Abstract: With hydroponic method, this paper studied the ryegrass Lolium multiflorum growth and its N and P removal under the application of septage filtrate. The results showed that a medium application rate of septage filtrate gave the highest yield of L. multiflorum. The N and P removal in the ryegrass hydroponic system was increased with increasing application rate of septage filtrate, but the water quality was declined when super high volume of septage filtrate was added. The N and P uptake by L. multiflorum had no significant difference under medium, high, and super high application rate of septage filtrate, with the maximum uptake of N and P being 13.6g·m^-2 and 3.17 g·m^-2_, respectively. The removed proportion of N and P through ryegrass uptake declined with increasing septage filtrate application rate. Under the same total load, increasing the application frequency of septage filtrate could improve ryegrass yield, water quality, and nutrients removal. To select an appropriate application rate and frequency of septage filtrate was the key in improving the nutrients removal efficiency of ryegrass hydroponic system.

Key words: Purple soil, Zn, Cd, Form distribution, Bioavailability, Path analysis