Application of an innovative front aeration and internal recirculation strategy to improve the removal of pollutants in subsurface flow constructed wetlands

Chien Jung Lin; Jih Ming Chyan; Wen Xue Zhuang; Floradelle Aboga Vega; Rose Marie O Mendoza; Delia B Senoro; Ruei Feng Shiu; Chih Hsiang Liao; Da Ji Huang

doi:10.1016/j.jenvman.2019.109873

Application of an innovative front aeration and internal recirculation strategy to improve the removal of pollutants in subsurface flow constructed wetlands

J Environ Manage. 2020 Feb 15:256:109873. doi: 10.1016/j.jenvman.2019.109873. Epub 2019 Dec 9.

Authors

Chien Jung Lin¹, Jih Ming Chyan², Wen Xue Zhuang³, Floradelle Aboga Vega⁴, Rose Marie O Mendoza⁵, Delia B Senoro⁶, Ruei Feng Shiu⁷, Chih Hsiang Liao⁸, Da Ji Huang⁹

Affiliations

¹ Department of Environmental Resources Management, Chia Nan University of Pharmacy and Science, Tainan, 71710, Taiwan, ROC. Electronic address: cjlin@mail.cnu.edu.tw.
² Department of Environmental Resources Management, Chia Nan University of Pharmacy and Science, Tainan, 71710, Taiwan, ROC. Electronic address: mjmchyan@mail.cnu.edu.tw.
³ Department of Environmental Resources Management, Chia Nan University of Pharmacy and Science, Tainan, 71710, Taiwan, ROC. Electronic address: love83720@gmail.com.
⁴ Camarines Norte State College, Daet 4600 Camarines Norte, Philippines; Graduate School of Engineering, Adamson University, Ermita 1000, Manila, Philippines. Electronic address: efav_2012@yahoo.com.ph.
⁵ Department of Environmental Science and Engineering, Adamson University, Ermita 1000, Manila, Philippines. Electronic address: rosemarie.mendoza@adamson.edu.ph.
⁶ Civil Engineering and Environmental Engineering, Mapua University, Manila, 1101, Philippines. Electronic address: dbsenoro@mapua.edu.ph.
⁷ Bioengineering, University of California, Merced, CA, USA. Electronic address: rueifeng.shiu@gmail.com.
⁸ Department of Environmental Resources Management, Chia Nan University of Pharmacy and Science, Tainan, 71710, Taiwan, ROC. Electronic address: chliao@mail.cnu.edu.tw.
⁹ Department of Environmental Resources Management, Chia Nan University of Pharmacy and Science, Tainan, 71710, Taiwan, ROC. Electronic address: daji@ms19.hinet.net.

PMID: 31822455
DOI: 10.1016/j.jenvman.2019.109873

Abstract

The pollutant removal performance of traditional horizontal subsurface flow (HSSF) constructed wetlands (CWs) is limited because of the dissolved oxygen (DO) supply is insufficient. The aeration of HSSF CWs usually improves their pollutant removal performance, but a high DO induces the accumulation of nitrate-nitrogen (NO₃^--N) and suppresses the improvement of total nitrogen (TN) removal. In this study, an integrated solution that involved in-tank front aeration and internal recirculation (FAIR) was used to improve the pollutant removal performance of HSSF CWs. Based on the experimental results, the FAIR system significantly increased the removal efficiencies of biochemical oxygen demand (BOD) from 53.8-76.0% to 82.0-91.7% and reduced the BOD concentration in the effluent to below 10 mg L^-1. The removal efficiency of ammonia-nitrogen (NH₃-N) increased from 15.1-78.3% to 98.5-98.6% while the removal efficiencies of the total Kjeldahl nitrogen (TKN) of the control and FAIR HSSF CWs were 18.2-77.1% and 93.5-94.3%, respectively. HSSF CWs with FAIR outperformed aerated HSSF CWs in the removal of NH₃-N and TKN. The effects of two recirculation flow ratios (Rr = recirculation flow rate/influent flow rate), 14.3 and 3.0, on the improvement of pollutant removal performance were investigated. The lower Rr did not significantly affect the improvement of BOD, NH₃-N, and TKN, but a higher Rr resulted in more severe accumulation of NO₃^--N. The removal efficiency of TN in control HSSF CWs ranged from 20.4% to 75.5%, and in the FAIR HSSF CW was 71.6% for Rr = 14.3 and 81.3% for Rr = 3.0. However, the FAIR system did not enhance the removal performance of total phosphorus, suggesting that the DO level and internal recirculation were not dominant mechanisms for the removal of phosphorous. The easy maintenance of the FAIR system made it a superior modification for improving the pollutant removal performance of HSSF CWs.

Keywords: Ammonia-nitrogen; Biochemical oxygen demand; Constructed wetlands; Front aeration; Internal recirculation; Total nitrogen.

MeSH terms

Ammonia
Environmental Pollutants*
Nitrogen
Phosphorus
Waste Disposal, Fluid
Wetlands*

Substances

Environmental Pollutants
Phosphorus
Ammonia
Nitrogen