ENVR 12 |
| Michael Berg, Samuel Luzi, Trang T. K. Pham, Viet H. Pham, Walter Giger, and Doris Stüben. |
| A study investigating arsenic removal efficiencies of household sand filters and passive co-precipitation in rural areas of Vietnam will be presented. The groundwater in this region is polluted by arsenic (1–3000 µg/L) and contains high iron concentrations due to highly reducing conditions. From the groundwaters containing 10-385 µg/L As, 0.1-47 mg/L Fe and 0.01-3.7 mg/L P, identical average removal rates of 81% (20–99%) were found for both, sand filters and passive co-precipitation experiments. Residual arsenic levels below 10 µg/L were reached by 40% of the sand filters and 90% were below 50 µg/L. High iron concentrations clearly enhanced arsenic removal while phosphate levels above 2.5 mg P/L resulted in slightly lower removal. To reach arsenic concentrations below 50 or 10 µg/L, Fe/As ratios in raw groundwater of 50 or 250, respectively, were required. Interestingly, the arsenic removal efficiencies were higher than expected from laboratory experiments. This could be demonstrated by computing the field data with a mathematical model based on sorption constants determined from passive co-precipitation experiments in artificial groundwater. |
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Occurrence, Chemistry, Toxicity and Remediation of Arsenic
8:00 AM-11:00 AM, Sunday, 26 March 2006 Georgia World Congress Center -- B218, Oral
Division of Environmental Chemistry |