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- Englund, Sophie, et al.
(författare)
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Removal efficiency of multiple poly- and perfluoroalkyl substances (PFASs) in drinking water using granular activated carbon (GAC) and anion exchange (AE) column tests
- 2017
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 120, s. 77-87
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Tidskriftsartikel (refereegranskat)abstract
- Poly- and perfluoroalkyl substances (PFASs) have been detected in drinking water at relatively high concentrations throughout the world which has led to implementation of regulatory guidelines for specific PFASs in drinking water in several European countries and in the U.S. The Swedish National Food Agency has determined that the drinking water of over one third of the country's municipal consumers is at risk or already affected by PFAS contamination. The present study investigated the effects of perfluorocarbon chain length, functional group and isomer structure (branched or linear) on removal of multiple PFASs using granular activated carbon (GAC, Filtrasorb (R) 400) and anion exchange (AE, Purolite (R) A600) column experiments. The removal of 14 different PFASs, i.e. the C-3-C-11, C-14 perfluoroalkyl carboxylic acids (PFCAs) (PFBA, PFPeA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnDA, PFDoDA, PFTeDA), perfluorooctane sulfonamide (FOSA), and the C-4, C-6, C-8 perfluoroalkyl sulfonic acids (PFSAs) (PFBS, PFHxS, PFOS), was monitored for a 217 day period. The results indicate the selective nature of PFAS removal as the absorbents are loaded with PFASs and dissolved organic carbon (DOC). A clear relationship between perfluorocarbon chain length and removal efficiency of PFASs using GAC and AE was found while PFASs with sulfonate functional groups displayed greater removal efficiency than those with carboxylate groups. Similarly, time to column breakthrough increased with increasing perfluorocarbon chain length and was greater for the PFSAs than the PFCAs for both GAC and AE. Shorter carbon chained PFASs such as PFBA, PFPeA, PFHxA showed desorption behavior and long-chained PFASs showed increased removal towards the end of the experiment indicating agglomeration or micelle development. Linear isomers of PFOS, PFHxS, and perfluorooctane sulfonamide (FOSA) had greater column removal efficiencies using GAC (and also for AE at greater bed volume throughput) than the branched and this difference increased at greater bed volume throughputs. The GAC and AE columns showed a poor correlation between DOC and PFAS removal efficiency. The results indicate that designers and operators of AE and GAC treatment processes must take into consideration the selective nature of PFAS removal and associated desorption of short-chain PFCAs during co-removal of multiple PFASs. (C) 2017 Elsevier Ltd. All rights reserved.
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| 3. |
- Franke, Vera, et al.
(författare)
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Efficient removal of per- and polyfluoroalkyl substances (PFASs) in drinking water treatment: nanofiltration combined with active carbon or anion exchange
- 2019
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Ingår i: Environmental science: water research & technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 5, s. 1836-1843
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Tidskriftsartikel (refereegranskat)abstract
- Society's increasing use of chemicals poses a challenge for drinking water producers. Accepted concentrations for per- and polyfluoroalkyl substances (PFASs) in finished water are lower than ever before with new regulations often enacted based on findings made possible by improved analytical techniques and correspondingly justified health concerns. Nanomembrane filtration removes compounds, including PFASs, based primarily on size-exclusion, however, treatment and/or disposal of PFAS laden membrane concentrate remains a challenge. This study combined feedwater nanofiltration with granular activated carbon (GAC) and anion exchange (AIX) for concentrate treatment. Nanofiltration removed PFAS concentrations on average by 99% including some PFASs with molecular weights smaller than the membrane nominal cutoff of 270 Da, indicating membrane rejection mechanisms additional to size-exclusion. Treatment of raw water and concentrate was compared in column tests. AIX showed up to threefold greater half-time of saturation than GAC, however with a higher rate of decreasing efficiency, while GAC removed approximately 20% of incoming PFAS concentrations consistently after treatment of 15 000 bed volumes (BVs). Overall, GAC and AIX removed 2.6-fold and 4.1-fold more PFAS mass per adsorbent volume from the concentrated retentate than from raw water indicating that the combination of nanofiltration with GAC or AIX increases the efficiency of the adsorbent materials in comparison to only using GAC or AIX filters.
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