Purification Mechanism of Low-Pollution Water in Three Submerged Plants and Analysis of Bacterial Community Structure in Plant Rhizospheres
Jingwei Feng, Binhua Cui, Buxian Yuan, Liu Zhang, Jibiao Zhang, Ai-Yong Zhang, Xiangxiang Han, Lijun Pan
Abstract
Three kinds of submerged plants (Hydrilla verticillata, Vallisneria natans, and Potamogeton wrightii Morong) were used to construct plant ponds for the removal of nitrogen, phosphorus, and organic matter in low-pollution water. The bacterial community structure in these plant rhizospheres was analyzed. Results showed that the maximum removal rates of total nitrogen (TN) and total phosphorus (TP) were observed in the H. verticillata plant ponds at 92.83% and 82.66%, respectively. Under the conditions of three different hydraulic retention times (HRT; 4, 6, and 8 days), the maximum removal rates of TN and TP in each of the three kinds of plant ponds increased with an increase in HRT. The absorption contribution rates of the three plants were 16.22% (V. natans), 20.38% (H. verticillata), and 16.97% (P. wrightii Morong) for TN; for TP, 19.16% (V. natans), 18.88% (H. verticillata), and 21.06% (P. wrightii Morong). The relative abundances of Proteobacteria in the plant rhizosphere of P. wrightii Morong, V. natans, and H. verticillata were 59.70%, 88.57%, and 68.57%, respectively. Proteobacteria played an important role in nitrogen removal for the three submerged plants. The relative abundances of heterotrophic denitrifying bacteria Rhodobacter for each of the rhizospheres were found to be 7.74% (P. wrightii Morong), 3.19% (V. natans), and 13.87% (H. verticillata), where denitrification was apparent. The results of this study provide theoretical guidance and technical support for the pollution control and ecological restoration of natural lakes and rivers.