Effects of Different Aquatic Economic Plants on Water Purification in Lake Nansi Eutrophication

Zizania latifolia，Phragmites australis，Acorus calanus，Trapa japonica，Nelumbo nucifera and Euryales semen were cultured in Lake Nansi shallow water，waste ponds，the water of subsided land and estuarine waters into the lake for phytodecontamination.Contents of total nitrogen（TN），total phosphorus（TP），ammonia（NH3-N）and chemical oxygen demand（COD）in the domestic wastewater were tested during growth of these six plants.Results showed that，six aquatic economic plants could significantly reduce TN，TP，NH3-N and COD contents，with better purification capability.At the same ecoregions，removal rates of four pollutants applied with Zizania latifolia were higher than those applied with Trapa japonica.Compared with the same aquatic economic plants（Zizania latifolia and Trapa japonica ），removal rates of four pollutants were declining along with pollutant content of ecoregions was reduced，and removal rates of Zizania latifolia treatment was significantly higher than those of Trapa japonica treatment.From quality of removal rate，performance of removal TN，Zizania latifolia>Trapa japonica> Phragmites australis > Nelumbo nucifera > Acorus calanus > Euryales semen，for performance of removal TP，Zizania latifolia>Nelumbo nucifera>Euryales semen>Acorus calanus>Phragmites australis>Trapa japonica，for performance of removal NH3-N，Zizania latifolia>Phragmites australis>Nelumbo nucifera，Trapa japonica>Acorus calanus>Euryales semen，for performance of removal COD efficiency，Acorus calanus>Zizania latifolia>Phragmites australis>Nelumbo nucifera，Trapa japonica>Euryales semen.Zizania latifolia was more capable of removing TN，TP，NH3-N and COD than Phragmites australis，Nelumbo nucifera，Trapa japonica，Acorus calanus and Euryales semen.Therefore，Zizania latifolia was cultured as pioneer plants for water purification in eutrophication water of Lake Nansi and similar lakes.