Roles of Plant Metabolism for Organic Matter Removal Using Water Hyacinth to Treat Sewage

Water hyacinth (Eichhornia crassipes) is a floating aquatic plant which has been employed for wastewater treatment in many part of the world. A lot of researches on the performance of aquatic plant treating sewage had been carried out and it was concluded that water hyacinth was one of the plants who had the best performance. But few reports about what role the metabolism of aquatic plants played for the organic matter removal when they are used to treat wastewater can be found. In this paper, the excretion and assimilation of water hyacinth cultivated in different mediums were investigated. It was concluded that water hyacinth excreted organic matter to their living environment and their metabolism process assimilated organic matter at the same time. When the speed of excretion and assimilation came to equivalence, the organic matter concentration tended to constant. Part of the water hyacinth excretion was easily to be degraded, and the coupling of water hyacinth assimilation and microorganism degradation would occur when microorganism existed. Using water hyacinth to treat raw sewage, the start rate of TOC removal was greatly improved because of the combination of water hyacinth assimilation and microorganism degradation.