Regeneration of per- and polyfluoroalkyl substance-laden granular activated carbon using a solvent based technology
Per- and polyfluoroalkyl substances (PFAS) are a large class of chemicals widely used for many commercial and industrial applications and have resulted in contamination at sites across globally. Pump-and-treat systems, groundwater extraction, and ex situ treatment using granular activated carbon (GA...
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| Published in: | Journal of environmental management Vol. 289; p. 112439 |
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| Main Authors: | , , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
England
Elsevier Ltd
01-07-2021
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Per- and polyfluoroalkyl substances (PFAS) are a large class of chemicals widely used for many commercial and industrial applications and have resulted in contamination at sites across globally. Pump-and-treat systems, groundwater extraction, and ex situ treatment using granular activated carbon (GAC) are being implemented, either in full or pilot scale, to treat PFAS-impacted groundwater and drinking water. The only current method of regenerating spent GAC is to reactivate it at temperatures greater than 1000 °C, which requires large amounts of energy and is quite expensive. This research focused on development and demonstration of an effective GAC regeneration technology using a solvent-based method for PFAS-laden GAC used in water treatment. Two different organic solvents (ethanol and isopropyl alcohol) with 0.5% and 1.0% ammonium hydroxide (NH4OH) as a base additive were tested to determine the most effective regenerant solution to remove PFAS from the contaminated GAC. Based on column tests using laboratory-contaminated GAC with perfluorooctanoic acid (PFOA) and perfluorooctanoic sulfonate (PFOS), the solvent-base mix (SBM) of ethanol with 0.5% NH4OH was found to be the optimum performing regenerant solution. The GAC life span assessment showed that solvent-regenerated GAC performed similar to virgin GAC without losing its optimal performance of PFAS sorption. Further, the solvent-regenerated GAC showed optimal performance even after four cycles of solvent regenerations tested using the optimum SBM. Average percent removal in laboratory-contaminated GAC using the optimum SBM was 65% and 93% for PFOS and PFOA, respectively. Four field-spent GAC samples were also regenerated using the optimum SBM. Percent removal from these samples was found to be in range of 55%–68%. The type of GAC used, level of contamination and type of PFAS present, water type and quality, and the presence of co-contaminants may have influenced the removal capacity. Distillation experiments have shown that it is feasible to concentrate the spent solvent prior to disposal, which reduces the amount of PFAS-contaminated solvent waste produced in regeneration cycles.
•Laboratory contaminated and spent field GAC can be regenerated for future use.•Ethanol with 0.5% (v/v) NH4OH was the optimum performing solvent regenerant.•PFAS-laden GAC can be regenerated multiple times using a solvent-based technology.•Similar PFAS sorption and better PFAS removal observed from solvent regenerated GAC.•PFAS-containing regenerant solvent can be concentrated for destruction or disposal. |
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| Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0301-4797 1095-8630 |
| DOI: | 10.1016/j.jenvman.2021.112439 |