CN113736831A

CN113736831A - Method for processing edible fungus dregs and application thereof

Info

Publication number: CN113736831A
Application number: CN202111142875.1A
Authority: CN
Inventors: 汤晓玉; 高雄辉; 高春林; 赵昆炀; 王霜
Original assignee: Xihua University
Current assignee: Xihua University
Priority date: 2021-09-28
Filing date: 2021-09-28
Publication date: 2021-12-03

Abstract

The invention relates to the technical field of fungus dreg treatment, and discloses a treatment method of edible fungus dreg, which comprises the following steps: s1, performing anaerobic digestion on edible fungus residues, and respectively collecting biogas and digestion residues generated in the anaerobic digestion process; s2, sequentially centrifuging, drying and washing the digestion residues until sugar and protein adsorbed by the digestion residues are removed to obtain washing residues; s3, carrying out reflux extraction on the washing residues to obtain a mixture; s4, sequentially carrying out centrifugation and solid-liquid separation on the mixture to obtain an extracting solution and extraction residues; s5, sequentially concentrating, precipitating, centrifuging and carrying out solid-liquid separation on the extracting solution to obtain the solid lignin. According to the invention, by utilizing a composite process of anaerobic digestion and reflux extraction, firstly, the edible fungus residues are subjected to anaerobic digestion to produce biogas and enrich lignin, and then the reflux extraction is utilized to purify lignin and remove impurities such as protein and ash, so that the effects of reducing the treatment difficulty of anaerobic fermentation residues and recovering high-quality lignin are achieved.

Description

Method for processing edible fungus dregs and application thereof

Technical Field

The invention relates to the technical field of fungus dreg treatment, in particular to a treatment method of edible fungus dreg and application thereof.

Background

The edible fungus residue is a waste culture medium left after fruiting bodies are harvested in the edible fungus culture process, mainly comprises mycelium and degraded lignocellulose, contains a large amount of crude fibers, polysaccharides and other components, and also contains abundant mycelium proteins, amino acids, carbohydrates, trace elements and the like, and has high research and utilization values. At present, the utilization rate of the edible fungus residues and fungus residues in China is low, most of the edible fungus residues and fungus residues are randomly discarded or incinerated except part of the edible fungus residues and fungus residues are utilized in modes of secondary cultivation, composting, animal feed and the like, so that resources cannot be effectively utilized, and the pollution to the surrounding environment cannot be ignored. Therefore, the reasonable development and utilization of the edible fungus residues can not only open up resources to change waste into valuable, but also have obvious ecological benefit.

The mushroom dregs are mainly sawdust, cottonseed hulls, straw and the like, so the mushroom dregs can be regarded as a lignocellulose mixture. Except that in the production of edible fungi, these lignocelluloses are also biodegraded by white rot fungi. Therefore, the edible fungus dregs are very suitable for the degradation and absorption of microorganisms and are ideal raw materials for biogas fermentation. The biogas produced by using the edible fungus residues not only can relieve the dependence on fossil fuels at present, but also can reduce the emission of greenhouse gases, and has obvious environmental effect. However, the direct use of the edible fungi residues as fermentation raw materials still has the problems of low methane yield of the biogas and difficult treatment of a large amount of anaerobic fermentation residues, and the problems become bottlenecks for restricting the technical development.

Therefore, a method for treating edible fungus residues is needed to achieve the effects of improving the gas production rate of the biogas and reducing the treatment difficulty of the anaerobic fermentation residues.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for treating edible fungus residues and application thereof, which at least achieve the effects of reducing the treatment difficulty of anaerobic fermentation residues and recovering high-quality lignin.

