PFAS Treatment by Anion Exchange - Revision history

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Admin at 15:35, 30 October 2024

2024-10-30T15:35:22Z

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Admin at 15:35, 30 October 2024

2024-10-30T15:35:00Z

Debra Tabron at 18:03, 1 October 2024

2024-10-01T18:03:06Z

Debra Tabron at 17:52, 1 October 2024

2024-10-01T17:52:44Z

Debra Tabron at 17:42, 1 October 2024

2024-10-01T17:42:11Z

Show changes

Jhurley: /* Field Demonstrations */

2024-09-11T20:10:47Z

‎Field Demonstrations

Jhurley: /* Costs and the Importance of Treatment Criteria */

2024-09-11T20:08:32Z

‎Costs and the Importance of Treatment Criteria

Jhurley: /* Costs and the Importance of Treatment Criteria */

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‎Costs and the Importance of Treatment Criteria

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 <onlyinclude>[[Wikipedia: Ion exchange | Anion exchange]] has emerged as one of the most effective and economical technologies for treatment of water contaminated by [[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) | per- and polyfluoroalkyl substances (PFAS)]]. Anion exchange resins (AERs) are polymer beads (0.5–1 mm diameter) incorporating cationic adsorption sites that attract anionic PFAS by a combination of electrostatic and hydrophobic mechanisms. Both regenerable and single-use resin treatment systems are being investigated, and results from pilot-scale studies show that AERs can treat much greater volumes of PFAS-contaminated water than comparable amounts of [[Wikipedia: Activated carbon | granular activated carbon (GAC)]] adsorbent media. Life cycle treatment costs and environmental impacts of anion exchange and other adsorbent technologies are highly dependent upon the treatment criteria selected by site managers to determine when media is exhausted and requires replacement or regeneration.</onlyinclude><div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
 '''Related Article(s):'''
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 *[[PFAS Treatment by Electrical Discharge Plasma]]
 *[[Supercritical Water Oxidation (SCWO)]]
 '''Contributor(s):''' [[Dr. Timothy J. Strathmann]], [[Dr. Anderson Ellis]] and [[Dr. Treavor H. Boyer]]
 '''Key Resource(s):'''

← Older revision		Revision as of 15:35, 30 October 2024
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	<onlyinclude>[[Wikipedia: Ion exchange \| Anion exchange]] has emerged as one of the most effective and economical technologies for treatment of water contaminated by [[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) \| per- and polyfluoroalkyl substances (PFAS)]]. Anion exchange resins (AERs) are polymer beads (0.5–1 mm diameter) incorporating cationic adsorption sites that attract anionic PFAS by a combination of electrostatic and hydrophobic mechanisms. Both regenerable and single-use resin treatment systems are being investigated, and results from pilot-scale studies show that AERs can treat much greater volumes of PFAS-contaminated water than comparable amounts of [[Wikipedia: Activated carbon \| granular activated carbon (GAC)]] adsorbent media. Life cycle treatment costs and environmental impacts of anion exchange and other adsorbent technologies are highly dependent upon the treatment criteria selected by site managers to determine when media is exhausted and requires replacement or regeneration.</onlyinclude><div style="float:right;margin:0 0 2em 2em;">__TOC__</div>		<onlyinclude>[[Wikipedia: Ion exchange \| Anion exchange]] has emerged as one of the most effective and economical technologies for treatment of water contaminated by [[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) \| per- and polyfluoroalkyl substances (PFAS)]]. Anion exchange resins (AERs) are polymer beads (0.5–1 mm diameter) incorporating cationic adsorption sites that attract anionic PFAS by a combination of electrostatic and hydrophobic mechanisms. Both regenerable and single-use resin treatment systems are being investigated, and results from pilot-scale studies show that AERs can treat much greater volumes of PFAS-contaminated water than comparable amounts of [[Wikipedia: Activated carbon \| granular activated carbon (GAC)]] adsorbent media. Life cycle treatment costs and environmental impacts of anion exchange and other adsorbent technologies are highly dependent upon the treatment criteria selected by site managers to determine when media is exhausted and requires replacement or regeneration.</onlyinclude><div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
		+

