bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic management of water distribution networks based on hydraulic performance analysis of the system
Authors: Massoud T. , Zia A.
Published: May 2018

In this paper the hydraulic performance of water distribution networks is evaluated by assessing the head values in demand points and velocities in pipes. To obtain the hydraulic parameters a head-driven simulation method is used. In this method, nodal outflows are not fixed and vary with nodal heads. Considering the possibility of a range of demand variations and mechanical and hydraulic failures in the system, nodal heads and pressure dependent outflows are obtained. Then, by using a mathematical function, the performance of the system is realistically evaluated. As expected, the level of service in the system is decreased when head and velocity values are out of the standard ranges. Also, the reliability of a water distribution network is calculated using the ratio of the pressure-dependent outflows to the demand values considering the probability of pipe failures. Comparing the level of service index and reliability applications on a test network, it can be concluded that the reliability method is not sensitive to high-pressure values in the system. However, in this situation the performance index shows a lower level of service in the network. This means that high reliability values guarantee a good connectivity and enough pressure to satisfy the required nodal outflows, although pressure values higher than the standard codes, which lead to more leaks and bursts, are not acceptable in water supply systems. Therefore, the existing definitions of reliability are not comprehensive enough to realistically evaluate performance of the system. Using the level of service index and the head-driven simulation method, the network performance under different normal and abnormal conditions can be appropriately evaluated for water companies.
Controlling water quality in intermittent supply systems
Authors: Coelho S.T. , James S. , Sunna N. , Abu Jaish A. , Chatila J.
Published: May 2018

In countries suffering from chronic water shortages, water distribution systems are often operated on an intermittent basis, leaving them unpressurised and allowing ingress of contaminated groundwater, particularly in areas lacking sewerage systems. The periods of stagnation can promote microbial regrowth, further compromising water quality. On the other hand, peaks in pressure and velocity in the pipe network lead to biofilm detachment events, thus releasing microbial cells that may escape the regular quality monitoring procedures and thus increase risk for the consumer. Finally, intermittent supply requires consumers to store water in household storage tanks, which often encourage bacterial regrowth. This paper reports on research undertaken in Jordan, Lebanon, Palestine, the UK and Portugal, which provided an improved understanding of the factors controlling bacterial concentrations in intermittent supplies, and presents an overview of the most important aspects of water quality control in intermittently operated networks.
Pressure management in Waitakere City, New Zealand - a case study
Authors: Pilipovic Z. , Taylor R.
Published: May 2018

In 1996, as part of Waitakere Council’s Water Cycle Strategy, a pressure standardisation programme to permanently lower the average supply pressure citywide was implemented with the aim of reducing water loss and water use. The experience gained during the 1994/95 Auckland water shortage had confirmed that there was considerable scope to reduce pressures in many areas.

Since 1996 water pressures have been reduced in over 60% of the reticulated area of the city, with the average pressure reduced from 710 kPa to 540 kPa. As a result of this programme water loss from the network has been reduced, there has been a reduction in the frequency of mains breaks and it is likely that the life of water pipeline assets has been extended. Furthermore both pressure and demand management initiatives have reduced per capita water use in the city by more than 10%.

A network computer model was used as a design tool to check the network under various pressure regimes and cost benefit analyses were carried out for various design scenarios. Fire sprinkler systems were checked as part of the design process. Minimum service standards were not reduced and in some cases pressures were actually increased. This paper covers the various aspects of the design, the implementation and the results of the pressure standardisation programme.
Shedding light on water quality: prospect for real-time control
Authors: Reynolds D.
Published: May 2018

Fluorescence spectroscopy has been used to measure gross water quality parameters and organic contaminants in a variety of water samples (surface, drinking and wastewater). Water samples exhibit characteristic fluorescence signatures and excitation and emission spectral data can be used to provide intensity data and “optical fluorescence fingerprints”. Sewage wastes exhibit broad band fluorescence centred at 350 nm and two relatively less intense bands at about 390 and 430 nm. Samples that have been treated in an aerobic digester show a substantial reduction in fluorescence around 350 nm. Normalised intensities in this region demonstrate good correlation with BOD, COD and TOC values (R2 values between 0.85 and 0.91). Drinking and surface waters also demonstrate unique fluorescence characteristics, which provide individual characteristic fingerprints. Results are presented that demonstrate the usefulness of fluorescence spectroscopy for the qualitative and quantitative detection of certain organic species present in different water types. Tryptophan is quantified in drinking and surface waters at levels around 8 × 10-9 mol l-1. Optical fluorescence fingerprints are unique for particular water types and are readily altered in the presence of organic contaminants including phenol and pyrene. The possibility of using fluorescence techniques for the continuous noninvasive monitoring of water quality is discussed.
An integrated approach to water distribution network monitoring and performance prediction using geographical information systems
Authors: Poulton M.
Published: May 2018

The deterioration of water distribution systems and the subsequent need for major rehabilitation has provided researchers with a challenge: to seek new techniques to facilitate decision-making and assist network planners. Consequently, a range of methods have been developed, concerning several key performance indicators. Those with the greatest potential tend to promote a pro-active approach to pipeline rehabilitation, by predicting future performance of individual or groups of pipes. Such an approach is essential if cost-effective solutions are to be found.

