Method and device for resource utilization of evaporation concentrated mother liquor

Abstract

The present application relates to a kind of methods for evaporative concentration mother liquor resource, specifically a kind of sodium sulfate is extracted from organic matter, sodium sulfate / sodium chloride brine, and sodium sulfate is converted into acid-base and is used for production process process, comprising: the inorganic membrane device is passed into to the organic matter, sodium sulfate / sodium chloride brine;The inorganic membrane device is passed into to refrigeration crystallization device, and ten sodium sulfate is obtained;After ten sodium sulfate is dissolved, it is passed into bipolar membrane device electrolysis, and sodium sulfate solution and sodium hydroxide solution are obtained.The present application can extract sodium sulfate from organic matter, sodium sulfate / sodium chloride brine, and sodium sulfate is converted into acid-base.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for evaporative concentration of mother liquor resource, belonging to the technical field of high organic matter concentrated brine resource utilization. BACKGROUND

[0002] In the bio-fermentation industry, fermentation process is the core step for producing various biological products (such as enzymes, antibiotics, organic acids, amino acids, etc.), and the subsequent processing steps are crucial for the purity and final yield of the products. After fermentation, the fermentation broth contains the target product as well as a large amount of unutilized nutrients, microbial cells, metabolic products and soluble impurities. In order to extract and purify the target product, a series of complex downstream processing techniques are usually adopted, among which product concentration and crystallization is an indispensable step.

[0003] The product concentration and crystallization process mainly removes water from the fermentation broth through evaporation, osmotic pressure adjustment or membrane separation, so that the target product reaches a supersaturated state and then crystallizes. However, a large amount of concentrated mother liquor is produced in this process, which has greatly reduced water content but is still rich in various complex components, mainly including high-concentration proteins, incomplete separation of cell debris, residual nutrients and a large amount of inorganic salts (such as sodium chloride, sodium sulfate, etc.).

[0004] The presence of these components poses great challenges to the treatment of concentrated mother liquor. First, high-concentration proteins not only occupy a large amount of resources, but also may cause problems such as pipeline blockage and equipment corrosion, affecting the smooth progress of subsequent processing. Second, the presence of cell debris and other organic impurities increases the difficulty and cost of wastewater treatment, as they are difficult to be effectively removed in traditional wastewater treatment processes.

[0005] Therefore, how to efficiently, economically and environmentally treat these fermentation concentrated mother liquor has become a technical problem to be solved in the bio-fermentation industry. For the treatment of evaporated concentrated mother liquor, early evaporation pond natural evaporation was widely used to achieve near-zero emission. However, the evaporation pond process not only occupies a large amount of land, but also produces solid salt which is classified as hazardous waste, with high disposal cost. In the field of hazardous waste treatment, the concentrated mother liquor after evaporation is currently mainly treated by incineration in the incineration system. However, the incineration system cannot handle a large amount of concentrated liquid, and it brings a lot of load to the downstream disposal system.

[0006] Currently, researchers are actively exploring various methods, such as resource utilization (such as extracting valuable bioactive substances, preparing fertilizers or feed additives), deep treatment (such as advanced oxidation, membrane separation technology for further purification) and reuse technology (such as being reused in the fermentation process after appropriate treatment), in order to maximize the utilization of resources and minimize the discharge of waste, and to promote the green upgrading and sustainable development of the bio-fermentation industry. SUMMARY

[0007] In view of the above problems, there is an urgent need to develop a high-efficiency and low-cost technology for resource utilization of salt in evaporated concentrated mother liquor, to solve the problem of hazardous waste disposal and recover economically valuable inorganic salt, thereby reducing the operating cost of zero emission.

[0008] The present application provides a method for processing evaporated concentrated mother liquor for resource utilization, which can effectively remove solid impurities and the like in the evaporated concentrated mother liquor, obtain sodium sulfate inorganic salt resources in the mixed salt solution, and also realize electrolysis of sodium sulfate inorganic salt into sodium hydroxide and sulfuric acid for use in the front-end process, thereby realizing resource utilization of sodium sulfate in the evaporated concentrated mother liquor. The solid impurities are removed by inorganic membrane treatment, the evaporated concentrated mother liquor is preliminarily purified, and then enters a freezing crystallization system for crystallization, the crystallized sodium sulfate decahydrate is dissolved, and then subjected to bipolar membrane electrolysis to obtain sodium hydroxide and sulfuric acid, which are returned to the front-end process, thereby realizing resource utilization of the evaporated concentrated mother liquor.

