Hydrothermal technology for decontamination and mineralization of perfluoro- and polyfluoroalkyl substance (PFAS) in wastes, concentrate solutions, and chemical stockpiles

Patent metadata

Field	Value
Publication number	US-11577111-B2
Application number	US-201916689426-A
Country	US
Kind code	B2
Filing date	Nov 20, 2019
Priority date	Nov 20, 2018
Publication date	Feb 14, 2023
Grant date	Feb 14, 2023

Abstract

Methods and systems for treating a waste substance containing perfluoro- and polyfluoroalkyl substances (PFAS) and mineralizing the PFAS, at least partially. The method includes combining the PFAS with a first amendment in a reactor to create a combination, heating and pressurizing the combination to hydrothermal conditions, and holding the combination at hydrothermal conditions for a holding time sufficient to at least partially mineralize the PFAS to create a treated combination.

First claim

We claim:

1. A method for treating a waste substance containing PFAS, the method comprising:
combining the PFAS with a first amendment, wherein the first amendment is a base selected from one or more of NaOH, Ca(OH) 2 , Na 2 CO 3 , KOH, NH 4 OH, and Mg(OH) 2 , in a reactor to create a combination having a moisture content of at least 10%;
heating and pressurizing the combination in the reactor to a hydrothermal condition wherein the hydrothermal condition comprises a temperature between 200° C. and 700° C. and a pressure between 2 MPa and 50 MPa; and
holding the combination in the hydrothermal condition for a holding time sufficient to at least partially mineralize the PFAS to create a treated combination.

2. The method of claim 1 , wherein the
temperature is about 200° C. to about 374° C.; and
the pressure is about 2 MPa to about 22 MPa.

3. The method of claim 1 , further comprising bringing the combination to a moisture content greater than about 60%.

4. The method of claim 1 , further comprising adjusting the pH of the treated combination.

5. The method of claim 4 , further comprising reducing the pH of the treated combination.

6. The method of claim 1 , wherein the first amendment includes NaOH.

7. The method of claim 1 , wherein the first amendment includes Ca(OH) 2 .

8. The method of claim 1 , wherein the first amendment includes Na 2 CO 3 .

9. The method of claim 1 , wherein the first amendment includes KOH.

10. The method of claim 3 , wherein the moisture content is at least 75% water.

11. The method of claim 1 , wherein the PFAS is combined with a solvent prior to creating the combination.

12. The method of claim 11 , wherein the solvent is methanol and the moisture content is at least 25% water.

13. The method of claim 1 , wherein the first amendment includes NH 4 OH.

14. The method of claim 1 , wherein the first amendment includes Mg(OH) 2 .

15. The method of claim 1 , wherein the waste substance further contains an organic compound.

16. The method of claim 1 , wherein the method is continuous.

17. The method of claim 1 , wherein the method is batched.

18. The method of claim 1 , where in the pressurizing is autogenous.

19. A system for treating a waste substance containing PFAS substances, the system comprising a vessel adapted to: combine the PFAS with a first amendment in the vessel to create a combination, wherein the first amendment is a base selected from one or more of NaOH, Ca(OH) 2 , Na 2 CO 3 , KOH, NH 4 OH, and Mg(OH) 2 , and the combination having a moisture content of at least 10%;
heat the combination in the vessel to a temperature of about 200° C. to about 700° C.;
pressurize the combination in the vessel to a pressure of about 2 MPa to about 50 MPa; and
hold the combination in a heated and pressurized state for a holding time sufficient to at least partially mineralize the PFAS to create a treated combination.

20. The method of claim 1 , wherein the first amendment is NaOH.

Assignees

• Colorado School Of Mines

Inventors

• Strathmann Timothy James
• Higgins Christopher P
• Wu Boran
• Hao Shilai

Classifications

• A62D3/20

  by hydropyrolysis or destructive steam gasification, e.g. using water and heat or supercritical water, to effect chemical change · CPC title

• C02F1/025 Primary

  Thermal hydrolysis · CPC title

• C02F2101/36

  containing halogen · CPC title

• A62D3/37

  by reduction, e.g. hydrogenation · CPC title

• A62D3/35 Primary

  by hydrolysis · CPC title