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Removal and Deactivation of Intestinal Parasites in Aerobic Mesophilic Composting Reactor for Urine Diverting Composting Toilet

ABSTRACT. Urine diverting composting toilets are becoming increasingly popular and are promoted to sanitize human excreta for recycling them into fertilizer. This study aimed to assess the removal and deactivation of intestinal parasites during the composting process. Batch experiments were conducted by composting human feces in an aerobic composting reactor using shea nut shells as bulky matrix. During 60 composting days, the removal of helminthes eggs and protozoa cysts was assessed and compared with the removal of indicator bacteria and pathogenic bacteria. The bacteria were analyzed by the single layer method on selective media and parasites were counted directly by microscope after compost preparation. The viability of helminthes eggs and protozoan cysts was assessed by a staining exclusion dyeing method. At low temperature, desiccation and alkaline pH obtained during the composting process could not completely destroy indicator bacteria while Salmonella sp. was eliminated after 30 composting days. Entamoeba hystolitica cysts were present in feces at a higher concentration (854/g mean) than Ascaris lumbricoides eggs (204/g mean). The composting process had reduced the total number of Ascaris eggs after 35 days while Entamoeba cysts were still present (beyond 54/g cysts) after 60 composting days. There were no viable Ascaris eggs after 30 days while the viability of Entamoeba cysts was still up 31%. In high concentration, Entamoeba cysts had survived stronger than Ascaris eggs during the composting process. Because of the persistence of some pathogens in compost both Ascaris eggs and Entamoeba cysts are good indicators for parasite removal.