Optimization of photochemical decomposition of aniline in aqueous solutions and assessment of effluent toxicity using Pseudomonas aeruginosa ATCC 27853.

Aniline is a toxic chemical compound that poses serious risks to human health. Its introduction into aquatic environments can threaten the health of humans and other living organisms. This study aimed to investigate the removal of aniline from aqueous solutions using the TiO₂/H₂O₂/UV photocatalytic process and to evaluate the toxicity of the treated effluent. Experiments were conducted under controlled laboratory conditions using a photocatalytic batch reactor with an approximate volume of three liters. To investigate the effects of pH, TiO₂ nanoparticle concentration, initial concentration, and contact time on aniline removal efficiency, a Central Composite Design (CCD) was employed. Data analysis was carried out using Design Expert software, version 13. In addition, the toxicity of the effluent was assessed using the Alamar Blue (AB) reduction assay, which is based on the metabolic activity of Pseudomonas aeruginosa. The results of this study showed that the maximum aniline removal efficiency under optimized conditions reached 98%. Furthermore, the toxicity of the treated effluent was assessed using a novel evaluation method based on the AB assay and the metabolic activity of P. aeruginosa. Based on this assessment, the EC₅₀ value was determined to be 1.64 mg/L. A significant correlation was observed between the reduction of AB dye and the viability of P. aeruginosa, confirming the reliability of this method for post-treatment toxicity monitoring. The findings of this study demonstrated that the photocatalytic process exhibited a reasonable efficiency in degrading aniline and was, also, capable of reducing the biological toxicity of the treated effluent. Accordingly, when combined with the novel toxicity assessment method introduced in this study, this process may be considered a viable option for enhancing advanced industrial wastewater treatment.