Effective Treatment and Biodegradation Mechanism Analysis of Petroleum Hydrocarbon Wastewater by Immobilized Ochrobactrum sp. WY-4 on Iron-modified Biochar

Abstract

Total petroleum hydrocarbon (TPH) in wastewater has attracted widespread attention for its environmental and biological health hazards. In the research, WY-4 strains with diesel degradation ability isolated from contaminated soil and response surface methodology was used to optimize the degradation conditions of WY-4. Fe-modified biochar (FPB) was used as an immobilized carrier, the environmental factors affecting the degradation of immobilized bacteria (FPBM) were explored and the degradation effect of FPBM was evaluated on real TPH-contaminated wastewater. Furthermore, the potential degradation mechanisms and possible degradation pathways of TPH were also explored. The results demonstrated that WY-4 was identified as Ochrobactrum sp., and its optimal growth conditions were pH 6.8, temperature 28.8°C and NaCl concentration 9.47 g/L. The removal efficiency by FPBM on 10,000 mg/L diesel wastewater was 72.5% and on real TPH-contaminated wastewater was 76.75% in 7 d, which was significantly higher than the degradation effect of free bacteria. The degradation pathway of two representative pollutants, naphthalene and indole, in the real TPH-contaminated wastewater was referred to be the catechol metabolic pathway. The results highlighted the potential of FPB-immobilized bacteria for the remediation of TPH-contaminated wastewater in harsh environments and provided an effective strategy for green remediation treatment of TPH contamination.