Effect of the addition of fine bubbles on reversible and irreversible membrane fouling in surface water treatment

Membrane processes have been used in numerous applications such as drinking water production from surface water. However, in the water treatment processes with membrane, a membrane fouling is a major problem. In this paper, we investigated the effect of microbubbles (MBs) and ultrafine bubbles (UFBs) on reversible and irreversible fouling in a river water treatment with ultrafiltration process to make a drinking water. The fouling was evaluated by fouling indexes. The relation between a fouling property and a content of dissolved organic matter was also discussed. As a result, it was found that the fouling was mainly a reversible fouling due to biopolymers in feedwater. It was also confirmed that MBs and UFBs prevented sedimentation of foulants on membrane surface for both irreversible and reversible foulings. MBs were more effective to reduce the fouling than UFBs.