Nutrient Removal Rate and Heat Flux through Floating Canna Culture System in Eutrophied Water

The floating culture system is a water purification method using the ability of plants for nutrient removal. Since the appropriate management of the floating culture system in eutrophied water depends on the characteristics of the water body, like its shape or depth, it is impossible to make a general guideline. Therefore, as part of constructing a numerical prediction model of the flow and water quality in waters where the floating culture system is installed, a test tank experiment, using canna as plant, was conducted to parameterize the effect of the floating culture system, as a boundary condition, on the flow and water quality. The result of plant growth and water quality measurement shows that the growth rate of canna changes significantly with the phosphorus concentration in water; the relation between the removal rate of TP and the phosphorus concentration is unique. Regarding the DO concentration in tanks with floating culture system, it decreased because the system prevented aeration and blocked solar radiation at the water surface. Moreover, the water temperature measurement reveals that the shielding ratio of heat flux through the system depends strongly on the material of floating board and is approximately constant regardless of the plant's growth rate. It is concluded from the result that TP removal rate can be expressed by using phosphorus concentration in the water and heat flux shielding ratio can be set as a constant, using this canna floating culture system.