	'''Related Article(s):'''		'''Related Article(s):'''

← Older revision		Revision as of 15:35, 30 October 2024
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−	<onlyinclude>[[Wikipedia: Ion exchange \| Anion exchange]] has emerged as one of the most effective and economical technologies for treatment of water contaminated by [[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) \| per- and polyfluoroalkyl substances (PFAS)]]. ~~</onlyinclude>~~Anion exchange resins (AERs) are polymer beads (0.5–1 mm diameter) incorporating cationic adsorption sites that attract anionic PFAS by a combination of electrostatic and hydrophobic mechanisms. Both regenerable and single-use resin treatment systems are being investigated, and results from pilot-scale studies show that AERs can treat much greater volumes of PFAS-contaminated water than comparable amounts of [[Wikipedia: Activated carbon \| granular activated carbon (GAC)]] adsorbent media. Life cycle treatment costs and environmental impacts of anion exchange and other adsorbent technologies are highly dependent upon the treatment criteria selected by site managers to determine when media is exhausted and requires replacement or regeneration.	+	<onlyinclude>[[Wikipedia: Ion exchange \| Anion exchange]] has emerged as one of the most effective and economical technologies for treatment of water contaminated by [[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) \| per- and polyfluoroalkyl substances (PFAS)]]. Anion exchange resins (AERs) are polymer beads (0.5–1 mm diameter) incorporating cationic adsorption sites that attract anionic PFAS by a combination of electrostatic and hydrophobic mechanisms. Both regenerable and single-use resin treatment systems are being investigated, and results from pilot-scale studies show that AERs can treat much greater volumes of PFAS-contaminated water than comparable amounts of [[Wikipedia: Activated carbon \| granular activated carbon (GAC)]] adsorbent media. Life cycle treatment costs and environmental impacts of anion exchange and other adsorbent technologies are highly dependent upon the treatment criteria selected by site managers to determine when media is exhausted and requires replacement or regeneration.</onlyinclude><div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
−	<div style="float:right;margin:0 0 2em 2em;">__TOC__</div>

	'''Related Article(s):'''		'''Related Article(s):'''

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 *[[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS)]]
 *[[PFAS Sources]]
 *[[PFAS Transport and Fate]]
-*[[PFAS Ex Situ Water Treatment]]
+*[[PFAS Treatment by Electrical Discharge Plasma]]
 *[[Supercritical Water Oxidation (SCWO)]]

← Older revision		Revision as of 18:03, 1 October 2024
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−	'''Contributor(s):''' [[Dr. Timothy J. Strathmann]], [[Dr. Anderson Ellis]] and Dr. Treavor H. Boyer	+	'''Contributor(s):''' [[Dr. Timothy J. Strathmann]], [[Dr. Anderson Ellis]] and [[Dr. Treavor H. Boyer]]

← Older revision		Revision as of 17:52, 1 October 2024
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−	'''Contributor(s):''' [[Dr. Timothy J. Strathmann]], Dr. Anderson Ellis and Dr. Treavor H. Boyer	+	'''Contributor(s):''' [[Dr. Timothy J. Strathmann]], [[Dr. Anderson Ellis]] and Dr. Treavor H. Boyer

