Bioremediation of Petroleum Refinery Effluent Using Bacterial Co-Culture: Assessment of Improved Effluent Quality Through Phytotoxicity Studies.

The detoxification and degradation of petroleum refinery effluent (PRE) pose critical worldwide environmental challenges, with limited studies investigating the synergistic efficiency of bacterial consortia in enhancing bioremediation outcomes. This study investigates PRE biodegradation utilizing Acinetobacter calcoaceticus, Bacillus subtilis, and Pseudomonas putida, all separately and as bacterial co-culture (BCC) at a 1:1:1 ratio (v/v/v), employing physicochemical characterization and phytotoxicity analyses with Vigna radiata. The BCC demonstrated superior performance, achieving 96% degradation within 14 days, reducing the chemical oxygen demand of the PRE to 251 ± 27 mg L⁻¹ by the end of the treatment period, compared with A. calcoaceticus (85%), B. subtilis (90%), and P. putida (86%) over 21 days. At the completion of the 14-day cycle, the BCC decreased total dissolved solids to 173 ± 10 mg L⁻¹. Additionally, the BCC achieved 82% phenol removal within 14 days, surpassing the individual microbes requiring 21 days to reach equivalent remediation levels. Given the high initial phenolic load of the PRE (1382 ± 42 mg L⁻¹), these results demonstrate the strong capability of the BCC to effectively remove phenol and related phenolic compounds, leading to a substantial reduction in total phenolic content and enhanced effluent detoxification. Phytotoxicity assays confirmed that BCC treatment significantly reduced effluent toxicity, underscoring its potential as a rapid and effective method for PRE remediation. This study highlights the critical role of BCC in advancing sustainable solutions for industrial effluent treatment.