.
Published: May 2018

The City of Delphos, Ohio implemented a study to determine the most effective method of reducing total dissolved solids (TDS), sulfate, and hardness. A desktop and pilot study determined that dissolved oxygen was oxidizing hydrogen sulfide gas in the wellfield and forming element sulfur manifesting itself via high turbidity levels (>20 NTU). While chemical resolubilization via sodium metabisulfite was able to reduce turbidity by +90%, filtration was still required prior to nanofiltration (NF) to mitigate NF plugging. Zenon ultrafiltration effectively reduced feed water turbidity from over 20 NTU to less than 0.15 NTU. The resulting feed water to the NF system eliminated NF fouling from particle plugging. NF was effective for reducing inorganic ions including hardness and TDS.
Research on AirFlush®: distribution of water and air in tubular and capillary membrane modules
Authors: Verberk J. , van Dijk H.
Published: May 2018

Dead-end ultrafiltration has proved itself as a technique for reclamation of backwash water of sand filters and as a pretreatment step before spiral wound reverse osmosis. A direct result of dead-end filtration is a flux decrease in time caused by the accumulation of material in the membrane pores and on the membrane surface. Different cleaning techniques are used to remove this accumulated material. Recently a new technique has been introduced, the AirFlush®. This technique makes use of air to create higher turbulence as compared to a water flush. At Delft University of Technology in co-operation with X-flow and Norit Membrane Technology research has been started into the fundamentals of the combined air and water flush. As in many industrial processes, an equal division of water and air over an installation is very important. To check the distribution of water and air over the cross-sectional area of tubular and capillary membrane modules two different test installations have been built. The results from the experiments show that for tubular membrane modules the water and air distribution over the cross-sectional area of the module is not always equally divided. Improvements have to be obtained by a better air distribution system. For capillary membrane modules the distribution of water and air over the cross-sectional area is more equally divided. The results from the experiments are discussed taking into account the theory of two-phase flow. It is shown that from the theory of two-phase flow the good distribution for the capillary membrane module can be explained by the large frictional pressure drop compared to the hydrostatic pressure drop.
Urban metabolic system of water for the 21st century
Authors: Tambo N.
Published: May 2018

Since human activity is about to outgrow the natural capacity, thus becoming a prominent affector to the environment, an urban/regional water system that minimizes influence on the environment, but at the same time, satisfies the human needs must be considered. This is necessary to keep well being urban/industrial areas side-by-side with the external nature. To address this problem, new systems of water and wastewater treatment as well as new methods of water utilization are coming up. The considerations and issues related to the planning and design of such water systems are discussed in this paper.
Campylobacter in waterborne epidemics in Finland
Authors: Hänninen M.-L. , Kärenlampi R.
Published: May 2018

The sources for drinking water in Finland are surface water, groundwater or artificially recharged groundwater. There are approximately 1400 groundwater plants in Finland that are microbiologically at a high risk level because in most cases they do not use any disinfection treatment. Campylobacter jejuni has caused waterborne epidemics in several countries. Since the middle of the 1980s, C. jejuni has been identified as the causative agent in several waterborne outbreaks in Finland. Between 1998 and 2001, C. jejuni or C. upsaliensis caused seven reported waterborne epidemics. In these epidemics approximately 4000 people acquired the illness. Most of the outbreaks occurred in July, August , September or October. In four of them source water and net water samples were analysed for total coliforms or fecal coliforms, E. coli and campylobacters. We showed that large volumes of water samples in studies of indicator organisms (up to 5000 ml) and campylobacters (4000–20,000 ml) increased the possibility to identify faecal contamination and to detect the causative agent from suspected sources.
Determination of naturally occurring noroviruses in coastal seawater by alkaline elution after acid rinse using negatively charged membrane
Authors: Katayama H. , Tanaka A. , Otaki M. , Ohgaki S.
Published: May 2018

