A coupled treatment method for protein fraction recovery and deep purification of gluten meal wastewater

Abstract

This invention provides a coupled treatment method for the graded recovery and deep purification of protein in gluten wastewater, belonging to the field of wastewater resource treatment technology. It solves the technical problems of existing methods, such as the difficulty in simultaneously achieving high protein recovery rates and effective wastewater purification, and severe membrane fouling. The method includes the following steps: pretreatment, primary flocculation recovery, secondary flocculation purification, optional ultrasound-assisted alkaline extraction and acid precipitation enhancement, ultrafiltration deep treatment, and protein consolidation and drying. Through the synergistic coupling of primary flocculation with sodium alginate, secondary flocculation with Aspergillus tabineus, ultrasound-assisted alkaline extraction and acid precipitation enhancement, and ultrafiltration deep treatment, it achieves efficient graded recovery of protein and deep purification of wastewater. This invention achieves high protein recovery rates and can simultaneously and efficiently remove COD, total phosphorus, total nitrogen, and ammonia nitrogen from wastewater. The two-stage flocculation pretreatment effectively alleviates membrane fouling and extends membrane lifespan; the entire process uses biodegradable flocculants, making it environmentally friendly. The recovered protein has a balanced amino acid profile and high added value.

Description

Technical Field

[0001] This invention belongs to the field of wastewater resource utilization technology, and relates to a protein coupling treatment method for gluten wastewater, particularly a coupling treatment method for graded recovery and deep purification of protein in gluten wastewater. Background Technology

[0002] Wheat gluten, a high-value-added product from deep wheat processing, generates a large amount of high-concentration organic wastewater during its production. This wastewater is rich in soluble proteins, starch, pentosans, and pollutants such as chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN), and ammonia nitrogen (NH3-N). Direct discharge of this wastewater not only causes eutrophication and disrupts the aquatic ecological balance but also results in a serious waste of valuable protein resources.

[0003] Existing technologies for treating gluten wastewater and recovering protein have several limitations: the alkaline extraction and acid precipitation method is mature but has a low protein recovery rate, consumes a large amount of acid and alkali, and is prone to secondary pollution; while ultrafiltration alone can retain protein, membrane fouling is a prominent problem, resulting in high operating costs and complex maintenance; although natural organic polymeric flocculants (such as sodium alginate) can achieve high recovery rates, sodium alginate requires strong acid conditions, increasing the difficulty of subsequent wastewater treatment, and has limited effectiveness in removing pollutants such as total phosphorus; microbial flocculation is environmentally friendly, but when used alone, it is difficult to achieve both high recovery and high pollutant removal rates; while comprehensive methods can improve efficiency, the process combination lacks systematic optimization, and membrane fouling control and cost balance remain key challenges.

[0004] Therefore, we propose a coupled treatment technology with strong process synergy, high protein recovery rate, good wastewater purification effect, controllable membrane fouling, and environmental friendliness, which has important practical significance for the green and sustainable development of the gluten powder industry. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a coupled treatment method for protein fractionation and deep purification of gluten wastewater. The technical problem to be solved by this invention is: how to achieve efficient resource utilization and compliant discharge of gluten wastewater through coupled treatment technologies that have strong process synergy, high protein recovery rate, good wastewater purification effect, controllable membrane fouling, and are environmentally friendly.

[0006] The objective of this invention can be achieved through the following technical solutions: A coupled treatment method for protein fractionation and deep purification of gluten wastewater includes the following steps: Step 1. Pretreatment: Collect the wastewater from the production of wheat gluten powder, centrifuge it at a speed of 3000-5000 r / min for 10-15 min to remove insoluble impurities such as starch, and obtain a clear protein-containing wastewater stock solution; Step 2. Primary flocculation and recovery: Add natural organic polymer flocculant to the wastewater raw liquid obtained in Step 1, adjust the pH of the system to 2.5-3.5, control the flocculation temperature to 20-30℃, stir evenly, let stand for flocculation for 20-30 minutes, and separate the solid and liquid to obtain primary recovered protein and primary purified supernatant. The preferred natural organic polymeric flocculant is sodium alginate, with a dosage of 0.8-1.2 g / L. The sodium alginate is added by first preparing an aqueous solution with a mass fraction of 1-2%, and then adding it to the wastewater in proportion.

