Photocatalytic oxidation process (UV/H2O2/ZnO) in the treatment and sterilization of dairy wastewater

Abstract

Advanced Oxidation Processes (AOP) have attracted much interest of scientific and industrial communities. Therefore, this process was employed experimentally to determine its efficacy in treating dairy effluents. For this, it was employed an artificial light reactor using photolysis (UV), hydrogen peroxide (H2O2) as an oxidant, and zinc oxide (ZnO) as an alternative catalyst. The variables studied in the photocatalysis were: H2O2, ZnO, under different values of pH, both in relation to the interferences with the reaction rate and with the process efficiency. First order differential equations were applied in determining the degradation rate over the hydraulic retention time (HRT); the F-test and the signal: noise ratio comparison were used to test the significance of variables. The AOP using photolysis UV, H2O2 and ZnO was effective in COD removal with 80% efficiency. As for the sterilization, in terms of total and fecal coliforms the efficiency was 100%, with the most probable number of total and fecal coliforms (MPN 100 mL-1) equal to zero. A catalyst/oxidant/pH ratio was observed at 1 g 30 mL-1 4-1 for a better kinetic-chemical reaction, for 1 hour lighting.