A new procedure for concentrating viruses from seawater using a negatively charged membrane eluting with alkaline solution (NaOH, pH 10.5) after acid rinse (H2SO4, pH 3.0) was applied to determine naturally occurring enteric viruses in seawater in Tokyo bay. The levels of total coliforms and fecal coliforms ranged from 40 to 68000 (cfu/100ml) and from 2 to 32000 (cfu/100ml), respectively. The F-specific phages were not detected from 5 ml of 53 samples out of 61 tested. The levels of indicator microbes were not found to be related to the tide in Tokyo bay. Enteroviruses were not detected by cell culture RTÐPCR, but detected by direct RTÐPCR from approximately 10% of the samples. Noroviruses were found positive from approx. 31% of the winter samples (n=29), whereas only 3% from the summer samples (n=32). These results of direct RTÐPCR were equivalent to determination of Norwalk viruses occuring in 50 ml of seawater. These results suggested that the levels of noroviruses in Tokyo bay were higher in winter than those of enteroviruses The virus concentration method used was proved to be useful for determination of naturally occurring viruses in seawater, especially when applied prior to PCR detection of nonculturable viruses.
Drinking water pipe biofilm: present knowledge, concepts and significance
Authors: Menaia J. , Mesquita E.
Published: May 2018

Biofilms invariably colonize drinking water distribution systems with intensities and patterns governed by the habitat's environment. Water temperature and flow dynamics, nutrient availability, disinfectant residual and pipe material determine their development, structure and composition. Drinking water pipe biofilms control microbial regrowth and are a possible source of pathogens. However, these are possibly released at levels that do not generally impart hazards to healthy drinking water consumers. A deeper understanding of drinking water biofilms microbial ecology must be achieved before this issue can be adequately assessed.
Droughts, risk management and reliability
Authors: Cubillo F.
Published: May 2018

In many places of the world, droughts become normal but not frequent meteorological conditions. Some times, extended drought conditions are the origin of scarcity scenarios in water supply systems. These scarcity scenarios, many times produced by causes not related to climate, are real threats to the reliability of water systems and must be prevented and managed. Those scarcity episodes have been approached in different ways and there are no clear criteria to apply based on risk management techniques to assess the risk of scarcity or to manage them within a context of efficiency and sustainable use of resources. This paper shows some ideas and guidelines on how to integrate drought planning and operation in an efficient and sustainable water supply management.
Low-flow devices in Spain: how efficient are they in fact? An accurate way of calculation
Authors: Cobacho R. , Arregui F. , Gascó;n L. , Cabrera E.
Published: May 2018

After introducing the indirect evaluation of urban water demand, which has been sometimes performed, this paper focus the attention on two complementary methods to overcome the accuracy problems on the planning process of water conservation programs: a detailed measurement of water consumption, reaching the identification and assessment of end uses of water, and the lab tests of water use devices. An application of both methods on a small Spanish town is presented as a case study.
Saragossa, 50 examples of efficient water use in the city
Authors: Viñuales Edo V. , Fernández Soler M.
Published: May 2018

The water saving project, Saragossa, water saving city. 50 Good Practices aims to resolve the problems of water scarcity with a different approach which is cheaper, more ecological and free from social conflicts: increasing the efficiency of its use. It seeks to provide a model to be imitated by the more than 9,000 Spanish towns which waste over 1,500 hm3 of water per year.

In 1997 a collective challenge was put forward: to save 1 billion litres of water in one year. In fact 1,176 billion litres was saved, 5.6% of domestic consumption. 50 Good Practices in efficient water use are currently being worked on. As we have demonstrated in the project, technological change is produced via imitation. The Hospital Royo Villanova, with a consumption of 382 litres per bed per day, is one such example to imitate; this is one of the best ratios in the world. Today Saragossa has one of the lowest ratios of domestic consumption per inhabitant per day in Spain: 96 litres.
Effect of multiple GAC reactivations on disinfection byproduct precursor removal
Authors: Metz D.H. , DeMarco J. , Pohlman R. , Cannon F.S. , Moore B.C.
Published: May 2018

The objective of this study was to compare the adsorption capabilities of the virgin carbon to the twelve and five times reactivated granular activated carbon (GAC). From a water treatment plant operator's perspective, there were very few practical differences in adsorption among the carbons tested for total organic carbon (TOC) and disinfection byproduct (DBP) precursors. However, some overall trends were observed. The GAC that was regenerated 5 times (R5) generally showed greater DBP precursor adsorption than the other GACs especially at the beginning of the runs. In some cases the carbon that was reactivated 12/13 times (R12 and R13) adsorbed slightly less DBP precursors than the other GACs especially in the latter part of the runs. The virgin (V) carbon performed better than the other GACs relative to DBP precursor removal in the latter part of the runs.
Practical application of a combined treatment process for removal of recalcitrant NOM - alum and PAC
Authors: Fabris R. , Chow C.W.K. , Drikas M.
Published: May 2018

