阅读说明：本技术 蔗渣-糖蜜混合原料发酵乙醇联产沼气的方法 (Method for co-producing biogas by fermenting ethanol with bagasse-molasses mixed raw material ) 是由 谢君 樊美杉 于 2019-09-16 设计创作，主要内容包括：本发明公开了一种蔗渣-糖蜜混合原料发酵乙醇联产沼气的方法,包括如下步骤：S1.甘蔗渣预处理：将甘蔗渣粉碎,加入碱溶液,水洗、干燥,得到预处理后甘蔗渣；S2.混合发酵：取预处理后甘蔗渣和糖蜜,加入酵母活化液和纤维素酶,进行同步糖化发酵；所述预处理后甘蔗渣和糖蜜的质量以固液比为12％～48％称取；S3.厌氧发酵：同步糖化发酵后,移除乙醇,接入厌氧污泥,进行沼气发酵。本发明提供的以甘蔗渣和废糖蜜为原料联产乙醇和沼气的方法,提高了乙醇的产率、有效利用废液产生沼气。糖蜜减小了废液的粘度,使混合发酵后的废液能够进行高效厌氧发酵产沼气。不仅解决了乙醇发酵产率不高和废液难处理的问题,而且实现了废弃物资源利用化。(The invention discloses a method for co-producing biogas by fermenting ethanol with bagasse-molasses mixed raw materials, which comprises the following steps: s1, bagasse pretreatment: crushing bagasse, adding an alkali solution, washing with water, and drying to obtain pretreated bagasse; s2, mixed fermentation: taking the pretreated bagasse and molasses, adding yeast activation solution and cellulase, and performing simultaneous saccharification and fermentation; weighing the pretreated bagasse and molasses according to the solid-liquid ratio of 12-48%; s3, anaerobic fermentation: after synchronous saccharification and fermentation, removing ethanol, inoculating anaerobic sludge, and performing biogas fermentation. The method for co-producing ethanol and methane by using bagasse and waste molasses as raw materials improves the yield of ethanol and effectively utilizes waste liquid to produce methane. The molasses reduces the viscosity of the waste liquid, so that the waste liquid after mixed fermentation can be subjected to efficient anaerobic fermentation to produce methane. Not only solves the problems of low ethanol fermentation yield and difficult waste liquid treatment, but also realizes the utilization of waste resources.)

1. A method for co-producing biogas by fermenting ethanol with bagasse-molasses mixed raw materials is characterized by comprising the following steps:

S1, bagasse pretreatment: crushing bagasse, adding an alkali solution, washing with water, and drying to obtain pretreated bagasse;

S2, mixed fermentation: taking the pretreated bagasse and molasses, adding yeast activation solution and cellulase, and performing synchronous saccharification and fermentation to produce ethanol; weighing the pretreated bagasse and molasses according to the solid-liquid ratio of 12-48%;

S3, anaerobic fermentation: after synchronous saccharification and fermentation, removing ethanol, inoculating anaerobic sludge, and performing biogas fermentation.

2. The method as claimed in claim 1, wherein the pretreated bagasse and molasses are weighed at a solid-to-liquid ratio of 28-48%.

3. The method as claimed in claim 2, wherein the pretreated bagasse and molasses are weighed so that the solid-to-liquid ratio is 36-44%.

4. The method according to claim 1, wherein the mass ratio of the pretreated bagasse to the molasses is (0.3-3) to 1.

5. The method of claim 1, wherein the yeast activation solution is a saccharomyces cerevisiae activation solution.

6. The method according to claim 1, wherein the cellulase is used in an amount of 10-30 FPU/g of pretreated bagasse.

7. The method of claim 1, wherein the simultaneous saccharification and fermentation is carried out at a temperature of 30-38 ℃, a rotation speed of 100-200 rpm, and a time of 48-144 h.

8. The method of claim 1, wherein the anaerobic sludge is inoculated according to the ratio of inoculum to volatile solid in the substrate of (1-2) to 1.

Technical Field

The invention relates to the field of biomass energy, in particular to a method for jointly producing ethanol and methane by using bagasse and waste molasses as mixed fermentation raw materials.