The purpose of the invention is realized by the following technical scheme:

on the one hand, the method for processing the edible fungus dregs is provided. The processing method comprises the following steps:

s1, carrying out anaerobic digestion on the edible fungus residues, and respectively collecting biogas and digestion residues generated in the anaerobic digestion process;

s2, sequentially centrifuging, drying and washing the digestion residues until sugar and protein adsorbed by the digestion residues are removed to obtain washing residues;

s3, carrying out reflux extraction on the washing residues to obtain a mixture; wherein the extractant adopted by the reflux extraction comprises at least one of ethanol, isopropanol, formic acid, acetic acid, gamma-valerolactone and water;

s4, sequentially carrying out centrifugation and solid-liquid separation on the mixture to obtain an extracting solution and extraction residues;

and S5, sequentially concentrating, precipitating, centrifuging and carrying out solid-liquid separation on the extracting solution to obtain the solid lignin.

In the above embodiment, by using the composite process of anaerobic digestion and reflux extraction, the edible fungus residue is first subjected to anaerobic digestion to produce biogas and enrich lignin, and then the washed residue obtained by washing the digestion residue is subjected to reflux extraction to purify lignin and remove impurities such as protein and ash, so that the treatment difficulty of anaerobic fermentation residue is reduced and high-quality lignin is recovered.

In some embodiments, in S3, the extractant used in the reflux extraction is a mixture of at least one of the ethanol, the isopropanol, the formic acid, the acetic acid, and the gamma valerolactone and the water.

In some embodiments, in S3, the reflux extraction employs an extractant that is a mixture of the at least one of ethanol and isopropanol, the at least one of formic acid and acetic acid, and the water.

In some embodiments, in S3, the extractant used for the reflux extraction is a mixture of the water and at least one of the formic acid and the acetic acid.

In some of the above embodiments, the extraction agent with multiple phases (including an aqueous phase and an organic phase) is used for reflux extraction, and the organic phase in the extraction agent interacts with the lignin in the water washing residue, and the aqueous phase in the extraction agent further accelerates the interaction between the organic phase and the lignin, so as to achieve the effect of obtaining lignin with higher yield and higher purity.

It should be noted that the ratio of aqueous phase to organic phase does not greatly affect the extraction efficiency, since lignin is a lipophilic polymer that is immiscible with water.

In some embodiments, in S3, the extractant used for the reflux extraction is a mixture of the gamma valerolactone and the water. Illustratively, the volume ratio of the gamma valerolactone to the water is 2: 1.

In some of the above embodiments, the extraction yield of lignin can be further increased by using the mixture of the gamma valerolactone and the water as an extracting agent. The reason is that the ester group in the gamma-valerolactone is a large polar functional group and can have strong interaction force with lignin; more importantly, ester groups in the gamma-valerolactone can react with lignin to degrade the lignin, so that the physical properties and the solubility of the lignin are changed, and the extraction effect is obviously improved.

In some embodiments, S3 further includes a step of drying, grinding and screening the water washing residue to obtain the extract before the reflux extraction.

In some embodiments, in S3, the temperature of the reflux extraction is 90-110 ℃, and the time of the reflux extraction is 24 h.

In some embodiments, the weight to volume ratio of the extract to the extractant in S3 is 1:20(g: mL).

In some embodiments, in S3, the drying temperature is 80 ℃ and the drying time is 48 h.

In some embodiments, in S3, the sieving is through an 80 mesh sieve.

In some embodiments, in S1, the anaerobic digestion is to mix the edible fungus dregs, the livestock manure and the inoculum sufficiently to obtain a mixture, and to ferment the mixture under anaerobic conditions until no gas is produced.

In some embodiments, the livestock manure comprises at least one of chicken manure, cattle manure, and pig manure.

In some embodiments, the edible fungus residues and the livestock manure are mixed and fermented to produce a synergistic effect, so that the effect of remarkably improving the accumulated yield of methane is achieved.

In some embodiments, the inoculum is anaerobic fermentation digested sludge; and/or the mass ratio of volatile solids in the edible fungus residues to volatile solids in the livestock and poultry manure is (1-2) to (1-2); and/or the mass of the volatile solid in the inoculum accounts for 30% of the total mass of the volatile solid in the edible fungus residues and the volatile solid in the livestock manure; and/or the solid content of the mixture is 10-15 wt%; and/or the fermentation is medium-temperature fermentation or high-temperature fermentation; wherein the fermentation temperature of the medium-temperature fermentation is 30-40 ℃, and the fermentation temperature of the high-temperature fermentation is 50-60 ℃; and/or the pH value of the fermentation is 6.8-7.2.

