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The Benthic Exchange of O2, N2 and Dissolved Nutrients Using Small Core Incubations
Published on: August 3, 2016
Long-term effect of dissolved oxygen on partial nitrification performance and microbial community structure.
Jianhua Guo1, Yongzhen Peng, Shuying Wang
1School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China. jianhuaguo316@yahoo.com.cn
Bioresource Technology
|February 10, 2009
Summary
Low dissolved oxygen (DO) in sequencing batch reactors (SBRs) enhances simultaneous nitrification and denitrification (SND) by over 44%, optimizing sludge properties and achieving over 95% partial nitrification via nitrite.
Area of Science:
- Environmental biotechnology
- Wastewater treatment
- Microbial ecology
Background:
- Partial nitrification via nitrite is a key step in advanced biological nitrogen removal.
- Dissolved oxygen (DO) levels significantly influence nitrification and denitrification processes.
- Understanding microbial community structure is crucial for optimizing wastewater treatment.
Purpose of the Study:
- To investigate and compare the performance of partial nitrification via nitrite in two sequencing batch reactors (SBRs) with different DO levels.
- To analyze the microbial community structure under varying DO conditions.
- To evaluate the efficiency of simultaneous nitrification and denitrification (SND) and sludge properties.
Main Methods:
- Two SBRs were operated with distinct DO levels: high DO (above 3 mg/l) and low DO (0.4-0.8 mg/l).
- Real-time aeration duration control was employed to achieve stable partial nitrification.
- Fluorescence in situ hybridization (FISH) and scanning electron microscopy (SEM) were used to analyze microbial communities and sludge morphology.
Main Results:
- Both reactors achieved stable partial nitrification with a nitrite accumulation ratio exceeding 95%.
- Low DO SBR demonstrated significantly higher SND efficiency (44.9%) and specific SND rates (0.83 mg N/(mg MLSS h)) compared to the high DO reactor (7.7% and 0.20 mg N/(mg MLSS h)).
- Low DO conditions resulted in lower effluent turbidity and did not negatively impact sludge settling properties; dominant ammonia-oxidizing bacteria (AOB) were observed in both reactors, with nitrite-oxidizing bacteria (NOB) not detected.
Conclusions:
- Optimizing DO levels and employing process control methods are crucial for achieving efficient biological nitrogen removal via partial nitrification and SND.
- Low DO conditions favor SND and sludge optimization without compromising effluent quality.
- Ammonia-oxidizing bacteria (AOB) dominate under these conditions, suggesting a robust pathway for nitrogen removal.
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