CN111394402A - Method for co-producing medium-chain fatty acid and biogas by using wood fiber raw material - Google Patents
Method for co-producing medium-chain fatty acid and biogas by using wood fiber raw material Download PDFInfo
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- CN111394402A CN111394402A CN202010156949.6A CN202010156949A CN111394402A CN 111394402 A CN111394402 A CN 111394402A CN 202010156949 A CN202010156949 A CN 202010156949A CN 111394402 A CN111394402 A CN 111394402A
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
- C12P7/00—Preparation of oxygen-containing organic compounds
- C12P7/64—Fats; Fatty oils; Ester-type waxes; Higher fatty acids, i.e. having at least seven carbon atoms in an unbroken chain bound to a carboxyl group; Oxidised oils or fats
- C12P7/6409—Fatty acids
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
- C12P5/00—Preparation of hydrocarbons or halogenated hydrocarbons
- C12P5/02—Preparation of hydrocarbons or halogenated hydrocarbons acyclic
- C12P5/023—Methane
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
- C12P2201/00—Pretreatment of cellulosic or lignocellulosic material for subsequent enzymatic treatment or hydrolysis
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
- C12P2203/00—Fermentation products obtained from optionally pretreated or hydrolyzed cellulosic or lignocellulosic material as the carbon source
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E50/00—Technologies for the production of fuel of non-fossil origin
- Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel
Abstract
The invention provides a method for co-producing medium-chain fatty acid and biogas by using wood fiber raw materials. A method for coproducing medium-chain fatty acid and biogas from wood fiber raw materials comprises the following steps: (1) mixing the crushed wood fiber raw material with an alkaline solution for pretreatment, and performing solid-liquid separation on the pretreated mixture to respectively obtain a hydrolysate and solid residues; (2) mixing the hydrolysate with anaerobic digestion sludge, adjusting the pH to 5.0-5.5, continuing anaerobic fermentation, and adding ethanol or lactic acid in the fermentation process to respectively obtain medium-chain fatty acid and extracted fermentation liquor; (3) and (3) mixing the solid residue obtained in the step (1) with the extracted fermentation liquor obtained in the step (2), and continuously performing anaerobic fermentation for 20-50 days to obtain the biogas. The invention aims at the characteristics of alkaline pretreatment and anaerobic fermentation of wood fiber raw materials, establishes a method for co-producing biogas and medium-chain fatty acid, and realizes the gradient utilization of the wood fiber raw materials.
Description
The technical field is as follows:
the invention relates to the technical field of waste recycling, in particular to a method for co-producing medium-chain fatty acid and biogas by using wood fiber raw materials.
Background art:
the wood fiber raw materials such as straw, energy herbaceous plants and the like are the most abundant and sustainable carbon-hydrogen biomass resources on the earth, and have the characteristics of wide sources, high yield, stable components and the like. With the continuous development of biomass energy, the conversion of wood fiber raw materials such as straws, energy plants and the like to prepare energy or bio-based products is receiving more and more attention, and the method plays an important role in prolonging the modern agricultural industry chain, driving the industrial industry to upgrade, promoting the economic development of rural towns, relieving the ecological environment pressure and improving the energy structure.
The main components of the wood fiber raw material are cellulose, hemicellulose and lignin, wherein the cellulose and the hemicellulose account for about 66-75 percent and are the main available components. However, due to the close crosslinking of the cellulose in the lignocellulosic raw material, the hydrolysis of the lignocellulosic raw material is hindered by the special structure, the protective effect of lignin, the crystallization of cellulose and the like, and the utilization efficiency is affected. Thus, there is a need for pretreatment of lignocellulosic feedstocks to increase the efficiency of hydrolysis of the feedstock and thus increase conversion. The alkaline treatment is proved to be very suitable for being used as a pretreatment process of anaerobic fermentation of the wood fiber raw material, most of hydrolysis liquid after pretreatment is hemicellulose hydrolysis product, while solid residue is mainly cellulose, and the solid residue has different product component characteristics and has the potential of grading utilization.
