Biological Purification Effects of Three Aquatic Plants on N and P in Simulated Wastewater

With the culture experiments of three different water plants Juncus effusust L., Alternanthera Philoxeroides(Mart.)Griseb. and Ceratophyllum demersum L. in simulated waste water, the removal capacities of total nitrogen, total phosphorus by three aquatic plants were studied. The removal effects of three aquatic plants were investigated. The results showed that the highest removal rate of nitrogen was Juncus effusust L.(88.5% ~94.2%) and the lowest rate of nitrogen was Ceratophyllum demersum L.(62.7% ~71.2%). The best removal effect of phosphorus was Alternanthera Philoxeroides(Mart.)Griseb.(79.5% ~94.0%) and the secondly removal effect of phosphorus was Juncus effusust L.(82.9% ~90.1%) in the mild, moderate and highly eutrophic water. From absorption contribution on nitrogen and phosphorus of the three plants, it was found that the rates of the absorption contribution plants performed on nitrogen present were different in different eutrophication degree water.In the mild, moderate and high eutrophic water, the highest contribution rates of nitrogen were Ceratophyllum demersum L.(70.3%), Alternanthera Philoxeroides(Mart.)Griseb(65.8%) and Juncus effusust L(38.8%), respectively. In the three different eutrophic water, the highest contribution rate of phosphorus was Ceratophyllum demersum L.(60.1% ~84.8%), the secondly contribution rate of phosphorus was Alternanthera Philoxeroides(Mart.) Griseb.(55.6%~70.1%). Considering the removel rates and the contribution rates of nitrogen and phosphorus, three aquatic plants were suitable for mild, moderate wastewater.Especially in moderate rich nutrition water, the three species of aquatic plants had excellent purification ability.