Method of Reducing Carbon Dioxide and Metal-Containing Dust

Abstract

The invention relates to a method of reducing carbon dioxide and metal-containing dust and, more particularly, to a method of simultaneously reducing carbon dioxide and metal-containing dust by passing an off-gas, which contains carbon dioxide or carbon dioxide and metal-containing dust, through a reactor in which a sulfur-oxidizing microorganism is grown using carbon dioxide as a carbon source to produce sulfuric acid, and producing metal sulfates (MeSO.sub.4) by reaction of the produced sulfur acid with metal components present in the off-gas.

Claims

1. A method of reducing carbon dioxide and metal-containing dust, the method comprising: removing the carbon dioxide and metal-containing dust present in off-gas by passing the off-gas which contains carbon dioxide and metal-containing dust through reactor containing sulfur-oxidizing microorganisms.

2. The method of reducing carbon dioxide and metal-containing dust of claim 1, wherein the sulfur-oxidizing microorganisms produce sulfuric acid by oxidizing sulfur using carbon as a carbon source, and the sulfuric acid produced reacts with the metal contained in the dust to produce metal sulfate.

3. The method of reducing carbon dioxide and metal-containing dust of claim 1, wherein the metal is one or more selected from the group consisting of Mg Ca, V, Cr, Mn, Co, Ni, Zn, Cu, Na, K, Fe, Cd. Sn, Pb, Nb, Mo, Ru, V, Ga, Sr, Ba, Ti, Zr and Sr.

4. The method of reducing carbon dioxide and metal-containing dust of claim 1, wherein the sulfur-oxidizing microorganism is one or more selected from the group consisting of Acidianus, Aquifex, Hydrogenobacter, Thiobacillus, Thiomicrospira, Sulfurimonas, Halothiobacillus, Acidithiobacillus and Thermithiobacillus.

5. The method of reducing carbon dioxide and metal-containing dust of claim 1, wherein the off-gas contains carbon dioxide or carbon dioxide and metal-containing dust.

6. A method of reducing metal-containing dust, the method comprising: oxidizing sulfur or a sulfur-containing compound into sulfuric acid using sulfur-oxidizing microorganisms; and producing metal sulfates by reacting the sulfuric acid with the metal present in the metal-containing dust.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a view schematically showing a process of treating carbon dioxide and metal-containing dust according to one embodiment of the present invention.

[0009] FIG. 2 depicts images showing the number of microbial cells before culture (a) according to one embodiment of the present and the number of microbial cells after culture (b).

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] Unless otherwise defined, all the technical and scientific terms used in the present specification have the same meanings as commonly understood by those skilled in the art to which the present disclosure belongs. In general, the nomenclature used in the present specification is well known and commonly used in the art.

[0011] The present invention relates to technology for converting carbon dioxide and reducing metal-containing dust. As shown in FIG. 1, it has been found that when an off-gas and/or fine gas containing carbon dioxide and metal-containing dust is passed directly through a microbial incubator, the microorganism in the microbial incubator produces sulfuric acid (H.sub.2SO.sub.4) while growing using the energy obtained through oxidation of sulfur, and uses the carbon dioxide contained in the off-gas as a carbon source, and the metals in the dust are used as pH neutralizers. According to this principle, an effect of simultaneously reducing the carbon dioxide and the metal-containing dust is obtained.

[0012] Therefore, one aspect of the present invention is directed to a method of reducing carbon dioxide and metal-containing dust, the method including a step of passing an off-gas, which contains carbon dioxide and metal-containing dust, through a sulfur-oxidizing microorganism reactor, thereby removing the carbon dioxide and metal-containing dust present in the off-gas.

[0013] Another aspect of the present invention is directed to a method of reducing carbon dioxide, the method including a step of culturing a sulfur-oxidizing microorganism by passing carbon dioxide through a sulfur-oxidizing microorganism reactor.

[0014] Still another aspect of the present invention is directed to a method of reducing sulfur, the method including a step of oxidizing sulfur or a sulfur-containing compound into sulfuric acid using a sulfur-oxidizing microorganism.

[0015] Yet another aspect of the present invention is directed to a method of reducing metal-containing dust, the method including the steps of: oxidizing sulfur or a sulfur-containing compound into sulfuric acid using a sulfur-oxidizing microorganism; and reacting the sulfuric acid with metals present in the metal-containing dust to produce metal sulfates.

