bluuebunny/crossref_metadata_2025 huggingface dataset:
Serological responses to Cryptosporidium antigens among women using riverbank-filtered water, conventionally filtered surface water and groundwater in Hungary
Authors: Frost Floyd , Muller Tim , Craun Gunther , Mihály Kádár , György Berencsi , Calderon Rebecca
Published: May 2018

We compared serological responses to Cryptosporidium parvum antigens using surplus sera from females undergoing routine screening for pregnancy from three counties in Hungary where bank-filtered surface water, conventionally filtered and disinfected surface water, and groundwater from either a karst or confined aquifer are commonly used for drinking water. The primary purpose was to determine whether the prevalence and intensity of serological responses, indicators of prior Cryptosporidium infection were similar for these populations. Women using groundwater from a confined aquifer had significantly lower mean serological responses for both the 15/17-kDa and 27-kDa (p<0.0001) antigen groups than women using conventionally filtered and disinfected surface water or karst well water. This is suggestive of less frequent infections. Women using bank-filtered water also had lower mean responses for both antigen groups. Among women using bank-filtered water, the mean intensity of response for both antigen groups was almost one-third of the mean response observed for women using conventionally filtered and disinfected surface water. These findings suggest that riverbank filtration may be an effective alternative to conventional treatment for reducing Cryptosporidium exposures and infection from surface drinking water sources.
Deficiencies in drinking water distribution systems in developing countries
Authors: Lee Ellen J. , Schwab Kellogg J.
Published: May 2018

Rapidly growing populations and migration to urban areas in developing countries has resulted in a vital need for the establishment of centralized water systems to disseminate potable water to residents. Protected source water and modern, well-maintained drinking water treatment plants can provide water adequate for human consumption. However, ageing, stressed or poorly maintained distribution systems can cause the quality of piped drinking water to deteriorate below acceptable levels and pose serious health risks. This review will outline distribution system deficiencies in developing countries caused by: the failure to disinfect water or maintain a proper disinfection residual; low pipeline water pressure; intermittent service; excessive network leakages; corrosion of parts; inadequate sewage disposal; and inequitable pricing and usage of water. Through improved research, monitoring and surveillance, increased understanding of distribution system deficiencies may focus limited resources on key areas in an effort to improve public health and decrease global disease burden.
A pilot randomized, controlled trial of an in-home drinking water intervention among HIV+ persons
Authors: Colford John M. , Saha Sona R. , Wright Catherine C. , Hubbard Alan , Eisenberg Joseph N.S. , Wade Timothy J. , Vu Mai , Charles Sandra , Jensen Peter , Levy Deborah A.
Published: May 2018

Although immunocompromised persons may be at increased risk for gastrointestinal illnesses, no trials investigating drinking water treatment and gastrointestinal illness in such patients have been published. Earlier results from San Francisco suggested an association (OR 6.76) between tap water and cryptosporidiosis among HIV+ persons. The authors conducted a randomized, triple-blinded intervention trial of home water treatment in San Francisco, California, from April 2000 to May 2001. Fifty HIV-positive patients were randomized to externally identical active (N = 24) or sham (N = 26) treatment devices. The active device contained a filter and UV light; the sham provided no treatment. Forty-five (90%) of the participants completed the study and were successfully blinded. Illness was measured using ‘highly credible gastrointestinal illness’ (HCGI), a previously published measure. There were 31 episodes of HCGI during 1,797 person-days in the sham group and 16 episodes during 1,478 person-days in the active group. The adjusted relative risk was 3.34 (95% CI: 0.99–11.21) times greater in those with the sham device. The magnitude of the point estimate of the risk, its consistency with recently published observational data, and its relevance for drinking water choices by immunocompromised individuals support the need for larger trials.
Effect of precipitation on seasonal variability in cryptosporidiosis recorded by the North West England surveillance system in 1990–1999
Authors: Naumova Elena N. , Christodouleas John , Hunter Paul R. , Syed Qutub
Published: May 2018

The goal of this study was to examine temporal and spatial variability of reported cryptosporidiosis in 15 health authorities in the North West of England using regression modelling. We also examined the role of precipitation as a driving factor for seasonal variation. We separated the time series of the reported cryptosporidiosis into two processes: an endemic process and an epidemic process, and examined the spatial variability of each of these processes. In the North West region of England we observed a strong seasonal pattern that consists of two waves, spring and autumn, during which the weekly rates exceeded the endemic level 3.5 and 3 times, respectively. Health authorities with the high endemic cryptosporidiosis incidence and well-pronounced seasonal patterns exhibited a significant increase in rates of cryptosporidiosis associated with increased precipitation. The endemic level and the magnitude of epidemic peaks were inversely related, which might be indicative of multiple exposures to the pathogen in these localities and the development of some partial immunity.
Escherichia coli control in a surface flow treatment wetland
Authors: MacIntyre M. E. , Warner B. G. , Slawson R. M.
Published: May 2018

