Arsenic removal from drinking water using iron oxide-coated sand

This article describes experiments in which iron oxide-coated sand (IOCS) was used to study the removal of both As(V) and As(III) to a level less than 5 mug L-1 in drinking water. Iron oxide-coated sand 2 (IOCS-2) prepared through high temperature coating process was used in batch and column studies to assess the effectiveness and suitability. The isotherm study results showed that the observed data fitted well with the Langmuir model, and the adsorption maximum for IOCS-2 at pH 7.6 was estimated to be 42.6 and 4 1.1 mug As g(-1) IOCS-2 for As(V) and As(III), respectively. In the fixed bed column tests to study arsenic removal from the tap water, good performance of IOCS-2 was observed in respect of bed volumes achieved and arsenic removal capacity. Five cycles of column tests were conducted to evaluate the performance of IOCS-2, and arsenic was successfully recovered from the media through regeneration and backwash operations. High bed volumes (860 to 1403) up to a breakthrough concentration of 5 mug L-1 were achieved in the column studies with tap water, and the bed volumes achieved in the studies with natural water (containing arsenic) were 1520. The results of both the batch and column studies showed that iron oxide-coated sand filtration could be effectively used to achieve less than 5 mug L-1 As in drinking water.