A continuous-flow bioelectrochemical reactor was developed in a previous study to address the bioremediation of groundwater contaminated by trichloroethene (TCE). The present report investigated the applicability of the same system in the presence of Cr(VI) and its possible inhibitory effect on dehalorespiring bacterial populations. Preliminary batch tests were performed at the optimal cathodic reducing potential for the reductive dechlorination (RD) of TCE (-0.65 V vs. the standard hydrogen electrode) with two different dechlorinating microorganism consortia. The results demonstrated that Cr(VI) removal efficacy was increased by microorganisms that had been previously acclimatised to Cr(VI). Specifically, Cr(VI) was completely reduced only in the presence of acclimated microorganisms. The presence of chromate negatively affected RD performance, by either (i) limiting the TCE transformation to cis-dichloroethene at lower concentrations, or (ii) completely inhibiting RD at higher concentrations. In contrast, after the acclimation period, RD was extended down to vinyl chloride, which is the main TCE daughter product. Finally, the continuous flow reactor was fed by synthetic groundwater contaminated with TCE (50 µM) and Cr(VI) (45 µM), and the experimental results showed that Cr(VI) was completely reduced under RD conditions. Moreover, TCE removal was complete, with vinyl chloride and ethene as the main intermediates, thus indicating that chromate inhibition was decreased by Cr(VI) removal.

中文翻译：

---

铬酸盐归宿和生物电化学系统中氯化溶剂修复的影响

在先前的研究中开发了一种连续流生物电化学反应器，以解决受三氯乙烯 (TCE) 污染的地下水的生物修复。本报告调查了同一系统在 Cr(VI) 存在下的适用性及其对脱盐细菌种群的可能抑制作用。使用两种不同的脱氯微生物聚生体在 TCE 还原脱氯 (RD) 的最佳阴极还原电位（-0.65 V 与标准氢电极）下进行初步批量测试。结果表明，先前已适应 Cr(VI) 的微生物可提高 Cr(VI) 的去除效果。具体而言，只有在适应环境的微生物存在下，Cr(VI) 才会完全减少。铬酸盐的存在对 RD 性能产生负面影响，通过 (i) 在较低浓度下限制 TCE 转化为顺式二氯乙烯，或 (ii) 在较高浓度下完全抑制 RD。相比之下，在适应期之后，RD 向下延伸到氯乙烯，这是主要的 TCE 子产品。最后，连续流反应器由被 TCE (50 µM) 和 Cr(VI) (45 µM) 污染的合成地下水供给，实验结果表明，在 RD 条件下，Cr(VI) 被完全还原。此外，以氯乙烯和乙烯为主要中间体的三氯乙烯去除完全，这表明铬酸盐抑制通过去除 Cr(VI) 降低。RD 延伸到氯乙烯，这是主要的 TCE 子产品。最后，连续流反应器由被 TCE (50 µM) 和 Cr(VI) (45 µM) 污染的合成地下水供给，实验结果表明，在 RD 条件下，Cr(VI) 被完全还原。此外，以氯乙烯和乙烯为主要中间体的三氯乙烯去除完全，这表明铬酸盐抑制通过去除 Cr(VI) 降低。RD 延伸到氯乙烯，这是主要的 TCE 子产品。最后，连续流反应器由被 TCE (50 µM) 和 Cr(VI) (45 µM) 污染的合成地下水供给，实验结果表明，在 RD 条件下，Cr(VI) 被完全还原。此外，以氯乙烯和乙烯为主要中间体的三氯乙烯去除完全，这表明铬酸盐抑制通过去除 Cr(VI) 降低。