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A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities
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Published on: December 25, 2015

Microbial behaviors involved in cake fouling in membrane bioreactors under different solids retention times

Bing Wu1, Shan Yi, Anthony G Fane

  • 1Singapore Membrane Technology Centre, Nanyang Technological University, Singapore, Singapore. wubing@ntu.edu.sg

Bioresource Technology
|December 3, 2010
PubMed

Insights

Longer sludge retention times (SRTs) in membrane bioreactors (MBRs) increase cake-fouling due to smaller flocs and more extracellular polymeric substances (EPS). Microbial community shifts also impact EPS production and membrane performance.

Area of Science:

  • Environmental Engineering
  • Biotechnology
  • Water Treatment

Background:

  • Membrane bioreactors (MBRs) are effective wastewater treatment systems.
  • Membrane fouling remains a significant challenge in MBR operations.
  • Sludge retention time (SRT) is a critical operational parameter influencing MBR performance.

Purpose of the Study:

  • To investigate the impact of different sludge retention times (SRTs) on biomass characteristics and membrane performance in MBRs.
  • To understand the relationship between activated sludge properties, microbial community structure, and membrane fouling.
  • To identify factors contributing to cake-fouling and biofouling propensity.

Main Methods:

  • Operation of MBRs at a high flux (30 L/m² h) with varying SRTs (10, 30 days, and infinity).
  • Monitoring of biomass characteristics (floc size, EPS content, MLSS concentration).
  • Analysis of microbial community shifts using DGGE (Denaturing Gradient Gel Electrophoresis).
  • Assessment of membrane performance and cake-fouling development.

Main Results:

  • The MBR operated at an infinite SRT exhibited more severe cake-fouling.
  • This fouling correlated with smaller activated sludge floc size and increased extracellular polymeric substances (EPS) amount.
  • DGGE analysis revealed distinct microbial community shifts across different SRTs, influencing EPS production.
  • Diverse microbial communities developed on membrane surfaces under various SRTs and operating stages.

Conclusions:

  • Activated sludge characteristics (MLSS, EPS properties) and hydrodynamics, influenced by SRTs, are linked to cake layer development and membrane fouling.
  • Understanding EPS characteristics and bacterial floc deposition is crucial for developing effective biofouling control strategies in MBRs.
  • Optimizing SRT is essential for mitigating membrane fouling and ensuring efficient MBR operation.

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