Biofilms are a common constituent of the subsurface and are known to influence contaminant transport; however only a few studies to date have addressed microbial controls on nanoparticle mobility in porous media. The impact of a 3-day Pantoea agglomerans biofilm on the mobility of zinc oxide (ZnO) nanoparticles was studied in column experiments containing sand and glass beads at near-neutral pH and constant ionic strength. Bare ZnO nanoparticles (bZnO-NPs) and ZnO nanoparticles capped with tri-aminopropyltriethoxysilane (cZnO-NPs) were used in the experiments. Breakthrough curves demonstrate that the biofilm particularly slowed nanoparticle migration of bZnO-NPs in glass bead columns and cZnO-NPs in sand columns. With the exception of bZnO-NPs in sand columns, biofilm-coated porous media retained more nanoparticles than those of controls without biofilm. The biofilm may bear an impact on the surface charge of the porous medium, nullifying porous medium-specific effects. Although viable cell counts (VCCs) decreased after the introduction of electrolyte and before nanoparticle transport experiments, SEM and CLSM imaging of porous medium samples taken from columns after nanoparticle transport experiments, as well as total organic carbon (TOC) measurements reveal that biofilm was present in the columns throughout the experiments. Hence, it can be concluded that even a thin amount of biofilm can hinder nanoparticle migration in small-scale porous medium experiments. Moreover, nanoparticle mobility is dependent on the binding capacity of biofilms, rather than the type of porous media.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.