Evaluation of color and COD removal by Fenton from biologically (SBR) pre-treated pulp and paper wastewater

Abstract

Abstract Pulp and paper industry has generated a higher contamination burden of the final mill wastewater which must be further treated to comply with the standards imposed by the legislation requirement. In this study, the removal efficiencies for chemical oxygen demand (COD) and color from pulp and paper wastewater using sequencing batch reactor (SBR) in combination with advanced oxidation processes (AOPs) at a bench scale were investigated. Response surface methodology (RSM) based on a three-variable-three-level central composite design (CCD) was employed to optimize the SBR process. At the optimal conditions of initial COD of 1000 mg/L, MLSS of 3000 mg/L and cycle time of 24 h, 74.8% COD, 58.3% of color removal and 80 mL/g of SVI were obtained in the pretreatment stage. The use of Fenton oxidation as post-treatment enhanced COD reduction and color removal. A percentage of 92.1% COD reduction and 90.3% of color removal was achieved in dosages of 3 mM Fe2+ and 9 mM H2O2 at pH of 3.0 for a reaction time of 30 min, while a total of 98% reduction of COD and 94% removal of color for the combined treatment was achieved.