bluuebunny/crossref_metadata_2025 huggingface dataset:
Drinking water in Michigan: source, quality, and contaminants
Authors: Nathan Vincent R.
Published: May 2018

The Michigan Safe Drinking Water Act (Act 399) was enacted in 1976 and enables the Michigan Department of Environmental Quality (DEQ) to maintain the state's authority over drinking water in the state. The DEQ also contracts with local health departments to maintain non-community programs in each county. Private water wells throughout the state are clearly the most troublesome for users and regulators. An abundant array of contaminants (e.g., pesticides, metals, etc.) may impact wells without the user's knowledge. Most private wells are only inspected when they are installed and have no further regulatory requirements. With regards to contaminants in public systems, lead is problematic. Irregardless of the source or treatment, the piping infrastructure leading to and inside the home can be a source affecting the quality. Thus, the problem of lead in drinking water can be from the service lines, the pipes inside the home, the solder connecting the pipes, or in some case the treatment chemicals used for disinfection.
Municipal water pricing and tariff design: a reform agenda for South Asia
Authors: Whittington D.
Published: May 2018

The water tariffs currently in use in most cities in South Asia are not accomplishing their principal objectives. They are not generating sufficient revenues to ensure that utilities can recover their financial costs. They are not sending the correct economic signals to households, i.e., that water is scarce and must be treated as a valuable commodity. They are not helping the majority of the poor households, many of whom are not connected to the piped distribution system. This paper describes the major elements of a package of pricing and tariff reforms that are needed in the municipal water supply sector in many South Asian cities. The recommended set of reforms has three distinct parts: (1) expanding the customer base and making sure connections are metered so that pricing policies can be implemented; (2) changing the way water bills are calculated for households, and for industrial and commercial customers; and (3) putting in place the policies to protect poor households during the reform process. The following pro-poor policies are recommended: (1) ensuring that poor households (and others) can have a private water connection when they want it; (2) subsidizing upfront connection costs, not volumetric water use; (3) providing public taps as a water source of last resort for the very poor; (4) legalizing water vending and selling by neighbors; and (5) not giving private operators exclusive rights to provide water within a service area.
Making regulatory mechanisms work: lessons from cases of Private Sector Participation
Authors: Frade T. , Sohail M.
Published: May 2018

This paper is about the regulation of private sector participation (PSP) in public water utilities. Using case studies from Argentina, Chile and the United Kingdom, it identifies and discusses the regulatory mechanisms that have been introduced and the issues surrounding information access, price and service quality regulation. The paper also analyzes what measures have been implemented in these three cases in order to achieve regulatory accountability, independence and an adequate level of financial and human resources.

The method adopted was case survey including the analysis of official regulatory documents and other relevant material and validation by an expert panel. It investigates the conditions that are necessary for regulatory mechanisms to be implemented and operated effectively in each context, and draws out some general conclusions for areas of improvement.
Policy and law for addressing poverty, race and gender in the water sector: the case of South Africa
Authors: Schreiner Barbara , van Koppen Barbara
Published: May 2018

The aims of the new water policies and laws of post-apartheid South Africa are to contribute to the eradication of the country's widespread poverty and to redress historical race and gender discrimination with regard to water. After placing these policy and legal changes in a historical context, the paper discusses their operationalization and impact during the first years of implementation. Three key aspects are highlighted. The first aspect concerns internal changes within the implementing government department, the Department of Water Affairs and Forestry (DWAF). The second aspect regards water services and sanitation directly targeted at poor women and men. Lastly, the paper discusses the emerging equity issues in public participation processes, as an illustration of the new approach to integrated water resources management.
Challenges to community participation in watershed management: an analysis of fish farming activities at Saguling Reservoir, West Java - Indonesia
Authors: Gunawan Budhi , Takeuchi Kazuhiko , Abdoellah Oekan S.
Published: May 2018

Community participation is a precondition of integrated watershed management. However, during the implementation phases, some people may not participate in or share the benefits of watershed management. There are several reasons for this and the following paper seeks to show the response by fish farmers from Saguling Reservoir, West Java, Indonesia, to environmental problems and the concept of integrated watershed management. The study indicates that while farmers have a moderate understanding of interrelated environmental problems, there is little willingness to share the benefits of investment in watershed management. Nevertheless participation in solving local environmental problems can be developed and incorporated in watershed management plans.
Utility-small water enterprise partnerships: serving informal urban settlements in Africa
Authors: Njiru Cyrus
Published: May 2018

