Investigation of nitrogen removal effect and greenhouse gas emission of Fe-C-based tidal flow constructed wetlands

LI Dapeng; LIU Songqi; SONG Xinyu

doi:10.13205/j.hjgc.202509003

Volume 43 Issue 9

Sep. 2025

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LI Dapeng, LIU Songqi, SONG Xinyu. Investigation of nitrogen removal effect and greenhouse gas emission of Fe-C-based tidal flow constructed wetlands[J]. ENVIRONMENTAL ENGINEERING , 2025, 43(9): 20-28. doi: 10.13205/j.hjgc.202509003

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LI Dapeng, LIU Songqi, SONG Xinyu. Investigation of nitrogen removal effect and greenhouse gas emission of Fe-C-based tidal flow constructed wetlands[J]. ENVIRONMENTAL ENGINEERING , 2025, 43(9): 20-28. doi: 10.13205/j.hjgc.202509003

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Investigation of nitrogen removal effect and greenhouse gas emission of Fe-C-based tidal flow constructed wetlands

doi: 10.13205/j.hjgc.202509003

1. School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China

Received Date: 2025-06-05
Available Online: 2025-11-05
Publish Date: 2025-09-01

Abstract

Abstract

Due to the insufficiency of available carbon sources and dissolved oxygen （DO） in the effluent， as well as the low temperature， the total nitrogen （TN） removal efficiency of traditional constructed wetlands is relatively low， accompanied by the release of considerable amounts of greenhouse gases （N₂O， CO_2， and CH₄）. It has been shown that the TN removal rate of traditional CW is less than 50%， and with the continuous operation of the CW system， clogging problems will occur. In addition， the low temperature inhibits the activity of microorganisms， which in turn affects the normal play of their purification efficiency， resulting in a nitrogen removal efficiency of 30% below. In this study， biochar and pyrite were used as the substrates to investigate the nitrogen removal performance and greenhouse gas emissions of ordinary gravel and iron-carbon based constructed wetlands under tidal flow operation for the treatment of low carbon-to-nitrogen ratio （C/N） effluent from municipal wastewater treatment plants. The influence of temperature on the nitrogen removal performance of iron-carbon based constructed wetlands was further explored. The results showed that TN removal rates of iron-carbon based constructed wetlands at 10 ℃ and 25 ℃ were 13.07% and 17.32% higher than those of the ordinary gravel constructed wetlands， respectively. Prolonging the hydraulic retention time （HRT） could further enhance the nitrogen removal efficiency， and the greenhouse effect produced was not significantly higher than that of ordinary gravel constructed wetlands. Temperature changes did not affect the removal of ammonia nitrogen （NH₄⁺-N） in municipal effluent by tidal flow constructed wetlands， but low temperature was unfavorable for the removal of nitrate nitrogen （NO₃^--N）， resulting in a low TN removal efficiency. The abundance of nitrification functional gene amoA and denitrification functional gene nosZ， as well as the activities of ammonia monooxygenase （AMO） and nitrous oxide reductase （NOS） in the iron-carbon based constructed wetland system， were significantly affected by temperature and HRT， which were the key factors influencing the TN removal efficiency in the wetland system.
- tidal flow constructed wetland,
- greenhouse gas,
- pyrite,
- biochar,
- tailwater deep nitrogen removal

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References

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