The significance of biofilms in porous media

Some claim that the bacteria form continuous biofilms that restrict the pore size, while other claim that bacteria are attached in patchy aggregates that accumulate in pore throats. This contribution applies a recently developed tool from biofilm kinetics, the normalized surface loading, to interpret a wide range of experimental data from porous media experiments and biological filtration. The normalized surface loading is the actual substrate flux (i.e., rate of removal per unit surface area) divided by the minimum flux capable of supporting a deep biofilm. The analyses show that biofilms are continuous for normalized surface loadings greater than 1.0, but appear to become discontinuous for values less than about 0.25. -from Author