Effect of Sewage Sludge Solar Drying Technology on Inactivation of Select Indicator Microorganisms

The sanitization effectiveness of sewage sludge solar drying was examined in the aspect of limiting the transmission of pathogenic microorganisms into the environment. The survival rates of indicator bacteria E. coli, faecal streptococci, and rods of Salmonella SenftenbergW775, as well as the eggs of the intestinal parasite Ascaris suum were assessed in dried sludge. The results indicate that the process of solar drying in the studied cycle was not effective and did not eliminated microorganisms to a sufficient degree. The number of the bacterial population of interest decreased only by 2 log10. The percentage of live eggs of A. suum after 28 days of the process was more than 90%.