阅读说明：本技术 分离乳酸盐的方法和系统 (Method and system for separating lactate ) 是由 佟毅 李义 郭元亨 陈博 陶进 杨凯 于 2020-05-25 设计创作，主要内容包括：本发明涉及乳酸盐的分离纯化领域,公开了一种分离乳酸盐的方法和系统,该方法包括：(1)将乳酸盐发酵液与助滤剂混合、固液分离,得到第一料液和滤饼；(2)将所述滤饼进行气顶水洗处理,得到第二料液；(3)将所述第一料液和第二料液进行浓缩处理,得到乳酸盐；其中,所述乳酸盐选自乳酸铵和/或乳酸钠。本发明采用气顶水洗处理,大幅降低乳酸盐发酵液在菌体分离过程中乳酸盐的损失量,提高了乳酸盐的收率。此外,该方法和系统,简单实用,不需要增加设备投资和试剂耗费,同时降低操作难度,降低乳酸生产过程中和单位成本。(The invention relates to the field of separation and purification of lactate and discloses a method and a system for separating lactate, wherein the method comprises the following steps: (1) mixing lactate fermentation liquor with a filter aid, and carrying out solid-liquid separation to obtain a first feed liquid and a filter cake; (2) carrying out gas cap washing treatment on the filter cake to obtain a second feed liquid; (3) concentrating the first feed liquid and the second feed liquid to obtain lactate; wherein the lactate is selected from ammonium lactate and/or sodium lactate. The method adopts the gas cap washing treatment, greatly reduces the loss of the lactate in the lactate fermentation liquor in the thallus separation process, and improves the yield of the lactate. In addition, the method and the system are simple and practical, do not need to increase equipment investment and reagent consumption, and simultaneously reduce the operation difficulty and the unit cost in the lactic acid production process.)

1. A method of separating lactate salt, the method comprising:

(1) mixing lactate fermentation liquor and filter aid in sequence, and performing solid-liquid separation to obtain first feed liquid and a filter cake;

(2) carrying out gas cap washing treatment on the filter cake to obtain a second feed liquid;

(3) carrying out downstream treatment on the mixed solution of the first feed liquid and the second feed liquid to obtain lactate;

wherein the lactate is selected from ammonium lactate and/or sodium lactate.

2. The process according to claim 1, wherein the lactate fermentation broth is obtained by fermentation using a lactic acid fermenting species selected from at least one of lactococcus lactis, lactobacillus, bacillus and rhizopus, preferably lactobacillus;

preferably, the lactobacillus is selected from at least one of lactobacillus rhamnosus, lactobacillus plantarum and pediococcus acidilactici, preferably lactobacillus rhamnosus;

preferably, the lactate fermentation broth has a lactate content of 50-300 g/mL.

3. The process according to claim 1 or 2, wherein the solid to liquid ratio of the filter aid to the lactate fermentation broth is (0.1-10): 100g/L, preferably (0.5-5): 100g/L, more preferably (0.5-3): 100 g/L;

preferably, the filter aid is selected from at least one of diatomaceous earth, activated carbon and perlite.

4. A process according to any one of claims 1 to 3, wherein the mixing is carried out in a manner selected from paddle stirring and/or frame stirring, preferably frame stirring;

preferably, the mixing conditions include: the temperature is 0 to 40 ℃, more preferably 10 to 30 ℃, still more preferably 15 to 25 ℃, and the rotation speed is 10 to 100rpm, still more preferably 30 to 80rpm, still more preferably 40 to 60 rpm.

5. The process according to any one of claims 1 to 4, wherein the solid-liquid separation is filtration, which is carried out in a plate and frame filter;

preferably, the pressure of the filtration is 0.05 to 0.5MPa, more preferably 0.1 to 0.4MPa, and still more preferably 0.15 to 0.25 MPa.

6. The method of any one of claims 1-5, wherein the gas cap water wash treatment process comprises: and sequentially carrying out first top blowing, water washing and second top blowing on the filter cake.

7. The method of claim 6, wherein the first top-blowing is a first top-blowing of the filter cake with compressed air to produce a lactate permeate;

preferably, the water washing is to soak the filter cake subjected to the first top blowing with water to obtain a lactate residual solution;

preferably, the second top blowing is to perform second top blowing on the filter cake subjected to water washing by using compressed air to obtain a water washing solution;

preferably, the second feed solution comprises the lactate permeate, the lactate retentate, and a water wash.

8. The method according to claim 7, wherein the pressure of the compressed air is 0.05-0.3MPa, preferably 0.1-0.3MPa, more preferably 0.12-0.2 MPa;

preferably, the time of the water washing is 10-120min, more preferably 30-90min, and still more preferably 40-80 min.

