A method for enhancing carbon fixation of feldspar minerals using composite microorganisms

Abstract

The present invention discloses a method for enhancing carbon fixation in feldspar minerals using composite microorganisms. The feldspar minerals are crushed and slurried, which is then pumped into a carbon fixation bioreactor containing Aspergillus and silicate bacteria. The absorption slurry rises within the reactor's inner guide tube and then flows downwardly back to the bottom of the reactor along the space between the outer side of the guide tube and the inner wall of the reactor. CO2 is pumped into the reactor from the bottom and fully contacts the biofilm and suspended microorganisms. The CO2 dissolves in the absorption slurry and reacts with metal cations dissolved in the feldspar mineral, ultimately converting it into insoluble carbonate precipitates, achieving the purpose of carbon fixation. The method uses feldspar minerals as raw materials for slurrying and CO2 fixation. The raw material is widely available, the absorption rate is relatively fast, and the carbon fixation process is significant. The composite microbial metabolism produces products such as small molecule acids, which accelerate the decomposition of the feldspar minerals and release metal cations into the absorption slurry. Potassium in the feldspar minerals becomes soluble, facilitating subsequent potassium extraction, achieving the dual effects of carbon fixation and potassium release.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial tail gas purification and resource utilization, and specifically relates to a method for enhancing carbon fixation of feldspar minerals by composite microorganisms. Background Art

[0002] As society's demand for fossil fuels continues to increase, carbon dioxide emissions from industrial production processes are rapidly increasing, and the greenhouse effect caused by carbon dioxide has attracted widespread attention. Currently, the main methods commonly used to capture, store, or fix carbon dioxide include absorption and conversion by plants or algae, physical adsorption, air separation / exhaust recycle, and chemical absorption. Chemical absorption separates carbon dioxide from the gas mixture through a chemical reaction between carbon dioxide and an absorbent slurry. This method has attracted considerable attention in practical applications due to its high absorption capacity, good absorption effect, and low cost.

[0003] Existing patent CN109261116A uses zirconyl nitrate as a zirconium source, lithium hydroxide as a lithium source, and carbonate as a precipitant to carry out a precipitation reaction in an ammonia solution. After the reaction, the reaction is filtered or evaporated to remove water, followed by drying and calcination to obtain a lithium zirconate adsorption material. This method is complex to prepare the adsorption material and requires the addition of chemical reagents, which significantly increases the cost. Existing patent CN107902631A uniformly mixes pretreated potassium feldspar powder, carbon powder, and calcium sulfate, then presses them into tablets. After a high-temperature activation reaction under a nitrogen atmosphere, sulfur dioxide is collected. The calcined slag is mineralized with CO2, and the mineralized slag containing calcium carbonate and a water-soluble potassium sulfate fertilizer are separated and obtained. However, this method requires the addition of large amounts of exogenous reagents, significantly increasing the operating costs of the mineralization carbon fixation process. In the natural environment, the decomposition of feldspar minerals produces silicates and metal cations such as calcium and iron. The dissolved metal cations react with carbon dioxide to form insoluble carbonates. However, the carbon fixation process through this pathway is very slow. Developing and operating efficient and cost-controlled carbon sequestration technologies is of great significance to the realization of the dual carbon action plan in the new era. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for enhancing carbon fixation of feldspar minerals by composite microorganisms. The feldspar minerals are pulped and added to a carbon fixation bioreactor to construct a composite microbial system in which suspended and attached growth states coexist. CO2 is blown in from the bottom of the reactor and fully contacts the biofilm and suspended microorganisms. Metal cations such as calcium and iron dissolved in the feldspar minerals are dissolved and react with CO2, and are eventually converted into insoluble carbonate precipitates to achieve the purpose of carbon fixation. After Aspergillus aculeatus and silicate bacteria are added to the reactor, the content of metabolic products such as small molecular acids in the absorption liquid is higher, which accelerates the decomposition of the feldspar minerals and releases metal cations such as potassium into the absorption liquid, thereby enhancing the carbon fixation and potassium release effects.

