Comparative Analysis of Purification Effect of Different Wetland Plant Community Allocation on High Concentration Wastewater

Plant is an important component of wetland ecosystem. Species allocation of wetland plant community plays an important role in the purification of high concentration wastewater in wetland. Four common plant species in wetland were selected, including fennel, rhombus, goldfish algae and ricinus. Four different plant communities were constructed by different allocation methods: Zizania Caduciflora-Ceratophyllum Demersum -Ceratophyllum Demersum (Z-C-C), Zizania Caduciflora-Trapa incisa -Ceratophyllum Demersum (Z-T-C), Zizania Caduciflora-Potamogeton Pectinatus I -Potamogeton Pectinatus I (Z-P-P), and Zizania Caduciflora-Potamogeton Pectinatus -Ceratophyllum Demersum (Z-P-C). The results showed that the purification effect of constructed wetlands with four different plant communities was different. After treatment with Z-C-C community, the CODCr reduction rate of water body was 50.56 +/- 1.98%, significantly lower than that of Z-T-C community (69.66 +/- 4.15)%, Z-P-P community (64.29 +/- 1.05)%, Z-P-C community (66.67 +/- 1.13)% (P < 0.05); and after treatment with Z-T-C community, the TN reduction rate of water body was (24.69 +/- 4.64)%. The removal rates of NH4 +-N in Z-C-C community were significantly lower than those in Z-C-C community (53.29 +/- 0.71)%, Z-P-P community (53.36 +/- 2.04)%, Z-P-C community (54.44 +/- 0.29)% (P < 0.05). The removal rates of NH4 +-N in each community were significantly different (P < 0.05), which are (71.77 +/- 0.37)%, (67.22 S 0.53)%, (69.22 S 0.13)%, and (80.85 S 0.31)%, respectively. The results showed that the purification effect of three plant allocation modes was better than that of two plant allocation modes; the removal effect of nitrogen in constructed wetlands could be improved by increasing the allocation proportion of submerged plants appropriately; the plants with developed roots had stronger purification effect; the accumulation of total nitrogen (TN) and total phosphorus (TP) in wetlands had significant linear relationship with the concentration and biomass.