Biochar-Assisted Catalytic Pyrolysis of Oily Sludge to Attain Harmless Disposal and Residue Utilization for Soil Reclamation

Pyrolysis of oily sludge (OS) is a feasible technology to match the principle of reduction and recycling; however, it is difficult to confirm the feasible environmental destination and meet the corresponding requirements. Therefore, an integrated strategy of biochar-assisted catalytic pyrolysis (BCP) of OS and residue utilization for soil reclamation is investigated in this study. During the catalytic pyrolysis process, biochar as a catalyst intensifies the removal of recalcitrant petroleum hydrocarbons at the expense of liquid product yield. Concurrently, biochar as an adsorbent can inhibit the release of micromolecular gaseous pollutants (e.g. HCN, H₂S, and HCl) and stabilize heavy metals. Due to the assistance of biochar, pyrolysis reactions of OS are more likely to occur and require a lower temperature to achieve the same situation. During the soil reclamation process, the obtained residue as a soil amendment can not only provide a carbon source and mineral nutrients but can also improve the abundance and diversity of microbial communities. Thus, it facilitates the plant germination and the secondary removal of petroleum hydrocarbons. The integrated strategy of BCP of OS and residue utilization for soil reclamation is a promising management strategy, which is expected to realize the coordinated and benign disposal of more than one waste.