A method for improving anaerobic fermentation efficiency of organic waste

Abstract

The present invention relates to a method for improving the anaerobic fermentation efficiency of organic waste, which belongs to the technical field of waste resource recycling. The specific operation is to first crush the organic waste and mix it evenly to obtain an anaerobic fermentation substrate, then mix the white rot fungus fermentation product, cellulase and acetic acid sodium acetate buffer solution to obtain solution A, mix the organic metal framework material with solution A in a mass ratio of 2: 1 and stir thoroughly to obtain a complex, and finally vacuum freeze-dry the complex, and finally evenly mix the pretreated organic metal framework material with the anaerobic fermentation substrate and perform anaerobic fermentation, wherein the organic metal framework material is one of UiO-66 series, MOF-808 series and MIL-101 series. The method for improving anaerobic fermentation efficiency provided by the present invention adopts an anaerobic fermentation system including a catalyst, and when waste resources are reused by fermentation treatment, the PTA-MIL-101-Br included in the catalyst can effectively improve fermentation efficiency and methane output.

Description

Technical Field

[0001] The invention belongs to the technical field of waste resource recycling technology, and particularly relates to a method for improving the anaerobic fermentation efficiency of organic waste. Background Art

[0002] Anaerobic fermentation is an effective way to convert organic waste into bioenergy (such as methane) and stable biofertilizer. However, due to their complex structure and stability, macromolecular organic matter such as cellulose, hemicellulose, and protein in organic waste is often difficult for anaerobic microorganisms to directly utilize, which limits the efficiency of anaerobic fermentation and the quality of the product.

[0003] Due to their unique structure and properties, such as high specific surface area, tunable pore structure, and highly ordered crystal structure, metal organic frameworks (MOFs) offer uniform catalytic sites and exhibit enormous potential for application in catalysis. In biocatalysis, in particular, metal organic frameworks (MOFs) can serve as effective catalysts, accelerating chemical reactions and improving reaction rates and selectivity.

[0004] Currently, biocatalysts are the primary catalysts commonly used to increase anaerobic fermentation rates. However, biocatalysts are susceptible to inactivation by heat, chemicals, and bacteria, resulting in poor stability. Based on the shortcomings of existing anaerobic fermentation methods and the performance characteristics of metal-organic frameworks (MOFs), this paper proposes a method for improving the anaerobic fermentation efficiency of organic waste. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for improving the anaerobic fermentation efficiency of organic waste in order to solve the above problems.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] The present invention provides a method for improving the anaerobic fermentation efficiency of organic waste, comprising the following steps:

[0008] (1) Crush and mix the organic waste to obtain anaerobic fermentation substrate;

[0009] (2) The organic metal framework material is evenly mixed with the anaerobic fermentation substrate and then subjected to anaerobic fermentation.

[0010] As a further optimization solution of the present invention, the organic metal framework material is one of the UiO-66 series, MOF-808 series and MIL-101 series.

[0011] As a further optimization solution of the present invention, the organic metal framework material is one of UIO-66-NH2, MOF-808(Zr) and PTA-MIL-101-Br.

[0012] As a further optimization solution of the present invention, the organic metal framework material is PTA-MIL-101-Br.

[0013] As a further optimization scheme of the present invention, in step (2), the organic metal framework material is pretreated and then mixed with the anaerobic fermentation substrate. The specific operation of the pretreatment is: mixing the white rot fungus fermentation product, cellulase and acetic acid-sodium acetate buffer solution to obtain solution A, mixing the organic metal framework material and solution A at a mass ratio of 2:1 and fully stirring to obtain a composite, and finally performing a vacuum freeze-drying treatment on the composite.

[0014] As a further optimized solution of the present invention, in solution A, the mixing ratio of the raw materials is 200-350 ml of white rot fungus fermentation product and 300-500 ml of acetic acid-sodium acetate buffer solution per 300 ml of cellulase solution.

[0015] As a further optimization solution of the present invention, the mixing mass ratio of the organic metal framework material to the anaerobic fermentation substrate is (1-3):100.

[0016] As a further optimized solution of the present invention, the organic waste is one or more of crop straw, livestock and poultry manure, food processing waste and urban organic garbage.

[0017] As a further optimization solution of the present invention, the anaerobic fermentation efficiency specifically refers to methane production efficiency, output peak value and total output.

[0018] The beneficial effects of the present invention are:

[0019] This method for improving anaerobic fermentation efficiency achieves the effects of improving anaerobic fermentation efficiency and improving the quality of anaerobic fermentation products based on an anaerobic fermentation system containing PTA-MIL-101-Br. In this anaerobic fermentation system, on the one hand, PTA-MIL-101-Br itself can achieve a significant catalytic effect, effectively improving the methane production efficiency, peak output, and total output of the anaerobic fermentation system. On the other hand, PTA-MIL-101-Br also acts as a carrier for a mixture of white rot fungal fermentation products, cellulase, and acetic acid-sodium acetate buffer solution, which helps to improve the uniformity of the catalyst distribution in the anaerobic fermentation substrate, further enhancing the effectiveness of the catalyst in the anaerobic fermentation system, and achieving a more efficient and higher-yield anaerobic fermentation effect. DETAILED DESCRIPTION

[0020] The present application is described in further detail below. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0021] 1. Materials

[0022] Unless otherwise specified, the methods used in the present invention are conventional methods known to those skilled in the art, and the reagents and other materials used are commercially available products unless otherwise specified.

