Method for separating mycelia and purifying lactic acid in L-lactic acid fermentation liquor
Through multiple centrifugation methods and pH adjustment methods, the problem of high cost of mycelium separation process in L-lactic acid fermentation broth is solved, efficient mycelium separation and lactic acid purification are achieved, and energy and lime milk consumption is reduced. , improve product recycling rate and production efficiency.
Patent Information
- Application Number
- CN202411332063.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-24
- Publication Date
- 2024-12-27
AI Technical Summary
The mycelium separation process in the existing L-lactic acid fermentation broth is costly, requiring a large amount of steam heating, lime milk to adjust pH, flocculants and filter aids, resulting in increased energy consumption and auxiliary material consumption, affecting product quality and production efficiency.
Mycelium separation and lactic acid purification were performed by multiple centrifugation. By adjusting the pH value to 7.0-7.5 and heating to 55-65°C, the mycelium was separated by centrifuge to avoid the use of flocculants and filter aids, and the process was simplified. process to reduce costs.
It improves the recovery rate of L-lactic acid, saves energy consumption, reduces the use of lime milk and steam, reduces production costs, and increases the recovery rate of mycelium protein to 100%, which meets the quality requirements of the food and medicine fields.
Smart Images
Figure CN119191970A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of L-lactic acid production, and particularly relates to a method for separating mycelium from L-lactic acid fermentation liquid and purifying lactic acid. Background Art
[0002] L-lactic acid is an important food raw material with good water solubility and biocompatibility, and can participate in normal human metabolism. L-lactic acid is often used as an additive and product modifier in the food and pharmaceutical fields, and plays an important role in the production of pharmaceutical intermediates and polylactic acid.
[0003] With the implementation of the national plastic restriction and ban, the market potential of polylactic acid biodegradable materials is huge, with significant economic, social and environmental benefits. Lactic acid, as the raw material for the production of polylactic acid (PLA), especially L-lactic acid, as the raw material for the production of biodegradable material polylactic acid, has become the focus of future development in the field of environmental protection. It can be seen that L-lactic acid is widely used in food, medicine, chemical industry and new materials.
[0004] At present, the industrial production method of L-lactic acid mainly uses starch and various sugars as raw materials, and produces food-grade and material-grade high-purity lactic acid products through biological fermentation and refining. However, the cost of L-lactic acid production is relatively high. At present, when producing L-lactic acid at home and abroad, the removal of mycelium in the fermentation broth has always been to add lime milk to inactivate the mycelium after the fermentation tank is stopped, and then the fermentation broth is steam-heated to above 90°C, and the pH value is adjusted to above 10.5 again, and then a completely hydrolyzed flocculant is added to flocculate and settle the mycelium, and finally the mycelium is separated from the fermentation broth by a plate and frame filter press. This process first requires a large amount of steam heating, lime milk to adjust the pH value, flocculants to flocculate the mycelium, filter aids during plate and frame filtration, and concentrated sulfuric acid acid hydrolysis of the clear liquid, thereby increasing the consumption of energy and auxiliary materials, and the separation cost is high. Therefore, the separation process of mycelium in L-lactic acid fermentation broth is crucial to the quality and production cost of L-lactic acid products. Summary of the invention
[0005] In view of this, the present invention proposes a method for preparing mycelium from L-lactic acid fermentation broth, which is simple to operate and reduces costs.
[0006] In order to solve the above technical problems, the following technical solutions are proposed:
[0007] The present invention provides a method for separating mycelium from L-lactic acid fermentation broth and purifying lactic acid, comprising the following steps:
[0008] The L-lactic acid fermentation liquid is centrifuged to obtain an L-lactic acid fermentation clear liquid; the number of centrifugation is ≥3.
[0009] Preferably, the centrifugation includes a first centrifugation, a second centrifugation and a third centrifugation; the centrifugation is performed in the following manner: the L-lactic acid fermentation broth is subjected to a first centrifugation to obtain mycelium; the mycelium is mixed with water and then subjected to a second centrifugation; and the supernatant obtained from the second centrifugation is subjected to a third centrifugation.
