Mineral surfaces and the sorption of bacteria in groundwater

Among the demonstrated processes influencing the transport of bacteria through aquifers, the deposition of cells on mineral surfaces is one of the most important. Bacterial sorption to clean, quartz sand yielded equilibrium, linear, isotherms, with greatest sorption at highest groundwater ionic strength. When iron-oxyhydroxide-coated sand was used, all of the added bacteria were sorbed up to a threshold beyond which no further sorption occurred. Bacterial transport was evaluated in experiments through columns of quartz sand in which three distributions of Fe(III)-oxyhydroxide-coated sand, present as 10% of the mass, were prepared. A large fraction of cells was retained: 14.7-15.8% of the cells were recovered after three pore volumes had eluted through clean quartz sand, and only 2.1-4.0% were recovered from the Fe(III)-oxyhydroxide-coated sand mixtures regardless of the spatial distribution of iron coatings.