Fouling and Cleaning of Reverse Osmosis Membranes duing Municipal Tap Water Treatment on A Pilot-Scale Plant

Xianhui Li, Danyan Yan, Genghong An, Dawei Jing , Jianxin Li



This study in situ investigated the membrane performance of reverse osmosis (RO) elements along longitudinal direction in a pilot-scale plant with six CSM-2540 RO elements during municipal tap water treatment at the constant recovery and flux. The continuous chemical cleaning processes were carried out with hydrochloric acid cleaning, sodium hydroxide cleaning and hydrochloric acid cleaning. The membrane performance was in situ monitored by the system and element pressure drop and the rejection of organic and inorganic foulants. According to this study, the tail-elements were easily suffered more serious fouling than the other in the RO system. The pressure drop at back-end unit was larger than that at the other as a result of high osmotic pressure and concentration polarization, especially at the end of fouling operation. In the whole RO system, the rejection of cations was higher than the anions of the same valence at initial operation and close to that of anions at the later stage of fouling experiment. Further, it was found that the organic foulant mainly deposited on the lead-elements, and the inorganic salt mainly precipitated on the tail-elements. Moreover, the performance of fouled membranes was restored by using the conventional acid-base cleaning protocol.


Keywords: Reverse osmosis, Membrane fouling, Pilot-scale system, Water treatment, Acid-base cleaning