Biochar immobilized petroleum degrading consortium for enhanced granulation and treatment of synthetic oil refinery wastewater

This study investigated the effect of biochar immobilized consortium for enhanced biotreatment of oil refinery wastewater in sequencing batch reactors. The control reactor (R-0), and reactors with free bacterial consortium (R-1), biochar (R-2) and biochar immobilized consortium (R-3) were operated in parallel. Results illustrated that granulation was faster in R-2 and R-3, the proportion of granules >0.45 mm was almost 30% higher than the R-0 and R-1 during the first 45 days. R-3 exhibited optimum operational performance as highest removal efficiencies of COD (97.9%), oil (97.4%), NH4+-N (97.2%) and TN (90.2%) at the end of the experiment. Biochar enriched microbial richness and diversity whereas inoculated consortium positively modulated the community structures. Higher abundance of inoculated Rhodococcus (4.81%) bacteria in R-3 suggested successful formation of functional strains in the granular sludge. It concludes that the application of biochar immobilized consortium is a better choice for the treatment of refinery wastewater.