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The goal of the ENVIRO.wiki is to make scientific and engineering research results more accessible to the target audience, facilitating the permitting, design and implementation of environmental projects. Articles are written and edited by invited experts (see Contributors) to summarize current knowledge for environmental professionals on an array of topics, with cross-linked references to reports and technical literature. |
Featured article / Biodegradation - Hydrocarbons Anion exchange has emerged as one of the most effective and economical technologies for treatment of water contaminated by per- and polyfluoroalkyl substances (PFAS). Anion exchange is an adsorptive treatment technology that uses polymeric resin beads (0.5–1 mm diameter) that incorporate cationic adsorption sites to remove anionic pollutants from water. Resins most commonly utilized for PFAS treatment are strong base anion exchange resins (SB-AERs) that incorporate quaternary ammonium cationic functional groups with hydrocarbon side chains (R-groups) that promote PFAS adsorption by a combination of electrostatic and hydrophobic mechanisms. Anion exchange treatment of water is accomplished by pumping contaminated water through fixed bed reactors filled with AERs. Water flows through the pore spaces in close contact with resin beads. Sufficient contact time needs to be provided, referred to as empty bed contact time (EBCT), to allow PFAS to diffuse from the water into the resin structure and adsorb to exchange sites. Life cycle cost analyses show that anion exchange treatment is a viable alternative to GAC adsorption. A critical parameter that will dictate media usage or regeneration, and ultimately O&M costs, is the criteria used to determine when ‘PFAS breakthrough’ is reached.
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