Fan Xiangyu, Wang Hui, Luo Qishi, Ma Jianwei, Zhang Xihui
Department of Environmental Science and Engineering, Tsinghua University, Haidian District, Beijing 100084, PR China.
J Hazard Mater. 2007 Sep 5;148(1-2):29-37. doi: 10.1016/j.jhazmat.2007.01.144. Epub 2007 Feb 6.
In situ bioremediation is a safe and cost-effective technology for the cleanup of organic-contaminated soil, but its remediation rate is usually very slow, which results primarily from limited mass transfer of pollutants to the degrading bacteria in soil media. This study investigated the feasibility of adopting 2D non-uniform electric field to enhance in situ bioremediation process by promoting the mass transfer of organics to degrading bacteria under in situ conditions. For this purpose, a 2D non-uniform electrokinetic system was designed and tested at bench-scale with a sandy loam as the model soil and 2,4-dichlorophenol (2,4-DCP) as the model organic pollutant at two common operation modes (bidirectional and rotational). Periodically, the electric field reverses its direction at bidirectional mode and revolves a given angle at rotational mode. The results demonstrated that the non-uniform electric field could effectively stimulate the desorption and the movement of 2,4-DCP in the soil. The 2,4-DCP was mobilized through soil media towards the anode at a rate of about 1.0 cmd(-1)V(-1). The results also showed that in situ biodegradation of 2,4-DCP in the soil was greatly enhanced by the applied 2D electric field upon operational mode. At the bidirectional mode, an average 2,4-DCP removal of 73.4% was achieved in 15 days, and the in situ biodegradation of 2,4-DCP was increased by about three times as compared with that uncoupled with electric field, whereas, 34.8% of 2,4-DCP was removed on average in the same time period at the rotational mode. In terms of maintaining remediation uniformity in soil, the rotational operation remarkably excelled the bidirectional operation. In the hexagonal treatment area, the 2,4-DCP removal efficiency adversely increase with the distance to the central electrode at the bidirectional mode, while the rotational mode generated almost uniform removal in soil bed.
原位生物修复是一种用于清理有机污染土壤的安全且具有成本效益的技术，但其修复速率通常非常缓慢，这主要是由于污染物向土壤介质中降解细菌的传质受限所致。本研究调查了采用二维非均匀电场通过促进原位条件下有机物向降解细菌的传质来增强原位生物修复过程的可行性。为此，设计了一个二维非均匀电动系统，并在实验室规模上进行测试，以砂壤土作为模型土壤，以2,4 - 二氯苯酚（2,4 - DCP）作为模型有机污染物，采用两种常见操作模式（双向和旋转）。在双向模式下，电场会定期反转方向；在旋转模式下，电场会旋转给定角度。结果表明，非均匀电场可有效刺激2,4 - DCP在土壤中的解吸和移动。2,4 - DCP以约1.0 cmd(-1)V(-1)的速率通过土壤介质向阳极移动）。结果还表明，施加的二维电场根据操作模式极大地增强了土壤中2,4 - DCP的原位生物降解。在双向模式下，15天内2,4 - DCP的平均去除率达到73.4%，与未耦合电场时相比，2,4 - DCP的原位生物降解增加了约三倍，而在旋转模式下，在同一时间段内2,4 - DCP的平均去除率为34.8%。在保持土壤修复均匀性方面，旋转操作明显优于双向操作。在六边形处理区域，双向模式下2,4 - DCP的去除效率随距中心电极距离的增加而不利地增加，而旋转模式在土壤床层中产生几乎均匀的去除效果。
