AWWA WQTC63987

Adsorption by activated carbon is a promising technique to remove trace pharmaceuticals (PhACs) and endocrine disrupting substances (EDS), based on its capability to remove pesticides in drinking water treatment. The objective of this research is to determine the effectiveness of granular activated carbon (GAC), for the removal of naproxen, carbamazepine, and nonlyphenol (NP) in the presence and absence of background natural organic matter. The experimental results for naproxen are presented and discussed in this paper as an example. The capacities of two common GACs (coal-based F-400 from Calgon and coconut-based TIF TE from PICA) were determined through isotherm tests on virgin carbon in ultrapure water and in post-sedimentation (PS) water from a full-scale plant treating river water. Competitive adsorption between naproxen and background organic matter in the PS water significantly decreased the adsorption capacity for naproxen on both carbons compared to that in ultrapure water, albeit to different degrees. The characteristics (i.e. Freundlich parameters K and 1/n, and initial concentration Co) of the equivalent background component (EBC), which represents all competing background compounds including natural organic matter (NOM), were determined and then used in conjunction with ideal adsorbed solution theory (IAST) to predict GAC capacities at different initial naproxen concentrations. Batch kinetic experiments showed that the preloading of NOM onto GAC greatly impacted both adsorption capacity and kinetics on F400 carbon. External mass transfer coefficients were determined by using short fixed bed (SFB) reactors, and also estimated using the Gnielinski correlation. Experimentally determined external diffusion coefficients were larger than the ones estimated by the Gnielinski correlation on virgin F400 carbon, albeit approaching the latter with increasing preloading time. In future work, isotherm and kinetic data under competitive and preloading conditions will be applied to a mass transfer model to predict the breakthrough of naproxen in GAC filters. Includes 29 references, tables, figures.