Optimization of Aeration Strategies in Sequencing Batch Reactors for Improved BOD and COD Removal

Application of Moving Bed Biofilm Reactors (MBBR) for Secondary WasteWater Treatment under Low Temperature Conditions

1. Introduction

Sequencing batch reactors (SBR) are widely used in secondary Wastewater Treatment due to their operational flexibility and ability to handle variable influent loads. Aeration strategy is a critical factor affecting biological activity, oxygen transfer efficiency, and overall pollutant removal. In conventional SBR operation, continuous aeration may lead to excessive energy consumption and suboptimal removal of BOD and COD. This study evaluates alternative aeration strategies, including intermittent and phased aeration, to improve treatment efficiency while reducing energy costs.

2. Materials and Methods

Pilot-scale SBR systems were set up with influent characteristics representative of municipal secondary effluent. Aeration strategies tested included continuous aeration, intermittent aeration with 30-minute cycles, and phased aeration targeting high-load periods. Sludge retention times were maintained at 10–15 days. Parameters monitored included dissolved oxygen, BOD₅, COD, ammonia, and microbial activity indicators. Energy consumption was recorded for each aeration strategy to assess operational efficiency. Statistical analyses were applied to compare treatment performance across different aeration modes.

3. Results

Intermittent and phased aeration strategies demonstrated significant improvements in BOD and COD removal compared to continuous aeration. BOD removal efficiency increased from 85% under continuous aeration to over 92% with optimized intermittent aeration, while COD removal reached 90–95%. Ammonium removal also improved under intermittent aeration due to enhanced nitrification and denitrification cycles. Energy consumption decreased by approximately 20% in intermittent aeration systems, demonstrating both environmental and economic benefits. Microbial analysis indicated more diverse and active microbial communities under intermittent aeration, contributing to improved substrate degradation and process stability.

4. Discussion

Optimized aeration strategies in SBR systems enhance pollutant removal efficiency while reducing energy requirements. Intermittent aeration creates alternating aerobic and anoxic conditions, promoting simultaneous organic matter degradation and nitrogen transformation. Phased aeration aligns oxygen supply with peak influent loads, avoiding unnecessary aeration during low-load periods. The study emphasizes the importance of balancing treatment performance with operational cost, highlighting that targeted aeration strategies can significantly improve both BOD and COD removal in secondary wastewater treatment.

5. Conclusion

Optimizing aeration in SBR systems is an effective approach to enhance BOD and COD removal, improve microbial community activity, and reduce energy consumption. Intermittent and phased aeration strategies provide significant advantages over continuous aeration, making SBRs more sustainable and efficient for secondary wastewater treatment. These findings offer practical guidance for wastewater treatment facilities aiming to maximize performance while minimizing operational costs.