Optimizing enhanced coagulation for DOC removal with ultrafiltration membrane separation using response surface methods and particle trajectory analysis

An enhanced coagulation study was conducted on bench scale to determine the optimal coagulation condition in terms of pH and coagulant dose for DOC removal by response surface method. 2² factorial design was performed to obtain the optimal coagulation condition of pH = 6.0 and alum dose = 50.4mg/l. A membrane separation experiment with ultrafiltration unit was conducted with the selected conditions of pH and alum dose around the optimal coagulation condition. Flux change, DOC removal efficiency, and turbidity removal efficiency were measured to see the performance of membrane separation. The particle trajectory model suggested by Altena and Belfort was used to analyze the relationship between the size of particles formed by enhanced coagulation and the fouling of ultrafiltration membrane processes, with simulation of the experimental conditions used in this study. The flux of PM30 ultrafiltration membrane was strongly affected by particle size formed in coagulation pretreatment rather than DOC removal rate.