School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Water Res. 2011 Nov 1;45(17):5365-74. doi: 10.1016/j.watres.2011.06.022. Epub 2011 Jun 30.
The development of bioreactive sediment caps, in which microorganisms capable of contaminant transformation are placed within an in situ cap, provides a potential remedial design that can sustainably treat sediment and groundwater contaminants. The goal of this study was to evaluate the ability and limitations of a mixed, anaerobic dechlorinating consortium to treat chlorinated ethenes within a sand-based cap. Results of batch experiments demonstrate that a tetrachloroethene (PCE)-to-ethene mixed consortium was able to completely dechlorinate dissolved-phase PCE to ethene when supplied only with sediment porewater obtained from a sediment column. To simulate a bioreactive cap, laboratory-scale sand columns inoculated with the mixed culture were placed in series with an upflow sediment column and directly supplied sediment effluent and dissolved-phase chlorinated ethenes. The mixed consortium was not able to sustain dechlorination activity at a retention time of 0.5 days without delivery of amendments to the sediment effluent, evidenced by the loss of cis-1,2-dichloroethene (cis-DCE) dechlorination to vinyl chloride. When soluble electron donor was supplied to the sediment effluent, complete dechlorination of cis-DCE to ethene was observed at retention times of 0.5 days, suggesting that sediment effluent lacked sufficient electron donor to maintain active dechlorination within the sediment cap. Introduction of elevated contaminant concentrations also limited biotransformation performance of the dechlorinating consortium within the cap. These findings indicate that in situ bioreactive capping can be a feasible remedial approach, provided that residence times are adequate and that appropriate levels of electron donor and contaminant exist within the cap.
生物反应性沉淀层的发展，即将能够转化污染物的微生物置于原位沉淀层内，为可持续处理沉积物和地下水污染物提供了一种潜在的补救设计。本研究的目的是评估混合厌氧脱氯菌在基于砂的沉淀层中处理氯代乙烯的能力和局限性。批处理实验结果表明，当仅提供取自沉积物柱的沉积物孔隙水时，四氯乙烯（PCE）-乙烯混合菌能够完全将溶解相 PCE 脱氯为乙烯。为了模拟生物反应性沉淀层，将接种有混合培养物的实验室规模砂柱与上流沉积物柱串联，并直接供应沉积物流出物和溶解相氯代乙烯。当不向沉积物流出物中添加添加剂时，混合菌不能在保留时间为 0.5 天的情况下维持脱氯活性，这表现为顺式-1,2-二氯乙烷（顺式-DCE）脱氯为氯乙烯的损失。当向沉积物流出物中供应可溶电子供体时，在保留时间为 0.5 天的情况下观察到顺式-DCE 完全脱氯为乙烯，表明沉积物流出物缺乏足够的电子供体以维持沉淀层内的活性脱氯。污染物浓度的升高也限制了沉淀层内脱氯菌的生物转化性能。这些发现表明，原位生物反应性封盖可以是一种可行的补救方法，前提是停留时间足够长，并且封盖内存在适当水平的电子供体和污染物。
