Abstract
Porous concrete is tried to apply to river as a river bed materials which enhance the amount of attached growth microorganisms and its biological activity. In this study, porous concrete containing zeolite was used as the riverbed materials, and nitrification biofilm forming on the riverbed was targeted. Effects of surface flow rate on nitrification biofilm formation and its activity were investigated. In a range from 5 cm/s to 40 cm/s of surface flow rate, amount of nitrifying bacteria and their activity increased with the increase of the flow rate, and the effects were shown remarkably during the initial stage. Visualization of water flow conditions near surface area of the concrete material was conducted by PTV methods, and both turbulence intensity and Reynolds stress were measured. It was also observed that the both index were increased with the increase of the flow rate. It is verified that surface flow rate give a large effects and its suitable control will give effective purifying techniques of river water.
