Bioremediation of Petroleum-Contaminated Soils With Pyrolysis Biochar: TPH Removal, Multifunctionality, and Microecological Restoration

Abstract

This study evaluated the remediation effects of six biochars produced from spent mushroom substrate (SMS), wheat straw (WS), and cattle dung (CD) at pyrolysis temperatures of 300°C and 500°C on petroleum-contaminated soil. As the pyrolysis temperature increased from 300°C to 500°C, the biochar yield decreased from 56.10%–64.81% to 30.63%–41.98%, whereas the pH value and available phosphorus content of biochars increased from 6.49–8.94 and 175.6–347.4 to 9.84–10.19 and 350.4–3660.8 mg/kg, respectively. Biochar amendments significantly enhanced total petroleum hydrocarbon (TPH) degradation, with the 300°C-pyrolyzed CD biochar (CDA) showing the best performance (33.01% of TPH degradation rate, 76.43% higher than the control group, CK). Biochar application significantly enhanced soil multifunctionality (MF), with the highest improvement observed in CDA (MF = 0.79) and CDB (MF = 0.48) treatments, which were substantially higher than that of the control (CK, 0.28). Biolog EcoPlate analysis revealed that biochar treatments exhibited significantly higher microbial metabolic activity and diversity index and enhanced the utilization of carbohydrates, amines, and carboxylic acids. These findings indicated that agricultural waste-derived biochars can effectively facilitate the ecological remediation of petroleum-contaminated soils through synergistic improvements in soil physicochemical properties and microbial community functions, providing a feasible solution for agricultural waste recycling and contaminated soil remediation.