Integrated biological and UV-Fenton processes for the treatment of automobile service station wastewater

Automobile service stations are a significant contributor to environmental issues due to the release of harmful wastewater containing various pollutants like oils, grease, detergents, and organic and inorganic substances. Our study focused on treating this wastewater through both biological and UV-Fenton methods to target the removal of chemical oxygen demand (COD), turbidity, and oil and grease for potential reuse. In the biological approach, we isolated diverse microorganisms from the wastewater, and the predominant microorganism identified through 16S rRNA sequencing was <i>Pseudomonas aeruginosa</i>. Key parameters, including pH (6.2) and incubation time (45.6 h), were optimized using response surface methodology (RSM) to enhance pollutant degradation. The microorganisms were immobilized on biofilm carriers, achieving significant reductions: 83% COD, 93% turbidity, and 67% oil and grease. For the second method, we employed a UV-Fenton-based advanced oxidation process, optimizing Fe²⁺ dosage (42.4 mg/L) and H₂O₂ concentration (412.1 mg/L). This process demonstrated substantial reductions: 89% COD, 95% turbidity, and 72% oil and grease. Combining both biological and UV-Fenton treatments in series yielded even better outcomes with reductions of 89% COD, 96% turbidity, and 78% oil and grease. This integrated approach proved highly effective in meeting wastewater quality standards, demonstrating significant pollutant reduction within acceptable limits.