Decomposition of oil refinery sludge using E+-Ozonation process for carbon source releasing and TPH removal

To utilize carbon source and decompose the petroleum hydrocarbon substances simultaneously, adding the electrolysis to ozonation (E + -Ozonation) was employed to deal with hazardous activated petroleum waste sludge (P-sludge). It was found that E + -Ozonation could accelerate the ozone utilization and hydroxyl radical (·OH) generation rate. Soluble chemical oxygen demand (SCOD) increased around 16.3 times than the control one (from 471 to 7700 mg/L). The potential carbon source, such as the short-chain carbon of acetate and propionate, increased from 50 to 1088 mg/L and from 27 to 614 mg/L respectively, and approximately accounted for a quarter of total SCOD. Total petroleum hydrocarbon (TPH) decomposition was observed with a much higher removal rate of 84.3% simultaneously, and the substances with the function group of C=C and C–C bonds decomposed greatly. The long- and medium-chain substances in TPH were converted into the short-chain substances (90% of C 28 –C 40 of hydrocarbons was removed, while C 10 –C 18 increased by 13.8%). E + -Ozonation process could be one of the promising methods for P-sludge decomposition through carbon source releasing and TPH removal. Graphical abstract