Fouling Control, Using Various Cleaning Methods, Applied on an MBR System Through Continuous TMP Monitoring

Membrane fouling is the major disadvantage of MBRs, which leads to decreased membrane performance and increased operating expenses. In this study, fouling was monitored in a pilot-scale submerged MBR system fed with municipal wastewater and operated under intermittently aerated conditions. Transmembrane pressure (TMP) was measured online on the membrane module during the whole operating period; permeability and resistance were estimated on a daily basis as well. The most common fouling prevention processes were systematically assessed and optimized. To control TMP increase owing to biosolids accumulation on membrane surface, successive backflushing cycles, backwash volume increase, air-cross flow velocity increase and in/ex situ mechanical cleaning were applied. Hydraulic cleaning resulted in TMP improvement and flux recovery of 40% and 32%, respectively. Ex situ and in situ mechanical cleaning led to TMP improvement of 25% and 39%, corresponding to flux recovery of 63% and 189%, respectively. Increased aeration intensity improved TMP and increased permeate flux by 63% and 56%, respectively. In the case of fouling that was caused by pore blocking and cake layer formation, chemical cleaning was implemented on the membrane module. Extensive chemical cleaning with NaOCl solution led to permeate flux increase of 90%, corresponding to TMP improvement of 44%.