A field experiment showed that numbers of Escherichia coli declined significantly when floating Lemna spp. plants were removed to create open water areas in a typical newly constructed surface flow treatment wetland in southern Ontario. It is suggested that E. coli declined immediately after Lemna removal because the Lemna was shading the water column from penetration by natural UV radiation, it was providing favourable attachment sites for the E. coli, and it was not allowing effective free exchange of oxygen from surface winds to the water column to maintain high enough dissolved oxygen supplies for predator zooplankton populations. Operators of wetland systems must have the specialized skills required to recognize the cause and the appropriate maintenance requirements to maintain efficient operation of such unconventional systems should E. coli numbers increase during the course of operation.
A case–cohort study to investigate concomitant waterborne outbreaks of Campylobacter and gastroenteritis in Söderhamn, Sweden, 2002–3
Authors: Martin Stephen , Penttinen P. , Hedin G. , Ljungström M. , Allestam G. , Andersson Y. , Giesecke J.
Published: May 2018

Increased domestic, laboratory confirmed, Campylobacter notifications were reported in Söderhamn municipality, December 2002 and January 2003. Concurrently, during preliminary investigations a large outbreak of acute gastroenteritis was detected. Simultaneously, two studies were completed to identify risk factors for infection with Campylobacter and acute gastrointestinal infection (AGI): (1) a case–cohort study using Campylobacter cases (N =101) with a large random sample from the municipal population as referents (N=1000) and (2) a retrospective cohort study for the outcome AGI using the same sample. A postal questionnaire was used to collect demographic, clinical, water and food consumption data. Measures of association (risk ratio (RR), odds ratio (OR)) and 95% confidence intervals (CI) were calculated. Stool, environmental and water samples were tested by standard methods at Gävle Hospital and SMI laboratories respectively. In the case–cohort study, Camplylobacter cases were more likely than referents to consume communal water (OR=12.6 (95% CI 1.7–92.3)). In the cohort study, risk of gastroenteritis was 2.3 times higher in those who consumed water (AR=27.3%) than others (AR=12%). Risk of illness was associated with the amount of water consumed in both studies. Campylobacter was detected in stools and Escherichia coli (E. coli) from routine communal water (CW) samples. Results suggest both Söderhamn outbreaks of Campylobacter and AGI were associated with consumption of CW. The method used strengthened epidemiological evidence and was efficient in the use of time and resources.
The case for the rope-pump in Africa: A comparative performance analysis
Authors: Harvey P. A. , Drouin T.
Published: May 2018

The conventional handpump is the most popular technology choice for improved potable water supplies in rural sub-Saharan Africa. To date, however, it has failed to deliver satisfactory levels of sustainability, largely due to inadequate maintenance capacity. An alternative option to standardised imported handpumps is the locally manufactured rope-pump, which is considerably cheaper and easier to maintain but has been rejected in the past due to fears of impaired water quality. This paper presents the key aspects of a study in northern Ghana which compared the performance of rope-pumps with that of conventional handpumps, to determine whether or not the rope-pump provides a viable alternative for community water supplies across the sub-continent. User interviews, sanitary surveys, water quality analyses and technical performance measurements were used to develop a comparative performance analysis for the two pump types. The findings of the study indicated that the rope-pump out-performed the conventional handpump on the majority of counts and that, contrary to widespread perceptions, there was no significant difference between pump types with respect to the impact on microbiological water quality. Consequently, the rope-pump provides a significant technological opportunity to improve water supply sustainability in Africa.
The hydrosocial contract theory and the Lesotho Highlands Water Project
Authors: Meissner Richard , Turton Anthony R.
Published: May 2018

The hydrosocial contract theory, as a new theory in water discourse, should be investigated. The theory postulates that a number of transitions occur in society concerning the development of water resources and that these transitions can lead to a number of social instabilities. The Lesotho Highlands Water Project (LHWP) is a manifestation of the hydrosocial contract in that it was developed during transitions, not only with respect to water resources development but also along international political faultlines. These faultlines were, at times, the most influencing variables that impacted on the implementation of the LHWP.
Integrated water management in the South Pacific: policy, institutional and socio-cultural dimensions
Authors: Keen Meg
Published: May 2018

