Response surface analysis of toluene biodegradation in wastewater using sand soil biofilm systems

This study investigates the optimization of biological treatment for toluene-contaminated wastewater using biofilms developed in sand soil media. Pseudomonas aeruginosa was cultivated on fine and coarse sand media in Perspex column reactors to evaluate the effects of contact time, biomass dosage, liquid flow rate, and initial toluene concentration on % removal efficiency. Response Surface Methodology (RSM) was employed to model and optimize the process parameters, identifying significant interactions between variables. Fine sand media outperformed coarse sand, achieving higher removal efficiency due to increased surface area, improved biofilm adhesion, and extended contact time. ANOVA results confirmed the model's robustness, with contact time and initial toluene concentration emerging as critical factors. The optimization revealed maximum removal efficiency (87.1 %) under optimal conditions: 189.4 h of contact time, 170.664 mg L −1 biomass dosage, 0.303 L min −1 liquid flow rate, and 538.25 mg L −1 initial toluene concentration. These findings highlight the potential of biofilm-based treatment systems for industrial wastewater, offering an eco-friendly and cost-effective solution. The study underscores the importance of integrating RSM in designing efficient and scalable wastewater treatment processes.