Three different powdered activated carbons were applied in combination with aluminium sulphate to treat a high dissolved organic carbon (DOC) source water with a focus on improving natural organic matter removal. Treated water quality was analysed using absorbance at 254 nm, DOC, trihalomethane formation potential (THM-FP), rapid fractionation, C13 NMR and molecular weight distribution by high performance size exclusion chromatography. Carbon C and B offered equivalent DOC removal but carbon C was considered superior as treated water THM-FP was reduced. It is postulated that an organic fraction around 1000 Daltons is responsible for differences in THM-FP shown in the treated waters.
The effects of changing NOM composition and characteristics on coagulation performance, optimisation and control
Authors: Sharp E.L. , Parsons S.A. , Jefferson B.
Published: May 2018

A number of water utilities have been experiencing operational difficulties during specific times of the year, associated with elevated levels of organics due to heavy rainfall or snow melt. Water samples were collected from Albert treatment works (Halifax, UK) and the natural organic matter (NOM) was characterised using XAD resin adsorption techniques. The addition of a cationic polyelectrolyte was employed to determine the charge density of the fractions. Results show that NOM fraction make-up changes throughout the year, with the fulvic acid fraction (FAF) showing the greatest increase during the autumn and winter period. The charge density of the FAF fraction also increases. The coagulation conditions for traditional coagulants, such as iron, are more affected by increased levels of organics than the novel coagulant also investigated, and the zeta potential range for optimum removal is narrower. Therefore, the conditions required for zero charge during coagulation varies with both raw water source and the coagulant type.
Enhanced biodegradability of UV and VUV pre-treated natural organic matter
Authors: Buchanan W. , Roddick F. , Porter N. , Drikas M.
Published: May 2018

A systematic investigation of the effectiveness of utilising UV (254 nm) or VUV (254 nm + 185 nm) photo-oxidation followed by biological treatment for the removal of natural organic matter (NOM) from a sample of drinking water was undertaken. The conditions of UV and VUV pre-treatment required to achieve maximum biological removal were determined. Positive correlations were observed between the production of smaller molecular weight molecules as shown by HPSEC and the decrease in dissolved organic carbon with increasing radiation dose. Similarly, the reduction of UV absorbance at 254 nm was found to correlate well with the observed increase in biodegradability of the UV-treated samples. UV pre-treatment resulted in the accumulation of biodegradable compounds from the breakdown of chromophoric material, although significant concentrations of refractory DOC remained even after the largest dose (140 J.cm−2). VUV pretreatment resulted in a rapid rate of mineralisation and fast formation of biodegradable compounds. VUV doses larger than 96 J.cm−2 were observed to reduce the apparent effectiveness of biological treatment. After the experimentally determined optimal VUV dose, approximately 80% of remaining DOC was biodegradable demonstrating that greater total DOC removal was achieved utilising VUV irradiation followed by biological treatment. The smaller doses of radiation required and greater bioavailability make VUV more effective than UV pre-treatment.
Micro-ground powdered activated carbon for effective removal of natural organic matter during water treatment
Authors: Matsui Y. , Murase R. , Sanogawa T. , Aoki N. , Mima S. , Inoue T. , Matsushita T.
Published: May 2018

For the purpose of enhancing the adsorption of natural organic matter (NOM) from water sources, commercially available powdered activated carbon (PAC) was further ground to produce PAC of micrometre-sized particles, and the effects of PAC size on adsorption of NOM were investigated. The micrometre-sized PAC (median particle diameter, 0.8 and 3.8 μm) removed NOM much better than did asreceived PAC (33 μm). Only one-tenth the dose of micrometre-sized PAC had the same effect as a full dose of the as-received PAC. The micro-grinding of PAC to micrometre sizes was effective at increasing its adsorption kinetics: adsorption of NOM to the micrometre-sized PAC reached 80% of equilibrium within only 1 min of contact time. The micro-grinding of PAC was also effective at increasing its adsorption capacity for NOM and polystyrene sulfonate-MW1800, but not for the small molecule phenol. This appeared to be due to an increase in mesopore surface area probably by fracture of ink-bottle pore structures during the micro-grinding. The micro-grinding enhanced the adsorption affinity of PAC for NOM that was strongly UV260-absorbent but not for NOM with low UV260 absorbance.
Natural organic matter – the relationship between character and treatability
Authors: Parsons Simon A. , Jefferson Bruce , Goslan Emma H. , Jarvis Peter R. , Fearing David A.
Published: May 2018

