阅读说明：本技术 一种利用瘤胃微生物提高餐厨垃圾糖化渣发酵产酸的方法 (Method for improving acid production of kitchen waste saccharified residue through fermentation by using rumen microorganisms ) 是由 马鸿志 靳勇 林雨佳 高明 汪群慧 于 2019-11-14 设计创作，主要内容包括：本发明提供一种利用瘤胃微生物提高餐厨垃圾糖化渣发酵产酸的方法,属于固废资源化利用技术领域。该方法首先收集餐厨垃圾,去除浮油后搅碎,按体积比2:1加水,加入糖化酶糖化6小时后离心制备餐厨垃圾糖化渣；然后将餐厨垃圾糖化渣接入驯化的接种污泥,厌氧发酵产酸3～5天得发酵混合液1；再将发酵混合液1接入驯化的瘤胃液,厌氧发酵10～14天,收集发酵混合液2,即为目标发酵液。该方法利用瘤胃微生物中的乳酸分解菌分解糖化渣发酵所产乳酸,后经丙烯酸和琥珀酸途径转化成丙酸,以期获得更多的短链脂肪酸。该方法与接种驯化污泥生产VFAs相比,产率提高了37.49％。该方法不仅可以优化生产短链脂肪酸,同时也实现了餐厨垃圾的资源化利用。(The invention provides a method for improving acid production by fermentation of food waste saccharification residues by using rumen microorganisms, and belongs to the technical field of solid waste resource utilization. Firstly, collecting kitchen waste, removing floating oil, stirring, adding water according to the volume ratio of 2:1, adding saccharifying enzyme for saccharification for 6 hours, and centrifuging to prepare food waste saccharified slag; then inoculating the food waste saccharified residue into domesticated inoculated sludge, and performing anaerobic fermentation to produce acid for 3-5 days to obtain a fermentation mixed solution 1; and then inoculating the fermentation mixed solution 1 into the domesticated rumen fluid, performing anaerobic fermentation for 10-14 days, and collecting the fermentation mixed solution 2 to obtain the target fermentation solution. The method utilizes lactic acid decomposing bacteria in rumen microorganisms to decompose and ferment saccharified residue to produce lactic acid, and then the lactic acid is converted into propionic acid through acrylic acid and succinic acid ways so as to obtain more short-chain fatty acids. Compared with the method for producing VFAs by inoculating and domesticating sludge, the yield of the method is improved by 37.49%. The method can optimize the production of short-chain fatty acid and realize the resource utilization of the kitchen waste.)

1. A method for improving acid production of kitchen waste saccharified residue fermentation by using rumen microorganisms is characterized by comprising the following steps: the method comprises the following steps:

(1) collecting the kitchen waste, removing floating oil, stirring the kitchen waste by using a stirrer, adding water into the stirred kitchen waste according to the volume ratio of 2: 1-1: 1, adding saccharifying enzyme, saccharifying for 6-8 h, and centrifuging to prepare the food waste saccharified slag;

(2) placing the food waste saccharification residues obtained in the step (1) into a reactor, adding water to adjust the TS content to 10%, and then adjusting the pH value to 7;

(3) placing the kitchen waste saccharified residue treated in the step (2) in an anaerobic fermentation tank, inoculating domesticated sludge for fermentation treatment, and collecting a fermentation mixed solution 1 after 3-5 days;

(4) and (3) inoculating the obtained fermentation mixed solution 1 into domesticated rumen fluid, performing anaerobic fermentation for 10-14 days, and collecting the fermentation mixed solution 2 to obtain the target fermentation solution.

2. The method for improving acid production by fermentation of food waste saccharified residue by using rumen microorganisms as claimed in claim 1, wherein: the kitchen garbage in the step (1) contains one or more of starch, sugar, cellulose, protein and fat.

3. The method for improving acid production by fermentation of food waste saccharified residue by using rumen microorganisms as claimed in claim 1, wherein: and (2) adding saccharifying enzyme in the step (1), wherein the enzyme activity of saccharifying liquid is 50-100U/g according to the enzyme activity/fermentation liquid mass.

4. The method for improving acid production by fermentation of food waste saccharified residue by using rumen microorganisms as claimed in claim 1, wherein: the saccharification temperature in the step (1) is 55-60 ℃.