[0009] A method for resource utilization of evaporated concentrated mother liquor, comprising the following steps:

[0010] Step 1, the wastewater in the fermentation process is evaporated and concentrated, and then subjected to ceramic membrane filtration treatment;

[0011] Step 2, the permeate of the ceramic membrane is subjected to quality-based crystallization to precipitate sodium sulfate;

[0012] Step 3, after the sodium sulfate is redissolved, it is subjected to bipolar membrane electrolysis treatment to obtain sulfuric acid and sodium hydroxide;

[0013] The wastewater in the fermentation process contains sodium sulfate, sodium chloride and protein.

[0014] The wastewater in the fermentation process is the mother liquor after fermentation and crystallization; the water quality contains NaCl 10-60g / L, Mg 2+ 0.01-0.5g / L, Ca 2+ 0.01-0.5g / L, COD 1000-20000mg / L, Na2SO420-120g / L, and protein 20-200mg / L.

[0015] The average pore size of the ceramic membrane is 0.002μm~1μm, or the molecular weight cut-off is 10000~5000000Da.

[0016] The operating pressure range of the ceramic membrane is 0.05-0.5Mpa, and the cross-flow filtration is adopted with a flow rate of 1-10m / s.

[0017] During the filtration process of the ceramic membrane, a filter aid is added to the feed, and the addition amount is 0.5-5%.

[0018] The filter aid is one of diatomite, perlite, cellulose, asbestos, graphite powder, sawdust, magnesium oxide, gypsum, activated carbon, and acid clay.

[0019] The irreversible fouling in the ceramic membrane filtration process is calculated by the following formula:

[0020] R%=a*F 2 -β* F-γ*Ln(H+δ) / (1+ε*P) +ζ;

[0021] F refers to the backflushing frequency, P refers to the filter aid concentration, H refers to the calcium and magnesium ion concentration, and a / β / γ / δ / ε / ζ are parameters.

[0022] The irreversible fouling refers to the percentage decrease of the original flux after the pure water cross-flow washing for 30-90 min; the irreversible fouling is determined under the following filtration conditions: the total concentration of calcium and magnesium ions is 0.01-0.20 g / L, the mass ratio of calcium to magnesium is 3-8:1, the filter aid addition amount is 0.2-5%, the backflushing frequency is 10-50 min, the continuous filtration time is 100-300 min, the backflushing pressure is 0.5-1.5 Mpa, the backflushing time is 5-20 s, the filtration pressure is 0.2-0.4 Mpa, and the cross-flow flow rate is 2-5 m / s.

[0023] The temperature control for the fractional crystallization is -10℃-10℃, and more preferably 0-2℃.

[0024] The operating voltage for the bipolar membrane electrolysis treatment is 1-200 V, the current is 1-250 A, the feed pressure is 0.02-0.2 Mpa, and the membrane material of the bipolar membrane is selected from one or a combination of PVC, PEEK, PES, PET, PVDF, etc.

[0025] An evaporation and concentration mother liquor resource utilization device, comprising:

[0026] A concentration device for concentrating fermentation wastewater;

[0027] A ceramic membrane connected to the concentration device for filtering the concentrated liquid obtained in the concentration device;

[0028] A crystallizer connected to the permeation side of the ceramic membrane for fractional crystallization of the permeate of the ceramic membrane to precipitate sodium sulfate;

[0029] A solid-liquid separation device connected to the crystallizer for separating out the precipitated sodium sulfate;

[0030] A dissolving tank connected to the solid-liquid separation device for redissolving the sodium sulfate;

[0031] The bipolar membrane is connected to the dissolving tank and is used for bipolar membrane electrodialysis of the sodium sulfate solution obtained by redissolving to obtain sulfuric acid and sodium hydroxide.

[0032] The acid liquid tank and the alkali liquid tank are further included and are connected to the bipolar membrane respectively to receive the obtained sulfuric acid and sodium hydroxide.

[0033] The filter aid adding tank is further included and is connected to the feed side of the ceramic membrane to add filter aid into the ceramic membrane feed.

[0034] The solid-liquid separation equipment is a centrifuge.