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 A third pilot study compared the long-term (>1 year) performance of PFAS-selective AERs with GAC treating contaminated groundwater dominated by short-chain PFCAs<ref name="ChowEtAl2022" />. As noted in other studies, AER outperform GAC on a bed volume-normalized basis, especially for longer-chain PFCAs and PFSAs. With lower site groundwater concentrations, quantitative relationships between chain length and breakthrough was observed for both PFCAs and PFSAs, with log-linear relationships being observed between BV10 and BV50 (bed volumes at which 10% and 50% breakthrough occurs, respectively) and chain length. These investigators also noted that deviations from a linear PFAS structure (e.g., branching of the perfluoroalkyl chain) negatively affects AER adsorption to a lesser extent than GAC.
-<onlyinclude>While most pilot studies have focused on evaluating single-use AERs, pilot studies have also been undertaken to test anion exchange treatment systems employing regenerable AER</onlyinclude><ref name="WoodardEtAl2017" />. Operating lead-lag packed beds, with 5-min EBCT each, the regenerable AER delayed breakthrough of PFCAs and PFSAs compared to GAC. Effluent PFOA breakthrough from the lag bed of AER occurred after ~10,000 BVs, necessitating resin regeneration, which was accomplished by backflushing with 10 BVs of a salt brine/organic cosolvent mixture (+1 BV salt brine pre-rinse and 10 BVs potable water post-rinse). PFAS removal results using the regenerated resin were then found to be comparable with virgin resin. Preliminary tests showed that cosolvent use can be minimized by recovering from the waste regenerant mixture by distillation. A number of studies are currently underway to test the effectiveness of different technologies for destruction of PFAS concentrates in the resulting still bottoms residual<onlyinclude>. </onlyinclude>
+While most pilot studies have focused on evaluating single-use AERs, pilot studies have also been undertaken to test anion exchange treatment systems employing regenerable AER<ref name="WoodardEtAl2017" />. Operating lead-lag packed beds, with 5-min EBCT each, the regenerable AER delayed breakthrough of PFCAs and PFSAs compared to GAC. Effluent PFOA breakthrough from the lag bed of AER occurred after ~10,000 BVs, necessitating resin regeneration, which was accomplished by backflushing with 10 BVs of a salt brine/organic cosolvent mixture (+1 BV salt brine pre-rinse and 10 BVs potable water post-rinse). PFAS removal results using the regenerated resin were then found to be comparable with virgin resin. Preliminary tests showed that cosolvent use can be minimized by recovering from the waste regenerant mixture by distillation. A number of studies are currently underway to test the effectiveness of different technologies for destruction of PFAS concentrates in the resulting still bottoms residual.
 ==Costs and the Importance of Treatment Criteria==

