Granted Patent B1

US 7,588,744 · App. 12/474,027 · Granted Sep 15, 2009

Abstract

Claims (14)

1. A method for recovering phosphorus desorbed from an influent solution to an adsorptive medium, resulting in a spent medium, the method comprising

contacting the phosphorus containing spent medium with a solution of potassium hydroxide to form a first effluent; and

contacting the first effluent with a solution of nitric acid to form a second effluent, the second effluent containing phosphorus, potassium, and nitrogen.

2. The method of claim 1 wherein the spent sorbent is a metal oxide adsorbent, an ion-exchange adsorbent, or a hybrid adsorbent.

3. The method of claim 1 wherein said phosphorus comprises a phosphate.

4. The method of claim 1 wherein said phosphorus comprises at least one member selected from the group consisting of an orthophosphate anion, a polyphosphate anion, an acid of an orthophosphate anion, and an acid of a polyphosphate anion.

5. The method of claim 1 wherein the second effluent includes potassium, nitrate, and phosphate ions.

6. The method of claim 5 further comprising the step of separating the potassium nitrate and the potassium phosphate from the second effluent.

7. The method of claim 1 wherein the medium comprises a plurality of beads.

8. The method of claim 1 further comprising the step of applying the second effluent as a fertilizer.

9. The method of claim 1 wherein the ratio of nitrogen:phosphorus:potassium in the second effluent is adjusted.

10. The method of claim 1 wherein the second effluent is adjusted to increase the concentration of at least one member selected from the group consisting of nitrogen, phosphorus, and potassium.

11. The method of claim 1 wherein the concentration of potassium hydroxide ranges from about 0.1% to about 10%.

12. The method of claim 1 wherein the concentration of nitric acid ranges from about 1% to about 70%.

Assignments (10)