Abstract:
A variety of physical, chemical and biological methods have been adapted for control of biofouling in membrane bioreactors which is considered a major limiting factor in adaptation of MBRs at large scale. This study investigated a variety of biofouling control methods i.e. relaxation, permeate backwashing, chemical enhanced backwashing and Quorum Quenching. MBRs with different biofouling control strategies were operated and their effect on biofouling retardation, change in sludge characteristics and removal efficiency of organics and nutrients in wastewater were compared. Combined quorum quenching (QQ) and chemical enhanced backwashing (CEB) strategy resulted in 3.7 times longer filtration cycle in MBR as compared with that of permeate backwashing (PBW) but QQ+CEB strategy negatively affected the sludge characteristics. In comparison, QQ+PBW approach was found to reveal better sludge characteristics in terms of Extracellular Polymeric Substance (EPS) and capillary suction time (CST) while exhibiting slight difference in biofouling control. COD and NH4+-N removal efficiencies were found to be reduced from 93 to 79% and from 64 to 38%, respectively in MBRs having CEB using NaOCl concentration of 3.5 mg/L.