In some of the above embodiments, by limiting the solid content of the mixture, the accumulation of Volatile Fatty Acids (VFA) in the anaerobic digestion can be controlled, and on this basis, by limiting the mass ratio of volatile solids in the edible mushroom dregs to volatile solids in the poultry and livestock manure, the C/N ratio of the mixture can be adjusted, thereby improving the stability of the fermentation process.

In some embodiments, the method further comprises the step of culturing the anaerobic fermentation digested sludge at 35 ℃ until no gas is produced before the edible fungi residue, the livestock manure and the anaerobic fermentation digested sludge are fully mixed.

In some embodiments, in S2, the rotation speed of the centrifugation is 3500-4500 rpm, and the time is 10-20 min.

In some embodiments, the water washing comprises the steps of washing, centrifuging, and solid-liquid separating, in this order, in S2. Illustratively, the rotation speed of the centrifugation is 4000rpm, and the time of the centrifugation is 30 min.

In some embodiments, the number of water washes is at least three in S2. Illustratively, the number of water washes is three.

In some embodiments, in S4, the rotation speed of the centrifugation is 10000rpm, and the time of the centrifugation is 10 min.

In some embodiments, in S5, before the extracting solution is sequentially concentrated, precipitated, centrifuged, and solid-liquid separated, the method further comprises the steps of washing the raffinate with the extractant to obtain a washing solution, and mixing the washing solution with the extracting solution.

In some embodiments, in S5, the precipitating is performed by mixing the concentrated solution obtained by concentrating with deionized water to precipitate lignin.

In some embodiments, in S5, the rotation speed of the centrifugation is 12000rpm, and the time of the centrifugation is 20 min.

In some embodiments, the edible mushroom pomace comprises Auricularia polytricha pomace.

In another aspect, there is provided the use of a treatment as described in any one of the above examples for producing biogas and/or extracting lignin.

The invention has the beneficial effects that:

1. according to the method for treating the edible fungus residues, disclosed by the invention, by utilizing the composite process of anaerobic digestion and reflux extraction, the edible fungus residues are subjected to anaerobic digestion to produce biogas and enrich lignin, and then the reflux extraction is utilized to purify the lignin and remove impurities such as protein and ash, so that the effects of reducing the treatment difficulty of anaerobic fermentation residues and recovering high-quality lignin are achieved.

2. According to the method for treating the edible fungus residues, the edible fungus residues and the livestock manure are mixed and fermented to generate a synergistic effect, so that the effect of remarkably improving the accumulated yield of methane is achieved.

Drawings

FIG. 1 is a graph comparing the cumulative methane production during anaerobic fermentation in examples 1-9 and a control group;

FIG. 2 is a graph comparing the maximum methane content during anaerobic fermentation in examples 1-9 and a control;

FIG. 3 is a graph showing the change of the content of volatile acids in the anaerobic fermentation processes in examples 1 to 9;

FIG. 4 is a graph comparing the extraction yields of lignin in examples 10 to 16.

Detailed Description

The technical solutions in some embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments provided by the present invention belong to the protection scope of the present invention.

Throughout the specification and claims, the term "comprising" is to be interpreted in an open, inclusive sense, i.e., as "including, but not limited to," unless the context requires otherwise. In the description herein, the terms "some embodiments," "examples," and the like are intended to indicate that a particular feature, structure, material, or characteristic described in connection with the embodiments or examples is included in at least one embodiment or example of the invention. The schematic representations of the above terms are not necessarily referring to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be included in any suitable manner in any one or more embodiments or examples.

Hereinafter, the terms "at least one of A, B and C" have the same meaning as "A, B or at least one of C," each including the following combination of A, B and C: a alone, B alone, C alone, a and B in combination, a and C in combination, B and C in combination, and A, B and C in combination.