[0010] Preferably, the first centrifugation time is 0.5-1.5 h, and the rotation speed is 8000-12000 rpm; the second centrifugation time is 5.0-6.0 h, and the rotation speed is 6000-10000 rpm; the third centrifugation time is 0.5-1.5 h, and the rotation speed is 8000-12000 rpm.
[0011] Preferably, the pH value of the L-lactic acid fermentation broth to be centrifuged is 7.0-7.5.
[0012] Preferably, the method for obtaining the L-lactic acid fermentation broth having a pH value of 7.0 to 7.5 comprises:
[0013] Performing a first pH adjustment on the L-lactic acid fermentation broth to obtain a first adjusted broth having a pH value of 7.0 to 7.5;
[0014] heating the first regulating liquid to obtain a heated liquid;
[0015] The pH value of the heated liquid is adjusted for the second time.
[0016] Preferably, the agent used to adjust the pH value includes milk of lime.
[0017] Preferably, the heating temperature is 55-65°C.
[0018] Beneficial effects of the invention: The invention provides a method for separating mycelium from L-lactic acid fermentation broth and purifying lactic acid, comprising the following steps:
[0019] The L-lactic acid fermentation liquid is centrifuged to obtain an L-lactic acid fermentation clear liquid; the number of centrifugation is ≥3.
[0020] The present invention separates the L-lactic acid fermentation clear liquid and mycelium by centrifugation. The present invention adopts centrifugation to replace the lactic acid precipitation filtration purification process, avoids the addition of concentrated sulfuric acid, flocculants and filter aids, simplifies the process and reduces costs. After the first centrifugation of the present invention, the dense phase fungus residue (i.e., mycelium) still contains a certain concentration of lactic acid, the dense phase fungus residue is subjected to a second centrifugation again, and the supernatant obtained by the second centrifugation is subjected to a third centrifugation to recover the lactic acid in the fungus residue as much as possible; through the first centrifugation, the second centrifugation and the third centrifugation, the recovery rate of L-lactic acid is improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1This is the original flocculation filtration process flow chart for separation and purification of mycelium in L-lactic acid fermentation broth;
[0022] Figure 2 This is a process flow chart for separation and purification of mycelium from L-lactic acid fermentation broth according to Example 1 and Example 2 of the present invention. DETAILED DESCRIPTION
[0023] The present invention provides a method for separating mycelium from L-lactic acid fermentation broth and purifying lactic acid, comprising the following steps:
[0024] The L-lactic acid fermentation liquid is centrifuged to obtain an L-lactic acid fermentation clear liquid; the number of centrifugation is ≥3.
[0025] In the present invention, there is no particular limitation on the source of the L-lactic acid fermentation broth, and conventional products may be used.
[0026] In the present invention, the process before centrifugation preferably further includes: adjusting the pH value of the L-lactic acid fermentation broth for the first time to obtain a first adjusting liquid with a pH value of 7.0 to 7.5; the method for obtaining the L-lactic acid fermentation broth with a pH value of 7.0 to 7.5 of the present invention preferably includes: adjusting the pH value of the L-lactic acid fermentation broth for the first time to obtain a first adjusting liquid with a pH value of 7.0 to 7.5; heating the first adjusting liquid to obtain a heated liquid; and adjusting the pH value of the heated liquid for the second time. The pH adjusting agent used in the first adjusting liquid with a pH value of 7.0 to 7.5 of the present invention preferably includes lime milk, which completely inactivates the mycelium in the fermentation broth by adjusting the pH value, and the lime milk can also precipitate and remove impurities such as protein and sugar in the fermentation broth by adjusting the pH. The pH value of the first adjusting liquid is preferably 7.0 to 7.5, and more preferably 7.0 to 7.2. The second pH adjustment of the present invention is preferably to 7.0-7.5, and the reagent used for adjusting the pH preferably includes lime milk. Since the heating operation will release L-lactic acid in the mycelium, the pH value of the L-lactic acid fermentation liquid will decrease, so the pH adjustment is required for the second time. The effect of adjusting the pH value to 7.0-7.5 is to kill the mycelium. In the traditional lactic acid precipitation filtration purification process, the pH value needs to be adjusted to about 10.5 because of the need for bacterial flocculation and filtration. A high pH value is conducive to bacterial flocculation and filtration; while the technical solution of the present invention does not require bacterial flocculation and filtration, so the pH value can be adjusted to 7.0-7.5, saving the amount of reagents used to adjust the pH value.
