2002 Volume 9 Issue 301 Pages 492-497
To clarify the disinfecting properties of lime compounds such as calcium hydroxide, calcium oxide and calcium carbonate, the kinetics of disinfection by the lime compounds were studied using a bacterium, Eschericia coli. The disinfection effects were found to be expressed by “Chick's low”. The disinfection rate constants of the lime compounds were compared with those of disinfection effect in NaOH solution. The disinfection rate constants of both systems increased with pH increasing, but the disinfection rate constants of the lime compounds appeared to be higher than those in the alkaline solution. Furthermore, the disinfection rate constants were increased with increasing specific surface area of the lime compounds. These results suggest that the contact phenomenon of the bacteria to the strong alkaline surfaces on these lime compounds is most important factor of the disinfection mechanism.
To evaluate the disinfective efficiency of the lime compounds, the C·t values were calculated from the time for 99% disinfections and the concentrations of the disinfectants were compared with those of usual disinfectants. The lime compounds were found to be stronger disinfectants than Ag and the efficiency of the disinfection by calcium hydroxide was almost same as that by chloramine. Thus, the lime compounds seem to have the feasibility as practical water disinfectants instead of chlorine.