Bioremediation of petroleum-contaminated soil by semi-aerobic aged refuse biofilter: Optimization and mechanism

Abstract

Petroleum-contaminated soil (PCS) is a global environmental issue. An effective remediation technique is urgently needed to address this problem. This study applied a semi-aerobic aged refuse biofilter (SAARB) to the decontamination and remediation of PCS. The effects of petroleum content, surfactant content, and water content on oil removal efficiency were studied, and the operation conditions were optimized using the response surface method. Results showed that contents of petroleum and water that were too high or too low depressed total petroleum hydrocarbon (TPH) removal. The presence of surfactant markedly reduced the TPH removal efficiency. The optimal operation conditions were the ratio of aged refuse to PCS = 1.6; water content = 41%; and petroleum content = 3.8%. The TPH removal efficiencies under optimized conditions and during a confirmatory experiment were 59.89% and 51.38%, respectively. PCS contained an abundance of polycyclic aromatic hydrocarbons and macro molecular alkanes, and these organic compounds were considerably removed by SAARB treatment. The microbial community exhibited a marked change at both phylum level and genus level after 3 months of remediation in the PCS. At the genus level, norank_f_SS1–B-06-26 became the most dominant; further isolation and verification experiments for its ability to degrade petroleum are needed. In addition, the abundance of norank_o_Saccharimonadales, Aquabacterium, Hydrogenophaga, and norank_f_Saccharimonadaceae, which can degrade hydrocarbons, also increased. This study provides a theoretical reference for SAARB application in the remediation of PCS.