Quorum quenching, biological characteristics, and microbial community dynamics as key factors for combating fouling of membrane bioreactors

Syed Salman Ali Shah,Kwang-Ho Choo,Luigi De Simone,Massimiliano Fabbricino,Kibaek Lee,Hyeona Park,Giuseppe Bruno,Irini Angelidaki

doi:10.1038/s41545-021-00110-9

Abstract

Membrane fouling is a major challenge in membrane bioreactors (MBRs) for wastewater treatment. This study investigates the effects of disturbance and solid retention time (SRT) on quorum-quenching (QQ) MBRs relative to antifouling efficacy and microbial community change. The fouling rate increases with the applied disturbance at a short SRT, counteracting the antifouling effect of QQ; however, it decreases with QQ at a long SRT. The microbial community appears to be responsible for such MBR behaviors. Several bacterial species belonging to the biofilm-forming group are dominant after disturbance, resulting in substantive membrane fouling. However, the balance between the bacterial species plays a key role in MBR fouling propensity when stabilized. Koflera flava becomes dominant with QQ, leading to reduced membrane fouling. QQ makes the MBR microbial community more diverse, while lowering its richness. QQ with long SRT would be a favorable operational strategy for effective MBR fouling control.

Highlights

Membrane fouling is the major technical challenge limiting the broader adoption of membrane bioreactors (MBRs) in wastewater treatment and reclamation[1,2,3]
Previous research reported that extracellular polymeric substances (EPSs) and soluble microbial products (SMPs) concentrations decreased with increased Solid retention time (SRT), alleviating fouling[8,9]
Two representative transmembrane pressure (TMP) profiles, the average fouling time, and the number of MBR runs at each phase are provided in Supplementary Fig. 1 and Supplementary Table 1

Summary

INTRODUCTION

Membrane fouling is the major technical challenge limiting the broader adoption of membrane bioreactors (MBRs) in wastewater treatment and reclamation[1,2,3]. SRT changes the microbial ecology of activated sludge in an MBR, influencing biofouling behaviors[11,12,13]. Biofouling control using indigenous QQ bacteria rather than QQ enzymes have been developed. Another study showed that SRT altered the abundance of bacterial groups due to QS and QQ activities in the MBR microbial community, which influenced the biofilm formation responsible for membrane biofouling[27]. Factors exposing stress to the microbiomes, such as shear forces, starvation conditions, dissolved oxygen (DO) content, and the presence of antibiotics, affect MBR membrane fouling by altering mixed liquor characteristics[28,29,30]. A stressful environment (starvation with high shear) was implemented in the middle of MBR operation while monitoring membrane fouling pattern and microbial community structure changes. We evaluated key MBR characteristics, such as biopolymer production, mixed liquor properties, and treatment efficiencies, and their correlations with MBR fouling rates

RESULTS AND DISCUSSION

METHODS

Analytical methods