Method 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 said oxygen-comprising gas when entering said treatment zone to available sulfide in said anaerobic aqueous solution when entering said treatment zone is at least approximately 1.5 and less than approximately 3.0; and/or
said one or more selected nitrates and/or nitrites, when within said treatment zone, comprises a concentration of nitrate in a range of approximately 3.5 M to approximately 4.5 M.
2. The method of claim 1 , further comprising:
introducing said one or more selected ferric/ferrous chelates into said treatment zone.
3. The method of claim 1 , further comprising:
mixing said one or more selected ferric/ferrous chelates with said anaerobic aqueous solution.
4. The method of claim 1 , further comprising:
introducing said anaerobic aqueous solution into said treatment zone.
5. The method of claim 1 , further comprising:
flowing said anaerobic aqueous solution through said treatment zone.
6. The method of claim 1 , further comprising:
injecting said oxygen-comprising gas into said anaerobic aqueous solution.
7. The method of claim 1 , further comprising:
diffusing said oxygen-comprising gas into said anaerobic aqueous solution.
8. The method of claim 1 , further comprising:
contacting said oxygen-comprising gas with said anaerobic aqueous solution for at least approximately 3 minutes in said treatment zone.
9. The method of claim 1 , further comprising:
introducing said one or more selected nitrates and/or nitrites into said treatment zone during said reacting.
10. The method of claim 1 , further comprising:
introducing said one or more selected nitrates and/or nitrites into said treatment zone during said reacting, said 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 said one or more nitrates and/or nitrites with said anaerobic aqueous solution.
12. The method of claim 1 , further comprising:
oxidizing any of said 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 said 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 said treatment zone, initiating a repeating oxidation-reduction cycle that comprises:
oxidizing any of said one or more selected ferric/ferrous chelates that are in a ferrous state to a ferric state; and
reducing any of said 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 said reacting, converting available sulfides in said anaerobic aqueous solution to sulfur oxides.
16. The method of claim 1 , wherein:
said one or more selected ferric/ferrous chelates are one or more ferro aminocarboxylates.
17. The method of claim 1 , wherein:
said 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:
said one or more selected ferric/ferrous chelates is ferric/ferrous MGDA.
19. The method of claim 1 , wherein:
said one or more selected ferric/ferrous chelates is ferric/ferrous gluconate.
20. The method of claim 1 , wherein:
said one or more selected ferric/ferrous chelates, when within said treatment zone, comprises a concentration of ferric/ferrous chelate in a range of approximately 0.05 M to approximately 1.0 M.
21. The method of claim 1 , wherein:
said anaerobic aqueous solution comprises an oxidant.
22. The method of claim 1 , wherein:
a pH of said anaerobic aqueous solution when prior to entering said treatment zone is within a range of approximately 6.0 to approximately 8.5.
23. The method of claim 1 , wherein:
said oxygen-comprising gas is substantially pure oxygen.
24. The method of claim 1 , wherein:
said oxygen-comprising gas is compressed air.
25. The method of claim 1 , wherein:
a mass-to-mass ratio of oxygen in said oxygen-comprising gas when entering said treatment zone to available sulfide in said anaerobic aqueous solution when entering said treatment zone is less than approximately 2.0.