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Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
Achieving nitrogen removal via nitrite in a pilot-scale continuous pre-denitrification plant
Yong Ma1, Yongzhen Peng, Shuying Wang
1Key Laboratory of Beijing for Water Environment Recovery, Beijing University of Technology, Beijing 100022, China.
Water Research
|January 13, 2009
Summary
Achieving the nitrite pathway in wastewater treatment is possible by controlling dissolved oxygen. This method enhances nitrogen removal and reduces aeration costs, though it may affect sludge settleability.
Area of Science:
- Environmental Engineering
- Microbiology
- Wastewater Treatment
Background:
- Biological wastewater treatment plants with limited carbon benefit from nitrogen removal via the nitrite pathway.
- Achieving partial nitrification to nitrite in continuous domestic wastewater treatment processes is challenging.
Purpose of the Study:
- To demonstrate the reliable achievement of the nitrite pathway in a pilot-scale plant treating domestic wastewater.
- To evaluate the impact of the nitrite pathway on nitrogen removal efficiency and aeration costs.
- To investigate the microbial community shifts and operational challenges associated with the nitrite pathway.
Main Methods:
- Operating a pilot-scale continuous pre-denitrification plant (300 L) with controlled dissolved oxygen (DO) levels (0.4-0.7 mg/L).
- Utilizing Fluorescence In Situ Hybridization (FISH) analysis to monitor nitrite oxidizing bacteria (NOB) populations.
- Assessing total nitrogen (TN) removal, aeration costs, and sludge settleability (Sludge Volume Index).
Main Results:
- The nitrite pathway was reliably achieved, with over 95% of oxidized nitrogen as nitrite.
- Total nitrogen removal improved by approximately 20%, and aeration costs were reduced by 24%.
- Low DO levels led to a reduction in NOB populations, hypothesized to be due to washout, and a lag phase was observed for pathway establishment and upset.
Conclusions:
- Controlled low DO concentrations (0.4-0.7 mg/L) enable reliable nitrite pathway operation in domestic wastewater treatment.
- The nitrite pathway offers significant advantages in nitrogen removal and cost reduction but requires careful management due to potential impacts on sludge settleability.
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