Sustainable development cannot be realised when a large proportion of people do not have access to improved water services. Indeed, despite concerted international effort and publicity made in the last two decades to increase coverage of improved water and sanitation services, the number of people without improved water and sanitation services continues to increase. Water utilities are not serving a large proportion of the urban population and small water enterprises (SWEs) have moved to fill the gap. This paper looks at the growing urban water problem and outlines the role played by SWEs in providing water services to those un-served or under-served by water utilities. Typical constraints faced by SWEs are outlined and the rationale for developing utility–SWE partnerships for the benefit of water consumers (customers) is provided. Potential opportunities for developing utility-SWE partnerships are discussed. The paper argues that utility-SWE partnerships can enable SWEs to provide affordable good quality water services to customers, while providing benefit to the utility and thus also assisting the utility to meet its mandate. The paper proposes win–win utility-SWEs partnerships aimed at achieving the objectives of utilities and SWEs while improving water services to customers in informal urban settlements of developing countries, with a focus on sub-Saharan Africa.
Sustainable community water: managing supply systems in the mid-hills of Nepal
Authors: Bhandari B.S. , Grant M. , Pokharel D.
Published: May 2018

This study examines the sustainability of rural drinking water supply (DWS) projects installed by non government organizations (NGOs), international non government organizations (INGOs) and government organizations (GOs) in two districts in the mid-hill region of Nepal. Comparative analyses of different systems installed by NGOs, INGOs and GOs, which portray the work and improvements needed for sustainability, are determined. This study shows that INGO installed projects are moving forward to sustainability in terms of performance compared to NGOs and GOs. One of the prime reasons of failure to maintain sustainability is poor involvement of women from the projects' early stages. A systematic random household survey was conducted of selected projects in the study area and this showed that most of the rural DWS projects need to improve management practices and gender equality during planning as well as operation and maintenance phases. Rural people are satisfied with DWS project water availability in their communities. Results indicate that water accessibility fails to have significant impacts on rural livelihood especially for the rural poor.
Enhancing community welfare through improved water quality: a case for applying staggered pollution charges in the river Musi sub-basin of Andhra Pradesh, India
Authors: Chatterjee Tishya
Published: May 2018

In conditions of severe water-pollution and dormant community acceptance of accumulating environmental damage, the regulator's role goes beyond pollution prevention and more towards remediation and solutions based on the community's long-term expectations of economic benefits from clean water. This paper suggests a method to enable these benefits to become perceptible progressively, through participatory clean-up operations, supported by staggered pollution charges. It analyses the relevant literature on pollution prevention and applies a cost-based “willingness to pay” model, using primary basin-level data of total marginal costs. It develops a replicable demand-side approach imposing charge-standard targets over time in urban-industrial basins of developing countries.
Irrigators and the new policy paradigm – An Australian case study
Authors: Bjornlund Henning
Published: May 2018

The new water policy paradigm has been vigorously implemented and pursued in Australia since the early 1990s. This paper analyses how elements of this new paradigm have been adopted and perceived by irrigators within two different states of the Murray-Darling Basin in south eastern Australia and how these policies have had an impact on the lives and aspirations of farming families. The analyses are based on 700 telephone interviews with irrigators who have bought and sold water on the markets for temporary or permanent water as well as irrigators who have never traded. The analyses suggest that the impact and perception of the new policy instruments are not primarily delineated between buyers and sellers in the water market as could have been expected, but by the irrigators' position in the adjustment process, which determines how the irrigators are active in the water market.
Overcoming third party effects from water trading in the Murray–Darling Basin
Authors: Etchells Teri , Malano Hector M. , McMahon Thomas A.
Published: May 2018

Water markets have great potential to increase the efficiency of water use. However, the very process of transferring a water entitlement can result in third party effects. Specifically, there are three types of impact that can affect the entitlements of third party irrigators: volumetric reliability, delivery reliability and water quality effects. In each case, policy makers must decide whether they will try to prevent the impacts and whether they will force traders to internalise third party effects. Potential strategies range from non-interventionist options, such as restricting trade, to market interventions, such as exchange rates, which adjust traded entitlements to account for volumetric externalities.
Small dams safety issues – engineering/policy models and community responses from Australia
Authors: Pisaniello John D. , Zhifang Wu , McKay Jennifer M.
Published: May 2018

Dam safety is a serious issue worldwide. However, in many countries, for example, China and Australia, although much attention is being devoted to the medium to large-scale dams, little or no attention is being paid to the serious potential problems associated with smaller dams, particularly the potential “cumulative domino effect” failure risk to the larger public dams. Farmers in Australia have often overlooked the common law obligation to review/design dams in line with current standards because of high engineering consulting costs. This leaves them vulnerable to litigation if their dam fails and the downstream community is susceptible to unacceptable risk levels. To overcome this problem, an innovative Australian-developed cost-effective spillway design/review procedure has been developed to minimise cost burdens to dam owners and encourage better dam safety management. A recent survey undertaken in the Australian “policy model” State of Victoria to test community attitudes to the procedure and implemented dam safety and water allocation policy is also reported here. This survey clearly demonstrates that farmers require more than awareness and encouragement in order to ensure that they look after their dams properly.
Options for the future: balancing urban water supply and demand in Beijing
Authors: Wang Can , Whitehead Camilla Dunham , Chen Jining , Liu Xiaomin , Chu Junying
Published: May 2018

