电动力修复土霉素污染土壤的效果及机理研究

Effects and Mechanism Study of Electrokinetic Remediation of Soil Polluted by Oxytetracycline

由抗生素引起的细菌耐药性问题日益严峻。为了建立一种高效去除土壤中抗生素和耐药菌污染的方法,文章以土霉素为特征污染物,开展了电动力修复污染土壤的实验研究。经过7 d的电动力修复处理,土壤中土霉素平均去除率达40.8%,这主要源自电场的直接和间接作用、土壤中土著微生物的作用以及水解等过程。经电动力处理后,土壤中的细菌总数(2.42×10^6CFU/g)与空白土壤(2.45×10^6CFU/g)的差异不大,而抗土霉素菌数由空白土壤中的3.73×10^6CFU/g降低到2.24×10^6CFU/g(p<0.05),抗土霉素菌的平均抑制率为15.3%。电动力修复系统中,四环素的降解主要归因于土壤微生物、电场作用下的直接氧化和电极反应产生活性物质的间接氧化以及土壤中的水解等作用。门水平和纲水平的细菌分类研究结果表明,电动力处理前后土壤中的优势菌群发生了改变。综上,电动力修复技术是治理土壤抗生素和耐药菌污染的有效手段。

Antibiotics and corresponding antibiotic resistance is becoming more and more serious.In order to establish an effective way to remove antibiotics and antibiotic-resistant bacteria in soil,electrokinetic experiment was carried out to remediate contaminated soil with oxytetracycline(OTC)as a characteristic pollutant.By reversing the polarity of the power every12 h,it is ensured that the pH of electrolytes and soil is in the right range,which ensures both the smooth progress of electrochemical process and microbial reaction.After 7-day electrokinetic remediation,the average removal rate of OTC in soil reached 40.8%,which is mainly due to the direct and indirect effects of electric field,the role of indigenous microorganisms in soil and hydrolysis process.In the treatment without electric field,the total number of bacteria and the number of anti-OTC bacteria in soil samples at 0~2 cm were 2.45×10^6 and 3.73×10^6 CFU/g,respectively,which were significantly higher than those in electrokinetic treatment group(2.42×10^6,2.24×10^6 CFU/g)(p<0.05).The average inhibition rate of anti-OTC bacteria was 15.3%.In the electrokinetic remediation system,the degradation of oxytetracycline could be attributed to the action of microorganism in soil,direct oxidation under electric field and indirect oxidation by electrode reaction,as well as hydrolysis in soil.The electrokinetic remediation can significantly remove antibiotics and antibiotic-resistant bacteria in contaminated soil,which will provide a new effective and feasible technology for the current remediation of antibiotics and drug-resistant bacteria worldwide.