9. A system for separating lactate, the system comprising: the filter unit, the gas cap washing unit and the downstream processing unit are sequentially communicated;

the filtering unit comprises a mixing tank with a stirring device, a liquid booster pump, a plate-and-frame filter and a filtrate receiving tank;

the gas cap water washing unit comprises an air compressor, a compressed air storage tank, a water storage tank and a water delivery pump.

10. The system of claim 9, wherein the filter cloth in the plate and frame filter is an acid-resistant filter cloth;

preferably, the mesh number of the filter cloth is 200-.

Technical Field

The invention relates to the field of separation and purification of lactate, in particular to a method and a system for separating lactate.

Background

In recent years, the research on the generation of biodegradable materials is active, and the application of the biodegradable materials relates to the fields of food packaging, agricultural films, medical materials and the like, and particularly the research on the medical biodegradable materials is the most hot point. Among the various biodegradable materials, Polylactate (PLA) has a number of outstanding advantages: for example, the biodegradable polymer has good biocompatibility, low toxicity and cheap raw materials, and can participate in the metabolism of human bodies, so that the biodegradable polymer can be used as a substitute for polyvinyl chloride (PVC), polypropylene (PP) and other packaging materials produced by petroleum raw materials. In addition, PLA also has similar glossiness and processing performance to polystyrene, and can be widely applied to the fields of drug slow-release materials, human tissue materials, fracture fixation materials, water treatment film materials and the like. Based on the above performance characteristics, PLA is considered as the most promising biodegradable material.

The optical activity of the synthesized poly-lactate monomer can be classified into the following types: l-lactate, D-lactate, meso-lactide, D-lactide, L-lactide, with which polymers can be synthesized: levorotatory Polylactate (PLLA), dextrorotatory Polylactate (PDLA), racemic Polylactate (PDLLA), optically inactive polylactate (Meso-PLA). When PDLLA is used as a biodegradable material in the in-vivo environment of a human body, the shrinkage rate reaches over 50 percent, and the application of PDLLA is limited. PLLA and PDLA have more excellent mechanical properties and application prospects, in addition, a human body only contains enzyme capable of metabolizing L-lactate, D-lactate cannot be absorbed by the human body, and the world health organization advocates that the L-lactate is used as a food additive and an oral medicine material to replace DL-lactate which is generally used at present. The preparation of lactate generally comprises: obtaining a mixture of L-and D-forms having a composition of 50/50 via the petrochemical route; the lactate salt may be obtained in its entirely L-form by biological fermentation (i.e., by biological fermentation) or may be prepared by chemical synthesis. At present, the production of L-lactate worldwide is exclusively carried out by microbial fermentation, except in Japan.

The first step of lactate preparation by all microbial fermentations is the solid-liquid separation between the somatic cells and the fermentation broth. Solid-liquid separation in industrial production is generally performed by filtration or disc centrifugation. During the centrifugation, the heavy phase also has to be kept in a flowing state, and the liquid holdup is also high, so that a considerable part of lactate is lost along with the heavy phase; in the filtering process, the problem that the filtering speed is reduced due to the accumulation of thalli on the surface of the filter cloth is unavoidable, and in this case, precoating filter cakes are difficult to avoid because thalli cells are accumulated on the surface of the precoating layer. On the other hand, a large amount of lactate is contained in the liquid between the bacterial cells and inside the bacterial cells, and this lactate is often lost with the discarding of the bacterial cells, resulting in a low lactate yield and a serious waste.

Therefore, a need exists for a method and system for separating lactate.

Disclosure of Invention

The invention aims to provide a method and a system for separating lactate, which aim to solve the problems of serious lactate waste and low lactate yield in the existing method for separating thalli cells and lactate in the process of separating the thalli cells of lactate fermentation liquor. The method can effectively avoid the loss of lactate, improve the yield of the lactate and further reduce the production cost.

In order to achieve the above object, a first aspect of the present invention provides a method for separating a lactate salt, the method comprising:

(1) mixing lactate fermentation liquor and filter aid in sequence, and performing solid-liquid separation to obtain first feed liquid and a filter cake;

(2) carrying out gas cap washing treatment on the filter cake to obtain a second feed liquid;

(3) carrying out downstream treatment on the mixed solution of the first feed liquid and the second feed liquid to obtain lactate;

wherein the lactate is selected from ammonium lactate and/or sodium lactate.

Preferably, the lactate fermentation broth has a lactate content of 50-300 g/mL.

