Towards achieving <1 ug/L at Katwijk, Ouddorp and Leiduin. Baseline study and batch experiments with KMnO4 and FeCI3 to remove arsenic

Arsenic (As) is a toxic element which occurs naturally in the earth’s crust. It has been reported to cause contamination of drinking water sources in many parts of the world. World Health Organization (WHO) guideline for As in drinking water is 10 µg/L. The drinking water companies in the Netherlands are committed to produce drinking water with impeccable quality and therefore have voluntarily accepted 1 µg/L as the new target for As in drinking water.
This study has been carried out in the joint research program of Dutch dune water companies (DPWE). Three drinking water treatment plants (DWTPs), namely Katwijk (Dunea), Ouddorp (Evides) and Leiduin (Waternet) were included in this study with the aim of investigating the existing As removal efficiency of the existing treatment setups and to pin- point the treatment processes that are responsible for the observed As removal capacity. Furthermore, at each of the locations, the possibility of achieving <1 µg/L of As in the produced drinking water is studied. The technique used is coprecipitation of As with naturally available or artificially added iron (Fe), with or without pretreatment of the water with potassium permanganate (KMnO4). In order to establish the baseline knowledge regarding As removal the available water quality data from the routine monitoring programs of the DWTPs was analysed. Fresh sampling campaigns were carried out at the full-scale treatment plants whenever required. Jar tests were carried out to investigate the influence of KMnO4 and Fe dosing on As removal, using actual streams of interest from the DWTPs. De Nederlandse waterbedrijven hebben zichzelf tot doel gesteld de arseenconcentraties in drinkwater te verlagen tot onder 1 μg/L. Voor drie DPWE bedrijven is op drie verschillende locaties gemeten wat de huidige arseenconcentraties van het ruw- en reinwater zijn. Verder is met behulp van laboratoriumtesten onderzocht hoe deze concentraties in het reinwater kunnen worden verlaagd. Toevoeging van ijzer(III), eventueel in combinatie met kaliumpermangaat als oxidator, aan het influent van snelle zandfilters lijkt een effectieve methode te kunnen zijn hiervoor, die relatief eenvoudig kan worden geïmplementeerd.