Removal of selenium in contaminated wastewater streams
Compositions and methods for the removal of selenium species from water containing high-salt concentrations and/or petroleum contaminants are described. The compositions and methods use a selenium-reducing microorganism adapted to adverse environments.
1. A method for removing selenium species from high-salt waters, comprising:
contacting high-salt water having a sodium chloride concentration of 1 M or greater, with at least one selenium-reducing bacteria capable of growing in said high-salt water, in the presence of dissolved hydrogen and an organic carbon source, said contacting forming a reduced selenium species, and
separating the high-salt water from the reduced selenium species.
2. The method of claim 1 , wherein the bacteria is selected by:
(a) growing a naturally-occurring selenium-reducing bacteria in water, in the presence of dissolved hydrogen and an organic carbon source, to form a biofilm comprising said bacteria,
(b) iteratively increasing the sodium chloride concentration of the water to at least 1 M, while maintaining a biofilm comprised of the bacteria that grow under such conditions, and washing non-salt-tolerant bacteria away from said biofilm, and
(c) recovering the selenium-reducing bacteria that grow under high-salt conditions of 1 M or greater sodium chloride concentration.
3. The method of claim 2 , wherein the bacteria reduce selenate.
4. The method of claim 2 , wherein the bacteria reduce selenite.
5. The method of claim 2 , wherein the bacteria reduce selenate and selenite to Se°.
6. The method of claim 1 , wherein the dissolved hydrogen is from hydrogen gas sparged into the water.
7. The method of claim 1 , performed in a bioreactor comprising a plurality of hollow filaments, wherein the bacteria form a biofilm on an exterior surface of the hollow filaments and hydrogen gas is introduced to an interior lumen of the hollow filaments.
8. The method of claim 7 , wherein the filaments are comprised of a polymer selected from polyester, polyethylene, and polypropylene.
9. A method for selecting a selenium-reducing, high-salt-tolerant microorganism, comprising:
(a) growing a naturally-occurring selenium-reducing bacteria in water, in the presence of dissolved hydrogen and an organic carbon source, to form a biofilm comprising said bacteria,
(b) iteratively increasing the sodium chloride concentration of the water to at least 1 M, while maintaining a biofilm comprising bacteria that grow under such conditions, and washing non-salt-tolerant bacteria away from said biofilm, and
(c) recovering the selenium-reducing bacteria that grow in a water having high-salt conditions of 1 M or greater sodium chloride concentration.
10. The method of claim 9 , wherein the bacteria reduce selenate.
11. The method of claim 9 , wherein the bacteria reduce selenite.
12. The method of claim 9 , wherein the bacteria reduce selenate and selenite to Se°.
13. The method of claim 9 , wherein the dissolved hydrogen is from hydrogen gas sparged into the water.
14. The method of claim 9 , performed in a bioreactor comprising a plurality of hollow filaments, wherein the bacteria form a film on the outside of the filaments and hydrogen gas is introduced inside the hollow filaments.
15. The method of claim 14 , wherein the filaments are comprised of a polymer selected from polyester, polyethylene, and polypropylene.
16. Selenium-reducing, high-salt-tolerant bacteria produced by the method of claim 9 .
17. A business method, comprising:
obtaining high-salt wastewater from a customer, said high-salt wastewater having a sodium chloride concentration of 1 M or greater,
removing selenium from the wastewater by contacting said wastewater with selenium-reducing, high-salt tolerant bacteria, in the presence of dissolved hydrogen and an organic carbon source, said contacting forming a reduced selenium species,
separating high-salt water from the reduced selenium species,
returning high-salt, selenium-depleted water to the customer for reuse, and
charging the customer a price.
18. The business method of claim 17 , further including desalinating the high-salt, selenium-depleted water.
19. The business method of claim 17 , wherein the selenium-reducing, high-salt tolerant bacteria are obtained by
(a) growing a naturally-occurring selenium-reducing bacteria in water, in the presence of dissolved hydrogen and an organic carbon source, to form a biofilm comprising said bacteria,
(b) iteratively increasing the sodium chloride concentration of the water to at least 1 M, while maintaining a biofilm comprising bacteria capable of growing under such conditions, and washing non-salt-tolerant bacteria away from said biofilm, and
(c) recovering the selenium-reducing bacteria that grow under high-salt conditions of 1 M or greater sodium chloride concentration.
20. A method for removing selenium species from petroleum-contaminated water, comprising
contacting petroleum-contaminated water with at least one selenium-reducing bacteria capable of growing in petroleum-contaminated water, in the presence of dissolved hydrogen and an organic carbon source, said contacting forming a reduced selenium species, and
separating the water from the reduced selenium species
wherein the bacteria is selected by:
(a) growing a naturally-occurring selenium-reducing bacteria in water, in the presence of dissolved hydrogen and an organic carbon source, to form a biofilm comprising said bacteria,
(b) iteratively increasing the amount of at least one petroleum contaminant in the water, while maintaining a biofilm comprising bacteria that grow under such conditions of petroleum contamination, and washing non-petroleum-tolerant bacteria away from said biofilm, and
(c) recovering the selenium-reducing bacteria that grow under such conditions of petroleum contamination.
21. A method for selecting a selenium-reducing, petroleum contaminant-tolerant microorganism, comprising:
(a) growing a naturally-occurring selenium-reducing bacteria in water, in the presence of dissolved hydrogen and an organic carbon source, to form a biofilm comprising said bacteria,
(b) iteratively increasing the amount of at least one petroleum contaminant in the water, while maintaining a biofilm comprising bacteria that grow under such conditions of petroleum contamination, and washing non-petroleum-tolerant bacteria away from said biofilm, and
(c) recovering the selenium-reducing bacteria that grow under such conditions of petroleum contamination.
22. The method of claim 21 , wherein the bacteria reduce selenate.
23. The method of claim 21 , wherein the bacteria reduce selenite.
24. The method of claim 21 , wherein the bacteria reduce selenate and selenite to Se°.
25. The method of claim 21 , wherein the dissolved hydrogen is from hydrogen gas sparged into the water.
26. The method of claim 21 , performed in a bioreactor comprising a plurality of hollow filaments, wherein the bacteria form a film on the outside of the filaments and hydrogen gas is introduced inside the hollow filaments.
27. The method of claim 26 , wherein the filaments are comprised of a polymer selected from polyester, polyethylene, and polypropylene.
28. Selenium-reducing, petroleum contamination-tolerant bacteria produced by the method of claim 21 .
29. A business method, comprising:
obtaining petroleum-contaminated wastewater from a customer,
removing selenium from the wastewater using selenium-reducing, petroleum contamination tolerant bacteria,
returning petroleum-contaminated, selenium-depleted water to the customer for reuse, and
charging the customer a price;
wherein the selenium-reducing, petroleum contamination tolerant bacteria are obtained by:
(a) growing a naturally-occurring selenium-reducing bacteria in water, in the presence of dissolved hydrogen and an organic carbon source, to form a biofilm comprising said bacteria,
(b) iteratively increasing the amount of at least one petroleum contaminant in the water, while maintaining a biofilm comprising bacteria that grow under such conditions of petroleum contamination, and washing non-petroleum-tolerant bacteria away from said biofilm, and
(c) recovering the selenium-reducing bacteria that grow under such conditions of petroleum contamination.