Combined treatment processes based on ultrasound and photocatalysis for treatment of pesticide containing wastewater #29

Abstract

The research area of water purification/wastewater treatment has been extensively growing in the last few decades, especially as the water quality control and regulations against hazardous pollutants are becoming more stringent. Wastewater generated from the pesticide and chemical industries contains toxic and nonbiodegradable compounds, and it is imperative to develop efficient treatment approaches. A promising way to achieve/enhance the degradation of biologically and chemically stable molecules like pesticides is by the application of advanced oxidation processes (AOPs). The chapter focuses on the application of sonochemical reactors and photocatalytic oxidation reactors, either operated individually or in combination, for the treatment of pesticide-containing wastewaters. Initially introduction to the sonochemical reactors has been presented along with the discussion about the benefits that can be obtained using different combinations of advanced oxidation processes based on the sonochemical reactors, Fenton’s chemistry, ozonation, and use of hydrogen peroxide. Guidelines have been presented for the selection of optimum parameters for maximizing the process intensification benefits. Overview of earlier literature in the specific area of sonophotocatalytic oxidation has also been presented. In the last part of chapter, a case study related to the degradation of dichlorvos pesticide in aqueous solution using ultrasonic cavitation and photocatalytic oxidation has been discussed to highlight the methodology for optimization and the expected benefits that can be obtained using the combination approach. Overall it appears that using a combination of advanced oxidation processes under optimized conditions yields significant benefits as compared to the individual operations.