Coupled cavitation and AOPs treatment of Primene-JMT containing wastewater

Abstract

The application of various cavitational reactors as the novel approach to remove the emerging contaminant, Primene-JMT (PJMT), in an aqueous solution has been elucidated in this work. Ultrasonic step horn (US step horn), longitudinal horn based ultrasound (LHUS), hydrodynamic cavitation (HC) with single slit venturi (HCSV), and dual slit venturi (HCDV) are the specific reactors studied individually and in combination with Advanced Oxidation Processes (AOPs) involving H2O2, Fenton, O3, and NaClO. Different operating parameters such as oxidant loadings, oxidant ratios, treatment time, and the inlet pressure have been varied to elucidate the optimum conditions. The optimal conditions established in the study are H2O2 dosing of 0.8 g/L, H2O2/Fe2+ ratio of 4/1, O3 flow rate of 3LPH, and NaClO dosing of 0.8 g/L as applicable for the specific process. The US+NaClO and US+Fenton+CaO schemes were shown to be most effective at laboratory scale in achieving a maximum COD reduction of 98 % each at pH of 9 after 120 min and 130 min, respectively. Under the optimum conditions, LHUS+NaClO and HCDV+NaClO schemes were also successfully applied on pilot scale, showing the maximum COD reductions of 90 % and 96 % and cavitational yield of 0.89×10−3mg/J and 26.34×10−3mg/J, respectively. Comparison of different cavitating devices revealed that a dual slit venturi was nearly 30 % more efficient than a single slit venturi under similar conditions. It was clearly demonstrated that a combination strategy under optimum conditions was advantageous for attaining the highest COD reduction and cavitational yield at the lower operational cost.