Modeling nitrogen removal in a constructed wetland treatment system

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Wastewater Management

Background:

• Constructed wetland treatment systems (CWTS) are utilized for wastewater nitrogen removal.
• Previous CWTS design relied on empirical methods and basic kinetic models, which are often system-specific.
• There is a need to explore advanced kinetic models for improved CWTS design and performance.

Purpose of the Study:

• To develop and validate advanced lumped and distributed parameter models for nitrogen transformations in CWTS.
• To assess the applicability of various reaction kinetic models for simulating nitrogen removal processes.
• To quantify the relative contributions of different processes (e.g., denitrification, plant uptake, nitrification) to overall nitrogen removal.

Main Methods:

• Development of lumped and distributed parameter models incorporating diverse reaction kinetics.
• Integration of nitrogen transformation processes within the distributed parameter model.
• Verification and application of developed models using laboratory and pilot-scale experimental data.
• Estimation of reaction rate parameters via non-linear least square analysis.

Main Results:

• CWTS conditions were accurately simulated using a plug flow model.
• Plant uptake was identified as a more significant process than denitrification for nitrate removal.
• Nitrification and plant uptake demonstrated equal dominance in ammonia nitrogen removal.
• The distributed parameter model successfully elucidated the contributions of various processes to nitrogen removal.

Conclusions:

• The developed simulation model provides a robust tool for CWTS planning and design.
• This model aids in the effective control and treatment of nitrogen pollution in wastewater.
• Advanced kinetic modeling enhances the understanding and optimization of CWTS performance.