Advanced nitrogen and phosphorus removal by combining endogenous denitrification and denitrifying dephosphatation in constructed wetlands

Hu Wu; Jie Wang; Jieyu Chen; Xiaoning Wang; Dapeng Li; Jie Hou; Xugang He

doi:10.1016/j.jenvman.2021.112967

Advanced nitrogen and phosphorus removal by combining endogenous denitrification and denitrifying dephosphatation in constructed wetlands

J Environ Manage. 2021 Sep 15:294:112967. doi: 10.1016/j.jenvman.2021.112967. Epub 2021 Jun 9.

Authors

Hu Wu¹, Jie Wang¹, Jieyu Chen¹, Xiaoning Wang¹, Dapeng Li², Jie Hou³, Xugang He⁴

Affiliations

¹ College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China.
² College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan, 430070, China; Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, 430070, China.
³ College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan, 430070, China; Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, 430070, China. Electronic address: shengwuhj@mail.hzau.edu.cn.
⁴ College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan, 430070, China; Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, 430070, China. Electronic address: xgh@mail.hzau.edu.cn.

PMID: 34116311
DOI: 10.1016/j.jenvman.2021.112967

Abstract

To achieve high-efficiency nutrient removal in constructed wetlands (CWs), a novel simultaneous nitrogen and phosphorus removal (SNPR) process was developed by combining nitrification, endogenous denitrification, and denitrifying phosphorus removal. In SNPR process, denitrifying glycogen-accumulating organisms (DGAOs) and denitrifying polyphosphate-accumulating organisms (DPAOs) utilized NO_x^--N(NO₃^--N or NO₂^--N) as electron acceptor and poly-beta-hydroxy-alkanoates (PHAs) as carbon sources for endogenous denitrification and denitrifying phosphorus removal processes. Results from 217 days of operation showed that a high-level of nitrogen removal efficiency of 83.73% was achieved with influent COD/N of 4. The success was attributed to the fact that most of influent carbon sources could be transformed into PHAs before nitrification via enriching DGAOs and DPAOs in CW, which simultaneously improved nitrification and denitrification due to reducing oxygen and carbon sources consumption by aerobic heterotrophs. Phosphorus was mainly removed via denitrifying phosphorus removal, and PO₄^3--P removal efficiency reached up to 87.84% with even common gravel used as substrate. Stoichiometry analysis revealed that DGAOs were the main organisms providing nitrite to DPAOs, suggesting that the effective PO₄^3--P removal under high DGAO abundance condition might be attributed to the coordination of DGAOs and DPAOs in SNRP processes.

Keywords: Constructed wetlands; Denitrifying phosphorus removal; Endogenous denitrification; Simultaneous nitrogen and phosphorus removal.

MeSH terms

Bioreactors
Denitrification
Nitrogen*
Phosphorus*
Sewage
Waste Disposal, Fluid
Wetlands

Substances

Sewage
Phosphorus
Nitrogen