完全对称电场对电动-微生物修复石油污染土壤的影响

针对石油这种非极性复杂有机污染物难以去除的特点，以含油量为50 mg/g的石油污染土壤为研究对象，运用行/列循环切换方式,每5 min切换一次电极极性，建立空间和场强上完全对称的电场，旨在研究完全对称电场条件下电动-微生物联合修复对石油污染物去除率的影响. 对土壤有效氮、有效磷、有效钾等营养物含量以及降解菌数量在电场作用下的变化进行比较. 结果表明，1 V/cm的电压梯度下，土壤中的w(有效氮),w(有效磷)和w(有效钾)分别为初始值的1.3，1.6和1.2倍；同时，在电场作用和电极极性切换条件下，土壤的pH为6.3±0.2，温度升高2～3 ℃，石油降解菌的数量增加，当处理时间为20 d时，降解菌数量最大值达2.3×109 　CFU/mL，进而提高了石油的去除率. 烷烃在电动处理下降解速率加快，60 d烷烃去除率达到15.73%. 经过60 d的电动-微生物修复，石油去除率达到33.42%，是对照组的2.4倍. 

Effects of Completely Symmetrical Electric Field on Electro-Bioremediation of Oil Contaminated Soil

Petroleum, a complex, non-polar organic pollutant that is difficult to be degraded, was employed as a target organic pollutant at the level of 50 mg/g (mass of petroleum/mass of dry soil). An electrode control apparatus capable of reversing the polarity of the electric field every 5 min by the mode of rows/columns was designed. Therefore, the apparatus established a completely symmetric electric field both in space and field intensity. The aim was to explore the effect of electro-bioremediation on the removal rate of oil contaminants using a completely symmetric electric field. The variations of available nitrogen (AN), available phosphorus (AP) and available potassium (AK) and population of oil-degrading bacteria were compared under the electric field. Results indicated that under an electric field gradient of 1 V/cm, the contents of AN, AP and AK were 1.3, 1.6 and 1.2 times higher than the original contents, respectively. In addition, the electric field effect and the electrode polarity switching led to a soil pH close to neutral (6.3±0.2), and a temperature increase of 2-3 ℃, and thus the number of oil-degrading bacteria increased with a maximum value of 2.3×109 CFU/mL under the treating time of 20 d. These factors enhanced the removal rate of oil from the soil. The degradation rate of alkane accelerated, with a removal rate of 15.73% in 60 d. The removal efficiency of oil was 35.22% after 60 days, which was 2.4 times that of the control test.