Immobilized enzyme with sustainable chestnut biochar to remediate polycyclic aromatic hydrocarbons contaminated soils

Polycyclic aromatic hydrocarbons (PAHs) contaminated soil severely and are difficult to remediate. In this study, acid-modified chestnut inner shell biochar with abundant pore channels was used as the main raw materials for the immobilization of white-rot fungal crude enzyme. The maximum immobilization rate of crude enzymes (97.25%+/- 6.20%) could be achieved under the optimal conditions of 24 h immobilization of 10 U/mL crude enzymes by 1 g biochar at 25celcius and pH = 5. Meanwhile, immobilization improved the stability of the crude enzyme. The relative activity of the immobilized crude enzyme increased by 59.32% and 49.73% (compared to the free crude enzymes) after 5 weeks of storage at 4 degrees C and 25 degrees C, respectively. It has been verified that chestnut-based immobilized crude enzyme can degrade 37% of benzo[a]pyrene in 10 days for PAHs-contaminated soils. An efficient, feasible, and low-cost remediation method for PAHs-contaminated soils was explored, which provides technical support for the application of crude enzymes in organic contaminated soils.

Automated summary

In this study, acid-modified chestnut inner shell biochar was used to immobilize white-rot fungal crude enzyme for the remediation of PAHs-contaminated soil. The maximum immobilization rate of crude enzyme reached 97.25% under optimal conditions. Immobilization enhanced the stability of the crude enzyme, with a relative activity increase of 59.32% and 49.73% after 5 weeks of storage at 4 degrees C and 25 degrees C, respectively. The chestnut-based immobilized crude enzyme successfully degraded 37% of benzo[a]pyrene in 10 days for PAHs-contaminated soils. Overall, this study explores an efficient, feasible, and low-cost remediation method for PAHs-contaminated soils and provides technical support for the application of crude enzymes in organic contaminated soils.