Methods of recovering platinum group metals from waste streams

Patent metadata

Field	Value
Publication number	US-11459253-B2
Application number	US-201716074719-A
Country	US
Kind code	B2
Filing date	Feb 2, 2017
Priority date	Feb 3, 2016
Publication date	Oct 4, 2022
Grant date	Oct 4, 2022

Abstract

The present invention relates to systems and methods for removing and recovering precious metals, such as platinum-group metals (PGMs), including palladium, from wastewater and waste streams. The invention also relates to systems and methods for recycling the recovered precious metals for catalytic applications.

First claim

What is claimed:

1. A method of removing platinum-group metal contaminants from a fluid and harvesting a platinum-group metal from the platinum-group metal contaminants, the method comprising:
contacting a fluid containing a platinum-group metal contaminant to a hydrogen gas and a biofilm anchored to a membrane, the biofilm anchored to the membrane comprising a hydrogen-oxidizing microorganism, an acidophilic microorganism, and a microorganism that reduces platinum-group metals;
capturing the platinum-group metal contaminant in the biofilm; and
harvesting the platinum-group metal contaminant from the biofilm.

2. The method of claim 1 , the method further comprising:
providing an aqueous system, wherein the aqueous system comprises the membrane and the membrane is a hollow fiber membrane;
inoculating the hollow fiber membrane with sludge to establish a biofilm-forming population of microorganisms on the hollow fiber membrane, wherein the biofilm-forming population of microorganisms forms the biofilm anchored to the membrane;
providing the inoculated aqueous system with a fluid comprising platinum-group metal contaminants, wherein the fluid comprising platinum-group metal contaminants establishes the biofilm and supports the growth of the biofilm.

3. The method of claim 2 , wherein the aqueous system is an anaerobic aqueous system.

4. The method of claim 1 , wherein the fluid comprising platinum-group metal contaminants comprises a nitrogen source selected from the group consisting of a nitrate salt (NO 3 − ) and a nitrite salt (NO 2 ).

5. The method of claim 1 , the method further comprising:
providing the inoculated aqueous system with a denitrifying medium until the biofilm-forming population of microorganisms forms the biofilm, wherein the denitrifying medium comprises a nitrogen source selected from the group consisting of a nitrate salt (NO 3 − ) and a nitrite salt (NO 2 − ).

6. The method of claim 1 , wherein the biofilm comprises a genus of microorganism that is hydrogen-oxidizing, acidophilic, and reduces platinum-group metals.

7. The method of claim 1 , wherein the reduced platinum-group metal contaminant is in the form of a nanoparticle.

8. The method of claim 1 , wherein the platinum-group metal contaminant is palladium (II) (Pd(II)), the biofilm comprises a microorganism that reduces Pd (II), and the reduced platinum-group metal contaminant is solid palladium (0) (Pd(0)).

9. The method of claim 1 , wherein the fluid comprising platinum-group metal contaminants has a pH range selected from the ranges in the group consisting of: 3-8, less than 7, and 3-5.

10. The method of claim 1 , wherein the biofilm comprises at least one microorganism population selected from the group consisting of: Methanobacteriales, Actinomycetales, Clostridiales, Bacteroidales, Flavobacteriales, Rhizobiales, Rhodospirillales, Burkholderiales, Rhodocyclales, Xanthomonadales, and Desulfovibrionales.

11. The method of claim 1 , wherein the biofilm comprises at least one microorganism population selected from the group consisting of: Rhodocyclaceae, Rhizobiales, Burkholderiales, Methanobacteriaceae, Mycobacteriaceae, Comamonadaceae, Bradyrhizobiaceae, Desulfovibrionaceae, and Xanthomonadaceae.

12. The method of claim 1 , wherein the biofilm comprises at least one microorganism population selected from the group consisting of: Dechloromonas, Desulfovibrio , and Actinobacteria.

13. The method of claim 1 , wherein the biofilm comprises at least one group of microorganism selected from the group consisting of consisting of: methanobacteria, flavobacteria, α-proteobacteria, β-proteobacteria, and δ-proteobacteria.

14. The method of claim 1 , wherein the reduced platinum-group metal contaminant is in a solid state.

15. A system for removing and harvesting platinum-group metal contaminants from a fluid, the system comprising:
a membrane;
an inoculant comprising a biofilm-forming population of microorganisms comprising a hydrogen oxidizer, an acidophile, and a microorganism that reduces platinum-group metals; and
a hydrogen-gas source.

16. The system of claim 15 , wherein the inoculant comprises at least one group of microorganism selected from the group consisting of: methanobacteria, flavobacteria, α-proteobacteria, β-proteobacteria, and δ-proteobacteria.

17. The system of claim 15 , wherein the fluid comprises a platinum-group metal contaminant and a biofilm comprising the biofilm-forming population of microorganisms utilizes hydrogen gas to reduce the platinum-group metal contaminant, thereby capturing reduced platinum-group metal in the biofilm.

18. The system of claim 15 , wherein the membrane is a nonporous hollow fiber membrane.

19. The system of claim 15 , further comprising a growth medium, the growth medium comprising at least one of a nitrogen source and a nutrient, wherein the nitrogen source is selected from the group consisting of a nitrate salt (NO 3 − ), and a nitrite salt (NO 2 − ), wherein the nutrient comprises at least one selected from the group consisting of: NH 4 C 1 , K 2 HPO 4 , CaCl 2 , MgCl 2 , FeCl 2 , MgSO 4 , ZnSO 4 , MnCl 2 , H 3 BO 3 , CoCl 2 , CuCl 2 , NiCl 2 , Na 2 MoO 4 , and Na 2 SeO 3 .

20. The system of claim 15 , wherein the biofilm-forming population of microorganisms forms a biofilm, wherein the biofilm is anchored to the membrane.

Assignees

• Univ Arizona State

Inventors

• Zhou Chen
• Marcus Andrew
• Rittmann Bruce
• Wang Zhaocheng
• Ontiveros-Valencia Aura
• Krajmalnik-Brown Rosa

Classifications

• C02F2209/40

  Liquid flow rate · CPC title

• C02F3/341

  Consortia of bacteria · CPC title

• C02F2209/30

  H2 · CPC title

• C02F3/2806 Primary

  Anaerobic processes using solid supports for microorganisms · CPC title

• C02F2101/20

  Heavy metals or heavy metal compounds · CPC title