Treatment of Oil-Polluted Seawater by Modified Biochar Immobilized with Petroleum Degrading Bacteria

The pine sawdust biochar (BC) prepared by pyrolysis at 400 °C for 2 h was modified with different amounts of hydrochloric acid, among which 5H-BC modified by 5 mol·L−1 hydrochloric acid had the best oil adsorption efficiency in seawater. Petroleum degrading bacteria (PDB) were immobilized on 5H-BC, and the optimum conditions for immobilization were: inoculating 10% (v/v) PDB suspension, and fixing for 4 h at the speed of 180 r·min−1 on the shaking table. 5H-BC and 5H-BC-PDB were added to the simulated oil-polluted seawater. It was found that 5H-BC could quickly transfer the oil in seawater to BC phase through adsorption, but the total oil removal efficiency of 5H-BC-PDB was 23.5% higher than that of 5H-BC. High-throughput analysis of BC phase showed that 5H-BC-PDB contained more Acinetobacter and Pseudomonas, which indicated that BC immobilized with PDB was not only beneficial to the emulsification of oil, but also to the biodegradation of residual PAHs.