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Updated: May 29, 2026
08:05
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
Nitrate reduction in a simulated free-water surface wetland system
Teresa M Misiti1, Malek G Hajaya, Spyros G Pavlostathis
1School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA.
Water Research
|September 3, 2011
Summary
Constructed wetlands effectively treat nitrate-contaminated groundwater from biosolids, achieving over 90% nitrogen removal. Optimal performance requires a 3-day hydraulic retention time and sufficient carbon, even at low temperatures (5°C).
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
- Wastewater Management
Background:
- Land application of biosolids can lead to nitrate contamination of groundwater.
- Ammonia released from biosolids degrades, forming nitrates (65-400 mg N/L) in aquifers.
Purpose of the Study:
- Investigate the feasibility of constructed wetlands for treating nitrate-contaminated groundwater.
- Determine the impact of temperature, hydraulic retention time (HRT), and carbon loading on denitrification.
Main Methods:
- Laboratory-scale constructed wetland system using site-specific soil and groundwater.
- Batch assays to measure maximum specific reduction rates (MSRR) for nitrate and nitrite.
- Continuous-flow reactors and model simulations to assess wetland performance.
Main Results:
- Nitrate reduction rate was independent of initial nitrate concentration.
- Maximum specific reduction rates (MSRR) at 22°C were 1.2 ± 0.2 mg N/mg VSS(COD)-day for nitrate and 0.7 ± 0.1 mg N/mg VSS(COD)-day for nitrite.
- Temperature coefficient for nitrate reduction was estimated at 1.13.
Conclusions:
- Constructed wetlands can achieve >90% nitrogen removal efficiency.
- Effective treatment is possible with HRT ≥ 3 days and temperatures as low as 5°C, provided sufficient biodegradable carbon is available.
- Constructed wetlands are a viable solution for treating nitrate-contaminated groundwater in the southeastern US.
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