Combined advanced oxidation and biological treatment processes for the removal of pesticides from aqueous solutions

Advanced oxidation processes were combined with biological treatment processes in this study to remove both pesticides and then the COD load from aqueous solutions. It was found that O3 and O3/UV oxidation systems were able to reach 90 and 100%, removal of the pesticide Deltamethrin, respectively, in a period of 210 min. The use of O3 combined with UV radiation enhances pesticides degradation and the residual pesticide reaches zero in the case of Deltamethrin. The combined O3/UV system can reduce COD up to 20% if the pH of the solution is above 4. Both pesticide degradation and COD removal in the combined O3/UV system follow the pseudo-first-order kinetics and the parameters of this model were evaluated. The application of the biological treatment to remove the bulk COD from different types of feed solution was investigated. More than 95% COD removal was achieved when treated wastewater by the O3/UV system was fed to the bioreactor. The parameters of the proposed Grau model were estimated.