Study and optimization of the UV/H2O2 process to treat contaminated wastewater coming from a pesticide formulation plant

Abstract

Abstract In the present work, the UV/H2O2 process was applied to evaluate the degradation of an industrial wastewater coming from a pesticide formulation plant. Commercial pesticides were added to reach an approximate initial value of Total Organic Carbon (TOC) and Carbon Oxygen Demand (COD) of 70 and 160 mg L− 1 respectively. Five pesticides were evaluated: atrazine, prometryn, imidacloprid, glyphosate and carbendazim. pH and R (ratio between initial H2O2 and initial TOC concentrations in mM) were varied in three levels: 3, 5.5, 8 and 2, 5, 8 respectively. TOC was measured as the response. The process was optimized employing the Response Surface Methodology (RSM). The obtained optimal conditions were: pH = 6.05 and R = 4.66 rendering a predicted TOC conversion of 74.70%. The experimental run under these conditions led to a TOC conversion of 78%. Glyphosate, atrazine and imidacloprid were completely removed while carbendazim was removed around 90% and prometryn at about 80%. Also, a significant decrease in COD was observed (around 82%) and the phytotoxicity assay showed that, at the end of the treatment, the sample was not phytotoxic. It can be concluded that the process can be satisfactorily modeled and optimized being efficient to treat this kind of wastewater.