The term "a and/or B" includes the following three combinations: a alone, B alone, and a combination of A and B.

Example 1

A method for carrying out anaerobic digestion on edible fungus dregs comprises the following steps:

fully mixing 14.0g of edible fungus residues, 50.6g of fresh chicken manure and 46.3g of straw anaerobic fermentation digested sludge to obtain a mixture with a solid content (TS) of 10 wt%, adding the mixture into a fermentation bottle, adding a proper amount of water to adjust the fermentation volume to 350mL, adjusting the pH value to 7.0 by using 1M HCl or 1M NaOH, introducing nitrogen for 3min to remove air in the fermentation bottle, finally sealing the fermentation bottle, performing anaerobic fermentation at 35 ℃ until no gas is produced, and respectively collecting methane and digestion residues produced in the anaerobic fermentation process.

Wherein, the mass of Volatile Solid (VS) is counted, the edible fungus residue (SMS) is fresh Chicken Manure (CM) is 1: 2;

the inoculum accounts for 30 percent of the total mass of the edible fungus residues and the fresh chicken manure by the mass of the contained Volatile Solid (VS);

the edible fungus residues are taken from yellow back fungus residues of yellow back fungus planting bases of \37025, Haoyang agricultural development Limited company, taken back, naturally air-dried and crushed by a crusher for later use; the raw material substrate for producing the yellow back fungus mainly comprises wood chips, corncobs, corn flour, lime and the like;

fresh chicken manure is taken from a farm nearby Shuangliu county and is stored in a refrigerator at the temperature of-20 ℃ for later use;

the inoculum is prepared by taking straw anaerobic fermentation digested sludge from double-flow base of biogas science research institute of Ministry of agriculture, taking back the sludge, storing in a 4 ℃ closed barrel, culturing at 35 ℃ for about 7 days before use until no gas is produced, and inoculating into a fermentation bottle.

Example 2

The present embodiment is different from embodiment 1 in that: fully mixing 19.0g of edible fungus residues, 34.5g of fresh chicken manure and 42.1g of straw anaerobic fermentation digested sludge; wherein, the mass of Volatile Solid (VS) is counted, the mass of the edible fungus dreg (SMS) and the mass of the fresh Chicken Manure (CM) are 1: 1. The remaining steps and conditions of this example were the same as in example 1.

Example 3

The present embodiment is different from embodiment 1 in that: fully mixing 23.2g of edible fungus residues, 21.1g of fresh chicken manure and 38.6g of straw anaerobic fermentation digested sludge; wherein, the mass of Volatile Solid (VS) is counted, the mass of the edible fungus dreg (SMS) and the mass of the fresh Chicken Manure (CM) are 2: 1. The remaining steps and conditions of this example were the same as in example 1.

Example 4

fully mixing 11.9g of edible fungus residues, 66.4g of fresh pig manure and 39.6g of straw anaerobic fermentation digested sludge to obtain a mixture with a solid content (TS) of 10 wt%, adding the mixture into a fermentation bottle, adding a proper amount of water to adjust the fermentation volume to 350mL, adjusting the pH value to 7.0 by using 1M HCl or 1M NaOH, introducing nitrogen for 3min to remove air in the fermentation bottle, finally sealing the fermentation bottle, performing anaerobic fermentation at 35 ℃ until no gas is produced, and respectively collecting methane and digestion residues produced in the anaerobic fermentation process.

Wherein, the mass of Volatile Solid (VS) is counted, the edible fungus residue (SMS) is that fresh Pig Manure (PM) is 1: 2;

the inoculum accounts for 30 percent of the total mass of the edible fungus residues and the fresh pig manure by the mass of the contained Volatile Solid (VS);

fresh pig manure is taken from a farm nearby Shuangliu county and is stored in a refrigerator at the temperature of-20 ℃ for later use;

Example 5

This embodiment is different from embodiment 4 in that: fully mixing 17.0g of edible fungus residues, 47.5g of fresh pig manure and 37.8g of straw anaerobic fermentation digested sludge; wherein, the mass of the Volatile Solid (VS) is counted, the mass of the edible fungus dreg (SMS) and the mass of the fresh Pig Manure (PM) are 1: 1. The remaining steps and conditions of this example were the same as in example 4.