5. The method for improving acid production by fermentation of food waste saccharified residue by using rumen microorganisms as claimed in claim 1, wherein: the centrifugal rotating speed in the step (1) is 200-220 r/min.

6. The method for improving acid production by fermentation of food waste saccharified residue by using rumen microorganisms as claimed in claim 1, wherein: the domesticated sludge in the step (3) is obtained after anaerobic domestication of excess sludge of a sewage treatment plant for 10-15 days, wherein TS of saccharified slag is 26-30%, VS is 25-30%, TS of domesticated sludge is 8-10%, and VS is 5-7%; the sum of the sludge inoculation amount and VS of the saccharification slag accounts for 8-12% of VS of the total fermentation liquid.

7. The method for improving acid production by fermentation of food waste saccharified residue by using rumen microorganisms as claimed in claim 6, wherein: the domestication method of the domesticated sludge comprises the following steps: standing the residual sludge of the sewage treatment plant at normal temperature for 24 hours, heating in a water bath at 105 ℃ for 2 hours, transferring to a serum bottle for culture, adding 10g/L of kitchen waste every day for anaerobic acclimation culture, and obtaining acclimated sludge when the pH value is reduced to 6.0-6.5.

8. The method for improving acid production by fermentation of food waste saccharified residue by using rumen microorganisms as claimed in claim 1, wherein: the fermentation temperature in the step (3) and the fermentation temperature in the step (4) are both 30-37 ℃.

9. The method for improving acid production by fermentation of food waste saccharified residue by using rumen microorganisms as claimed in claim 1, wherein: the rumen fluid domesticated in the step (4) is rumen fluid of 3-5 hours after a ruminant eats in a farm, the VS of the domesticated rumen fluid is 5-7%, and the inoculation amount of the rumen fluid ensures that the sum of the VS of the rumen fluid and the saccharified residue accounts for 8-12% of the VS of the total fermentation liquid.

10. The method for improving acid production by fermentation of food waste saccharified residue by using ruminal microorganisms as claimed in claim 9, wherein: the domestication method of the domesticated rumen fluid comprises the following steps: taking rumen fluid from a ruminant body, quickly transferring the rumen fluid into a fermentation tank, adding a mineral buffer solution with the volume of 10-15% of the rumen fluid, regularly adding 10g/L of kitchen waste every day, maintaining the pH value in the fermentation tank to be 6.0-6.4 by adjusting the concentration of NaOH in the buffer solution, controlling the temperature to be 37 ℃, and controlling the stirring speed to be 100 r/min; detecting the composition of components in the generated gas every day, and completing the acclimation of rumen fluid when only hydrogen and carbon dioxide are contained in the gas components and methane cannot be detected in two consecutive days.

Technical Field

The invention relates to the technical field of solid waste resource utilization, in particular to a method for improving acid production of kitchen waste saccharified residue through fermentation by using rumen microorganisms.

Background

Kitchen waste is an organic solid waste mainly originating from enterprises and public institutions, catering industry, farmer markets, dining halls and households. The kitchen waste has the characteristics of high moisture, high organic matter content, easiness in generation of odor, easiness in biodegradation and the like, and resources and other wastes and environmental pollution can be caused if the kitchen waste is not properly treated. The main treatment modes of the kitchen waste in China are landfill and incineration, but the two treatment methods can cause a series of environmental pollution problems and waste the biomass resources of the kitchen waste. In addition, such as consumption by the sea, as animal feed and fertilizer, etc., are also prohibited due to increasingly stringent environmental laws and regulations. Therefore, the method has important practical significance for effectively recycling the kitchen waste in the current society with extremely short energy sources.

The kitchen waste is treated by anaerobic fermentation, so that secondary pollution of the kitchen waste to the environment can be reduced, and resources can be recovered, and the kitchen waste is widely concerned by researchers at home and abroad at present. However, most researchers concentrate on generating hydrogen and methane through anaerobic fermentation, but the yield of hydrogen and methane is not high and the transportation is not easy, so that the economic benefit of kitchen waste recycling is not optimistic. Anaerobic microorganisms are utilized to convert organic matters in the kitchen waste into volatile fatty acids, including acetic acid, propionic acid, isobutyric acid, butyric acid, isovaleric acid, valeric acid and the like, and the short-chain fatty acids have wide application, such as endogenous carbon serving as denitrifying and dephosphorizing bacteria in a sewage treatment plant, production raw materials of butyric acid and propionic acid which are extracted and separated and used in the fermentation industry are utilized by microorganisms to produce biodegradable plastics, and the volatile fatty acids are used as the raw materials to produce biogas, biodiesel, electricity generation, synthetic surfactants and the like.

