Sodium nitrite oxidation of hydrogen sulfide

1. A method for treating hydrogen sulfide in a solution, comprising:

(A) adding sodium nitrite to the solution;

(B) allowing the sodium nitrite to treat at least a portion of the hydrogen sulfide in the solution for at least two hours to provide a partially-treated solution comprising a pH level above 9.0;

(C) lowering and maintaining the pH level of the partially-treated solution to a desired range by periodically adding a pH buffer in any amount to the partially-treated solution, wherein lowering and maintaining the pH level to the desired range allows the sodium nitrite to continue treating the hydrogen sulfide in the partially-treated solution to completion.

2. The method of claim 1 , wherein lowering the pH level of the partially-treated solution causes any free ammonia in the partially-treated solution to be present only as an ammonium salt.

3. The method of claim 2 , further comprising introducing an ammonia-removal gas onto the partially-treated solution to remove the ammonium salt.

4. The method of claim 3 , wherein the ammonia-removal gas is nitrogen.

5. The method of claim 3 , wherein the ammonia-removal gas is air.

6. The method of claim 1 , wherein the adding of the pH buffer occurs about every hour for about a three hour segment of time.

7. The method of claim 1 , wherein the periodic adding of the pH buffer occurs in adjusted amounts.

8. The method of claim 1 , wherein the concentration of the hydrogen sulfide in the solution is up to about 25,000 mg/liter.

9. The method of claim 1 , wherein the sodium nitrite is added at a mole ratio to the hydrogen sulfide from about 1:3 to about 2:3.

10. The method of claim 1 , wherein the sodium nitrite is added at a weight ratio to the hydrogen sulfide from about 0.676:1 to about 5:1.

11. The method of claim 1 , wherein steps (A)-(C) occur at a temperature between about ambient temperature and about a boiling temperature of the solution.

12. The method of claim 1 , wherein step (A)-(C) occur at a temperature between about 40° C. and about 70° C.

13. The method of claim 1 , wherein step (A)-(C) occur at a temperature of about 45° C.

14. The method of claim 1 , wherein the treating of the hydrogen sulfide in the partially-treated solution to completion takes between about 0 hours and about 7 hours.

15. The method of claim 1 , wherein the solution is disposed in a vessel.

16. The method of claim 1 , wherein step (C) maintains the pH level to between about 7.0 to about 9.0.

17. The method of claim 1 , wherein the pH buffer comprises citric acid.

18. The method of claim 1 , wherein the pH buffer comprises phosphoric acid.