CN216614472U - Refining treatment system of xylitol fermentation liquid - Google Patents

Abstract

The utility model relates to a refining treatment system of xylitol fermentation liquor, which comprises a fermentation tank, a post-fermentation tank, a ceramic membrane filter, a nanofiltration membrane filter, an activated carbon filter, an ion exchange column, an evaporation tank, a crystallization tank, a centrifuge and a dryer, which are communicated through pipelines, wherein the post-fermentation tank is used for storing fermentation liquor obtained by the fermentation tank and standing to obtain supernatant fermentation liquor, the ceramic membrane filter, the nanofiltration membrane filter, the activated carbon filter and the ion exchange column are used for removing impurities from the supernatant fermentation liquor to obtain xylitol ion exchange liquid, the evaporation tank and the crystallization tank are used for carrying out evaporation crystallization treatment on the xylitol ion exchange liquid to obtain xylitol massecuite, the centrifuge is used for separating the xylitol massecuite to obtain crystal xylitol, and the dryer is used for drying the crystal xylitol to obtain xylitol crystals. The utility model obviously reduces the usage amount of the active carbon, can also improve the pH value of the feed liquid, obviously reduces the conductivity and reduces the load in the subsequent ion exchange process.

Description

Refining treatment system of xylitol fermentation liquid

Technical Field

The utility model belongs to the technical field of xylitol preparation, and particularly relates to a refining treatment system of xylitol fermentation liquor.

Background

Xylitol is a five-carbon sugar alcohol, is mostly prepared by chemically hydrogenating xylose in the current industrial production, and has some technical bottlenecks at present although the reaction conditions are mild in biological conversion. At present, xylitol is prepared by a biological method, biomass resources such as corncobs and straws are generally adopted as raw materials, and hemicellulose hydrolysate is obtained after acid hydrolysis. After acidolysis, the concentration of xylose in the hydrolysate is low, and the xylose cannot be directly used as a raw material for biological fermentation, so the raw hydrolysate needs to be concentrated, and the commonly adopted process is evaporation concentration. In this process, sugars, proteins and other substances in the raw material may undergo maillard reactions, which may result in a darkening of the color of the raw material liquid. The raw material prepared by the process is fermented, so that the color of the final fermentation liquor is very dark, and the subsequent refining process of the fermentation liquor is greatly hindered. The patent of publication No. CN108949839A describes a method for preparing high-purity xylitol, in which the fermentation broth is sterilized, decolorized, ion-exchanged, concentrated, crystallized and dried to obtain xylitol crystal product, however, the decolorization process adopts activated carbon for decolorization, the addition amount is 20%, which is nearly 100 times of the addition amount of chemical method, the industrial production cost is too high, and simultaneously a large amount of waste carbon is generated.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem of providing a refining treatment system of xylitol fermentation liquor, which can obviously reduce the usage amount of activated carbon, improve the pH value of feed liquid, obviously reduce the conductivity and reduce the load in the subsequent ion exchange process under the condition of ensuring the decoloring and light transmission.

The utility model is realized in such a way that a xylitol fermentation broth refining treatment system is provided, the system comprises a fermentation tank, a post-fermentation tank, a ceramic membrane filter, a nanofiltration membrane filter, an activated carbon filter and an ion exchange column which are sequentially communicated through a pipeline, the device comprises an evaporation tank, a crystallizing tank, a centrifugal machine and a dryer, wherein the tank after fermentation is used for storing xylitol fermentation liquor obtained by the fermentation tank and standing for layering treatment to respectively obtain precipitates and supernatant fermentation liquor, a ceramic membrane filter, a nanofiltration membrane filter, an activated carbon filter and an ion exchange column are sequentially used for filtering and removing impurities from the supernatant fermentation liquor to obtain xylitol ion exchange liquid, the evaporation tank and the crystallizing tank are used for carrying out evaporation crystallization treatment on the xylitol ion exchange liquid to obtain xylitol massecuite, the centrifugal machine is used for separating the xylitol massecuite to respectively obtain crystal xylitol and mother liquor, and the dryer is used for drying the crystal xylitol to obtain a refined xylitol crystal product.

