In situ remediation of low-permeability soils contaminated with trichloroethylene (TCE) is challenging due to limited mass transfer and low bioavailability in clay soils. The electrokinetic-enhanced bioremediation (EK-BIO) system offers a promising solution by combining electrokinetics with bioremediation to address these challenges. While previous studies have demonstrated microbial succession and TCE removal, the long-term performance of dechlorination and interactions between electrode reactions and anaerobic dechlorination remain unclear. This study constructed five one-dimensional columns, each operated for a different period (28, 42, 56, 84 and 138 days) to explore spatial and temporal dechlorination patterns. Continuous TCE degradation was achieved, with 46.52 % of TCE recovery. Prolonged electrokinetic operation accelerated the first-step dehalogenation (TCE to DCE). Although Dehalococcoides was widespread at 138 days (2.30–5.74 %), oxygen exposure led to irreversible damage, necessitating secondary inoculation. The presence of aerobic bacteria (Comamonas and Pseudomonas) suggested the formation of aerobic detoxification pathways in electrode chambers. Gene expression analysis (tceA, vcrA and Dhc16S) further confirmed the loss of 2nd and 3rd step dehalogenation (DCE to ethene) over time. These findings demonstrate that secondary inoculation and alternative aerobic pathways can sustain long-term biodegradation in the EK-BIO system. This study highlights the potential of the EK-BIO system for effective remediation of TCE-contaminated low-permeability soils, supporting its field application.

中文翻译：

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通过电动增强生物修复技术在低渗透性土壤中三氯乙烯脱毒：长期可行性和时空模式


由于粘土中的传质有限且生物利用度低，受三氯乙烯 （TCE） 污染的低渗透性土壤的原位修复具有挑战性。电动增强生物修复 （EK-BIO） 系统通过将电动与生物修复相结合来应对这些挑战，提供了一种很有前途的解决方案。虽然以前的研究表明微生物演替和 TCE 去除，但脱氯的长期性能以及电极反应与厌氧脱氯之间的相互作用仍不清楚。本研究构建了五个一维柱，每个柱运行不同的时期 （28、42、56、84 和 138 天），以探索空间和时间脱氯模式。实现了连续的 TCE 降解，TCE 回收率为 46.52%。长时间的电动操作加速了第一步脱卤（TCE 到 DCE）。尽管 Dehalococcoides 在 138 天 （2.30-5.74%） 时广泛存在，但氧气暴露会导致不可逆的损伤，需要二次接种。需氧细菌 （Comamonas 和 Pseudomonas） 的存在表明在电极室中形成了有氧解毒途径。基因表达分析 （tceA、vcrA 和 Dhc16S） 进一步证实了随着时间的推移，第 2 步和第 3 步脱卤 （DCE 到乙烯） 的损失。这些发现表明，二次接种和替代好氧途径可以维持 EK-BIO 系统中的长期生物降解。本研究强调了 EK-BIO 系统有效修复 TCE 污染的低渗透性土壤的潜力，支持其现场应用。