Beijing is facing the considerable challenge of water shortage, as it is just able to meet current water demand in a year with average precipitation and a shortfall between water supply and demand is estimated to be around 1.8 billion[109] cubic meters (BCM) by 2010. Aiming to find the solution to such a severe challenge, this paper investigates Beijing's current and future water resources availability and water-use configurations, as well as past and current effort on both areas of water supply and demand. The analysis shows a continuously growing demand for water and an aggravating deficit of traditionally available water resources. The paper concludes that it is necessary to establish well-structured water-use data and employ more advanced forecasting methods if sound future decisions regarding water balance are expected to be made. In order to realize Beijing Municipality's full urban water conservation potential, it is suggested that a comprehensive and integrated long-term conservation program be implemented, which is technically feasible and economically justified, to conserve water consistently for many years.
The privatisation debate on water services in the Netherlands: public performance of the water sector and the implications of market forces
Authors: Kuks Stefan M.
Published: May 2018

Legally adopted in France and the UK, privatization of water services is still vigorously debated in the Netherlands. Advocates of privatization believe it is the best way to save on utility costs and to increase their transparency. Opponents believe that the Dutch water sector already provides high quality services for low prices, including an additional public performance that is expected to be excluded in a free market. The author argues that the performance of water service providers should not be assessed only in terms of efficiency, but in terms of the effects on the entire water system as well as the protection of small customers. It is quite possible that without privatization, a public agency could also improve its efficiency and become more competitive in relation to other service providers. Privatization seems to be more a matter of political ideology (based on a belief that the public sector operates inefficiently) than a matter of hard facts. The success of privatization depends at least on the performance of a complementary public regulatory regime. The question should not be whether the public or the private sector performs better hypothetically, but how the actual performance regarding public goods and services can be improved.
Traditional and novel reservoir management techniques to enhance water quality for subsequent potable water treatment
Authors: Bayley R. , Ta C.T. , Sherwin C.J. , Renton P.J.
Published: May 2018

Thames Water treats approximately 2800MI/d of water originating mainly from the lowland rivers Thames and Lee for supply to over 7.3 million customers, principally in the cities of London and Oxford. Most of the river water sources are stored in bank-side, pumped, storage reservoirs prior to treatment for potable use. Storage reservoir sizes vary and typical theoretical retention times lie between a few days to several weeks or months. During storage the riverine biota is largely replaced by lacustrine taxa which can cause problems for subsequent water treatment, particularly filtration. Recent concerns about cyanobacterial toxins has heightened interest in reservoir management. This paper reviews aspects of Thames Water's research, design and operating experiences of managing eutrophic, algal rich, reservoir stored, lowland water. Areas covered include experiences of optimising reservoir water quality to both control algal productivity and to aid subsequent potable water treatment. Traditional reservoir management techniques are reviewed as is research into biomanipulation. Whilst changes in reservoir water quality using these techniques have been marked, actual retention time and quality changes have traditionally been difficult to predict. Computational fluid dynamic (CFD) modelling has been used successfully to substantially increase retention and subsequent changes to water quality. Information from CFD modelling may also be used to reduce risks from protozoan parasites such as Cryptosporidium and Giardia.
Removal of ammonia by natural clay minerals using fixed and fluidised bed column reactors
Authors: Çelik M.S. , Özdemir B. , Turan M. , Koyuncu I. , Atesok G. , Sarikaya H.Z.
Published: May 2018

A series of fixed and fluidised bed ion exchange column runs were conducted to identify the ability of natural clay minerals, sepiolite and clinoptilolite, to remove ammonia from a contaminated drinking water reservoir. Ion exchange column tests using both fixed and fluidised bed were initially carried out with synthetic water composed of NH4Cl. Breakthrough curves as a function of flow rate, particle size, and initial ammonia concentration reveal that sepiolite does not have as high ion exchange capacity as clinoptilolite but maintains a steady adsorption up to higher bed volumes. The adsorption capacity was modified by using regeneration cycles at both acidic and alkaline pH. Furthermore, fluidised bed runs with clinoptilolite utilising water and air as fluidiser resulted in inferior results compared to those of fixed bed runs. This was respectively ascribed to the presence of ammonia in the circulating water and competition of exchangeable ions released in water and the ability of air to adsorb nitrogen. Tests conducted with natural raw water contaminated with sewage indicated that clinoptilolite adsorbs ammonia the same as the synthetic water. Regenerated clinoptilolite is capable of removing ammonia from both synthetic and actual raw water at a much higher rate than the untreated clinoptilolite.
Evaluation of the low pressure RO and NF membranes for an alternative tyreatment of Buyukcekmece Lake
Authors: Koyuncu I. , Yazgan M. , Topacik D. , Sarikaya H.Z.
Published: May 2018

