ABSTRACT
Membrane biofouling continues to limit the use of membrane bioreactor (MBR) for wastewater treatment. The conventional biofouling mitigation strategies have focused more on finding new membrane materials, and optimizing operational, chemical, and physical parameters. However, in recent years, there has been a shift in research focus toward biological approaches. The biological studies on membrane biofouling have resulted in an enhanced understanding of the composition of extracellular polymeric substances (EPS) and the role these play in biofilm formation on membrane surfaces. Another advance was the discovery of quorum sensing (QS) signal molecules and their role in EPS formation in MBR. Therefore, QS became a target in a quest for the sustainable biological solution to biofouling in MBR, leading to the discovery of another natural phenomenon to inhibit QS, called quorum quenching (QQ). Since 2009, QQ had been applied in laboratory scale MBRs in the form of free enzymes, immobilized enzymes, and entrapped QQ bacterial species. They all resulted in retarded membrane biofouling. Therefore, QQ bacterial species entrapped beads were introduced in pilot scale MBR in 2012 to bring it closer to practical application. Meanwhile, new QQ bacterial species have been isolated in an ongoing process to utilize QQ for biofouling control in MBR. QQ in MBR holds a promise for the future while more studies on the mechanism behind the process remain to be explored before it is commercialized as an effective way to deal with membrane biofouling.