[0007] Step 3. Secondary flocculation and purification: Adjust the pH of the primary purification supernatant obtained in Step 2 to 8.0-9.5, add microbial flocculant, add calcium chloride as a coagulant aid at a concentration of 0.01-0.05%, stir at 120-150 r / min for 5-10 min, and let stand for 120-180 min for secondary flocculation. Solid-liquid separation yields secondary recovered protein and secondary purification supernatant. The microbial flocculant is a lyophilized powder reconstituted solution of Aspergillus tubingensis fermentation broth, with a dosage concentration of 15-25 mg / mL; Step 4. Ultrasonic-assisted alkaline extraction and acid precipitation enhancement: The supernatant obtained from the secondary purification in Step 3 is subjected to ultrasonic-assisted alkaline extraction and acid precipitation treatment: the pH is adjusted to 9.0-10.0, and the mixture is kept at 40-48℃ for 50-60 min for alkaline extraction; then the pH is adjusted to 5.5-6.5, and the mixture is kept at 30-35℃ for 15-25 min for acid precipitation. Ultrasonic assistance is introduced during the acid precipitation stage, with an ultrasonic power of 120-160W and an ultrasonic time of 6-8 min. Solid-liquid separation yields tertiary recovered protein and tertiary purified supernatant. Step 5. Ultrafiltration Deep Treatment: The supernatant obtained from the three-stage purification in Step 3 or Step 4 is sent to the ultrafiltration system for filtration. The ultrafiltration membrane has a molecular weight cutoff of 3000-10000 Da, the operating pressure is 0.2-1.1 MPa, and the operating temperature is 25-35℃. The ultrafiltration retentate (fourth-stage recovered protein) and the permeate (deeply purified wastewater) are collected. The ultrafiltration membrane is preferably a polyvinylidene fluoride (PVDF) hollow fiber membrane or a PES membrane. Before use, it should be rinsed with deionized water, 0.5 mol / L sodium hydroxide solution, and then deionized water in sequence to reduce membrane fouling. After ultrafiltration, the ultrafiltration membrane is cleaned online as follows: rinse with clean water for 10-15 min → alkaline wash with 0.5 mol / L sodium hydroxide solution for 20-30 min → rinse with clean water for 20-30 min → acid wash with 0.1-0.2 mol / L hydrochloric acid solution for 20-30 min → rinse with clean water until neutral.

[0008] Step 6. Protein Combining and Drying: Combine the recovered proteins obtained in Steps 2, 3, and 4 with the ultrafiltration residue obtained in Step 5, and freeze-dry or spray-dry to obtain high-purity protein powder.

[0009] Furthermore, the preparation method of the reconstituted solution of Aspergillus tabine lyophilized powder in step three is as follows: 3.1. Strain screening and purification: Activated sludge was taken from gluten wastewater, serially diluted and spread on PDA medium, and cultured at 28±1℃ for 3-5 days. The Aspergillus tabine strain was purified by the streak plate method. 3.2. Fermentation culture: The strain was inoculated into PDB liquid medium and cultured at 28±1℃ and 120-180 r / min for 5-7 days using a liquid-to-liquid culture method. 3.3. Preparation of freeze-dried powder: The fermentation broth was centrifuged at 8000 r / min for 20 min to remove the cells. The supernatant was pre-frozen at -40℃ for 6 h and then freeze-dried at a vacuum of 10-20 Pa and a cold trap temperature of -50℃ for 24 h to obtain freeze-dried powder. Before use, it was reconstituted with deionized water to the required concentration.