[0005] The object of the present invention is achieved by comprising the following steps:

[0006] S1. Aspergillus aculeatus is loaded onto a velvet filler, which is then fixed to the fixed frame of the guide inner tube of the carbon fixation bioreactor. Simultaneously, silicate bacteria that have been cultured and proliferated are added to the reactor; feldspar minerals are crushed to a particle size of less than 100 μm, and then uniformly mixed with an absorption liquid in a slurry tank to form an absorption slurry, which is then pumped into the reactor containing Aspergillus aculeatus and silicate bacteria;

[0007] S2 and CO2 are sent into the reactor through the aeration device at the bottom of the carbon fixation bioreactor, fully contacted with the absorption slurry in the guide inner tube and in an upward flow state, and at the same time fully contacted with the biofilm and suspended microorganisms; then the absorption slurry flows downward in the space outside the guide inner tube and inside the reactor to the bottom of the reactor and is discharged. The discharged absorption slurry is transported by a delivery pump, sprayed out from the spiral nozzle at the top of the reactor, and countercurrently contacts with the CO2 escaping from the liquid absorption system in the reactor; CO2 is finally converted into carbonate precipitates and discharged.

[0008] Preferably, the culturing process of the silicate bacteria is to use 0.5% citric acid to wash the root soil of the cotton bud stage, add potassium feldspar powder at a rate of 0.5% by mass of the washing liquid, culture for 7 days at pH 7.5, and centrifuge to collect the wet-base bacteria; the silicate bacteria are added to the reactor at a ratio of 0.6-1.5% of the total mass of the absorption liquid.

[0009] Preferably, the culture process of Aspergillus aculeatus is to inoculate Aspergillus aculeatus into a solid culture medium to prepare an Aspergillus spore suspension, which is then inoculated into a liquid culture medium filled with a velvet filler, with an inoculation concentration of 0.1 to 1×10 6 / mL, and culture the biofilm for 3 days, then take out the filler; after taking out the filler, fix it to the fixed frame of the inner guide tube of the reactor, and the mass ratio of the filler to the absorption liquid is 25~40:100.

[0010] Preferably, the feldspar mineral is one or more of potassium feldspar, calcium feldspar or biotite, and the solid content of the feldspar mineral in the absorption slurry is 1.5-4.5%, where the percentage is mass percentage.

[0011] Preferably, the absorption liquid is prepared from urban domestic sewage and organic wastewater containing citric acid and acetic acid, and the chemical oxygen demand of the absorption liquid is controlled to be 350-500 mg / L.

[0012] Preferably, the CO2 concentration introduced into the reactor is 0.5-15% (volume percentage), the oxygen content is not less than 15% (volume percentage), and the residence time of the gas in the absorption system is 5-15s.

[0013] Preferably, the pH value of the absorption slurry in the reactor is controlled at 7.2~9.5. When the pH is lower than 7.2, a certain amount of absorption slurry is discharged from the bottom of the slurry making tank, and then an equal volume of fresh absorption slurry is added, and feldspar mineral is added at the same time, and its amount is 0.8~1.2 times the amount of solid matter in the waste absorption liquid.

[0014] Preferably, the quantitative absorption slurry accounts for 10-20% by mass of the total absorption slurry.

[0015] Preferably, the carbon fixation bioreactor includes a reactor body, a spiral nozzle, a guide inner tube, a fixed frame, a carbon dioxide aeration device, and an emptying pipe. The spiral nozzle is arranged at the top of the reactor body, and a guide inner tube is provided in the reactor body. The guide inner tube is a cylindrical structure, hollow inside and open at both ends. There is a distance between the guide inner tube and the inner wall of the reactor body. The fixed frame is arranged in the guide inner tube, the carbon dioxide aeration device is arranged at the bottom of the reactor body, an emptying pipe is provided at the bottom of the reactor body, and a velvet filler is installed in the fixed frame; the bottom of the reactor body is connected to the bottom of the pulping tank through a reflux pipe, the pulping tank is connected to the spiral nozzle through a delivery pipe, and the delivery pipe is provided with a delivery pump, the pulping tank is provided with a stirring device, and the bottom of the pulping tank is provided with a waste slurry discharge port.