[0035] The concentrated side of the ceramic membrane and / or the filtrate side of the solid-liquid separation equipment is connected to a spray dryer to respectively spray dry the concentrated liquid and the filtrate.

[0036] The ceramic membrane is a single-tube, flat-plate or multi-channel ceramic membrane.

[0037] The average pore size of the ceramic membrane is 0.002-1 μm or the molecular weight cut-off is 10,000-5,000,000 Da.

[0038] The material of the ceramic membrane is alumina, zirconia, silicon carbide or titanium oxide.

[0039] The bipolar membrane is a three-compartment bipolar membrane electrodialyzer or a two-compartment bipolar membrane electrodialyzer.

[0040] The diaphragm material of the bipolar membrane is selected from one of PVC, PEEK, PES, PET or PVDF. Advantages

[0041] The evaporation and concentration mother liquor resource utilization method can effectively solve the problem of resource utilization of mixed salt concentrated brine with high concentration of organic pollutants. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is the process flow chart of the application.

[0043] Figure 2 is the device diagram of the application.

[0044] Figure 3 is the ceramic membrane flux attenuation curve

[0045] Figure 4 is the correlation of the theoretical value and the actual value of the modeling sample

[0046] Figure 5 is the correlation of the theoretical value and the actual value of the verification sample

[0047] 1, concentration device; 2, ceramic membrane; 3, crystallizer; 4, solid-liquid separation device; 5, dissolving tank; 6, bipolar membrane; 7, acid tank; 8, alkali tank; 9, spray dryer; 10, filter aid feeding tank. DETAILED DESCRIPTION

[0048] The present application relates to a method for resource utilization of evaporation concentrated mother liquor, specifically, through inorganic membrane method to remove solid impurities, to realize the preliminary purification of evaporation concentrated mother liquor, and then into the freezing crystallization system for crystallization, and the crystallization of sodium sulfate ten water is dissolved, and then electrolyzed by bipolar membrane to produce sodium hydroxide and sulfuric acid, and then used in the front-end process, and finally realize the resource utilization method of evaporation concentrated mother liquor. It can solve the problem of hazardous waste disposal and recycle the inorganic salt with economic value, so as to reduce the operation cost of zero emission.

[0049] Approximations are used herein throughout the specification and claims, which can permit variations to occur when referring to any quantity, which can occur in the art, without changing the intended function of the quantity. Accordingly, the value of a term modified by a term such as "about" does not limit the exact value to the designated precise value. In at least some instances, the approximations can correspond to the precision of an instrument for measuring the value. Unless otherwise indicated, the limits of a range can be combined and / or interchanged, and such ranges are identified as encompassing all sub-ranges within the identified ranges. All numbers or expressions, including numerical and fractional values, throughout the specification and claims, are understood to be modified in all instances by the term "about" unless otherwise indicated. Numerical parameters include all averages unless otherwise indicated.

[0050] "Removing" in the present specification includes not only the case of completely removing the target substance, but also the case of partially removing (reducing the amount of the substance). "Purifying" in the present specification includes removing any or specific impurities.

[0051] The words "comprise", "comprising", "include", "including", "have", "has", "contain", "containing", or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. It will be understood that when an element is referred to as being "connected" to or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements can be present. The percentages described in the present application are mass percentages unless otherwise specified.

[0052] In the evaporation concentrated mother liquor that can be treated, the following examples 1-4 are treated with the waste brine produced after the fermentation liquid in the biological medicine fermentation industry is concentrated and crystallized.

[0053] In the fermentation process, microorganisms will use the substrate for metabolic activity, producing various metabolites, including water, carbon dioxide, organic acids, alcohols, etc. Among them, some metabolites may exist in the form of salt, such as lactic acid produced in the lactic acid fermentation process can combine with sodium ions to form sodium lactate, thereby increasing the salinity of the fermentation broth. In order to ensure the smooth progress of the fermentation process, it is necessary to control certain fermentation conditions, such as temperature, pH, dissolved oxygen, etc. In some cases, in order to adjust these conditions, a certain amount of salt (such as sodium chloride, sodium sulfate, etc.) may be added to the fermentation broth, which will remain in the fermentation broth after fermentation and form waste brine. The raw materials used in fermentation may contain a certain amount of salt, which will gradually dissolve in the fermentation broth during fermentation and form waste brine. After fermentation, the fermentation broth needs to be separated, purified, etc. to obtain the final product. In this process, a certain amount of wastewater may be produced, which contains waste brine produced during fermentation. If these waste waters are directly discharged into the environment, not only will it cause resource waste, but it may also pollute the environment.

