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Mesocosm-Scale Constructed Wetland Design for Wastewater Treatment
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Enhanced nitrification-denitrification coupling for high-rate nitrogen removal in tidal flow constructed wetlands
Yuhuan Zou1, Jingjun Ruan1, Yongqiang Yang2
1State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
Bioresource Technology
|August 10, 2026
Summary
Optimizing tidal flow constructed wetlands (TFCWs) for nitrogen removal requires balancing nitrification and denitrification. This study enhanced nitrogen removal by managing substrate alkalinity, carbon availability, and hydraulic conditions, achieving over 80% total nitrogen removal.
Area of Science:
- Environmental Engineering
- Wastewater Treatment
- Wetland Systems
Background:
- Tidal flow constructed wetlands (TFCWs) face challenges in efficient nitrogen removal under high hydraulic loading rates (HLRs).
- Rapid water exchange in TFCWs can disrupt the nitrification-denitrification balance by altering oxygen and carbon availability.
- Optimizing TFCWs requires integrated strategies for substrate, carbon, and hydraulic management.
Purpose of the Study:
- To evaluate an integrated operational strategy for enhancing nitrogen removal in TFCWs under high HLRs.
- To investigate the effects of substrate alkalinity, carbon availability, and hydraulic conditions on nitrogen transformation processes.
- To understand the microbial community shifts in response to operational strategies.
Main Methods:
- Utilized TFCWs with an alkaline steel slag-zeolite substrate treating real domestic wastewater.
- Manipulated influent chemical oxygen demand to nitrogen (COD:N) ratios and employed methanol addition.
- Conducted vertical profiling and microbial community analyses (16S rRNA gene sequencing).
Main Results:
- The alkaline substrate maintained high ammonium-nitrogen removal (>93%) even at HLRs up to 2.51 m d⁻¹.
- Increasing the COD:N ratio to 8 significantly improved denitrification and total nitrogen removal (>80%).
- Carbon limitation was identified in deeper substrate layers, and methanol addition shifted microbial communities towards methylotrophic denitrifiers.
Conclusions:
- Coordinated regulation of substrate alkalinity, carbon availability, and hydraulic operation is crucial for efficient nitrification-denitrification coupling in TFCWs.
- The findings provide practical insights for optimizing TFCW design and operation for high-rate nitrogen removal.
- Understanding nitrogen transformation dynamics under high hydraulic loading is essential for effective wastewater treatment.
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