Exploring the mechanism of membrane fouling alleviation with furanone and its derivatives addition as quorum sensing inhibitors

Membrane fouling is still the primary bottleneck issue for the widespread application of anaerobic membrane bioreactor (AnMBR) and quorum quenching (QQ) strategy is one of the feasible approaches for its fouling alleviation. In this study, 2(5H)-furanone was applied as an efficient, cost-effective and non-toxic QSI in a laboratory-scale AnMBR, achieving not only a doubled membrane filtration cycle length but also ensuring relatively stable treatment performance and enhanced methane production. The retarded membrane fouling could result from reduced soluble microbial product (SMP) and extracellular polymer substance (EPS) concentration, decreased by 13.6 % and 26.8 % compared with that in conventional AnMBR. Meanwhile, the biocake morphology also suggest reduced biofilm thickness and less organic deposition on the QQ-AnMBR. The microbial diversity analyses indicated that 2(5H)-furanone addition can accumulate the fermentative and acetogenic bacteria (Propioniciclava, Longilinea and norank_f__Anaerolineaceae in both sludge mix suspensions and biocake) and methanogens (Methanosaeta in bulk sludge, Methanosaeta and Methanobacterium in the biocakes), improving the anaerobic process in AnMBR. Moreover, the relative abundance of norank_f__norank_o__SJA-15, a typical filamentous bacterium and fouling-related microbe, significantly reduced after 2(5H)-furanone addition in the bulk sludge of QQ-AnMBR. Additionally, this study elucidated the membrane fouling control mechanism by 2(5H)-furanone addition through metagenomic and molecular docking analyses. Results indicate that 2(5H)-furanone may control membrane fouling mainly through quorum sensing processes inhibition by (i) competition of 2(5H)-furanone and acyl-homoserine lactones (AHLs) for binding sites on QS receptor proteins, and (ii) quorum quenching with increased lactone enzymes abundance and decreased AHLs concentration. These findings offer valuable insights that can significantly contribute to the advancement of this technology with membrane fouling control.