After the food waste is saccharified, macromolecular substances such as saccharides and proteins are further converted into micromolecular substances, and the mass transfer effect of anaerobic fermentation is facilitated. After saccharification and centrifugation, the saccharification liquid contains a large amount of carbohydrate substances in the kitchen waste, and the saccharification residues of the kitchen waste are solid waste obtained after the kitchen waste is saccharified and centrifuged, and the main components of the saccharification residues comprise organic substances such as protein, starch, part of soluble sugar and the like. The saccharified residue is subjected to anaerobic fermentation to generate volatile fatty acid and a large amount of lactic acid.

Rumen microorganisms of ruminant livestock can generally convert carbohydrates such as fiber, starch, soluble sugar and the like in feed into pyruvic acid through digestion and metabolism, enter tricarboxylic acid cycle and respectively generate volatile fatty acids such as acetic acid, propionic acid, butyric acid and the like through different metabolic pathways. Megacoccus aegypti (Megasphaera elsdenii) in the rumen is the most important lactic acid-decomposing bacterium, and in addition to glucose, maltose, and the like produced by fermentation using a substrate in competition with lactic acid-producing bacteria, lactic acid is preferably decomposed as a carbon source for self-proliferation of acid production. Elsdenii converts lactic acid to propionic acid mainly through both the acrylic and succinic pathways, and also produces small amounts of acetic acid through the acetyl-coa pathway.

Researches on optimizing short-chain fatty acid produced by kitchen waste are quite extensive, but at present, researches on converting lactic acid produced by kitchen waste fermentation into short-chain fatty acid are not available, and researches on producing short-chain fatty acid by anaerobic fermentation of saccharification residues of kitchen waste are not available.

Disclosure of Invention

The invention provides a method for improving acid production of kitchen waste saccharified residue through fermentation by using rumen microorganisms, aiming at solving the problem of low yield of short-chain fatty acid in the existing acid production method by using kitchen waste through anaerobic fermentation.

The method comprises the following steps:

(1) collecting the kitchen waste, removing floating oil, stirring the kitchen waste by using a stirrer, adding water into the stirred kitchen waste according to the volume ratio of 2: 1-1: 1, adding saccharifying enzyme, saccharifying for 6-8 h, and centrifuging to prepare the food waste saccharified slag;

(2) placing the food waste saccharification slag obtained in the step (1) into a reactor, adding water to adjust TS (Total Solid content) to 10%, and then adjusting the pH value to 7;

(3) placing the kitchen waste saccharified residue treated in the step (2) in an anaerobic fermentation tank, inoculating domesticated sludge for fermentation treatment, and collecting a fermentation mixed solution 1 after 3-5 days;

(4) and (3) inoculating the obtained fermentation mixed solution 1 into domesticated rumen fluid, performing anaerobic fermentation for 10-14 days, and collecting the fermentation mixed solution 2 to obtain the target fermentation solution.

Wherein, the kitchen garbage in the step (1) mainly comprises substances such as starch, sugar, cellulose, protein, fat and the like.

And (2) adding saccharifying enzyme in the step (1) to enable the enzyme activity of the saccharifying liquid to be 50-100U/g (enzyme activity/fermentation liquid).

In the step (1), the saccharification temperature is 55-60 ℃.

The centrifugal rotating speed in the step (1) is 200-220 r/min.

The domesticated sludge in the step (3) is obtained after anaerobic domestication of excess sludge of a sewage treatment plant for 10-15 days, wherein TS (Total Solid content) of saccharified slag is 26-30%, VS (Volatile Solid content) is 25-30%, TS of the domesticated sludge is 8-10%, and VS is 5-7%. The sum of the sludge inoculation amount and VS of the saccharification slag accounts for 8-12% of VS of the total fermentation liquid.