Further, the ion exchange column includes an anion exchange column and a cation exchange column.

Compared with the prior art, the refining treatment system of the xylitol fermentation liquor has the following characteristics:

1. after the treatment of the process, the light transmission of the decoloring section can reach more than 90 percent.

2. The pH value of the treated material liquid can be improved, part of ions are adsorbed, the conductivity is obviously reduced, and the load in the subsequent ion exchange process is reduced.

3. The xylitol crystal product prepared by the primary crystallization meets the national standard requirements, and the crystal surface is regular and smooth and has high purity.

Drawings

FIG. 1 is a schematic diagram of a preferred embodiment of the xylitol fermentation broth refining system of the present invention;

FIG. 2 is a schematic flow diagram of a xylitol fermentation broth refining process system and method of the present invention;

FIG. 3 is an HPLC purity analysis chart of the xylitol crystal product prepared in example 1 of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and are not intended to limit the utility model.

Referring to fig. 1 and 2, the preferred embodiment of the refining treatment system for xylitol fermentation broth according to the present invention comprises a fermentation tank 1, a post-fermentation tank 2, a ceramic membrane filter 3, a nanofiltration membrane filter 4, an activated carbon filter 5, an ion exchange column 6, an evaporation tank 7, a crystallization tank 8, a centrifuge 9, and a dryer 10, which are sequentially connected through a pipeline. The arrows show the direction of flow of material in the system.

And the post-fermentation tank 2 is used for storing the xylitol fermentation liquor obtained by the fermentation tank 1 and standing for layering treatment to respectively obtain a precipitate and supernatant fermentation liquor A. The ceramic membrane filter 3, the nanofiltration membrane filter 4, the activated carbon filter 5 and the ion exchange column 6 are sequentially used for filtering and removing impurities from the supernatant fermentation liquor A to obtain xylitol ion exchange liquid, the evaporation tank 7 and the crystallization tank 8 are used for carrying out evaporation crystallization treatment on the xylitol ion exchange liquid to obtain xylitol massecuite, the centrifuge 9 is used for separating the xylitol massecuite to respectively obtain crystalline xylitol and mother liquor, and the dryer 10 is used for drying the crystalline xylitol to obtain a refined xylitol crystal B product.

The ion exchange column 6 includes a cation exchange column 61 and an anion exchange column 62.

Referring to fig. 1 and fig. 2, the present invention further provides a refining method of xylitol fermentation broth, which uses the refining system of xylitol fermentation broth, the method comprises the following steps:

taking biomass resources such as corncobs and the like as raw materials, removing impurities, rinsing and carrying out acidolysis treatment to obtain a fermentation raw material solution, concentrating the fermentation raw material solution until the concentration of xylose is more than 500g/L, and fermenting by adopting genetically engineered bacteria to obtain xylitol fermentation liquor A; and standing the xylitol fermentation liquor A to respectively obtain a precipitate and supernatant fermentation liquor. The solid content of the fermentation raw material liquid is 10-13%, the conductivity is 14000-16000 mu s/cm, and the pH is 6.0-6.8. The precipitate was further treated.

And step two, filtering the supernatant fermentation liquor by using a ceramic membrane to obtain ceramic membrane discharge liquid without thalli and large-particle impurities, wherein the process parameters of the step are that the feeding temperature is 36-48 ℃, and the filtering pressure is 0.2-0.4 MPa.

And step three, conveying the ceramic membrane discharge liquid into a nanofiltration filter for nanofiltration membrane filtration treatment, and intercepting impurity molecules with the molecular weight of more than 400Da to obtain nanofiltration liquid with the light transmittance of 20-40%, wherein the feeding temperature of the nanofiltration treatment is 36-48 ℃, and the filtration pressure is 2.5-3.3 MPa.