[0016] According to the present invention, when the off-gas is passed through the sulfuric-acid-producing microorganism reactor, the sulfur in the off-gas is oxidized using the carbon dioxide as a carbon source to produce sulfuric acid. The produced sulfuric acid is allowed to react with the metal components or metal oxides (MeO) present in the metal-containing dust to produce metal sulfates (MeSO.sub.4) while the microorganism grows.

[0017] The present invention is a method of treating and removing the metal components in the metal-containing dust with sulfuric acid produced while the carbon dioxide in the off-gas is converted into biomass by a biological method. This method is capable of removing metals present in the metal-containing dust using the produced sulfuric acid while converting the carbon dioxide using the sulfur-oxidizing microorganism. That is, the sulfuric acid may be produced by passing the off-gas through the microorganism reactor containing a sulfur-containing medium and allowing the microorganism to oxidize the sulfur using the carbon dioxide contained in the off-gas as a carbon source (see Reaction Formula 1 below).

Me/MeO+H.sub.2SO.sub.4.fwdarw.MeSO.sub.4+H.sub.2O[Reaction Formula 1]

[0018] (Me: Mg Ca, V, Cr, Mn, Co, Ni, Zn, Cu, Na, K, Fe, Cd, Sn, Pb, Nb, Mo, Ru, V, Ga, Sr, Ba, Ti, Zr, Sr)

[0019] In the present invention, the metal or the metal in the metal oxide may be Mg Ca, V, Cr, Mn, Co, Ni, Zn, Cu, Na, K, Fe, Cd, Sn, Pb, Nb, Mo, Ru, V, Ga, Sr, Ba, Ti, Zr or Sr, and any metal may be used without limitation, as long as it may produce sulfate by reaction with sulfuric acid.

[0020] As used herein, the term sulfur-oxidizing microorganism reactor or sulfuric-acid-producing microorganism reactor refers to a reactor in which the sulfur-oxidizing microorganism selectively uses carbon dioxide as a carbon source and is cultured in sulfur-containing medium.

[0021] In the present invention, the sulfur-oxidizing microorganism may be one or more selected from the group consisting of Acidianus, Aquifex, Hydrogenobacter, Thiobacillus, Thiomicrospira, Sulfurimonas, Halothiobacillus, Acidithiobacillus and Thermithiobacillus.

[0022] In the present invention, a more specific example of the microorganism may be:

[0023] A. Acidianus ambivalens or Acidianus brierleyi;

[0024] B. Aquifex pyrophilus;

[0025] C. Hydrogenobacter acidophilus, Hydrogenobacter thermophiles;

[0026] D. Thiobacillus denitrificans;

[0027] E. Thiomicrospira crunogena;

[0028] F. Sulfurimonas autotrophica, Sulfurimonas denitrificans, Sulfurimonas gotlandica or Sulfurimonas paralvinellae;

[0029] G. Halothiobacillus halophilus, Halothiobacillus hydrothermalis, Halothiobacillus kellyi or Halothiobacillus neapolitanus; or

[0030] H. Acidithiobacillus albertensis, Acidithiobacillus caldus, Acidithiobacillus cuprithermicus, Acidithiobacillus ferridurans, Acidithiobacillus ferrivorans, Acidithiobacillus ferrooxidans or Acidithiobacillus thiooxidans.

[0031] In the present invention, the off-gas may be generated in processes of power plants, petroleum plants, waste combustion plants or steel mills, and may additionally contain atmospheric fine dust.

EXAMPLES

[0032] Hereinafter, the present invention will be described in more detail with reference to examples. It will be obvious to skilled in the art that these examples are merely to illustrate the present invention, and the scope of the present invention is not limited by these examples.

