Rhizosphere effect of three types of macrophytes during nitrogen removal process of high-loaded swine wastewater
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 ammonia-oxidizing 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.
国家科技期刊平台
NSTL
万方数据
