Modified Biosand Filter for Provisioning of Potable Water to Rural Households Affected by Chronic Arsenic Pollution in Groundwater

Abstract

Chronic arsenic (As) pollution in aquifers is one of the major challenges faced by economically and socially marginalized sections of the world, which often depend heavily on groundwater for their sustenance. To safeguard these sections against As poisoning, an easy-to-use and sustainable water-treatment solution is warranted. This study was undertaken to systematically evaluate the performance and feasibility of a low-cost modified biosand filter (JalKalp) in providing potable water to affected rural households in India. JalKalp removes As by sorption on rusted-iron nails and pathogens by an additional copper layer. Initially, As-removal efficiencies of this filter were evaluated under laboratory conditions using (1) unpolluted groundwater spiked with variable concentrations (50–500 μg/L) of total dissolved arsenic (As_T), either as As(V), or As(III), or both; and (2) real As-polluted groundwater (∼150 μg/L). Results indicated that the JalKalp filter removed As_T with an efficiency of 95–99% and passed all water quality tests, except hardness and alkalinity. An ∼3-year long “JalKalp” program was then initiated to provide clean drinking water in selected villages of Bihar, India with the support of local agents, nongovernmental and governmental organizations. Filters were installed in select households (n = 22), and the community was involved in the program through training and workshops. The performance of these filters was evaluated through the testing of water and sludge generated, and the conduct of socioeconomic and health surveys. The filter was equally effective under field conditions and removed As_T (<10 μg/L), total iron (<1 mg/L), and fecal coliforms at all locations, at a cost of ∼INR 0.28 (US$ ∼0.004)/L of treated water. JalKalp requires replacement of iron nails after an estimated ∼1.7 years of treatment of ∼6,000 L of water containing 100 μg/L of As_T. Toxicity characteristic leaching procedure on As-containing sludge after filtration indicated that the sludge was not hazardous and could be disposed safely in landfills along with regular municipal waste. Findings from this study could be replicated elsewhere in providing immediate solutions to As-affected water pollution by enabling independent construction and sustainable use of this potentially long-lasting filter.