Cleaning efficiency and mechanism of ozone micro-nano-bubbles on ceramic membrane fouling

Membrane separation technology using ceramic membrane as carrier has attracted wide attention in drinking water treatment. However, the inevitable problem of irreversible contamination requires high intensity chemical cleaning in place (CIP) to ensure efficient ultrafiltration performance. Therefore, this study discussed the causes of membrane pollution, and further evaluated the purification effects of sodium hypochlorite, different aeration methods and different dosage of ozone as cleaning agents on membrane pollution. Comparison of the physicochemical properties and surface morphology of ceramic membranes before and after cleaning showed that ozone micro-nano-bubbles (O3-MNBs) had excellent cleaning efficiency at the same dosage. MNBs could provide shear forces, while their high mass transfer efficiency increased the dissolved ozone concentration rapidly. The degradation of fouling on the membrane surface was achieved by direct ozone oxidation and indirect oxidation by the generation of OH, resulting in a 100% flux recovery rate in a short time. Our results suggest that O3-MNBs, as a promising CIP method for ceramic membranes, not only significantly improves cleaning efficiency, but also reduces the negative environmental impact of chemical agents.