Effect of temperature and shear stress on the viability of Ascaris suum

Ascaris eggs are commonly used as a bioindicator to test the success of waste treatment systems. The ability to inactivate this organism's eggs indicates probable destruction of a variety of pathogens. The intent of these experiments was to determine operational parameters for a conical-augur d...

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Bibliographic Details
Published in:Journal of water, sanitation, and hygiene for development sanitation, and hygiene for development, 2015-09, Vol.5 (3), p.402-411
Main Authors: Thomas, J E, Podichetty, J T, Shi, Y, Belcher, D, Dunlap, R, McNamara, K, Reichard, M V, Smay, J, Johannes, A J, Foutch, G L
Format: Article
Language:English
Subjects:
Alkalizing
Ascaris suum
Bioindicators
Deactivation
Deoxyribonucleic acid
Destruction
DNA
Eggs
Feces
Friction
Heat
Hogs
Human wastes
Inactivation
Indicator organisms
Indicator species
Literature reviews
Mechanical stimuli
Nematodes
Parasites
Parasitology
Pathogens
Residence time
Shear stress
Solid wastes
Studies
Temperature effects
Viability
Viscometry
Waste treatment
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Summary:Ascaris eggs are commonly used as a bioindicator to test the success of waste treatment systems. The ability to inactivate this organism's eggs indicates probable destruction of a variety of pathogens. The intent of these experiments was to determine operational parameters for a conical-augur device to treat human solid waste in a time-efficient manner (seconds), without exogenous chemicals (e.g. lime, an alkalizing agent) or an external heat source. Literature reviews and independent viscometry experiments established a target temperature range and residence time within the device. The ability of applied shear force to inactivate Ascaris suum, directly or indirectly, was assessed using viscometry. Shear force alone, as friction, failed to inactivate A. suum eggs. However, shear force was used to generate sufficient heat in a human-fecal simulant to inactivate A. suum eggs under a variety of test conditions. Target operating conditions for the conical-augur device were 70 °C with a 6-s residence time; increasing the temperature allowed for reduced residence time to achieve A. suum inactivation.
ISSN:2043-9083
2408-9362
DOI:10.2166/washdev.2015.175