Experiment on Water Purification by Different Combinations of Aquatic Plants

From August to September 2019, experiments were conducted in Lin’an, Zhejiang province on 12 combinations of aquatic plants such as Canna indica, Acorus calamus, Pontederia cordata, Lythrum salicaria, Cyperus alternifolius, Arundo donax var. versicolor, Nymphoides peltatum, Hydrocotyle vulgaris, Pistia stratiotes for determination of their purification ability of water. The results showed that it had fast purification effect at early stage, and topped the highest at the second and the third week, and then stabilized. The combination of A. calamus + C. alternifolius + P. stratiotes and P. cordata + N. peltatum+ A. donax var. versicolor had higher purification ability by the end of the 36th date of treatment, with 84% of removal rate of chemical oxygen demand (COD), over 80% of removal rate of ammonia nitrogen (NH4+-N), 83% of removal rate of the total phosphorus (TP). While the combination of A. donax var. versicolor + N. peltatum had lower purification ability.