Inactivation of Ascaris for thermal treatment and drying applications in faecal sludge

• Published in: Journal of water, sanitation, and hygiene for development sanitation, and hygiene for development, 2020-06, Vol.10 (2), p.209-218
• Main Authors: Naidoo, D., Archer, C. E., Septien, S., Appleton, C. C., Buckley, C. A.
• Format: Article
• Language: English
• Subjects: Composting; Deactivation; Drinking water; Drying; Eggs; Experiments; Heat; Heat treatment; Heat treatments; Inactivation; Indicator organisms; Moisture content; Pathogens; Sanitation; Sludge; Sludge treatment; Studies; Survival; Water baths
• ISSN: 2043-9083; 2408-9362
• DOI: 10.2166/washdev.2020.119

Ascaris lumbricoides is the most common helminth of human health importance, and the most resilient helminth found in faecal sludge. There are numerous types of sludge treatments; however, heating and drying are most commonly used for pathogen inactivation. Ascaris suum eggs were heated in a water bath at 40–55 °C for 10 seconds to 60 minutes in water, as well as heated in both urine diversion dry toilet and ventilated improved pit latrine sludge at 40 °C, 60 °C and 80 °C for times ranging from 5 seconds to 120 minutes. Eggs were also spiked into sludges of different moisture contents and incubated over 12 weeks at 25 °C, with samples analysed weekly. Overall, we concluded that eggs were inactivated at temperatures >50 °C, that the temperature–time relationship directly impacted the efficacy of heat treatment, that suspension medium had no effect, and that eggs survived better in wet rather than dry sludges.