Effect and mechanism of ultrafiltration membrane fouling removal by ozonation

This study is aimed using ozonation to remove the fouling that occurs on ultrafiltration membranes. Polyvinylidene fluoride (PVDF) was utilized for the membrane material. The tertiary effluent from industrial park wastewater plant was treated by an ultrafiltration membrane process. A bench-scale system was performed to evaluate the efficiency of fouling removed by an ozonation process. The results should be a valuable reference encouraging the recovery of tertiary effluent by the membrane process. The ozonation process was done via the direct continuous dosing of ozone into the influent. The ozone gas mass flow rate was 8.79 mg/min; the residual ozone concentration in the influent flow was maintained at about 4.02 mg/L throughout the test. It was demonstrated that without ozonation the permeate flux dropped to 60% after 1 h, but that with ozonation it could be maintained at 90% through the test. The SEM observations showed that much fouling that had clogged the membrane was effectively removed by ozonation. The mechanism of fouling removed was also illuminated by the IR analysis. It was observed that the ozone could oxidize and destroy the organic fouling, and the cross flow could flush away any loose fragments on the filtration cake.