The recent development of new generation LPRO and LPNF membranes has received attention for application in the field of wastewater and water treatment through an increasingly stringent regulation for drinking water purposes and water reclamation. This paper presents the pilot scale membrane separation studies on Buyukcekmece Lake in Istanbul with low pressure reverse osmosis (LPRO) and low pressure nanofiltration (LPNF) membranes. The application to treatment of anionic and cationic pollutants (Na+, Mg2+, Ca2+, Cl–, SO42–, NO3–) has been investigated as a function of transmembrane pressure and recovery rate under very low pressure range (3, 4, 5, and 6 bars). Flux value increased with increasing pressure and the membrane type of TFC-S gave the highest fluxes. The rejections of ions were increased with transmembrane pressure for two types of membranes. TFC-HR membrane rejection performance was better than the TFC-S membrane for all anionic and cationic pollutants. As recovery rate rises, the rejections were decreased.
Change in the water quality of industrial channels due to resuspension of sediments contaminated with heavy metals
Authors: Degtiareva A. , Elektorowicz M.
Published: May 2018

Industrial channels were used extensively during the two previous centuries and have become heavily contaminated. This study investigates possible water quality changes in the Lachine Canal (Montreal) due to the release of heavy metals (Cd, Ni, Zn and Pb) into the water column during resuspension of anoxic sediments subjected to potential remediation. This release can be initiated by dredging activities for sediment removal. Equilibrium in the water from the Lachine Canal has been calculated using the program EQUILIB from the software FACT. The speciation of heavy metals in the water column was calculated with and without a solid phase before and after possible dredging. Speciation of heavy metals in pore water of anoxic sediments has been calculated, taking into account that corresponding sulfides are the solid phases controlling their solubility. The concentration of heavy metals under anoxic conditions considered could decrease by 8 orders of magnitude. The impact of various scenarios in the area of concern was reviewed from an ecotoxicological perspective. Dredging can possibly change the redox and acid–base conditions in the water column. The impact of dredging will be less if sediments contain calcium. Dredging can lead to an increase in the concentration of heavy metals in the water column and a change of metal speciation.
Effects of pre-ozonation and selected advanced water treatment processes on Mount Seymour impoundment water
Authors: Bonneville C. , Smith D.W.
Published: May 2018

In May 1999, a project using a dissolved air flotation (DAF)/ozone/filtration pilot plant was started to study the effects of pre-ozonation on the flocculation of particles and removal of organic matter in an advanced treatment process. Results indicate that small doses of ozone pre-ozonation slightly improve the flocculation of particles and their subsequent removal in the DAF unit when used in conjunction with alum or PACl. However, it was found that high ozone doses impeded flocculation. More significant is ozone's benefit for the removal of UV-absorbing organic matter. The study also found that DAF is very effective at removing turbidity causing particles and colour from the water, thereby improving filter performance.
Ozone mass transfer in water treatment: hydrodynamics and mass transfer modeling of ozone bubble columns
Authors: El-Din M.G. , Smith D.W.
Published: May 2018

Most of the mathematical models that are employed to model the performance of bubble columns are based on the assumption that either plug flow or complete mixing conditions prevail in the liquid phase. Although due to the liquid-phase axial dispersion, the actual flow pattern in bubble columns is usually closer to being mixed flow rather than plug flow, but still not completely mixed flow. Therefore, the back flow cell model (BFCM), that hypothesises both back flow and exchange flow to characterise the liquid-phase axial dispersion, is presented as an alternative approach to describe the hydrodynamics and mass transfer of ozone bubble columns. BFCM is easy to formulate and solve. It is an accurate and reliable design model. Transient BFCM consists of NBFCM ordinary-first-order differential equations in which NBFCM unknowns (Yj) are to be determined. That set of equations was solved numerically as NBFCM linear algebraic equations. Steady-state BFCM consists of 3 × NBFCM non-linear algebraic equations in which 3 × NBFCM unknowns (qG,j, Xj, and Yj) are to be determined. Those non-linear algebraic equations were solved numerically using Newton–Raphson technique. Steady-state BFCM was initially tested using the pilot-scale experimental data of Zhou. BFCM provided excellent predictions of the dissolved ozone profiles under different operating conditions for both counter and co-current flow modes.
Experience in controlling Asellus aquaticus in water distribution systems
Authors: Oleszkiewicz A. , Geringer d'Oedenberg M. , Chapman J.
Published: May 2018

Asellus aquaticus is one of the nuisance organisms found in water distribution systems. Case studies of operations aimed at control of this crustacean and its disinfestation, carried out in two water distribution networks: in Pevensey Bay (Eastbourne, UK) and in Gdansk (Poland), are presented. Raw water reservoir receiving surface water was the source of infestation in Pevensey Bay. In Gdansk A. aquaticus probably penetrated the water distribution system with surface water getting into a leaky collecting well receiving groundwater from a chalk aquifer. The presence of organic matter in water entering the systems seemed to favour the infestation. Chemical treatment with pyrethrins (Pevensey Bay) and peracetic acid/hydrogen peroxide preparation (Gdansk) was used. The concentration of pyrethrins was 10 (g/dm3 and the average dose of peracetic acid was 4 mg/dm3. Both chemical treatments were found quite effective, however, some sections of the (much larger than Pevensey Bay) distribution network in Gdansk were not completely cleaned of the infestation.
Pipe material and water quality in a holistic view
Authors: Hedberg T.
Published: May 2018