Example 6

This embodiment is different from embodiment 4 in that: fully mixing 21.8g of edible fungus residues, 30.2g of fresh pig manure and 35.9g of straw anaerobic fermentation digested sludge; wherein, the mass of the Volatile Solid (VS) is counted, the mass of the edible fungus dreg (SMS) and the mass of the fresh Pig Manure (PM) are 2: 1. The remaining steps and conditions of this example were the same as in example 4.

Example 7

fully mixing 12.3g of edible fungus residues, 51.7g of fresh cow dung and 41.0g of straw anaerobic fermentation digested sludge to obtain a mixture with a solid content (TS) of 10 wt%, adding the mixture into a fermentation bottle, adding a proper amount of water to adjust the fermentation volume to 350mL, adjusting the pH value to 7.0 by using 1M HCl or 1M NaOH, introducing nitrogen for 3min to remove air in the fermentation bottle, finally sealing the fermentation bottle, performing anaerobic fermentation at 35 ℃ until no gas is produced, and respectively collecting methane and digestion residues produced in the anaerobic fermentation process.

Wherein, the mass of Volatile Solid (VS) is counted, the edible fungus dreg (SMS) and the fresh cow Dung (DM) are 1: 2;

the inoculum accounts for 30 percent of the total mass of the edible fungus residues and the fresh cow dung by the mass of the contained Volatile Solid (VS);

fresh cow dung is taken from a farm nearby Shuangliu county and is stored in a refrigerator at the temperature of-20 ℃ for later use;

Example 8

This embodiment is different from embodiment 7 in that: fully mixing 17.4g of edible fungus residues, 36.6g of fresh cow dung and 38.7g of straw anaerobic fermentation digested sludge; wherein, the mass of Volatile Solid (VS) is counted, the edible fungus dreg (SMS) and the fresh cow Dung (DM) are 1: 1. The remaining steps and conditions of this example were the same as in example 7.

Example 9

This embodiment is different from embodiment 7 in that: fully mixing 22.0g of edible fungus residues, 23.2g of fresh cow dung and 36.8g of straw anaerobic fermentation digested sludge; wherein, the mass of Volatile Solid (VS) is counted, the mass of the edible fungus dreg (SMS) and the mass of the fresh chicken manure (DM) are 2: 1. The remaining steps and conditions of this example were the same as in example 7.

Example 10

A method of treating digestion residues, comprising the steps of:

1) centrifuging the digestion residue obtained in the embodiment 4 at the rotating speed of 4000rpm for 10min, drying the solid obtained by centrifuging, and then washing with water for 3 times to remove the adsorbed sugar and protein to obtain washing residue; wherein, each time of water washing sequentially comprises the steps of washing, centrifuging for 30min at the rotating speed of 4000rpm and solid-liquid separation;

2) drying 10g +/-0.01 g of washing residue at the temperature of 80 ℃ for 48h, grinding and sieving by a 80-mesh sieve to obtain an extract to be extracted;

3) mixing the extract with an extractant, and performing reflux extraction at 100 ℃ for 24 hours to obtain a mixture; wherein the weight-volume ratio of the extract to be extracted to the extracting agent is 1:20(g: mL); the extractant is a mixture of gamma-valerolactone and water, and the mass ratio of the gamma-valerolactone to the water is 2: 1;

4) centrifuging the mixture at 10000rpm for 10min, and performing solid-liquid separation to obtain an extracting solution and extraction residues;

5) washing the extraction residue with an extractant to obtain a washing solution; mixing the washing solution with the extracting solution and concentrating to 50mL to obtain a concentrated solution; mixing the concentrated solution with 250mL of deionized water to precipitate lignin, centrifuging at 12000rpm for 20min, and performing solid-liquid separation to obtain solid lignin;

6) and (3) freezing the solid lignin in a refrigerator at the temperature of-80 ℃ for 1h, and drying in a freeze drying oven for 24h to obtain the dry lignin.

