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Van Halem, D. (author), Bakker, S.A. (author), Amy, G.L. (author), Van Dijk, J.C. (author)For more than a decade it has been known that shallow tube wells in Bangladesh are frequently contaminated with arsenic concentrations at a level that is harmful to human health. By now it is clear that a disaster of an unheard magnitude is going on: the World Health Organization has estimated that long-term exposure to arsenic in groundwater,...journal article 2009
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Van Halem, D. (author)Arsenic contamination of shallow tube well drinking water is an urgent health problem in Bangladesh. Current arsenic mitigation solutions, including (household) arsenic removal options, do not always provide a sustainable alternative for safe drinking water. A novel technology, Subsurface Arsenic Removal, relies on the existing technology of...doctoral thesis 2011
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Van Halem, D. (author)Let’s start with the United Nations Millennium Development Goals Report 2012. Remember the target? Halve, by 2015, the proportion of the population without sustainable access to safe drinking water and basic sanitation. Thanks to China and India the world has met the drinking water target in 2010, but the work is not done yet. The poorest lag...conference paper 2013
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Borges Freitas, S.C. (author), Van Halem, D. (author), Badruzzaman, A.B.M. (author), Van der Meer, W.G.J. (author)Pre-oxidation of As(III) is necessary in arsenic removal processes in order to increase its efficiency. Therefore, the Fenton Redox Chemistry is defined by catalytic activation of H2O2 and currently common used for its redox oxidative properties. In this study the effect of H2O2 production catalysed by O2 in metallic surfaces (MS), such as...conference paper 2014
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- Borges Freitas, S.C. (author), Van Halem, D. (author), Van der Meer, W.G.J. (author), Rietveld, L.C. (author) conference paper 2014
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- Wang, F. (author), van Halem, D. (author), van der Hoek, J.P. (author) journal article 2016
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Gutiérrez, Juan Pablo (author), van Halem, D. (author), Rietveld, L.C. (author)The particulate matter composition in the Upper Cauca River section was studied, considering the importance of this river for the water supply of Cali, Colombia, and the implications that the turbidity of this water source has had for the city's water treatment. Additionally, the upstream Palo River was investigated, as this river is a major...journal article 2016
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Stubbé, Stefanie M L (author), Pelgrim-Adams, Alida (author), Szántó, Gabor L. (author), van Halem, D. (author)Household Water Treatment and safe Storage (HWTS) systems aim to provide safe drinking water in an affordable manner to users where safe piped water supply is either not feasible or not reliable. In this study the effectiveness, economic parameters and costs of three selected HWTS systems were identified. The selected systems are SODIS,...journal article 2016
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Gutiérrez, Juan Pablo (author), Delgado, Luis Germán (author), van Halem, D. (author), Wessels, Peter (author), Rietveld, L.C. (author)Guaranteeing a safe and continuous drinking water supply for the city of Cali, Colombia, has become a concern for the water company of Cali, the environmental authorities, universities, and entities involved in the water resource. The progressive deterioration of the city’s water sources has led to a search for future water sources and/or...journal article 2016
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Wang, F. (author), van Halem, D. (author), Liu, G. (author), Lekkerkerker, K. (author), van der Hoek, J.P. (author)H2O2 residuals from advanced oxidation processes (AOPs) may have critical impacts on the microbial ecology and performance of subsequent biological treatment processes, but little is known. The objective of this study was to evaluate how H2O2 residuals influence sand systems with an emphasis on dissolved organic carbon (DOC) removal, microbial...journal article 2017
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van Halem, D. (author), van der Laan, H. (author), Soppe, A. I.A. (author), Heijman, Sebastiaan (author)Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal...journal article 2017
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Gude, J.C.J. (author), Rietveld, L.C. (author), van Halem, D. (author)The top layer of natural rapid sand filtration was found to effectively oxidise arsenite (As(III)) in groundwater treatment. However, the oxidation pathway has not yet been identified. The aim of this study was to investigate whether naturally formed manganese oxide (MnO<sub>2</sub>), present on filter grains, could abiotically be responsible...journal article 2017
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Gutiérrez, Juan Pablo (author), van Halem, D. (author), Rietveld, L.C. (author)The poor quality of many Colombian surface waters forces us to seek alternative, sustainable treatment solutions with the ability to manage peak pollution events and to guarantee the uninterrupted provision of safe drinking water to the population. This review assesses the potential of using riverbank filtration (RBF) for the highly turbid...journal article 2017
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Gude, J.C.J. (author), Joris, K. (author), Huysman, K. (author), Rietveld, L.C. (author), van Halem, D. (author)Current groundwater treatment facilities, mostly relying on aeration-filtration configurations, aim at the removal of iron (Fe), ammonia (NH <sub>4</sub> <sup>+</sup> ) and manganese (Mn). However, recently water companies expressed the ambition to also reduce arsenic (As) concentrations in these rapid sand filters. The aim of this study was...journal article 2018
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Gude, J.C.J. (author), Rietveld, L.C. (author), van Halem, D. (author)The objective of this study was to investigate whether arsenic-oxidising bacteria (AsOB) will grow and survive in rapid sand filters. Additionally, the interdependence of other groundwater constituents (Fe(II), Mn(II), NH<sub>4</sub>) with biological As(III) oxidation was investigated. For this purpose As(III) oxidation was monitored in pilot...journal article 2018
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Wang, F. (author), Salgado Ismodes, V.A. (author), van der Hoek, J.P. (author), van Halem, D. (author)The removal of bromate (BrO<sub>3</sub> <sup>-</sup>) as a byproduct of ozonation in subsequent managed aquifer recharge (MAR) systems has so far gained little attention. This preliminary study with anoxic batch experiments was executed to explore the feasibility of chemical BrO<sub>3</sub> <sup>-</sup> reduction in Fe-reducing zones of MAR...journal article 2018
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de Ridder, D.J. (author), van de Wetering, T. S.C.M. (author), van Dijk, T. (author), van Halem, D. (author)Our aim was to systematically investigate the influence of anions (HPO<sub>4</sub> <sup>2−</sup>), cations (Ca<sup>2+</sup>, Mg<sup>2+</sup>) and neutral H<sub>4</sub>SiO<sub>4</sub> on Fe flocculation and As(III) removal in the complex natural water matrix. For this purpose, three different anaerobic groundwaters were selected and...journal article 2018
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de Ridder, D.J. (author), van Halem, D. (author)In this study, the importance of charge interactions during flocculation of Fe<sup>3+</sup> in the presence of particles and anions/cations at various pH values was investigated. SiO<sub>2, (s)</sub> and ZnO<sub>(s)</sub> were dosed as particles to promote charge interactions and/or serve as a nucleus to accelerate floc formation. In the pH...journal article 2018
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Gutiérrez, Juan Pablo (author), van Halem, D. (author), Uijttewaal, W.S.J. (author), del Risco, Efraín (author), Rietveld, L.C. (author)As a consequence of the suspended sediments in river water, cake formation on the streambed and clogging of the aquifer may occur, leading to a decline in the production yield of riverbank filtration systems, particularly in highly turbid river waters. However, naturally occurring flow forces may induce sufficient scouring of the streambed,...journal article 2018
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Gude, J.C.J. (author), Rietveld, L.C. (author), van Halem, D. (author)In the top layer of aerated rapid sand filtration systems, uncharged As(III) is biologically converted to charged As(V). Subsequently, the main removal mechanism for As(V) is adsorption onto oxidised, flocculated Fe(III) (hydrous ferric hydroxides; HFO). The aim of this research was to understand the interactions between As and Fe in...journal article 2018