[0054] The wastewater obtained after evaporation and concentration, which mainly contains sodium chloride and sodium sulfate, and contains protein, the main components in the evaporation and concentration mother liquor are NaCl 10-60g / L, Mg 2+ 0.01-0.5g / L, Ca 2+ 0.01-0.5g / L, COD 1000-20000mg / L, Na2SO420-120g / L, protein 20-200mg / L. The salt concentration can be determined by ICP method, COD is determined by method, and protein content is determined by coomassie method.

[0055] The concentrated mother liquor here is first filtered through a ceramic membrane device, which removes most of the protein, cell debris and suspended solids in the concentrated mother liquor. The ceramic membrane used here has an average pore size of 0.002μm~1μm, or a molecular weight cut-off of 10000~5000000Da, and an operating pressure range of 0.05-0.5Mpa. The filtration is carried out at a cross-flow velocity of 1-10m / s.

[0056] Since the protein content in the evaporation concentrated mother liquor is higher than that in the fermentation liquor, and protein is the main cause of irreversible pollution of ceramic membrane (protein is easy to form a gel layer on the surface of the membrane, and is difficult to remove by backwashing), in the present application, by adding filter aid (such as diatomite, perlite, cellulose, asbestos, graphite powder, sawdust, magnesium oxide, gypsum, activated carbon, acid clay) in the evaporation concentrated mother liquor, a filter cake layer is formed on the surface of the ceramic membrane by the filter aid, which can effectively prevent the gelation of protein on the surface of the ceramic membrane. The concentration of the filter aid added in the solution can be controlled at 0.5-5%. After the addition of the filter aid, the inhibition of irreversible pollution of the membrane during backwashing, the present application is based on the following assumptions to construct a model for irreversible pollution: if the backwashing frequency is too high, the filter cake layer formed on the surface is unstable, and if the backwashing frequency is too low, gelation gradually occurs; the concentration of calcium and magnesium ions in the feed liquid also promotes the generation of protein gelation; too high concentration of protein makes irreversible pollution more likely to occur; after the addition of a certain amount of filter aid, the membrane layer can be protected and irreversible pollution can be inhibited; on this basis, a prediction method for irreversible pollution of ceramic membrane in the process of ceramic membrane filtration of concentrated mother liquor containing filter aid is constructed. The following prediction equation is used: R%=α*F 2 -β* F-γ*Ln(H+δ) / (1+ε*P) +ζ. Wherein, F refers to the backwashing frequency (min), P refers to the filter aid concentration (%), H refers to the calcium and magnesium ion concentration (g / L), and α / β / γ / δ / ε / ζ are parameters. The irreversible pollution in the present application refers to the percentage decrease in the original flux after 30-90min of pure water cross-flow flushing after the filtration is completed.

[0057] After ceramic membrane filtration, the permeate of the ceramic membrane is sent to a freeze crystallization device to obtain mirabilite. The operation conditions of the freeze crystallization device can refer to the existing technology. The process of separating sodium sulfate and sodium chloride in the mixed salt solution and making sodium sulfate crystallize is mainly based on the difference in solubility of the two salts under different conditions and the common ion effect in the solution. The solubility of sodium chloride (NaCl) increases with the increase of temperature, but the increase is not large, that is, the solubility of sodium chloride is relatively small. The solubility of sodium sulfate (Na2SO4) increases with the increase of temperature when the temperature is less than 40 degrees Celsius, but when the temperature is greater than 40 degrees Celsius, the solubility decreases with the increase of temperature. This characteristic makes the solubility of sodium sulfate decrease at high temperature, so it is easier to precipitate from the solution. In the mixed salt solution, when the ion concentration of one salt increases, the dissolution of other salts with the same ion will be inhibited. In the mixed solution of sodium chloride and sodium sulfate, with the increase of the concentration of sodium chloride, the concentration of chloride ions and sodium ions in the solution increases, which will inhibit the dissolution of sodium sulfate to some extent, so that it is easier to precipitate in the form of crystals. By heating the mixed salt solution, the water in the solution can be evaporated, thereby increasing the concentration of the solution. Because the solubility of sodium sulfate decreases at high temperature, during the heating process, sodium sulfate is more likely to reach a supersaturated state and precipitate crystals. The solubility of sodium sulfate decreases at high temperature, while the solubility of sodium chloride changes little. This difference in solubility makes it easier for sodium sulfate to precipitate from the solution than sodium chloride during the heating process. In the actual crystallization process, the crystallization process can be optimized by controlling the evaporation temperature, evaporation rate, stirring intensity and other parameters to make the crystallization of sodium sulfate more sufficient and pure. For example, when using MVR evaporator for evaporation crystallization, micro-negative pressure operation and continuous crystallizer system can be used to realize the separation of sodium sulfate and sodium chloride, thereby further improving the purity and yield of the product. The temperature control of the freeze crystallization device is -10℃~10℃, and more preferably 0~2℃.