Example 1

[0033] 1. Pre-Culture of Sulfur-Oxidizing Microorganism

[0034] In a reactor equipped with a CO.sub.2 chamber, 50 ml of a medium containing 0.2 g/L (NH.sub.4).sub.2SO.sub.4, 0.5 g/L MgSO.sub.4.7H.sub.2O, 250 mg/L CaCl.sub.2.2H.sub.2O, 3 g/L KH.sub.2PO.sub.4, 10 mg/L FeSO.sub.4.7H.sub.2O and 10 g/L sulfur powder was placed in a 100-ml flask and inoculated with 1 ml of a sulfur-oxidizing microorganism. The microorganism was cultured under the conditions of culture temperature of 30 C. and stirring speed of 150 rpm for 7 days. Then, 200 ml of a medium containing the same components as described above was placed in a 1 L flask, and 2% of the culture was inoculated in the medium, cultured for 7 days, and then used for main culture inoculation.

[0035] 2. Main Culture of Sulfur-Oxidizing Microorganism

[0036] Test group: In a reactor equipped with a CO.sub.2 chamber, fly ash was added to a medium (containing 0.2 g/L (NH.sub.4).sub.2SO.sub.4, 3 g/L KH.sub.2PO.sub.4 and 10 g/L sulfur powder) at a concentration of 875 mg/L, and then 10% of the pre-cultured culture was inoculated into the medium. At this time, the pH was 2.15. The pH after 8 days of culture under conditions of 30 C. and 150 rpm was 1.20. The reason why the initial pH was low is because of the inoculated culture, and the reason why the pH decreased after culturing is because the sulfur-oxidizing microorganism produced sulfuric acid while growing (see FIG. 2).

[0037] FIGS. 2(a) and 2(b) show the number of microbial cells before culture of the sulfur-oxidizing microorganism in comparison with the number of microbial cells after culture.

[0038] Control group: fly ash was added to a medium (containing 10 g/L sulfur powder) at a concentration of 875 mg/L, followed by 8 days of culture under conditions of 30 C. and 150 rpm. The initial pH was 11.0, and the pH after 8 days of culture was 7.63. The reason why the pH decreased is believed to be because carbonate was produced due to CO.sub.2 in the air.

[0039] As shown in Table 1 below, the content of metal components in the culture medium of the test group was higher than in the control group shown in Table 2 below. From this, it can be seen that the metals in the fly ash were leached out by the sulfuric acid produced while the sulfur-oxidizing microorganism grew using carbon dioxide as a carbon source. Table 3 below showing the results of analyzing the content of metal components in the fly ash used in the experiment.

TABLE-US-00001 TABLE 1 Metal content in culture medium of test group elements Al Ca Fe Mg Na Ba Sr Ti Mn Sample name Content Content Content Content Content Content Content Content Content Before 3.8 56.9 2.1 6.2 18.4 0.1 0.4 0.1 0.3 culture of test group After culture 13.4 72.2 7.4 8.2 18.9 0.1 0.6 0.3 0.5 of test group

TABLE-US-00002 TABLE 1 Metal content in culture medium of control group elements Al Ca Fe Mg Na Ba Sr Ti Mn Sample name Content Content Content Content Content Content Content Content Content Before 0.5 17.5 0.1 0.3 1.0 N/D N/D N/D N/D culture of control group After culture 0.3 50.7 N/D 1.6 1.0 0.1 0.3 N/D N/D of control group

TABLE-US-00003 TABLE 3 Metal content in fly ash elements Al Ca Fe Mg Na Ba Sr Ti Mn Sample name Content Content Content Content Content Content Content Content Content Fly ash 5.5 8.5 3.3 5680 4820 730 940 2170 910 wt % wt % wt %

[0040] From the results of the Examples above, it was confirmed that when the off-gas containing carbon dioxide and metal-containing dust was passed through the sulfur-oxidizing microorganism reactor, the carbon dioxide could be removed using the sulfur-oxidizing microorganism, and the same time, metals in the metal-containing dust could be removed using the produced sulfuric acid.

INDUSTRIAL APPLICABILITY

[0041] The method of reducing carbon dioxide and metal-containing dust according to the present invention has the effect of simultaneously reducing carbon dioxide and metal-containing dust according to the principle by which CO.sub.2 contained in the off-gas is used as a carbon source and the metals present in the dust are used as pH neutralizers and nutrient sources.

[0042] Although the present invention has been described in detail with reference to the specific features, it will be apparent to those skilled in the art that this description is only of a preferred embodiment thereof, and does not limit the scope of the present invention. Thus, the substantial scope of the present invention will be defined by the appended claims and equivalents thereof.