Using TiO2-Diatomite for photodisinfection in contaminated wastewater

Abstract

INTRODUCTION: The urban pressure reduced water availability and quality through the years, promoting the development of water treatment and disinfection processes such as the Advanced Oxidation Process (AOP). A highly efficient catalyst with Diatomite as biotemplate and solar energy can enhance hydroxyl radicals (OH) production for disinfection and pollutants degradation. Preliminary TiO2-Diatomite experiments with Escherichia coli provided valuable insights on its photodisinfection efficiency, legitimating its usage in the wastewater samples presented in this study. OBJECTIVES: Evaluate the use of TiO2-Diatomite in photodisinfection process in contaminated wastewater. MATERIALS AND METHODS: TiO2 synthesis used titanium isopropoxide sol-gel process with Diatomite powder, the filtration step followed the mixed water suspension, and the drying process lasted overnight. The wastewater samples were collected from a household washing machine and 0.05 g of TiO2-Diatomite were added in the photodisinfection reactor. The total reaction lasted for 90 minutes in the solar chamber with all parameters controlled. The suspension aliquots were collected after 30 minutes of agitation and plated on LB agar at Petri plates. After incubation, the emerged colonies were counted through software (OpenCFU) and the data processed using R programming language. DISCUSSION AND RESULTS: The Scanning Electron Microscopy (SEM) micrograph of TiO2-Diatomite presented enhanced surface area and microstructure obtained by biotemplate addition. The bacterial inactivation percentage was above 75 % for 1 hour of solar radiation exposure. Kinetics models indicated better correspondence with interparticle reaction. CONCLUSION: Photodisinfection kinetics studies provided more efficient bacterial inactivation with the addition of 0.05 g of TiO2-Diatomite in the sample. The study presents an affordable and sustainable treatment using a viable renewable energy source for application in distant areas with contaminated effluents with the addition of a reagent easily obtained by government agencies.