The new trends in societies towards sustainable development have necessitated a new way of thinking regarding water treatment, the distribution of drinking water and wastewater treatment. A process of implementing new European water directives is ongoing and the consequences and need for coordination of these changes are discussed. Raw water qualities, water treatment technology and drinking water quality have impacts on water quality deterioration in the distribution networks that negatively affect the possibilities for recycling sewage sludge containing valuable nutrients. Measures for coping with these issues are discussed in general terms and suggestions for future strategies and research activities are given.
Structural design of pressure pipes
Authors: Bjorklund I.
Published: May 2018

There exist various methods for structural design of buried pressure pipes. However, it must be remembered that sophisticated design methods needs a significant supervision of the construction work to be reliable. The need for detailed calculations varies for different materials. Ductile iron (DCI) pipes have high strength properties and for most DCI pipe installations a design check against EN 545 is fully sufficient as regards the structural design. Glass fibre reinforced polyester (GRP) pipes have a limited strainability and are thus highly dependent on the quality of the installation work. It is recommendable to check that the combined strain of the load cases which the pipe shall be designed for does not exceed the allowable strain for the pipe material. Polyethylene (PE) and Polyvinylchloride (PVC) pipes are flexible pipes with a high strainability. The allowable working pressure for these pipes will normally be determined by the PN class and the operating temperature and the need for structural design calculations is limited. It is interesting to note that PE pipes which have the lowest strength properties of all of the above mentioned materials have the lowest failure rate. The latter shows that it is not just the tensile strength, but other factors such as strainability and corrosion resistance which affect the structural performance of buried pipelines.
Pipe material selection in drinking water systems - a conference summary
Authors: Elfström Broo A. , Berghult B. , Hedberg T.
Published: May 2018

A review is made of the oral presentations held at the conference “Pipe Material Selection in Drinking Water Distribution Systems - Sustainable Drinking Water Distribution Management”, held in Göteborg, Sweden on 5-6 September 2000. The topics discussed were: processes in the distribution network (microbiological activity and corrosion), water treatment and corrosion control, pipe material selection and structural design, and also the standardisation work within the European Union.
Assessing pathogen removal efficiency of microfiltration by monitoring membrane integrity
Authors: Hong S.K. , Miller F.A. , Taylor J.S.
Published: May 2018

This study was conducted to investigate the ability of various methods of monitoring membrane integrity to respond to changes in actual membrane integrity imposed by the compromised fibers within the microfiltration unit. In addition, the pilot-scale MF unit was challenged with high concentrations of coliform, Cryptosporidium, and spore, in order to assess the pathogen removal capability of microfiltration. A correlation between the integrity tests and microbial challenge data was also made. The integrity tests investigated in this study were pressure decay and diffusive air flow tests (direct integrity tests), and turbidity and particle counting (indirect integrity tests). Both pressure decay (PDT) and diffusive air flow (DAF) tests were sensitive enough to detect one damaged fiber out of 66,000. The extent of fouling did not affect the sensitivity of the PDT and DAF, showing that PDT and DAF tests are a simple, reliable means to monitor membrane integrity under field conditions. Indirect integrity monitoring using turbidity and particle counting, however, responded poorly to changes in membrane integrity. Microbial challenge study demonstrated that microfiltration was capable of removing various pathogens including Cryptosporidium, at the level required by drinking water regulations, under even adverse operating conditions. Finally, PDT and DAF tests showed a better correlation with actual microbial removal efficiency of microfiltration than turbidity and particle counting. The turbidity and particle counting grossly underestimated the removal of pathogen larger than MF membrane pore size due to poor sensitivity.
Dynamic testing of water treatment coagulants
Authors: Gregory J. , Rossi L.
Published: May 2018

Pre-polymerised inorganic coagulants, such as polyaluminium chloride (PAC) have several advantages over conventional aluminium and iron salts. However, their mode of action is not fully understood and progress in this area has been made largely by empirical approaches. In this preliminary study we have followed the dynamics of flocculation of model clay/humic acid suspensions following the addition of three different coagulants: aluminium sulphate and two commercial PAC products. Experiments were conducted using controlled stirring rates in a modified jar test procedure, in which the formation and break-up of flocs could be monitored continuously by a flow-through optical technique. The results show significant differences in the behaviour of the coagulants and one of the PAC samples gives much larger and stronger flocs. Further experiments along these lines should help to elucidate the mode of action of different forms of coagulant and to aid in their selection for specific applications.
Hydrogen peroxide/iron oxide-induced catalytic oxidation of organic compounds
Authors: Gurol M.D. , Lin S-S.
Published: May 2018

