Method for regulating fatty acid metabolism by using condiments to strengthen anaerobic digestion of kitchen waste to produce biogas

Abstract

The invention discloses a method for regulating fatty acid metabolism by utilizing condiments to strengthen anaerobic digestion of kitchen waste to produce marsh gas, and relates to the field of kitchen waste treatment.The method comprises the following steps that piperine condiments in the kitchen waste are recognized and utilized, residual sludge is added into the kitchen waste containing piperine, the mixture is mixed to be uniform, and the marsh gas is obtained; controlling the concentration of piperine in the mixed material within a certain range interval, and adjusting the pH value; and feeding the treated mixed material into an anaerobic digestion reactor, and monitoring the biogas yield and the daily gas yield, so as to realize the enhancement of biogas production by anaerobic digestion of the kitchen waste. The risk of acidification caused by propionic acid accumulation in the kitchen waste anaerobic digestion reactor can be effectively eliminated, and stable operation of the system is ensured; fatty acid such as propionic acid is used as an important substrate for methane production and can be thoroughly utilized to further strengthen methane production, and the resource recycling rate of organic solid waste is effectively increased; the applicability of the kitchen waste anaerobic digestion reactor is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of anaerobic digestion and gas production of kitchen waste, and in particular to a method for enhancing biogas production by anaerobic digestion of kitchen waste by regulating fatty acid metabolism through seasonings. Background Art

[0002] Traditional disposal methods, such as landfill and incineration, face bottlenecks such as dioxin pollution, land occupation, and greenhouse gas emissions. Anaerobic digestion, which converts organic matter into biogas through microbial activity, is one of the most cost-effective methods for biomass energy recovery and is recognized as a preferred option for the resource recovery and treatment of organic solid waste.

[0003] Food waste is rich in biodegradable carbohydrates, lipids, and proteins, and possesses high organic carbon content. During anaerobic digestion, these substances are rapidly hydrolyzed and acidified to produce large quantities of short-chain fatty acids, leading to a significant accumulation of fatty acids and acidification. This continued accumulation of fatty acids can cause a decrease in the pH within the anaerobic system, inhibiting the activity of methanogens and causing system instability or even collapse. Thermodynamically, the Gibbs free energy for the decomposition of propionic acid to acetic acid is positive, meaning that this reaction is unlikely to proceed spontaneously under standard conditions. Consequently, short-chain fatty acids, particularly propionic acid, have long been considered key inhibitors in anaerobic digestion systems, and their concentration and response are crucial indicators for assessing system stability. Therefore, effectively preventing acidification and improving system stability when using food waste for anaerobic digestion of biogas are key challenges in efficiently producing biogas through anaerobic digestion of food waste. Summary of the Invention

[0004] To address the problem of excessive accumulation of organic acids inhibiting methanogens in anaerobic digestion systems of food waste, while simultaneously improving the resource utilization efficiency of organic solid waste and biogas recovery, the present invention provides a method for enhancing methanogenesis in anaerobic digestion of food waste by regulating fatty acid metabolism using a condiment (piperine).

[0005] A method for enhancing biogas production by anaerobic digestion of food waste by regulating fatty acid metabolism using condiments is specifically accomplished by the following steps:

[0006] S1. Identify and utilize piperine condiment in food waste, add excess sludge to food waste containing piperine, mix evenly, control the concentration of piperine in the mixture within a certain range, and adjust the pH value;

[0007] S2. The mixed material treated in step S1 is fed into an anaerobic digestion reactor, and the biogas production and daily gas production are monitored to enhance the biogas production by anaerobic digestion of the food waste.

[0008] Furthermore, in step S1, the food waste is sorted and crushed to a particle size of 1 to 5 mm, preferably 1 to 3 mm, with a total solid content (TS) of 58 to 100 g / L, of which volatile organic compounds (VS) account for more than 98% of the total solids.

[0009] Furthermore, in step S1, the mass ratio of organic matter in the food waste and the residual sludge in the mixed material is 1:1 to 1:2, and the pH value is 6 to 7.

[0010] Furthermore, in step S1, the concentration of piperine in the mixed material is 0-3 mg / g VS.

