GSA Annual Meeting in Indianapolis, Indiana, USA - 2018

Paper No. 281-5
Presentation Time: 2:40 PM

ARSENITE REMOVAL IN GROUNDWATER TREATMENT PLANTS BY SEQUENTIAL PERMANGANATE―FERRIC TREATMENT


AHMAD, Arslan, Drinking Water Treatment, KWR Watercycle Research Institute, Groningenhaven 7, P.O. Box 1072, Nieuwegein, 3430 BB, Netherlands; KTH-International Groundwater Arsenic Research Group, Department of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology, Teknikringen 10B, Stockholm, SE-100 44, Sweden; Department of Environmental Technology, Wageningen University and Research (WUR), Wageningen, 6708 PB, Netherlands, CORNELISSEN, Emile, Drinking Water Treatment, KWR Watercycle Research Institute, Groningenhaven 7, P.O. Box 1072, Nieuwegein, 3430 BB, Netherlands, WAL, Albert van der, Department of Environmental Technology, Wageningen University and Research (WUR), Wageningen, 6708 PB, Netherlands and BHATTACHARYA, Prosun, KTH-International Groundwater Arsenic Research Group, Dept of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology, Teknikringen 10B, Stockholm, SE-10044, Sweden

The Dutch drinking water sector is actively investigating methods to reduce arsenic (As) to <1 µg/L in drinking water supply. We investigated (1) the effectiveness of sequential permanganate (MnO4)—ferric (Fe(III)) dosing during aeration—rapid sand filtration to achieve <1 µg/L As (2) the influence of MnO4—Fe(III) dosing on pre-established removal patterns of As(III), Fe(II), Mn(II) and NH4+ in rapid sand filters and (3) the influence of MnO4—Fe(III) dosing on the settling and molecular-scale structural properties of the filter backwash solids. We report that MnO4—Fe(III) dosing is an effective technique to improve arsenite [As(III)] removal at groundwater treatment plants. At a typical aeration—rapid sand filtration facility in the Netherlands effluent As concentrations of <1 µg/L were achieved with 1.2 mg/L MnO4 and 1.8 mg/L Fe(III). The optimized combination of MnO4 and Fe(III) doses did not affect the removal efficiency of Fe(II), Mn(II) and NH4+ in rapid sand filters, however, the removal patterns of Fe(II) and Mn(II) in rapid sand filter were altered, as well as the settling behaviour of backwash solids. The characterization of backwash solids by Fe K-edge X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) showed that the altered settling behaviour of backwash solids was not due to changes in the molecular-scale structure of Fe-precipitates that formed during treatment.

Key words

Arsenic removal; Arsenite oxidation; Drinking water; Groundwater treatment; Permanganate; Rapid sand filtration