[Modeling nitrogen transformation in a novel circular-flow corridor wetland]

Area of Science:

• Environmental Science
• Water Quality Management
• Ecological Engineering

Background:

• Nitrogen pollution poses a significant threat to aquatic ecosystems.
• Circular-flow corridor (CFC) wetlands offer a novel approach to wastewater treatment.
• Understanding nitrogen transformation pathways is crucial for optimizing wetland performance.

Purpose of the Study:

• To simulate and quantify nitrogen transformation and removal processes in a novel CFC wetland.
• To identify the primary mechanisms and pathways responsible for total nitrogen (TN) removal.
• To assess the impact of operational strategies on nitrogen removal efficiency.

Main Methods:

• Development of a computer model simulating 6 nitrogen forms, 3 media, and 10 transfer pathways.
• Analysis of seasonal variations in nitrogen removal pathways, particularly for ammonium-nitrogen (NH4(+)-N).
• Evaluation of the effects of plant harvesting, zeolite regeneration, and aquatic plant growth on TN removal.

Main Results:

• Zeolite adsorption (53.3%) and plant NH4(+)-N uptake (27.6%) were the dominant TN removal pathways.
• Seasonal variations were observed, with zeolite adsorption crucial in winter and plant uptake in spring.
• In summer, zeolite adsorption, nitrification, and plant uptake collectively contributed significantly to nitrogen removal.

Conclusions:

• CFC wetlands utilize diverse pathways for continuous nitrogen removal.
• Optimizing operational strategies like plant harvesting and zeolite regeneration can substantially enhance nitrogen removal rates.
• The study provides valuable insights for designing and managing effective wetland systems for nitrogen mitigation.