The characterisation and treatment of natural organic matter are becoming more important to the water utilities in the UK and around the world. This paper looks at the relationship between bulk and fractionated organic material and the performance of conventional water treatment processes.
Integrated operation of drinking water treatment plant at Amsterdam water supply
Authors: Bosklopper Th.G.J. , Rietveld L.C. , Babuska R. , Smaal B. , Timmer J.
Published: May 2018

Water treatment plants are in general robust and designs are based on the performance of individual processes with pre-set boundary conditions. It is assumed that an integral approach of the entire treatment plant can lead to more efficient operation. Taking into account the developments in sensoring, automation and computation, it is a challenge to improve quality and reliability of the treatment plants and to make maximal use of the installed infrastructure, postponing new investments.

At Amsterdam Water Supply (AWS), the first steps have been taken to come to an integral dynamic model of the total water treatment plant and the use of this model as an instrument for integral control. The parameters influencing the performance of the water treatment process will be incorporated in an overall model evaluating the goal factors quality (good, constant and reliable), quantity, costs, environmental impact (low residuals level), redundancy and flexibility. For several individual processes at AWS models have already been developed during the last few years, like models for the ozone process, biological activated carbon filtration and pellet softening. For the final calibration and validation pilot reactors are automated and on-line data are collected. Criteria for evaluation are developed to realise an optimal control of the individual processes in interaction with the goal factors of the total treatment process.
Improving automatic control of complex water systems, using AI techniques: design of an expert component for the alarms analysis
Authors: Gallone G. , Gueli R. , Patti A. , Tropea A.
Published: May 2018

The aim of this paper is to present an intelligent software tool, using Artificial Intelligence (AI) techniques, which allows the execution of an alarm analysis, during the remote sensing activity of complex plants. The AI component allows to identify all the primary faults of the system, discriminating them from the side effect alarms. In other words this tool shows which alarms are directly connected to primary faults and which alarms are consequential effects of the primary ones. The core of the software is an algorithm which uses a knowledge ontology and a set of alarm propagation rules, which are both based on a Multilevel Flow Modelling (MFM) paradigm. The algorithm has been tested implementing a rule based expert system (RBES) referred to an existing water plant. The main features of the water plant have been identified and all the main components and their possible alarm states have been analyzed to carry out the knowledge base.
Influence of algal organic matter on Escherichia coli behaviour
Authors: Bouteleux C. , Saby S. , Tozza D. , Cavard J. , Lahoussine V. , Mathieu L.
Published: May 2018

This study was undertaken after a report of drinking water industries which suggested the existence of a relation between algal proliferation (algal bloom) in resource water and coliform non-conformity in distribution networks. Our objective was thus to estimate if algal organic matter (AOM) could be used as a substrate by E. coli and explain its resuscitation in drinking water. For this purpose, E. coli was inoculated in sterile dechlorinated drinking water supplemented with organic matter of various origins in order to reach +0.2 (±0.1) mg BDOC L−1 (AOM, glucose or acetate). The results showed that the addition of AOM (naturally secreted by algae or released after a chlorine or ozone stress) in drinking water can represent a risk for water biological stability: indeed, AOM allowed either a higher cellular production, or a better maintenance of cultivability of E. coli than those observed in non-supplemented sterile drinking water, glucose or acetate solutions (in spite of equivalent additions of BDOC). Growth of E. coli was even up to 10 times higher in the presence of AOM coming from ozonated algae.
Reliability of valves and section isolation
Authors: Trietsch E.A. , Vreeburg J.H.G.
Published: May 2018

Section valves are essential for isolating incidents such as pipe bursts. In older networks where incidents occur most, valves have aged and their reliability has decreased. In addition, design rules or guidelines to locate valves in a network to ensure continuity of supply and to minimize effects on customers are generally lacking, as was concluded at an international workshop on valves in 2001.

