Dechlorination of Trichloroethene in a Continuous-Flow Bioelectrochemical Reactor: Effect of Cathode Potential on Rate, Selectivity, and Electron Transfer Mechanisms
Dechlorination of Trichloroethene in a Continuous-Flow Bioelectrochemical Reactor: Effect of Cathode Potential on Rate, Selectivity, and Electron Transfer Mechanisms
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DOI：
10.1021/es202262y
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发表时间：
2011-10-01
影响因子：
11.4
通讯作者：
Majone, Mauro
中科院分区：
文献类型：
--
作者：
Aulenta, Federico;Tocca, Lorenzo;Majone, Mauro
脱氯细菌可以使用极化石墨阴极作为还原脱氯中的直接电子供体这一令人兴奋的发现促使人们对新型生物电化学修复方法的开发进行研究。在这项工作中，我们研究了用于处理三氯乙烯（TCE）的生物电化学反应器的性能。该反应器在不同的恒电位控制的阴极电位下连续运行约570天，相对于标准氢电极，阴极电位范围为-250 mV至-750 mV。 TCE 脱氯的速率和程度，以及对可用电子的竞争，高度依赖于设定的阴极电势。当阴极控制在-250 mV时，没有发生非生物氢产生，TCE脱氯（主要是顺式DCE和VC）很可能通过直接细胞外电子转移维持，以15.5 +/- 1.2 mu mol e(-)/L d的平均速率进行。在该阴极处，潜在的产甲烷作用几乎被完全抑制，脱氯作用占系统中流动的电流（15.0 +/- 0.8 μA）的 94.7 +/- 0.1%。尽管存在非常活跃的产甲烷作用（占电流的 60% 以上），但在阴极电位低于 -450 mV 时，TCE 脱氯率较高（高达 64 +/- 2 mu mol e(-)/L d）。值得注意的是，即使不随进料供应有机碳源，生物电化学反应器也表现出稳定且可重复的性能，证实了长期可行性。
The exciting discovery that dechlorinating bacteria can use polarized graphite cathodes as direct electron donors in the reductive dechlorination has prompted investigations on the development of novel bioelectrochemical remediation approaches. In this work, we investigated the performance of a bioelectrochemical reactor for the treatment of trichloroethene (TCE). The reactor was continuously operated for about 570 days, at different potentiostatically controlled cathode potentials, ranging from -250 mV to -750 mV vs standard hydrogen electrode. The rate and extent of TCE dechlorination, as well as the competition for the available electrons, were highly dependent on the set cathode potential. When the cathode was controlled at -250 mV, no abiotic hydrogen production occurred and TCE dechlorination (predominantly to cis-DCE and VC), most probably sustained via direct extracellular electron transfer, proceeded at an average rate of 15.5 +/- 1.2 mu mol e(-)/L d. At this cathode, potential methanogenesis was almost completely suppressed and dechlorination accounted for 94.7 +/- 0.1% of the electric current (15.0 +/- 0.8 mu A) flowing in the system. A higher rate of TCE dechlorination (up to 64 +/- 2 mu mol e(-)/L d) was achieved at cathode potentials lower than -450 mV, though in the presence of a very active methanogenesis which accounted for over 60% of the electric current. Remarkably, the bioelectrochemical reactor displayed a stable and reproducible performance even without the supply of organic carbon sources with the feed, confirming long-term viability.