ReviewMembrane fouling control in membrane bioreactors (MBRs) using granular materials

•The use of granular materials to control membrane fouling in MBRs was reviewed.•Adsorbents adsorb SMPs and improve sludge characteristics, hence fouling mitigation.•Granular media extends filtration period, increases flux (20-30%), and reduces aeration by 50%.•Granular sludge enhances membrane permeability, extends filtration period, and improves flux.•Quorum quenching-entrapped media mitigate biofouling (∼27-40% energy savings).

Membrane fouling is considered the major limitation of membrane bioreactors (MBRs). This paper provides an overview on fouling mitigation in MBRs using granular materials. Adsorbents addition extends filtration period, improves critical flux as well as sludge properties (increased flocs size, reduced soluble EPS, improved dewaterability). However, determination of optimal dosages of adsorbents is needed to balance cost savings from fouling mitigation versus cost of adsorbents and sludge handling. The abrasion from granular media reduces cake layer formation, extends membrane filtration period, increases flux (∼20-30%), and reduces aeration intensity by 50%. Finding appropriate aeration intensity and optimum dose for different media is critical for full-scale application. Granular sludge substantially reduces fouling in MBRs; but, optimal operational conditions for long-term granule stability are required. Quorum quenching (QQ) mitigates biofouling (energy savings ∼27-40%). Cost savings from QQ need assessment against the production and application of QQ approaches.