In order to investigate macrophyte role on the waster water purification and select appropriate native vegetable to built plant filter in constructed wetland

four vertical flow constructed wetlands with river sand as their substrates were made. Among them

number 1 had Grassleaved Sweetflag(Acorus gramineus Soland.)

number 2 had Rush (Juncus effucus Linn)

number 3 had Butterfly Swordflag(Iris japonica Thunb.)

and number 4 had no vegetable (CK). Within lower concentration of total nitrogen (TN) (<30 mg/L)

the constructed wetlands with or without macrophytes had better effects on removal TN form domestic sewage and had little difference in treatment efficiency. When concentration of TN increased

the purified efficiency of all constructed wetlands had decreased to some extent. The constructed wetlands with vegetable remained higher efficiency than that constructed wetland without vegetable in purification of TN in treatment waster water. Among the constructed wetlands with vegetables

Number 1 had higher purified efficiency of TN than number 2 and number3. For total phosphorus (TP) removal

all of constructed wetlands had a good performance on removal of phosphorus form domestic sewage due to lower concentration of phosphorus in domestic sewage (<20 mg/L). Although substrates were unsaturated with phosphorus

the vegetable had yet absorbed more phosphorus. Of all vegetables

Grassleaved Sweetflag had a better ability to clean phosphorus than Butterfly Swordflag and Rush. The biomass and content of nitrogen

phosphorus in vegetable body were the main factors affected the ability of vegetable on cleaning nitrogen and phosphorus form waster water

because the vegetable absorbs nitrogen and phosphorus as its physical need during its growth. Besides nitrogen absorption

the nitrification and denitrification led by microorganism around root can enhance the wetland performance on removal nitrogen form domestic sewage. The vertical flow constructed wetland is better instrument for treating waster water with lower concentration of pollutants and should be widely used in the future.