Periodic fouling control strategies in gravity-driven membrane bioreactors (GD-MBRs): Impact on treatment performance and membrane fouling properties

Abstract
This study aims to assess the effects of periodic membrane fouling control strategies in Gravity-Driven Membrane Bioreactor (GD-MBR) treating primary wastewater. The impact of each control strategy on the reactor performance (permeate flux and water quality), biomass morphology, and fouling composition were evaluated. The application of air scouring coupled with intermittent filtration resulted in the highest permeate flux (4 LMH) compared to only intermittent filtration (i.e., relaxation) (1 LMH) and air scouring under continuous filtration (2.5 LMH). Air scouring coupled with relaxation led to a thin (~50 μm) but with more porous fouling layer and low hydraulic resistance, presenting the lowest concentration of extracellular polymeric substance (EPS) in the biomass. Air scouring under continuous filtration led to a thin (~50 μm), dense, compact, and less porous fouling layer with the highest specific hydraulic resistance. The employment of only relaxation led to the highest fouling formation (~280 μm) on the membrane surface. The highest TN removal (~62%) was achieved in the reactor with only relaxation (no aeration) due to the anoxic condition in the filtration tank, while the highest COD removal (~ 60%) was achieved with air scouring under continuous filtration due to the longer aeration time and the denser fouling layer. The results highlighted the importance of performing in-depth fouling characterization to link the membrane fouling properties to the hydraulic resistance and membrane bioreactor performances (i.e., water quality and water production). Moreover, this work proven the versatility of the GD-MBR, where the choice of the appropriate operation and fouling control strategy relies on the eventual discharge or reuse of the treated effluent.

Citation
Ranieri, L., Johannes, S., Vrouwenvelder, & Fortunato, L. (2022). Periodic fouling control strategies in gravity-driven membrane bioreactors (GD-MBRs): Impact on treatment performance and membrane fouling properties. Science of The Total Environment, 156340. https://doi.org/10.1016/j.scitotenv.2022.156340

Acknowledgements
The research reported in this paper was supported by funding from King Abdullah University of Science and Technology (KAUST), Saudi Arabia. Authors extend their gratitude to the Water Desalination and Reuse Center (WDRC) staff for their support. The authors would like to highlight the contribution of Xavier Pita, Scientific Illustrator at the King Abdullah University of Science and Technology (KAUST) for production of the Fig. 4.

Publisher
Elsevier BV

Journal
The Science of the total environment

DOI
10.1016/j.scitotenv.2022.156340

PubMed ID
35654208

Additional Links
https://linkinghub.elsevier.com/retrieve/pii/S0048969722034374

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