And step four, performing activated carbon filtration treatment on the obtained nanofiltration solution by using activated carbon, and then sequentially performing ion exchange treatment on the nanofiltration solution by using a cation exchange column 61 and an anion exchange column 62 to obtain xylitol ion exchange solution, wherein the usage amount of the activated carbon is 0.5-1.0%, and the conductivity of the ion exchange solution is less than 20 mus/cm.

And step five, evaporating and concentrating the xylitol ion-exchange liquid until the refraction is 78-82%, then cooling and crystallizing to obtain xylitol massecuite, centrifuging the massecuite to obtain crystal xylitol and mother liquor, and drying the crystal xylitol to obtain a refined xylitol crystal B product.

And step six, mixing the mother liquor and the xylitol ion-exchange liquid, concentrating the mixture, and recycling the concentrated mixture.

The present invention will be further described with reference to the following examples.

Example 1

The first embodiment of the refining treatment system for xylitol fermentation broth comprises the following steps:

step 11, preparation of xylitol fermentation liquor: taking biomass resources such as corncobs and the like as raw materials, and obtaining a fermentation raw material solution after impurity removal, rinsing and acidolysis. And further concentrating the fermentation raw material liquid after impurity removal, decoloration and other steps until the xylose concentration is more than 500 g/L. Then, obtaining xylitol fermentation liquor after fermentation by genetic engineering bacteria, wherein the solid content in the fermentation liquor accounts for 11%, the conductance value is 16000 mu s/cm, and the pH value is 6.2. Besides fermentation microorganisms, the fermentation liquor also contains impurities such as large particles of corn steep liquor, and the fermentation liquor is dark in color and has light transmittance of 0%.

And step 12, taking 6L of xylitol fermentation liquor, and carrying out ceramic membrane filtration treatment. The membrane module intercepts thalli and large-particle impurities with the particle size of more than 50nm, the average flux is 2L/h, the filtering pressure is 0.2MPa, the temperature of the feed liquid is 45 ℃, the conductivity value of the treated feed liquid is reduced to 13460ms/cm, and the pH value of the feed liquid is 6.4.

And step 13, filtering the ceramic membrane discharge liquid by a nanofiltration membrane for decoloring. The process adopts a nanofiltration membrane with the interception quantity of more than 400 Da. The treatment temperature is 45 ℃, the filtration pressure is 3.3MPa, and the flux is about 6L/h. After nanofiltration and decoloration, the light transmittance of the feed liquid is increased from 0 percent to 33 percent, the pH value is increased to 6.8, and the electric conductivity value is reduced to 7588 mu s/cm.

And step 14, after the treatment in the step (2), adding 0.5% of activated carbon powder into the system to carry out secondary decolorization treatment by activated carbon filtration. Conditions are as follows: decolorizing at 60 deg.C for 2 h. The secondary decoloration liquid is pH6.9, the electric conductivity value is reduced to 6865 mu s/cm, and the light transmission of the feed liquid is 92.4%.

And step 15, performing ion exchange treatment in the ion exchange process after the secondary decolored solution obtained by the treatment in the step 3, controlling the discharge conductance to be less than 50 mu s/cm in the ion exchange process, and improving the yield of the stage process by adopting a water top mode.

And step 16, evaporating and concentrating the ion exchange discharge liquid to refract light by 82%, carrying out subsequent cooling crystallization treatment process, and carrying out centrifugal drying treatment to obtain xylitol crystals.

The purity of the prepared xylitol crystal reaches 99.71 percent through HPLC (high performance liquid chromatography) measurement, the xylitol crystal is white in appearance, the crystal is in a prismatic shape through microscope observation, the crystal surface is regular and smooth, the condition that fine crystals are adsorbed on the surfaces of large particles is less, and other indexes all meet the national standard requirements. FIG. 3 is an HPLC purity analysis chart of xylitol crystal product.

