Method for preparing composite carbon source based on biodiesel byproduct

Abstract

The invention discloses a method for preparing a composite carbon source based on biodiesel by-products, which comprises the following steps: carrying out primary evaporation on the biodiesel by-products to obtain a primary concentrate, carrying out secondary evaporation on the primary concentrate to obtain a secondary concentrate and low-concentration methanol, adding protease and amylase into the secondary concentrate to carry out hydrolysis, and carrying out secondary evaporation on the low-concentration methanol to obtain the composite carbon source. Stirring at 40-50 DEG C for more than 24 hours to hydrolyze protein and starch in the secondary concentrate to obtain a second carbon source; and uniformly mixing low-concentration methanol, the second carbon source and the adjusting carbon source to obtain the target carbon source. According to the method, the biodiesel by-product is continuously evaporated twice, the methanol separation efficiency is improved, methanol in the by-product can be recycled to the maximum extent, the recycled high-concentration methanol can be used as the raw material methanol of the biodiesel, the production cost of the biodiesel is reduced, and the economic benefits of enterprises are improved; and the evaporated concentrate can be used as a carbon source after being hydrolyzed, so that the recycling of byproducts is realized, and the economic benefits of enterprises are further improved.

Description

Technical Field

[0001] The present invention relates to the field of by - product treatment of biodiesel, and particularly to a method for preparing a composite carbon source based on biodiesel by - products. Background Art

[0002] The main component of biodiesel is fatty acid methyl ester, which is obtained by mixing raw material oil with methanol and carrying out an esterification reaction under the action of a catalyst. The physical and chemical properties of fatty acid methyl ester are very close to or even better than those of diesel, making it an ideal substitute for diesel and capable of reducing diesel consumption to a certain extent. Currently, in China, mainly waste oils and fats (such as recycled cooking oil, swill waste oil, frying oil, and roast duck oil, etc.) are used as the main raw materials, and lipase is used as the catalyst to carry out continuous esterification reaction between waste oils and fats and methanol or ethanol. However, during this process, a large number of by - products are often accompanied. These by - products contain organic substances such as glycerol, methanol, soluble protein, and starch. If not reasonably treated, it will not only lead to waste of resources but also pollute the environment. In addition, swill waste oil mainly comes from kitchen wastewater, and the wastewater after oil extraction treatment will still pollute the environment. Summary of the Invention

[0003] In view of this, the present invention provides a method for preparing a composite carbon source based on biodiesel by - products. This method can not only recover most of the methanol in the by - products as raw materials for biodiesel but also obtain target carbon sources with different COD concentrations, realizing the maximum utilization of biodiesel by - products as resources, energy conservation, and emission reduction.

[0004] To achieve the above - mentioned purpose, the present invention adopts the following technical solutions: The method for preparing a composite carbon source based on biodiesel by - products according to the present invention includes the following steps: Perform primary evaporation on the biodiesel by - product to obtain a primary concentrate; among them, the evaporated methanol - water mixed steam is condensed to obtain high - concentration methanol with a concentration of ≥75%, which is used as the raw material for the enzymatic catalysis section of biodiesel, thereby reducing the cost of the enzymatic catalysis section of biodiesel; Perform secondary evaporation on the primary concentrate to obtain a secondary concentrate and methanol - water steam. The methanol - water steam is condensed to obtain low - concentration methanol with a methanol concentration of ≤20% in the low - concentration methanol, which is used as the first carbon source; Add protease and amylase to the secondary concentrate for hydrolysis, and stir at 40 - 50 °C for more than 24 h to hydrolyze the protein and starch in the secondary concentrate into polypeptides or starch sugars to obtain the second carbon source; Mix the first carbon source, the second carbon source, and the regulating carbon source evenly to obtain a target carbon source with COD ≥ 3.0×10 5 mg / L; among them, the addition amount of the regulating carbon source is greater than or equal to 0%.