The domestication method for domesticating the sludge comprises the following steps: standing the residual sludge of the sewage treatment plant for 24 hours at normal temperature, and heating in a water bath at 105 ℃ for 2 hours. And then transferring the mixture to a serum bottle for culture, adding 10g/L of kitchen waste every day at regular time (24h) for anaerobic acclimation culture, and obtaining acclimated sludge when the pH value is reduced to 6.0-6.5.

The fermentation temperature in the step (3) is 35-37 ℃.

And (4) the rumen fluid domesticated in the step (4) is rumen fluid after a ruminant eats for 3-5 h in a farm, the VS of the domesticated rumen fluid is 5-7%, and the inoculation amount of the rumen fluid ensures that the sum of the VS of the rumen fluid and the saccharified residue accounts for 8-12% of the VS of the total fermentation liquid.

The domestication method of the domesticated rumen fluid comprises the following steps: 300mL of rumen fluid is taken from a ruminant and quickly transferred to a 500mL fermentation tank, 37mL of mineral buffer solution (eufen buffer solution) is added, 10g/L of kitchen waste is added at regular time (24h) every day, the pH value in the fermentation tank is maintained to be 6.0-6.4 by adjusting the concentration of NaOH in the buffer solution, the temperature is 37 ℃, and the stirring speed is 100 r/min. Detecting the composition of components in the generated gas every day, and completing the rumen microbial acclimation when only hydrogen and carbon dioxide are contained in the gas components and methane is not detected in the gas components for two consecutive days.

The mineral buffer solution mainly comprises a peifene buffer solution, a meconium buffer solution and the like, wherein the composition of the peifene buffer solution is NaHCO₃5g/L，Na₂HPO₄1.9g/L，KCl 0.5g/L，MgCl₂·6H₂O 0.13g/L，CaCl₂0.05g/L and 0.5g/L of urea; the composition of the meconium buffer solution is Na₂CO₃3.1g/L，K₂CO₃4.0g/L，Na₂HPO₄0.9g/L，K₂HPO₄1.1g/L，MgCl₂·6H₂O 0.10g/L，CaCl₂0.04g/L and 0.5g/L of urea.

The fermentation temperature in the step (4) is 30-37 ℃.

The technical scheme of the invention has the following beneficial effects:

in the scheme, lactic acid produced by decomposing and fermenting saccharification residues by using lactic acid decomposing bacteria in rumen microorganisms is mainly utilized, and then the lactic acid is converted into propionic acid through an acrylic acid and succinic acid way so as to obtain more short-chain fatty acids. Compared with fermentation production without acclimatization treatment, the method of the invention has 37.49% higher efficiency than the method for producing VFAs by inoculating and acclimatizing sludge. The method of the invention not only can optimize the production of short-chain fatty acid, but also realizes the resource utilization of the kitchen waste.

Drawings

FIG. 1 is a technical scheme diagram of a method for improving acid production by fermentation of food waste saccharified residues by using rumen microorganisms according to the present invention;

FIG. 2 shows the concentration change of lactic acid produced by anaerobic fermentation of the food waste saccharified residue in the embodiment of the invention;

FIG. 3 shows the concentration change of VFAs produced by anaerobic fermentation of the food waste saccharified residue in the embodiment of the invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.

The invention provides a method for improving acid production by fermenting food waste saccharified residue by using rumen microorganisms.

As shown in fig. 1, the method comprises the steps of:

(1) collecting the kitchen waste, removing floating oil, stirring the kitchen waste by using a stirrer, adding water into the stirred kitchen waste according to the volume ratio of 2: 1-1: 1, adding saccharifying enzyme, saccharifying for 6-8 h, and centrifuging to prepare the food waste saccharified slag;

(2) placing the food waste saccharification slag obtained in the step (1) into a reactor, adding water to adjust the content of TS (Total Solid) to 10%, and then adjusting the pH value to 7;

(3) placing the kitchen waste saccharified residue treated in the step (2) in an anaerobic fermentation tank, inoculating domesticated sludge for fermentation treatment, and collecting a fermentation mixed solution 1 after 3-5 days;

(4) and (3) inoculating the obtained fermentation mixed solution 1 into domesticated rumen fluid, performing anaerobic fermentation for 10-14 days, and collecting the fermentation mixed solution 2 to obtain the target fermentation solution.

The following description is given with reference to specific examples.