[0010] Compared with existing technologies, the coupled treatment method of protein fractionation and deep purification for gluten wastewater has the following advantages: This invention improves protein recovery rate, achieving efficient staged recovery; it also simultaneously and efficiently removes COD, total phosphorus, total nitrogen, and ammonia nitrogen from wastewater. Through two-stage flocculation pretreatment, it effectively mitigates membrane fouling, extends membrane lifespan, and reduces operating and maintenance costs.

[0011] This invention offers a flexible process, allowing for the selective activation of the ultrasonic enhancement unit; it uses biodegradable flocculants throughout the process, making it environmentally friendly. The recovered protein has a balanced amino acid profile, resulting in high added value. The equipment is highly compatible, suitable for low-cost retrofitting and large-scale application in enterprises of different sizes. Attached Figure Description

[0012] Figure 1 This is a process flow diagram of the present invention.

[0013] Figure 2 This is a graph showing the changes in protein content in wastewater at different treatment stages in this invention.

[0014] Figure 3 This is a comparison chart of protein recovery rates using different processing methods in this invention.

[0015] Figure 4 This is a comparison chart of the removal effects of COD, TP, TN and NH3-N in wastewater at different treatment stages in this invention. Detailed Implementation

[0016] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0017] like Figure 1 As shown, the coupled treatment method for protein fractionation and deep purification of gluten wastewater includes the following steps: Step 1. Pretreatment: Collect the wastewater from the production of wheat gluten powder, centrifuge it at a speed of 3000-5000 r / min for 10-15 min to remove insoluble impurities such as starch, and obtain a clear protein-containing wastewater stock solution; Step 2. Primary flocculation and recovery: Add natural organic polymer flocculant to the wastewater raw liquid obtained in Step 1, adjust the pH of the system to 2.5-3.5, control the flocculation temperature to 20-30℃, stir evenly, let stand for flocculation for 20-30 minutes, and separate the solid and liquid to obtain primary recovered protein and primary purified supernatant. The preferred natural organic polymeric flocculant is sodium alginate, with a dosage of 0.8-1.2 g / L and an optimal dosage of 1.0 g / L. The optimal conditions for primary flocculation recovery are: pH 3.0, sodium alginate dosage 1.0 g / L, and flocculation temperature 25℃; The preferred method for adding sodium alginate is to first prepare an aqueous solution with a mass fraction of 1-2%, and then add it to the wastewater according to the proportion. Step 3. Secondary flocculation and purification: Adjust the pH of the primary purification supernatant obtained in Step 2 to 8.0-9.5, add microbial flocculant, and add calcium chloride as a coagulant aid (concentration of 0.01-0.05%). Stir at 120-150 r / min for 5-10 min, and let stand for 120-180 min for secondary flocculation. Solid-liquid separation is performed to obtain secondary recovered protein and secondary purification supernatant. The microbial flocculant is a lyophilized powder reconstituted solution of Aspergillus tabine fermentation broth, with a dosage concentration of 15-25 mg / mL and an optimal concentration of 20 mg / mL. The optimal conditions for secondary flocculation purification are: pH 9.0, lyophilized powder reconstitution solution concentration 20 mg / mL, and standing time 150 min. Step 4. Ultrasonic-assisted alkaline extraction and acid precipitation enhancement: The supernatant obtained from the secondary purification in Step 3 is subjected to ultrasonic-assisted alkaline extraction and acid precipitation treatment: the pH is adjusted to 9.0-10.0, and the mixture is kept at 40-48℃ for 50-60 min for alkaline extraction; then the pH is adjusted to 5.5-6.5, and the mixture is kept at 30-35℃ for 15-25 min for acid precipitation. Ultrasonic assistance is introduced during the acid precipitation stage, with an ultrasonic power of 120-160W and an ultrasonic time of 6-8 min. Solid-liquid separation yields tertiary recovered protein and tertiary purified supernatant. The optimal conditions for ultrasound-assisted alkali extraction and acid precipitation are as follows: alkali extraction pH 9.6, temperature 45℃, time 55 min; acid precipitation pH 6.0, temperature 30℃, time 20 min; ultrasound power 140W, ultrasound time 7 min. Step 5. Ultrafiltration Deep Treatment: The supernatant obtained from the three-stage purification in Step 3 or Step 4 is sent to the ultrafiltration system for filtration. The ultrafiltration membrane has a molecular weight cutoff of 3000-10000 Da, the operating pressure is 0.2-1.1 MPa, and the operating temperature is 25-35℃. The ultrafiltration retentate (fourth-stage recovered protein) and the permeate (deeply purified wastewater) are collected. The ultrafiltration membrane is preferably a polyvinylidene fluoride (PVDF) hollow fiber membrane or a PES membrane. Before use, it should be rinsed with deionized water, 0.5 mol / L sodium hydroxide solution, and then deionized water in sequence to reduce membrane fouling. After ultrafiltration, the ultrafiltration membrane is cleaned online as follows: rinse with clean water for 10-15 min → alkaline wash with 0.5 mol / L sodium hydroxide solution for 20-30 min → rinse with clean water for 20-30 min → acid wash with 0.1-0.2 mol / L hydrochloric acid solution for 20-30 min → rinse with clean water until neutral. Step 6. Protein Combining and Drying: Combine the recovered proteins obtained in Steps 2, 3, and 4 with the ultrafiltration residue obtained in Step 5, and freeze-dry or spray-dry to obtain high-purity protein powder.

