Optimization of Magnetic Coagulation Process for River Water Treatment using the Response Surface Method

Response surface methodology (RSM) was applied to optimize the magnetic coagulation conditions for micro-polluted river water treatment. Based on single-factor experiment, Box-Behnken central composition experiment design was applied. The poly aluminum Chloride (PAC), magnetic particle, polyacrylamide (PAM), mixing stirring and flocculating stirring revolving speed were chosen as causal factors. RSM was employed to study the effects of these factors on the turbidity removal efficiency. Base on the target value (>95%), the results show that the optimum conditions were PAC 29.31 mgL(-1), magnetic particle 61.90mgL(-1), PAM 0.48mgL(-1), mixing stirring revolving speed 288rpm, flocculating stirring revolving speed 6 rpm. The average turbidity removal efficiency in three validation experiments was 95.36%, with the predicted value was 95.19%. The relative error between the measured data and the predicted value was 0.17%. It confirms that RSM was a useful tool to optimize the magnetic coagulation operating conditions for micro-polluted river water treatment.