Within the framework of the joint research programme of the Dutch water companies a methodology has been developed to translate the reliability of individual valves or clusters of valves into the reliability of supply for one or more sections in a network. The reliability of a section is characterised by performance indicators such as Customer Minutes Lost (CML): the average time in a year that a connection is without water due to an incident in the network. The methodology enables water companies to set priorities within their valve maintenance strategy, based on critical performance indicators, costs and maintenance frequency.

The methodology was translated into software and applied to a case study of the Dune Water Company of South Holland. The case study proved that the methodology and the software work well. Specific changes such as (re)location and enhancing the reliability of valves improve the performance and reliability of the network. As it is an emergency provision, investments can be done at ‘natural’ rehabilitation moments.
Analysis of system innovation in urban water infrastructure systems: an agent-based modelling approach
Authors: Kotz C. , Hiessl H.
Published: May 2018

The conventional urban water infrastructure concept, as it is implemented in industrialised countries as well as in urban areas in developing countries face increasing problems not only caused by investments required, but also by major problems with respect to retrofitting, upgrading and inflexibility with respect to future developments. Identifying alternative approaches to provide urban water services and finding ways to make a transition from the technological trajectory of the conventional urban water infrastructure system to more sustainable ones is of interest for both the developing and the developed countries. The paper describes essential aspects associated with innovation processes in urban water infrastructure systems and presents an agent-based model to simulate these innovation processes. Additionally, first simulation results are presented.
Rethinking urban water systems – revisiting concepts in urban wastewater collection and treatment to ensure infrastructure sustainability
Authors: Tjandraatmadja G. , Burn S. , McLaughlin M. , Biswas T.
Published: May 2018

Technology and economic development has led to the growth of megacities and urban centres with populations in the millions. Such population expansion and densification increases the strain on wastewater collection and treatment infrastructure, which has been largely based on an end-of-line centralised model. However, in megacities new challenges arise, because provision of suitable sanitation is expensive and it requires infrastructure expansion through construction of extensive sewer networks and larger capacity wastewater treatment plants, which consume more energy. Alternative disposal techniques for solid and liquid waste generated during the treatment process are required, because disposal solutions are decreasing as landfill costs rise and environmental standards are tightened, the latter reducing opportunities for land reuse. Additionally, mass wastewater discharge can have a detrimental impact on the ecology of water bodies and on the health of downstream populations, and requires suitable treatment before disposal. These challenges have the potential to offset the savings that the economies of scale offered by the traditional wastewater collection and treatment systems can impart. The need for affordable and effective wastewater systems in megacities requires the re-evaluation of traditional systems and the re-engineering of water and wastewater transport and resource concepts. Alternative concepts in wastewater collection and treatment, such as decentralised treatment, allied with innovative solutions using current and new technology could play a role in providing affordable and sustainable solutions to deal with the wastewater issue. This paper investigates the scope that integrated wastewater treatment and localised water reuse (in-line treatment, sewer mining), resource recovery (biogas, biosolids), operational changes (timed discharge of sewers, vacuum sewers) and biotreatment (e.g. vermiculture, faecal coliform removal) can play to guarantee the longevity of wastewater infrastructure in megacities. These alternatives offer increased treatment efficiency, recovery of value-added products, and reduce infrastructure cost, whilst maintaining health standards and reducing environmental discharge.
Can water institutions be cured? A water institutions health index
Authors: Dinar A. , Saleth R.M.
Published: May 2018

Once we agree that appropriate institutional arrangements play an important role in explaining the level of performance of the water sector across countries, we still face the overwhelming role of defining, measuring and comparing institutional performance. Unfortunately, water institutions in many countries are dated and weak. While the evaluation of water institutions is critical to identifying the gaps between needed and actual arrangements, and consequently deriving reform strategies, methodological issues and data problems present major challenges for such comparisons. This paper develops the Water Institution Health Index, based on a set of legal, policy, and organizational variables identified from an institutional decomposition approach. The index is constructed for 43 countries based on an international sample of 127 water experts; it evaluates and compares the relative health of water institutions and their components across these countries, and demonstrates the linkage and consistency of this index with other economic, social and governance indicators.
Estimation of willingness to pay for wastewater treatment
Authors: Genius M. , Manioudaki M. , Mokas E. , Pantagakis E. , Tampakakis D. , Tsagarakis K.P.
Published: May 2018

