A study on advanced water treatment of primarily treated municipal sewage by constructed wetlandreveals that constructed wetland is effective for treating secondary water and water quality can be considerably improved after the treatment.Six common aquatic plant species in West China were chosen to study theireffects of water treatment in different times using the three proxies of COD

BOD5and NH4+ -N.The studyshows that treatment efficiency of different plants on different wastes is very different in different times.Thetreatment efficiency of each species reaches its maximum in August.Among the six species

Zizania latifolia works most efficiently on the three wastes.The treatment efficiencies of Acorus calamus Linn andPhragmitescommunis Trirn are medium.Sagittariasagittifoliais the least efficient.Natural lake and constructed wetland can be used for advanced treatment of municipal sewage.Aquatic plant selection is very important for the treatment process.