The role of EPS concentration on membrane fouling control: Comparison analysis of hybrid membrane bioreactor and conventional membrane bioreactor

A hybrid membrane bioreactor (HMBR) was developed by adding biofilm carriers into a conventional membrane bioreactor (CMBR), and comparison experiments were conducted to investigate the role of extracellular polymeric substances (EPS) on membrane fouling control in HMBR and CMBR for municipal wastewater treatment. Results showed that the concentrations of soluble EPS (S-EPS), loosely bond EPS (LB-EPS) and tightly bond EPS (TB-EPS) in the HMBR were decreased by 42.9%, 41.6% and 1.5%, respectively, compared with the CMBR. The physical properties of the activated sludge such as supernatant turbidity (ST), sludge volume index (SVI) and particle structure were found to be strongly influenced by LB-EPS concentration. In addition, major components of EPS could be detected as proteins, carbohydrates and humus, influence level of different components on sludge physical properties is polysaccharides > proteins > humus. After the same operational period, the cake layer resistance Rc and pore resistance Rp in the HMBR accounted for 43% and 56% of that in the CMBR, respectively. It resulted the duration of transmembrane pressure (TMP) to reach the prescribed maximum of 20 kPa from 57 days in the CMBR prolonged to 97 days in the HMBR. HMBR operation could control the LB-EPS concentration, and further controled the membrane fouling effectively.

► The role of EPS on membrane fouling control were investigated in HMBR and CMBR.
► The HMBR operation resulted in a 7.4% decrease of the total EPS concentration.
► Physical properties of the activated sludge were strongly influenced by LB-EPS.
► Decrease of the membrane resistance by the HMBR operation, eventually brought about a much slow increase of TMP.
► A linkage between EPS concentration, sludge property, and membrane fouling can be drawn.