A method for synergistically sequestering carbon dioxide by using microorganisms and waste residues

Abstract

The application discloses a method for synergistically fixing carbon by using microorganisms and waste residues, which comprises the following steps: (1) adding clean water and nutrients required for the growth of microorganisms into a microbial culture tank, and stirring and mixing to obtain a microbial liquid culture medium; (2) inoculating microorganisms with a mineralization and deposition function into the microbial liquid culture medium, and performing constant-temperature fermentation culture, and filtering to obtain a microbial mineralizer; and (3) mixing the microbial mineralizer with waste residues, and placing the mixture in an environment containing CO2 to fix carbon. The method has the characteristics of more remarkable carbon fixation effect, wider applicability, more friendly environment, higher resource recycling rate and the like, and can be used as an important technical means for carbon sequestration and carbon neutralization of industrial exhaust gas.

Description

Technical Field

[0001] This invention relates to a method for carbon fixation of industrial waste residue, and more particularly to a method for synergistic carbon fixation of waste residue using microorganisms. Background Technology

[0002] Carbon capture and storage (CCS) technology has become one of the most important means of mitigating the global greenhouse effect. Existing research has shown that using alkaline industrial waste to store CO2 can significantly reduce total annual CO2 emissions. Industrial waste treated with carbonation can absorb and fix carbon dioxide emitted from industrial production, mitigating climate change and air pollution, and possesses enormous economic and environmental value.

[0003] However, the carbon sequestration rate of alkaline industrial waste residues under normal temperature and pressure conditions is currently not high. To improve the carbon sequestration rate, high-energy-consuming and stringent conditions such as pressurization and heating are generally required. With the continuous application and development of biotechnology in industrial production, the use of microbial technology has become an important means to improve carbon sequestration. Microbial carbon sequestration utilizes the mineralization and accelerated conversion of metabolic substances such as enzymes secreted by microorganisms to generate more stable carbonates, thereby improving the carbon sequestration effect of industrial waste residues.

[0004] Patent ZL201510907609.1 discloses a method for preparing solid waste building materials based on microbial mineralization induction technology; patent CN201710275551.2 discloses a method for preparing microbially mineralized stainless steel slag bricks; patent CN201710275422.3 discloses a method for preparing red mud building materials based on microbial accelerated mineralization; and patent application CN201810384096.4 discloses a method for manufacturing microbial thermal insulation building materials. These methods primarily aim to utilize microbial technology to prepare qualified building materials with good performance. However, the carbon sequestration capacity of the waste residue is not high, and many carbonizable minerals remain unutilized. The treated waste residue products still possess significant carbonization potential. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a method for synergistic carbon fixation of waste residue by utilizing microorganisms and waste residue, which can significantly improve the carbon fixation rate of waste residue.

[0006] Technical solution: The method of carbon sequestration using microorganisms and waste residue of the present invention includes the following steps:

[0007] (1) Add water and nutrients required for microbial growth to a microbial culture tank, mix well, and obtain a microbial liquid culture medium;

[0008] (2) Microbial strains with mineralization deposition function are inoculated into microbial liquid culture medium, fermented at constant temperature, and the supernatant is filtered to obtain microbial mineralizing agent.

[0009] (3) Mix the microbial mineralizing agent with the waste residue and place it in an environment containing CO2 to fix carbon, thereby obtaining carbon-fixed waste residue.

[0010] In step (2), the constant temperature fermentation process is as follows: turn on the constant temperature stirring system, and culture at 20-40℃ and 100-300r / min for 12-72h. After the OD value of the bacterial solution rises to above 2, filter it and take the clear liquid as a microbial mineralizing agent.

[0011] Among them, the microorganisms with mineralization function are mostly heterotrophic facultative bacteria, and the microorganisms with mineralization deposition function are urease-producing or non-urease-producing bacteria, including Bacillus pasteurellii, Bacillus spheroides, Bacillus alkalophilus, Bacillus mucilaginosus, Bacillus cereus, Bacillus subtilis, Bacillus pasteurellii, and Bacillus rock-resistant bacteria, etc. The added microbial strains may contain one or more of these bacteria; the microbial strains with mineralization deposition function are at least one of Bacillus mucilaginosus, Bacillus pasteurellii, Bacillus pumilus, or Bacillus alkalophilus. The added microbial strains may contain one or more bacterial powders; nutrients include carbonaceous substances, nitrogenous substances, and inorganic salts, etc. Carbonaceous substances may include sucrose, glucose, maltose, starch, and molasses, etc.; nitrogenous substances may include yeast extract, beef extract, urea, fish meal, soybean meal, peptone, and ammonium sulfate, etc.; inorganic salts may include sodium chloride, magnesium sulfate, and dipotassium hydrogen phosphate, etc.

