Operating conditions on the optimization and water quality analysis on the advanced treatment of papermaking wastewater by coagulation/Fenton process

A coagulation/Fenton process was used for the advanced treatment of papermaking wastewater. Optimal reaction conditions were proposed based on the removal efficiency and the operating costs. The overall removal efficiency of chemical oxygen demand (COD) reached 86.5% for polyaluminium chloride and polyacrylamide concentrations of 120 and 1mg/L, H2O2 dosage of 4mmol/L, and [H2O2]/[Fe2+] molar ratio of 1. The distribution and transformation of the polarity and molecular weight of the organic matter in raw wastewater, in the coagulation process effluent, and in the Fenton process effluent were also studied. The coagulation process efficiently removed the hydrophobic fraction, which comprised 60% of the fractions in the raw wastewater. The decrease in COD during the coagulation process reduced the required H2O2 dosage in the subsequent Fenton process. The cost of the coagulation/Fenton process amounted to 0.78 RMB/m(3), which was lower than that of the classic Fenton process alone (1.39 RMB/m(3)). Thus, this study offered an efficient and cost-effective method for the advanced treatment of papermaking wastewater.