Purification effects of different stubble height Oenanthe javanica (Blume) DC floating bed systems in winter in two successive experimental periods

Oenanthe javanica (Blume) DC floating beds with different cutting heights were employed to examine their purification effects on water quality in winter in two successive experimental periods. The floating bed systems could keep water body weakly acidic. The removal rate of total phosphorus by the floating bed systems was higher than 50%, and 80% of total phosphorous was removed within the first 4 days. At last, the total phosphorus concentration was 0.366 mg · L^-1 and 0.215 mg · L^-1 in two experimental periods, respectively. The removal rate of ammonium nitrogen was above 90%, with 70% removed within the first 4 days. At last, the ammonium nitrogen concentration was 0.455 mg · L^-1 and 0.522 mg · L^-1 in two experimental periods, respectively. The removal rate of nitrate nitrogen was dependent on its initial concentration, the final concentration of nitrate nitrogen was 0.262 mg · L^-1 and 0.289 mg · L^-1 in two experimental periods, respectively. The bed systems could rapidly remove nutrients in a shorter period, but less difference was observed between the floating bed systems and the control by the end of each experiment stage. There were no significant differences in the nutrients removal among the O. javanica floading beds with different cutting heights.