Arsenic(V) Removal from Drinking Water by Polyaluminum Chloride in a Sand Filter Medium

Abstract

Arsenic-containing groundwater is used normally as drinking water after treatment in rural areas of some developing countries. This study describes removing arsenate [As(V)] by contact filtration on a sand media using polyaluminum chloride (PACl) as a coagulant. Arsenic-contaminated water and PACl coagulant were introduced concurrently into a sand filter column. A PACl dose of 15 mg/L reduced the arsenic (As) concentration in a synthetic groundwater (pH=8) from 0.10 mg/L to less than 0.01 mg/L. The 81-cm deep, 16-mm diameter single-sand column treated 38.4 pore volumes before it reached an assumed maximum allowable experimental head loss (4.50 m). Reducing the PACl dose resulted in an increased As concentration in the filter effluent. The PACl precipitate-As complex could be removed from the filter by flushing. Results suggest precipitated PACl is more efficient than aluminum oxide/hydroxide solid phases in As removal. Filter performance was shown to be independent of how the PACl was distributed in the filter column.