Effect of pre-ozonation on filtration of micro-polluted drinking water using ceramic membranes with different pore sizes

Abstract

The influence of pre-ozonation on the performance of ceramic membranes was investigated with an ozone-ceramic membrane hybrid testing system. Three ceramic membranes with different pore size were tested with raw water polluted by organic matter. The membrane flux, particulate matter and organic matter were used to evaluate the performance of ceramic membranes. Pre-ozonation led to the increase in flux of ceramic membrane related to the control. Compared with the membrane filtration alone, the fluxes in the hybrid process were improved by 34.2%-38.8%, 29.2%-56.4% and 7.2%-12.2% for 200, 100 and 10 nm ceramic membrane, respectively. It was found that the hybrid process can effectively remove particulate matter. More than 99% of turbidity was removed and the 2-3 μm particle count in permeate was less than 60, 40 and 30 cnt/mL for 200, 100 and 10 nm ceramic membrance. Membrane filtration alone resulted in a reduction of 15.1%-30.8% in the CODMn concentration. About 11.0%-16.7% increase in removal percentage was found for 10 nm ceramic membrane after pre-ozonation. However, pre-ozonation caused a slight increase in the concentration of CODMn in the effluent of 100 and 200 nm ceramic membrane after pre-ozonation with the ozone dosage of less than 3 mg/L. About 10% of UV254 can be removed by the single membrane filtration and it can be improved to 12.0%-49.9% in the hybrid process. The removal of UV254 was mainly attributed to the pre-ozonation.