Prediction models are based on indicators that are perceived to be the most appropriate for measuring and comparing an aspect of performance. The level of “appropriateness” is influenced not only by the availability of data and the ease at which it can be recorded, but also its accuracy and unambiguity. Consequently, indicators such as burst rates are widely used to assess structural performance. Ideally though, a more direct measure of the condition of a pipe could be used, such as its remaining wall thickness. This has previously been largely disregarded, due to the lack of appropriate (non-destructive) measurement technology. However, technological advances are being made to enable the inline monitoring of pipes and determination of deficiencies (particularly corrosion pits in cast iron pipes).

This paper illustrates how online condition monitoring of distribution pipelines can be combined with existing prediction models, to facilitate the decision-making process. Integration is achieved through the use of a Geographical Information System (GIS), which greatly enhances representation of spatial and temporal information.
Determination of chlorine demand in water and wastewater chlorination by oxidation-reduction potential
Authors: Yu R.F. , Cheng W.P.
Published: May 2018

Chlorination is the most practical way for the destruction of pathogenic and other harmful organisms in water and wastewater treatment plants. However, highly erratic concentrations of ammonia is contained in most water and wastewater treatment plants, which will react to chlorine and seriously alter the required chlorine dosages in the control of chlorination. The conventional control of chlorine dosage is widely practical throughout the batch breakpoint chlorination test in the laboratory, which is not feasible for the requirement of real-time regulation of the chlorine demands. In this study, a simple automatic oxidation-reduction potential (ORP) titration system was developed for on-line determination of the chlorine demand. The experimental results showed that different decrease tendencies on ORP slope profiles were found to correlate to the ammonia concentrations in samples. In addition, the required chlorine demands were found to correlate to ammonia concentrations with a linear relationship. The ORP control strategy was, therefore, developed for on-line determination of the chlorine demands. Applying this ORP control strategy, the required chlorine demands were precisely predicted, and good disinfection efficiency was obtained in the wastewater chlorination experiments.
Profit and principles: finding a balance with the triple bottom line
Authors: Adam C.
Published: May 2018

Many Water Authorities throughout Australia have been through or are in the process of reforming their operations. For many, this means operating on a more commercial basis, with a progressively greater emphasis on the financial performance of their services. In many cases, these changes have led to a significant increase in the commercial performance of these businesses to the benefit of both the Water Authority and the broader community.

While recognizing commercial viability as a fundamental prerequisite for sustainable development, given the nature of the urban water industry and its central importance in maintaining living standards and addressing environmental issues, progressive managers are beginning to ask the question: “Is our commercial performance the single or even best measure of “success” in the management of our water services?”

Addressing this question is one of the issues at the forefront of development of the water industry. The search for a more sustainable management framework has led to the development and promotion of the Triple Bottom Line. However, is this new framework a useable tool or are the reports “greenwash, public relations ploys without substance”?

Cardno MBK’s experience in the development of a Triple Bottom Line Reporting format for one of Queenslands most progressive and environmentally responsible Councils provides an insight into the current state of development of the Triple Bottom Line and provides a contribution toward the development of a practical framework.
Cooperative facilitation and implementation of major trade-waste agreements
Authors: Earnshaw C. , Grigg A.
Published: May 2018

This paper provides a review of the trade waste agreement facilitation consultancy that Wagga Wagga City Council, Australia, has provided to major trade-waste sources since March 2000. The paper provides an insight into the role of a third-party facilitator in the establishment implementation, and conversion of an interim trade-waste agreement into a sustainable, term-based trade-waste agreement.
Water supply and sanitation planning model: a management tool for large Brazilian cities
Authors: Soares S.R.A. , Bernardes R.S.
Published: May 2018

The sanitary problems promoted by the rapid urbanization process in developing cities are usually resulted from the absence of planning, high population concentration and inadequate water and wastewater infrastructure for low income people. Because the provision and planning of water supply and is a complex task, a modeling approach was used to enhance the understanding of the process and the aspects involved. In the development of a model, not only the technical aspects were taken into account, but other aspects related to the provision of drinking water and the water resources protection were also analyzed, such as institutional, financial, socioeconomic, environmental and public health. In the modeling process two different methods of conceptualization were used to describe the urban water flow through the water and wastewater systems linked to various aspects related to their implementation in large developing cities. The urban water systems of five large metropolitan areas in Brazil were also evaluated for the complete model. It is expected that the modeling approach developed in this paper consists of a valuable methodology for water supply and sanitation planning in Brazilian cities, and other developing cities with the same characteristics. The suggested conceptual model could, at least, provide more than a starting point for a useful urban water management tool.
Nanofiltration membrane fouling by conventionally treated surface water
Authors: Liikanen R. , Kiuru H. , Tuhkanen T. , Nyström M.
Published: May 2018