As scarce water supplies in urban environments come under increasing pressure, water managers are forced to widen technical analyses to incorporate issues related to water governance. The concept of integrated water management has been developed to highlight that social, institutional and economic issues, in addition to technical and ecological considerations, need to be considered concurrently. In this paper, the integrated water management framework is used to highlight some of the social and institutional issues of concern to water management in the South Pacific. A case study of Suva, the rapidly growing capital of Fiji, is used to illustrate the complexity of the management issues facing Pacific Island countries. It is argued that the trend toward more systemic management of water resources is a positive one, but in the case of the Pacific Island countries much better accounts of inter-agency communication, community education, public engagement, institutional coordination, water pricing and water monitoring are needed.
Dynamics of irrigation-poverty linkages in rural India: analytical framework and empirical analysis
Authors: Saleth R. Maria , Namara Regassa E. , Samad Madar
Published: May 2018

This paper makes a different, if not a unique, attempt at a quantitative evaluation of the multifarious linkages between irrigation and rural poverty by taking a system approach and using cross-section data pertaining to 80 agro-climatic sub-zones of India for two time points, i.e. 1984–85 and 1994–95. It develops first an analytical framework to depict the most important pathways and layers of irrigation–poverty linkages as mediated though three key systems: water system, agro-economic system and socio-economic and demographic system. These pathways and linkages are, then, translated into an econometric form in terms of a system of simultaneous equations defined by a set of irrigation-related, agro-economic, socio-economic and demographic variables. By estimating this system of equations in the context of the agro-climatic sub-zones of India for the two time points, this paper empirically evaluates the mechanics and dynamics of irrigation–poverty linkages. Based on an analysis of the empirical results, this paper concludes by identifying some of the analytical, methodological and policy issues crucial for understanding and promoting the overall poverty alleviation impacts of irrigation.
Considering the Water Poverty Index in the context of poverty alleviation
Authors: Sullivan Caroline , Meigh Jeremy
Published: May 2018

The Water Poverty Index (WPI), introduced by Sullivan, is an inter-disciplinary tool that integrates the key issues relating to water resources, combining physical, social, economic and environmental information associated with people's ability to get access to water and to use water for productive purposes. It is most relevant at the community or sub-basin scales. This paper is concerned not with the development or underlying methodology of the index, but with how it can best be applied in practice to generate useful data, and then how these data may be used to generate benefits, especially for poor people who suffer from inadequate access to water. WPI values would need to be generated over wide areas, and this would require substantial institutional development. To do this, the use of existing census procedures and the needs for simplified data collection are considered, and the idea of widespread data collection through schools is examined. A number of technical issues relating to implementation of the WPI are discussed, particularly how the different spatial scales inter-relate and how the assessment of the physical resource and the collection of social and economic data may be made compatible. Finally, we discuss how the WPI value can be used in practice, and some of the issues and problems that this presents.
Water poverty indicators: conceptual problems and policy issues
Authors: Molle François , Mollinga Peter
Published: May 2018

In the wake of a growing concern about both the unchecked rise of poverty and the local and global consequences of water scarcity, the relationships between water and poverty are the object of a sprawling literature. Indicators are presented as indispensable tools for informing and orienting policy-making, comparing situations and measuring performance. This paper first reviews different conceptions of water scarcity and shows the variety of associated causes. A brief look at the virtues and shortcomings of some of the indicators used in the development sector then serves to introduce a review of the major water-scarcity/poverty indicators found in the literature. The reasons for their popularity and vitality are critically examined, and the links between indicators and policy-making are discussed.
Defining water rights: by prescription or negotiation?
Authors: Molle Francois
Published: May 2018

Establishing water rights is an appealing measure, which conveys a sense of orderliness and rationality that contrasts with a situation of assumed wastage, environmental degradation and con.icts. Transferable entitlements increase economic efficiency, while providing a compensation mechanism. The paper distinguishes between formal rights de.ned through a bureaucratic process and flexible allocation rules designed through a gradual and continuous process of negotiation. It investigates the prerequisites, advantages and drawbacks of these two kinds of water rights, and examines how they apply to the specific natural and historical conditions of Sri Lanka. It concludes by showing that policy models must be tailored to the local situation and be based on what is feasible rather than on what is considered desirable.
Stakeholders' response to the private sector participation of water supply utility in Karachi, Pakistan
Authors: Ahmed N. , Sohail M.
Published: May 2018

Changes are proposed to improve urban water supply systems around the globe. Improvement in service delivery mechanisms, institutional efficiency, financial viability and acceptance by users are the key criteria for initiating and sustaining a change. To improve the situation of water supply in Karachi, Pakistan, advised by the World Bank, a private sector participation (PSP) strategy was formed during the 1990s. The strategy aimed to promote a gradual increase of PSP in water and sanitation services. The proposed project faced strong resistance from stakeholders, mainly civil society, leading to its suspension. Efforts are being made to revive the PSP and to make it acceptable to the stakeholders concerned. The paper documents and analyses the stakeholders response to the anticipated PSP process and the possible social and economic impacts. The study makes a contribution in the areas of participation and consensus building in the context of PSP. Willingness to negotiate continuously and even consideration of possible alternatives based on the changing situations are the key to any way forward for sustainable improvements.
The 2002 Water Law: its impacts on river basin management in China
Authors: Shen Dajun
Published: May 2018

