Reduction for the formation of urinal's scales by ceramics having Ag-doped glaze

The resistance of Ag-doped antibacterial ceramics for the scales sticking to urinals was investigated. The scales sampled from actual urinal mainly consisted of hydroxyapatite. Similar hydroxyapatite was formed experimentally by using the urease medium containing Ca. The hydroxyapatite was precipitated from the medium with an increasing in pH. The urease medium containing Ca having microorganisms, which were sampled from an actual urinal, was dropped on an Ag-doped antibacterial ceramic, an ordinary ceramic, and a polystyrene petri dish, and then cultured at room temperature. Although viable count in the medium on the ordinary ceramic and polystyrene petri dish increased after cultivating for 23d, viable count in the medium on the antibacterial ceramic decreased. The pH of the medium on the ordinary ceramic and the polystyrene petri dish increased and precipitation of hydroxyapatite was observed. In the case of the antibacterial ceramic, the pH did not change and precipitation was not observed. In addition the antibacterial ceramic suppressed the generation of NH₃ gas as compared with the others. The result give a possibility that antibacterial ceramics can reduced the scales of actual urinals.