[0016] Preferably, an observation and temporary feeding port is provided on the upper side of the reactor body, a tail gas discharge port is provided on the top of the reactor body, and the carbon dioxide aeration device is connected to the air intake buffer tank through a gas pipeline.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] 1. The method of the present invention uses feldspar minerals as raw materials to prepare pulp and fix CO2. The raw materials are widely available, the absorption rate is fast, and the carbon fixation process is obvious. The absorption liquid is prepared from urban domestic sewage and organic wastewater containing citric acid and acetic acid, and waste is treated with waste.

[0019] 2. The method of the present invention utilizes the metabolism of composite microorganisms to produce small molecule acids and other products, accelerates the decomposition of feldspar minerals and releases metal cations such as potassium and calcium into the absorption slurry. While improving the carbon fixation effect, the potassium in the feldspar minerals is converted into a soluble state and enters the absorption slurry. The carbon fixation absorption slurry is suitable for subsequent potassium extraction and utilization. The present invention has the dual effects of carbon fixation and potassium release. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of the carbon fixation bioreactor and pulping tank of the present invention;

[0021] In the figure: 1-reactor body, 2-spiral nozzle, 3-guiding inner tube, 4-fixed frame, 5-carbon dioxide aeration device, 6-emptying pipe, 7-velvet filler, 8-reflux pipe, 9-slurry making tank, 10-transfer pump, 11-stirring device, 12-waste slurry discharge port, 13-observation and temporary feeding port, 14-exhaust gas discharge port, 15-air intake buffer tank. DETAILED DESCRIPTION

[0022] The present invention is further described below with reference to the embodiments, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention fall within the scope of protection of the present invention.

[0023] Example 1

[0024] In this embodiment, the composite microbial method for enhancing carbon fixation of feldspar minerals is to inoculate Aspergillus aculeatus into a solid culture medium to prepare an Aspergillus spore suspension, which is then inoculated into a liquid culture medium filled with a velvety filler at an inoculation concentration of 0.5×10 6 / mL. After biofilm culture, the filler was removed and fixed to the fixed frame of the reactor's inner guide tube. The mass ratio of filler to absorption liquid in the reactor was 35:100. An absorption liquid with a chemical oxygen demand (COD) of 350 mg / L was prepared using municipal sewage and organic wastewater containing citric acid, of which the organic wastewater accounted for 5.0% by volume. Potassium feldspar crushed to less than 100 μm was added to the slurry tank at a ratio of 2.0% by mass of the absorption liquid. After stirring and mixing, the pH value of the absorption slurry was adjusted to 8.8. Thereafter, the absorption slurry was delivered to the reactor by a delivery pump. When the liquid level in the reactor reached a specified height, wet-based silicate bacteria after proliferation culture was added to the reactor at an amount of 1.0% of the total mass of the absorption liquid. Both the slurry tank and the reactor were operated at room temperature.

[0025] Carbon dioxide is mixed with air, with the concentrations of CO2 and O2 in the mixed gas being 15% and 16% respectively. After the delivery pump is started, the mixed gas fully contacts the absorption slurry in the guide inner tube, driving an upward flow. After the gas escapes from the liquid phase of the absorption system, it continues to diffuse upward and countercurrently contacts the circulating absorption slurry ejected from the spiral nozzle at the top of the reactor. The tail gas is discharged through the exhaust port. It has been calculated that the effective residence time of the gas in the reactor is 11 seconds.

[0026] When the pH value of the absorption system dropped to 7.2, the concentrations of Na, K, and Ca in the circulating liquid were 301, 130, and 14 mg / L, respectively, and the CO2 absorption efficiency of the reaction device dropped to 45%; in comparison, in the absorption device without adding microorganisms, the K concentration in the circulating liquid was only 12 mg / L, the CO2 absorption efficiency dropped to 41%, and when the pH value dropped by the same amount, the time was shortened by 35 minutes.

