A novel technology to remove arsenic from drinking water for Bangladesh tubewells

Bangladesh and neighboring areas face large health threats from drinking arseniccontaminated ground water. Arsenic levels in Bangladesh ground water are typically several hundred μg/L (compared to WHO recommendation of 10 μg/L for the MCL). About 50 million people drink such water, with hundreds of thousands already showing serious adverse health effects in what is described as the largest mass poisoning in history. The challenge is to develop a method for arsenic remediation that is (1) technically effective for removing arsenic down to 10 μg/L in the presence of other competing ions in the water, (2) affordable to most of the local population, (3) robust and easy to operate and maintain, and (4) does not require use of other toxic or hazardous chemicals. We describe a novel method that aims to meet these goals. ElectroChemical Arsenic Removal (ECAR) uses a small DC current and ordinary steel electrodes to produce a specific type of iron rust in the arsenic-contaminated ground water that binds to the arsenic and can be removed by filtration. We describe results using synthetic groundwater prepared in the laboratory, and also preliminary results from real Bangladesh groundwaters. 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-ray Absorption Fine Structure (EXAFS) analysis that suggests the structure of the iron precipitate and the dominant mode of arsenic surface complexation.