Arsenic removal from groundwater by household sand filters:: Comparative field study, model calculations, and health benefits
Arsenic removal from groundwater by household sand filters:: Comparative field study, model calculations, and health benefits
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DOI：
10.1021/es060144z
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发表时间：
2006-09-01
影响因子：
11.4
通讯作者：
Stueben, Doris
中科院分区：
文献类型：
--
作者：
Berg, Michael;Luzi, Samuel;Stueben, Doris
在越南红河三角洲的农村地区研究了43个家用砂滤器的除砷效率。同时，从同一住户和另外31个管井中采集了原水，以研究砷与溶液中的水合三价铁共沉淀，即，而不接触沙表面。砂滤法和共沉淀法对含As 10-382 μ g/L、Fe <0.1-48 mg/L、P < 0.01-3.7 mg/L和Mn 0.05-3.3 mg/L的地下水的平均去除率相近，分别为80%和76%。过滤过程只需要几分钟。铁、磷酸盐和锰的去除率分别> 99%、90%和71%。地下水中溶解铁的浓度是砷去除的决定性因素。90%的砂滤器的残留砷水平低于50 Ag/L，40%甚至低于10 Ag/L。要求Fe/As比>= 50或>= 250，以确保砷去除水平分别低于50或10 Ag/L。磷酸盐浓度> 2.5 mg P/L略微阻碍了砂滤和共沉淀效率。有趣的是，总的砷消除高于预测模型计算的基础上确定的吸附常数与人工地下水共沉淀实验。这一观察假设是由于涉及锰，微生物，并可能溶解在天然地下水中的有机物的As（III）氧化。从头发分析中可以清楚地看出，饮用砂滤水的人砷负荷降低。经调查，砂过滤器在广泛的地下水成分中运行速度快，效果好，因此也是其他受砷影响地区的一种可行的缓解方案。对孟加拉国进行的一项估计表明，在84%的受污染地下水中，砷的中位残留水平可达到25微克/升。从泵送的水中很容易观察到铁的去除，使得砂滤器的效果即使对不知道砷问题的人也能立即识别。
Arsenic removal efficiencies of 43 household sand filters were studied in rural areas of the Red River Delta in Vietnam. Simultaneously, raw groundwater from the same households and additional 31 tubewells was sampled to investigate arsenic coprecipitation with hydrous ferric iron from solution, i.e., without contact to sand surfaces. From the groundwaters containing 10-382 mu g/L As, < 0.1-48 mg/L Fe, < 0.01-3.7 mg/L P, and 0.05-3.3 mg/L Mn, similar average removal rates of 80% and 76% were found for the sand filter and coprecipitation experiments, respectively. The filtering process requires only a few minutes. Removal efficiencies of Fe, phosphate, and Mn were > 99%, 90%, and 71%, respectively. The concentration of dissolved iron in groundwater was the decisive factor for the removal of arsenic. Residual arsenic levels below 50 Ag/L were achieved by 90% of the studied sand filters, and 40% were even below 10 Ag/L. Fe/As ratios of >= 50 or >= 250 were required to ensure arsenic removal to levels below 50 or 10 Ag/L, respectively. Phosphate concentrations > 2.5 mg P/L slightly hampered the sand filter and coprecipitation efficiencies. Interestingly, the overall arsenic elimination was higher than predicted from model calculations based on sorption constants determined from coprecipitation experiments with artificial groundwater. This observation is assumed to result from As(III) oxidation involving Mn, microorganisms, and possibly dissolved organic matter present in the natural groundwaters. Clear evidence of lowered arsenic burden for people consuming sand-filtered water is demonstrated from hair analyses. The investigated sand filters proved to operate fast and robust for a broad range of groundwater composition and are thus also a viable option for mitigation in other arsenic affected regions. An estimation conducted for Bangladesh indicates that a median residual level of 25 Ag/L arsenic could be reached in 84% of the polluted groundwater. The easily observable removal of iron from the pumped water makes the effect of a sand filter immediately recognizable even to people who are not aware of the arsenic problem.