[0018] Furthermore, the preparation method of the reconstituted solution of Aspergillus tabine lyophilized powder in step three is as follows: 3.1. Strain screening and purification: Activated sludge was taken from gluten wastewater, serially diluted and spread on PDA medium, and cultured at 28±1℃ for 3-5 days. The Aspergillus tabine strain was purified by the streak plate method. 3.2. Fermentation culture: The strain was inoculated into PDB liquid medium and cultured at 28±1℃ and 120-180 r / min for 5-7 days using a liquid-to-liquid culture method. 3.3. Preparation of freeze-dried powder: The fermentation broth was centrifuged at 8000 r / min for 20 min to remove the cells. The supernatant was pre-frozen at -40℃ for 6 h and then freeze-dried at a vacuum of 10-20 Pa and a cold trap temperature of -50℃ for 24 h to obtain freeze-dried powder. Before use, it was reconstituted with deionized water to the required concentration.

[0019] In summary, 1. High protein recovery rate and controllable fractionation: Through a fractional recovery system of "two-stage flocculation + optional ultrasound-assisted alkaline extraction and acid precipitation + ultrafiltration", the total protein recovery rate can reach over 93%, of which the primary flocculation recovery rate of sodium alginate is as high as (99.29±0.36)%, and the secondary flocculation recovery rate of microbial flocculation is (47.26±2.11)%. The recovery rate is further improved by combining ultrasound assistance and ultrafiltration, which is superior to single treatment methods.

[0020] 2. Wastewater purification effect: The coupled process can achieve a removal rate of over 90% for COD, TP, and TN, with the highest removal rate of COD reaching 96.95%, TP reaching 95.25%, TN reaching 98.30%, and NH3-N reaching 70.07-80.83%. The effluent quality meets the requirements for deep purification and effectively solves the problem of low removal rates of ammonia nitrogen and total phosphorus by single flocculants.

[0021] 3. Effective control of membrane fouling: Through two-stage flocculation pretreatment, more than 90% of the protein and some colloidal substances in the wastewater are removed first, reducing the membrane fouling rate in the subsequent ultrafiltration process. The membrane flux decay rate is reduced to below 18.2%, extending the membrane service life by more than 30% and reducing operation and maintenance costs.