[0011] Furthermore, in step S2, the anaerobic digestion reactor needs to be inoculated with anaerobic sludge when it is started, and the inoculation ratio is 9:1 to 4:1, preferably 9:1 to 7:1.

[0012] Furthermore, in step S2, the temperature of the anaerobic digestion reactor is 30-37° C., preferably 35° C., the rotation speed is 150 rpm, and the pH is 6-8, preferably 7.

[0013] Glossary:

[0014] Residual sludge: refers to the sludge produced during the activated sludge treatment process.

[0015] Anaerobic sludge: refers to sludge that has undergone anaerobic digestion treatment.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) The present invention utilizes the condiment piperine remaining in food waste. This condiment is then digested anaerobically along with the food waste, achieving effective biogas production from the food waste and stabilizing the anaerobic fermentation system. This method not only reduces reliance on external chemical additives but also opens up a new avenue for the recycling of condiments.

[0018] (2) The present invention proposes an innovative method for treating food waste, which can effectively eliminate the risk of acidification caused by the accumulation of propionic acid in the anaerobic digestion reactor of food waste, ensuring the stable operation of the system; and fatty acids such as propionic acid are important substrates for methane production, and their thorough utilization can further enhance biogas production and effectively improve the resource recycling rate of organic solid waste; further improving the applicability of the anaerobic digestion reactor of food waste.

[0019] (3) Through in-depth research and precise chemical ratios, the present invention recycles condiments from food waste, not only improving the anaerobic fermentation efficiency of food waste but also significantly reducing secondary pollution that may be caused during the treatment process. Simultaneously, it reduces dependence on external chemical additives, further reducing treatment costs. Furthermore, the introduction of piperine optimizes the electron transfer efficiency of the fermentation system, promotes electron transfer activity between microbial cells, and opens up more internal channels for the biogas production process.

[0020] (4) This invention fully demonstrates the potential for efficient utilization of existing waste resources. Its innovation lies in the clever use of condiments naturally retained in food waste to achieve a true "waste-to-pollution" approach, opening up an unprecedented new path in the fields of environmental protection and resource conservation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a graph of the cumulative methane production of the embodiment of the present invention and the control group.

[0022] Figure 2 2 is a comparison chart of the changes in acetic acid (a), propionic acid (b), and valeric acid (c) during anaerobic co-digestion in the embodiment of the present invention and the control group. DETAILED DESCRIPTION

[0023] To better understand the technical solutions of the present invention, the present invention is described below using specific examples. It should be noted that the examples are merely further explanations of the present invention, and the applicable embodiments are not limited to the scope of the examples. The present invention is not limited thereto in any way. Those skilled in the art may make non-essential improvements and adjustments based on the contents of the above invention.

[0024] The contents not described in detail in the present specification belong to the common knowledge of professionals in the field. Unless otherwise specified, the raw materials and equipment used can be purchased from the market or are commonly used in the field.

[0025] The present invention proposes a method for enhancing biogas production by anaerobic digestion of food waste by regulating fatty acid metabolism using condiments, wherein the condiment used is piperine naturally remaining in the food waste.

[0026] This sample of food waste was collected from a student cafeteria. To simulate the presence of varying concentrations of piperine in food waste, the student cafeteria's food waste was free of piperine. The collected food waste was first sorted and crushed (1 mm) to remove impurities before being placed in an anaerobic digester. The inoculum sludge used in the experiment was obtained from an anaerobic digester operating in the laboratory.

[0027] Implementation 1

[0028] (1) In an anaerobic digestion reactor with a working volume of 333 mL, 300 mL of a mixture of food waste and excess sludge was added. Then, piperine was added to achieve a piperine concentration of 1 mg / g VS in the reaction system. After adding 33 mL of seed sludge, the pH value was adjusted to approximately 7.0 ± 0.1. After nitrogen stripping for 6 minutes, the digester was sealed and transferred to a constant temperature shaking incubator for anaerobic digestion and methane production. The reaction was terminated when methane production no longer increased.

