Method for enhancing methane production efficiency of anaerobic digestion grease based on addition of nano magnetite
By adding nanomagnetite to the anaerobic digestion system, the direct transmission of electrons between species and microbial aggregation are optimized, the problem of low degradation efficiency of long-chain fatty acids in waste oil and fat is solved, the methane production is significantly improved, and the efficient conversion of oil and fat to methane is achieved.
Patent Information
- Application Number
- CN202510072001.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-17
- Publication Date
- 2025-04-04
AI Technical Summary
The degradation efficiency of long-chain fatty acids during the anaerobic digestion process is low, resulting in limited methane conversion efficiency, and the high fat content of the oil and fat forms an oil film to hinder microbial contact and degradation reaction.
By adding different concentrations of nanomagnetite (Fe3O4) to the anaerobic digestion system, direct electron transfer and microbial aggregation between species are optimized, and the oil degradation rate and methane production are improved.
By adjusting the addition amount of nanomagnetite, the degradation rate and methane production of greases were significantly improved. When the maximum addition amount was 5 g/L, methane production increased by 65.2%, and methane production was maximized while reducing sludge production.
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Figure CN119753033A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of anaerobic digestion of organic waste, and specifically relates to a method for enhancing the methane production efficiency of anaerobic digestion of oil and fat based on adding nano magnetite Background Art
[0002] Waste oil and fat has a high potential for methane production, but the biggest challenge in its anaerobic digestion process is the degradation of long-chain fatty acids (products of oil hydrolysis), which can only be achieved under the synergistic action of acidifying bacteria and methanogenic archaea. This is also a key factor limiting the conversion efficiency during the anaerobic digestion of oil and fat to produce methane. In addition, the high fat content of oil and fat often leads to the formation of oil film, which hinders the contact of microorganisms and the progress of degradation reactions, reducing the reaction efficiency. The accumulation of oil degradation products, especially the accumulation of fatty acids, may cause system acidification, thereby inhibiting the activity of microorganisms and affecting the stability of the reaction. Therefore, how to effectively accelerate the degradation of oil and fat, especially the degradation of long-chain fatty acids, has become an urgent problem to be solved in the process of optimizing the anaerobic digestion of oil and fat.
[0003] Nano-magnetite (Fe3O4), as an iron-based conductive material, can not only promote the direct interspecies electron transfer between acidifying bacteria and methanogens, but also reduce the energy consumed by microorganisms to synthesize conductive pili to promote direct interspecies electron transfer. Its addition improves the efficiency of electron transfer during anaerobic digestion of oils and fats. In addition, nano-magnetite can also promote the aggregation of microorganisms and reduce the barrier effect of oil membranes on microorganisms, thereby further improving the treatment efficiency of oils and fats and their degradation products (such as fatty acids), ultimately increasing methane production and stabilizing system operation. Summary of the invention
[0004] The purpose of the present invention is to maximize the effect of nano-magnetite in the anaerobic digestion system, enhance the efficiency of oil to methane conversion, optimize its promotion effect on direct interspecies electron transfer by adjusting the dosage of nano-magnetite, thereby increasing the oil degradation rate and methane production, and provide a method for enhancing the methane production efficiency of anaerobic digestion of oil based on the addition of nano-magnetite.
[0005] To achieve the above object, the present invention is implemented according to the following technical solutions:
[0006] A method for enhancing the methane production efficiency of anaerobic digestion of oil based on the addition of nano-magnetite, by changing the dosage of nano-magnetite, optimizes its synergistic effect in the anaerobic digestion process. The specific dosages of nano-magnetite are: 1 g / L, 3 g / L, 5 g / L, 10 g / L and 15 g / L. The initial dosage of each group is gradually increased to explore the effects of different dosages on oil degradation rate and methane production. BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Figure 1 To enhance the efficiency of methanogenesis in anaerobic digestion of oil by adding nano magnetite
[0008] Figure 2 Volatile solid (VS) content of the control group and the nano group on the 47th day DETAILED DESCRIPTION
[0009] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.
[0010] The method for enhancing the methane production efficiency of anaerobic digestion of oil and fat based on adding nano-magnetite according to an embodiment of the present invention is described in detail below.
[0011] Example
[0012] This embodiment provides a method for enhancing the methane production efficiency of anaerobic digestion of oil based on adding nano magnetite, which specifically includes the following steps:
[0013] In this example, three serum bottles with a working volume of 150 mL were set as parallel samples. In the initial stage of the reaction, 15 mL of inoculum was added to the serum bottles according to the ratio of substrate to inoculum (gVS / gVS) of 1:2, and then the corresponding amount of substrate was added to the reactor, and nitrogen was passed through the serum bottles for 5 minutes, and the air was exhausted to maintain anaerobic conditions.
