Searched for: author:"van Halem, D."
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Wei, L. (author), Zietzschmann, F.E. (author), Rietveld, L.C. (author), van Halem, D. (author)
Millions of people worldwide are exposed to excessive concentrations of fluoride (F<sup>−</sup>) from groundwater sources. Ca-Al-CO<sub>3</sub> layered double hydroxides (LDHs) have shown promising defluoridation efficiency; however, defluoridation by Ca-Al-CO<sub>3</sub> LDHs is highly pH sensitive. This study showed that simultaneous...
journal article 2021
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Roy, M. (author), van Genuchten, Case M. (author), Rietveld, L.C. (author), van Halem, D. (author)
Arsenic (As) is a toxic element present in many (ground)water sources in the world. Most conventional As removal techniques require pre-oxidation of the neutral arsenite (As(III)) species to the negatively charged arsenate (As(V)) oxyanion to optimize As removal and minimize chemical use. In this work, a novel, continuous-flow As removal...
journal article 2021
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Bicudo, Bruno (author), van Halem, D. (author), Trikannad, S.A. (author), Ferrero, Giuliana (author), Medema, G.J. (author)
In this paper we analyse the feasibility of low voltage iron electrocoagulation as a means of municipal secondary effluent treatment with a focus on removal of microbial indicators, Antibiotic Resistant Bacteria (ARB) and nutrients. A laboratory scale batch unit equipped with iron electrodes was used on synthetic and real secondary effluent...
journal article 2021
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Wei, L. (author), Zietzschmann, F.E. (author), Rietveld, L.C. (author), van Halem, D. (author)
In this study, F<sup>−</sup> removal by Ca–Al–CO<sub>3</sub> layered double hydroxides (LDHs) was investigated at environmentally-relevant concentration ranges (2–12 mg/L) to below the WHO guideline, with an emphasis on the effect of LDHs’ modification, as well as the effects of initial F<sup>−</sup> concentration, adsorbent dose, pH,...
journal article 2020
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Mona Youssef Maowad, M. (author), van Halem, D. (author), Medema, G.J. (author)
Ceramic pot filters are household water treatment and safe storage (HWTS) systems designed to improve the microbial quality of drinking water. They yield high log reduction values (LRVs) for bacterial and protozoan pathogens but provide very little removal of viruses. This study investigated virus removal of ceramic filter discs (CFDs), using...
journal article 2020
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Gonzalez Rodriquez, B.J. (author), Heijman, Sebastiaan (author), Rietveld, L.C. (author), van Halem, D. (author)
In Nicaragua, a Central American country, geothermally influenced waters are frequently found to be contaminated with arsenic (as As(V)). This study investigated the effect of high-temperatures (25–50 °C), as found in geothermally influenced source waters, on the rejection of monovalent H2AsO4 - and divalent HAsO4 2- species (at pH 6,7 and 8)...
journal article 2019
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Gonzalez Rodriquez, B.J. (author), Heijman, Sebastiaan (author), Rietveld, L.C. (author), van Halem, D. (author)
This research evaluated the effect of different fluxes (16, 23 &amp; 30 L/m <sup>2</sup> h) and temperatures (31,35 &amp; 43 °C) on the rejection of As(V) during nanofiltration (NF) of natural geothermal influenced groundwater in Nicaragua. A NF pilot plant powered by solar panels was built and operated in rural community Telica, exposed to...
journal article 2019
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Gonzalez Rodriquez, B.J. (author), Rietveld, L.C. (author), Longley, A. J. (author), van Halem, D. (author)
Several surveys have been conducted in Nicaragua between 1996 and 2015 confirming the presence of high levels of arsenic (&gt;10 μg/L). In this paper, these peer-reviewed (n = 2) and non-peer reviewed sources (n = 14) have been combined to provide an extensive overview of the arsenic contamination of drinking water sources in Nicaragua. So...
review 2019
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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
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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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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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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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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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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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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), 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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Wang, F. (author), van Halem, D. (author), Liu, G. (author), Lekkerkerker-Teunissen, 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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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
Searched for: author:"van Halem, D."
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