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Updated: Dec 25, 2025
A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities
Published on: December 25, 2015
Rapid aerobic sludge granulation in an integrated oxidation ditch with two-zone clarifiers
1College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China; College of Geomatics and Municipal Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310018, China.
A novel method rapidly cultivated aerobic granular sludge (AGS) using external sludge treatment and two-zone clarifiers. This approach enhances sludge settleability and pollutant removal efficiency for wastewater treatment.
Area of Science:
- Environmental Science
- Microbiology
- Chemical Engineering
Background:
- Conventional wastewater treatment often struggles with low-strength domestic sewage.
- Developing efficient methods for aerobic granular sludge (AGS) formation is crucial for improving wastewater treatment processes.
- Understanding the mechanisms driving AGS granulation is key to optimizing treatment performance.
Purpose of the Study:
- To rapidly cultivate aerobic granular sludge (AGS) in an integrated oxidation ditch system.
- To investigate a novel external sludge treatment and return mode for enhanced granulation.
- To evaluate the impact of this method on sludge characteristics, microbial community, and pollutant removal efficiency.
Main Methods:
- Utilized an integrated oxidation ditch with two-zone clarifiers for selective sludge retention.
- Implemented an external sludge conditioning process involving CaCl2 and air drying to promote extracellular polymeric substances (EPS) secretion.
- Returned conditioned surplus sludge to the reactor to facilitate granulation via hydraulic shear forces.
Main Results:
- Successfully formed AGS within 18 days of operation.
- Achieved stable mixed liquor suspended solids (MLSS) of ~3500 mg/L and sludge volume index (SVI5) of ~40.0 mL/g after 51 days.
- Observed significant improvements in biological sludge activity, EPS content, and microbial community structure, with enrichment of EPS-secreting and granule-stabilizing microbes.
- Demonstrated enhanced pollutant removal efficiency and reduced energy consumption.
Conclusions:
- The novel external sludge treatment and return mode effectively promotes rapid AGS formation and improves wastewater treatment performance.
- The two-zone clarifier design plays a critical role in selective sludge retention, driving granulation.
- The method is energy-efficient and eco-friendly, showing strong potential for full-scale application in domestic sewage treatment.
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