Survey of parasitic contamination of sewage sludges in northern Iran

Abstract

The use of sewage sludge as fertilizer in agriculture is a convenient and economic solution, but it is essential to monitor presence of parasitic contamination. This study investigated parasites in sewage sludge of wastewater treatment plant in Gorgan, Iran. This descriptive-analytical study was performed on 18 sewage sludge samples collected from wastewater treatment plant of Gorgan within 6 months with three repeatitions per month. The samples were analyzed in the laboratory of School of Public Health at Golestan University of Medical Sciences. Analysis of parasites was done using Bailenger method of counting parasites in chamber of McMaster slides with volume of 0.3 ml. The results showed that majority of parasite eggs in the sewage sludge was related to nematodes. The dominant nematode eggs detected were related to Ancylostoma duodenale, Necator americanus and Enterobious vermicolaris. However, no parasite was found in dried sewage sludge. Considering the amount of parasite eggs in the returned sludge, it is necessary to modify the treatment process. However, it is permissible to use dried sewage sludge as agricultural fertilizer.

Keywords: Parasite eggs, Protozoa, Sewage sludge, Iran