Accumulation characteristics of and removal of nitrogen and phosphorus from livestock wastewater by Polygonum hydropiper

The mining ecotype (ME) and non-mining ecotype (NME) of Polygonum hydropiper (P. hydropiper) were used as materials to study their potential removal capabilities for nitrogen (N) and phosphorus (P) with two (high and low) concentrations from livestock wastewater. The plants were harvested at 15, 30, and 45 d after planting. In treatments for both high and low concentrations, a significant increase in shoot biomass of two ecotypes of P. hydropiper (P < 0.05) was observed with growth time. The shoot biomass from ME of P. hydropiper was higher than that of NME. N and P accumulation in the shoots of two ecotypes of P. hydropiper increased with cultivation time (P < 0.05). However, the accumulation of ME was significantly higher than that of NME. The removal rate of total N (TN) and total P (TP) in the two wastewater concentrations treated by two ecotypes of P. hydropiper increased with cultivation time (P < 0.05), and the ME of P. hydropiper had a higher value than the NME. The ME of P. hydropiper removed as high as 87.47% of TN and 97.63% of TP. The results in this paper provide a theoretical basis for the use of P. hydropiper for N and P removal and proved that ME of P. hydropiper is a promising species for the phytoremediation of eutrophic waters.