铜污染场地土壤的原位电动强化修复

电动修复技术是一种新型的污染土壤修复技术,相关的理论和实验室小试研究较多,但鲜见野外现场条件下的原位修复研究。本研究以某电镀厂铜污染区为修复对象,以可生物降解的络合剂乳酸和柠檬酸为阴极池增强试剂,考察在原位条件下电动修复技术对土壤中铜的去除效率,并评估修复过程的电能消耗。结果表明:在电压梯度7.5 V·m-1,阴极池乳酸和柠檬酸浓度为0.5 mol·L-1,处理24 d(乳酸处理)和17 d(柠檬酸处理)的条件下,乳酸处理较柠檬酸处理电流要高、且阴阳极池溶液和土壤的pH、电导率变化要小;乳酸处理后土壤铜含量明显下降(阳极和阴极附近土壤铜去除率分别为52.6%和35.7%),而柠檬酸处理条件下阳极和阴极附近铜的去除效率分别为27.2%和-17.5%,这可能与其较低的电流和较短的处理时间有关。与现有文献比较,乳酸处理总能耗(15.7 kWh·m-3)处于较低水平,而Cu的去除率处于较高水平(35.7%~52.6%),优于文献报道的电动修复去除效率和电能消耗。

Field-scale electrokinetic remediation of heavy metal contaminated sites

Electrokinetics is an innovative technology for soil remediation.It has been widely studied in the laboratory and at bench-scales,although field-scale research is scarce.This study focused on the efficiency of field-scale electrokinetics for Cu removal from soil and subsequent evaluation of its energy consumption.A Cu-polluted site in an electroplate factory was chosen and 0.5 mol·L-1 each of lactic and citric acid was added to the catholyte as an enhancement reagent.Under a 7.5 V·m-1 voltage gradient and acidic processing(24 d for citric acid,17 d for lactic acid),a higher electric current was observed in lactic acid than citric acid treatment.Lactic acid treatment resulted in smaller changes in pH and electrical conductivity of both the electrolytes and bulk soil,with Cu removal percentages of 52.6% and 35.7% in soils near the anode and cathode regions,respectively.In contrast,Cu removal percentages of only 27.2% and -17.5% were observed in the soils near the anode and cathode for citric acid treatment,respectively;this was attributed to a lower electric current and shorter treatment time.The total energy consumption of lactic acid treatment was lower(15.7 kWh·m-3),and the Cu removal percentage was higher(35.7% to 52.6%) than that seen in prior work.