Study on the nanofiltration membrane fouling control and cleaning efficiency of micro- and nanobubbles

To effectively prevent membrane fouling caused by inorganic scales, which block membrane pores during the nanofiltration process for direct drinking water treatment, the effects of micro/nanobubble introduction on membrane fouling control and membrane cleaning were studied during nanofiltration. The results showed that membrane flux increased 6.3% after micro- and nanobubbles were continuous introduced during the nanofiltration process. Micro- and nanobubbles effectively controlled membrane fouling and had less of an influence on the surface functional groups and polymer layers than did scale inhibitors. The membrane flux of the nanofiltration membrane after cleaning with micro- and nanobubbles decreased gradually with increasing cleaning time, and the membrane flux of the nanofiltration membrane after four rounds of cleaning decreased by 33%. Moreover, micro/nanobubble cleaning did not change the physical or chemical properties of the nanofiltration membrane and delayed the ageing rate of the nanofiltration membrane.