Destruction of PFAS Via an Oxidation Process and Apparatus Suitable for Transportation to Contaminated Sites

Patent metadata

Field	Value
Publication number	US-2020407241-A1
Application number	US-202016916085-A
Country	US
Kind code	A1
Filing date	Jun 29, 2020
Priority date	Jun 28, 2019
Publication date	Dec 31, 2020
Grant date	—

Abstract

Per- and polyfluoroalkyl substances (PFAS) are destroyed by oxidation in supercritical conditions. PFAS in water can be concentrated and prepared for destruction in a pretreatment phase. Following annihilation of the PFAS in supercritical conditions to levels below 5 parts per trillion (ppt), the water effluent can be used to recover heat, returned to sub-critical conditions, and then released back into the environment.

First claim

1 . A method of destroying PFAS in a PFAS-containing aqueous mixture, comprising:
subjecting the PFAS-containing aqueous mixture to a separation procedure and separating the PFAS-containing aqueous mixture into:
a PFAS-enriched fraction and a PFAS-depleted fraction;
heating at least a portion of the PFAS-depleted fraction to a temperature of at least 300° C. to form a heated PFAS-depleted fraction; prior to a supercritical destruction phase, combining the heated PFAS-depleted fraction with a PFAS-enriched fraction to form a hot PFAS-containing aqueous mixture; or
a first salt-enriched fraction and a salt-depleted fraction, heating the salt-depleted fraction to a temperature of at least 300° C. to form a heated salt-depleted fraction; prior to a supercritical destruction phase, combining the heated salt-depleted fraction with a lower temperature first fraction to form a hot PFAS-containing aqueous mixture;
and
reacting the hot PFAS-containing aqueous mixture with an oxidant under supercritical conditions.

2 . The method of claim 1 wherein the PFAS-containing aqueous mixture is separated into a first salt-enriched fraction and a salt-depleted fraction by reverse osmosis.

3 . The method of claim 1 wherein the salt-enriched fraction is heated to volatilize PFAS and then condensing the volatilized PFAS to form a solution of recovered PFAS, wherein the recovered PFAS constitutes the first fraction, and then subjecting the recovered PFAS to SCWO.

4 . The method of claim 1 wherein the salt-depleted fraction is heated by heat exchange with effluent from a SCWO reactor.

5 . The method of claim 4 wherein the salt-depleted fraction is heated to at least 300° C. by heat exchange with effluent from a SCWO reactor and is then further heated in a secondary heat exchange step to a temperature that is at least 100° C. higher than the highest temperature of the heat exchange step.

6 . The method of claim 1 wherein the salt-depleted fraction is heated to a temperature of at least 500 prior to mixing in a mixing tee to form the hot PFAS-containing aqueous mixture prior to SCWO.

7 . (canceled)

8 . The method of claim 1 wherein the salt-depleted effluent is passed into a heat exchanger for heating the salt-depleted fraction.

9 . The method of claim 1 wherein salt-depleted effluent from the SCWO comprises 1 ppm or less or 100 ppt or less or 5 ppt or less PFAS.

10 . (canceled)

11 . The method of claim 1 wherein the SCWO reactor comprises a pipe having interior walls coated with a coating that resists corrosion by HF.

12 . The method of claim 1 wherein salt is removed from the PFAS-containing aqueous mixture or removed from salt-enriched portion by spraying the aqueous mixture or salt-enriched portion through a nozzle wherein a solid salt forms on the nozzle.

13 . The method of claim 1 wherein the SCWO reactor comprises a pipe, and adding a fuel to the mixture that passes through the SCWO reactor to provide heat within the reactor so that no external additional heating for the SCWO reactor is required.

14 . The method of claim 1 wherein the PFAS-containing aqueous mixture is preconcentrated by passing microbubbles through the aqueous mixture and collecting a fraction of PFAS-enriched water from the top of the mixture.

15 - 16 . (canceled)

17 . A method of destroying PFAS in a PFAS-containing aqueous mixture, comprising: separating the PFAS-containing aqueous mixture is separated into a first salt-enriched fraction and a salt-depleted fraction by reverse osmosis; heating the salt-enriched fraction is heated to volatilize PFAS and then condensing the volatilized PFAS to form a solution of recovered PFAS; and reacting the recovered PFAS with an aqueous oxidant under supercritical conditions.

18 . (canceled)

19 . The method of claim 1 wherein, prior to reacting PFAS with an aqueous oxidant, the PFAS-containing aqueous mixture comprises at least 100 ppm PFOA and the method decreases the PFOA concentration by at least 10 6 or 10 7 or 10 8 .

20 - 22 . (canceled)

23 . The method of claim 1 wherein the PFAS-containing aqueous mixture comprises 0.5 to 5 or 1 to 3 or about 2 wt % organic fuel.

24 - 26 . (canceled)

27 . The method of claim 1 wherein no external heating for the SCWO step is required after start-up.

28 . The method of claim 17 wherein the PFAS-containing aqueous mixture comprises at least 100 ppm PFOA and the method decreases the PFOA concentration by at least 10 6 or 10 7 or 10 8 , and in some embodiments up to about 10 9 .

29 - 30 . (canceled)

31 . The method of claim 1 wherein the PFAS-containing aqueous mixture is a solids-containing mixture comprising at least 5% or at least 10 wt % solids or at least 15 wt % solids.

32 . The method of claim 31 conducted in a transpiring wall reactor with a curved floor or ceiling.

33 - 35 . (canceled)

36 . A system for destroying PFAS, comprising:
a first inlet conduit for passing a PFAS-containing aqueous stream into a mixing joint; a second inlet conduit for passing a heated stream of clean water into the mixing stream; a conduit connecting the mixing tee to an inlet of a SCWO reactor; an outlet of the SCWO reactor connected to a salt separator; the salt separator comprising an effluent outlet: configured to pass clean water to a heat exchanger that is configured to heat clean water that leaves the heat exchanger and enters the mixing tee, or configured to pass the effluent into the mixing tee.

Assignees

• Battelle Memorial Institute

Inventors

• Dejarme Lindy E
• Dasu Kavitha
• Sirabian Russel R
• Dindal Amy
• Ellis Jeffrey
• Heintz Amy
• Garbark Dan
• Bryant Nathan
• Tallarico John
• Casciano Joseph
• Winecki Slawomir
• Holley David
• James Joshua
• Brown Keith
• Hendry Doug
• Argumedo Darwin
• Frank Aaron

Classifications

• C02F1/72 Primary

  by oxidation {(C02F1/4672 takes precedence)} · CPC title

• C02F1/722

  Oxidation by peroxides · CPC title

• C02F2301/066

  Overpressure, high pressure · CPC title

• C02F2201/002

  Construction details of the apparatus · CPC title

• C02F1/78

  with ozone {(C02F1/4672 takes precedence)} · CPC title