[0058] The dissolved sodium sulfate decahydrate enters the bipolar membrane electrolysis device to obtain sodium hydroxide and sulfuric acid. The preferred operating parameters of the bipolar membrane device electrolysis are: the operating voltage is 1-200V, the current is 1-250A, and the feeding pressure is 0.02-0.2MPa. The membrane material is selected from one or a combination of PVC, PEEK, PES, PET, PVDF, etc.

[0059] The concentrated solution obtained in the ceramic membrane filtration process or the mother liquor obtained in the crystallization of sodium sulfate can be subjected to spray drying treatment as solid waste treatment.

[0060] Based on the above process, the device structure provided by the application is as follows Figure 2 , comprising:

[0061] A concentration device 1 is used for concentrating the fermentation wastewater.

[0062] A ceramic membrane 2 is connected to the concentration device 1, and is used to filter the concentrated solution obtained in the concentration device 1;

[0063] A crystallizer 3 is connected to the permeate side of the ceramic membrane 2, and is used to perform quality separation crystallization on the permeate of the ceramic membrane 2, so as to precipitate sodium sulfate;

[0064] A solid-liquid separation device 4 is connected to the crystallizer 3, and is used to separate out the precipitated sodium sulfate;

[0065] A dissolving tank 5 is connected to the solid-liquid separation device 4, and is used to redissolve the sodium sulfate;

[0066] A bipolar membrane 6 is connected to the dissolving tank 5, and is used to perform bipolar membrane electrodialysis on the redissolved sodium sulfate solution, so as to obtain sulfuric acid and sodium hydroxide.

[0067] Further comprising: an acid solution tank 7 and an alkali solution tank 8, which are respectively connected to the bipolar membrane 6, and are used to receive the obtained sulfuric acid and sodium hydroxide.

[0068] Further comprising: a filter aid feeding tank 10, which is connected to the feed side of the ceramic membrane 2, and is used to add filter aid to the feed of the ceramic membrane.

[0069] The solid-liquid separation device 4 is a centrifuge.

[0070] The concentration side of the ceramic membrane 2 and / or the filtrate side of the solid-liquid separation device 4 is connected to a spray dryer 9, which is used to perform spray drying on the concentrated solution and the filtrate respectively.

[0071] The ceramic membrane 2 is a single-tube, flat-plate or multi-channel ceramic membrane.

[0072] The average pore size of the ceramic membrane 2 is 0.002 μm to 1 μm, or the molecular weight cut-off is 10,000 to 5,000,000 Da.

[0073] The material of the ceramic membrane 2 is alumina, zirconia, silicon carbide or titania.

[0074] The bipolar membrane 6 is a three-compartment bipolar membrane electrodialyzer or a two-compartment bipolar membrane electrodialyzer.

