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Selection pressure-driven aerobic granulation in a sequencing batch reactor
1Division of Environmental and Water Resources Engineering, School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. cyliu@ntu.edu.sg
Applied Microbiology and Biotechnology
|April 1, 2005
Summary
Aerobic granulation, forming in sequencing batch reactors (SBRs), is driven by selection pressures like settling time and exchange ratio. Adjusting these factors controls granule formation and characteristics.
Area of Science:
- Environmental microbiology
- Biotechnology
- Wastewater treatment
Background:
- Aerobic granulation is crucial for efficient wastewater treatment.
- Formation of aerobic granules primarily occurs in sequencing batch reactors (SBRs).
- The underlying reasons for SBR-specific granulation remain unclear.
Purpose of the Study:
- To review factors influencing aerobic granulation in SBRs.
- To identify key selection pressures driving aerobic granule formation.
- To propose a unifying concept for understanding granulation mechanisms.
Main Methods:
- Literature review of factors affecting aerobic granulation.
- Analysis of substrate composition, organic loading, hydrodynamics, and operational parameters.
- Introduction and quantitative demonstration of the minimal settling velocity concept.
Main Results:
- Identified settling time and exchange ratio as major selection pressures.
- Proposed a minimal settling velocity concept to unify observed effects.
- Demonstrated that granulation can be manipulated by adjusting settling time and exchange ratio.
Conclusions:
- Aerobic granulation is a cell-to-cell immobilization process driven by selection pressures.
- The minimal settling velocity concept provides a framework for understanding granulation.
- SBR operational parameters, specifically settling time and exchange ratio, are key to controlling aerobic granulation.