Study on Wastewater Purification Effect of the Free Surface Wetland with Different Substrates and Plant Combination
|School||Kunming University of Science and Technology|
|Keywords||Surfce constructed wetland substrate aquatic macrophyte purification effect removal mechanism|
Constructed wetland systems have been used widely in eutrophic lake being a new sewage treatment technology.They have the advantages of better removal efficiency,lower operating costs,simpler conservation and strong bearing capability. In this paper,the free surface wetland simulation systems with different substrates and plant combinations were established to treat Baiyu River. The systems were build with soil,sediment and their admixture,and planted with three plant combinations including Sagittaria sagittifolia, Cyp-erus dealbata,Zantedeschia,Oenanthe javanica,Canna indica,Colocasia antiquorum Schoot .Scirpus validus,Acrus calamus and Iris pseudoacorus. Through experiments of static,the s-ystems’purification efficiency and their differences,and analysis the removal mechanisms of pollutants and effecting factors of simulation systems were searched. This paper was also written to provide some evidence and scientific references for the wetland restoration of Dianchi Lake shoreline. The results summed up as below:(1) In three blank control groups,the removal effecfs of systems for NH3-N,TN,TP and COD were different,the order of NH3-N was:admixture system> soil system> sediment system,the order of TN and TP as this follow,but it was being not accord with COD,the best was admixture system,and the worst was soil system.(2) The purification efficiency of constructed systems was increased by growing plant combination.(3) On anyone of three substrates conditions during the process of purifying NH3-H, TN and TP,the system of admixture substrate planted combination growing Sagittaria sagittifolia,Cyperus dealbat and Zantedeschia had best purification, and the removel rate of NH3-H was 48.95%～78.65% and the average removel rate was 63.57%. The removel rate of TN was 38.01%～66.81% and the average removel rate was 54.26%. The removel rate of TP was 38.82%～87.13% and the average removel rate was 60.61%. The better system was growing Scirpus validus,Acrus calamus and Iris pseudoacorus,the worst was growing Oenanlhe javanica,Cannaindica and Colocasia antiquorum Schoot.And during purification of COD,the system with soil growing plant combination had same order with previous results,but the systems with sediment and admixture substrate growing plant combination had different order,the best system was with admixture substrate growing Oenanthe javani-ca,Canna indica and Colocasia antiquorum Schoot, the removel rate was 24.47%～68.51% and the average removel rate was 43.03%.The worst was growing Scirpus validus,Acrus calamus and Iris pseudoacorus.(4) Under the same plant combination,the system with admixture substrate growing plant combination had better effect and stable for purification of NH3-N,TN and TP,the sediment system was lowest.When system growing plant combination with Sagittaria sagittifolia,Cyperus dealbata,Zantedeschia,the order of COD removel in according with the previous results,but the system with admixture substrate growing Scirpus validus,Acrus calamus and Iris pseudoacorus was best,the sediment system were better,and the soil system was worest. The system growing Oenanthe javanica,Canna indica and Colocasia antiquorum Schoot was accord with that.