利用生物炭负载微生物修复石油烃-镉复合污染土壤

Remediation of petroleum hydrocarbon-cadmium co-contaminated soil by biochar loaded microorganisms

自四川省长宁某石油烃-重金属镉复合污染土壤中,筛选出1株具有重金属镉(Cd)抗性和石油烃降解能力的菌株,采用吸附法将菌株固定于玉米芯生物炭上制备成固定化微生物,并探讨固定化微生物技术(IMT)对土壤石油烃的降解效率以及重金属固定化效果。鉴定结果表明,成功筛选出的具有Cd抗性的石油烃降解菌经鉴定属于柠檬酸杆菌属(Citrobacter sp.)。实验结果表明:固定化微生物修复石油烃-重金属镉复合污染土壤60 d后,固定化微生物对石油烃降解率达51.25%,显著高于游离菌组(40.44%)、生物炭组(31.11%)和空白组(15.18%)(P<0.05);同时,固定化微生物能够高效固定土壤重金属Cd,使其从可交换态、有机结合态向残渣态转变,可使其残渣态与初始土壤相比增加6.68倍;固定化微生物组的土壤pH较初始出现轻微下降,但维持于8.42~8.75;此外,固定化微生物可显著增加土壤细菌数量(2.48×108 cfu·g−1)(P<0.05),土壤脱氢酶活性、过氧化氢酶活性以及多酚氧化酶活性(P<0.05)。因此,采用生物炭固定化微生物技术,可在高效降解石油烃的同时,提高重金属Cd固定化效果。该研究结果可为IMT技术修复石油烃-镉复合污染土壤提供参考。

A bacterial strain with heavy metal cadmium(Cd)resistance and petroleum hydrocarbons degradation ability was isolated from petroleum hydrocarbons and heavy metal Cd co-contaminated soil sampled from Changning,Sichuan province.The strain was fixed on corncob biochar by adsorption method to obtain immobilized microorganisms.The degradation efficiency of soil petroleum hydrocarbons and the immobilization effect of heavy metals by immobilized microorganism technology(IMT)were investigated.The results showed that the selected strain had the ability of Cd resistance and petroleum hydrocarbons degradation,which was identified as Citrobacter sp.Remediation of petroleum hydrocarbon-heavy metal Cd contaminated soil by immobilized microorganisms after 60 d,the degradation rate of petroleum hydrocarbons by immobilized microorganisms was 51.25%,significantly higher than that of the free bacteria group(40.44%),biochar group(31.11%)and blank group(15.18%)(P<0.05).At the same time,immobilized microorganisms could effectively immobilize the heavy metal Cd in the soil by changing the exchangeable and organic matter-bound species to the residual species,which could increase the residual species by 6.68 times compared with the initial soil.The addition of immobilized microorganisms caused slight decrease of soil pH compared with that in the initial stage,but maintained 8.42~8.75.Moreover,immobilized microorganisms significantly increased the number of soil bacteria(2.48×108 cfu·g−1)(P<0.05),soil dehydrogenase activity,catalase activity and polyphenol oxidase activity(P<0.05).Biochar immobilized microorganisms could not only efficiently degrade petroleum hydrocarbons,but also improve the heavy metal immobilization.The research results could provide theoretical support for remediation of petroleum-Cd co-contaminated soil by IMT.