Photocatalytic Disinfection of Treated Wastewater Using Solar-Driven ZnO Nanoparticle Suspension Reactors

Abstract

The reuse of treated wastewater requires effective disinfection technologies capable of eliminating pathogenic microorganisms while minimizing chemical consumption and secondary pollution. This study investigates the photocatalytic disinfection of treated wastewater using solar-driven zinc oxide (ZnO) nanoparticle suspension reactors under varying environmental and operational conditions. The research focuses on evaluating microbial inactivation efficiency, photocatalytic activity, and reactor performance for sustainable wastewater disinfection applications. Experimental analyses were conducted to examine the influence of ZnO nanoparticle concentration, solar irradiation intensity, reaction time, pH, dissolved oxygen level, and initial microbial load on disinfection efficiency and photocatalytic reaction behavior. Results demonstrated that solar-activated ZnO nanoparticles effectively generated reactive oxygen species capable of damaging microbial cell membranes, proteins, and nucleic acids, leading to significant reduction of pathogenic microorganisms in treated wastewater. The suspension reactor system provided enhanced catalyst dispersion and improved light penetration, contributing to efficient photocatalytic activity and rapid microbial inactivation. Optimized operating conditions substantially improved disinfection performance while minimizing catalyst dosage and treatment time. Kinetic evaluation revealed that photocatalytic inactivation follows reaction pathways strongly influenced by solar intensity and catalyst surface interactions. The study further indicated that solar-driven photocatalysis offers environmental and economic advantages through renewable energy utilization and reduced dependence on conventional chemical disinfectants. Comparative assessment with traditional disinfection methods confirmed the effectiveness of ZnO nanoparticle suspension reactors in achieving high microbial removal efficiency with lower formation of harmful disinfection by-products. The findings highlight the potential of solar photocatalytic technology as an efficient and sustainable approach for wastewater reuse and advanced water treatment applications.