Nitrogen transformations in a wetland receiving lagoon effluent: sequential model and implications for water reuse

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Ecological Engineering

Background:

• Constructed wetlands offer low-tech solutions for wastewater treatment and reuse, particularly in arid environments.
• Effective nitrogen removal is crucial for wetland functionality and effluent quality.
• Existing designs require refinement for optimal nitrogen management.

Purpose of the Study:

• To develop and validate a sequential model for nitrogen transformations in constructed wetlands.
• To identify strategies for improving nitrogen removal efficiencies in arid region wetlands.
• To assess the impact of environmental factors on nitrogen removal processes.

Main Methods:

• Calibrated and verified a sequential model simulating nitrogen transformations (organic N to ammonium, ammonium to nitrate, nitrate to nitrogen gas).
• Utilized data from a constructed wetland in Kingman, Arizona.
• Ran model scenarios to evaluate the effects of varying nitrification and denitrification rates.

Main Results:

• The sequential model successfully predicted nitrogen species in the influent and effluent.
• Optimizing summer nitrification and winter denitrification rates significantly improves nitrogen removal.
• Evidence indicates that winter denitrification may be limited by available carbon.

Conclusions:

• A sequential nitrogen transformation model is effective for predicting wetland performance.
• Enhancing winter carbon supply, possibly through dryland vegetation, could improve denitrification.
• Model-based adjustments can optimize constructed wetland design for nitrogen removal in arid regions.