Example 2 nanofiltration membrane test with different cut-offs

The nanofiltration membrane type selection test method in the decoloring process of the xylitol fermentation liquid comprises the following steps: nanofiltration membranes with the interception aperture of 200Da, 400Da and 600Da respectively are selected for carrying out a decolorization effect test, and comprehensive evaluation is carried out on the two aspects of the feed liquid decolorization effect and the subsequent addition amount of secondary decolorization activated carbon so as to select the nanofiltration membrane with the proper aperture.

(1) Respectively equally dividing 30L of ceramic membrane discharge liquid into three parts, each of which is 10L; the material liquid of the ceramic membrane discharging liquid has the light transmittance of 0 percent, and the pH value of the material liquid is about 6.47.

(2) 200Da cut-off quantity nanofiltration membrane decolorization test: 10L of feed liquid is added into nanofiltration equipment, the treatment pressure is 3.3MPa, the flux is about 4L/h, and the temperature of the feed liquid is 45 ℃. The light transmission of the feed liquid after nanofiltration treatment is about 48 percent. The process yield was < 50%. After the treatment of 200Da nanofiltration membrane, 0.5% of active carbon is added for treatment, the light transmittance of the feed liquid can be improved to 96%.

(3) 400Da cut-off volume nanofiltration membrane decolorization test: 10L of feed liquid is added into nanofiltration equipment, the treatment pressure is 3.3MPa, the flux is about 6L/h, and the temperature of the feed liquid is 45 ℃. The light transmission of the feed liquid after nanofiltration treatment is about 35 percent. The process yield was > 90%. After the treatment of the 400Da nanofiltration membrane, 0.5 percent of active carbon is added for treatment, and the light transmittance of the feed liquid can be improved to 92 percent.

(4) And (3) performing 600Da connection flow nanofiltration membrane decolorization test: 10L of feed liquid is added into nanofiltration equipment, the treatment pressure is 3.3MPa, the flux is about 6L/h, and the temperature of the feed liquid is 45 ℃. The light transmission of the feed liquid after nanofiltration treatment is about 17.06 percent. The process yield was > 90%. After the 600Da nanofiltration membrane treatment, about 2% of activated carbon is added for treatment, and the light transmittance of the feed liquid can be improved to more than 90%.

(5) Compared with the membrane decoloring effects of different cut-off amounts of 200Da, 400Da and 600Da, the method has the advantages that the decoloring effect and the subsequent addition amount of the activated carbon are integrated, the effect of the nanofiltration membrane cut-off with the aperture of 400Da is the best, the yield is high, and the secondary addition amount of the activated carbon is small.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the utility model, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (2)

1. A refining treatment system for xylitol fermentation liquor is characterized by comprising a fermentation tank, a ceramic membrane filter, a nanofiltration membrane filter, an activated carbon filter and an ion exchange column which are sequentially communicated through pipelines, the device comprises an evaporation tank, a crystallizing tank, a centrifugal machine and a dryer, wherein the tank after fermentation is used for storing xylitol fermentation liquor obtained by the fermentation tank and standing for layering treatment to respectively obtain precipitates and supernatant fermentation liquor, a ceramic membrane filter, a nanofiltration membrane filter, an activated carbon filter and an ion exchange column are sequentially used for filtering and removing impurities from the supernatant fermentation liquor to obtain xylitol ion exchange liquid, the evaporation tank and the crystallizing tank are used for carrying out evaporation crystallization treatment on the xylitol ion exchange liquid to obtain xylitol massecuite, the centrifugal machine is used for separating the xylitol massecuite to respectively obtain crystal xylitol and mother liquor, and the dryer is used for drying the crystal xylitol to obtain a refined xylitol crystal product.

2. The xylitol fermentation broth refining treatment system according to claim 1, wherein said ion exchange column comprises an anion exchange column and a cation exchange column.

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