[0027] Example 2

[0028] In this example, the Aspergillus aculeatus spore suspension was inoculated into a liquid culture medium filled with a velvet filler at an inoculation concentration of 1.0×10 6 / mL, after biofilm culture, the filler was removed and fixed to the fixed frame of the inner guide tube of the reactor, and the mass ratio of the filler to the absorption liquid in the reactor was 25:100; an absorption liquid with a chemical oxygen demand (COD) of 420 mg / L was prepared using urban domestic sewage and organic wastewater containing acetic acid, wherein the volume ratio of the organic wastewater was 10.0%; potassium feldspar crushed to 75 μm was added to the slurry tank at a ratio of 4.5% of the mass of the absorption liquid, and the pH value of the slurry was adjusted to 9.5 after stirring and mixing; a mixed gas with a CO2 concentration of 6% was fed into the reactor through an aeration device, and the effective residence time of the gas in the reactor was about 6 seconds; the remaining operations were the same as in Example 1;

[0029] When the pH value of the absorption system dropped to 8.0, the concentrations of Na, K, and Ca in the circulating liquid were 52, 38, and 11 mg / L, respectively, and the CO2 absorption efficiency of the reaction device was 62%; in comparison, in the absorption device without adding microorganisms, the K concentration in the circulating liquid was only 16 mg / L, and the CO2 absorption efficiency was 55%.

[0030] Example 3

[0031] In this example, domestic sewage and citric acid organic wastewater were mixed to obtain a mixed solution with a COD value of 480 mg / L, wherein the volume ratio of the organic wastewater was 4.0%. After the absorption liquid was added to the slurry tank, potassium feldspar and calcium feldspar crushed to 75 μm were added at a ratio of 1.5% by weight, and the mass ratio of the two feldspar minerals was 1:1. The pH of the resulting absorption slurry was 9.5. The slurry was sent to a reactor, and wet-based silicate bacteria after proliferation culture were added at an amount of 0.5% of the total mass of the absorption liquid. The remaining operations were the same as in Example 1.

[0032] When the pH value of the absorption system dropped to 7.5, the K and Ca concentrations in the circulating fluid were 42 and 14 mg / L, respectively, and the CO2 absorption efficiency of the reactor was 53%. As the absorption operation continued, when the pH value dropped to 7.0, the K and Ca concentrations in the circulating fluid were 58 and 8 mg / L, respectively, and the CO2 absorption efficiency of the reactor dropped to 40.5%.

[0033] Example 4

[0034] In this example, the Aspergillus aculeatus spore suspension was inoculated into a liquid culture medium filled with a velvet filler at an inoculation concentration of 0.2×10 6 / mL, after biofilm culture, the filler is taken out and fixed to the fixed frame of the inner guide tube of the reactor, and the mass ratio of the filler to the absorption liquid in the reactor is 40:100; domestic sewage and citric acid organic wastewater are used to prepare an absorption liquid with a COD of 350 mg / L, and then a feldspar mineral mixture crushed to 100 μm is added at a ratio of 3.0% by mass, and the feldspar mineral mixture is obtained by mixing potassium feldspar, calcium feldspar and biotite at a mass ratio of 1:1:1; after the absorption slurry is prepared, its pH is not adjusted and it is then sent to the reactor; the rest of the operations are the same as in Example 1.

[0035] When the pH value of the absorption system is lower than 7.2, the K and Ca concentrations in the circulating liquid are 96 and 11 mg / L, respectively, and the CO2 absorption efficiency of the reaction unit drops to 42%; at this time, 1 / 8 of the absorption slurry is discharged from the bottom of the slurry tank, and then an equal volume of COD 350 mg / L absorption liquid is added, and feldspar mixed minerals are added at the same time, and the amount is equal to the mass of solid matter in the waste absorption slurry; after 10 minutes of operation, the pH value of the absorption slurry in the reactor rises again to 8.1, and the CO2 absorption efficiency is 48.7%.