Modern river basin management techniques are gaining popularity in China to effectively manage increasingly vulnerable water resources. China has several large river basins, with a variety of resource conditions and development challenges. River basins in China are facing aggravated water pollution, and development and management issues. In dealing with these issues, and in line with the evolution of modern concepts of river basin management, the 2002 Water Law of People's Republic of China for the first time defines river basin management institutions and functions, the legal status of river basin management organizations in China, and strengthens the administrative rights of river basin management organizations. However, although it is a good beginning, it is far from perfect. There are still several key issues which need to be addressed in the future, such as: function clarification, relationships between river basin management and jurisdictional management, participation, and coordination and integration of natural resources management.
Household responsiveness to water demand management incentives in Windhoek, Namibia
Authors: Sjömander Magnusson Therése
Published: May 2018

Water demand management is seen as a useful tool for curbing luxury water demand, improving efficiency and increasing awareness about water scarcity. In this paper, the response by households to pricing and information, as part of water demand management, in both the formal and informal areas of Windhoek is analysed. The results imply that the effectiveness of block tariffs is overestimated when applied to middle and high income areas. Instead urban lifestyle and accessibility to water dominates behavioural patterns at a certain consumption level. In addition, information about water scarcity was adapted among most households in the squatter areas.
Household preferences to water policy interventions in rural South Africa
Authors: Hope R. A. , Garrod G. D.
Published: May 2018

Water policy is often designed and implemented without negotiation with or participation from the intended beneficiaries. This is often the case in the implementation of global water policy initiatives that aim to benefit rural households in the developing world. Evidence of water policy responding to the locally defined preferences of the rural majority without improved water services is weak. Significant efforts have made to unpack quantity, quality and source attributes of domestic water supply to the least well-served populations in sub-Saharan Africa and Asia. This effort has been limited to evaluating individual attributes in relation to health, productivity and usage criteria rather than a ‘user evaluation’ of these attributes together. The advantage of the latter approach is that trade-offs between attributes can be estimated to provide parameters for each attribute and marginal rates of substitution between attributes. A choice experiment in rural South Africa examines the preferences of households to changes in domestic water sources, water quantity, water quality, stream-flow failure and productive uses of domestic water. Trade-offs in rural household domestic water preferences estimate welfare coefficients that provide a ‘user evaluation’ of water policy interventions. The findings provide defensible estimates of the magnitude and direction of the utility gain/loss from water attributes that allows a more evidenced-based understanding of rural households' preferences to water policy interventions.
Water institutional reforms in Chile
Authors: Hearnea Robert R. , Donosob Guillermo
Published: May 2018

This paper provides a review of the recent institutional changes observed in the water sector in Chile. This review is then used to reflect the Chilean experience in the light of the results concerning institutional change found in existing literature on both institutional economics in general and water institutional economics in particular. These results relate to factors explaining institutional change and the role of endogenous institutional features, such as path dependency and institutional linkages during the reform process. Against a brief description of the main features of the water sector in Chile, the paper provides an overview of Chilean water management institutions and the reforms process ongoing since the 1980s. The factors that motivated institutional changes in Chile's water management include ideology, transactions costs, interest-group behavior and path dependency. While the already observed institutional changes, such as the transferable water rights, water markets and urban water reforms, are all significant, further reforms are delayed by the deliberate legislative process required for changes as a result of the 1980 Constitution. Future water reforms in Chile, therefore, depend on a very difficult process of political reforms needed to change the 1980 Constitution and the 1981 Water Code.
The silent revolution in groundwater intensive use and its influence in Spain
Authors: Fornés Juan M. , Hera África la , Llamas M. Ramón
Published: May 2018

In the last half-century in most semi-arid or arid developed and developing countries, many aquifers have become intensively used. This means that the hydrogeological conditions may have changed, with groundwater storage being modified significantly. This intensive use has been performed mainly by millions of modest farmers with scarce public or governmental planning. This silent revolution has been market driven. The cost of groundwater abstraction is usually a small fraction of the value of the irrigated crop obtained. The benefits have been clear and important in most cases. In poor countries groundwater development has provided reliable drinking water supply and increased food security through irrigation, and consequently groundwater as become a relevant means of eradicating poverty. The impact of this groundwater development in developed countries is also significant but not yet well recognised. But sometimes, there are other associated negative effects. These sometimes have been utilised by certain lobbies to expand the hydro-myth of the unreliability (or fragility) of groundwater development, in order to continue to promote the construction of large hydraulic infrastructures.

