完全对称电场对电动-微生物修复石油污染土壤的影响

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

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20d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.

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.