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| Rhizosphere effect of three types of macrophytes during nitrogen removal process of high-loaded swine wastewater |
| Received:October 02, 2023 |
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| KeyWord:swine wastewater;constructed wetland;nitrogen;root exudate;rhizosphere microorganism |
| Author Name | Affiliation | E-mail | | XIA Menghua | Institute of Subtropical Agriculture, Chinese Academy of Sciences, Key Laboratory of Agro-ecological Processes in Subtropical Region, Changsha 410125, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | LIU Mingyu | Institute of Subtropical Agriculture, Chinese Academy of Sciences, Key Laboratory of Agro-ecological Processes in Subtropical Region, Changsha 410125, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | YE Lei | College of Engineering, Hunan Agricultural University, Changsha 410128, China | | | LI Xi | Institute of Subtropical Agriculture, Chinese Academy of Sciences, Key Laboratory of Agro-ecological Processes in Subtropical Region, Changsha 410125, China | lixi@isa.ac.cn | | LI Yuyuan | Institute of Subtropical Agriculture, Chinese Academy of Sciences, Key Laboratory of Agro-ecological Processes in Subtropical Region, Changsha 410125, China | | | WU Jinshui | Institute of Subtropical Agriculture, Chinese Academy of Sciences, Key Laboratory of Agro-ecological Processes in Subtropical Region, Changsha 410125, China | |
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| Abstract: |
| To explore the rhizosphere effect of different macrophytes during treating high-loaded swine wastewater, we built the surface flow constructed wetlands（CWs） planted with three different types of emergent plants（Canna indica, Pontederia cordata, and Iris pseudacorus）. Through a controlled field experiment, the relationships between root exudates and rhizosphere nitrogen cycle-related microorganisms were investigated. The results suggested that the CW planted with P. cordata was more effective in treating swine wastewater, and the removal efficiencies of ammonia, nitrate, and total nitrogen were 78.3%, 93.4%, and 81.2%, respectively. Compared to before the experiment, the dissolved organic carbon（DOC）secretion rates of P. cordata and I. pseudacorus root increased by 44.9% and 13.5%, respectively, while total organic acids（TOA）secretion rates of P. cordata and I. pseudacorus root increased by 125.1% and 147.5%, respectively, after the experiment. After treating swine wastewater, the CW system nitrification was dominated by ammoniaoxidizing bacteria（AOB）, and the highest abundance of AOB-amoA gene was found in I. pseudacorus rhizosphere soil at 2.6 × 108 copies·g-1. The denitrification was dominated by nirK gene, and the highest abundance of nirK gene was found in P. cordata rhizosphere soil at 4.3 × 108 copies · g-1. Anammox was also present in the rhizosphere, and the highest abundance of hzsB gene was found in P. cordata rhizosphere soil at 2.6 × 107 copies·g-1. The study demonstrated that the root secretion of DOC and TOA could stimulate the growth and reproduction of rhizosphere nitrogen cycle-related microorganisms. Moreover, they could improve the nitrogen removal efficiency in CW systems. Among the three plants, P. cordata had larger biomass and stronger root secretion ability, which had a higher application potential in ecological restoration of swine wastewater. |
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