Nanofiltration is a very effective technique for improving the removal of trace organics after a conventional chemical water treatment train. However, the fouling of the membranes decreases the applicability of the process, and thus, an understanding and control of membrane fouling are crucial for a more widespread use of nanofiltration in water treatment. The fouling of different nanofiltration membranes by pre-treated surface waters was investigated in a laboratory-scale filtration unit in this study. The results indicate that the traditional chemical treatment does not remove membrane foulants from the surface water. No correlation was found between the feed water constituents and nanofiltration performance, but most feed water components are expected to interact in membrane fouling. Actually, the performance of the nanofiltration process was more related to membrane than to feed water characteristics.
Fouling phenomena in a MBR: transmembrane pressure transients and the role of EPS (extracellular polymeric substances)
Authors: Cho B.D. , Fane A.G.
Published: May 2018

A membrane bioreactor (MBR), comprising an anaerobic reactor followed by crossflow MF, was operated at a fixed flux substantially lower than the nominal “critical flux” of the feed. A slow rise in transmembrane pressure (TMP) was observed which increased with imposed flux and organic loading to the bioreactor. After extended operation there was a sudden transition to a rapid TMP rise. This TMP profile was reproducible and depended on the imposed flux. The initial and gradual TMP rise is believed to be caused by the deposition of extracellular polymeric substances (EPS). The sudden rise in TMP is believed to be caused by local flux in regions of the membrane increasing (to maintain the fixed permeate flow) and exceeding the critical flux of the dominant foulant (biomass). Membrane autopsy revealed a significant and uneven distribution of fouling by EPS.
Modelling and simulation of filtration performance in membrane bioreactor systems for municipal wastewater treatment
Authors: Wintgens T. , Rosen J. , Melin T. , Brepols C. , Drensla K. , Engelhardt N.
Published: May 2018

The paper outlines a model of the filtration performance of submerged capillary microfiltration modules in membrane bioreactor applications for wastewater treatment. The model was implemented for process simulation and calibrated by using operating data of the full-scale municipal wastewater treatment plant Rödingen, Germany, operated by Erft River Association (Erftverband), which is equipped with activated sludge treatment and microfiltration units for biomass retention. Mathematically recordable foundations of filtration resistances, such as cake layer forming and fouling, are presented along with a mass transfer model, describing the concentration polarisation on the feed-side and its dependence on a multiphase flow regime. The model simulates the long-term decrease in permeability of the membranes and outlines the influence of main operating parameters on flux performance. After parameter fitting for one filtration unit, the permeability evolution for a second unit could be also calculated.
Tannery wastewater treatment: comparison between SBR and MSBR
Authors: Martinez J.M. , Goltara A. , Mendez R.
Published: May 2018

The beamhouse sections of tanneries produce around 45% of the total wastewater of factories. A beamhouse wastewater, collected after the oxidation of sulphide compounds and diluted to average COD and ammonium concentrations around 550 and 90 mg/L respectively, was treated separately in two reactors: a sequencing batch reactor (SBR) and a membrane sequencing batch reactor (MSBR). Both systems were operated for 150 days with similar conditions without sludge purge, operating at low feed to microorganisms (F/M) ratios and applying organic and ammonium loading rates up to 0.75 gCOD/L·d and 0.12 gNH4+/L·d respectively. The SBR achieved low ammonium and nitrogen removal rates and COD removal values close to 90%, which decreased dramatically during the last 30 days of operation. An important washout of microorganisms in the SBR was noticed due to the proliferation of filamentous bacteria. However, removal efficiencies close to 100% in ammonium and 90% in COD were achieved in the MSBR, and very stable operation was maintained.
Optimisation of water savings and membrane processes
Authors: Lipnizki J. , Casani S. , Jonsson G.
Published: May 2018

The Centre for Industrial Water Management is a co-operation between several technology service institutes, university institutes and water consuming companies in Denmark to promote concepts for cleaner production, water treatment and reduction of effluents in industrial production processes. This investigation focuses on two case studies from two of the industrial partners participating in this centre. The first case study is a texturiser of polyester yarn. Nanofiltration and reverse osmosis (RO) have been tested to clean the water streams from a dyeing bath and a reductive bath. It was shown that only the RO-process guaranteed a high rejection of salts under the process conditions. Furthermore, fouling could be analysed and reduced. The second case study is a manufacturer of functional proteins. An ultrafiltration system was used to concentrate the proteins from pig rind. It could be proved that the declining flux was caused by the adsorption of proteins on the membrane surface. To control fouling, a concept involving operation below the critical flux and a cleaning strategy is presented.
Description of different effects of in-line coagulation upon semi-dead-end ultrafiltration
Authors: Doyen W. , Vandaele R. , Molenberghs B. , Cromphout J. , Bielen P. , Baée B.
Published: May 2018