[0029] (2) More specifically, the mass ratio of organic matter in the food waste and residual sludge in the mixed material is 1:1 to 1:2, and the pH value is 6 to 7. The temperature of the constant temperature shaking incubator is 35°C and the rotation speed is 150 rpm. The biogas production and fatty acid changes are regularly monitored.

[0030] Example 2

[0031] The operation method of this example is the same as that of Example 1, except that piperine is added to achieve a piperine concentration of 3 mg / g VS in the reaction system.

[0032] Comparative Example 1

[0033] The operation method of this comparative example is the same as that of Example 1, except that no piperine is added, so that the concentration of piperine in the fermentation reaction system is 0 mg / g VS.

[0034] Specifically, refer to Figure 1 Comparison of methane production rates in a reactor containing food waste treated with piperine versus a control group without piperine. When piperine was added at a dose of 1 mg / g VS, the experimental group achieved the highest cumulative methane production, a 35.3% increase compared to the control group, demonstrating that piperine significantly promotes methane production.

[0035] Specifically, refer to Figure 2 The following is a graph showing the changes in fatty acids in the anaerobic digestion systems of Example 2 and Comparative Example 1, respectively showing the dynamic changes in the contents of acetic acid, propionic acid, and valeric acid during the anaerobic co-digestion process. It can be seen from the figure that the addition of piperine can reduce the production of fatty acids, thereby making the anaerobic fermentation system more stable. The fermentation system is mainly composed of acetic acid and propionic acid. From a thermodynamic point of view, the Gibbs free energy of the reaction of propionic acid decomposing to produce acetic acid is positive, which means that the reaction is difficult to proceed spontaneously under standard conditions. By adding piperine, the content of fatty acids in the system can be effectively reduced, effectively promoting the conversion and utilization of acetic acid and propionic acid, providing new ideas for optimizing the anaerobic co-digestion process.

[0036] The above description is merely an example of the present invention and does not limit the scope of the present invention. The condiment is piperine, which may be derived from, but is not limited to, natural piperine extracted from food waste and synthetic piperine. The dosage of piperine is 0-3 mg / g VS of the volatile solids in the reactor. Any application, directly or indirectly, of the present invention's description and drawings to other related technical fields is also encompassed within the scope of the present invention.

Claims

1. A method for enhancing biogas production by anaerobic digestion of kitchen waste by regulating fatty acid metabolism using condiments, characterized in that: The steps include: S1. Identify and utilize piperine condiment in food waste, add excess sludge to food waste containing piperine, mix evenly, control the concentration of piperine in the mixture within a certain range, and adjust the pH value; S2. The mixed material treated in step S1 is fed into an anaerobic digestion reactor, and the biogas production and daily gas production are monitored to enhance the biogas production by anaerobic digestion of the food waste.

2. The method for enhancing biogas production by anaerobic digestion of kitchen waste by regulating fatty acid metabolism using piperine according to claim 1, characterized in that: In step S1, the food waste is sorted and crushed to a particle size of 1-5 mm. The total solid content (TS) is 58-100 g / L, of which volatile organic compounds (VS) account for more than 98% of the total solids.

3. The method for enhancing biogas production by anaerobic digestion of kitchen waste by regulating fatty acid metabolism using piperine according to claim 1, characterized in that: In step S1, the mass ratio of organic matter in the food waste and the residual sludge in the mixed material is 1:1 to 1:2, and the pH value is 6 to 7.

4. The method for enhancing biogas production by anaerobic digestion of kitchen waste by regulating fatty acid metabolism using piperine according to claim 1, characterized in that: In step S1, the concentration of piperine in the mixed material is 0-3 mg / g VS.

5. The method for enhancing biogas production by anaerobic digestion of kitchen waste by regulating fatty acid metabolism using piperine according to any one of claims 1 to 4, characterized in that: In step S2, when the anaerobic digestion reactor is started, anaerobic sludge needs to be inoculated, and the inoculation ratio is 9:1 to 4:

1.

6. The method for enhancing biogas production by anaerobic digestion of kitchen waste by regulating fatty acid metabolism using piperine according to any one of claims 1 to 5, characterized in that: In step S2, the temperature of the anaerobic digestion reactor is 30-37° C. and the pH is 6-8.

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