Degradation of Carbaryl by Photolytic Ozonation

Abstract

The degradation of Carbaryl, a frequently used carbamate derivative pesticide, was carried out in batch reactors by photolytic ozonation. The influencing factors such as pH, pollutant concentration and ozone dosage were studied to optimize the reaction conditions. The maximum COD removal of 78.5% was achieved in three hours at alkaline pH 9. Increase in ozone dosage from 0.12 g/h to 0.48 g/h increased degradation rate. The apparent pseudo first order rate constant for photolytic ozonation and ozonation processes were found to be 0.0209 min $^{-1}$ and 0.0139 min $^{-1}$ respectively which indicated the presence of highly reactive hydroxyl radicals in photolytic ozonation. Complete mineralization needs longer ozonation time and only 48% TOC removal was achieved in three-hour duration. BOD5/COD ratio increased from 0.02 to 0.38 which facilitates coupling with secondary biological treatment.