Study On Purified Efficiency Of Ecological Wastewater Treatment By Wetland Plants In Constructed Wetland

Constructed wetland is used for new ecological wastewater treatment.The method plays an important role with species selection of wetland plants and purification, technology.This experiment has taken closest to the natural wetlands, surface flow wetland system, by three repeated field experimental design, using analysis of variance, statistical analysis of multiple comparison to study the purification effects of COD, TP, NH4+-N, DO and turbidity purifying in living wastewater of different residence time and different wetland plants.The experiment results show that:1. Residence time and plant species composition for COD, TP, NH4+-N, DO and turbidity purification rate has come to a significant effect and the interaction between two factors produuce obvious or highly significant influence. By comparing the two factors, retention time is more effective to turbidity purification and plant species and its combinations affect more significantly on TP purifying effect.2. Different species and difffernt combinations of plants show great different purifying effects on COD,NH4+-N,DO. Comprehensively, reed, cattail and Canna combination produces the best effect on COD; reed, bamboo and cattail are the best combination both to NH4+-N; and TP; reed and cattail combination produces the best effect in purifying DO and reed bamboo, cattail and Canna combination best clean turbidity.3. In view of different plant species and different compositions to the turbidity purification of COD, NH4+-N, TP, any best combination all includes cattail element,which indicates cattail's stronger effect. Plant combination shows higher effect than single plant does and there is no obvious regularity to DO.4.An integrated combination of plants clean the best way, and the dominant species are "Arundo donax, cattail and Canna", and the best comprehension for NH4+-N,TP,is combination of reed bamboo, cattail and Typha and to DO the best combination is reed bamboo plus cattaill.5. In comparison, COD, NH4+-N, TP and turbidity level reduce with the variation of time, which demonstrates that in wetland system matrix, microorganisms play certain role in the sewage purification process.