[0014] All serum bottles were subjected to anaerobic digestion at a temperature of 37°C and a rotation speed of 150 rpm. The methane concentration was tested regularly and the methane content was calculated. After 47 days of anaerobic digestion, the cumulative methane production and the VS content after the reaction were as follows: Figure 1 , as shown in 2 (control group).
[0015] Comparative Example 1
[0016] This embodiment provides a method for enhancing the methane production efficiency of anaerobic digestion of oil based on adding nano magnetite, which specifically includes the following steps:
[0017] In this example, three serum bottles with a working volume of 150 mL were set as parallel samples. In the initial stage of the reaction, 1 g / L nanomagnetite was added, and then 15 mL of inoculum was added to the serum bottles according to the ratio of substrate to inoculum (gVS / gVS) of 1:2, and then the corresponding amount of substrate was added to the reactor, and nitrogen was passed through the serum bottles for 5 minutes, and the air was exhausted to maintain anaerobic conditions.
[0018] All serum bottles were subjected to anaerobic digestion at a temperature of 37°C and a rotation speed of 150 rpm. The methane concentration was tested regularly and the methane content was calculated. After 47 days of anaerobic digestion, the cumulative methane production and the VS content after the reaction were calculated as follows: Figure 1 , as shown in 2 (Nano group 1).
[0019] Comparative Example 2
[0020] This embodiment provides a method for enhancing the methane production efficiency of anaerobic digestion of oil based on adding nano magnetite, which specifically includes the following steps:
[0021] In this example, three serum bottles with a working volume of 150 mL were set as parallel samples. At the initial stage of the reaction, 3 g / L nanomagnetite was added, and then 15 mL of inoculum was added to the serum bottles according to the ratio of substrate to inoculum (gVS / gVS) of 1:2, and then the corresponding amount of substrate was added to the reactor, and nitrogen was passed through the serum bottles for 5 minutes, and the air was exhausted to maintain anaerobic conditions.
[0022] All serum bottles were subjected to anaerobic digestion at a temperature of 37°C and a rotation speed of 150 rpm. The methane concentration was tested regularly and the methane content was calculated. After 47 days of anaerobic digestion, the cumulative methane production and the VS content after the reaction were calculated as follows: Figure 1 , as shown in 2 (Nano group 2).
[0023] Comparative Example 3
[0024] This embodiment provides a method for enhancing the methane production efficiency of anaerobic digestion of oil based on adding nano magnetite, which specifically includes the following steps:
[0025] In this example, three serum bottles with a working volume of 150 mL were set as parallel samples. At the initial stage of the reaction, 5 g / L nanomagnetite was added, and then 15 mL of inoculum was added to the serum bottles according to the ratio of substrate to inoculum (gVS / gVS) of 1:2, and then the corresponding amount of substrate was added to the reactor, and nitrogen was passed through the serum bottles for 5 min, and the air was exhausted to maintain anaerobic conditions.
[0026] All serum bottles were subjected to anaerobic digestion at a temperature of 37°C and a rotation speed of 150 rpm. The methane concentration was tested regularly and the methane content was calculated. After 47 days of anaerobic digestion, the cumulative methane production and the VS content after the reaction were calculated as follows: Figure 1 , as shown in 2 (Nano group 3).
[0027] Comparative Example 4
[0028] This embodiment provides a method for enhancing the methane production efficiency of anaerobic digestion of oil based on adding nano magnetite, which specifically includes the following steps:
[0029] In this example, three serum bottles with a working volume of 150 mL were set as parallel samples. In the initial stage of the reaction, 10 g / L nanomagnetite was added, and then 15 mL of inoculum was added to the serum bottles according to the ratio of substrate to inoculum (gVS / gVS) of 1:2, and then the corresponding amount of substrate was added to the reactor, and nitrogen was passed through the serum bottles for 5 min, and the air was exhausted to maintain anaerobic conditions.
[0030] All serum bottles were subjected to anaerobic digestion at a temperature of 37°C and a rotation speed of 150 rpm. The methane concentration was tested regularly and the methane content was calculated. After 47 days of anaerobic digestion, the cumulative methane production and the VS content after the reaction were calculated as follows: Figure 1 , as shown in 2 (Nano group 4).