This paper describes the results of research focussed on the different effects of in-line coagulation (FeCl3), towards the operation of semi-dead-end UF for drinking water and process water production starting from surface water. In this research, firstly the effects of the use of FeCl3 on the formed cake were studied, by both direct and indirect measurements. Using the ESEM technique (environmental scanning electron microscopy), which enables one to make pictures of wet samples, we observed that cake thickness was much higher upon use of FeCl3 (20 instead of 2 μm). As a result, the cake porosity was calculated to be much higher with than without coagulant use (93% instead of 37%). From the stability (nonincreasing) of the starting transmembrane pressure (TMP) in the successive filtration cycles, upon semidead-end operation, it was concluded that cake layer was less prone to adhere to the membrane surface when using coagulant. This is even more emphasized once the dosing is stopped, as a consequence the TMP rises very steeply under difficult circumstances, such as; high flux rates, high water recovery rates, and the use of membranes made from polymers with high adsorption properties. Secondly, indirect effects of the use of coagulant on filtration behaviour were investigated. Thus, it was found that TMP increase in the filtration cycle was much lower, due to depth filtration in the formed high-volume cake, and TMP was much more stable over a long time. These observations were in good agreement with found higher cake porosity. Moreover, it was observed that due to the use of a coagulant, the influences of membrane polymer nature and membrane structure disappeared, cleaning action could be postponed and cleaning aggressiveness could be lowered. In addition, water recovery and flux rate could be increased, and influence of seasonal water quality variations could be better faced. Finally, it was found that the treatment of surface water with high DOC content (e.g. 10 mg DOC/l) was enabled.
Process combination of nanofiltration and adsorption: optimisation of an air and back flushing procedure
Authors: Meier J. , Neymann T. , Melin T.
Published: May 2018

A new process combination integrating adsorption on powdered adsorbent into a nanofiltration process is applied to landfill leachate treatment on a pilot scale. Lab scale experiments have shown that the permeate flux is significantly increased by the application of a flushing procedure combining permeate back flushing and feed and air cross flow flushing. In this paper an optimisation strategy for the flushing procedure is described and first experimental results are presented. These results indicate that the cross flow flushing velocity and the number of permeate side pressure pulses are the major factors of the flushing procedure.
Surface water clarification by ultrafiltration with an immersed membrane system: effect of coagulation/aeration on flux enhancement
Authors: Choksuchart P. , Héran M. , Grasmick A.
Published: May 2018

A new clarification system was developed to intensify a clarification step by ultrafiltration. Membrane modules equipped with capillary fibers were immersed in a reactor where a horizontal water circulation and a vertical air bubble circulation could assist in minimizing clogging inside the fiber network. Experiments were conducted with a clay particle suspension. Ferric chloride was added to induce coagulation of suspended particles. Results show that when filtering was operated under supracritical conditions clay deposit was observed on the membrane surface and a rapid increase in transmembrane pressure (TMP) value appeared. Air bubbling, and above all adding ferric chloride, allowed an actual enhancement of the filtering conditions. In optimal conditions, a very high concentrated suspension (5.0 g SS/L), filtering evolution was comparable to a clear water filtration until a 65 L/h/m2 permeate flux value (obtained under a 0.16 bar TMP), further a rapid fouling inside the fiber network appeared and obliged us to undertake specific membrane cleaning. The chosen membrane cleaning procedure showed that the particle deposit was the main fouling cause when filtering above the critical conditions.
Decentralized wastewater management: challenges and opportunities for the twenty-first century
Authors: Tchobanoglous G. , Ruppe L. , Leverenz H. , Darby J.
Published: May 2018

Decentralized wastewater management (DWM) may be defined as the collection, treatment, and reuse of wastewater from individual homes, clusters of homes, subdivisions, and isolated commercial facilities at or near the point of waste generation. In some areas, the liquid portion could be transported to a central point for further treatment and reuse. At the time of writing (2002), more than sixty million people in the United States live in homes where individual decentralized systems are used for wastewater management. Further, the U.S. EPA now estimates that about 40 percent of the new homes being built are served with onsite systems. In the early 1970s, with the passage of the Clean Water Act, it was often stated that it was only a matter of time before sewerage facilities would be available to almost all residents of the continental United States. Now, more than 25 years later, it is recognized that complete sewerage of the entire U.S. may never be possible, due to both geographic and economic constraints. Because complete sewerage is unlikely in the foreseeable future, it is clear that DWM systems are needed for the protection of public health and the environment and for the development of long-term strategies for the management of our water resources. The challenges and opportunities for DWM systems in the twenty-first century are discussed in this paper.
Performance of a pilot scale membrane bioreactor coupled with SBR (SM-SBR) - experiences in seasonal temperature changes
Authors: Shin H. , Kang S. , Lee C. , Lim J.
Published: May 2018

