Two-dimensional (2-D) microscopic pore structures consisting of an array of cylindrical collectors and radial stagnation point flow cells (RSPF) were designed to study attachment and transport of Cryptosporidium parvum oocysts and Azotobacter vinlandeii bacterial strains. Real-time monitoring and quantitative analysis of recorded images revealed similarity and distinctive transport behaviors of these studied microorganisms. Microscopic evidence showed the spatial distribution of microorganisms in porous media, the dependence of attachment on swimming motility, and the controlling role of collector surface heterogeneity on microorganism attachment. For example, the results revealed that swimming motility repelled bacterial cells away from the collector surface. Swimming bacterial cells observed at 10 �m from the collector surface tripled those deposited on this surface. However, a different trend was observed for non-swimming flagellated or non-swimming non-flagellated bacteria: the number of cells deposited on the surface doubled those observed at 10 �m from the collector surface. At 20 �m and higher from the collector surface, all three strains followed the flow streamlines. Our work illustrated that swimming motility resulted in lower tendency for bacterial cells to attach to the surfaces and be more mobile in the subsurface environment.

Pore scaled transport of microorganisms

248th National Meeting (2014)

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