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Updated: Jul 1, 2026
08:28
Creating Rapid Oxygen Oscillations in Microbial Single-cell Growth Analysis using a Microfluidic Double-layer Device
Published on: July 18, 2025
Dissolved oxygen as a key parameter to aerobic granule formation
B S McSwain Sturm1, R L Irvine
1Department of Civil, Environmental & Architectural Engineering, University of Kansas, Lawrence, KS 66045, USA. bmcswain@ku.edu
Summary
Dissolved oxygen and substrate removal kinetics are more critical for aerobic granular sludge formation in Sequencing Batch Reactors (SBRs) than high shear forces. Low dissolved oxygen levels prevent granule development, even with sufficient shear.
Area of Science:
- Environmental Science
- Biotechnology
- Wastewater Treatment
Background:
- Aerobic granular sludge formation in Sequencing Batch Reactors (SBRs) is often attributed to high shear forces.
- The distinct roles of shear force and dissolved oxygen in this process require further clarification.
Purpose of the Study:
- To differentiate the impact of shear force and dissolved oxygen on aerobic granular sludge development.
- To identify the primary factors governing granule formation in SBRs.
Main Methods:
- Two experiments were conducted using bench-scale SBRs.
- Experiment 1 varied superficial upflow gas velocities (shear force) while monitoring dissolved oxygen.
- Experiment 2 maintained constant shear force but varied dissolved oxygen concentrations.
Main Results:
- Aerobic granules disintegrated into flocs when shear force dropped below 1 cm s(-1), accompanied by increased SVI and effluent suspended solids.
- Dissolved oxygen levels below 5 mg L(-1) inhibited aerobic granule formation, irrespective of high shear force.
- Substrate removal kinetics and dissolved oxygen significantly influenced granule stability and formation.
Conclusions:
- Dissolved oxygen and substrate removal kinetics are more crucial for aerobic granular sludge formation than shear force.
- Optimal dissolved oxygen levels are essential for maintaining granule structure and function in SBRs.
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