ABSTRACT
For drinking water production, the influence of cation exchange and pellet softening on subsequent arsenic (As) removal by iron was investigated. It was found that Ca2+(aq) removal had limited effect on iron floc growth, but the presence of fine carry-over hindered floc growth severely. Compared to a situation without softening, implementing cation exchange resulted in an increase of 25% in the required iron dose for As removal, while it had to be doubled after pellet softening. Jar test do, however, underestimate As adsorption when compared to pilot filters, since they only simulate reactions in the filter supernatant.