[0023] The preparation method of PTA-MIL-101-Br in the present invention comprises: mixing 2 mmol of FeCl3·6H2O, 1 mmol of 2-bromoterephthalic acid, 1 mmol of terephthalic acid, and 0.08 mmol of phosphotungstic acid into a DMF solution, heating the mixture for 16 hours at 110°C using a one-pot method, separating a solid product using a centrifuge, washing the solid product with a DMF solution at room temperature, and then vacuum drying the washed solid product at 80°C to obtain PTA-MIL-101-Br.

[0024] The mass fraction of cellulase in the cellulase solution used is 1%, and it is prepared before use.

[0025] The concentration of acetic acid-sodium acetate buffer used was 0.05 mol / L and pH 4.3;

[0026] The method for preparing the white rot fungus fermentation product is as follows: inoculating the white rot fungus (specifically, Phanerochaete chrysosporium) into a fermentation medium for full fermentation, filtering the fermentation product, and using the filtrate as the white rot fungus fermentation product, wherein the fermentation medium comprises 2 g / L of glucose, 40 g / L of wheat bran, 1 g / L of urea, 3 g / L of (NH4)2SO4, 2 g / L of peptone, 3 g / L of KH2PO4, 0.4 g / L of CaCl2, 0.01 g / L of FeSO4, and 0.004 g / L of MnSO4, with the balance being water;

[0027] The UIO-66-NH2 used was purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., and MOF-808 (Zr) was purchased from Xi'an Qiyue Biological.

[0028] 2. Methods

[0029] 1. Effect of organic metal framework materials on anaerobic fermentation efficiency Example

[0030] (1) 30 g of straw and 30 g of pig manure were crushed and evenly mixed, and then added into 500 ml of sterile water and further mixed to obtain an anaerobic fermentation substrate;

[0031] (2) PTA-MIL-101-Br and anaerobic fermentation substrate were uniformly mixed at a mass ratio of 1:100 and then anaerobic fermentation was carried out at a fermentation temperature of 30°C.

[0032] The anaerobic fermentation system obtained in Example 1 is marked as A. Based on the method of Example 1, anaerobic fermentation systems B and C are prepared. The only difference is that UIO-66-NH2 and MOF-808(Zr) are used in place of PTA-MIL-101-Br as the selected organic metal materials.

[0033] Blank example

[0034] 30 g of straw and 30 g of pig manure were crushed and evenly mixed, and then added into 500 ml of sterile water and further mixed to obtain an anaerobic fermentation substrate, which was then subjected to anaerobic fermentation at a fermentation temperature of 30°C.

[0035] The fermentation process of fermentation systems AC in Example 1 and the anaerobic fermentation system in the blank example was monitored. The specific monitoring method was to collect the gas produced during the fermentation process every 5 days during the 90-day fermentation period and measure the methane content therein using a gas chromatograph. The results are shown in the following table:

[0036] ;

[0037] From the table above we can see that:

[0038] In Example 1, the total amount of gas and methane production produced by fermentation systems A, B, and C are better than those of the blank example, and the speed of reaching the peak gas production is faster. When the gas production reaches the peak, the methane production in the gas is also higher. This result shows that the use of organic metal framework materials such as UIO-66-NH2, MOF-808 (Zr) and PTA-MIL-101-Br can improve the anaerobic fermentation efficiency of organic waste and increase the proportion of methane in the gas fermentation product. Further comparison of the corresponding data of A, B, and C shows that compared with UIO-66-NH2 and MOF-808 (Zr), PTA-MIL-101-Br can further prolong the duration of the gas production peak, which is conducive to further increasing the methane output, and comprehensively achieving the effect of improving the methane production efficiency, output peak and total output during the anaerobic fermentation process.

[0039] 2. Effect of solution A on anaerobic fermentation efficiency Example

[0040] (1) 30 g of straw and 30 g of pig manure were crushed and evenly mixed, and then added into 500 ml of sterile water and further mixed to obtain an anaerobic fermentation substrate;

[0041] (2) Pretreatment of PTA-MIL-101-Br: 200 ml of white rot fungus fermentation product, 300 ml of cellulase solution, and 500 ml of acetic acid-sodium acetate buffer solution were mixed to obtain solution A. PTA-MIL-101-Br and solution A were mixed at a mass ratio of 2:1 and stirred thoroughly to obtain a composite. Finally, the composite was subjected to vacuum freeze-drying treatment for 24 h at a treatment temperature of 35°C.

