Arsenic removal by Advanced Oxidation - Coprecipitation - Filtration (AOCF)

Arsenic (As) contamination of drinking water is a global issue, affecting health of millions of people in many countries. Drinking water companies in the Netherlands have recently established 1 µg/L as the guideline for As in drinking water based on dose-effect modelling of low-level As in Dutch drinking water which has shown that 10 µg/L is not sufficiently protective for the health of Dutch population. In the Netherlands some of the water treatment plants (WTPs) produce drinking water with higher than 1 µg/L As and currently Dutch drinking water companies are investigating options to reduce As to <1 µg/L at these WTPs. Arsenic removal by Advanced Oxidation – Coprecipitation – Filtration (AOCF) is a promising As removal method. It involves dosing a strong oxidant (e.g. NaMnO4) and an iron (Fe) based coagulant (e.g. FeCl3) in water to remove As from water. The permanganate (MnO4) rapidly oxidizes As(III) to As(V) and FeCl3 produces Fe(III)(oxyhydr)oxides in water that adsorb As(V) from water. The As bearing Fe(III)(oxyhydr)oxides are removed typically in a rapid sand filter. The overall objective of this study was to investigate As reduction to <1 µg/L by Advanced Oxidation – Coprecipitation – Filtration (AOCF) under different ion compositions and filtration conditions, as well as to gain mechanistic understanding of the process to determine the key guiding principles for full scale implementation.