Long-lasting degradation of long-chain alkanes through activating Bacillus-like microbes after Fenton pre-oxidation in soil

Abstract

To explore the effects and mechanisms of long-lasting degradation of long-chain alkanes (C₂₅-C₃₀) in petroleum-contaminated soil, a solid iron catalyst prepared by adding different proportions of (5 % and 15 % (w/w)) chitosan (CS) was used for Fenton pre-oxidation experiment. Bioremediation experiments were performed for 100 days after pre-oxidation. The results indicated that the degradation for long-chain alkanes and Total Petroleum Hydrocarbons (TPH) were 76.95 % and 76.89 %, respectively. Furthermore, long-lasting degradation of long-chain alkanes was achieved by activating Bacillus-like microbes. In each biodegradation cycle, the long-chain alkanes degradation in the active control group increased by 77.39 mg/kg, 76.74 mg/kg, 36.88 mg/kg, and 76.51 mg/kg compared to the previous cycle. Besides, the half-life of long-chain alkanes was 131 days shorter in the active control group than in the inactive control group. Higher microbial enzyme activity for degrading long-chain alkanes was observed after Fenton pre-oxidation because the expression of alkane metabolism genes was activated by the high consumption of dissolved organic carbon. Finally, the dominant bacterial genera in the active control group shifted predominantly to Paenibacillus (13.26 %), Acinetobacter (8.02 %), and Microbacterium (17.64 %). Therefore, this study possesses significant engineering application value.