化学氧化后深层土壤中多环芳烃的缺氧微生物降解

Anoxic biodegradation of polycyclic aromatic hydrocarbons( PAHs)in aged deep soil pretreated with chemical oxidation

土壤中多环芳烃(PAHs)的化学氧化与微生物联合降解备受关注,但已有的研究主要集中在化学氧化与好氧微生物联用方面,与缺氧微生物联用研究较少。通过对过氧化氢氧化后的土壤进行接种和缺氧培养,考察化学氧化后深层土壤中PAHs缺氧微生物降解的可行性。结果表明:过氧化氢氧化后,16种PAHs降解了33.3%~95.9%,但土壤中细菌数量也明显减少,细菌数量的基因拷贝数减少了3.5个数量级;缺氧培养180 d后,添加营养盐可使微生物数量明显恢复,在同时添加营养盐和电子受体(硫酸盐)时微生物数量恢复程度更高;单独添加营养盐或电子受体不能明显促进PAHs降解,同时添加营养盐和电子受体能够促进PAHs降解,且同时添加营养盐和电子受体时,接种土壤中3环和部分4环PAHs(荧蒽和芘)的降解率显著高于未接种土壤。总体上,缺氧微生物降解可使PAHs去除率在化学氧化的基础上提高15%左右。

Integrated chemical-biological treatment of polycyclic aromatic hydrocarbons(PAHs)contaminated soil has received much attention.However,previous studies mainly focused on the remediation of soils contaminated with PAHs using oxidation treatment coupled with aerobic biodegradation,rather than anoxic biodegradation.In order to study the feasibility of applying combined chemical oxidation and anoxic biodegradation method to remediate PAHs contaminated soil,the anoxic culture of the soil oxidized by hydrogen peroxide was carried out.It was found that the removal efficiencies of 16 PAHs ranged from 33.3%to 95.9%after hydrogen peroxide oxidation,but the application of hydrogen peroxide resulted in a significant decrease of the number of bacteria in the soil,and the gene copy number of total bacteria in soil decreased by 3.5 orders of magnitude.However,bacterial numbers could be significantly recovered after 180 days of anoxic incubation in the treatment added with nutrients,and higher levels of bacteria were observed in treatments with nutrients and electron acceptor(sulfate)in inoculated soil.The use of nutrients or electron receptor(sulfate)alone could not enhance the biodegradation of PAHs obviously,but the application of both nutrients and electron acceptor could result in obviously biodegradation of PAHs.Moreover,higher biodegradation efficiency was observed for 3-rings and partial 4-rings PAHs(fluoranthene and pyrene)in inoculated soil than that of non-inoculated soil in treatment where both nutrients and electron acceptor were added.Overall,a further PAHs removal of about 15%was observed after anoxic biological treatment compared with chemical oxidation treatment alone.