Retrofitting arsenic-iron removal plants in rural Bangladesh for performance enhancement

As a result of naturally occurring arsenic in groundwater, it is estimated that 42-60 million people in Bangladesh are exposed to arsenic at concentrations greater than the World Health Organization (WHO) guideline of 10 g/L. Arsenic-Iron Removal Plants (AIRPs) are capable of removing 50-90% of arsenic from groundwater, but are frequently unable to meet the WHO guideline. The effectiveness of three design modifications intended to improve the performance of AIRPs is described: (1) the addition of scrap or locally available iron to the filtration media, (2) raising the intake pipe that connects the two tanks of the AIRP, and (3) introducing baffles to the aeration tank. Total arsenic, iron, phosphate, and dissolved oxygen were measured to determine the impact of each modification. The addition of iron media showed an increase in arsenic removal up to 13%, while raising the pipe intake accounted for a 3% increase in arsenic removal. The installation of both modifications to the same AIRP is expected to reduce the lifetime body burden from drinking water by one-half. The addition of baffles to the aeration tank showed no evidence of improving the arsenic removal capabilities of the AIRP.