[0027] In the present invention, the heating temperature is preferably 55-65°C, more preferably 60°C, and the heating method is preferably steam heating; the heating is used to release the L-lactic acid in the mycelium through heating, thereby increasing the yield of L-lactic acid. In the traditional lactic acid precipitation filtration purification process, the fermentation broth is heated from 52°C to 90°C because the bacteria can release the lactic acid in the body when heated, and high temperature makes flocculation easier, and the steam consumption is high. The centrifugal process used in the present invention only needs to be heated to 60°C, which reduces the steam consumption, and every 100m 3 The heating of the fermentation liquid is reduced from the original 6.0t steam to less than 2.0t steam, which saves energy. The present invention has no special restrictions on the equipment for adjusting the pH value and heating application, and conventional equipment can be used. In an embodiment of the present invention, the equipment for adjusting the pH value and heating application is preferably a post-fermentation tank. The post-fermentation tank of the present invention is a storage tank for the fermentation product obtained after fermentation.
[0028] After the second adjustment of the pH value, the present invention preferably centrifuges the L-lactic acid fermentation broth obtained after the second adjustment of the pH value to obtain an L-lactic acid fermentation clear liquid. The number of centrifugation times of the present invention is ≥3, and more preferably 3 times; the method of centrifugation of the present invention is preferably: the L-lactic acid fermentation broth is subjected to a first centrifugation to obtain mycelium; the mycelium is mixed with water and then subjected to a second centrifugation; the supernatant obtained by the second centrifugation is subjected to a third centrifugation. The time of the first centrifugation of the present invention is preferably 0.5 to 1.5 hours, more preferably 1.0 to 1.5 hours, and more preferably 1.5 hours; the rotation speed is preferably 8000 to 12000 rpm, more preferably 9000 to 11000 rpm, and more preferably 12000 rpm; the equipment used for the first centrifugation of the present invention preferably includes a disc centrifuge; mycelium and clear liquid are obtained after the first centrifugation; the clear liquid is returned to the fermentation liquid storage tank. The mycelium and water are preferably mixed for a second centrifugation; the volume ratio of mycelium to water during the mixing is preferably 1:2; the present invention preferably uses process water for the water to reduce the use of fresh tap water, and the process water is preferably evaporation condensation water of the production system to achieve water recycling. The time of the second centrifugation of the present invention is preferably 5.0-6.0h, more preferably 5.5-6.0h, more preferably 6.0h; the rotation speed is preferably 6000-10000rpm, more preferably 8000-10000rpm, more preferably 10000rpm; the equipment used for the second centrifugation preferably includes a horizontal screw centrifuge. The time of the third centrifugation of the present invention is preferably 0.5-1.5h, more preferably 1.0-1.5h, more preferably 1.5h; the rotation speed is preferably 8000-12000rpm, more preferably 9000-11000rpm, more preferably 12000rpm; the equipment used for the third centrifugation of the present invention preferably includes a disc centrifuge; the feed flow rate of the first centrifugation, the second centrifugation and the third centrifugation is less than the maximum feed flow of the centrifuge. After the third centrifugation, mycelium and L-lactic acid fermentation supernatant are obtained. The present invention combines the supernatant obtained by the first centrifugation and the L-lactic acid fermentation supernatant obtained by the third centrifugation to obtain a crude L-lactic acid extract, and purifies the crude L-lactic acid extract to obtain L-lactic acid. The three centrifugations of the present invention increase the yield of the L-lactic acid fermentation supernatant, so that the yield of the L-lactic acid fermentation supernatant reaches 99%, while saving energy and reducing the intensity of operation.
