Abstract
Water purification system using aquatic plants are theoretically based on uptake of nutrients from sediments to plants. Thus there are many reports about efficient harvest of aquatic plants in various kinds of conditions for effective nutrients’ removal. The role of sediments for nutrients’ removal also well discussed up to the present. But there are only few reports about the role of aquatic animals appearing in purification system using aquatic plants. In this study we focused to the role of aquatic animals on their potentials for conversion of nutrients by using biomass and preserved nutrients in their bodies. We clarified the ratio of nutrients’ removal on water purification facilities using aquatic plant “Phragmites australis” located in Ogata-mura, Akita-ken, Japan. The total removal of nutrients calculated from concentration differences between influent and effluent. The ratio of preserved nutrients in aquatic animals are estimated about 8.6 to 13.9 % of nitrogen, 1.4 to 3.8 % of phosphorus in 4 species of aquatic animals living in this facilities such as tadpoles, aquatic earth worms, larva of dragonfly and larva of midge. These percentage are almost same level in comparison with the amount of nutrients stored in P. australis. These results suggest us aquatic animals play the important role for nutrients’ removal by their emergence or go ashore. We should design the water purification facility using aquatic plants not only aquatic plants but living space for aquatic animals.