Anaerobic fermentation technology is one of the most potential lignocellulose biomass resource utilization technologies. At present, the technology for preparing the biogas by anaerobic fermentation of the wood fiber raw material is rapidly developed in China, the construction of related bioenergy engineering is accelerated, and the problems of long fermentation period, low conversion efficiency, insufficient expression of product value and the like still exist. In recent years, in addition to the preparation of biogas by using anaerobic technology, a new idea of preparing Volatile Fatty Acids (VFAs) by anaerobic fermentation is proposed in the field of international anaerobic technology aiming at anaerobic digestion characteristics and self-limitations, and the method is a promising high-valued utilization approach. The medium-chain carboxylic acid such as caproic acid is one of the most potential platform compounds due to the characteristics of high energy density, strong hydrophobicity, high added value and relative easiness in subsequent separation and purification.
The invention content is as follows:
the invention aims to provide a method for co-producing medium-chain fatty acid and biogas from a wood fiber raw material, and the method is established for co-producing biogas and medium-chain fatty acid aiming at the characteristics of alkaline pretreatment and anaerobic fermentation of the wood fiber raw material, so as to realize gradient utilization of the wood fiber raw material.
The invention aims to provide a method for coproducing medium-chain fatty acid and biogas from a wood fiber raw material, which comprises the following steps:
(1) mixing the crushed wood fiber raw material with an alkaline solution in a solid-to-liquid ratio of 1: 10-1: 40, setting the temperature to be 30-80 ℃, carrying out pretreatment for 12-48 hours, carrying out solid-liquid separation on the pretreated mixture to obtain a hydrolysate and solid residues respectively, wherein the hydrolysate is rich in organic matters such as xylan, xylose, glycolic acid and acetic acid;
(2) mixing the hydrolysate obtained in the step (1) with anaerobic digestion sludge, adjusting the pH to 5.0-5.5, continuing to perform anaerobic fermentation for 15-30 days at the fermentation temperature of 25-35 ℃, adding ethanol or lactic acid in the fermentation process to obtain fermentation liquor containing medium-chain fatty acids, and extracting the medium-chain fatty acids to respectively obtain the medium-chain fatty acids and the fermentation liquor after extraction;
(3) and (3) mixing the solid residue obtained in the step (1) with the extracted fermentation liquor obtained in the step (2), and continuously performing anaerobic fermentation for 20-50 days to obtain the biogas.
Preferably, the mass fraction of the alkaline substance in the alkaline solution in the step (1) is 2% -8%, and the alkaline substance is selected from one or more of sodium hydroxide, calcium hydroxide, potassium hydroxide and ammonia water.
Preferably, the anaerobic digested sludge in the step (2) can be from fermentation liquor obtained by anaerobic fermentation engineering in normal operation, and can also be from fermentation liquor after gas production in the step (3) through anaerobic fermentation.
Preferably, the addition amount of the ethanol or the lactic acid in the step (2) is 1.5-3 g of ethanol or lactic acid added to 100g of fermentation broth, the addition interval time of the ethanol or the lactic acid is 8-20 days, and the addition times are 2-4 times.
Preferably, the medium-chain fatty acid in step (2) is hexanoic acid or octanoic acid.
Preferably, the solid-liquid ratio of the solid residue in the step (3) to the fermentation liquid after extraction is 0.03-0.15 g/m L.
Preferably, the wood fiber raw material is crop straw or energy grass.
Unless otherwise defined, the present invention is directed to the definitions of terms having the same meaning as commonly understood by one of ordinary skill in the art.
Compared with the prior art, the invention has the following advantages:
(1) the invention utilizes an alkali treatment method to roughly divide the wood fiber raw material into solid residue mainly containing cellulose and hydrolysate mainly containing hemicellulose hydrolysate, and respectively carries out biogas production and medium-chain fatty acid production aiming at different characteristics of the products, thereby realizing the graded utilization of the wood fiber raw material.
(2) The invention realizes the co-production of the biogas and the medium-chain fatty acid, and increases the product types and the added value compared with the traditional anaerobic fermentation process; the fermentation liquor after acid extraction and the pretreated solid residue generate gas together in an anaerobic way, so that the effective components are recycled, and the conversion efficiency of the raw materials is increased.