[0029] The traditional separation method requires the addition of a large amount of lime milk to reach an excessively high pH value and the addition of a large amount of filter aids and flocculants, so that the mycelium protein content in the fungus residue is very low and can basically only be treated as solid waste; while in the present invention, the amount of lime milk added is low, and no flocculants or filter aids are added. The obtained fungus residue is only the bacteria brought into the fermentation liquid, and the bacteria can be used as protein feed to increase added value, and the protein recovery rate of the bacteria is increased to 100%.
[0030] In order to further illustrate the present invention, the technical solution provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.
[0031] The process flow of separation and purification of mycelium from L-lactic acid fermentation broth of Comparative Example 1 is shown in Figure 1 The process flow chart of L-lactic acid fermentation broth mycelium separation and L-lactic acid purification in Examples 1 to 2 is shown in Figure 2 .
[0032] Example 1
[0033] The steps of a process for separating mycelium from L-lactic acid fermentation liquid and purifying L-lactic acid are as follows:
[0034] 1. Put the L-lactic acid fermentation liquid obtained from the fermentation tank into a new fermentation tank, and then add lime milk to adjust the pH value to 7.0; every 100m 3 55 kg of lime milk was added to the L-lactic acid fermentation liquid after pH adjustment.
[0035] 2. Set the volume to 100m 3 , L-lactic acid fermentation liquid with a pH value of 7.0 is heated to 60°C by a plate heat exchanger through a pump. 3 The amount of steam used in the L-lactic acid fermentation liquid after pH adjustment is 1900 kg.
[0036] 3. Adjust the pH value of the heated L-lactic acid fermentation liquid to 7.0 with lime milk again. 3 5 kg of lime milk was added to the heated L-lactic acid fermentation liquid.
[0037] 4. Start the disc centrifuge, and centrifuge the L-lactic acid fermentation broth obtained in step 3 at a flow rate of 814.7 L / h. The first clear liquid obtained by centrifugation enters the clear liquid tank, and the mycelium obtained by centrifugation enters the mycelium preparation tank; the centrifugal speed of the disc centrifuge is 12000 rpm, the centrifugal time is 1 hour, and the centrifugal temperature is 60°C.
[0038] 5. After the separation in step 4 is completed, the disc centrifuge is stopped. The collected mycelia in the mycelia preparation tank is diluted with hot water to obtain a mycelia dilution liquid.
[0039] 6. After stopping the disc centrifuge, start the horizontal screw centrifuge for squeezing centrifugation. The mycelium dilution obtained in step 5 enters the horizontal screw centrifuge at a flow rate of 50L / h for squeezing centrifugation. The speed of squeezing centrifugation is 10000rpm, the time is 5h, and the centrifugation temperature is 60°C. After the squeezing centrifugation is completed, stop the horizontal screw centrifuge. The clear liquid obtained by squeezing centrifugation is returned to the post-fermentation tank (i.e., the fermentation liquid storage tank) and then disc centrifuged. The speed of the disc centrifugation is 12000rpm, the centrifugation time is 1.0h, and the centrifugation temperature is 65°C to obtain the second clear liquid.
[0040] The mycelium obtained by pressing and centrifugation is concentrated for processing.
[0041] The second clear liquid enters the clear liquid tank, and the first clear liquid of step 4 and the second clear liquid of step 6 are combined to obtain the crude L-lactic acid extract, which needs to be purified later. The mycelium obtained by disc centrifugation, i.e., the residue, can be used as a biological fertilizer.
[0042] Example 2
[0043] The steps of a process for separating mycelium from L-lactic acid fermentation liquid and purifying L-lactic acid are as follows:
[0044] 1. Put the L-lactic acid fermentation liquid obtained from the fermentation tank into a new fermentation tank, and then add lime milk to adjust the pH value to 7.0. 3 55 kg of lime milk was added to the L-lactic acid fermentation liquid after pH adjustment.
[0045] 2. Set the volume to 100m 3 , the L-lactic acid fermentation liquid pump with a pH value of 7.0 is heated by steam using a plate heat exchanger to 65°C per 100m 3 2000kg of steam is used for L-lactic acid fermentation liquid.