The submerged membrane bioreactor is one of the recent technologies for domestic wastewater treatment. In this study, the performance of the pilot-scale submerged membrane bioreactor coupled with sequencing batch reactor (SM-SBR) was investigated. The reactor was operated in sequencing batch modes with a 3-hour cycles consisting of anoxic and aerobic conditions to treat organics, nitrogen and phosphorus. Despite large fluctuations in influent conditions, COD removal was found to be higher than 95%. Sufficient nitrification was obtained within a few weeks after start-up and during the stable period. Moreover, complete nitrification occurred despite of short aeration time. Total nitrogen (TN) removal efficiency was up to 85%. The insufficient organic loading caused by the membrane fouling led to the increase of HRT, leading to endogenous respiration and/or deactivation of nitrifying microorganisms. DGGE patterns confirmed the shift in microbial community structure. The ammonia-oxidizers (i.e. Nitrospira) became dominant in the mixed liquor during long-term operations. Nitrification and denitrification processes were greatly affected by the temperature, while organic removal and phosphorus removal efficiencies were relatively stable below 15°C.
Exploratory study on reusing water treatment works sludge to enhance primary sewage treatment
Authors: Guan X.-H. , Shang C. , Yu S.-M. , Chen G.-H.
Published: May 2018

This paper focused on an exploratory study on reusing waste sludge of a local water treatment works (referred to as “alum sludge”) to enhance the removal of both SS (suspended solids) and COD (chemical oxygen demand) from sewage. Laboratory jar tests were conducted using the raw sewage and the alum sludge taken from a local sewage treatment works with variations in sludge dosages, aging times and pH conditions. It has been found that adding alum sludge at dosage around 20 mg/l as Al to the sewage can increase the SS removal by more than 20% and the COD removal by at least 15%, compared with the control tests without alum sludge addition. The pH of sewage, adjusted from 5 to 9, had little impact on the SS and COD removal induced by the alum sludge. However, the alum sludge aging time substantially affected the SS and COD removal. Experiment results suggested that sweep flocculation and physical adsorption play the key roles in enhancing both SS and COD removal from the raw sewage.
Role of variability in design, implementation, and interpretation of microbial inactivation studies
Authors: Rosen J.S. , Najm I. , Sobrinho J. , Via S.
Published: May 2018

In developing a Ct (concentration × time) table for the inactivation of Cryptosporidium with ozone it has been necessary to incorporate an uncertainty factor that can be applied to calculated Ct values to take account of the significant variability in inactivation results. This paper presents an approach for partitioning the overall variability into two types. That due to analytical and experimental error is shown to clearly outweigh that due to differences in water matrices and oocyst resistance to disinfectant. The results support the use of confidence intervals calculated about the mean inactivation coefficients calculated with existing data, leading to the operation of ozonation with sufficient safety factors to protect public health.
Using DNA microarrays to detect multiple pathogen threats in water
Authors: Straub T.M. , Quinonez-Diaz M.D. , Valdez C.O. , Call D.R. , Chandler D.P.
Published: May 2018

We present four studies that illustrate the use of DNA microarrays for the detection and subsequent genotyping of waterborne pathogens. A genotyping array targeting four virulence factor genes in enterohemorrhagic Escherichia coli (EHEC) was tested. The arrays were clearly able to differentiate between E. coli O157:H7 genotypes and E. coli O91:H2. Non-pathogenic E. coli and non-target organisms were not detected on this array. In the second study, an hsp70 gene single nucleotide polymorphism (SNP) array for specific Cryptosporidium parvum detection was constructed to differentiate between principle genotypes. SNPs, and hence differences between genotypes, were easily detected on this type of array. In the third study an array for Helicobacter pylori was tested for simultaneous SNP discrimination and presence or absence of virulence factor genes. Results from this study showed that both SNP discrimination for some conserved genes, and the presence or absence of virulence factor genes was possible. In the fourth study, multiplexing was achieved by direct hybridization and detection of mRNA to the array. For highly expressed genes, visible signal was detected at 312.5 ng of total RNA, indicating that these new methods may have sufficient environmental sensitivity without the need to perform PCR.
Risk assessment of Legionella and enteric pathogens in sewage treatment works
Authors: Medema G. , Wullings B. , Roeleveld P. , van der Kooij D.
Published: May 2018

