Method for removing per- and polyfluoroalkyl substances (PFAS) from waste water
Disclosed is a method for enhancing the removal of a per- and polyfluoroalkyl substances (PFAS) component from waste water using a cationic polymer (e.g., a cationic polymer flocculant or coagulant). The cationic polymer enables gas that is diffused through the waste water to carry at least a portion of the PFAS component to the surface of water, creating a foam that can then be removed.
1. A method for treating waste water to enhance the removal of a per- and polyfluoroalkyl substances (PFAS) component from waste water, the method comprising:
a) contacting the waste water comprising water and the PFAS component with a cationic polymer, wherein the cationic polymer comprises at least one of a polyacrylamide, a polyacrylic acid, a polydiallyldimethyl ammonium, or a polyamine;
b) bubbling a gas through the waste water to form a foam on the surface of the waste water comprising the gas and at least some of the PFAS component; and
c) removing at least some of the foam off the surface of the waste water, thereby removing at least some of the PFAS component from the waste water to form a lower PFAS component content waste water;
wherein the method steps a-c all take place in the same vessel.
2. The method of claim 1 , wherein the waste water comprises a leachate, landfill liquid, condensate, or gas well liquid.
3. The method of claim 1 , wherein the waste water comprises a landfill leachate.
4. The method of claim 1 , wherein the waste water comprises organics having a chemical oxygen demand (COD) of from 500 to 80,000 mg/L.
5. The method of claim 1 , wherein the waste water comprises from 1,000 to 15,000 mg/L total dissolved solids (TDS).
6. The method of claim 1 , wherein the waste water comprises from 50 to 3,000 mg/L ammonia as nitrogen.
7. The method of claim 1 , wherein the waste water comprises humic acid and at least one metal.
8. The method of claim 1 , wherein the PFAS component comprises a perfluorosulfonic acid, a perfluorosulfonate, a perfluorocarboxylic acid, a perfluorocarboxylate, or an anionic salt thereof.
9. The method of claim 1 , wherein the PFAS component comprises at least one of perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), or an anionic salt thereof.
10. The method of claim 1 , wherein the PFAS component comprises both PFOA and PFOS or an anionic salt thereof.
11. The method of claim 1 , wherein the waste water comprises from 10 ng/L to 25 mg/L of each PFAS component.
12. The method of claim 1 , wherein the amount of cationic polymer used is from 5 mg/L to 10,000 mg/L.
13. The method of claim 1 , wherein the gas comprises air.
14. The method of claim 1 , wherein the gas comprises ozone.
15. The method of claim 1 , wherein the bubbling a gas is a diffused aeration process.
16. The method of claim 1 , wherein bubbling the gas produces micron sized or larger bubbles.
17. The method of claim 1 , wherein the amount of gas used is from 10 to 1,000 standard cubic feet per minute (SCFM) per 1,000 cubic feet of waste water.
18. The method of claim 1 , wherein the contacting step a and bubbling step b are performed simultaneously in a continuous process.
19. The method of claim 1 , wherein prior to step a or during step a or step b, the pH of the waste water is adjusted to about neutral.
20. The method of claim 1 , wherein the removing step comprises skimming the foam off the surface of the waste water, vacuum collection of the foam, or overflowing the foam into a collection tank.
21. The method of claim 1 , wherein after the removing step, the removed PFAS component is solidified and stored in a landfill or is transported to a deep well site for injection.
22. The method of claim 1 , wherein after the removing step, the lower PFAS component content waste water is discharged to a publicly owned treatment works.
23. The method of claim 1 , wherein the PFAS component comprises PFOA and the removal efficiency of the PFOA is at least 90%.
24. The method of claim 1 , wherein the PFAS component comprises PFOS and the removal efficiency of the PFOS is at least 90%.
25. The method of claim 1 , wherein the method does not further comprise an oxidation treatment of the PFAS component.
26. A method for treating waste water to enhance the removal of a per- and polyfluoroalkyl substances (PFAS) component from waste water, the method consisting essentially of:
a) contacting the waste water comprising water and the PFAS component with a cationic polymer, wherein the cationic polymer comprises at least one of a polyacrylamide, a polyacrylic acid, a polydiallyldimethyl ammonium, or a polyamine;
b) bubbling a gas through the waste water to form a foam on the surface of the waste water comprising the gas and at least some of the PFAS component; and
c) removing at least some of the foam off the surface of the waste water, thereby removing at least some of the PFAS component from the waste water to form a lower PFAS component content waste water.
27. A method for treating waste water to enhance the removal of a per- and polyfluoroalkyl substances (PFAS) component from waste water, the method comprising:
a) contacting the waste water comprising water and the PFAS component with a cationic polymer, wherein the cationic polymer comprises:
i) a polydiallyldimethyl ammonium having the following repeating unit:
wherein X is an anion;
ii) or a polyamine having the following repeating unit:
wherein X is an anion;
b) bubbling a gas through the waste water to form a foam on the surface of the waste water comprising the gas and at least some of the PFAS component; and
c) removing at least some of the foam off the surface of the waste water, thereby removing at least some of the PFAS component from the waste water to form a lower PFAS component content waste water.
28. The method of claim 27 , wherein the method steps a-c all take place in the same vessel.
29. The method of claim 27 , wherein the PFAS component has six to fourteen carbons.
30. The method of claim 29 , wherein the PFAS component is PFHxS, PFHpS, PFOS, PFNS, PFDS, PFDoS, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnDA, PFDoDA, PFTrDA, or an anionic salt thereof.
31. The method of claim 29 , wherein the cationic polymer comprises the polyamine.
32. The method of claim 27 , wherein the PFAS component has four to six carbons.
33. The method of claim 32 , wherein the PFAS component is PFBA, PFBS, PFPeA, PFPeS, PFHxA, or an anionic salt thereof.
34. The method of claim 32 , wherein the cationic polymer comprises the polydiallyldimethyl ammonium.