Department of Civil and Environmental Engineering, University of Maryland, College Park, MD, USA.
US Department of Agriculture, Agricultural Research Service, Beltsville, MD, USA.
Environ Sci Pollut Res Int. 2018 Mar;25(9):8735-8746. doi: 10.1007/s11356-017-1137-1. Epub 2018 Jan 11.
Trichloroethylene (TCE) is a highly effective industrial degreasing agent and known carcinogen. It was frequently buried improperly in landfills and has subsequently become one of the most common groundwater and soil contaminants in the USA. A common strategy to remediate TCE-contaminated sites and to prevent movement of the TCE plumes into waterways is to construct biowalls which consist of biomaterials and amendments to enhance biodegradation. This approach was chosen to contain a TCE plume emanating from a closed landfill in Maryland. However, predicting the effectiveness of biowalls is often site specific. Therefore, we conducted an extensive series of batch reactor studies at 12 °C as opposed to the typical room temperature to examine biowall fill-material combinations including the effects of zero-valent iron (ZVI) and glycerol amendments. No detectable TCE was observed after several months in the laboratory study when using the unamended 4:3 mulch-to-compost combination. In the constructed biowall, this mixture reduced the upstream TCE concentration by approximately 90% and generated ethylene downstream, an indication of successful reductive dechlorination. However, the more toxic degradation product vinyl chloride (VC) was also detected downstream at levels approximately ten times greater than the maximum contaminant level. This indicates that incomplete degradation also occurred. In the laboratory, ZVI reduced VC formation. A hazard quotient was calculated for the landfill site with and without the biowall. The addition of the biowall decreased the hazard quotient by 88%.
三氯乙烯（TCE）是一种高效的工业脱脂剂和已知的致癌物质。它经常被不当埋在垃圾填埋场中，因此成为美国最常见的地下水和土壤污染物之一。修复 TCE 污染场地并防止 TCE 羽流进入水道的一种常见策略是建造生物墙，生物墙由生物材料和改良剂组成，以增强生物降解。选择这种方法是为了控制马里兰州一个封闭垃圾填埋场散发的 TCE 羽流。然而，生物墙的有效性通常因地点而异。因此，我们在 12°C 进行了一系列广泛的批式反应器研究，而不是典型的室温，以研究生物墙填充材料组合，包括零价铁 (ZVI) 和甘油改良剂的影响。在实验室研究中，未经过改良的 4:3 覆盖物与堆肥混合物在几个月后没有检测到 TCE。在建造的生物墙中，这种混合物将上游 TCE 浓度降低了约 90%，并在下游生成了乙烯，这表明成功地进行了还原脱氯。然而，也在下游检测到了更具毒性的降解产物氯乙烯 (VC)，其水平大约是最大污染物水平的十倍。这表明也发生了不完全降解。在实验室中，ZVI 减少了 VC 的形成。计算了垃圾填埋场有和没有生物墙的危害商数。生物墙的添加将危害商数降低了 88%。