[0036] Example 5

[0037] This embodiment is the same as Example 1 except that the mass ratio of filler to absorption liquid in the reactor is 32.5:100, the solid content of feldspar minerals in the absorption slurry is 4.5%, the chemical oxygen demand of the absorption liquid is controlled to 500 mg / L, and the CO2 concentration is 0.5%. On the basis of Example 1, the carbon fixation bioreactor includes a reactor body 1, a spiral nozzle 2, a flow guide inner cylinder 3, a fixed frame 4, a carbon dioxide aeration device 5, and an emptying pipe 6. The spiral nozzle 2 is arranged at the top of the reactor body 1, and the reactor body 1 A guide inner tube 3 is provided inside the guide inner tube 3, which is a cylindrical structure with a hollow interior and open at both ends. There is a distance between the guide inner tube 3 and the inner wall of the reactor body 1. The fixed frame 4 is provided in the guide inner tube 3. The carbon dioxide aeration device 5 is provided at the bottom of the reactor body 1. The bottom of the reactor body 1 is provided with an emptying pipe 6. The fixed frame 4 is filled with a velvet filler 7. The bottom of the reactor body 1 is connected to the bottom of the pulping tank 9 through a reflux pipe 8. The pulping tank 9 is connected to the spiral nozzle 2 through a delivery pipe, and the delivery pipe is provided with a A delivery pump 10 is provided, and a stirring device 11 is provided in the pulping tank 9. A waste slurry discharge port 12 is provided at the bottom of the pulping tank 9. When in use, the CO2 gas is mixed with air and then fed into the reactor body 1 through the carbon dioxide aeration device 5. The absorption slurry is in an upward liquid state in the guide inner tube 3, and is fully in contact with the biofilm formed by the microorganisms attached to and growing on the velvet filler 7 and the suspended microorganisms. After the absorption slurry rises, it flows downward along the space between the outer side of the guide inner tube and the side wall of the reactor body 1 and flows to the bottom of the reactor body 1. Then the absorption The slurry flows into the slurry making tank 9 (i.e., the circulation tank) through the reflux pipe 8; the absorption slurry is sent to the spiral nozzle 2 through the delivery pump 10 and sprayed out, and again contacts the CO2 escaping from the liquid absorption system in the reactor body 1 in countercurrent; when the system stops running, the absorption slurry is emptied through the drain pipe 6; when the pH value of the circulating liquid in the slurry making tank 9 is lower than 7.2, a certain amount of absorption slurry is discharged from the waste slurry discharge port 12 at the bottom of the slurry making tank 9, and an equal volume of absorption liquid is supplemented and feldspar mineral is added, the amount of which is 0.8 times the amount of solid matter in the waste absorption liquid, and then the cycle continues.

[0038] Example 6

[0039] This embodiment is the same as Example 5, except that the chemical oxygen demand of the absorption liquid is controlled to 425 mg / L and the CO2 concentration is 8.0%. Based on Example 5, an observation and temporary feeding port 13 is provided on the upper side of the reactor body 1, an exhaust gas discharge port 14 is provided on the top of the reactor body 1, and the carbon dioxide aeration device 5 is connected to the air inlet buffer tank 15 through a gas pipeline. The exhaust gas in the reactor body 1 is discharged through the exhaust gas discharge port 14. When the system of the present invention is started, the proliferated wet-based silicate bacteria can be added through the observation and temporary feeding port 13.

[0040] When the pH value of the absorption slurry in the reactor is lower than 7.2, a certain amount of absorption slurry is discharged from the bottom of the slurry making tank, and then an equal volume of fresh absorption slurry is added, and feldspar mineral is added at the same time, the amount of which is 1.2 times the amount of solid matter in the waste absorption liquid.