In Spain, groundwater irrigation accounts for more than 50% of the total economic value of irrigated agricultural production, while it only consumes about 20% of the total volume of water. In spite of its benefits, groundwater has not been a significant part of Spanish water policy.
Sustainable use of water resources in agriculture in Beijing: problems and countermeasures
Authors: Wang Yan , Wang Hongrui
Published: May 2018

Beijing, the capital of China, is one of the most water-scarce metropolises in the world. The present water policies are leading to serious water scarcity in agriculture. The proportion of agricultural water to total water has been dropping continuously in Beijing in past years. The influence of water scarcity on grain yield and planting production value has been analyzed in this paper. The problems of ecological environment and rural social problems that arise from water scarcity are also discussed in the paper. Based on the above analysis, the paper gives some suggestions for alleviating the tension, such as developing water-saving agriculture, adjusting planting structure and properly developing sewage irrigation.
Governance, business models and restructuring water supply utilities: recent developments in Ontario, Canada
Authors: Bakker Karen , Cameron David
Published: May 2018

Many municipal governments are currently confronted with the need to restructure water supply systems. This paper examines how municipalities are restructuring water supply utility management in the province of Ontario (Canada), which has recently experienced significant and rapid legislative and regulatory reform in the water sector. The paper analyses restructuring in six different municipalities (Hamilton, Kingston, Peel, Peterborough, Toronto and York). It identifies six distinct business models adopted as an outcome of the restructuring process (delegated management to a private operator, corporatization of services provision, delegated management to a public operator, a municipal commission, a municipal ‘business unit’ and a municipal department) and examines the different approaches to governance adopted during the restructuring process. The case study is conceptualized through a discussion of the governance and restructuring challenges faced by municipalities. As municipalities are often confronted with a bewildering array of business models, governance frameworks and contract types when engaging in a review of restructuring options, the paper situates the analysis of the Ontario case within a general survey of business models for networked water supply. The paper concludes with a discussion of “lessons learnt” relevant to municipalities and higher orders of government when engaging in restructuring of networked water supply provision.
Strategic planning for urban sanitation—a 21st century development priority?
Authors: Tayler Kevin , Parkinson Jonathan
Published: May 2018

The provision of adequate environmental sanitation services to all inhabitants of urban areas in developing countries will not be achieved by the market or “self-help” action alone. There is a need for planning but this planning must be strategic in nature, focusing on the most important issues and allowing for the many uncertainties that are inherent in the current situation. The paper describes the field testing of a strategic planning process in India and subsequent efforts to explore ways of institutionalising the lessons learnt from this experience. It reveals some of the key problems encountered during these activities, in particular the lack of a planning culture among local stakeholders and the consequent tendency to respond to problems in ad hoc ways. Analysis of workshops and training courses suggests that there is a need to develop a more integrated approach to capacity building, with a strong emphasis on the way in which individual activities fit into overall planning and development processes. International development agencies could do more to encourage such an integrated approach to capacity building, planning and implementation. In doing so, they should recognise that, in the absence of a strong planning culture, informed decision making is often constrained by a lack of information. Where this is the case, it is critically important to extend the preparation stage of the project cycle to enable local stakeholders time gather the information required to develop a full understanding of problems and possibilities.
Water management and food production in China and India: a comparative assessment
Authors: Cai Ximing , Rosegrant Mark W.
Published: May 2018

China and India have different climatic and hydrologic features, which characterize their agricultural production; they have experienced different water resources development in supporting their agriculture. In this paper, we try to indicate diversified water management strategies for China and India based on comparisons between the two countries. We also address their common problems and perspectives in water management and agriculture. This paper concludes that China's major challenge is to improve irrigation by more efficient use of water. On the other hand, India may have a greater potential in irrigating more land, improving rainfed crop yields, as well as creating efficient use of water.
Fiscal perspective on irrigation water pricing: a case study of Karnataka, India
Authors: Rajaraman Indira
Published: May 2018