[0075] The diaphragm material of the bipolar membrane 6 is selected from one of PVC, PEEK, PES, PET or PVDF. Example 1

[0076] After extraction, the polylactic acid fermentation solution is evaporated and concentrated, and the mother liquor contains NaCl 40 g / L, Mg 2+ 0.01 g / L, Ca 2+0.05 g / L, COD 10600 mg / L, Na2SO4 96 g / L, protein 92 mg / L, the filtrate was obtained by filtering through a 200 nm ceramic membrane device at an operating pressure of 0.3 MPa and a cross-flow velocity of 3 m / s, and the solid matters such as protein were removed, and the ceramic membrane permeate was obtained. The ceramic membrane permeate was sent to a refrigeration crystallization device, and the sodium sulfate decahydrate crystals were obtained at a freezing temperature of 1 ℃. The sodium sulfate decahydrate crystals were dissolved and sent to a bipolar membrane system, and H2SO4 and NaOH were generated at an operating voltage of 100 V and an operating current density of 600.0 A / m 2 , and the acid current efficiency was 77.2%, and the base current efficiency was 81.4%. The mother liquor separated by sodium sulfate crystallization and the ceramic membrane concentrate were sent to a spray drying treatment as solid waste.

[0077] As a comparison, 2 wt% diatomite filter aid was added to the feed liquid before entering the ceramic membrane, and the flux attenuation curve of the first 20 min is shown in Figure 3 It can be seen that the filter cake layer can be formed on the surface of the membrane by adding filter aid in the feed liquid in the process of removing protein by filtering the mother liquor, so as to avoid the pollution of the membrane. Example 2

[0078] After the threonine fermentation liquid was extracted, the mother liquor was concentrated by evaporation, and contained NaCl 35 g / L, Mg 2+ 0.02 g / L, Ca 2+ 0.06 g / L, COD 11300 mg / L, Na2SO4 92 g / L, protein 87 mg / L, the filtrate was obtained by filtering through a 100 nm silicon carbide membrane device at an operating pressure of 0.3 MPa and a cross-flow velocity of 3 m / s, and the solid matters such as protein were removed, and the silicon carbide membrane permeate was obtained. The ion content in the silicon carbide membrane permeate was: Mg 2+ content 0.01 mg / L, Ca 2+ content 0.05 mg / L, COD 5800 mg / L, sodium sulfate 96 g / L, sodium chloride 40 g / L. The ceramic membrane permeate was sent to a refrigeration crystallization device, and the sodium sulfate decahydrate crystals were obtained at a freezing temperature of 2 ℃. The sodium sulfate decahydrate crystals were dissolved and sent to a bipolar membrane system, and H2SO4 and NaOH were generated at an operating voltage of 100 V and an operating current density of 400.0 A / m 2 , and the acid current efficiency was 71.2%, and the base current efficiency was 71.4%. The mother liquor separated by sodium sulfate crystallization and the ceramic membrane concentrate were sent to a spray drying treatment as solid waste. Example 3

[0079] After the glutathione fermentation liquid was extracted, the mother liquor was concentrated by evaporation, and contained NaCl 45 g / L, Mg 2+ 0.02 g / L, Ca 2+0.07 g / L, COD 12180 mg / L, Na2SO4 86 g / L, protein 63 mg / L, filtration through a 50 nm ceramic membrane device at an operating pressure of 0.3 MPa and a cross-flow velocity of 3 m / s, so that the protein and other solid substances are removed, and the ion content in the ceramic membrane permeate is: Mg 2+ 0.01 mg / L, Ca 2+ 0.05 mg / L, COD 5500 mg / L, Na2SO4 96 g / L, NaCl 40 g / L. The ceramic membrane permeate is sent to a freeze crystallization device, the freezing temperature is controlled at 0°C, and sodium sulfate ten-water crystals are obtained. After the sodium sulfate ten-water crystals are dissolved, they are sent to a bipolar membrane system, the operating voltage is 100 V, and the operating current density is 1000.0 A / m 2 2, H2SO4 and NaOH are generated, the acid current efficiency is 87.2%, and the base current efficiency is 91.4%. The mother liquor of sodium sulfate crystallization separation and the ceramic membrane concentrated liquid are sent to a spray drying treatment as solid waste. Example 4

[0080] The ceramic membrane is periodically backwashed, taking the ceramic membrane clarification of the concentrated liquid of the polylactic acid fermentation wastewater in Example 1 as an example.

