Studies On Phytopurification And Phytoremediation Of Contaminated Waters By Zizania Latifolia Turcz. And Acorus Calamus L.

With the development of agriculture and industry, water contamination by trace metals and excess nutrients such as nitrogen and phosphorus is the main types of pollution in aquatic ecosystems. Some aquatic plants have strong abilities to'harvest'pollutants from the contaminated environment. The purification efficiency differs both among species and their organs. Therefore, it is useful to identify various species and their organs which remove the greatest amounts of contaminants. With floating culture, effects of Zizania latifolia and Acorus calamus on purifying domestic sewage and 3 types of wastewater (low concentration, medium concentration and high concentration) were studied. Stress responses and metal bioaccumulation in combined treatments of copper, zinc, lead and cadmium by the two emergent wetland plants were studied in pot experiments as well. The results were summarized as follows:Firstly, both Z. latifolia and A. calamus could grow well in the domestic sewage. The purifying efficiency of vegetated treatments was superior to unvegetated treatments significantly. The removal rates of TN by Z. latifolia, A. calamus, and the mixture were 92.8%, 92.7%, 94.9% respectively, and that of NH3-N, TP, CODCr were 95.5%, 97.4%, 96.6% and 83.9%, 94.3%, 84.7% and 83.0%, 85.5%, 86.7% respectively. A. calamus in monoculture had greater effects on purifying TP than Z. latifolia in monoculture and the mixture. There was no evidence that the two species mixture had greater effects than monocultures in this study.Secondly, Z. latifolia and A. calamus both grew best in the medium concentrated wastewater. Biomass of Z. latifolia in the low and high concentrated sewage was significantly less than in the medium. Biomass of A. calamus in the medium concentrated sewage was a little more than in the low and high concentrated sewage, but no significant differences were shown among them. The removal rates of Z. latifolia to TN, NH₃-N, TP, COD_Cr in the medium concentrated sewage were 97.40%, 95.28%, 98.48%, 71.38% respectively, and that in the high were 96.36%, 97.65%, 88.18%, 76.11% respectively. The purifying efficiency of Z. latifolia on the low concentrated wastewater was significantly less than the medium and high. Z. latifolia could act as purifying plants to purify the medium and high concentrated wastewater.