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Five small vertical flow constructed wetland systems were built out in the field and each system was constructed as three tanks cascade connection with“downward-upward-upward”influent direction. The wasted plastic bottles and three kinds of gravels were used as the substrate in five systems, while No.1,2,3 thick gravel strengthening the plastic bottles, No.4 thin gravel loading into the bottles, No.5 mixed gravels loading into the system. Based on the same plantations, the same & different substrate filled in the systems and the different synchronous number, the purification of the polluted water in the city stream was studied. And the results were described as follows:1.To the treatments of three kinds of the substrate of the construction wetlands, the average removal rates were 61.3%,49.2% and 53.0% for CODMn,respectively, they were 81.6%,68.4%,71.0% for NH3N, and 90.7%,90.1%,90.1% for TP. The wasted plastic bottles are kinds of new substrate of wetlands, while strengthened by thick grovel , is significant better than the other two types.2.Among three same systems, according to the results of Spring and Winter treatments, there was no significant distinction of nutrient removal（p>0.05）,such as CODMn、NH3-N & TP. In total, the wetlands systems were very stable, no significant distinction between the same ones. The identity and durability is relatively ideal reference for Engineering research or construction.3. Parallel 1,2,3,4 or 5 suites of the wetlands and got the results including the removal rate of CODMn,NH3N and TP. There were no significant distinction between each two treatments. The parallels dos well in the rate of removal ,CODMn、NH3N and TP.The study fully explored the feasibility of using the wasted plastic bottles as the matrix of the constructed wetlands substrate, the stability of continuous operation and the necessary parameter while the wetland system being designed or built. This study fulfilled the blank of the field. At the same time, the wetland system covers an small area, flows smoothly and gets a good scenic effects. The study has the significance of China in the field of sewages treating, especially the urban rivers,the lakes and the rural life sewages.
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