[0031] Comparative Example 5
[0032] This embodiment provides a method for enhancing the methane production efficiency of anaerobic digestion of oil based on adding nano magnetite, which specifically includes the following steps:
[0033] In this example, three serum bottles with a working volume of 150 mL were set as parallel samples. In the initial stage of the reaction, 15 g / L nanomagnetite was added, and then 15 mL of inoculum was added to the serum bottles according to the ratio of substrate to inoculum (gVS / gVS) of 1:2, and then the corresponding amount of substrate was added to the reactor, and nitrogen was passed through the serum bottles for 3 min, and the air was exhausted to maintain anaerobic conditions.
[0034] All serum bottles were subjected to anaerobic digestion at a temperature of 37°C and a rotation speed of 150 rpm. The methane concentration was tested regularly and the methane content was calculated. After 47 days of anaerobic digestion, the cumulative methane production and the VS content after the reaction were calculated as follows: Figure 1 , as shown in 2 (Nano group 5).
[0035] At the end of anaerobic digestion, the cumulative methane production of the example was 428.6 mL / gVS added , VS content is 6.4 g / L; the cumulative methane production of Comparative Example 1 is 434.0 mL / gVS added , VS content is 5.4 g / L; the cumulative methane production of Comparative Example 2 is 565.7 mL / gVS added , VS content is 4.8 g / L; the cumulative methane production of Comparative Example 3 is 707.9 mL / gVS added, VS content is 4.2 g / L; the cumulative methane production of comparative example 4 is 401.8 mL / gVS added , VS content is 3.4 g / L; the cumulative methane production of comparative example 5 is 344.8 mL / gVS added , VS content is 3.5 g / L.
[0036] When the nano-magnetite concentration increased from 1 g / L to 5 g / L (Comparative Example 3), the methane production reached a maximum of 707.9 mL / gVS added , compared with the control group (Example) without the addition of nano-magnetite, the methane production increased by 65.2%. At the same time, the volatile solid (VS) content dropped to 4.2 g / L, indicating that the highest conversion efficiency of oil to methane was achieved while the sludge biomass decreased. As the nano-magnetite dosage was further increased to 10 g / L and 15 g / L, although the VS value continued to decrease, the methane production decreased, indicating that the excessive nano-magnetite inhibited the activity of microorganisms.
[0037] In summary, the addition of nano-magnetite significantly affects the efficiency of methane production in anaerobic digestion of oil and fat, with 5 g / L being the optimal dosage. The cumulative methane production increased by 65.2% compared with the control group, maximizing the methane production while reducing the sludge production. The present invention provides a new technical path for the efficient treatment and resource utilization of waste oil and fat.
Claims
1. A method for enhancing the methane production efficiency of anaerobic digestion of oil based on adding nano magnetite, characterized in that: Nano-magnetite accelerates direct interspecies electron transfer, optimizes the electron transfer efficiency during anaerobic digestion, promotes oil degradation, improves the removal rate of volatile solids, and maximizes methane production by adjusting the dosage of nano-magnetite.
2. The method of enhancing the methane production efficiency of anaerobic digestion of oil and fat by adding nano magnetite according to claim 1, characterized in that: A serum bottle with a working volume of 150 mL was used as a reactor. Inoculum, substrate and five different dosages of nano-magnetite were added into the reactor to determine the effect of the addition of nano-magnetite on methane production in anaerobic digestion of oil.
3. The method of enhancing the methane production efficiency of anaerobic digestion of oil and fat by adding nano magnetite according to claim 2, characterized in that: The particle size of nano magnetite is 1-30 nm, and the dosage is 1-15 g / L.
4. The method of enhancing the methane production efficiency of anaerobic digestion of oil and fat by adding nano magnetite according to claim 2, characterized in that: Sludge obtained from a reactor for anaerobic digestion of citric acid wastewater was used as inoculum and oil as substrate.
5. The method of enhancing the methane production efficiency of anaerobic digestion of oil and fat by adding nano magnetite according to claim 2, characterized in that: In order to maintain anaerobic conditions, nitrogen was passed through the sealed reactors of all groups for 5 minutes.
6. The method of enhancing the methane production efficiency of anaerobic digestion of oil and fat by adding nano magnetite according to claim 2, characterized in that: All reactors were stirred in a temperature-controlled shaker at 37°C with a stirring speed of 150 rpm.
7. The method of enhancing the methane production efficiency of anaerobic digestion of oil and fat by adding nano magnetite according to claim 4, characterized in that: The ratio of substrate to inoculum (gVS / gVS) was 0.5.