阅读说明：本技术 一种促进草类生物质厌氧发酵生产挥发性脂肪酸的方法 (Method for promoting anaerobic fermentation of grass biomass to produce volatile fatty acid ) 是由 陶雪 熊小燕 于 2020-05-27 设计创作，主要内容包括：本发明公开了一种促进草类生物质厌氧发酵生产挥发性脂肪酸的方法,该方法是将经电石渣预处理后的草类生物质作为厌氧发酵底物,再按一定的比例接种种泥,在严格厌氧的反应器中发酵生产挥发性脂肪酸,发酵结束后测定发酵液中挥发性脂肪酸的产量。本发明采用经电石渣预处理后的草类生物质发酵生产挥发性脂肪酸,在高效促进挥发性脂肪酸生产的同时,提高了草类生物质这类废弃物的无害化和资源化利用,操作运行简单,产物效率高,降低发酵成本,具有很好的应用价值和应用前景,为实现固废资源化利用提供一种新方法,同时拓宽了电石渣的应用范围,具有重要的实际应用价值。(The invention discloses a method for promoting anaerobic fermentation of grass biomass to produce volatile fatty acid, which comprises the steps of taking the grass biomass pretreated by carbide slag as an anaerobic fermentation substrate, inoculating seed sludge according to a certain proportion, fermenting in a strict anaerobic reactor to produce the volatile fatty acid, and measuring the yield of the volatile fatty acid in fermentation liquor after the fermentation is finished. According to the invention, the grass biomass pretreated by the carbide slag is adopted to ferment and produce the volatile fatty acid, so that the harmless and resource utilization of the waste such as the grass biomass is improved while the production of the volatile fatty acid is efficiently promoted, the operation and operation are simple, the product efficiency is high, the fermentation cost is reduced, the application value and the application prospect are good, a new method is provided for realizing the resource utilization of solid waste, the application range of the carbide slag is widened, and the important practical application value is realized.)

1. A method for promoting anaerobic fermentation of grass biomass to produce volatile fatty acid is characterized by comprising the following steps: taking grass biomass pretreated by carbide slag as an anaerobic fermentation substrate, inoculating sludge, fermenting in a strictly anaerobic reactor to produce volatile fatty acid, and measuring the yield of the volatile fatty acid in fermentation liquor after fermentation is finished.

2. The method for promoting anaerobic fermentation of grass biomass to produce volatile fatty acids as claimed in claim 1, wherein: the pretreatment concentration of the carbide slag is 1.75%, w/v, the ratio of the grass biomass to the carbide slag solution is 1:2, g: ml, the pretreatment temperature is 120 ℃, and the pretreatment time is 40 min.

3. The method for promoting anaerobic fermentation of grass biomass to produce volatile fatty acids as claimed in claim 1, wherein: the grass biomass comprises switchgrass, alfalfa, triarrhena sacchariflora and lawn trimmings, and the particle size of the grass biomass is less than 3 cm.

4. The method for promoting anaerobic fermentation of grass biomass to produce volatile fatty acids as claimed in claim 2, wherein: the anaerobic fermentation substrate is obtained by washing a pretreatment mixed solution to be neutral after pretreatment of grass biomass and drying the washed solid to be constant weight at 65 ℃.

5. The method for promoting anaerobic fermentation of grass biomass to produce volatile fatty acids as claimed in claim 1, wherein: the inoculated sludge is granular sludge which contains microorganisms including proteus, bacteroides and sclerenchyma bacteria.

6. The method for promoting anaerobic fermentation of grass biomass to produce volatile fatty acids as claimed in claim 1, wherein: the anaerobic fermentation conditions of the grass biomass are as follows: adopting sequencing batch fermentation, mixing a fermentation substrate and inoculated sludge according to the ratio of 1:1 in VS calculation, adding distilled water into a 250ml serum bottle until the volume is 200ml, placing the serum bottle in a gas bath constant temperature oscillator, keeping the anaerobic environment at the fermentation temperature of 35 ℃, the rotation speed of 100r/min, charging nitrogen for 10min, then carrying out fermentation to produce volatile fatty acid, and continuing the fermentation for 14 d.

7. The method for promoting anaerobic fermentation of grass biomass to produce volatile fatty acids as claimed in claim 1, wherein: the determination step of the volatile fatty acid comprises the following steps: centrifuging the fermentation broth at 10000r/min and 4 deg.C for 10min at high speed by high speed centrifuge to obtain supernatant as volatile fatty acid-containing fermentation broth, and determining volatile fatty acid concentration and component ratio by Shimadzu gas chromatograph.

Technical Field

The invention relates to a method for promoting anaerobic fermentation of grass biomass to produce volatile fatty acid, and belongs to the technical field of solid waste recycling.