This paper describes a novel heterogeneous catalytic oxidation process involving the use of hydrogen peroxide ( H2O2) with granular size iron oxide particles (FeOOH) in aqueous phase. The generation of hydroxyl radical (OH•) in the process is demonstrated through the use of a probe chemical, n-chlorobutane (BuCl). Based on the experimental evidence, it is concluded that the OH•, which is produced through the interaction of H2O2 with the surface sites, reacts with solutes adsorbed on the iron oxide surface, causing oxidation of the organic compounds. The generation rate of OH• increases slightly with increasing pH in the range of 5-9. The oxidation rate of BuCl by OH• is relatively insensitive to the pH and the level of bicarbonate ion in subject water due to low affinity of bicarbonate for the surface. Phosphate, on the other hand, inhibits the oxidation rate by preferential adsorption on the surface. This new process provides a viable alternative to the existing oxidation technologies, especially when water has high alkalinity and/or it is desired to oxidize target compounds that have high affinity for the surface selectively.
Improving the performance of dead-end ultrafiltration systems: comparing air and water flushing
Authors: Kennedy M. , Siriphannon S. , van Hoof S. , Schippers J.
Published: May 2018

A cleaning protocol that effectively removes fouling from hollow fiber UF systems without excessive use of chemicals, product water or (long) down time is needed. Cross flushing with UF feed water has been reported to increase the net flux of hollow fiber systems by reducing the frequency of backwashing, the consumption of permeate and the system down time. In this study, the flux restoration achieved in a vertical and horizontal UF system employing an intermittent water and water/air cross flush were compared. The flux restoration in the vertical UF system was not improved by the addition of air to the water flush and a maximum flux restoration of 82% was achieved, irrespective of the presence of air. Similarly, in a horizontal ultrafiltration system, a maximum flux restoration of 82% was also achieved with a water flush (v = 1.63 m/s). However, the addition of air to the water flush decreased the flux restoration to 40% at the highest water/air ratio (33% air). Low flux restoration in the horizontal system was attributed to residual air in the module after cross flushing. Flushing with water alone (v = 1.63 m/s) yielded a wall shear stress of 16 Pa compared with 130 Pa and 279 Pa in the liquid film surrounding the air slugs in the horizontal and vertical UF system, respectively, with a water/air ratio of 2:1. Despite the high shear force on the cake layer accumulated when air was added to the system, the maximum flux restoration was 82% both with and without air. This was attributed to the fact that it was the filtration mechanism and not the shear force on the cake layer that limited flux restoration during cross flushing. To improve the flux restoration that can be achieved by the cross flushing process, the filtration mechanism must be manipulated to minimize blocking filtration and induce cake filtration from the beginning of each filtration cycle.
Advanced water treatment system using ozone and ozone resistant microfiltration module
Authors: Hashino M. , Mori Y. , Fujii Y. , Nakatani K. , Hori H. , Takahashi K. , Motoyama N. , Mizuno K. , Minegishi T.
Published: May 2018

In order to achieve an efficient and economical advanced drinking water system, the relationship between operating conditions, membrane filtration flux and water qualities was examined by using a pilot plant consisting of ozonation facility, ozone resistant microfiltration (MF) module and granular activated carbon (GAC) tower. It was found that keeping residual ozone of more than 0.3 mg/L on the membrane surface is necessary in order to obtain a high membrane filtration flux. Withy ozone dosage of 3 mg/L by ejector and filtration by dead-end mode, this new system provided a high membrane filtration flux of more than 5 m3/m2/day. Quality of the produced water from the GAC tower was meeting the drinking water standard.
Development of a membrane integrity monitoring strategy for the UF/RO Heemskerk drinking water treatment plant
Authors: Kruithof J.C. , Kamp P.C. , Folmer H.C. , Nederlof M.M. , van Hoof S.C.J.M.
Published: May 2018

