Adhesion of Microorganisms on the Surfaces of Various Metallic Materials Immersed in a Cooling Water Tank of the Package Type Cooling Tower
Daisuke Kuroda, Nagisa Kamakura, Hideo Ito, Hajime Ikegai, Hideyuki Kanematsu
Adhesion of microorganisms and biofilm formation on the surfaces of some single alloys and plated steels were evaluated in order to estimate the inhibition capability against biofilm formation on these materials. SS400, 304 steel and 430 steel were used for test materials. Ag, Co, Cr, Cu, Ni, Sn and Zn plated steels were also used for test materials, respectively. These specimens were immersed in a cooling water tank of the package type cooling tower for 1 month. Surface observation was carried out before and after immersion test to evaluate inhibition capability against biofilm formation. The chemical composition on the surface of each specimen was also evaluated, because of various elements such as Ca, P and Si are concentrated in biofilm during immersion test.
Adhesion of algae and extraneous matters were observed on the surface of each specimen after immersion test. The extent of increase in Ca content and adhesion of algae on the surfaces of 304 steel, 430 steel, Cr plated steel and Ni plated steel were lower than those of SS400, Ag plated steel, Co plated steel, Cu plated steel, Sn plated steel and Zn plated steel. The results for SS400 and the specimens with plated layer composed of noble elements such as Ag, Co, Cu and Sn show lower inhibition capability against biofilm formation, indicate that the iron ion was involved in biofilm formation. 304 steel, 430 steel, Cr plated steel and Ni plated steel showed higher inhibition capability against biofilm formation in this study.