Study On Nitrogen And Phosphorus Removal By Artifical Floating Beds

Removing nitrogen and phosphorus from water is an effective way toprevent surface water eutrophication, and aslo be an urgent task in theremediation of surface water. Artificial floating beds removecontaminants from water by the combined action of macrophytes,microbes and aquatic animals. As a new ecological rehabilitationtechnology, artificial floating beds have been widely used in the past threedecades. Nutrient removal abilities of reed (Phragmites australis), rice(Oryza sativa), canna (Canna indica) and calamus (Acorus calamus) werecompared in this study. We got dominant species that can be applied inthe northeast of China. The conclusions were listed as following:1. In the simulation experiment, all of four macrophytes performedwell in nitrogen and phosphorus removal to the confectedeutrophic wastewater. When HRT was10d, the differences of N and Premove efficiencies between four species were not significant. Howere,there were significant differences in the nutrient remove rates during thefirst2days of each period, and canna and reed were superior to rice andcalamus.2. In the field experiment, the nitrogen and phosphorus uptake androots level were in the order: canna> calsmus> reed> rice. The canna’s ability of nutrients removal was superior to others.3. According to the simulation and field experiments, canna and reedare the dominant species that could be applied in the northeast of China.4. In the floating beds systems of reed, rice, canna and calamus, thenitrogen and phosphorus removal rates was positively correlated withlength, surface area and volume of roots of four macrophytes. In thecondition of reed and calamus purified the simulated water with differentlevels of eutrophication, there was also a significant positive correlationbetween nutrient removal rates and root parameters. The growthcondition of root is a major factor influencing the removal ability ofplants.5. Plant uptake was the main way of nutrient removal, while thecontribution rate was36.4-77.1%for N and45.5-83.7%for P, the latterwas higher than former. The microbial activities and settlement were alsoimportant process to nutrient removal.