Pricing publicly-provided irrigation water at its scarcity value is desirable for both efficiency of usage and fiscal recovery, but paradoxically is least feasible in regions of water scarcity. This paper presents a case study of Karnataka state in India to argue that, given the rent-seeking possibilities in crop-specific water rates and the infeasibility of metering in the developing country context, a flat quantum of water entitlement per net hectare of command area, with an accompanying fixed charge per net hectare is best. Such a flat entitlement is crop-neutral and de-links quantum of use from the price, which can then be set at a (moving) compliance-maximising rate. Even if the implicit rate charged per unit of water is below scarcity value, so that irrigation remains publicly subsidised, it would not thereby be inefficiently allocated. Local user groups may be the best mechanism for enforcing the flat entitlement and could oversee any informal water trading that might develop.
Sustainable water management practices: lessons from ancient Sri Lanka
Authors: Kenyon P. , Pollett C. , Wills-Johnson N.
Published: May 2018

Many developing countries struggle with the most appropriate way by which to ensure that sufficient resources are available, in a sustainable manner, for the provision of water services. This problem is not new. Rather, it is one which most societies have faced in the past, some with considerable success. This paper considers the case of the hydraulic civilisation of ancient Sri Lanka, not from the perspective of its engineering feats, which are well-known, but from the management aspects of its irrigation system. It details how the ancient Sri Lankans devised a two-tier system which, although it had engineering and economic inefficiencies in its physical structure, was perfectly suited to the level of social capital available at the time. Given that social capital is precisely what limits many developing countries, this suggests that ancient Sri Lanka may provide lessons for water resource management which may have application in developing countries today.
Artificial mixing to reduce growth of the blue-green alga Microcystis in Lake Nieuwe Meer, Amsterdam: an evaluation of 7 years of experience
Authors: Jungo E. , Visser Petra M. , Stroom Jasper , Mur Luuc R.
Published: May 2018

The problem of Lake Nieuwe Meer (area = 1.3 km2, max. depth 30 m, Ptot = 500 mg/m3) was extensive growth of Microcystis with disturbing scum forming. Since 1993 the lake has been artificially mixed in summer by a bubble plume installation. The result is quite successful since the mass of Microcystis is up to 20 times lower than in the years before mixing and no scum is present any more. The study in Lake Nieuwe Meer showed a shift from cyanobacterial dominance (mainly Microcystis) to flagellates, green-algae and diatoms when artificial mixing was applied. Total phosphorus and nitrogen concentrations did not change as a result of mixing and had apparently no effect on the shift in the phytoplankton composition. The chlorophyll-a concentration was much lower in the mixed lake as a result of dilution. The total algae biomass decreased. The transparency did not improve. The total heat energy of the lake is slightly higher than before mixing but still remains in the range of annual fluctuation. The temperature on the surface is approximately 2°C lower. In the whole water-body oxygen was always higher than 5 mg/l. Living space for fish is therefore wider.

The installation in Lake Nieuwe Meer consists of flexible pipes near the sediment, built in a way to prevent sediment erosion and transport into the water. There are no constructions in the water-body. All mechanical parts are on land. The layout of the installation is shown in Fig. 1. Installed compressor energy is 85 kW. This is equivalent to an upper middle-class motor-car. The design was made specifically for this problem. It is based on the physical data of the algae and the plant.

It would be beneficial to use this 7 year's experience for further applications e.g. elimination of toxic algae in drinking-water reservoirs.
Application of the membrane technology to control ammonia in surface water
Authors: Koyuncu I. , Topacik D. , Turan M. , Celik M.S. , Sarikaya H.Z.
Published: May 2018

Amnonium ion is effectively removed by Reverse Osmosis membranes (Brackish water, BW; Saline water, SW). The removal efficiency of ammonium ion from a solution containing ammonium ion which is not complexed is varying in the range of 5–60%. On the contrary, ammonium ion forms complexes with other ions in water and wastewater removal efficiency was as high as 99% for the synthetic solution which contained a complex of iron and ammonium ion. Elmali reservoir which is one of the water sources of the Istanbul city is suffering from high ammonia content due to discharges of untreated wastewater. Application of the BW membrane to Elmali Reservoir water resulted in ammonia removal efficiency of about 95%. The permeate ammonia concentration of 0.2 mg/l was achieved. High removal ratio of ammonia ions in complex form is due to increased molecular diameters of the ammonium ion complexes. Increased pH values were observed in parallel to increase the ammonium ion concentrations when ammonium ion was not in complex form. Ammonium ion removal efficiency decreased with increasing pH. On the other hand, when the concentration of ammonium ion complexed with iron was increased, pH value was decreased. In parallel to the decreasing pH, an increase of removal efficiency was observed. Membrane types did not significantly affect the flux. No fouling problems were observed during the test runs and thus fluxes were practically constant throughout the experimental run. The total estimated cost of treatment will be in the range of $0.95 to $1.06/m3 for the investigated drinking water source.
A new look at filter backwash hydraulics
Authors: Akgiray Ömer , Saatçı Ahmet M.
Published: May 2018