Preferably, the process of the gas cap water washing treatment comprises the following steps: and sequentially carrying out first top blowing, water washing and second top blowing on the filter cake.

A second aspect of the invention provides a system for separating lactate, the system comprising: the filter unit, the gas cap washing unit and the downstream processing unit are sequentially communicated;

the filtering unit comprises a mixing tank with a stirring device, a liquid booster pump, a plate-and-frame filter and a filtrate receiving tank;

the gas cap water washing unit comprises an air compressor, a compressed air storage tank, a water storage tank and a water delivery pump.

Compared with the prior art, the invention has the following advantages:

(1) the method adopts the gas cap washing treatment, greatly reduces the loss of the lactate in the solid-liquid separation process of the lactate fermentation liquor, and improves the yield of the lactate;

(2) the system for separating the lactate provided by the invention is simple and practical, does not need to increase equipment investment and reagent consumption, and simultaneously reduces the operation difficulty and unit cost in the lactate production process;

(3) compared with the prior art, the yield of the lactate is more than or equal to 90 percent.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In a first aspect the present invention provides a method for separating lactate salt, the method comprising:

(1) mixing lactate fermentation liquor and filter aid in sequence, and performing solid-liquid separation to obtain first feed liquid and a filter cake;

(2) carrying out gas cap washing treatment on the filter cake to obtain a second feed liquid;

(3) carrying out downstream treatment on the mixed solution of the first feed liquid and the second feed liquid to obtain lactate;

wherein the lactate is selected from ammonium lactate and/or sodium lactate.

In the present invention, there is a wide range of choices for the lactate fermentation broth, as long as the lactate content of the lactate fermentation broth is between 50 and 300 g/mL. Preferably, the lactate fermentation broth is obtained by fermentation using a lactic acid fermenting species, wherein the lactic acid fermenting species is selected from at least one of lactococcus lactis, lactobacillus, bacillus and rhizopus, preferably lactobacillus.

Preferably, the lactobacillus is selected from at least one of lactobacillus rhamnosus, lactobacillus plantarum and pediococcus acidilactici, preferably lactobacillus rhamnosus.

According to a preferred embodiment of the invention, the lactate fermentation broth is a fermentation broth of lactobacillus rhamnosus, and the content of lactate is 50-300g/mL, wherein the lactobacillus rhamnosus is CGMCC No.16834(CN 109628339A).

In the present invention, in order to promote solid-liquid separation of bacterial cells in the lactate fermentation broth, the lactate fermentation broth is mixed with a filter aid, preferably, the filter aid is at least one selected from diatomaceous earth, activated carbon and perlite, preferably perlite.

According to the present invention, preferably, the solid-to-liquid ratio of the filter aid to the lactate fermentation broth is (0.1-10): 100g/L, wherein the solid-to-liquid ratio refers to the dosage of the filter aid relative to 100L of lactate fermentation liquor, and the dosage of the filter aid is 0.1-10 g. For example, the solid to liquid ratio may be 0.1: 100g/L, 0.3: 100g/L, 0.5: 100g/L, 1: 100g/L, 2: 100g/L, 3: 100g/L, 4: 100g/L, 5: 100g/L, 6: 100g/L, 8: 100g/L, 10: 100g/L and any intermediate value therebetween, more preferably (0.5 to 5): 100g/L, more preferably (0.5-3): 100 g/L. The preferable solid-liquid ratio is adopted, so that the loss amount of the lactate in the solid-liquid separation process of the somatic cells in the lactate fermentation liquor can be reduced, and the yield of the lactate in the separation process can be improved.

In the present invention, the mixing method may be widely selected as long as the lactate fermentation broth and the filter aid are uniformly mixed. Preferably, the mixing is performed by a method selected from paddle stirring and/or frame stirring, and more preferably frame stirring.

Preferably, the mixing conditions include: the temperature is 0 to 40 ℃, more preferably 10 to 30 ℃, still more preferably 15 to 25 ℃, and the rotation speed is 10 to 100rpm, still more preferably 30 to 80rpm, still more preferably 40 to 60 rpm. The loss amount of the lactate in the solid-liquid separation process of the somatic cells in the lactate fermentation liquor can be effectively reduced by adopting the optimized mixing condition.

According to the present invention, the solid-liquid separation is preferably filtration, and in the present invention, the filtration method may be selected from a wide range, and the mixture of the lactate fermentation broth and the filter aid may be subjected to solid-liquid separation to obtain the first feed liquid and the filter cake. In order to avoid the loss of lactate in the mixture of lactate fermentation broth and filter aid in the separation of the bacteria, the filtration is preferably carried out in a plate and frame filter.

