Inactivation of bacteria present in secondary municipal wastewater effluent using the hybrid effect of Fe–TiO2 catalyst

Abstract

A low-cost waste-driven visible active iron-titanium oxide composite was fabricated for the treatment of real municipal wastewater. The structured composite was characterized using morphological and spectroscopic techniques such as FE-SEM, XRD, UV-DRS, indicating that the fabrication procedure could uniformly coat the TiO2 particles over the clay-supported composite spheres. The iron-titanium oxide composite was efficient in introducing a hybrid effect of photocatalysis and photo-Fenton that is being facilitated by the use of waste foundry sand (WFS) and waste fly ash (WFA) (both natural sources of iron) with a TiO2 layer on the outer surface. The main emphasis was given to the disinfection of bacteria along with the degradation of organic matter in terms of BOD and COD present in municipal wastewater. This hybrid technology showed 100% inactivation of bacteria with optimized parameters such as 0.9 g L−1 of H2O2 dose, 5.5 pH, and 100% surface area covered with the catalyst in 60 min of treatment time. 54% and 40% reduction in BOD and COD was also observed in 60 min. The kinetic rate constant was found to be 2 times higher in the hybrid process as compared to the individual process. The damage to the cell wall was confirmed by potassium ion leakage and FE-SEM analysis. Fe–TiO2 composites demonstrated excellent stability even after recycling 35 times, indicating the lasting durability of the composites. The findings of this study demonstrate the possibility for waste materials to be used as a viable approach for the bacterial inactivation application with the potential of the field-scale application.