Study on wastewater purification effect of the free surface wetland with different substrates and plant combination

Compared study on the purification efficiencies and the different of three substrates and nine plants for surface flow wetlands.The results showed that:(1) substrates absorption test, the best absorption efficiencies on ammounia, total nitrogen(TN) and total phosphrus were obtained from the soil and the combined substrate of the soil and the bottom sludge,respectively;(2) the removal efficiencies of wetland with Sagittaria sagittifolia, Cyper us dealbata and Zantedeschia was the highestunder the same substrate condition.The NH_3-N, TN and TP removal rates were 62.64%~74.29%,53.56%~65.11% and 46.98%~66.55%, respectively;(3) the combined substrates has the best removal rate w hen the plant was same in the different wetlands.lt was believed that purification effeciecies has obvious different by the combined with the different substrates and the different plants, which are caused by the different structure of the substrates and the different characteristic of the plants.