USE OF HYDRATED LIME FOR DISINFECTION OF MODEL PATHOGENS SALMONELLA-TYPHIMURIUM AND ASCARIS-SUUM IN SEWAGE SLUDGES

Hydrated lime was lethal to the strain of Salmonella typhimurium (Sk 1 4/39) after 60 min of exposure. In the control without addition of hyd rated lime this strain was still viable after 168 hours, counting 6.1 x 10(5) pathogens/l mi sludge. 168-hr disinfection of primary sludges with 10 g/l hydrated lime showed no significant reduction in the viabi lity of Ascaris suum eggs. In three experiments, the number of viable eggs was reduced only by 3.6%. Indicator microorganisms, except psychr ophilic ones that survive for only 24 hr, were destroyed after 60 min of exposure. The temperature of stabilized sludges did not vary consid erably during experiments, ranging between 21 and 25 degrees C. With t he addition of Ca(OH)(2), sludge pH increased to the values for GOD, o rganic matters and total nitrogen were reduced throughout the experime nts. The values for sludge dry residues remained unchanged.