Methods for managing sulfide in wastewater systems
View Patent ↗Certain exemplary embodiments can provide a system, machine, device, manufacture, circuit, composition, and/or user interface adapted for and/or resulting from, and/or a method and/or machine-readable medium comprising machine-implementable instructions for, activities that can comprise and/or relate to, in a treatment zone, reacting an oxygen-comprising gas, one or more selected ferric/ferrous chelates, one or more selected nitrates and/or nitrites, and/or anaerobic wastewater.
1. A method comprising:
in a treatment zone of a manmade container, reacting one or more selected ferric/ferrous chelates, an anaerobic aqueous solution, and an oxygen-comprising gas and/or one or more selected nitrates and/or nitrites,
wherein:
a mass-to-mass ratio of oxygen in the oxygen-comprising gas when entering the treatment zone to available sulfide in the anaerobic aqueous solution when entering the treatment zone is at least approximately 1.5 and less than approximately 3.0; and
when entering the treatment zone, a concentration of the one or more selected ferric/ferrous chelates is in a range of approximately 0.004 M per 1.0 M of sulfide to approximately 0.02 M per 1.0 M of sulfide.
2. The method of claim 1 , further comprising:
introducing the one or more selected ferric/ferrous chelates into the treatment zone.
3. The method of claim 1 , further comprising:
mixing the one or more selected ferric/ferrous chelates with the anaerobic aqueous solution.
4. The method of claim 1 , further comprising:
introducing the anaerobic aqueous solution into the treatment zone.
5. The method of claim 1 , further comprising:
flowing the anaerobic aqueous solution through the treatment zone.
6. The method of claim 1 , further comprising:
injecting the oxygen-comprising gas into the anaerobic aqueous solution.
7. The method of claim 1 , further comprising:
diffusing the oxygen-comprising gas into the anaerobic aqueous solution.
8. The method of claim 1 , further comprising:
contacting the oxygen-comprising gas with the anaerobic aqueous solution for at least approximately 3 minutes in the treatment zone.
9. The method of claim 1 , further comprising:
introducing the one or more selected nitrates and/or nitrites into the treatment zone during the reacting.
10. The method of claim 1 , further comprising:
introducing the one or more selected nitrates and/or nitrites into the treatment zone during the reacting, the one or more selected nitrates and/or nitrites comprising a nitrate salt and/or a nitrite salt.
11. The method of claim 1 , further comprising:
mixing the one or more nitrates and/or nitrites with the anaerobic aqueous solution.
12. The method of claim 1 , further comprising:
oxidizing any of the one or more selected ferric/ferrous chelates that are in a ferrous state to a ferric state.
13. The method of claim 1 , further comprising:
reducing any of the one or more selected ferric/ferrous chelates that are in a ferric state to a ferrous state.
14. The method of claim 1 , further comprising:
within the treatment zone, initiating a repeating oxidation-reduction cycle that comprises:
oxidizing any of the one or more selected ferric/ferrous chelates that are in a ferrous state to a ferric state; and
reducing any of the one or more selected ferric/ferrous chelates that are in a ferric state to a ferrous state.
15. The method of claim 1 , further comprising:
via the reacting, converting available sulfides in the anaerobic aqueous solution to sulfur oxides.
16. The method of claim 1 , wherein:
the one or more selected ferric/ferrous chelates are one or more ferro aminocarboxylates.
17. The method of claim 1 , wherein:
the one or more selected ferric/ferrous chelates are selected from ferric/ferrous MGDA, ferric/ferrous EDTA, ferric/ferrous HEIDA ferric/ferrous NTA, and ferric/ferrous gluconate.
18. The method of claim 1 , wherein:
the one or more selected ferric/ferrous chelates is ferric/ferrous MGDA.
19. The method of claim 1 , wherein:
the one or more selected ferric/ferrous chelates is ferric/ferrous gluconate.
20. The method of claim 1 , wherein:
the one or more selected nitrates and/or nitrites, when within the treatment zone, is maintained at a concentration of nitrate in a molar ratio of approximately 3.5 M to approximately 4.5 M per 1.0 M of sulfide.
21. The method of claim 1 , wherein:
the anaerobic aqueous solution comprises an oxidant.
22. The method of claim 1 , wherein:
a pH of the anaerobic aqueous solution when prior to entering the treatment zone is within a range of approximately 6.0 to approximately 8.5.
23. The method of claim 1 , wherein:
the oxygen-comprising gas is substantially pure oxygen.
24. The method of claim 1 , wherein:
the oxygen-comprising gas is compressed air.
25. The method of claim 1 , wherein:
a mass-to-mass ratio of oxygen in the oxygen-comprising gas when entering the treatment zone to available sulfide in the anaerobic aqueous solution when entering the treatment zone is less than approximately 2.0.
26. The method of claim 1 , wherein:
the one or more selected nitrates and/or nitrites comprises nitrous oxide.
27. The method of claim 1 , wherein:
the nitrate concentration is maintained for at least 3 minutes.
28. The method of claim 1 , wherein:
nitrate concentration is maintained from approximately 3 minutes to approximately 24 hours.
29. The method of claim 1 , wherein:
a concentration of the one or more selected nitrates and/or nitrites, when within the treatment zone, is sufficient to reduce available sulfide in the anaerobic aqueous solution.
30. The method of claim 1 , wherein:
a concentration of the one or more selected nitrates and/or nitrites, when within the treatment zone, is sufficient to biologically destroy at least a portion of available sulfide in the anaerobic aqueous solution.
31. A method comprising:
in a treatment zone of a manmade container, reacting one or more selected ferric/ferrous chelates, an anaerobic aqueous solution, and an oxygen-comprising gas and/or one or more selected nitrates and/or nitrites,
wherein:
a mass-to-mass ratio of oxygen in the oxygen-comprising gas when entering the treatment zone to available sulfide in the anaerobic aqueous solution when entering the treatment zone is at least approximately 1.5 and less than approximately 3.0; and
a concentration of the one or more selected nitrates and/or nitrites, when within the treatment zone, and a concentration of the one or more selected ferric/ferrous chelates when entering the treatment zone, are sufficient to reduce available sulfide in the anaerobic aqueous solution.