Example 11

The present embodiment is different from embodiment 10 in that: the extractant is a mixture of gamma-valerolactone and water, and the mass ratio of the gamma-valerolactone to the water is 1: 1. The remaining steps and conditions of this example were the same as in example 10.

Example 12

The present embodiment is different from embodiment 10 in that: the extractant is a mixture of acetic acid, formic acid and water, and the mass ratio of the acetic acid to the formic acid to the water is 3:5: 2. The remaining steps and conditions of this example were the same as in example 10.

Example 13

The present embodiment is different from embodiment 10 in that: the extractant is a mixture of acetic acid, formic acid and water, and the mass ratio of the acetic acid to the formic acid to the water is 4:5: 1. The remaining steps and conditions of this example were the same as in example 10.

Example 14

The present embodiment is different from embodiment 10 in that: the extracting agent is a mixture of isopropanol, formic acid and water, and the mass ratio of the isopropanol, the formic acid and the water is 3:5: 2. The remaining steps and conditions of this example were the same as in example 10.

Example 15

The present embodiment is different from embodiment 10 in that: the extracting agent is a mixture of isopropanol, formic acid and water, and the mass ratio of the isopropanol, the formic acid and the water is 4:5: 1. The remaining steps and conditions of this example were the same as in example 10.

Example 16

The present embodiment is different from embodiment 10 in that: the extractant is a mixture of formic acid and water, and the mass ratio of the formic acid to the water is 2: 1. The remaining steps and conditions of this example were the same as in example 10.

Control group

The method of the invention in example 1 was used for comparison with a control group, wherein the control group differs from example 1 in that: only the edible fungus residues and the anaerobic fermentation digested sludge of the straws are fully mixed, and fresh chicken manure is not added; other conditions such as selection and amount of remaining materials and other process steps are the same as in example 1 of the present invention.

It is noted that the TS and VS values for the edible fungi residues, the livestock manure and the inoculum mentioned in examples 1-9 and the control were measured according to standard methods (APHA et al, 1998): weighing the mass m of the crucible₁Taking about 2g of sample in a crucible with the weight m₂Drying at 105 deg.C for 8 hr, cooling to room temperature, weighing₃Then placing the mixture in a muffle furnace to be burnt for 2 hours at the temperature of 600 ℃, cooling the mixture to room temperature, and weighing m₄And calculating TS and VS by formulas.

Test effects

1. In order to verify the improvement of the potential of the treatment method for producing the biogas, the following operations are respectively carried out in the anaerobic fermentation processes of the embodiments 1 to 9 and the control group: during the fermentation process, the fermentation flask was manually shaken 2 times a day to mix the raw materials; the volume of biogas produced was measured by displacement and analyzed for biogas composition at regular intervals daily, and liquid samples were taken every three days for analysis of volatile acid (VFA) concentration.

1) And (3) determination of biogas components: the gas volume is measured by a drainage method, and the methane component is measured by a gas chromatograph PANNA-A60. The detector is a TCD detector, the chromatographic column is a carbon molecular sieve TDX-01, and the inner diameter is 3mm multiplied by 3 mm; the temperatures of the column box, the sample injector and the detector are respectively 180 ℃, 100 ℃ and 200 ℃; the carrier gas was hydrogen and the flow rate was 38mL/min (results are shown in FIGS. 1-2).

