Formatted Title
From Traditional to Novel Adsorbents: Do Specific Water Matrix Effects Impact PFAS Treatment?
Background/Objectives
PFAS are persistent and harmful chemicals that can contaminate water sources and pose health risks. To treat water with PFAS, separation technologies such as adsorption are used. Adsorption removes PFAS from water and concentrates them in a small waste stream. Different types of adsorbents can be used, such as granular activated carbon (GAC), ion exchange (IX) resins, modified bentonites, and cyclodextrins. These adsorbents have different advantages and disadvantages, depending on the water quality and the PFAS concentration. To choose the best adsorbent for a specific water matrix, treatability testing is essential, as it evaluates the performance and efficiency of different adsorbents under realistic conditions.
Approach/Activities
This study summarizes the results of different laboratory experiments that evaluated the effectiveness of various materials for removing contaminants from groundwater and surface water samples obtained from different sites. The materials tested include different types of GACs, IX resins, and novel adsorbents. The laboratory tests used were batch equilibrium isotherms and rapid scale column tests (RSSCTs), which can provide useful information about the adsorption capacity of the materials and their corresponding longevity in flow-through systems used to remove contaminants such as PFAS.
Results/Lessons Learned
Isotherm tests revealed variations in adsorption capacities for the different types of adsorbents tested, which were dependent on the water matrix and the PFAS initial concentration. However, RSSCTs showed more realistic results because they use a specific contact time between water and adsorbent, which limits the adsorption capacity of some adsorbents. RSSCTs showed that total organic carbon affects the performance of GAC significantly, even with low PFAS concentrations in groundwater. PFAS compounds broke through between several thousand and 100,000 bed volumes of water treated in RSSCTs, indicating that matrix specificity plays a substantial role in adsorbent longevity. This shows why treatability studies are needed for different water matrices to evaluate treatment technologies.