Effects of surface characteristics on the transport of multiple Escherichia coli isolates in large scale columns of quartz sand - Transport of Multiple Escherichia Coli Transport in Saturated Porous Media - page 17

2.3.2 Breakthrough curves and sticking efficiencies

An example of one experiment with 7 normalized breakthrough curves, measured at the 7
sampling ports is shown in Fig. 2.1 for UCFL-263 in DI. The pulse with E. coli suspension was
detected at every sampling port, while peak concentrations reduced with transported distance.
Each of the other E. coli strains exhibited a similar trend in breakthrough curves (data not
shown).

1.0

0.13m
0.33m
0.83m
1.33m
2.33m
3.33m
4.83m

0.8

0.6

0.4

0.2

0.0

0 1 2 3 4 5 6

Time (hours)

Figure 2.1: Breakthrough curve of UCFL-263 in DI. Error bars indicate variation between

two duplicate plate counts

In spite of the general trend, each strain exhibited a distinctly different transport behavior with
respect to relative breakthrough at all 7 sampling ports. These differences in transport behavior
also became apparent from the calculated sticking efficiencies for all E. coli strains at all
sampling ports in both DI and AGW ( Figs. 2.2 a and b ) . In both DI and AGW, a reduction of the
sticking efficiency values was observed, with a comparatively stickier fraction of the cells being
retained within 1.33 m from the column inlet, and a fraction exhibiting slow attachment
(transport distance > 1.33 m). The total inter-strain sticking efficiency variations in both DI and
AGW were around 1 log-unit (compare UCFL-94 and UCFL-348), while intra-strain sticking
efficiency variation was around 0.5 log-unit in DI, and around 1 log-unit in AGW. UCFL-94
exhibited the lowest sticking efficiencies in both DI and in AGW, while UCFL-348 had highest
sticking efficiencies. In AGW, UCFL-348 was completely retained within a travel distance of
only 0.13 m.