Exposure of sewage treatment workers to Legionella pneumophila and enteric pathogens through aerosols at different sewage treatment installations was quantified. The presence of Legionella sp. and L. pneumophila in water and air samples at different sewage installations was determined by cultivation, Direct Fluorescence Assay and PCR. Simultaneously, coliforms, F-RNA phages and spores of sulphite reducing clostridia (SSRC) were enumerated in water and air. For enteric pathogens, the aerosolisation efficiency of coliforms, F-RNA phages and SSRC were combined with published data on the concentration of Campylobacter, enteroviruses and Cryptosporidium parvum, respectively, in wastewater to calculate the concentration of these pathogens in the air. The frequency and duration of the presence of sewage workers at or in the different installations was determined by a questionnaire. The concentration of micro-organisms in the air and the data on the presence of workers at these locations were combined into an estimate of the exposure to Legionella and the enteric pathogens. Legionella was detected in all wastewater samples (n=7) with PCR, in concentrations of approximately 105 per ml, but not with the culture method (<20–<200 /ml). Legionella spp. and L. pneumophila were detected in air samples of 10 m3 with PCR at 3 of the 5 sewage treatment plants tested. Samples of air above trickling filters (2/2), aeration tanks (2/2), the screen (1/1) and the belt press (1/1) were positive for Legionella. The concentration ranged from 0.56–56 per m3 of air with PCR, but again no Legionella were detected in any of the air samples with the culture method. The Legionella-concentration (determined by PCR) in the air were low compared to published data on Legionella concentrations in the air at outbreak sites (determined by culture). Hence, the risk of legionellosis to sewage workers was considered low. The calculated concentrations in air ranged from very low (<0.001/m3 up to 0.3–17/m3 at sites with high aerosolisation). During cleaning activities, the concentrations rose up to 100/m3. These concentrations were translated into the probability of infection using published dose-response models. The annual probability of infection for sewage workers was high (worker with average exposure 19%, high exposure worker (95-percentile) 100%). Therefore, measures to reduce aerosol formation or exposure to aerosols (both technical and protective) should be considered. Reduction of exposure to aerosols will not only reduce the risk due to enteric pathogens, but also to endotoxins, Legionella and other pathogens.
Washroom behaviour and users' perceptions of “novel” water-efficient appliances
Authors: Hills S. , Birks R.
Published: May 2018

A variety of washroom appliances are available which claim to be water efficient. However there are a number of “human” factors, which may adversely affect the water savings actually achieved when the appliances are installed. These were investigated as part of Thames Water's “Watercycle” project at the Millennium Dome, where a range of water efficient devices, such as infra-red controlled taps, waterless urinals and dual-flush toilets, were installed in the washrooms and compared to standard appliances. As well as monitoring actual metered water usage, to help understand how users interacted with the range of appliances, the work also involved a survey conducted by interview and an observational study of water using behaviour in the washrooms. The results highlighted significant differences between males and females, for example females were more likely to wash their hands following toilet use. With respect to “novel” dual flush toilets and waterless urinals, both fairly unusual in the UK, they were well received by users. In contrast, the infra-red controlled taps were found difficult to use and least likely to be accepted for use in the home. Relevant signage and labelling was found to have a positive effect on conservation and user opinions.
Communicating water conservation: how can the public be engaged?
Authors: Howarth D. , Butler S.
Published: May 2018

In 2001 the Environment Agency and Thames Water completed a collaborative research project “The Effectiveness of Marketing Campaigns in Achieving Water Efficiency Savings”. The project attempted to assess the effectiveness of a water efficiency campaign in a residential area of 8000 properties. The results showed that the campaign had no significant effect on water demand both at the individual property level and the total flow into the area. Responses to direct questions about the campaign indicated that at most 5% had noticed it despite the fact that 25% claimed to read the local newspaper and listen to the local radio station used for the campaign, and the fact that a leaflet was sent to all households. The market research provided some clues as to why the customer response to this campaign was so disappointing, principally because the public regard water as low priority compared to other environmental issues. Other research is reviewed that provide additional reasons for the unwillingness of the public to engage on this issue. This paper reviews “success stories” from Phoenix, Arizona and Singapore and identifies the main learning points from these programs. Article 14 of the Water Framework Directive calls for active involvement in water policy. An assessment is made of what this might mean for public participation in water conservation programs.
Optimal planning model for rehabilitation of water networks
Authors: Kim J.-H. , Baek C.-W. , Jo D.-J. , Kim E.-S. , Park M.-J.
Published: May 2018

An optimal planning model for rehabilitation of water networks is presented. Capital costs (replacement, rehabilitation and repairing costs), benefits (by the reduction of pumping cost and leakage cost), and hydraulic reliability are used for making an optimal decision for the rehabilitation plan of a water pipe network. KYPIPE is used for checking the hydraulic reliability. A multi-objective optimization model is successfully developed in this study. And the task is tackled using a new meta-heuristic algorithm, Harmony Search, for solving a large optimization problem to which conventional optimization techniques are poorly suited. Five different models with different objective functions are developed and tested according to various conditions considered in this study. These models provide more options for the rehabilitation of pipe network systems compared to previously suggested models in the literature.
Size exclusion chromatography (SEC) with multiple detectors: a powerful tool in treatment process selection and performance monitoring
Authors: Amy G. , Her N.
Published: May 2018

