Sustainable Degradation of Organophosphate Contaminated Wastewater By Hydrodynamic Cavitation: A New Insight Into Synergistic Ways of Integration of AOPs and Their Effects, Kinetics and Energy-Economics

Abstract

The impact of advanced oxidation processes (AOPs) integration with hydrodynamic cavitation (HC) along with energy-economics, has been studied towards the sustainable degradation of the organophosphate (OP) pesticide-contaminated agrochemical wastewater. Initially, the geometric interpretations of HC have been studied by hydrodynamic analysis towards selection of an optimal orifice device. The independent and integrated effects of AOPs were investigated for degradation. The optimal operational parameters for HC along with the degradation kinetics have been established. The reduction in total organic carbon (TOC) obtained by different approaches for 240 minutes of treatment time is reported. Treatment with HC alone resulted in 71% reduction, HC + H₂O₂ achieved 82%, HC + O₃ reached 79%, HC + H₂O₂ + O₃ resulted in 80% reduction. Among all combinations, based on energy-economics and kinetic-studies, the case of ozonation(O₃) given as pretreatment to HC has shown the highest degradation with 95% TOC reduction. In comparison to the simultaneous integration of O₃ with HC, the operational time required for TOC reduction of 90% was found to be 1.24 times lower with ozone pretreatment followed by HC operation, moreover the cost of operation drastically reduced by 14-fold. The byproduct analysis also shows that independent O₃ treatment for degradation, leads to the formation of secondary contaminants. However, the standalone HC process is found to be the most cost-effective, with 21-fold lesser operational costs as compared to the integrated processes but has a higher operational time. Therefore, the integrated process of O₃ pretreatment + HC was found to be a promising technology for OP degradation in terms of operational time and costs, while not generating any byproducts.