Background

The grassland area of China is about 4 hundred million hectares, and moreover, the grassland biomass can be planted in large-area marginal land of China, so that a large amount of grassland biomass can be generated every year. Compared with wood biomass, grass biomass has the characteristics of high growth speed, high yield, soft structure and the like. At present, except a small part of the grass biomass is utilized by livestock or used for producing energy, most of the grass biomass is abandoned or idled, so that the great waste of renewable resources is caused. The grass biomass mainly contains cellulose, hemicellulose, protein, lignin and other compounds, and can be reused by fermentation under the action of microorganisms to produce high value-added chemical products, such as hydrogen, volatile fatty acid, methane or ethanol. The value of producing the volatile fatty acid by anaerobic fermentation is more advantageous, the added value of the volatile fatty acid is high, the volatile fatty acid has a plurality of purposes, the volatile fatty acid can be used as an exogenous carbon source for promoting sewage treatment capability of a sewage treatment plant, various chemical compounds or energy substances can be further synthesized, and more importantly, the fermentation for producing the volatile fatty acid by anaerobic fermentation is easy to control, simple to operate, low in cost, short in period and high in efficiency.

Regarding the technology of producing volatile fatty acid by anaerobic fermentation, in the prior patent literature, CN101314783 invented by chenjiangjian et al at the university of south of the Yangtze river discloses a method for producing volatile fatty acid by anaerobic fermentation after thermal-alkaline pretreatment of organic waste with high solid concentration, the scheme takes municipal sludge as a model substrate and adopts thermal-alkaline pretreatment, then anaerobic acidification sludge after thermal stress treatment and acclimatization is inoculated as seed sludge for anaerobic fermentation, the solid mass concentration of the treated municipal sludge can be 3.7-12.0%, the highest yield of the volatile fatty acid can reach 0.23g of volatile fatty acid/g of organic matter, and the acid production is improved by 20.1-61.0% compared with the acid production by fermentation of sludge without pretreatment.

In addition, CN103194494B invented by king aijie et al of the university of harbin industry discloses a method for producing volatile fatty acid by co-fermentation of agaricus bisporus fungus chaff and excess sludge, so as to solve the problems of low acidification efficiency of the independent anaerobic fermentation of the excess sludge and disposal and utilization of the agaricus bisporus fungus chaff at present. The method comprises the following steps: firstly, preparing a sludge sample; secondly, preparing a mushroom bran sample; thirdly, adding a fungus bran sample; and fourthly, completing the method for producing the volatile fatty acid by co-fermenting the agaricus bisporus fungus chaff and the excess sludge. According to the method, the agaricus bisporus fungus chaff is used as an external carbon source to condition the excess sludge, and the yield of volatile acid in the excess sludge fermentation process is obviously improved by improving the carbon-nitrogen ratio of an excess sludge system.

CN110452936A, a method for improving the yield of volatile fatty acid by controlling anaerobic fermentation of kitchen waste water under negative pressure, is proposed by Huangjialong et al of the university of agriculture in Huazhong, and the method is used for extruding and filtering the kitchen waste of families or restaurants to obtain the kitchen waste water; collecting the collected matter, removing pollutants in the collected matter, and then fermenting for 6-8 days under the anaerobic environment condition; placing the pretreated sludge in a high-pressure steam sterilization pot for high-temperature sterilization, and cooling to 30 ℃; adding culture medium, and heating and culturing in water bath at 37 deg.C; obtaining anaerobic sludge, placing the anaerobic sludge and the kitchen wastewater in a fermentation tank, and using N₂After the air in the fermentation tank is discharged to create an anaerobic environment, the atmospheric pressure in the fermentation tank is reduced to 0.02 +/-0.005 MPa by using a negative pressure control device, and the fermentation tank is placed in a water bath for anaerobic fermentation; obtaining a supernatant; namely the volatile fatty acid. The method can increase the yield of volatile fatty acid by 20-50%, and increase the proportion of acetic acid, propionic acid and butyric acid in the volatile fatty acid by 4-10%.

However, the following aspects are not considered in the above prior arts: the method can effectively utilize grass biomass as resources through anaerobic fermentation, and has important significance for relieving the current fuel and environmental crisis. Although hemicellulose, cellulose and protein in the grass biomass are easily decomposed by anaerobic microorganisms, lignin is firm in structure and difficult to utilize, and the outer layer surrounding the cellulose is used as a protective layer, so that the degradation of the cellulose, the hemicellulose and the protein is hindered, the fermentation efficiency is reduced, and the yield of volatile fatty acid is further reduced. In order to increase the utilization rate of grass biomass, an efficient pretreatment method is therefore required to promote the degradation of grass biomass.

The alkaline pretreatment has good effect, and can break the structure of grass biomass so that the effective components of the biomass are beneficial to the utilization of microorganisms. In the traditional alkali treatment, high-cost sodium carbonate such as sodium hydroxide, calcium hydroxide and the like is mainly adopted, and the addition of the sodium carbonate increases the cost of sludge treatment during large-scale anaerobic sludge fermentation. Therefore, it is of great significance to find an alkaline substance to replace the traditional soda ash to treat grass biomass to promote fermentation and produce volatile fatty acid.