[0005] The beneficial effects are as follows: The present invention first performs continuous two - stage evaporation on the biodiesel by - products, which can maximize the recovery of methanol in the by - products. The recovered high - concentration methanol can be used as the raw material methanol for biodiesel, reducing the production cost of biodiesel and improving the economic benefits of the enterprise. The concentrated product after evaporation can be used as a carbon source after hydrolysis, thus realizing the resource utilization of the by - products and further improving the economic benefits of the enterprise.

[0006] Preferably, the first - stage evaporation is atmospheric - pressure stirring evaporation at a temperature of 80 - 90°C; the second - stage evaporation is vacuum evaporation at a pressure of -(0.03 - 0.04) MPa and a temperature of 80 - 100°C.

[0007] Preferably, when hydrolyzing the second - stage concentrate, a part of the kitchen waste water after oil separation treatment is added to the second - stage concentrate, and protease and amylase are used to hydrolyze the mixture of the second - stage concentrate and the kitchen waste water. In actual production, the kitchen waste water after oil extraction treatment can be hydrolyzed to realize the resource utilization of the kitchen waste water.

[0008] Preferably, the regulating carbon source is glycerol. Of course, in actual production, glucose or the like can also be used as the regulating carbon source to regulate the first carbon source and the second carbon source to obtain the target carbon source.

[0009] Compared with the prior art, the advantages of the present invention are as follows: The present invention first performs continuous two - stage evaporation on the biodiesel by - products, which can maximize the recovery of methanol in the by - products. The recovered high - concentration methanol can be used as the raw material methanol for biodiesel, reducing the production cost of biodiesel and improving the economic benefits of the enterprise. The concentrated product after evaporation can be used as a carbon source after hydrolysis, realizing the resource utilization of the by - products and further improving the economic benefits of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is the process flow chart of the present invention.

[0011] Figure 2 is the second process flow chart of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The technical solutions of the present invention will be described in more detail below. It should be noted that the protease and lipase in the present invention are both commercially available products.

[0013] The present invention provides a method for preparing a composite carbon source based on biodiesel by - products. The composite carbon source uses biodiesel by - products as the main carbon source and glycerol (preferably crude glycerol to reduce costs) as the regulating carbon source, and then obtains a COD≥3.0×10 5Target carbon sources of mg / L and above to meet the needs of different manufacturers (especially urban sewage treatment plants), which can be used as supplementary carbon sources for urban sewage treatment plants, and also realize the resource utilization of biodiesel by-products, improving the economic benefits of biodiesel production enterprises. The specific contents are as follows: First step, pump the biodiesel by-product into a vacuum distillation reactor at a certain flow rate for primary evaporation, and the evaporated primary concentrate contains a small amount of methanol. In addition, during the evaporation process, a large amount of gas phase is generated, and the gas phase can be condensed to obtain high-concentration methanol (i.e., methanol with a volume fraction ≥ 75%), which can be used as a raw material for biodiesel to prepare biodiesel, thereby reducing production costs and improving economic benefits; During primary evaporation, atmospheric pressure stirring evaporation is adopted, and the temperature is controlled at 80 - 90 °C, which not only improves the evaporation rate of methanol but also protects the glycerol in the biodiesel by-product; Second step, perform secondary evaporation on the primary concentrate after primary evaporation. Secondary evaporation uses vacuum distillation, with a pressure of -(0.03 - 0.04) MPa and a temperature of 80 - 100 °C; The evaporated gas phase is condensed to obtain low-concentration methanol (i.e., methanol with a volume fraction ≤ 20%). After evaporation, a secondary concentrate is obtained. The secondary concentrate includes water, glycerol, and a small amount of protein and starch, and the mass fractions of water, glycerol, protein, and starch are approximately 53%, 40%, 4%, and 3% respectively; The present invention adopts a continuous distillation method combining atmospheric pressure and vacuum, which can effectively improve the separation efficiency of methanol in the by-product, and thus recover methanol to the greatest extent. The recovered high-concentration methanol can be reused in the biodiesel preparation process; the recovered low-concentration methanol can be used as the first carbon source to adjust the COD concentration of the target carbon source to meet the different needs of users; Third step, add 2 - 4% protease and 2 - 5% amylase to the secondary concentrate after secondary evaporation, and stir at 40 - 50 °C for 24 - 48 h to hydrolyze the protein and starch in the secondary concentrate to obtain the second carbon source; Fourth step, mix the first carbon source, the second carbon source, and the regulating carbon source (the regulating carbon source is preferably glycerol) evenly to obtain a target carbon source with a COD ≥ 3.0×10 5 mg / L. The dosages of the first carbon source, the second carbon source, and glycerol in the target carbon source are all ≥ 0%, and can be specifically adjusted according to user needs until the target carbon source with the concentration required by the user is obtained.