At the Heemskerk water treatment plant of N.V. PWN Water Supply Company North Holland the first full scale integrated membrane system in the Netherlands is realized. The 20 Mm3/year (15 MGD) ultrafiltration (UF)/reverse osmosis (RO) plant servicing IJssel Lake water has been in operation since the second half of 1999. Disinfection is a major objective of the direct surface water treatment plant without chemical disinfection. After UF indicator organisms such as E. coli and Clostridia spores were absent. Integer UF membranes removed MS-2 phage spikes completely (<5.4 log), severely compromised membranes removed 2.7 log only. RO showed a high although incomplete removal of MS-2 phages (up to 4.8 log). Therefore integrity monitoring is a critical issue. Before installation, vacuum testing was applied with a criterion of 10 kPa/min. Many standard modules failed to pass the test. During operation UF is monitored by 1 μm particle counting with 0.05 μm particle counting as a quality control. A 3 log removal can be established. At this moment for RO conductivity measurement is applied enabling a 2 log removal monitoring. Short term monitoring of conductivity will be replaced by sulfate, increasing the monitoring range by 1 log unit. The total monitoring range of 5-6 log units easily satisfies the maximum disinfection requirement for the membrane steps for viruses of 3.6 log. To determine a wider range of disinfection requirements PWN together with Norit Membrane Technology developed the Spiked Integrity Monitoring (SIM®) System. Spiking with 14000 PAC particles/ml combined with 1 μm particle counting increased the potential for log removal monitoring of UF to 5.8 log units. Additionally PAC particle spiking increased the potential to detect UF fiber compromising. During the first 200 days of full scale operation, system performance is excellent. Membrane integrity control is very satisfactory and SIM®-System integrity control has proved to be a valid technique to establish a broader range of required inactivation capacities.
Water reclamation with membrane bioreactors
Authors: Gagliardo P. , Adham S. , Merlo R.P. , Trussell R.S. , Trussell R.R.
Published: May 2018

The City of San Diego was awarded a grant from the Bureau of Reclamation to investigate the feasibility of using Membrane Bioreactors (MBRs) for water reclamation. Based on the findings of the first phase of the project (Adham et al., 1998), the project team concluded that a parallel comparison of commercially available MBR systems needed to be evaluated at pilot-scale. Two submerged MBR systems were evaluated at the Aqua 2000 Research Center in Escondido, California. The project was designed to evaluate the MBR performance treating municipal wastewater and the feasibility of using the MBR permeate as a feed source for thin film composite reverse osmosis (RO) membranes. The first part of the project was dedicated to operating both MBRs in a nitrification and denitrification mode. After completion of Part 1 of the project, both MBR systems were retrofitted and operated in a nitrification only mode. Throughout both parts of the study, the effluent from each MBR was fed to two separate, single stage RO pilot systems. Both MBR systems showed high BOD removal with values below the detection limit, and significant TOC reduction. The effluent turbidities from the MBRs were consistently less than 0.1 NTU. Both MBRs also produced a high quality effluent that could be used by thin film composite RO membranes with minimal fouling.
Enhancing the particle removal efficiency of a drinking water treatment plant by membrane filtration
Authors: Hagmeyer G. , Kiepke O. , Dautzenberg W. , Gimbel R.
Published: May 2018

In the first step of the project funded by the German Federal Ministry for Education and Research (BMBF) three UF pilot systems (about 10 m3/h) were evaluated for drinking water treatment of reservoir water. In the second step a 150 m3/h pilot plant with 12 6 m long pressure vessels was installed in the waterworks of Roetgen. One of the unique features of the pilot is, that the inlet and outlet flows of every pressure vessel are monitored. Further on a particle counter is installed. With this particle counter the filtrate of every pressure vessel can be monitored automatically by switching magnetic valves.
Combined air-water flush in dead-end ultrafiltration
Authors: Verbeck J.Q.J.C. , Worm G.I.M. , Futselaar H. , van Dijk J.C.
Published: May 2018

Dead-end ultrafiltration has proven itself as a technique for reclamation of backwash water of sand filters and as a pre-treatment step for spiral wound reverse osmosis. A direct result of dead-end filtration is a decreased flux 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 research has started into the fundamentals of the combined air- and water-flush. First a series of experiments has been carried out to determine the different flow patterns, followed by experiments to determine which air- and water-velocities give the best cleaning. Finally head loss experiments have been done to get information about the energy dissipated in the system. The results of the head loss experiments have been compared to the theoretical head loss calculated with the theory of heterogeneous two-phase flow.
Development of a prototype treatment works management based on real-time process simulation
Authors: Butt G. , Head R.
Published: May 2018

On water treatment SCADA (supervisory control and data acquisition) systems, the vast majority of reported values are not utilised or viewed unless it is in response to a raised alarm. There is therefore clear benefit in developing a system that uses existing information for proactive management of treatment plants. This paper outlines the development of a prototype system featuring real-time simulations, an alarm handling facility, an instrument analyser and “user” defined simulations. The system offers benefits through proactive WTW operation, de-manning, risk reduction, reduced maintenance and chemical costs and as a training tool. Also discussed are factors that may influence the implementation of such a system and also future development possibilities.
Prediction of breakthrough of pesticides in GAC-filters and breakthrough of colour in ion-exchange-filters
Authors: Heijman S.G.J. , Siegers W. , Sterk R. , Hopman R.
Published: May 2018

Adsorption columns are widely used in drinking water treatment to improve a number of water quality parameters. Granular activated carbon filtration (GAC) can be used to decrease the concentration of DOC, colour, taste, odour and pesticides. Columns filled with ion-exchange resins are used to remove colour, nitrate and DOC. The regeneration frequency of these types of filters depends strongly on the natural water quality. Especially the DOC-concentration and DOC-composition determines the efficiency of the processes. Because pilot-plant experiments with realistic contact-times will last for more than a year (for GAC) there is a need for a prediction of breakthrough based on shorter and less expensive laboratory experiments. The available models are not accurate enough because the exact parameters are not available. In batch experiments with natural water, with realistic (low) pesticide concentrations and the full grain size of the adsorbent the adsorption parameters are measured in an independent experiment. With the parameters obtained with these experiments an accurate prediction of the breakthrough curve is possible.

