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Updated: Aug 11, 2026
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A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities
Published on: December 25, 2015
Membrane bioreactor versus conventional activated sludge system: population dynamics of nitrifiers
R Manser1, W Gujer, H Siegrist
1Swiss Federal Institute for Environmental Science and Technology and Swiss Federal Institute of Technology, CH-8600 Dübendorf, Switzerland. reto.manser@eawag.ch
Summary
Membrane bioreactors (MBRs) and conventional activated sludge systems show similar microbial communities and nitrification performance. Membrane separation does not significantly alter nitrifying bacteria composition or overall nitrification rates.
Area of Science:
- Environmental Microbiology
- Water Treatment Engineering
- Biotechnology
Background:
- Membrane bioreactors (MBRs) are increasingly used for wastewater treatment.
- Limited research exists on how membrane separation impacts microbial communities in MBRs.
- Understanding these impacts is crucial for optimizing MBR performance.
Purpose of the Study:
- To compare the startup and operational performance of an MBR with a conventional activated sludge (CAS) system.
- To investigate the influence of membrane separation on the nitrifying microbial community composition.
- To assess the nitrification performance in both systems over an eight-month period.
Main Methods:
- Parallel operation of MBR and CAS pilot plants treating domestic wastewater.
- Controlled operation at identical sludge ages.
- Fluorescent in situ hybridization (FISH) for nitrifying bacteria identification.
- Confocal laser scanning microscopy (CLSM) for microbial aggregate analysis.
Main Results:
- Minor differences observed in ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) communities between MBR and CAS.
- Both systems demonstrated comparable maximum nitrification rates.
- CLSM revealed nitrifying bacteria aggregates within flocs, overgrown by heterotrophic bacteria.
Conclusions:
- Membrane separation in MBRs does not significantly affect nitrifying community composition.
- Nitrification performance remains largely unaffected by the membrane separation process itself.
- Potential impacts on kinetic parameters warrant further investigation.
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