The traditional application of size exclusion chromatography (SEC) with single wavelength UV detection (at 254 nm) for molecular weight (size) estimation can be expanded to include multiple detectors that provide insight into the size, structure, and functionality of natural organic matter (NOM). Other detectors include, foremost, on-line dissolved organic carbon (DOC) as well as fluorescence and variable wavelength UV. SEC coupled with this range of detectors elucidates unique signatures for different types and sources of NOM including allochthonous versus autochthonous (i.e., algal organic matter (AOM)) versus wastewater effluent (i.e., effluent organic matter (EfOM)). Also revealed by SEC are preferential NOM removals and/or transformations by various water and wastewater treatment processes as well as identification of problematical NOM components (e.g., membrane foulants).
The efficiency of the ILUV oxidation method for organic nitrogen analysis
Authors: Smith Baxley J. , Hepplewhite C. , Karanfil T.
Published: May 2018

A new approach to measure dissolved organic nitrogen in fresh waters was developed as an alternative to more expensive techniques, such as traditional UV oxidation and high temperature oxidation and to more labor-intensive techniques that produce hazardous by-products, such as persulfate oxidation. The new approach, called the individual lamp UV (ILUV) method, was applied to model compounds and humic substances. For the selected model compounds, ethylenediaminetetraacetic acid, glycine and urea, the ILUV oxidation method resulted in 93% to 114% recoveries. In the case of humic substances, the recoveries ranged from 100% to 126%. It was found that the ILUV method is a simple, cheap and promising method for determination of DON in natural waters.
Influence of UV irradiation and UV/hydrogen peroxide oxidation process on natural organic matter fluorescence characteristics
Authors: Hofbauer D.E.W. , Andrews S.A.
Published: May 2018

Natural organic matter is ubiquitous in aquatic systems, and has long been associated with disinfection by-product (DBP) formation during chlorination in water treatment plants and distribution systems. In this study modelled water was irradiated with either ultraviolet (UV) lamps or with UV combined with the addition of hydrogen peroxide (H2O2). The changes in the fluorescence intensity between the pretreated and post-treated samples were measured to determine the changes in the molecular size distribution of this reactive fraction of NOM. It was determined that the UV/H2O2 process reduces the concentration of these potential DBP precursors more effectively than UV irradiation alone.
Characterising natural organic matter flocs
Authors: Jarvis P. , Jefferson B. , Parsons S.A.
Published: May 2018

Using a dynamic optical technique and settling column apparatus, natural organic matter floc structural characteristics were monitored and evaluated over a one year period to monitor the seasonal variation in floc structure at optimum coagulation dose and pH. The results show that flocs changed seasonally with different growth rates, size, response to shear and settling rate. Autumn and summer flocs were shown to be larger and less resistant to floc breakage when compared to the other seasons, suggesting reduced floc strength. Floc strength was observed to increase with smaller median floc size. The results of the settling tests indicated that the autumnal flocs were of a more open structure which helped to explain why they settled faster. In summary, the autumnal flocs had significantly different floc characteristics although it was difficult to relate the floc structure with the incoming water characteristics.
Advanced oxidation processes: flowsheet options for bulk natural organic matter removal
Authors: Murray C.A. , Parsons S.A.
Published: May 2018

Advanced oxidation processes have been reported to have the potential to remove natural organic matter from source waters. Of these Fenton's reagent, photo-Fenton's reagent and titanium dioxide photocatalysis are the three most promising processes. Compared to conventional coagulation/flocculation processes they have higher removal efficiencies in terms of both dissolved organic carbon and UV254 absorbance. Under optimum reaction conditions all three remove over 80% dissolved organic carbon and 0% UV254 absorbance. In addition the enhanced removal of natural organic matter leads to a corresponding reduction in the formation of disinfection by-products following chlorination of the treated water. Advanced oxidation processes give enhanced removal of organic species ranging from low to high molecular weight while coagulation/flocculation is inefficient at removing low molecular weight species. One additional benefit is all three processes produce less residuals compared to conventional coagulation, which is advantageous as the disposal of such residuals normally contributes a large proportion of the costs at water treatment works.
NOM control options: the next generation
Authors: Fearing D.A. , Banks J. , Wilson D. , Hillis P.H. , Campbell A.T. , Parsons S.A.
Published: May 2018

Seasonal periods of high rainfall have been shown to cause elevated natural organic matter (NOM) loadings at treatment works. These high levels lead to difficulties in removing sufficient NOM to meet trihalomethane (THM) standards, and hence better alternative treatments are required. Here three options for the removal of NOM either by optimising current coagulation and pre- or post-coagulation have been studied. NOM can be isolated into fractions distinguished by their hydrophobic and hydrophilic characteristics. Previous studies have shown that certain fractions are more recalcitrant to treatment during the times of high loadings. By optimising coagulation for these fractions a staged coagulation is proposed, the results of which found that although no significant dissolved organic carbon (DOC) or UV absorbance at 254 nm (UV254) was observed filter run times were significantly increased. Secondly a novel magnetic ion exchange process (MIEX®) developed specifically for the removal of NOM was trialled and the results of a combination of ferric coagulation and MIEX® showed that although the final DOC of the water was not significantly reduced the THM formation potential (THMFP) was reduced by more than 50% for the lower molecular weight (MW) compounds that are known to be untreated by conventional coagulation. Finally the addition of a range of adsorbents including carbons, hydroxides and clays to both the raw water and the isolated low MW fraction showed that an increase in DOC and UV254 removal was achievable. The findings of the three trials showed that at the difficult to treat times of the year, optimised removal for the low MW fractions could prove to be vital if legislation is changed.
NOM removal from different raw waters by membrane filtration
Authors: Frimmel F.H. , Saravia F. , Gorenflo A.
Published: May 2018

