AWWA WQTC65994

The removal of trace anionic organic acids with carboxylic functional groups, such as pharmaceutically active compounds (PhACs), by anion exchange resins was found to be the sum of the physical adsorption of the molecule plus the ion exchange (IX) of the ion. The performance can be modeled by applying existing IX and adsorption equilibrium theories. For example, at a pH above 7, diclofenac (DCF, pKa 4.2) is completely dissociated and physical adsorption as well as ion exchange play a role in removing the ionized DCF, that is, the ionized target compounds can be adsorbed or ion exchanged by anionic resins. Removal of ibuprofen (IBP) and diclofenac (DCF) were evaluated at environmentally relevant concentrations (< 100 ng/L) and at higher concentrations (> 10 mg/L). These target compounds were selected for this work because they can be used as surrogates for trace anionic organic compounds in water. The overall objective was to develop combined adsorption and ion exchange models and to evaluate the relation between the resin dose needed and the removal of trace anionic organic compounds in the presence of competing anionic organic compounds present in natural organic matter (NOM)/effluent organic matter (EfOM) and inorganic compounds (e.g. sulfate) from wastewater impacted drinking water sources. Includes table, figures.