Transport of Cryptosporidium parvum oocysts through three substrates was used to determine dispersion, retardation, and first-order decay parameters for the convective dispersion equation (CDE).
Pulses of diluted Holstein calf feces containing oocysts were passed through saturated columns packed with either glass beads, coarse sand, or shale aggregate.
Effluent chloride breakthrough curves (BTCs) were used to fit pore water velocities and dispersions for each column to the CDE.
These pore water velocities were then used to fit dispersion, retardation and first-order decay factors to the CDE for C. parvum oocyst BTCs for each column.
Dispersion coefficients for oocysts averaged 0.8 cm2 s-1 in glass beads, 1.7 cm2 s-1in sand, and 1.3 cm2 s-1 in shale aggregate.
The ratio of oocyst dispersion to chloride dispersion was<1 for all substrates, suggesting oocysts experienced less shear and turbulence than the pore water.
Diffusivities of 0.07 cm for glass beads, 0.15 cm for sand, and 0.09 cm for shale aggregate show that facilitated transport in sand was greater than in the other two substrates.
Retardation coefficients for oocysts averaged 1.0 in glass beads and sand and 0.9 in shale aggregate, indicating oocysts did not adhere to these substrates.
First-order decay coefficients of 0.5 s-1 for glass beads, 0.8 s-1 for sand, and 0.6 s-1 for shale aggregate indicate significantly higher removal rates in the sand columns. (...)
Mots-clés Pascal : Oocyste, Relation dispersion, Epidémiologie, Transmission, Pollution eau, Fèces, Eau surface, Modèle mathématique, Effluent liquide, Cryptosporidium parvum, Apicomplexa, Protozoa, Parasite
Mots-clés Pascal anglais : Oocyst, Dispersion relation, Epidemiology, Transmission, Water pollution, Feces, Surface water, Mathematical model, Liquid effluent, Cryptosporidium parvum, Apicomplexa, Protozoa, Parasite
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Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 99-0416830
Code Inist : 002B30A02A. Création : 22/03/2000.