[0014] In actual production, if there is kitchen waste swill, the kitchen waste swill and the secondary concentrate can be hydrolyzed simultaneously to obtain the second carbon source based on the secondary concentrate and the kitchen waste swill. Specifically: before hydrolysis, the kitchen waste swill is subjected to oil extraction (the swill oil is used as a raw material for biodiesel) and sterilization treatment in sequence, and then hydrolyzed together with the secondary concentrate; After hydrolysis is completed, the second concentrate is filtered to remove impurities, and then the second carbon source, the first carbon source and glycerol are compounded according to user requirements to obtain a target carbon source with a COD ≥ 3.0×10 5 mg / L, as specifically shown in Figure 2 .

[0015] In the present invention, the biodiesel by-products are subjected to continuous atmospheric and vacuum distillation to obtain glycerol concentrate, high-concentration methanol and low-concentration methanol. The high-concentration methanol can be used as a raw material for biodiesel; after the glycerol concentrate is enzymatically hydrolyzed and blended with low-concentration methanol (glycerol can be added if necessary), carbon sources with different COD concentrations can be achieved, realizing the resource utilization of biodiesel by-products, providing low-cost carbon sources for users, and saving energy and reducing emissions. In the process of the present invention, kitchen waste water can be introduced to realize the resource utilization of kitchen waste water, further reducing the cost of the target carbon source, saving energy and protecting the environment, and improving the economic benefits of production enterprises.

Claims

1. A method for preparing a composite carbon source based on biodiesel byproducts, characterized in that: The composite carbon source production method comprises the following contents: The biodiesel byproduct is evaporated once to obtain a concentrate; wherein the evaporated methanol water vapor is condensed to obtain high-concentration methanol, the concentration of the high-concentration methanol being ≥75%, which is used as a raw material for biodiesel; The primary concentrate is evaporated twice to obtain a secondary concentrate and methanol vapor, and the methanol vapor is condensed to obtain low-concentration methanol, wherein the methanol concentration in the low-concentration methanol is ≤20%, which is used as the first carbon source; Adding protease and amylase to the secondary concentrate for hydrolysis, stirring at 40-50° C. for more than 24 hours, so that the protein and starch in the secondary concentrate are hydrolyzed to obtain a second carbon source; The first carbon source, the second carbon source and the regulating carbon source are mixed evenly to obtain a COD ≥ 3.0 × 10 5 mg / L of target carbon source; wherein the amount of carbon source added is adjusted to be greater than or equal to 0%.

2. The method for preparing a composite carbon source based on biodiesel byproducts according to claim 1, characterized in that: The first evaporation is stirring evaporation at normal pressure, and the temperature is 80-90°C; the second evaporation is reduced pressure evaporation, and the pressure is -(0.03-0.04)MPa, and the temperature is 80-100°C.

3. The method for preparing a composite carbon source based on biodiesel byproducts according to claim 1, characterized in that: When the secondary concentrate is hydrolyzed, the food wastewater treated with oil separation is added to the secondary concentrate, and the mixed solution of the secondary concentrate and the food wastewater is hydrolyzed by using protease and amylase.

4. The method for preparing a composite carbon source based on biodiesel byproducts according to claim 1, characterized in that: The adjusted carbon source is crude glycerol.

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