As can be seen from the figures 1-2, the accumulated methane yield and the maximum methane content of the edible fungus residues mixed and fermented with the fresh chicken manure, the fresh pig manure and the fresh cow manure are all obviously higher than those of the single fungus residues. From the point of accumulated methane yield, the edible fungus residues respectively have synergistic effect when being mixed and fermented with fresh chicken manure, fresh cow manure and fresh pig manure; wherein, the methane production potential of the mixed fermentation of the edible fungus dregs and the fresh chicken manure is higher than that of the fresh pig manure and the fresh cow manure. In addition, under the same TS condition, the accumulated methane yield is gradually increased along with the increase of the livestock manure proportion, but the lag phase is gradually prolonged.

2) Determination of volatile fatty acids: to a sample of the fermentation broth, 50. mu.L of formic acid was added for treatment to remove impurities such as proteins, followed by centrifugation at 13000rpm for 7 minutes, and the resulting supernatant was collected and filtered through a 0.22 μm membrane syringe filter. Analyzing volatile fatty acid by gas chromatograph (GC112N), wherein the detector is FID detector, the chromatographic column is water acid analytical column, and the inner diameter of the size is 2m multiplied by 2 mm; the temperatures of the column box, the sample injector and the detector are 180 ℃, 210 ℃ and 230 ℃ respectively; the carrier gas is nitrogen, and the flow rate is 75 mL/min; the amount of sample was 1. mu.L (results are shown in FIG. 3).

As can be seen from FIG. 3, in the mixed fermentation process, under the same TS conditions, the accumulation of VFA is reduced along with the increase of the proportion of the livestock manure, which indicates that the C/N ratio of the mixed material can be adjusted by adding the livestock manure, thereby improving the stability of the fermentation process.

2. In order to verify the effect of the treatment method of the present invention on lignin extraction, the lignin extraction yield in examples 10 to 16 was measured. The extraction yield of lignin (mass of dried lignin/mass of lignin in the digestion residue) x 100% (the result is shown in fig. 4).

As can be seen from FIG. 4, different extractants have different acting forces on lignin extraction, and the extractants have different capacities of entering into the lignin macromolecular chains, resulting in different extraction rates of the different extractants. In particular, a mixture of formic acid and water, a mixture of gamma-valerolactone and water, a mixture of acetic acid, formic acid and water and a mixture of isopropanol, formic acid and water have higher extraction yield. The reason is that ester groups are large-polarity functional groups and can have strong interaction force with lignin, more importantly, the ester groups in the gamma-valerolactone can react with the lignin, so that the lignin is degraded, the physical properties are changed, the solubility is changed along with the change of the physical properties, and the extraction effect is obviously improved. Alcohols and acids, although they can also strongly interact with lignin, cannot change the original physical properties of lignin, and therefore have lower extraction rates than gamma-valerolactone. On the other hand, the ratio of water to organic solvent does not greatly affect the extraction effect, because lignin is a lipophilic polymer and is not miscible with water, and the water mainly plays a role in accelerating the interaction between lignin and organic solvent.

3. In order to further verify the effect of the treatment method of the present invention on lignin extraction, the lignin of examples 10 to 16 was subjected to principal component analysis to determine the content of carbohydrates, acid-insoluble lignin and ash therein, respectively, by referring to the standard method established by the National Renewable Energy Laboratory (NREL) (slave et al, 2008 a; slave et al, 2005; slave et al, 2008 b). The results are shown in the following table:

group of	Dextran%	Xylan%	Arabinosan%	Carbohydrate%	Lignin%	Ash content%
							Example 10	1.89	1.89	0.84	4.62	9.83	46.00
Example 11	1.87	1.87	0.73	4.47	10.86	42.61
							Example 12	1.71	1.11	0.00	2.82	85.71	1.76
Example 13	1.58	1.30	0.40	3.28	93.90	0.77
							Example 14	0.43	0.54	0.00	0.97	83.46	6.67
Example 15	0.40	0.64	0.12	1.16	80.63	7.56
							Example 16	1.55	0.71	0.39	2.65	62.86	12.71