A new approach to model media expansion during filter backwash is presented. The proposed approach is based on the assumption that the Ergun equation remains valid after fluidization. Mathematical formulas are derived for predicting expanded porosity for a given backwash velocity or backwash velocity for a given expanded porosity. These formulas can be easily used by the engineer. Values predicted using the proposed approach are in good agreement with experimental measurements.
The influence of changes in groundwater composition on the efficiency of manganese and ammonia nitrogen removal on mature quartz sand filtering beds
Authors: Bray R. , Olańczuk-Neyman K.
Published: May 2018

The results of investigations of natural groundwater treatment containing increased manganese and ammonia nitrogen concentrations are presented. The main aim of the work was to show the influence of changes in water composition on manganese and ammonia nitrogen removal from groundwater on second-stage mature quartz sand filters. According to the results obtained, the efficiency of manganese elimination from water did not depend on periodic changes in ammonia nitrogen or dissolved oxygen concentrations. However, if low oxygen concentrations (lower than 2 mg/dm3) were maintained for a longer time, the manganese concentration in the filtrate gradually increased. The ammonia nitrogen concentration in the filtered water appeared to be the most relevant factor affecting the efficient removal of manganese and the dissolved oxygen concentration was less important. The nitrification process appeared to be vulnerable to changes in the concentrations of the substrates: ammonia nitrogen (either an increase or decrease) and oxygen (an decrease). It was observed that it is necessary for nitrifying bacteria to adapt (lag phase) to rapidly changing water composition. Due to the sorption process, the inhibition of nitrification on the filtering beds did not significantly influence the efficiency of ammonia nitrogen removal.
Evaluation of the effectivity of selected filter beds for iron and manganese removal
Authors: Olańczuk-Neyman K. , Częścik P. , Łasińska E. , Bray R.
Published: May 2018

The results of experiments concerning iron and manganese removal from groundwater at a treatment facility in the first and second stage of filtration through pressure experimental filters with different filter beds are presented. Research was carried out on three parallel filters with the following filter beds: quartz sand+Hydrolit-Mn, quartz sand+pyrolusite and single medium mature quartz sand.

It was revealed that the effectiveness of iron and manganese removal from groundwater at the Sieradzka facility in Gdynia can be increased by one-stage filtering through oxidation beds of mature quartz sand or two-layered quartz sand+pyrolusite. As a result of filtration, the concentrations of both elements decreased from the average level in untreated water of 1.10 mg Fe/dm3 and 0.14 mg Mn/dm3 to below 0.2 mg Fe/dm3 and 0.05 mg Mn/dm3 in the outflow. These levels meet both the current Polish and European Union standards.
THM, haloacetic acids and other organic DBPs formation in disinfection of bromide rich Sea of Galilee (Lake Kinneret) water
Authors: Heller-Grossman L. , Manka J. , Limoni-Relis B. , Rebhun M.
Published: May 2018

Lake Kinneret (Sea of Galilee) is the main freshwater body in Israel and is the water source for the National Water Carrier (NWC). The lake water has a uniquely high bromide content 1.9 mg/L which affects DBPs (disinfection by-products) formation. Controlled experiments using different disinfectants were carried out with the lake water in order to study DBPs formation. Formation and distribution of TOX (total organic halogen) trihalomethanes (THM), haloacetic acids (HAA) and cyanogen halides were studied during the application of the following disinfectants: Chlorine, chloramine, chlorine dioxide and a combination of chlorine dioxide with chloramine. Brominated species dominated the distribution of THM, HAA and cyanogen halide. When a high dose of chlorine was applied an unusually high percent (75%) of the TOX formation potential was identified; THM constituted about 50% of the TOX formation potential and haloacetic acids 22-28%. Tribromoacetic acid was found to undergo decomposition to form bromoform. Chlorine dioxide produced insignificant concentrations of organic DBPs and chloramine produced low concentrations. Chlorine dioxide in combination with chloramine enhanced production of CNBr and THM, but their concentrations were much lower than during chlorination.
Development of coagulation theory and new coagulants for water treatment: its past, current and future trend
Authors: Jiang J.-Q.
Published: May 2018

This paper reviews the history of chemical coagulation and its effects on the water quality control and management, considers how the most favourable coagulant species and prepolymerised inorganic coagulants may be prepared by reference to the appropriate coagulant chemistry, and evaluates the overall performance of some pre-polymerised coagulants in comparison with that of conventional coagulants for water treatment.
Removal of particles using dual media filtration: modeling and experimental studies
Authors: O'Melia C.R. , Shin J.Y.
Published: May 2018