In this study natural organic matter (NOM) removal by ultra- and nanofiltration from four different raw waters was investigated. The experiments were carried out with a flat channel cross flow unit and with a pilot unit equipped with two parallel spiral wound modules. NOM rejection was characterized using 13CMAS-NMR spectroscopy, scanning electron microscopy (SEM) and size exclusion chromatography with online DOC detection (LC-OCD). Additionally measurements, such as DOC, UVA (254nm and 436nm), AOX- and THM-precursors, ion concentration, turbidity, etc. were made on raw waters, permeates and concentrates. The results indicate that NOM removal by nanofiltration for all water sources is almost complete (>90%), while NOM removal by ultrafiltration depends on raw water chemistry, especially ionic strength. Solid state 13C-NMR spectra of freeze-dried NOM deposits on membrane surfaces suggest the presence of structural polysaccharides (such as chitin and cellulose). SEM images confirm the NMR-results: after filtration, inorganic deposits and algae like structures were found on membrane surfaces.
Removal of microcystin-LR from drinking water with TiO2-coated activated carbon
Authors: Kim S.-C. , Lee D.-K.
Published: May 2018

TiO2-coated granular activated carbon was employed for the removal of toxic microcystin-LR from water. High surface area of the activated carbon provided sites for the adsorption of microcystin-LR, and the adsorbed microcystin-LR migrated continuously onto the surface of TiO2 particles which located mainly at the exterior surface in the vicinity of the entrances of the macropores of the activated carbon. The migrated microcystin-LR was finally degraded into nontoxic products and CO2 very quickly. These combined roles of the activated carbon and TiO2 showed a synergistic effect on the efficient degradation of toxic microcystin-LR. A continuous flow fluidized bed reactor with the TiO2-coated activated carbon could successfully be employed for the efficient photocatalytic of microcystin-LR.
Organic THMs precursors removal from surface water with low TOC and high alkalinity by enhanced coagulation
Authors: Rizzo L. , Belgiorno V. , Meriç S.
Published: May 2018

NOM removal from surface waters is needed because of potentially carcinogen compound (trihalomethane, THM) formation due to reaction between NOM and free residual chlorine used for disinfection. The stringent limits for THMs (e.g., 30 μg/l in Italy) force conventional drinking water treatment plants to increase TOC removal efficiency by enhanced coagulation. This study was performed on 17 samples taken from a surface water resource with low TOC content (<3 mg/l) and high alkalinity (190 mg as CaCO3/l) to remove TOC and other parameters (DOC, UV254, SUVA, turbidity), typically used to characterize NOM content. Four different coagulants (Al2(SO4)3·18H2O, FeCl3·6H2O, FeSO4·7H2O and PACl) were used in jar test without adding polymer as flocculant. There was no correlation between DOC and SUVA in raw and treated water. TOC removal efficiencies (15–30%) required by the USEPA D/DBPs rule were obtained using 30–50 mg/l alum, 30–50 mg/l of FeCl3, and less than 20 mg/l of PACl (as Al2O3, 10%). The use of PACl is suggested for both lesser TTHMFP and residual Al levels (<100 μg/l) occurrences without any pH adjustment.
Removal of humic substances by chitosan
Authors: Vogelsang C. , Andersen D.O. , Hey A. , Håkonsen T. , Jantsch T.G. , Müller E.D. , Pedersen M.A. , Vårum K.M.
Published: May 2018

Results from laboratory tests, conducted to study different aspects regarding the removal of humic substances by the environmentally friendly cationic biopolymer chitosan, are presented. Chitosan was shown to be an efficient remover of the high molecular weight humic substances, significantly reducing the colour and UV absorbance in typical humus-rich Norwegian surface waters with low particle content. By adding small amounts of Fe3+ together with a reduced dose of chitosan, it was possible to significantly improve the removal of the medium molecular weight humic substances. The highest charged (low Fa) chitosans were the most efficient coagulants, indicating that charge neutralisation was the triggering mechanism for the coagulation. Surface charge measurements of coagulated raw water gave strong indications in the same direction. However, net positive surface potentials of flocs after neutralisation indicated that excess chitosan participated in the build-up of flocs, suggesting that bridging or electrostatic patch flocculation could be important mechanisms during flocculation. However, the molecular weight of chitosan had no significant influence on the maximum removal of the humic substances.