Department of Chemical Engineering and Applied Chemistry, University of Toronto , 200 College Street, Toronto, Ontario M5S 3E5N, Canada.
Environ Sci Technol. 2014 May 20;48(10):5770-9. doi: 10.1021/es404122y. Epub 2014 May 7.
The use of enhanced in situ anaerobic bioremediation (EISB) and bioaugmentation in fractured bedrock is limited compared to its use in granular media. We evaluated EISB for the treatment of trichloroethene (TCE)-impacted groundwater in fractured carbonate rock at a site in Southern Ontario, Canada, with cool average groundwater temperature (∼ 13 °C). Borehole-connectivity, contaminant concentrations, and groundwater properties were investigated. Changes in dechlorinating and nondechlorinating populations (fermenters, acetogens, methanogens, and sulfate reducers) were assessed via quantitative PCR (qPCR). During biostimulation with ethanol, concentrations of TCE daughter products cis-dichloroethene (cDCE) and vinyl chloride (VC) decreased in association with an enrichment of vcrA (VC reductive dehalogenase)-carrying Dehalococcoides, whereas ethene production was only moderate. Following bioaugmentation with the mixed dechlorinating culture KB-1, greater concentrations of chloride-a product of dechlorination-was observed in most wells; in addition, ethene production increased significantly in monitoring well locations that had strong hydraulic connectivity to the groundwater recirculation system, while Dehalococcoides and vcrA concentrations did not appreciably vary. Interestingly, increases of 3-4 orders of magnitude of an ethanol-fermenting Bacteroidetes population also present in KB-1 were correlated to improved conversion to ethene, an observation which suggests there could be a causal relationship-for example, better syntrophy and/or synergy among bacterial populations.
与在颗粒介质中相比，增强型原位厌氧生物修复（EISB）和生物增强在基岩裂隙中的应用受到限制。我们在加拿大安大略省南部的一个地点评估了 EISB 对受三氯乙烯（TCE）污染的基岩裂隙地下水的处理效果，该地点的地下水温度较低（约 13°C）。我们研究了钻孔连通性、污染物浓度和地下水特性。通过定量 PCR（qPCR）评估了脱氯和非脱氯种群（发酵菌、乙酰菌、产甲烷菌和硫酸盐还原菌）的变化。在乙醇生物刺激期间，TCE 子代产物顺式-二氯乙烯（cDCE）和氯乙烯（VC）的浓度降低，同时携带 VC 还原性脱卤酶（vcrA）的 Dehalococcoides 富集，而乙烯的产量仅适中。在使用混合脱氯培养物 KB-1 进行生物增强后，大多数井中观察到更多的氯离子浓度——脱氯的产物；此外，在与地下水再循环系统具有强水力连通的监测井位置，乙烯的产量显著增加，而 Dehalococcoides 和 vcrA 浓度没有明显变化。有趣的是，在 KB-1 中也存在的乙醇发酵拟杆菌种群的数量增加了 3-4 个数量级，这与向乙烯的转化率提高相关，这一观察结果表明可能存在因果关系——例如，细菌种群之间更好的共生和/或协同作用。
