Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
Water Res. 2011 Apr;45(8):2496-506. doi: 10.1016/j.watres.2011.02.005. Epub 2011 Feb 12.
Groundwater contamination by gasoline spill is a worldwide environmental problem. Gasoline contains methyl tertiary-butyl ether (MTBE) (a fuel oxygenates) and benzene, which are the chemicals of concerns among the gasoline components. In this study, an in situ chemical oxidation (ISCO) barrier system was developed to evaluate the feasibility of applying this passive system on the control of MTBE and benzene plume in aquifer. The developed ISCO barrier contained oxidant-releasing materials, which could release oxidants (e.g., persulfate) when contact with water for the contaminants' oxidation in groundwater. In this study, laboratory-scale fill-and-draw experiments were conducted to determine the component ratios of the oxidant-releasing materials and evaluate the persulfate release rates. Results indicate that the average persulfate-releasing rate of 7.26 mg S(2)O(8)(2-)/d/g was obtained when the mass ratio of sodium persulfate/cement/sand/water was 1/1.4/0.24/0.7. The column study was conducted to evaluate the efficiency of in situ application of the developed ISCO barrier system on MTBE and benzene oxidation. Results from the column study indicate that approximately 86-92% of MTBE and 95-99% of benzene could be removed during the early persulfate-releasing stage (before 48 pore volumes of groundwater pumping). The removal efficiencies for MTBE and benzene dropped to approximately 40-56% and 85-93%, respectively, during the latter part of the releasing period due to the decreased persulfate-releasing rate. Results reveal that acetone, byproduct of MTBE, was observed and then further oxidized completely. Results suggest that the addition of ferrous ion would activate the persulfate oxidation. However, excess ferrous ion would compete with organic contaminants for persulfate, and thus, cause the decrease in contaminant oxidation rates. The proposed treatment scheme would be expected to provide a more cost-effective alternative to remediate MTBE, benzene, and other petroleum-hydrocarbon contaminated aquifers. Results from this study will be useful in designing a scale-up system for field application.
地下水受汽油渗漏污染是一个全球性的环境问题。汽油中含有甲基叔丁基醚（MTBE）（一种燃料含氧化合物）和苯，这些都是汽油成分中需要关注的化学物质。在本研究中，开发了一种原位化学氧化（ISCO）阻隔系统，以评估该被动系统控制含水层中 MTBE 和苯羽流的可行性。所开发的 ISCO 阻隔系统包含释放氧化剂的材料，当与水接触时，这些材料可释放氧化剂（例如过硫酸盐），以氧化地下水中的污染物。在本研究中，进行了实验室规模的填充-抽取实验，以确定氧化剂释放材料的成分比例，并评估过硫酸盐的释放速率。结果表明，当过硫酸钠/水泥/砂/水的质量比为 1/1.4/0.24/0.7 时，过硫酸盐的平均释放速率为 7.26mg S(2)O(8)(2-)/d/g。进行了柱实验以评估开发的 ISCO 阻隔系统原位应用于 MTBE 和苯氧化的效率。柱实验的结果表明，在早期过硫酸盐释放阶段（地下水抽取前 48 个孔隙体积），约有 86-92%的 MTBE 和 95-99%的苯可以被去除。在释放期的后半段，由于过硫酸盐释放速率的降低，MTBE 和苯的去除效率分别降至约 40-56%和 85-93%。结果表明，观察到 MTBE 的副产物丙酮，然后进一步完全氧化。结果表明，亚铁离子的添加会激活过硫酸盐的氧化。然而，过量的亚铁离子会与有机污染物竞争过硫酸盐，从而导致污染物氧化速率降低。预期所提出的处理方案将为修复 MTBE、苯和其他石油烃污染的含水层提供更具成本效益的替代方案。本研究的结果将有助于设计现场应用的规模化系统。
