Effects of ozonation on removal of turbidity in drinking water using ceramic membrane ultrafiltration

Abstract

The effect of ozone on the performance of a hybrid ozone-ceramic membrane ultrafiltration was investigated using raw water with different turbidities. Average pore size of ceramic membrane tested was 100 nm. Ozonation with 3 mg·L-1 ozone increased the membrane fluxes by 18.2%~104.9% with raw water turbidities ranging from 14 to 510 NTU. The percentages increased to 21.7%~116.3% for 5 mg·L-1 ozone. There was no significant effect on the membrane flux for the ozone dosage of 1 to 2 mg·L-1. Ozonation with 5 mg·L-1 dosage removed 28.7%~46.9% organics in terms of CODMn. While 1~3 mg·L-1 ozone did not remove CODMn significantly, its concentrations increased slightly in membrane effluent. Ozonation converted the organics into smaller molecular weight, which decreased the membrane fouling, and improved the membrane flux. The 2~3 μm particle counts in the effluent of the hybrid process were 10~36 cnt·mL-1. Ozonation may result in slight increase of particle count in the membrane effluent. Exploration of particulate matter breaking through membrane pore in this paper is of practical importance for the improvement of particle removal in membrane ultrafiltration.