Effects of consecutive chemical cleaning on membrane performance and surface properties of microfiltration Original Research Article

Chemical cleaning is one of the main strategies to reduce membrane fouling. Effects of consecutive chemical cleaning on microfiltration were investigated with two feed waters; Feed 1 has a low turbidity of 12–55 NTU and Feed 2 has a high turbidity of 343–678 NTU. One cycle of the chemical cleaning was 1st alkaline wash with NaOH and NaOCl, acid wash with citric acid, and 2nd alkaline wash with NaOCl. The cleaning efficiency on flux recovery for experiments with both the two feed waters was decreased with increasing number of filtration cycle with periodic chemical cleaning although the reduced efficiency was substantial with Feed 2. According to membrane surface properties by atomic force microscopic images and roughness and contact angle measurement, the inadequate removal of organic foulant from membrane surface probably aggravated the flux decline with the membrane exposed to several cycles of filtration with the periodic chemical cleaning.