By analyzing the purity of the obtained lignin from the perspective of carbohydrates, lignin and ash in combination with the above table, it can be seen that:

the purity of the lignin obtained in example 13 is highest, the lignin content is 93.90%, the carbohydrate content is 3.28%, and the ash content is only 0.77%, and then in examples 12 and 14-15, which shows that the acid-acid or alcohol-acid mixed multiphase extractant can significantly improve the purity of the lignin. In addition, it can be seen from fig. 4 that the lignin yield of examples 10 to 11 is the highest, but it can be noted from the above table that the lignin purity of examples 10 to 11 is only 9.83% to 10.86%, the purity is much lower than that of the lignin obtained in other examples, and the ash content impurity is 42.61% to 46.00%. The reason is that gamma-valerolactone degrades lignin, increases the solubility of lignin, improves the yield, generates a mixture with a large amount of impurities, and is not favorable for high-value utilization of the obtained lignin.

In conclusion, the treatment method and the application of the edible fungus residues achieve the effects of reducing the treatment difficulty of the anaerobic fermentation residues and recycling the high-quality lignin.

The foregoing is illustrative of the preferred embodiments of this invention, and it is to be understood that the invention is not limited to the precise form disclosed herein and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the concept as disclosed herein, either as described above or as apparent to those skilled in the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. The method for processing the edible fungus dregs is characterized by comprising the following steps:

2. The process of claim 1, wherein in S3, the extractant used in the reflux extraction is a mixture of at least one of the ethanol, the isopropanol, the formic acid, the acetic acid and the gamma valerolactone and the water.

3. The process of claim 2, wherein in S3, the extractant used in the reflux extraction is at least one of the ethanol and the isopropanol, at least one of the formic acid and the acetic acid, and the water, or a mixture of the at least one of the formic acid and the acetic acid and the water, or a mixture of the gamma valerolactone and the water.

4. The treatment method according to claim 1, wherein in S3, before the reflux extraction, the method further comprises the steps of drying, grinding and screening the water washing residue in sequence to obtain an extract to be extracted;

and/or in S3, the temperature of the reflux extraction is 90-110 ℃, and the time of the reflux extraction is 24 h.

5. The process according to claim 4, wherein in S3, the weight-to-volume ratio of the extract to the extractant is 1:20(g: mL);

and/or in S3, the drying temperature is 80 ℃, and the drying time is 48 h;

and/or, in S3, the sieving is through an 80 mesh sieve.

6. The process of claim 1, wherein in S1, the anaerobic digestion is carried out by mixing the edible fungus dregs, the livestock manure and the inoculum sufficiently to obtain a mixture, and fermenting the mixture under anaerobic condition until no gas is produced.

7. The treatment method of claim 6, wherein the livestock manure comprises at least one of chicken manure, cattle manure, and pig manure;

and/or the inoculum is anaerobic fermentation digested sludge;

and/or the mass ratio of volatile solids in the edible fungus residues to volatile solids in the livestock and poultry manure is (1-2) to (1-2);

and/or the mass of the volatile solid in the inoculum accounts for 30% of the total mass of the volatile solid in the edible fungus residues and the volatile solid in the livestock manure;

and/or the solid content of the mixture is 10-15 wt%;

and/or the fermentation is medium-temperature fermentation or high-temperature fermentation; wherein the fermentation temperature of the medium-temperature fermentation is 30-40 ℃, and the fermentation temperature of the high-temperature fermentation is 50-60 ℃;

and/or the pH value of the fermentation is 6.8-7.2.

8. The treatment method according to claim 1, wherein in S2, the water washing comprises the steps of washing, centrifugation and solid-liquid separation in this order;

and/or, in S2, the number of times of water washing is at least three.

9. The process according to claim 1, wherein, in S5, before the extraction liquid is sequentially subjected to concentration, precipitation, centrifugation and solid-liquid separation, the process further comprises the steps of washing the extraction residue with the extractant to obtain a washing liquid, and mixing the washing liquid with the extraction liquid;

and/or, in S5, the precipitation is to mix the concentrated solution obtained by the concentration with deionized water to precipitate lignin.

10. Use of a treatment according to any one of claims 1 to 9 for the production of biogas and/or the extraction of lignin.