[0042] (3) The pretreated PTA-MIL-101--Br was evenly mixed with the anaerobic fermentation substrate at a mass ratio of 3:100 and then subjected to anaerobic fermentation at a fermentation temperature of 30°C.

[0043] The anaerobic fermentation system obtained in Example 2 was labeled D. Based on the method of Example 2, an anaerobic fermentation system E was prepared, except that the raw material composition of solution A in step (2) was adjusted to: 350 ml of white rot fungus fermentation product, 300 ml of cellulase solution, and 300 ml of acetic acid-sodium acetate buffer solution;

[0044] Based on the method of Example 2, anaerobic fermentation systems F and G were prepared, with the only difference being that UIO-66-NH2 and MOF-808(Zr) were used in turn instead of PTA-MIL-101-Br as the selected organometallic materials.

[0045] Comparative Example 1

[0046] 200 ml of white rot fungus fermentation product, 300 ml of cellulase solution and 500 ml of acetic acid-sodium acetate buffer solution were mixed to obtain solution A, which was vacuum freeze-dried for 24 hours at a temperature of 35°C. The product obtained after freeze-drying was uniformly mixed with an anaerobic fermentation substrate at a mass ratio of 3:100 and then anaerobic fermentation was carried out at a fermentation temperature of 30°C.

[0047] The fermentation process of the fermentation system DG in Example 2 and the anaerobic fermentation system in Comparative Example 1 was monitored. The specific monitoring method was to collect the gas produced during the fermentation process every 5 days during the 90-day fermentation period and measure the methane content therein using a gas chromatograph. Based on the obtained data, the gas emission pattern and methane production pattern during the 90-day fermentation period were further calculated. The results are shown in the following table:

[0048] ;

[0049] Based on the data in the above table, the following conclusions are drawn:

[0050] 1. Compared with fermentation system A in Example 1, D and F in Example 2 respectively introduced solution A of different components into the fermentation system based on A, while F and G introduced solution A of the same components into the fermentation system based on B and C, respectively. Both of these made the fermentation system produce gas more efficiently, with higher peak output and total output. Correspondingly, the methane production efficiency, peak output, and total output were also better. This result shows that the introduction of solution A into the fermentation system based on the existing organic metal framework material can further improve the efficiency of anaerobic fermentation;

[0051] 2. In Example 2, the difference between D, E, and F lies in the different organic metal framework materials used. By comparing the data of each group, it can be seen that when PTA-MIL-101-Br is used in combination with solution A, the best anaerobic fermentation effect can be obtained. Not only is the fermentation efficiency higher, the total gas output and methane output are more, and the proportion of methane in the output gas is significantly higher. Further running through the data of Comparative Example 1, the difference between Comparative Example 1 and the blank example is that the fermentation system of Comparative Example 1 is supplemented with solution A (the components are the same as solution A in D, F, and G). The results show that when only solution A is introduced into the fermentation system, it only has the effect of increasing the amount of gas output by fermentation. Comprehensive analysis shows that the combination of PTA-MIL-101-Br and solution A can effectively increase the proportion of methane in the gas produced by fermentation.

[0052] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A method for improving the anaerobic fermentation efficiency of organic waste, characterized in that: The following steps are involved: (1) Crush and mix the organic waste to obtain anaerobic fermentation substrate; (2) uniformly mixing the pretreated organic metal framework material with the anaerobic fermentation substrate and then performing anaerobic fermentation to improve the anaerobic fermentation efficiency of the organic waste, specifically including the improvement of methane production efficiency, output peak, total output, and the proportion of methane in the output gas; The organic metal framework material is PTA-MIL-101-Br; The specific operation of the pretreatment is: mixing the white rot fungus fermentation product, cellulase and acetic acid-sodium acetate buffer solution to obtain solution A, mixing the organic metal framework material and solution A at a mass ratio of 2:1 and fully stirring to obtain a composite, and finally performing a vacuum freeze-drying treatment on the composite; The preparation method of the white rot fungus fermentation product comprises the following steps: inoculating the white rot fungus into a fermentation medium and fully fermenting the culture medium, filtering the fermentation product, and using the filtrate as the white rot fungus fermentation product.

2. The method for improving the anaerobic fermentation efficiency of organic waste according to claim 1, characterized in that: In the solution A, the mixing ratio of the raw materials is 200-350 ml of white rot fungus fermentation product and 300-500 ml of acetic acid-sodium acetate buffer solution per 300 ml of cellulase solution.

3. The method for improving the anaerobic fermentation efficiency of organic waste according to claim 1, characterized in that: The mixing mass ratio of the organic metal framework material to the anaerobic fermentation substrate is (1-3):

100.

4. The method for improving the anaerobic fermentation efficiency of organic waste according to claim 1, characterized in that: The organic waste is one or more of crop straw, livestock and poultry excrement, food processing waste and urban organic waste.