(3) The invention adopts a biological method to prepare the clean energy biogas and the carboxylic acid platform compounds such as caproic acid and the like, can realize the energy regeneration and the resource utilization of the organic wastes such as straws and the like, and is a green and clean process compared with the preparation of the products by utilizing petrochemical raw materials, and the energy and the high-added-value platform compounds are co-produced while the organic wastes such as straws and the like are treated.
Description of the drawings:
FIG. 1 is a schematic process flow diagram of a method for co-producing medium-chain fatty acids and biogas from a wood fiber raw material according to the present invention.
The specific implementation mode is as follows:
the following examples are further illustrative of the present invention and are not intended to be limiting thereof. Anaerobic digestion sludge is commercially available.
Example 1:
as shown in figure 1, the method for co-producing hexanoic acid and biogas by hybrid pennisetum comprises the following steps:
(1) crushing fresh hybrid pennisetum to be less than 1cm, adding sodium hydroxide solution according to the amount that sodium hydroxide solution with the mass fraction of 2 percent is added into the fresh hybrid pennisetum in an amount of 40m L/g, setting the temperature to be 30 ℃, reacting for 48 hours for pretreatment, and performing solid-liquid separation on the mixture after the pretreatment to respectively obtain pretreated hydrolysate and solid residues;
(2) mixing the pretreated hydrolysate obtained in the step (1) with anaerobic digested sludge, adjusting the pH to 5.5 by using hydrochloric acid or sulfuric acid, continuously maintaining anaerobic fermentation for 30 days, wherein the fermentation temperature is 25 ℃, adding ethanol at 1 st day, 8 th day, 16 th day and 24 th day of fermentation respectively, adding 1.5g of ethanol into each 100g of fermentation broth to obtain fermentation broth of the fermentation broth with the caproic acid concentration of 5 g/L and the caprylic acid concentration of 1 g/L, and extracting caproic acid in the fermentation broth by using an extraction method to obtain caproic acid and the extracted fermentation broth respectively;
(3) and (3) mixing the solid residue obtained in the step (1) with the mixture of the fermentation liquor obtained after extraction in the step (2), wherein the solid-liquid ratio of the solid residue to the fermentation liquor obtained after extraction is 0.15g/m L, and continuously performing anaerobic fermentation for 50 days to obtain the biogas with the methane content of 50-60%.
Example 2:
as shown in figure 1, the method for co-producing caproic acid and biogas by anaerobic fermentation of corn stalks comprises the following steps:
(1) crushing the corn stalks to be less than 2cm, adding 8 mass percent of potassium hydroxide solution according to the amount of 10m L/g of fresh hybrid pennisetum alopecuroides, setting the temperature to be 80 ℃, reacting for 12 hours for pretreatment, and performing solid-liquid separation on the mixture after the pretreatment to respectively obtain pretreated hydrolysate and solid residues;
(2) mixing the pretreated hydrolysate obtained in the step (1) with anaerobic digested sludge, adjusting the pH to 5.0 by using hydrochloric acid or sulfuric acid, continuing to perform anaerobic fermentation for 15 days, wherein the fermentation temperature is 35 ℃, adding 3g of ethanol into every 100g of fermentation broth on the 1 st day and the 10 th day of fermentation respectively, so as to obtain the concentration of caproic acid of 6 g/L, and extracting caproic acid and caprylic acid in the solution by using an extraction method, so as to obtain caproic acid, caprylic acid and the extracted fermentation broth respectively;
(3) and (3) mixing the solid residue obtained in the step (1) with the mixture of the fermentation liquor obtained after extraction in the step (2), wherein the solid-liquid ratio of the solid residue to the fermentation liquor obtained after extraction is 0.03g/m L, and continuously performing anaerobic fermentation for 20 days to obtain the biogas with the methane content of 50-60%.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, simplifications, etc., which are made without departing from the spirit and principle of the present invention, should be regarded as being equivalent to the replacement of the above embodiments, and are included in the scope of the present invention.