The performance of packed beds using dual media for removing particles is examined using both predictive mathematical modeling and experimental column studies. Models for the effectiveness of clean filter beds were used to simulate the effects of chemical pretreatment and filtration rate on particle removal at the onset of filtration runs. Experimental studies were conducted over complete filtration runs and were evaluated using measurements of head loss development and removals of turbidity, UV254 absorbance, and particles. The results indicate that dual media beds have significant advantages over monomedia beds during both filter ripening and filter breakthrough; they are particularly helpful at high filtration rates and during periods of inadequate chemical pretreatment. Finally, particle counts provide an earlier indicator of deteriorating filter performance than turbidity measurements at the end of a run.
Using a comprehensive model to identify the major mechanisms of chloramine decay in distribution systems
Authors: Woolschlager J. , Rittmann B. , Piriou P. , Kiene L. , Schwartz B.
Published: May 2018

The principle mechanisms of chloramine residual decay in drinking water distribution systems is examined using a comprehensive model of chloramine reactions calibrated to distribution system data. The results reveal that four principle chloramine decay mechanisms must be considered, including:

reactions with hypochlorous acid/ion (HOCl/OCl-); an auto- catalytic reaction in which chloramines spontaneously decay in the absence of other reactants; oxidation reactions with reduced forms of organics and iron; and biologically-catalyzed reactions, such as the reactions with nitrite produced by nitrifiers as well as the direct cometabolism of chloramines by nitrifiers. The chloramine reaction model fits the distribution system data best when all of these reactions, including cometabolism of chloramines by nitrifiers, are included in the model.
TiO2 assisted photocatalytic degradation of 4-chlorobenzoic acid in water: effect of type of catalyst, catalyst loading, initial contaminant concentration and solution characteristics
Authors: Dionysiou D.D. , Suidan M.T. , Baudin I. , Laîne J.M. , Huang T.L.
Published: May 2018

Photocatalytic degradation of 4chlorobenzoic acid in water was studied using different TiO2 catalysts (Degussa P-25, Ishihara ST01 and Hombikat UV-100) and solution characteristics. Mineralization of 4chlorobenzoic acid was achieved in all the experiments and total recovery of the chlorine as free Cl- was obtained. The catalyst concentration influenced the photocatalytic rates and the optimum loading concentration was determined to be different for Degussa P-25 and Ishihara ST01, mainly due to the difference in their adsorption and scattering characteristics. Comparison between the catalysts for their photocatalytic activity revealed that other factors must influence the photocatalytic reaction rates beside the surface area of the catalysts. The photocatalytic reaction rates were found to obey the Langmuir-Hinshelwood adsorptionreaction model. At pH = 7.0, the presence of Cl did not inhibit the reaction rates. At pH = 3.0, however, the photocatalytic reaction rates were higher for the solution containing NO-3 instead of Cl- at the same molar concentration.
Cement-based materials used in drinking water pipe systems
Authors: Soukatchhoff P. , Baron J. , Lessirad L.
Published: May 2018

Ductile iron pipes with cement mortar linings and concrete pipes are used with satisfaction for the transport and distribution of drinking water. The cement-based materials involved in these pipes are very well accepted, being considered as “traditional” and well proven for this application. An interaction with water however exists and two types of questions can be raised: the durability of the material over long periods (more than 50 years) and the preservation of water quality. These two aspects have been deeply investigated in the last 10 years by several European laboratories co-operating with organizations like CEN (European Standardization Committee), CEOCOR, AGHTM, etc. This paper gives an overview of the work which has been done focusing especially on a survey of the behaviour of mortars, made from different type of cements, exposed for more that 15 years to a very soft acidic water the models for calculating the calco-carbonic equilibrium and the main results of a European co-normative research programme carried out to provide information to allow the development of test methods to assess the migration of mineral and organic substances from cement-based materials in contact with drinking water.
Suspended particles in the drinking water of two distribution systems
Authors: Gauthier V. , Barbeau B. , Millette R. , Block J.-C. , Prévost M.
Published: May 2018

The concentrations of suspended particles were measured in the drinking water of two distribution systems, and the nature of these particles documented. The concentrations of particulate matter were invariably found to be small (maximum 350 μg/L). They are globally in the very low range in comparison with dissolved matter concentrations, which are measured in several hundreds of mg/L. Except during special water quality events, such as turnover of the raw water resource, results show that organic matter represents the most important fraction of suspended solids (from 40 to 76%) in treated and distributed water. Examination of the nature of the particles made it possible to develop several hypotheses about the type of particles penetrating Montreal's distribution system during the turnover period (algae skeleton, clays). These particles were found to have been transported throughout the distribution systems quite easily, and this could result in the accumulation of deposits if their surface charge were ever even slightly destabilised, or if the particles were to penetrate the laminar flow areas that are fairly typical of remote locations in distribution systems.