Importance of evaluating phosphate levels in tubewells in high arsenic areas of Asia

Significant levels of naturally occurring phosphates in groundwater in some arsenic affected regions can potentially reduce removal efficiencies of some critical iron-based arsenic treatment systems that currently are among the most simple and low-cost treatment approaches. From March-December 2007, the Massachusetts Institute of Technology (MIT), the Centre for Affordable Water and Sanitation Technology (CAWST) and LEDARS, a Bangladeshi NGO, conducted pilot testing in Bangladesh of the Kanchan Arsenic Filter. Because of the varying phosphate levels in groundwater in different districts in Bangladesh, the project also included an analysis of phosphate data from arsenic studies conducted by other organizations in high arsenic areas in Vietnam, Cambodia, West Bengal and Inner Mongolia and compared them to results from Bangladesh and Nepal.The results from the analysis indicated that the ratio of iron to phosphates in the groundwater might be a good indicator for the effectiveness of iron-based arsenic removal systems in high arsenic areas.