Background

Bioethanol is a very considerable renewable energy source as an additive or a substitute for gasoline. The biogas is an ideal clean biofuel, and the biogas replaces the traditional fossil fuel to effectively avoid the problem of environmental pollution. Bioethanol and biogas can be used as automotive fuel, electricity or thermal energy, replacing fossil fuels. Currently, the method commonly used for producing bioethanol mainly uses lignocellulose biomass as raw material, and improves the concentration and yield of ethanol by mixing and fermenting with starch substances such as corn flour or wheat flour. In this process, food-type substances on which humans depend for survival are used.

Bagasse and molasses are by-products of the sugar industry. Bagasse is fibrous residue of sugarcane stalks obtained after sugarcane juice is extracted from sugarcane through crushing and squeezing, belongs to agricultural solid waste, and contains a large amount of cellulose, hemicellulose, lignin and the like. Molasses contains a large amount of fermentable sugars and is a good fermentation raw material.

When lignocellulose such as bagasse is used alone for fermentation, mass transfer is limited along with the increase of the concentration of the substrate, so that the stirring is difficult, the ethanol yield is not high, and the viscosity of the waste liquid after fermentation is high. The waste liquid restricts the development of biomass fuel, so that the Chemical Oxygen Demand (COD) is higher and the pollution problem is more serious.

therefore, there is a need for a new fermentation process that increases ethanol yield and can effectively treat subsequent waste streams.

Disclosure of Invention

the invention aims to overcome the defects that the ethanol yield is not high and waste liquid is difficult to treat when bagasse is used for producing ethanol by fermentation alone in the prior art, and provides a method for co-producing ethanol and methane by using bagasse and waste molasses as mixed fermentation raw materials.

In order to solve the technical problems, the invention adopts the technical scheme that:

A method for co-producing ethanol and biogas, comprising the steps of:

S1, bagasse pretreatment: crushing bagasse, adding an alkali solution, washing with water, and drying to obtain pretreated bagasse;

S2, mixed fermentation: taking the pretreated bagasse and molasses, adding yeast activation solution and cellulase, and performing synchronous saccharification and fermentation to produce ethanol; weighing the pretreated bagasse and molasses according to the solid-liquid ratio of 12-48%;

S3, anaerobic fermentation: after synchronous saccharification and fermentation, removing ethanol, inoculating anaerobic sludge, and performing biogas fermentation.

The invention provides a method for co-producing biofuel ethanol and biogas by mixing bagasse and molasses as fermentation raw materials. In the bagasse enzymatic hydrolysate, except sugar and a small amount of inorganic salt, the components are single; the molasses contains rich nutrient components such as nitrogen, phosphorus, vitamins and the like, can provide enough nutrient sources for yeast fermentation, improves the fluidity of a system, improves the yield of ethanol and reduces the viscosity of waste liquid. After the ethanol in the mixed fermentation waste liquid is recovered, the fermented concentrated grains are continuously subjected to anaerobic fermentation to produce the methane, so that the problem of difficulty in treatment of the waste liquid is solved, and the utilization of waste resources is realized. In addition, the molasses fermentation does not need pretreatment and pre-saccharification, so that the process flow of producing ethanol by mixed fermentation is reduced, and the production cost is reduced.

Preferably, the mass of the bagasse and the molasses after pretreatment in the step S2 is weighed with the solid-to-liquid ratio of 28% -48%.

More preferably, the mass of the bagasse and the molasses after pretreatment in step S2 is weighed with the solid-to-liquid ratio of 36% -44%.

Under the condition of lower solid-liquid ratio, namely the quality of the bagasse and the molasses is lower, the mixed fermentation of the bagasse and the molasses has no obvious advantage over the single fermentation of the bagasse; under the condition of higher solid-liquid ratio, the concentration and yield of ethanol produced by the mixed fermentation of bagasse and molasses are obviously improved compared with the single fermentation of bagasse, and the waste liquid obtained after the ethanol fermentation with higher solid-liquid ratio can further produce biogas, so that waste resources are reused.

preferably, the mass ratio of the bagasse after pretreatment to the molasses in the step S2 is (0.3-3) to 1.

as the proportion of molasses increases, the concentration and yield of ethanol also increase relatively, as molasses improves the fluidity of the system and provides sufficient nutrients for yeast growth. The advantage of the mass ratio of molasses to bagasse being 3:1 is not obvious compared with the mass ratio of molasses to bagasse being 1:1, so that a fermentation system in which the mass ratio of molasses to bagasse is 1:1 is preferred.

Preferably, the molasses in step S2 is waste molasses of sugar industry.

Preferably, the yeast activation solution in step S2 is a saccharomyces cerevisiae activation solution.