The aim of this study is to analyse residents' acceptability (willingness to use) of a wastewater treatment plant in their region and to evaluate citizens' Willingness to Pay (WTP) for the public provision of central wastewater treatment. We present a case study on rural and seaside tourist areas of the Municipalities of Lappaion, Georgioupolis and Krioneridas located in North-West Crete. For this purpose, a double bound dichotomous choice format contingent valuation study was conducted where members of 326 households were interviewed with face to face interviews. Mean WTP was found to be 44 € to be paid as an additional charge on the water bill, which is considerably higher than the estimated amount needed for the investment.
Drinking water policy in the frame of the Directive 2000/60/EC with emphasis on drinking water prices
Authors: Safarikas N. , Paranychianakis N.V. , Kotselidou O. , Angelakis A.N.
Published: May 2018

The Water Framework Directive (WFD) 2000/60/EC, which has been transposed into the national legislation with the Law 3199/2003 (MoEPPW, 2003), will cause substantial changes in the drinking water pricing policy and the domestic water authorities involved such as the Municipal Enterprises for Water Supply and Sewerage (DEYA). Up to date, drinking water pricing policy has been based only on the recovery of the economic cost and in some cases neither this. Therefore, domestic water is not priced taking into account its real cost. Based on data provided by 74 DEYA representing 2.10 million inh, the average water price is estimated to be 1.19 €/m3. Analysis of these data reveals a deviation of 41.67% from the real cost. The relation of consumers with the Enterprise, but also that of management and employees, should be a bidirectional relation, in order to be comprehensible by all. Thus, an agreement that will point out that the most excellent quality of water presupposes water policy which will consider sustainability and the current requirements of the Enterprise and of course the consumers should be established between them.
Source identification of groundwater pollution with the aid of multivariate statistical analysis
Authors: Wu T.N. , Huang Y.C. , Lee M.S. , Kao C.M.
Published: May 2018

With the aid of multivariate statistical analysis, this study attempted to predict possible underlying processes, attribute their influence, and isolate the distribution of sources that might threaten groundwater quality. Tainan County, Taiwan was employed as a case study, and 34 monitoring wells were sampled for routine lab analysis. Lab data of groundwater quality including pH, EC, hardness, chloride, sulfate, ammonia, nitrate, Fe, Mn, As, Zn, TOC and TDS were subjected to factor and cluster analysis. Principal component analysis (PCA) was utilized to reflect those chemical data with the greatest correlation, whereas cluster analysis (CA) was used to evaluate the similarities of water quality in groundwater samples. By utilizing PCA, the identified four major principal components (PCs) representing 78.8% of cumulative variance were able to interpret the most information contained in the data. PC 1 reflects the dominance of salinization, which was characterized by the elevated concentrations of EC, hardness, chloride and sulfate in groundwater. PC 2 with the positive loadings of TOC and pH but negative loading of nitrate is thought to be representative of organic pollution within the aquifer. PC 3 is regarded as mineralization factor on the basis of the loadings of manganese and zinc. PC 4 shows a strong monotonic relationship with ammonia concentration in the groundwater revealing the linkage with agricultural activity. CA results illustrated that coastal area was partially salinized as a result of seawater intrusion and part of salinization zone was also subjected to the impact of mineral dissolution.
A multiple objective mathematical model for daily coordinated multi-reservoir operation
Authors: Kim S.-K. , Lee Y. , Kim J. , Ko I.H.
Published: May 2018

In order to analyze and determine the daily release decisions of each dam in coordination with other dams in the basin for real-time operation, we developed a multiple objective mixed-integer goal programming (MOMIGP) model. We assumed that there are monthly target storages which have to be attained, and that the daily inflows for the next few days could be predicted in advance, while using the yearly averages thereafter. To account for the effect of daily river-routing, the lagged time water conveyance as a function of the volume of water released is incorporated into the model. With a multiple objective model, it is desirable to provide the DM (decision maker) with a wide range of choices of Pareto-optimal solutions. We suggest the use of the convex hull of individual maxima based interactive tchebycheff procedure (CBITP), in order to provide the DM with the most preferred daily release decisions in coordination with other dams in the basin.
Water Allocation by Weighting Factors Considering Multiple Criteria
Authors: Yi C.-S. , Choi S.-A. , Shim M.-P. , Kim H.-S. , Kim B.-S.
Published: May 2018

