Lolium Perenne as the Cultivation Plant in Hydroponic Ditch and Constructed Wetland to Improve Wastewater Treatment Efficiency in a Cold Region.

To improve wastewater treatment efficiency by hydroponic ditches (HDs) and hybrid constructed wetlands (CWs) in cold regions and create evergreen landscape in cold periods, a research on them cultivated with Lolium perenne at depths of 10 cm and 60 cm were carried out. Water temperature of 10 °C was as the boundary between cold and non-cold periods. During the 2 years' experiment, L. perenne grew well, with better growth characteristics in the second year than that in the first year. In the cold period of the second year, when large-area freezing occurred in the culture bed, L. perenne was still clearly proliferating and kept evergreen. Meanwhile, the removal efficiencies of COD, NH -N and TP increased, especially NH -N removal increasing significantly ( p < 0.01), which correlated to the growth characteristics of L. perenne (r = 0.487 ~ 0.837, p < 0.05). In cold period of the second year, although cold climate restricted the pollutants removal, the efficiencies were still maintained around 30.0 %, 50.8 % and 55.8 % in COD removal, 82.8 %, 92.5 % and 68.6 % in NH -N removal, and 27.7 %, 40.3 % and 42.3 % in TP removal in the 10 cm HD and the two hybrid CWs. Therefore, L. perenne can be adopted as a cultivated plant in HDs and CWs in cold regions. [ABSTRACT FROM AUTHOR]