Optimizing coagulation-flocculation processes with aluminium coagulation using response surface methods

A data-based multivariate method such as response surface methods and desirability function is considered advantageous for analysing coagulation treatment optimization. Thus, this study investigated the optimization of coagulation-flocculation using response surface methodology. The parameters investigated were pH, alum dose and alkalinity. The optimum coagulation conditions for the individual responses: turbidity, colour, residual aluminium and phenanthrene were pH 7.0, alum dose 80.0 mg/L and alkalinity 80.0 mg/L; pH, 6.5, alum dose 70.0 mg/L and alkalinity 90.0 mg/L; pH, 7.0, alum dose 63.2 mg/L and alkalinity 80.0 mg/L and pH 6.2, alum dose 80.0 mg/L and alkalinity of 80.0 mg/L, respectively. The model equation derived from the optimization study was adequate for predicting the response values. The quadratic model was significant (p < 0.0001), and it had a high correlation (R2, 0.746-0.975) and an insignificant (LOF, p > 0.05) lack of fit.