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Transport of Cryptosporidium oocysts in porous media: Role of straining and physicochemical filtration

Environmental Science and Technology

By:
, , , , and
DOI: 10.1021/es049789u

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Abstract

The transport and filtration behavior of Cryptosporidium parvum oocysts in columns packed with quartz sand was systematically examined under repulsive electrostatic conditions. An increase in solution ionic strength resulted in greater oocyst deposition rates despite theoretical predictions of a significant electrostatic energy barrier to deposition. Relatively high deposition rates obtained with both oocysts and polystyrene latex particles of comparable size at low ionic strength (1 mM) suggest that a physical mechanism may play a key role in oocyst removal. Supporting experiments conducted with latex particles of varying sizes, under very low ionic strength conditions where physicochemical filtration is negligible, clearly indicated that physical straining is an important capture mechanism. The results of this study indicate that irregularity of sand grain shape (verified by SEM imaging) contributes considerably to the straining potential of the porous medium. Hence, both straining and physicochemical filtration are expected to control the removal of C. parvum oocysts in settings typical of riverbank filtration, soil infiltration, and slow sand filtration. Because classic colloid filtration theory does not account for removal by straining, these observations have important implications with respect to predictions of oocyst transport.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Transport of Cryptosporidium oocysts in porous media: Role of straining and physicochemical filtration
Series title:
Environmental Science and Technology
DOI:
10.1021/es049789u
Volume
38
Issue:
22
Year Published:
2004
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental Science and Technology
First page:
5932
Last page:
5938
Number of Pages:
7