According to a preferred embodiment of the invention, the filtration is carried out with stirring, i.e. the stirring is not interrupted during the filtration. By adopting the filtering mode, the dissolution of the lactate in the thallus of the lactate fermentation liquor can be effectively promoted, thereby reducing the loss of the lactate.

Preferably, the filtration pressure is 0.05 to 0.5MPa, for example, 0.05MPa, 0.1MPa, 0.15MPa, 0.2MPa, 0.25MPa, 0.3MPa, 0.35MPa, 0.4MPa, 0.45MPa, 0.5MPa, and any intermediate value therebetween, more preferably 0.1 to 0.4MPa, and still more preferably 0.15 to 0.25 MPa.

According to the present invention, preferably, the gas cap water washing treatment process comprises: sequentially carrying out first top blowing, water washing and second top blowing on the filter cake, wherein the first top blowing is to carry out first top blowing on the filter cake by using compressed air to obtain lactate permeate; the water washing is to soak the filter cake subjected to the first top blowing with water to obtain lactate residual solution; and performing second top blowing on the washed filter cake by using compressed air to obtain a washing liquid.

In the present invention, the second feed liquid includes the lactate permeate, the lactate residual solution, and a water wash solution, unless otherwise specified; the lactate permeate is permeate of lactate in a filter cake blown out by using compressed air through a first top blowing, the lactate residual solution is residual solution of lactate in thallus cells washed out by using water after the first top blowing is finished, and the water washing solution is aqueous solution of lactate in the filter cake blown out by using compressed air through a second top blowing after the water washing is finished.

In the invention, the filter cake obtained by filtering the lactate fermentation liquor is subjected to gas cap water washing treatment, so that the problems that the filtration rate is reduced due to the fact that thalli are accumulated on the surface of filter cloth and lactate is remained in liquid among thalli cells and in the liquid are solved, and the lactate yield is low due to the fact that the lactate is lost along with the abandonment of the thalli cells in the filtering process.

According to the invention, preferably, the pressure of the compressed gas is between 0.05 and 0.3MPa, preferably between 0.1 and 0.3MPa, more preferably between 0.12 and 0.2 MPa.

Preferably, the time of the water washing is 10-120min, more preferably 30-90min, and still more preferably 40-80 min.

In the present invention, the downstream processing means, unless otherwise specified, concentrating a mixed solution of the first feed liquid and the second feed liquid, and specifically means: the cation and anion are removed by ion exchange, and then the water is removed by molecular distillation, wherein the ion exchange and the molecular distillation are conventional technical means in the field, and the invention is not limited to the method.

In the present invention, the yield of lactate obtained by the above separation method is not less than 90%, preferably not less than 94%.

A second aspect of the invention provides a system for separating lactate, the system comprising: the filter unit, the gas cap washing unit and the downstream processing unit are sequentially communicated;

the filtering unit comprises a mixing tank with a stirring device, a liquid booster pump, a plate-and-frame filter and a filtrate receiving tank;

the gas cap water washing unit comprises an air compressor, a compressed air storage tank, a water storage tank and a water delivery pump.

According to the invention, preferably, the filter cloth in the plate-and-frame filter is an acid-resistant filter cloth, further preferably, the mesh number of the filter cloth is 200-.

In the invention, the gas cap water washing unit is adopted to effectively avoid slow reduction of the filtration rate caused by accumulation of filter cakes on the filter cloth in the filtering process of the lactate fermentation liquor, and simultaneously, liquid among thallus cells in the filter cakes and lactate remained in thallus are also avoided, thereby reducing the yield of the lactate.

The present invention will be described in detail below by way of examples.

The plate-and-frame filter is purchased from Hainin Yunfei filtration equipment Co., Ltd, and has a model of YF-100-1.

The mobile air compressor was purchased from Shanghai Xizai compressor, Inc. and was W1.5/20 in model number.

The liquid booster pump was purchased from Tenglong Pump valve manufacturing, Anhui, under the model number CQB 32-25-125F.

A lactate detection method, which adopts a high performance liquid chromatography detection method; the method comprises the following steps: chromatograph: agilent technologies 1260Infinity II; a detector: RID; separating the column: aminex HPX-87H Column 300X 7.8 mm; mobile phase: 0.005M sulfuric acid; flow rate: 0.5 mL/min; sample introduction amount: 20 mu L of the solution; the retention time of lactate is 10-20 min.

The lactic acid fermentation strain is Lactobacillus rhamnosus, CGMCC No.16834(CN 109628339A).