Combining chemical oxidation and bioremediation for petroleum polluted soil remediation by BC-nZVI activated persulfate

Total petroleum hydrocarbon (TPHs) has been posing a threat to soil health as its increasing production and application. For the better remediation and reclamation of TPHs polluted soil, the combined remediation by persulfate (PS) with biochar supported nano iron (BC-nZVI) was proposed and verified. In this study, the activators (BC-nVZI and nZVI) were synthesized through ferrous reducing by sodium borohydride under nitrogen with or without BC addition. The optimal concentration of 15% PS (w/w) was selected and applied to treat the TPHs polluted soil over 60 days. The TPHs degradation underwent two different stages, including chemical degradation (0th-6th day) and biodegradation (6th-60th day). To clarify the degradation process during remediation, the carbon chain transformation was tested. During the whole remediation period (0th-60th day), the long chain TPHs constantly degraded and transformed into short chain molecules in the BC-nZVI/PS groups. Furthermore, comparing with nZVI/PS groups, the BC-nZVI/PS groups could increase the soil microbial metabolic activities during the remediation period. Microbial analysis showed that the PS activation groups could significantly affect microbial abundance and structure. In BC-nZVI/PS groups, the microbial abundance recovered and TPHs-degradation bacterium increased over 60 days. This study gives an innovative technology for the TPHs polluted soil remediation which could achieve the goal for soil bioremediation after PS oxidation.