Preferably, the yeast concentration of the saccharomyces cerevisiae activation solution in the step S2 is 2.5-5 g/L.

More preferably, the yeast concentration of the saccharomyces cerevisiae activation solution in the step S2 is 3.3 g/L.

Preferably, the dosage of the cellulase in the step S2 is 10-30 FPU/g of the processed bagasse.

More preferably, the cellulase enzyme is used in step S2 at an amount of 15FPU/g of treated bagasse.

preferably, in the step S2, the temperature of the synchronous saccharification and fermentation is 30-38 ℃, the rotating speed is 100-200 rpm, and the time is 48-144 h.

More preferably, the temperature of the simultaneous saccharification and fermentation in the step S2 is 34 ℃, the rotation speed is 120rpm, and the time is 120 h.

Preferably, the anaerobic fermentation in step S3 is performed after the high load simultaneous saccharification and fermentation.

Preferably, the anaerobic sludge in the step S3 is inoculated according to the ratio of the inoculum to the volatile solid in the substrate being (1-2) to 1.

More preferably, the anaerobic sludge in step S3 is inoculated at a ratio of inoculum to volatile solids in the substrate of 1: 1.

Preferably, the water washing in step S1 is water washing to neutral.

Preferably, the drying in step S1 is drying to a constant weight.

preferably, the molasses in step S2 is waste molasses.

Preferably, the alkali solution in step S1 is a NaOH solution.

Preferably, the concentration of the NaOH solution in step S1 is 2%.

preferably, the NaOH solution is added in step S1 according to a solid-to-liquid ratio of 1: 20.

preferably, the NaOH solution is added in step S1 and then placed at 80 ℃ for 2 h.

preferably, the crushing in step S1 is to crush the bagasse to 40-60 mesh.

The method for co-producing the ethanol and the methane comprises the following specific steps:

(1) Pretreatment of bagasse raw materials: weighing absolutely dry bagasse raw materials, adding 2% NaOH solution according to a solid-liquid ratio of 1: 20, processing at 80 ℃ for 2h, and then washing with water to be neutral to obtain pretreated bagasse;

(2) Mixing and fermenting: weighing pretreated bagasse and waste molasses according to the solid-to-liquid ratio of 12-48% (W/V) and the ratio of (0.3-3) to 1, adding yeast activation solution with the initial yeast cell concentration of 3.3g/L and 15FPU (fermented starch Unit) of cellulase according to the amount of the pretreated bagasse per gram, controlling the temperature of a reaction system to be 34 ℃ and the rotating speed to be 120rpm, and performing synchronous saccharification and fermentation to produce ethanol;

(3) Anaerobic fermentation to produce methane: after the synchronous saccharification and fermentation is finished, removing ethanol, and inoculating anaerobic sludge according to the ratio of 1:1 of the inoculum to volatile solids in the substrate for biogas fermentation.

Compared with the prior art, the invention has the beneficial effects that:

The method for co-producing ethanol and biogas by taking bagasse and molasses as raw materials improves the yield of ethanol, reduces the viscosity of the waste liquid by using molasses, enables the waste liquid after mixed fermentation to be subjected to efficient anaerobic fermentation to produce biogas, and effectively removes VS and COD. Not only solves the problems of low ethanol fermentation yield and difficult waste liquid treatment, but also realizes the utilization of waste resources.

Detailed Description

The present invention will be further described with reference to specific embodiments, but the embodiments of the present invention are not limited thereto. The raw materials in the examples are all commercially available; reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Bagasse pretreatment: weighing absolutely dry bagasse raw materials, adding 2% NaOH solution according to a solid-liquid ratio of 1: 20, processing at 80 ℃ for 2h, and then washing with water to be neutral to obtain the pretreated bagasse.

the molasses is waste molasses, the cellulase is obtained from Shanghai leaf Biotechnology GmbH, the Saccharomyces cerevisiae is obtained from Angel Yeast GmbH, the ethanol content in the reaction solution is analyzed by high performance liquid chromatography, and the methane content is analyzed by AMPTS-II-full-automatic methane potential testing system.

Preparation of yeast activation liquid: weighing 2g of glucose, dissolving in 100mL of deionized water, inoculating 6.6g of yeast powder, and activating on a shaker at 160 rpm: firstly, 36 ℃ for 10 min; ② 34 ℃ and 1 h.

The ethanol yield was calculated as follows: