Examining granular activated carbon adsorption of organic contaminants from water: Endocrine disruptors/pharmaceuticals, methyl tert-butyl ether, and benzene

Granular activated carbon (GAC) is a widely used and efficient method for removing organic contaminants from drinking water. The work herein examines the use of GAC for removing three contaminants of interest: (i) endocrine disruptors, pharmaceuticals, and personal care products; (ii) methyl tert-butyl ether (MTBE); and (iii) benzene. Each of these contaminants occurs in drinking water sources between part-per-billion (ppb, mug/L) and part-per-trillion (ppt, ng/L) concentrations.;With detection limits at part-per-trillion (ppt) levels, endocrine-disrupting compounds (EDCs) and pharmaceuticals and personal care products (PPCPs) are now identifiable in many drinking waters. This study assessed sorption of 29 EDCs/PPCPs at ppt concentrations using GAC rapid small-scale column tests (RSSCTs). To better understand the adsorption behavior of EDCs/PPCPs at ppt levels, a quantitative structure-activity relationship (QSAR) model was developed using the observed bed volumes to breakthrough, carbon properties, and a defined set of molecular properties and descriptors.;As a relatively water-soluble gasoline additive, MTBE is found in many source waters. The removal of MTBE in RSSCTs was appraised and compared to GAC pore size and empty-bed contact time (EBCT) to determine the influences of these parameters. The performance of seven hydrophobic GACs at three small-scale EBCTs was statistically compared to the pore volume distributions of the GACs. By limiting access to micropores, mesopore volume was shown to be the most controlling factor of the analyzed parameters for RSSCT capacity. The observed mass transfer rate increased with micropore volume and decrease with mesopore volume.;Due to shipping of gasoline on the Ohio River, the Greater Cincinnati Water Works can be heavily impacted by spills, including relatively soluble benzene. The objective of the work herein was to improve the regeneration protocol for benzene removal from the influent Cincinnati water. RSSCTs for benzene removal were performed using a virgin Filtrasorb 400 (F400) GAC, a GAC regenerated at the Greater Cincinnati Water Works (GCWW), three GACs regenerated at Penn State University, and three pilot-scale GACs produced at the GCWW. Spent GAC was acquired from the GCWW and regenerated at PSU via protocols varying the use of steam and treatment time in a thermogravimetric analyzer. These lab-scale regeneration protocols were then applied at the pilot-scale using a reactor at the GCWW. Pilot-scale regeneration produced a GAC with improved benzene removal as compared to the standard regenerated GAC.