Harnessing microbial synergy: A comprehensive evaluation of consortia-mediated bioremediation strategies for petroleum refinery wastewater treatment

The growing global demand for energy has led to the expansion of oil and gas industries, putting our environment at risk of pollution. The unregulated discharge of petroleum refinery wastewater (PRW), accidental spills, and ineffective policies have led to severe contamination and increased environmental and health consequences making management and mitigation a priority for everyone. This study evaluated the performance of two biological treatment methods - free-cell microbial consortium and immobilized microbial system - in the remediation of PRW using physicochemical, 2,6-dichlorophenollindophenol (DCPIP), Gas chromatography (GC) and Fourier-transform infrared spectroscopy (FTIR) techniques. The effectiveness of the two microbial consortia in reducing concentrations of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in the wastewater was compared to determine the most efficient method for treating PRW. The physicochemical result revealed cocktails of contaminants while Alcaligenes faecalis strain SLW6 and strain IAM 12369, and Providencia vermicola strain OP1, showed high degradative capacities. The immobilized and free-cell microbial systems significantly reduced the concentrations of PAHs, and HMs pollutants in the wastewater, with the former showing slightly better removal efficiencies for PAHs (92.97 % vs 87.34 %), heavy metals (99.17 %), and oil weight reduction (87.76 % vs 82.25 %) after the 28-day biodegradation period respectively. GC and FTIR analyses confirmed the formation of various degraded products, demonstrating the microbial consortia's effectiveness in degrading complex organic compounds. The findings highlight the potential of microbial consortia-mediated remediation as an eco-friendly and sustainable approach for treating PRW, contributing to protecting water resources and promoting sustainable practices in the petroleum industry.