INVESTIGATING THE ROLE OF MONTMORILLONITE CLAY ON THE TRANSPORT OF CAFFEINE, BISPHENOL A, SULFAMETHOXAZOLE, AND CARBAMAZEPINE IN GROUNDWATER

Results from this study indicate the presence of montmorillonite clays can disproportionately affect the transport of wastewater contaminants in groundwater. Caffeine, pharmaceuticals, and other household products can enter groundwater from septic tanks, wastewater treatment facilities, and farm runoff and experience varying amounts of sorption or degradation depending on the nature of the specific chemicals and the substrate. Household chemicals are useful as tracers for identifying anthropogenically-influenced groundwater, but also have potential to pollute groundwater in populated areas.

In this study, laboratory column and batch experiments were conducted with four household products commonly found in groundwater (caffeine, bisphenol A, sulfamethoxazole, and carbamazepine) using an artificial soil composed of quartz playground sand and montmorillonite clay at varying concentrations (0%, 0.1%, 0.2%, 0.5% and 1.0%). Caffeine was significantly impacted by the montmorillonite, with adsorption coefficients ranging from 1.9 L/kg in the playground sand (0% clay) to 11.5 L/kg with 1% clay. Experiments with natural soils demonstrate that even minute levels of montmorillonite could make caffeine a less reliable tracer of anthropogenic activity than previously thought. Montmorillonite had less impact on bisphenol-A and carbamazepine and no significant impact on sulfamethoxazole transport.