With the same parameters predictions of breakthrough curves are calculated under different process conditions. The possibilities of process optimisation can reduce the investment costs for new full-scale plants.
Improving the efficiency of rapid sandfilters by adding small amounts of ferric salts (βFe ≤ 0.1 mg·L-1)
Authors: Schick R. , Winzenbacher R. , Stabel H.-H. , Jekel M.
Published: May 2018

Improved removal of suspended matter during the treatment of water from Lake Constance has been achieved by pre-ozonation (βO3 = 1 mg·L-1 corresponding to 0.8 mg O3/mg DOC) and the addition of small quantities of iron salts (βFe≤0.1 mg·L-1; “Fe(III)-assisted filtration”) followed by rapid sand filtration. As shown by investigations on a large-scale installation (bypass mode) over several years, this procedure reliably reduces particulate matter in the water by about 3 orders of magnitude in long-term use. However, the high efficacy of Fe(III)-assisted filtration cannot be explained on the basis of known coagulation mechanisms (adsorption-charge neutralization, co-precipitation). Instead, the essential step was found to be the conditioning of the filter medium by coating it with colloids containing Fe(OH)3, and this “Fe coating” process only occurs in the presence of alkaline earth cations (especially Ca2+). According to further experiments, the enhanced solid-liquid separation was ultimately traced to chemical interactions such as the formation of calcium-NOM bridges between the iron hydroxides and other solids.
An evaluation of high rate filtration using particle counting and turbidimetry for low turbidity waters
Authors: Schneider O.D. , Nickols D. , VandeVenter L. , Leggiero S.
Published: May 2018

A pilot-scale evaluation of high rate filtration using both on-line turbidimeters and optical on-line particle counters was performed. At turbidities approaching the detection limit of the equipment (less than 0.05 ntu), particle counting proved to be a much better indicator of filtration performance. In addition, at these low turbidities, large changes in particle counts (one to two orders of magnitude) would register with only minor changes in turbidity (less than 0.02 ntu).
Innovation of conventional water treatment techniques in effluent reclamation
Authors: Kramer J.F. , van der Graaf J.H.J.M. , van der Velde R.T. , van't Oever E. , van Kessel A.A.L.
Published: May 2018

For reclamation of waste water treatment plant (wwtp) effluent, conventional water treatment techniques used in drinking water supply may be suitable. Earlier studies and experiments showed that the most promising cost-effective conventional techniques to polish wwtp effluent are coagulation and rapid multi-media filtration (direct filtration). In the past 4 years these techniques were tested in long term experiments on pilot scale (5-10 m3/h) at several waste water treatment plants in The Netherlands. For successful application of direct filtration for the removal of suspended solids and colloidal material careful consideration is needed with the coagulation conditions. However additional treatment is required to meet the standards for household and process water with respect to ammonium, colour, pathogens and (biodegradable) organic substances.
The removal of Cu (II), Cd (II), Ni (II) and Pb (II) from dilute aqueous solution by a poly(acrylic acid) flocculant and its cross-linked analogue
Authors: Morlay C. , Mouginot Y. , Cromer M. , Vittori O.
Published: May 2018

The possible removal of copper (II), cadmium (II), nickel (II) and lead (II) from dilute aqueous solution by complexation with poly(acrylic acids) was investigated. The binding properties of two hydrosoluble poly(acrylic acids) of high molecular weight (which make them representative of synthetic flocculants used in the water treatment field; Mw = 2.5 × 105 and 3 × 106 g mol-1) and of an insoluble cross-linked analogue were examined. Potentiometric titrations were carried out, first, to determine the acid-base properties of both polymers and, secondly, to determine the stability constants of the MA and MA2 complex species formed. Metal complexation was also studied using differential pulse polarography. The complexing capacity of each polyacid for the metal ions under study was determined at pH 6.0, 5.0 and 4.0 and the ionic strength was 0.1 or 1.0 mol l-1. The conditional stability constants were estimated assuming that only 1:1 complex species were formed. The results obtained by both methods agree and are complementary. It appeared that stability constants increased in the following order, depending on the metal ion : Ni (II) << Cd (II) < Cu (II) < Pb (II). The hydrosoluble polyacid was able to fix up to 6.3 mmol Pb (II)/g while the insoluble cross-linked analogue was able to fix up to 4.8 mmol Pb (II)/g.