The researchers studied how adding lime to sewage sludge affects its microbiological quality. They found that adding lime at pH levels of 11 and 12 can effectively reduce harmful bacteria like Salmonella and fecal coliform in the sludge. However, the reduction of parasite eggs was not as high at these pH levels. The treated sludge met environmental standards for safety after 2 and 24 hours, but did not fully meet guidelines for pathogen reduction in terms of parasite eggs at higher pH levels. Overall, lime stabilization can improve the safety of sewage sludge for agricultural use.