A test of three macrophyte species to reduce total nitrogen and total phosphorus from wastewater

Three aquatic macrophytes (Acorus calamus, Lythrum salicaria and Sagittaria sagittifolia) were grown in monoculture to test the relative growth rate(RGR) and abilities of removing total nitrogen(TN) and total phosphorus (TP) by the manipulative indoor experiment. A nutrient treatment consisted of four levels of nitrogen (N) and phosphorus (P) [low (14 mg L-1 N and 3 mg L-1 P) and high (56 mg L-1 N and 12 mg L-1 P)] of nutrient solution. Result revealed that the RGR of the species was significantly different, however nutrients had no significant affect on the RGR. Also the abilities of different macrophyte species to remove nitrogen and phosphorous contrast sharply with one another. The results showed that TN and TP in wastewater were significantly higher from unvegetated microcosms compared to vegetated. A. calamus was shown to be best removal effect with the removal rates of 96.4% and 71.5% at low and high concentrations of TN. Furthermore A. calamus was generally effective removal capacity of TP at low nutrient level, but the performance of L. salicaria at reducing phosphorus at high nutrient level was relatively high.