Degradation kinetics of pollutants present in a simulated wastewater matrix using UV/TiO2 photocatalysis and its microbiological toxicity assessment

Water pollution is one of the major concerns over long-term sustainability of the environment. Effective and efficient treatment of polluted wastewater is still a serious challenge for global researchers. In the last 2-3 decades, due to the incessant emergence of micropollutants in surface and ground water bodies, several endeavors have been made to resolve the water pollution issues either through chemical, physical and biological degradation processes or through removal/separation processes using different adsorbents and membranes. It has been found that most of the studies are mainly limited to single or binary pollutant analysis in a pure water matrix. Therefore, in this novel investigation, a mixture of five different pollutants has been studied for UV/TiO2-based photocatalytic degradation. In the present study, a commercially available TiO2, an antibiotic, i.e. Ciprofloxacin and four different synthetic dyes, i.e. Rhodamine B, Methylene Blue, Methyl Orange and Amaranth have been used as a photocatalyst, a pharmaceutical and various industrial dyes, respectively, in a batch photocatalytic reactor system with a stirrer. It is important to note that the commercial TiO2 photocatalyst has also been characterized with the help of several characterization techniques. The present study is mainly focused on the degradation of different micropollutants present in the simulated wastewater matrix and their individual degradation kinetics. It is interesting to observe that MB and RhB have shown the maximum degradation followed by CIP (96.21, 96.15 and 89.62%, respectively). In addition, a microbiological assay has also been performed to check the toxicity variation in the degraded products. It is quite interesting to observe that the simulated wastewater matrix has completely lost its microbial toxicity within 120 min of UV/TiO2-based photocatalytic treatment. Finally, total organic carbon evaluations of various treated samples have also been performed and the obtained results substantiate the theory of assimilable organic carbon.