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Updated: May 24, 2026
06:10
Extraction of Structural Extracellular Polymeric Substances from Aerobic Granular Sludge
Published on: September 26, 2016
Improved phosphate removal by selective sludge discharge in aerobic granular sludge reactors
J P Bassin1, M-K H Winkler, R Kleerebezem
1Department of Biotechnology, Delft University of Technology, Julianalaan 67, Delft 2628 BC, The Netherlands.
Biotechnology and Bioengineering
|February 15, 2012
Summary
Selective sludge removal from aerobic granular reactors significantly improves phosphorus removal at higher temperatures. Discharging biomass primarily from the top of the sludge bed favors polyphosphate-accumulating organisms (PAOs) over glycogen-accumulating organisms (GAOs), boosting efficiency.
Area of Science:
- Environmental Science
- Microbiology
- Wastewater Treatment Engineering
Background:
- Aerobic granular sludge sequencing batch reactors (SBRs) are used for wastewater treatment.
- Phosphorus (P) removal efficiency in SBRs can be temperature-dependent.
- Microbial community composition, specifically the balance between polyphosphate-accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs), influences P removal.
Purpose of the Study:
- To compare P removal efficiency and microbial community composition in aerobic granular SBRs at 20°C and 30°C.
- To investigate the effect of selective sludge discharge strategies on P removal at elevated temperatures.
- To optimize conditions for favoring PAOs over GAOs to enhance P removal.
Main Methods:
- Operation of two lab-scale aerobic granular SBRs at 20°C and 30°C.
- Control of sludge retention time (SRT) using different sludge discharge strategies (uniform vs. selective top-biased removal).
- Analysis of microbial community composition using fluorescent in situ hybridization (FISH).
Main Results:
- P removal efficiency was higher at 20°C (>90%) than at 30°C (60%) with uniform sludge removal.
- Selective sludge removal (80% top, 20% bottom) at 30°C resulted in 100% P removal efficiency.
- Selective removal at 30°C led to a shift in microbial community, with PAOs dominating and the formation of white, high-ash granules.
Conclusions:
- Sludge discharge strategy is critical for maintaining high P removal efficiency, especially at elevated temperatures.
- Selective discharge of biomass from the top of the sludge bed effectively favors PAOs over GAOs.
- Optimizing SRT control through selective sludge removal is a viable method to enhance biological phosphorus removal in aerobic granular SBRs.
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