Remediation of PAHs contaminated soil enhanced by nano-zero-valent iron combined with white rot fungi Peniophora incarnata

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are hazardous organic contaminants commonly found in soils. This study investigated an integrated remediation approach combining white rot fungal augmentation and nano-zero-valent iron (nZVI) activated persulfate oxidation to enhance the degradation of PAHs in soil. The white rot fungus Peniophora incarnata demonstrated efficient degradation of lower molecular weight PAHs including phenanthrene (91% removal) and anthracene (71% removal) in liquid culture, but had limited degradation of high molecular weight benzo[a]pyrene (35% removal). Inoculation of P. incarnata in non-sterilized soil led to 54% phenanthrene and 46% anthracene removal after 42 days. Co-inoculation with Pseudomonas aeruginosa slightly improved the degradation by 15% and 13%, respectively. However, benzo[a]pyrene removal was negligible through bioremediation alone. Direct nZVI/persulfate oxidation removed 55–75% of lower molecular weight PAHs and 68% of benzo[a]pyrene in soil. Integrated treatment combining nZVI/persulfate oxidation followed by P. incarnata inoculation resulted in 92–96% degradation of phenanthrene, anthracene and benzo[a]pyrene after 42 days, which was significantly higher than either approach alone. The enhanced PAH removal was attributed to the coupled effects of chemical oxidation and microbial degradation. P. aeruginosa is capable of directly metabolizing and mineralizing lower molecular weight PAHs such as phenanthrene and anthracene. The presence of this additional PAH-degrading bacterium likely contributed to the increased degradation observed. Overall, the sequential nZVI/persulfate and fungal treatment provides an effective and sustainable option for remediating soils co-contaminated with PAHs and other persistent organics. Further research should optimize treatment parameters and evaluate long-term impacts on soil quality.