Performance of woody and herbaceous plant polyculture in constructed wetland for treating domestic wastewater

Abstract

Effect of polyculture of woody and herbaceous plant with different ecological niche in constructed wetlands (CWs) on wastewater treatment is unclear. Herein, three kinds of polyculture CWs were constructed to treat domestic wastewater: woody polyculture system (W, Nerium and Hibiscus), herbaceous polyculture system (H, Acorus and Typha), woody and herbaceous polyculture system (WH, Nerium, Hibiscus, Acorus and Typha) and non-planted system (N) as control. The seasonality removal performance of pollutant, activities of urease and phosphatase, microscopic characteristics of roots were measured. Results showed that the average removals of COD, TN and TP in WH were significantly higher than that in the other systems. Interspecies competition existed in WH system, while the difference in terms of biomass gradually diminished. Furthermore, the root lengths, area, volume and tip number were higher compared to the other systems. The correlation between the removal rate of TP and activity of phosphatase in upper and bottom layer of CWs showed the opposite tendency, the distribution of plant roots in polyculture essentially impact TP removal rate in CWs. Our results provide the necessary insights for appropriately selecting different plant types for doing polyculture in CWs.

Keywords:

• Biomass production
• enzymatic activity
• plant consortium
• plant uptake
• pollutant removal

Acknowledgments

The authors thank the other members of our group, who gave us advice and suggestions regarding this work, for their selfless contributions.

Additional information

Funding

This work was supported by the key research and development project of Hunan province [2018SK2017], youth fund of Central South University of Forestry Science and Technology [QJ2018006A] and research grant of Central South University of Forestry Science and Technology [2018YJ017].