[0012] In step (3), the microbial mineralizing agent accounts for 1% to 10% of the mass of the waste residue.

[0013] The specific process of step (3) is as follows: the microbial mineralizing agent is taken at a weight percentage of 1% to 10% of the waste residue. During spraying, it needs to be stirred continuously to ensure thorough and uniform mixing. The material is then naturally cured or placed in a carbonization curing box, and then sealed and purged with CO2 gas at a pressure of 0.1±0.01MPa with a carbon dioxide volume fraction of 20% to 95%. After carbonization at 95±5%RH and 20±2℃ for 2 to 48 hours, the solidified carbon waste residue is obtained.

[0014] The introduced gas can be waste gas from metal smelting plants, cement industry and coal power industry after treatment, industrial and commercial grade carbon dioxide gas, with a concentration of 10% to 95% and a pressure of 0.1 ± 0.01 MPa.

[0015] In step (3), the waste residue is industrial waste residue powder that has been dried, crushed, and ground. The waste residue mainly includes the following categories: slag, carbide slag, steel slag, blast furnace slag, tailings slag, red mud, and other metallurgical industry waste residue; recycled concrete powder and other construction industry waste residue; dolomite tailings and other calcium-magnesium phase alkaline mineral tailings; and mining waste sedimentary rocks, coal gangue, and other mining and mineral processing industry waste residue. These are processed by crushing, grinding, screening, and shaping to a specific surface area greater than 300 m².2 / kg of powder.

[0016] Principle: Metabolic substances produced during the life activities of microorganisms can accelerate the combination of CO2 and water, improve the conversion efficiency of mineral phases, and at the same time, microorganisms adsorb on the surface of mineral phases as nucleation sites to form more stable carbonates, further increasing the amount of carbon dioxide absorbed by industrial waste and improving the carbon fixation rate of industrial waste.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant effects: (1) The present invention can promote the carbonization of more calcium and magnesium mineral phases in the waste residue, accelerate the absorption of more carbon dioxide, and stably seal CO2 in the waste residue, thereby improving carbon fixation efficiency and carbon fixation amount; the carbon fixation effect of this technology is good, the cost is low, and the consumption is high, which has outstanding social benefits; (2) Compared with traditional methods such as increasing pressure and changing temperature, the microbial technology is more suitable for milder conditions, takes from nature, and can efficiently utilize the alkaline mineral phases in industrial waste residue that are difficult to dissolve and have low carbonization activity under normal temperature and pressure, and combine them with carbon dioxide to form stable carbonates, which has the characteristics of high efficiency and energy saving, simple operation, safety and environmental protection and economic applicability; (3) Using environmentally friendly microbial carbon fixation technology to combine industrial waste residue and industrial waste gas in industrial waste is of great significance for carbon peaking and carbon neutrality. Attached Figure Description

[0018] Figure 1 The graph shows the carbon fixation content test curves for Example 1 and steel slag powder without microorganisms.

[0019] Figure 2 This is a comparison chart showing the carbon sequestration effects of three types of waste residue particles—steel slag powder, recycled concrete powder, and dolomite tailings—in Example 2. Detailed Implementation

[0020] The present invention will now be described in further detail.

[0021] Example 1

[0022] In this embodiment, the microbial species with mineralization deposition function is Bacillus that produces carbonic anhydrase.

[0023] This embodiment utilizes a method for synergistic carbon sequestration between microorganisms and waste residue, with the following specific steps:

[0024] (1) Preparation of microbial mineralizing agent: Bacillus was inoculated into a sterile liquid culture medium solution containing 4g peptone, 4g beef extract, 5g NaCl, and 0.5g MgSO4 per liter of culture medium. The solution was placed in a shaker and incubated at 20℃ and 170r / min for 24 hours. The scum was filtered and the clear liquid was obtained to obtain the microbial mineralizing agent for later use.

[0025] (2) Steel slag particles were ground to below 200 mesh, and the specific surface area was measured to be 380 m². 2 / kg, for future use;

[0026] (3) Take a microbial mineralizing agent at a mass percentage of 2% of the steel slag powder and mix it with a certain mass of water. Spray the mixture evenly onto the steel slag powder, where the total volume of the liquid added accounts for 20% of the mass percentage of the waste slag powder. After stirring and mixing, place the mixture in a carbonization box with a carbon dioxide concentration of 20%, a humidity of 95±5%RH, and a temperature of 20±2℃. After carbonization for 24 hours, the solidified steel slag is obtained and its carbon fixation rate is measured.

