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Nieuwegein, Netherlands

A method, the comparison of flow pattern distributions (CFPD), is described in which the specific representation of flow measurements for two different time periods allows a direct, quantitative interpretation of changes in the pattern. Two types of changes can be distinguished. The first is changes from one period to the next in demand consistent with the existing pattern, e.g. due to changing weather or changes in the population size. The second type is inconsistent changes which may be due to increased leakage. The method is successfully applied to drinking water distribution systems of different sizes and characteristics. Being data driven, it is independent of model assumptions and therefore insensitive to uncertainties therein which may hinder some other leakage determination methods. Because it is simple to implement and apply but nevertheless powerful in distinguishing between consistent and inconsistent changes in water demand, the method provides water companies with a way to constantly monitor their networks for possible changes in customer demand and the possible occurrence of new leakages and also check archived data for similar changes. This could render additional information about customer behavior and the evolving condition of the network from data which is usually readily available at water companies. © IWA Publishing 2013.


Bichai F.,Harvard University | Smeets P.W.M.H.,KWR Watercycle Research Institute
Water Research | Year: 2013

Innovation in the water sector is at play when addressing the global water security challenge. This paper highlights an emerging role for Quantitative Microbial Risk Assessment (QMRA) and health-based targets in the design and application of robust and flexible water quality regulation to protect public health. This role is especially critical as traditional supply sources are subject to increased contamination, and recycled wastewater and stormwater become a crucial contribution to integrated water supply strategies. Benefits and weaknesses of QMRA-based regulation are likely to be perceived differently by the multiple stakeholders involved. The goal of the current study is to evaluate the experience of QMRA-based regulation implementation in the Netherlands and Australia, and to draw some lessons learned for regulators, policy makers, the industry and scientists. Water experts from regulatory bodies, government, water utilities, and scientists were interviewed in both countries. This paper explores how QMRA-based regulation has helped decision-making in the Netherlands in drinking water safety management over the past decade. Implementation is more recent in Australia: an analysis of current institutional barriers to nationally harmonized implementation for water recycling regulation is presented. This in-depth retrospective analysis of experiences and perceptions highlights the benefits of QMRA-based regulation and the challenges of implementation. QMRA provides a better assessment of water safety than the absence of indicators. Setting a health target addresses the balance between investments and public safety, and helps understand risks from alternative water sources. Challenges lie in efficient monitoring, institutional support for utilities, interpretation of uncertainty by regulators, and risk communication to consumers. © 2013 Elsevier Ltd.


Oosterhuis M.,Water Board Regge en Dinkel | Sacher F.,DVGW Technologiezentrum Wasser | ter Laak T.L.,KWR Watercycle Research Institute
Science of the Total Environment | Year: 2013

Local consumption data of pharmaceuticals were used to study the emission to wastewater and surface waters in two small Dutch water catchments. For nine high consumption pharmaceuticals: metformin, metoprolol, sotalol, losartan, valsartan, irbesartan, hydrochlorothiazide, diclofenac and carbamazepine, predicted emissions were compared to wastewater concentrations, removal in sewage treatment plants and recovery in regional surface water. The study shows that local consumption data can be very useful to select pharmaceuticals for monitoring and to predict wastewater concentrations. Measured influent concentrations were on average 78% with a range of 31-138% of predicted influent concentrations. Metformin is the pharmaceutical with the highest concentration in wastewater (64-98. μg/L) but it is removed with > 98% in sewage treatment plants (STP). Guanylurea, a biodegradation product of metformin, was detected in STP effluents and surface waters at concentrations of 39-56. μg/L and 1.8-3.9. μg/L, respectively. The STP removal of the different pharmaceuticals varied strongly. For carbamazepine, hydrochlorothiazide and sotalol a significant better removal was found at higher temperatures and longer hydraulic retention times while for metoprolol significantly better removal was only observed at higher temperatures. Predicting environmental concentrations from regional consumption data might be an alternative to monitoring of pharmaceuticals in wastewater and surface waters. © 2012 .


Wullings B.A.,KWR Watercycle Research Institute | Bakker G.,Vitens Water Technology | Van Der Kooij D.,KWR Watercycle Research Institute
Applied and Environmental Microbiology | Year: 2011

Two unchlorinated drinking water supplies were investigated to assess the potential of water treatment and distribution systems to support the growth of Legionella spp. The treatment plant for supply A distributed treated groundwater with a low concentration (<0.5 ppm of C) of natural organic matter (NOM), and the treatment plant for supply B distributed treated groundwater with a high NOM concentration (8 ppm of C). In both supplies, the water temperature ranged from about 10°C after treatment to 18°C during distribution. The concentrations of Legionella spp. in distributed water, analyzed with quantitative PCR (Q-PCR), averaged 2.9 (± 1.9) × 102 cells liter-1 in supply A and 2.5 (± 1.6) × 10 3 cells liter-1 in supply B. No Legionella was observed with the culture method. A total of 346 clones (96 operational taxonomical units [OTUs] with ≥97% sequence similarity) were retrieved from water and biofilms of supply A and 251 (43 OTUs) from supply B. The estimation of the average value of total species richness (Chao1) in supply A (153) was clearly higher than that for supply B (58). In each supply, about 77% of the sequences showed <97% similarity to described species. Sequences related to L. pneumophila were only incidentally observed. The Legionella populations of the two supplies are divided into two distinct clusters based on distances in the phylogenetic tree as fractions of the branch length. Thus, a large variety of mostly yet-undescribed Legionella spp. proliferates in unchlorinated water supplies at temperatures below 18°C. The lowest concentration and greatest diversity were observed in the supply with the low NOM concentration. Copyright © 2011, American Society for Microbiology.


Wols B.A.,KWR Watercycle Research Institute | Wols B.A.,Technical University of Delft | Hofman-Caris C.H.M.,KWR Watercycle Research Institute
Water Research | Year: 2012

Emerging organic contaminants (pharmaceutical compounds, personal care products, pesticides, hormones, surfactants, fire retardants, fuel additives etc.) are increasingly found in water sources and therefore need to be controlled by water treatment technology. UV advanced oxidation technologies are often used as an effective barrier against organic contaminants. The combined operation of direct photolysis and reaction with hydroxyl radicals ensures good results for a wide range of contaminants. In this review, an overview is provided of the photochemical reaction parameters (quantum yield, molar absorption, OH radical reaction rate constant) of more than 100 organic micropollutants. These parameters allow for a prediction of organic contaminant removal by UV advanced oxidation systems. An example of contaminant degradation is elaborated for a simplified UV/H 2O 2 system. © 2012 Elsevier Ltd.

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