[0081] After the polylactic acid fermentation liquid is extracted, the evaporation concentrated mother liquor contains NaCl 40 g / L, Mg 2+ and Ca 2+ (total concentration is artificially adjusted to 0.01, 0.02, 0.05 g / L, 0.10 g / L, 0.15 g / L, and 0.20 g / L according to the mutual ratio of 5:1 by weight), COD 10600 mg / L, Na2SO4 96 g / L, protein 92 mg / L, diatomite filter aid (0.2%, 0.5%, 1%, 2%, 3%, and 5%) is added to the feed liquid, filtration through a 200 nm ceramic membrane device at an operating pressure of 0.3 MPa and a cross-flow velocity of 3 m / s, so that the protein and other solid substances are removed, backwashing pressure is 1.0 MPa, backwashing time is 10 s each time, backwashing frequency is set to 10 min, 20 min, 30 min, 40 min, and 50 min, and the ceramic membrane permeate is obtained. After a total time of 180 min, after pure water cross-flow flushing for 50 min, the pure water flux is re-determined, and the irreversible pollution proportion value is calculated.

[0082] According to the assumption idea, the following prediction equation is used: R%=α*F 2 -β* F-γ*Ln(H+δ) / (1+ε*P) +ζ.

[0083] Wherein, F refers to the backwashing frequency (min), P refers to the filter aid concentration (%), H refers to the calcium and magnesium ion concentration (g / L), and α / β / γ / δ / ε / ζ are parameters.

[0084] The prediction equation for the 10 modeling samples is:

[0085] R%=0.06*F 2 -3.53* F-5.94*Ln(H+0.12) / (1+0.12*P) +72.03 The correlation of the theoretical and actual values of the modeling samples is shown in Figure 4 , with an average error of 10.5%; the correlation of the theoretical and actual values of the 5 verification samples is shown in Figure 5 , with an average error of 13.5%.

Claims

1. A method for the resource utilization of concentrated evaporation liquor, characterized in that, Includes the following steps: Step 1: Evaporate and concentrate the wastewater from the fermentation process, and then filter it through a ceramic membrane. Step 2: The permeate from the ceramic membrane undergoes fractional crystallization, causing sodium sulfate to precipitate. Step 3: After redissolving sodium sulfate, sulfuric acid and sodium hydroxide are obtained by bipolar membrane electrolysis. The wastewater from the fermentation process contains sodium sulfate, sodium chloride, and protein. The wastewater from the fermentation process is the mother liquor after fermentation crystallization; the water contains NaCl: 10-60 g / L, Mg... 2+ 0.01-0.5 g / L, Ca 2+ : 0.01-0.5g / L, COD: 1000-20000mg / L, Na2SO4: 20-120g / L, protein: 20-200mg / L; The ceramic membrane has an average pore size of 0.002 μm to 1 μm, or a molecular weight cutoff of 10,000 to 5,000,000 Da; the operating pressure range of the ceramic membrane is 0.05-0.5 MPa, and cross-flow filtration is used with a flow rate of 1-10 m / s. During the filtration process of the ceramic membrane, a filter aid is added to the feed at a rate of 0.5-5%. The filter aid is one of the following: diatomaceous earth, perlite, cellulose, asbestos, graphite powder, sawdust, magnesium oxide, gypsum, activated carbon, and acidic clay. Irreversible fouling in ceramic membrane filtration is predicted and calculated using the following formula: Irreversible fouling as a percentage R = 0.06 × F 2 -3.53× F-5.94×Ln(H+0.12) / (1+0.12×P) +72.03; F refers to the backwash frequency in min, P refers to the filter aid concentration in %, and H refers to the calcium and magnesium ion concentration in g / L; the irreversible contamination refers to the percentage decrease in flux compared to the original flux after filtration and cross-flow rinsing with pure water for 30-90 min. Irreversible contamination was determined under the following filtration conditions: total calcium and magnesium ion concentration of 0.01-0.20 g / L, calcium-magnesium mass ratio of 3-8:1, filter aid dosage of 0.2-5%, backwash frequency of 10-50 min, continuous filtration time of 100-300 min, backwash pressure of 0.5-1.5 MPa, backwash time of 5-20 s, filtration pressure of 0.2-0.4 MPa, and cross-flow velocity of 2-5 m / s.

2. The method for resource utilization of evaporation and concentration mother liquor according to claim 1, characterized in that, The temperature control for fractional crystallization is -10℃ to 10℃; the operating voltage for bipolar membrane electrolysis is 1~200V, the current is 1~250A, the feed pressure is 0.02~0.2Mpa, and the membrane material of the bipolar membrane is selected from one or a combination of several of PVC, PEEK, PES, PET, and PVDF.

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