Claims (7)
1. A method for coproducing medium-chain fatty acid and biogas from wood fiber raw materials is characterized by comprising the following steps:
(1) mixing the crushed wood fiber raw material with an alkaline solution in a solid-to-liquid ratio of 1: 10-1: 40, setting the temperature to be 30-80 ℃, carrying out pretreatment for 12-48 hours, and carrying out solid-liquid separation on the pretreated mixture to obtain a hydrolysate and solid residues respectively;
(2) mixing the hydrolysate obtained in the step (1) with anaerobic digestion sludge, adjusting the pH to 5.0-5.5, continuing to perform anaerobic fermentation for 15-30 days at the fermentation temperature of 25-35 ℃, adding ethanol or lactic acid in the fermentation process to obtain fermentation liquor containing medium-chain fatty acids, and extracting the medium-chain fatty acids to respectively obtain the medium-chain fatty acids and the fermentation liquor after extraction;
(3) and (3) mixing the solid residue obtained in the step (1) with the extracted fermentation liquor obtained in the step (2), and continuously performing anaerobic fermentation for 20-50 days to obtain the biogas.
2. The method for coproducing medium-chain fatty acid and biogas from lignocellulosic raw materials as claimed in claim 1, wherein the alkaline solution in the step (1) contains 2-8% by mass of alkaline substances, and the alkaline substances are selected from one or more of sodium hydroxide, calcium hydroxide, potassium hydroxide and ammonia water.
3. The method for coproducing medium-chain fatty acid and biogas from a wood fiber raw material as recited in claim 1, wherein the ethanol or lactic acid is added in an amount of 1.5-3 g per 100g of fermentation broth in step (2), the time interval between the addition of ethanol or lactic acid is 8-20 days, and the number of addition is 2-4.
4. The method for co-producing medium-chain fatty acid and biogas from a lignocellulosic feedstock as claimed in claim 1, wherein the anaerobically digested sludge in step (2) is a fermentation broth obtained from a normally operated anaerobic fermentation process or a fermentation broth after the gas is produced from the anaerobic fermentation in step (3).
5. The method for co-producing medium-chain fatty acid and biogas as defined in claim 1 or 2, wherein the medium-chain fatty acid in step (2) is hexanoic acid or octanoic acid.
6. The method for co-producing medium-chain fatty acid and biogas from lignocellulosic raw material according to claim 1 or 2, wherein the solid-to-liquid ratio of the solid residue to the fermentation broth after extraction in step (3) is 0.03-0.15 g/m L.
7. The method for co-producing medium-chain fatty acids and biogas from lignocellulosic feedstocks according to claim 1 or 2, wherein the biomass is crop straw or energy grass.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113214497A (en) * | 2021-05-06 | 2021-08-06 | 西华大学 | Method for recovering lignin from enzymolysis residues of lignocellulose |
| CN114317618A (en) * | 2022-01-05 | 2022-04-12 | 中国科学院广州能源研究所 | Lignocellulose raw material gradient utilization process based on alkali pretreatment |
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| CN104328144A (en) * | 2014-09-30 | 2015-02-04 | 中国热带农业科学院海口实验站 | Method for producing hexanoic acid and octanoic acid through fermentation of lignocellulose by undefined mixed microflora |
| CN106929547A (en) * | 2016-12-29 | 2017-07-07 | 湖南大学 | A kind of method of the efficient co-production of methane of utilization straw and ethanol |
| US20200017891A1 (en) * | 2018-07-11 | 2020-01-16 | Wisconsin Alumni Research Foundation | Microbiomes and methods for producing medium-chain fatty acids from organic substrates |
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2020
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104328144A (en) * | 2014-09-30 | 2015-02-04 | 中国热带农业科学院海口实验站 | Method for producing hexanoic acid and octanoic acid through fermentation of lignocellulose by undefined mixed microflora |
| CN106929547A (en) * | 2016-12-29 | 2017-07-07 | 湖南大学 | A kind of method of the efficient co-production of methane of utilization straw and ethanol |
| US20200017891A1 (en) * | 2018-07-11 | 2020-01-16 | Wisconsin Alumni Research Foundation | Microbiomes and methods for producing medium-chain fatty acids from organic substrates |
Non-Patent Citations (3)
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113214497A (en) * | 2021-05-06 | 2021-08-06 | 西华大学 | Method for recovering lignin from enzymolysis residues of lignocellulose |
| CN114317618A (en) * | 2022-01-05 | 2022-04-12 | 中国科学院广州能源研究所 | Lignocellulose raw material gradient utilization process based on alkali pretreatment |
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