[0027] In addition, carbon-fixing steel slag prepared without the addition of microorganisms was used as a control group to test its carbon fixation rate.

[0028] like Figure 1 As shown, microbial treatment can increase the carbon fixation content of steel slag, from 9.37% to 14.55%, which is 55.28% higher than that of pure carbonized steel slag. This indicates that microbial technology can effectively utilize the mineral phases with low carbonization activity in steel slag, promote their absorption of carbon dioxide and their transformation into carbonate minerals, and further stimulate the carbon fixation potential of industrial waste slag.

[0029] Example 2

[0030] The difference between Example 1 and Example 2 is that:

[0031] In step (2), take three types of industrial waste residue particles: steel slag powder, recycled concrete powder, and dolomite tailings, crush and grind them to below 200 mesh, and then screen them for later use.

[0032] (3) Take a microbial mineralizing agent at a mass percentage of 2% of the waste residue powder, mix it with water and spray it evenly onto the surface of the steel slag powder. The total volume of the liquid added should be 20% of the mass percentage of the waste residue powder. After mixing, place it in a carbonization reactor with a carbon dioxide concentration of 95% and cure it for 24 hours as standard. Then, use it as carbon-fixed waste residue and measure its carbon fixation amount.

[0033] like Figure 2 As shown, microorganisms can increase the carbon sequestration of waste residues under normal temperature and pressure. The carbon sequestration of steel slag increased from 110.5 g / kg to 162.2 g / kg, the carbon sequestration of recycled concrete powder increased from 57.4 g / kg to 87.2 g / kg, and the carbon sequestration of dolomite tailings increased from 12.3 g / kg to 19.1 g / kg. Microbial technology can be applied to various types of waste residues, significantly improving their carbon sequestration, and has a wide range of applications.

[0034] Example 3

[0035] The difference between Example 1 and Example 2 is that:

[0036] In step (3), microbial mineralizing agent is taken at a mass percentage of 0%, 5%, and 15% of the steel slag powder. After being mixed with water, it is sprayed evenly onto the surface of the steel slag powder. The total volume of the added liquid accounts for 20% of the mass percentage of the waste slag powder. In addition, carbon-fixed steel slag is prepared without adding microbial agent as a control group, and its carbon fixation rate is tested.

[0037] The experimental results showed that as the amount of microbial mineralizer increased, the carbon fixation of steel slag first increased and then leveled off, with the carbon fixation amounts being 9.32%, 15.67%, and 14.15%, respectively. This indicates that the use of microorganisms can significantly improve the carbon fixation of waste slag.

Claims

1. A method for synergistic carbon sequestration using microorganisms and waste residue, characterized in that, Includes the following steps: (1) Add water and nutrients required for microbial growth to a microbial culture tank, stir and mix to obtain a microbial liquid culture medium; (2) Microbial strains with mineralization deposition function are inoculated into microbial liquid culture medium, fermented at constant temperature, and the supernatant is filtered to obtain microbial mineralizing agent; the process of constant temperature fermentation is as follows: turn on the constant temperature stirring system, and culture at 20~40℃ and 100~300r / min for 12~72h. When the OD value of the bacterial solution rises to above 2, filter and take the supernatant as microbial mineralizing agent; the microbial strains with mineralization deposition function are at least one of Bacillus pasteurellii, Bacillus pumilus, Bacillus mucilaginosus, other microorganisms that can produce carbonic anhydrase or alkalophilic Bacillus. (3) The microbial mineralizing agent is mixed with the waste residue and placed in an environment containing CO2 for carbon fixation to obtain carbon-fixed waste residue; the microbial mineralizing agent accounts for 1%~10% of the mass of the waste residue; the waste residue has a specific surface area greater than 300 m². 2 / kg of powder.

2. The method for synergistic carbon sequestration using microorganisms and waste residue according to claim 1, characterized in that, In step (3), the volume fraction of CO2 is 20% to 95%.

3. The method for synergistic carbon sequestration using microorganisms and waste residue according to claim 1, characterized in that, In step (3), the environmental conditions for carbon fixation are: relative humidity of (90±5)% and pressure of 0.1±0.01MPa.

4. The method for synergistic carbon sequestration using microorganisms and waste residue according to claim 1, characterized in that, In step (3), the source of the waste residue is at least one of coal gangue, carbide slag, ore slag, nickel slag, lithium slag, steel slag, red mud, dolomite tailings, copper slag, iron tailings, calcium magnesium silicate minerals, recycled sand powder, recycled concrete or silicate cement.

5. The method for synergistic carbon sequestration using microorganisms and waste residue according to claim 1, characterized in that, In step (3), the waste residue is alkaline industrial waste residue powder that has been crushed, dried and ground.

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