Optimization of coagulation–flocculation process in the treatment of surface water for a maximum dissolved organic matter removal using RSM approach

Abstract The aim of this research work is the optimization of the coagulation/flocculation process in the treatment of surface water for maximum dissolved organic matter (DOM) removal using response surface methodology (RSM). For this purpose, several jar test experiments were performed in order to identify the most influencing factors. Afterwards, RSM was done to investigate the effects and the interactions of three chosen variables (coagulant concentration, flocculant concentration, and initial pH), whereas the responses were the DOM removal in terms of chemical oxygen demand (COD), in terms of absorbance at the wavelength 254 nm (UV-254), and the final pH. The optimal conditions were as follows: 133 mg/L of coagulant, 60 mg/L of flocculant and an initial pH equal to 6.91. Under these conditions, the efficiency removals were 56% in terms of COD and 59% in terms of UV-254 with a final pH equal to 6.78. High variance coefficient R2 values, with 0.96 for the removal in terms of COD and 0.92 in terms of UV-254, confirm the reliability and the validity of the obtained model.