EFFECTS OF TRANSVERSE MIXING ON TRANSPORT OF BACTERIA THROUGH HETEROGENEOUS POROUS-MEDIA

In this paper, we examine two questions: (1) can the effects of transv erse mixing of bacteria in a system constructed to have a permeability discontinuity in the direction parallel to the flow be measured; and (2) if the effects are measurable, can they be calculated using a tran sverse dispersion coefficient estimated from experiments using a conse rvative tracer? Pulses of chloride and bacteria were transported downw ard through heterogeneous columns constructed with a tubule of coarse, quartz sand surrounding an annulus of fine, quartz sand. Pulses of ea ch were also transported through homogeneous columns of the two sands. Doubly peaked breakthrough curves resulted from the columns containin g two distinct sand sizes. Modeling of the breakthrough curves was per formed taking into account advection, dispersion, deposition, entrainm ent, and pore-size exclusion. The results revealed that transverse mix ing does occur during transport of bacteria through heterogeneous mate rial and that this mixing can be estimated using a conservative tracer .