Removal of natural organic matter (NOM) using ozonation and ultrafiltration

Pilot studies were conducted at Liu-Du water treatment located in Keelung, Taiwan. Raw water was first treated by conventional coagulation- sedimentation-filtration (CSF) processes, and then pumped into the pilot plants. For the pilot plants, both ozone/GAC and ozone/UF processes were operated simultaneously for NOM removal comparisons. Both systems were controlled at the same operating conditions with ozone dosing of 4.5, 6.0 and 9.0 mg/L. The results demonstrate that both ozone/UF and ozone/GAC processes can enhance NOM removal after the CSF process. More NOM was removed by the Ozone/GAC process because ozone broke the large molecules into smaller molecules, which increases the GAC adsorption potential. However, the ozone/UF process provides higher removal capacity in turbidity. In both processes, ozone dosing was not proportional to NOM removal of each process and 6.0 mg/L is found to be the optimal dosing. Owing to increasing adsorbability by ozonation, the ozone/GAC process is a very competitive process in NOM removal when associated with the CSF process.