Determination of operational conditions for tertiary treatment of slaughterhouse wastewater by the integrated Fenton-Coagulation process

Abstract

Advanced oxidation processes (AOPs) appear to be effective methods for tertiary wastewater treatment because they are able to destroy pollutants and not only transfer them from one phase to another without destroying them as is the case with conventional tertiary processes applied in the slaughterhouse industries. Biological processes are the main slaughterhouse wastewater treatments applied, but this process is limited to the degradation of biodegradable substances which are not toxic to the biological culture. The Fenton Coagulation integrated process may be a promising alternative for slaughterhouse tertiary treatment. This study evaluated the operational conditions for the proposed integrated process application to slaughterhouse wastewater tertiary treatment. Investigated parameters were [Fe+2]/[H2O2] ratio and pHCOAGULATION. The experiments were conducted in triplicate according to the rotational central composite design (RCCD) 22, with three center points and four axial points, totaling 11 experiments. Chemical oxygen demand (COD) removal was the parameter used to evaluate efficiency in each assay. The operational conditions defined in the range investigated were [Fe+2]/[H2O2] ratio equal to 0.800 and pHCOAGULATION of 5.50. The study revealed that the proposed Fenton-Coagulation process performed within the defined conditions promoted a COD removal efficiency of 71% and, thus, may be used to degrade recalcitrant (non-biodegradable) organic matter during slaughterhouse wastewater tertiary treatment.