Examination of oxygen release from plants in constructed wetlands in different stages of wetland plant life cycle

Zhang, Jian; Wu, Haiming; Hu, Zhen; Liang, Shuang; Fan, Jinlin

Examination of oxygen release from plants in constructed wetlands in different stages of wetland plant life cycle

2014

Zhang, Jian | Wu, Haiming | Hu, Zhen | Liang, Shuang | Fan, Jinlin

The quantification of oxygen release by plants in different stages of wetland plant life cycle was made in this study. Results obtained from 1 year measurement in subsurface wetland microcosms demonstrated that oxygen release from Phragmites australis varied from 108.89 to 404.44 mg O₂/m²/d during the different periods from budding to dormancy. Plant species, substrate types, and culture solutions had a significant effect on the capacity of oxygen release of wetland plants. Oxygen supply by wetland plants was estimated to potentially support a removal of 300.37 mg COD/m²/d or 55.87 mg NH₄-N/m²/d. According to oxygen balance analysis, oxygen release by plants could provide 0.43–1.12 % of biochemical oxygen demand in typical subsurface-flow constructed wetlands (CWs). This demonstrates that oxygen release of plants may be a potential source for pollutants removal especially in low-loaded CWs. The results make it possible to quantify the role of plants in wastewater purification.

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