Claims

1. A method for enhancing carbon fixation of feldspar minerals by composite microorganisms, characterized in that The following steps are involved: S1. Aspergillus aculeatus is loaded onto a velvet filler, which is then fixed to the fixed frame of the inner guide tube of the carbon fixation bioreactor, and the silicate bacteria after proliferation and culture are added to the reactor; the feldspar mineral is crushed to a particle size of less than 100 μm and then mixed evenly with the absorption liquid in a pulping tank to form an absorption slurry, which is then pumped into the reactor containing Aspergillus aculeatus and silicate bacteria; the culturing process of the silicate bacteria is to use 0.5% citric acid to wash the root soil of the cotton bud stage, add potassium feldspar powder at 0.5% of the mass of the leaching liquid, culture at pH 7.5 for 7 days, and centrifuge to collect the wet base bacteria; the silicate bacteria are added to the reactor at a ratio of 0.6-1.5% of the total mass of the absorption liquid; the culturing process of the Aspergillus aculeatus is to inoculate the Aspergillus aculeatus into a solid culture medium to make an Aspergillus spore suspension, which is then inoculated into a liquid culture medium filled with velvet filler at an inoculation concentration of 0.1-1×10 6 / mL, biofilm culture for 3 days, after which the filler is removed; the filler is fixed to the fixed frame of the reactor's inner guide tube, with a mass ratio of filler to absorption liquid of 25-40:100; the absorption liquid is prepared from municipal sewage and organic wastewater containing citric acid and acetic acid, and the chemical oxygen demand of the absorption liquid is controlled to be 350-500 mg / L; S2 and CO2 are sent into the reactor through the aeration device at the bottom of the carbon fixation bioreactor, fully contacted with the absorption slurry in the guide inner tube and in an upward flow state, and at the same time fully contacted with the biofilm and suspended microorganisms; then the absorption slurry flows downward in the space outside the guide inner tube and inside the reactor to the bottom of the reactor and is discharged. The discharged absorption slurry is transported by a delivery pump, sprayed out from the spiral nozzle at the top of the reactor, and countercurrently contacts with the CO2 escaping from the liquid absorption system in the reactor; CO2 is finally converted into carbonate precipitates and discharged.

2. The method for enhancing carbon fixation of feldspar minerals by composite microorganisms according to claim 1, characterized in that The feldspar mineral is one or more of potassium feldspar, calcium feldspar or biotite, and the solid content of the feldspar mineral in the absorption slurry is 1.5-4.5%, where the percentage is mass percentage.

3. The method for enhancing carbon fixation of feldspar minerals by composite microorganisms according to claim 1, characterized in that The CO2 concentration introduced into the reactor is 0.5~15%, the oxygen content is not less than 15%, and the residence time of the gas in the absorption system is 5~15s.

4. The method for enhancing carbon fixation of feldspar minerals by composite microorganisms according to claim 1, characterized in that The pH value of the absorption slurry in the reactor is controlled at 7.2~9.

5. When the pH is lower than 7.2, a certain amount of absorption slurry is discharged from the bottom of the slurry making tank, and then an equal volume of fresh absorption slurry is added. At the same time, feldspar mineral is added, and its amount is 0.8~1.2 times the amount of solid matter in the waste absorption liquid.

5. The method for enhancing carbon fixation of feldspar minerals by composite microorganisms according to claim 4, characterized in that The quantitative absorption slurry accounts for 10-20% of the total absorption slurry by mass.

6. The method for enhancing carbon fixation of feldspar minerals by composite microorganisms according to claim 1, characterized in that The carbon fixation bioreactor comprises a reactor body (1), a spiral nozzle (2), a flow guide inner tube (3), a fixed frame (4), a carbon dioxide aeration device (5), and an exhaust pipe (6). The spiral nozzle (2) is arranged at the top of the reactor body (1). The reactor body (1) is provided with a flow guide inner tube (3). The flow guide inner tube (3) is a cylindrical structure with a hollow interior and open at both ends. There is a distance between the flow guide inner tube (3) and the inner wall of the reactor body (1). The fixed frame (4) is provided on the flow guide inner tube (3). The carbon dioxide aeration device (5) is arranged at the bottom of the reactor body (1), the bottom of the reactor body (1) is provided with an emptying pipe (6), and the fixed frame (4) is provided with a velvet filler (7); the bottom of the reactor body (1) is connected to the bottom of the pulping tank (9) through a reflux pipe (8), the pulping tank (9) is connected to the spiral nozzle (2) through a delivery pipe, and the delivery pipe is provided with a delivery pump (10), the pulping tank (9) is provided with a stirring device (11), and the bottom of the pulping tank (9) is provided with a waste slurry discharge port (12).

7. The method for enhancing carbon fixation of feldspar minerals by composite microorganisms according to claim 6, characterized in that An observation and temporary feeding port (13) is provided on the upper side of the reactor body (1), an exhaust gas discharge port (14) is provided on the top of the reactor body (1), and the carbon dioxide aeration device (5) is connected to the air inlet buffer tank (15) through a gas pipeline.

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