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 <onlyinclude>Life cycle cost analyses show that anion exchange treatment is a viable alternative to GAC adsorption</onlyinclude><ref name="LiuEtAl2022" /><ref name="EllisEtAl2023" />. Like other adsorption treatment systems, single-use AER treatment systems have fairly simple design with lead-lag reactor vessels in series together with associated pumping, plumbing and any water pretreatment processes (e.g., sediment filters, process for metals removal). While similar in design to GAC treatment systems, single-use AER treatment systems can have significantly lower capital costs due to the smaller reaction vessels used (as a result of shorter required EBCTs for AER)<ref name="EllisEtAl2023" />. The smaller reactor sizes may also reduce associated costs for any structure required to house the reactors. Capital costs for regenerable AER systems are more difficult to estimate because of their added system complexity, including added infrastructure for resin regeneration, cosolvent recovery by distillation, and still bottoms management. Over the full life cycle of AER treatment systems, typically >10 years, operating costs are expected to dominate overall PFAS treatment costs<ref name="EllisEtAl2023" />. These costs are determined largely by media usage rate (MUR), which is the frequency for replacement and disposal or regeneration of exhausted resins. Despite the higher unit costs of anion exchange media relative to GAC (often ≥3-fold greater per m<sup>3</sup>), the superior adsorption capacity and PFAS affinity of AERs leads to lower MURs that more than offset this increased sorbent cost<onlyinclude>. </onlyinclude>
-<onlyinclude>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. Sites are typically contaminated with a mix of different PFAS that will breakthrough resin beds into effluent at different bed volumes of water. For example, short-chain PFCAs breakthrough much more rapidly than long-chain PFCAs and PFSAs, so selection of treatment criteria that include short-chain PFCAs like perfluorobutanoic acid (PFBA) will necessitate more frequent media replacement or regeneration than criteria focused on long-chain PFAS. </onlyinclude>Likewise, adoption of the proposed drinking water limits for PFOS and PFOA (4 ng/L each)<ref>USEPA, 2023. PFAS National Primary Drinking Water Regulation Rulemaking. 88 Federal Register, pp. 18638-18754. [https://www.federalregister.gov/documents/2023/03/29/2023-05471/pfas-national-primary-drinking-water-regulation-rulemaking Federal Register Website]</ref> in effluent of the lead vessel of a lead-lag reactor system as the breakthrough criteria will require more frequent media replacement than using a less stringent criteria (e.g., 50% breakthrough of either compound in the lead vessel). Breakthrough criteria can also affect media selection because the performance advantages of the more expensive PFAS-selective AER over regenerable AER and GAC are most apparent when media replacement/regeneration is dictated by breakthrough of long-chain PFCAs and PFSAs, and when a greater extent of media adsorption capacity is used before replacement/regeneration; these advantages shrink when media replacement/regeneration is dictated by breakthrough of short-chain PFCAs<ref name="EllisEtAl2023" /><ref name="EllisEtAl2022" /><ref name="ChowEtAl2022" />. While purchase of new media and disposal of exhausted media are minimal with regenerable AER, costs are still linked closely to regeneration frequency because of the needs for consumables (salt brine, cosolvent) and management and disposal of the resulting waste regenerant solutions, which often far exceeds media waste in terms of total waste mass and volume. These costs may be reduced by recovering cosolvent and destruction of PFAS in the resulting still bottoms<ref name="BoyerEtAl2021b" />, areas of active research and development<ref name="StrathmannEtAl2020" /><ref name="HuangEtAl2021" />
+<onlyinclude>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. </onlyinclude>Sites are typically contaminated with a mix of different PFAS that will breakthrough resin beds into effluent at different bed volumes of water. For example, short-chain PFCAs breakthrough much more rapidly than long-chain PFCAs and PFSAs, so selection of treatment criteria that include short-chain PFCAs like perfluorobutanoic acid (PFBA) will necessitate more frequent media replacement or regeneration than criteria focused on long-chain PFAS. Likewise, adoption of the proposed drinking water limits for PFOS and PFOA (4 ng/L each)<ref>USEPA, 2023. PFAS National Primary Drinking Water Regulation Rulemaking. 88 Federal Register, pp. 18638-18754. [https://www.federalregister.gov/documents/2023/03/29/2023-05471/pfas-national-primary-drinking-water-regulation-rulemaking Federal Register Website]</ref> in effluent of the lead vessel of a lead-lag reactor system as the breakthrough criteria will require more frequent media replacement than using a less stringent criteria (e.g., 50% breakthrough of either compound in the lead vessel). Breakthrough criteria can also affect media selection because the performance advantages of the more expensive PFAS-selective AER over regenerable AER and GAC are most apparent when media replacement/regeneration is dictated by breakthrough of long-chain PFCAs and PFSAs, and when a greater extent of media adsorption capacity is used before replacement/regeneration; these advantages shrink when media replacement/regeneration is dictated by breakthrough of short-chain PFCAs<ref name="EllisEtAl2023" /><ref name="EllisEtAl2022" /><ref name="ChowEtAl2022" />. While purchase of new media and disposal of exhausted media are minimal with regenerable AER, costs are still linked closely to regeneration frequency because of the needs for consumables (salt brine, cosolvent) and management and disposal of the resulting waste regenerant solutions, which often far exceeds media waste in terms of total waste mass and volume. These costs may be reduced by recovering cosolvent and destruction of PFAS in the resulting still bottoms<ref name="BoyerEtAl2021b" />, areas of active research and development<ref name="StrathmannEtAl2020" /><ref name="HuangEtAl2021" />
 ==References==