Contaminants of emerging concern (CECs), including pesticides, pharmaceuticals and personal care products, are increasingly being detected at low levels in surface water and groundwater that serve as drinking water sources. It is not desirable to have these biologically-active compounds present in finished drinking water because there are possible adverse effects on the consumer and certain negative consequences in terms of public perception. A biologically-active filter has the potential to remove many of these CECs. In this study, the removal of CECs was compared in pilot-scale biologically-active granular activated carbon (GAC)-sand and anthracite-sand filters. The comparison of removal efficiencies between the non-sorptive anthracite-sand filters and the GAC filters permits determination of the relative roles of sorption and biodegradation in CECs removal. Based on a survey of CECs occurrence in drinking water, eight of the most commonly detected compounds were selected for this study: atenolol, atrazine, carbamazepine, fluoxetine, gemfibrozil, metolachlor, sulfamethoxazole and tris(2-chloroethyl) phosphate. Environmentally relevant levels (200-2000 ng/L) of each CEC were dosed before the biofilters and the removal efficiency was determined by comparing the concentrations before and after biofiltration. Quantification of the CECs was performed using solid-phase extraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). To fully evaluate the performance of the biofilters, turbidity/particle removal and filter run times were also determined. Our results show that GAC-sand biofilters performed significantly better in terms of removal of all selected CECs than the anthracite-sand biofilters over a range of operational conditions (e.g., loading rate of 2 or 4 gpm/ft<sup>2</sup>, temperature of 5 or 25 °C, and CEC dosages). Also, the GAC-sand biofilters were similarly effective at particle removal, had longer filter run times and were more effective at removing other dissolved contaminants including taste and odor compounds (e.g., geosmin). We are currently investigating the adsorption capacities and kinetics of all selected CECs to GAC by performing batch sorption experiments and modeling simulations. This study will provide guidance to assist water utilities in achieving removal of multiple CECs using biofiltration without compromising the particle removal performance requirements of the filtration process.

Effects of temperature and filtration rate on removal of contaminants of emerging concern (CECs) in biologically-active GAC filters

254th National Meeting (2017)

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