Bangladesh and neighboring areas face large health threats from drinking arseniccontaminatedground water. Arsenic levels in Bangladesh ground water are typically severalhundred μg/L (compared to WHO recommendation of 10 μg/L for the MCL). About 50 millionpeople drink such water, with hundreds of thousands already showing serious adverse healtheffects in what is described as the largest mass poisoning in history. The challenge is todevelop a method for arsenic remediation that is (1) technically effective for removing arsenicdown to 10 μg/L in the presence of other competing ions in the water, (2) affordable to most ofthe local population, (3) robust and easy to operate and maintain, and (4) does not require useof other toxic or hazardous chemicals. We describe a novel method that aims to meet thesegoals. Electrochemical Arsenic Removal (ECAR) uses a small DC current and ordinary steelelectrodes to produce a specific type of iron rust in the arsenic-contaminated ground water thatbinds to the arsenic and can be removed by filtration. We describe results using syntheticgroundwater prepared in the laboratory, and also preliminary results from real Bangladeshgroundwaters. We describe the design of a small ECAR reactor to treat 100 L of water at time,for a technical trial in West Bengal (India). Lastly, we show results from Extended X-rayAbsorption Fine Structure (EXAFS) analysis that suggests the structure of the iron precipitateand the dominant mode of arsenic surface complexation.
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