Carbide Slag (CS) is strong alkaline industrial waste slag, the main component of which is calcium oxide, and calcium hydroxide is formed by dissolving calcium oxide in water. The carbide slag pretreatment is a good choice for replacing the traditional alkali pretreatment, the alkali cost of the alkali pretreatment can be reduced, the waste is treated by the waste, and meanwhile, a high-value-added chemical product is produced, which is the thinking and development direction of the treatment and the treatment of the biomass solid waste at present and in the future, so that a certain theoretical basis is provided for the research on a new technology for the resource utilization of organic waste, and more importantly, the application range of the alkaline industrial waste residue such as the carbide slag is widened.

Disclosure of Invention

The invention aims to provide a method for promoting anaerobic fermentation of grass biomass to produce volatile fatty acid.

The invention is realized by the following steps:

the technical scheme of the invention is that grass biomass pretreated by carbide slag is used as a fermentation substrate, inoculated sludge is added, and fermentation is carried out under strict anaerobic conditions to produce volatile fatty acid. Realizing the reclamation of the grass biomass and the carbide slag. The method can reduce the cost of acid production by anaerobic fermentation of grass biomass, and the produced volatile fatty acid has wide application prospect and realizes the purpose of treating wastes with processes of wastes against one another.

The invention provides a method for pretreating grass biomass by using carbide slag, and a method for producing volatile fatty acid by fermenting the pretreated grass biomass under an anaerobic condition, which comprises the following steps:

(1) the pretreatment concentration of the carbide slag is 1.75% (w/v), the ratio of the grass biomass to the carbide slag solution is 1:2 (g: ml), the pretreatment temperature is 120 ℃, and the pretreatment time is 40 min. Taking grass biomass pretreated by carbide slag as an anaerobic fermentation substrate, adding seed mud according to a certain proportion, fermenting in a strictly anaerobic reactor to produce volatile fatty acid, and measuring the concentration and component proportion of the volatile fatty acid in fermentation liquor after fermentation.

(2) The grass biomass comprises switchgrass, alfalfa, silvergrass and lawn clippings, and has a particle size of less than 3 cm.

(3) The fermentation substrate is: after pretreatment, washing the pretreatment mixed liquor to be neutral, and drying the washed solid to be constant weight at 65 ℃, thus obtaining the substrate for anaerobic fermentation.

(4) The inoculated sludge is granular sludge from Anhui Bida environmental protection science and technology limited and mainly contains microorganisms such as proteobacteria, bacteroides and sclerenchyma bacteria.

(5) The anaerobic fermentation conditions of the grass biomass are as follows: adopting sequencing batch fermentation, mixing a fermentation substrate and inoculated sludge according to a ratio of 1:1 (calculated by VS), performing fermentation in a 250ml serum bottle, adding distilled water to 200ml of scale mark, placing the serum bottle in a gas bath constant temperature oscillator, performing fermentation at 35 ℃, rotating speed of 100r/min, charging nitrogen for 10min to maintain an anaerobic environment, and performing fermentation to produce volatile fatty acid for 14 days.

(6) The volatile fatty acid determination step comprises the following steps: and (3) centrifuging the fermentation liquor at 10000r/min and 4 ℃ for 10min at high speed by using a high-speed centrifuge, wherein the supernatant is the fermentation liquor containing VFAs, and then measuring the content of the volatile fatty acid by using an Shimadzu gas chromatograph.

(7) VFAs in all serum bottles mainly comprise acetic acid and propionic acid (accounting for more than 49.41% of the total volatile fatty acid proportion), and the concentration of the VFAs produced by fermenting the grass biomass after the carbide slag is pretreated can reach 10203.87mg/L, and is improved by 8.4 times compared with that of the original grass.

The invention has the advantages that:

the carbide slag adopted by the invention is a low-cost strong-alkaline waste, is dissolved in water to form an alkaline condition, and when the carbide slag is pretreated as a pretreatment method of grass biomass, the alkaline environment formed by the carbide slag can break the structure of the grass biomass, so that more fermentation substrates are provided for acid-producing microbial fermentation acid production. The invention realizes the resource utilization of grass biomass, expands the application of carbide slag and reduces the cost of producing VFAs by fermentation. More importantly, the produced VFAs are important fermentation intermediate products, have wide application value, can be used as a platform substance, can be used as an external carbon source to supplement the shortage of the carbon source in the process of nitrogen and phosphorus removal from sewage, can be further converted into energy substances such as methane, ethanol and the like, and can also be used for synthesizing long-chain fatty acid, paint and other chemical products and the like, thereby further realizing the resource utilization of the urban residual sludge. The invention provides a new way for realizing the resource utilization of grass biomass and also provides ideas for widening the application of the carbide slag.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.