[0046] 3. Adjust the pH value of the heated fermented liquid to 7.0 with lime milk again. 3 5 kg of lime milk was added to the heated L-lactic acid fermentation liquid.
[0047] 4. Start the disc centrifuge and centrifuge the fermentation liquid obtained in step 3 at a flow rate of 1000.4 L / h. The first clear liquid obtained by centrifugation enters the clear liquid tank, and the mycelium obtained by centrifugation enters the mycelium preparation tank. The centrifugal speed of the disc centrifuge is 12000 rpm, the centrifugal time is 1.0 h, and the centrifugal temperature is 65°C.
[0048] 5. After the separation in step 4 is completed, the disc centrifuge is stopped. The collected mycelium is diluted with hot water to obtain a mycelium dilution liquid, which is then put into a horizontal screw centrifuge for squeezing and centrifugation.
[0049] 6. Start the horizontal screw centrifuge for squeezing and centrifuging. Specifically, the mycelium dilution obtained in step 5 enters the horizontal screw centrifuge at a flow rate of 40 L / h for squeezing and centrifuging. The speed of squeezing and centrifuging is 10000 rpm, the time is 6 hours, and the centrifugal temperature is 59°C. After the squeezing and centrifuging is completed, the horizontal screw centrifuge is stopped. The mycelium obtained by squeezing and centrifuging is collected for centralized treatment. The clear liquid obtained by squeezing and centrifuging is returned to the post-fermentation tank (i.e., the fermentation liquid storage tank) and then disc centrifuged. The speed of the disc centrifuge is 12000 rpm, the centrifugal time is 1.0 hour, and the centrifugal temperature is 65°C to obtain the second clear liquid.
[0050] The second clear liquid enters the clear liquid tank, and the first clear liquid of step 4 and the second clear liquid of step 6 are combined to obtain the crude L-lactic acid extract, which needs to be purified later. The mycelium obtained by disc centrifugation, i.e., the residue, can be used as a biological fertilizer.
[0051] Comparative Example 1
[0052] The specific process of separation and purification of mycelium from L-lactic acid fermentation broth is as follows:
[0053] 1. Put the L-lactic acid fermentation liquid obtained from the fermentation tank into a new fermentation tank, and then add lime milk to adjust the pH value to 10.5; every 100m 3 260 kg of lime milk was added to the L-lactic acid fermentation liquid after pH adjustment.
[0054] 2. 100m 3 The L-lactic acid fermentation liquid with a pH value of 10.5 is heated to 90°C by steam through a pump using a plate heat exchanger. 3 The L-lactic acid fermentation liquid after pH adjustment uses about 6t of steam;
[0055] 3. Adjust the pH value of the heated fermented liquid to 10.5 again with lime milk; 3 After adjusting the pH of the L-lactic acid fermentation liquid, a total of 260 kg of lime milk needs to be added in step 1 and step 3;
[0056] 4. Add 100m3 of pre-hydrolyzed flocculant 3 In the L-lactic acid fermentation liquid with a pH value of 10.5, the mycelium was flocculated and settled. 3 2kg of flocculant is applied to L-lactic acid fermentation broth;
[0057] 5. The flocculated fermentation liquid obtained in step 4 is filtered using a plate and frame filter press, and a filter aid is added to the plate and frame filter press in an amount of 300 kg;
[0058] 6. In step 5, the supernatant and mycelium are obtained by filtration. The supernatant enters the clear liquid tank, and the mycelium is waste.
[0059] The calculation formula of the supernatant yield is: supernatant yield = the total amount of lactic acid in the supernatant finally obtained after centrifugation / the total amount of lactic acid in the initial fermentation liquid before treatment.
[0060] The comparison results of the methods of Examples 1 to 2 of the present invention and Comparative Example 1 are shown in Table 1. According to Table 1, the clear liquid yield of the method for separating mycelium and purifying lactic acid in L-lactic acid fermentation broth provided by the present invention is increased to 99.0%, which is much higher than 98.5% of Comparative Example 1, and is higher than the domestic industry level.