Typically, water has been allocated by some priority criteria like water rights in each country . However, water allocation by priority might have the problem in which the area of lowest priority can suffer from water shortage all the time. So, this study has tried to develop water allocation rules by weighting factor techniques. The weighting factors are estimated by sectoral and regional factors. The Analytic Hierarchy Process (AHP) is applied to estimate the sectoral factors and the regional factors can be divided by the regional-characteristic and regional-scale ends. The water allocation rules for the reservoir are developed by applying those weighting factors and the rules are applied to Andong dam reservoir which supplies the water to Busan-Si, Daegu-Si, and Goryeong-Gun, Korea in water deficit situation. As a result, all sectors and regions could share the burdens of water shortage by the water allocation using the relative weighting factors.
Results of the largest residential demand management program in Australia
Authors: Turner A. , White S. , Beatty K. , Gregory A.
Published: May 2018

This paper provides details and the results of an evaluation study carried out on the largest residential demand management program in Australia, the Sydney Water Corporation (SWC) ‘Every Drop Counts’ (EDC) residential retrofit program. The evaluation measured the water savings of program participants and compared them to a control group. Savings of 20.9 ± 2.5 kilolitres per household per annum (kL/hh/a) were found from statistical analysis of water meter readings of the sample of single residential households analysed. These individual savings effectively provide SWC with a potential total saving of 3,344 ± 400 megalitres per annum (ML/a) for the single residential houses retrofitted alone, i.e. 80% of the 200,000 households retrofitted to date. The evaluation identified that no ‘decay’ in average savings were found over the maximum four year period assessed. Other factors evaluated during the study included: analysis of individual water efficiency measures; comparison of savings with other evaluations; and savings related to occupancy ratio, geographical grouping, income category and defined socioeconomic categories.
Improving efficiency in water use and conservation in Spanish hotels
Authors: Cobacho R. , Arregui F. , Parra J.C. , Cabrera E.
Published: May 2018

Hotels are a fundamental component within the tourist Spanish sector, and their role in water management turns out even more relevant taking into account the fact that tourist areas, in which they are generally located, are water scarce. Trying to go further from the standard ratios and estimations to plan water conservation, this work intends to really measure and quantify water use in rooms. Only by doing this, can subsequent conservation actions, now able to be reliably specified for each specific use, achieve a real success.
Geographic Information System (GIS), leakage detection, mathematical modeling project for the validation of the investment planning at Valles del Tuy adduction water network (Venezuela)
Authors: Pérez J. , Roger A. , Noheda E. , Zoti P.
Published: May 2018

Valles del Tuy adduction network presented a great lack of knowledge concerning the system operational behavior. The discontinuity of water supply, water rationing by sector, nonexistence of operational control and changing regulation during the day by means of valves opening and closing made the system unpredictable. It was a real challenge to take into account all these factors and introduce them in a mathematical model. The result was a long-extended period model that was able to reproduce the system behavior with reliability in extended-period simulations. Based on it, a diagnosis of the critical points of the system was developed, that led to an improvement proposal. The proposals were focused on designing a controlled adduction system with the optimal operational behavior and without the necessity of making day-time changes for achieving a continuous and reliable water supply.
Ocean Dumping of Sludge vs. the Alternatives
Authors: Bogert I L , Sokol L J
Published: May 2018

Studies have been conducted in the East Coast Region of the United States challenging USEPA's determination that municipal sewage sludge dumpers fail to meet ocean dumping criteria.

Laboratory testing of liquid phase and bioassay and bioaccumulation of the Bergen County (New Jersey) Utilities Authority's digested sludge has been performed. The results indicated that the digested sludge falls within the required criteria and would not cause an adverse harmful effect on the marine environment. Inherent in the EPA's interpretation of the law is that other land-based alternatives to ocean dumping are not only feasible, but offer less relative environmental risks. The case against E PA's interpretation is increasingly apparent from studies indicating more severe risks from land-based alternatives.