[0061] The conventional method of comparative example 1 requires steam to heat the fermentation liquid from 52°C to 90°C, while the method of the present invention only requires heating the fermentation liquid to 60°C, thereby reducing steam consumption. The method for separating mycelium from L-lactic acid fermentation liquid and purifying lactic acid provided by the present invention reduces steam consumption. 3 The heating amount of the fermentation liquid was reduced from 6.0 t in Comparative Example 1 to less than 2.0 t.
[0062] The method for separating mycelium from L-lactic acid fermentation broth and purifying lactic acid provided by the present invention does not require the addition of flocculants and filter aids. The present invention only needs to adjust the pH value to about 7.0 to kill the mycelium, while the process of comparative example 1 needs to adjust the pH value of the fermentation broth to about 10.5. The method of the present invention reduces the consumption of lime milk. 3 The amount of lime milk reduced by the fermentation liquid is reduced from 0.26t of lime milk consumed in Comparative Example 1 to 0.06t in the present invention.
[0063] The method for separating mycelium from L-lactic acid fermentation broth and purifying lactic acid provided by the present invention does not require a flocculation process or a filtration process, and only requires centrifugation, thereby saving energy, simplifying the operating procedures, and further reducing the number of on-site personnel and operators. The traditional method of comparative example 1 requires 3 DCS personnel and 4 on-site operators (per shift); the present invention only requires 1 DCS personnel and 1 on-site inspection personnel. At the same time, the method of comparative example 1 requires the preparation of filter aids and the unloading of mycelium filter cakes, while the present invention does not require the addition of filter aids and does not have a plate-and-frame filtration process, so there is no need for plate-and-frame unloading by personnel, and the labor load is greatly reduced.
[0064] Table 1 Comparison results of Examples 1 to 2 and Comparative Example 1
[0065]
[0066] The results of the supernatants and mycelia obtained in Examples 1 to 2 and Comparative Example 1 are shown in Table 2. According to Table 2, the supernatants of Examples 1 and 2 have low chroma and clear feed liquids, which fully meet the process requirements. The mycelia content and dry matter content were determined by the drying method, the chroma was determined by the platinum-cobalt colorimetric method, and the lactic acid concentration was determined by the high performance liquid chromatography method.
[0067] Table 2 Determination results of supernatants and mycelium obtained in Examples 1 to 2 and Comparative Example 1
[0068]
[0069]
[0070] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A method for separating mycelium from L-lactic acid fermentation broth and purifying lactic acid, characterized in that: The steps include: The L-lactic acid fermentation liquid is centrifuged to obtain an L-lactic acid fermentation clear liquid; the number of centrifugation is ≥3.
2. The method according to claim 1, characterized in that The centrifugation includes a first centrifugation, a second centrifugation and a third centrifugation; the centrifugation method is: performing a first centrifugation on the L-lactic acid fermentation liquid to obtain mycelium; performing a second centrifugation after mixing the mycelium with water; and performing a third centrifugation on the supernatant obtained from the second centrifugation.
3. The method according to claim 2, characterized in that The first centrifugation time is 0.5 to 1.5 hours, and the rotation speed is 8000 to 12000 rpm; the second centrifugation time is 5.0 to 6.0 hours, and the rotation speed is 6000 to 10000 rpm; the third centrifugation time is 0.5 to 1.5 hours, and the rotation speed is 8000 to 12000 rpm.
4. The method according to claim 1, characterized in that: The pH value of the L-lactic acid fermentation broth to be centrifuged is 7.0-7.
5.
5. The method according to claim 4, characterized in that The method for obtaining L-lactic acid fermentation broth having a pH value of 7.0 to 7.5 includes: Performing a first pH adjustment on the L-lactic acid fermentation broth to obtain a first adjusted broth having a pH value of 7.0 to 7.5; heating the first regulating liquid to obtain a heated liquid; The pH value of the heated liquid is adjusted for the second time.
6. The method according to claim 5, characterized in that The reagents used to adjust the pH include milk of lime.
7. The method according to claim 5, characterized in that The heating temperature is 55-65°C.