[0022] 4. Flexible and environmentally friendly process: The ultrasonic-assisted alkaline extraction and acid precipitation unit can be flexibly selected based on the actual wastewater quality, treatment scale and cost budget; the entire process uses biodegradable natural polymer flocculants and microbial flocculants, avoiding the secondary pollution risks that may be caused by synthetic organic polymer flocculants, and the amount of chemical agents used is small, which is in line with the concept of green circular economy development.

[0023] 5. High degree of resource utilization and strong adaptability: The recovered protein has a balanced amino acid composition, with essential amino acids retained intact at a content of 77.41-106.12 mg / g. Some amino acid contents are higher than those of the raw material gluten, resulting in higher added value for feed or food use. The process parameters are clearly defined, and the equipment requirements are highly compatible with the wastewater treatment systems of existing gluten production enterprises. It can achieve industrial applications of different scales through modular design, making it suitable for low-cost transformation of small and medium-sized enterprises as well as meeting the large-scale treatment needs of large enterprises. Example 1: Complete Coupled Process for Treating Gluten Wastewater Step 1. Pretreatment: Take the gluten production wastewater from a biotechnology company in Lai'an County, Chuzhou City, Anhui Province, centrifuge at 4000 r / min for 10 min to remove starch residue, and obtain the supernatant (original wastewater solution). Its water quality indicators are: soluble protein 1950±575 mg / L, COD 29833±527 mg / L, TP 952±205 mg / L, TN 4885±4.44 mg / L, NH3-N 69.36±0.48 mg / L, pH 4.07.

[0024] Step 2. Primary Flocculation Recovery: Take 1L of raw wastewater, adjust the pH to 3.0 with dilute hydrochloric acid, add 1.0g / L sodium alginate solution (prepare a 1% aqueous solution first, then add proportionally), stir rapidly at 300r / min for 2min, then stir slowly at 100r / min for 10min, let stand at 25℃ for 30min, and centrifuge at 4000r / min for 10min to obtain primary recovered protein and primary purification supernatant. Test results: The primary protein recovery rate was 99.29%. The primary purification supernatant, relative to the raw wastewater, showed COD removal rates of 86.28%, TP removal rates of 2.31%, TN removal rates of 53.45%, and NH3-N removal rates of 26.09%. Changes in wastewater protein content at different treatment stages are shown below. Figure 2 As shown.

[0025] Step 3. Secondary Flocculation and Purification: Adjust the pH of the primary purification supernatant to 9.0 with sodium hydroxide, add 0.01% calcium chloride solution and a 20 mg / mL reconstituted solution of Aspergillus tabine lyophilized powder (final concentration 20 mg / mL), stir at 120 rpm for 5 min, let stand at 28℃ for 150 min, and centrifuge at 4000 rpm for 10 min to obtain the secondary recovered protein and the secondary purification supernatant. Detection results: The secondary protein recovery rate was 47.26%, and the COD removal rate, TP removal rate, TN removal rate, and NH3-N removal rate of the secondary purification supernatant were 65.68%, 6.20%, 20.35%, and 11.64%, respectively.

[0026] Step 4. Ultrasonic-assisted alkaline extraction and acid precipitation enhancement: Adjust the pH of the secondary purification supernatant to 9.6, incubate at 45℃ for 55 min, and centrifuge to collect the supernatant; adjust the pH to 6.0, incubate at 30℃ for 20 min, and during the acid precipitation stage, turn on the ultrasound (140W, 7 min), centrifuge at 4000 r / min for 10 min to obtain the tertiary recovered protein and the tertiary purification supernatant. Detection results: The tertiary protein recovery rate was 53.83%, and the COD removal rate, TP removal rate, TN removal rate, and NH3-N removal rate of the tertiary purification supernatant were 67.09%, 22.99%, 20.66%, and 19.86%, respectively.

[0027] Step 5. Ultrafiltration Deep Treatment: The supernatant from the three-stage purification process is fed into the ultrafiltration system. The ultrafiltration membrane is a PES membrane (molecular weight cutoff 3000 Da). The operating pressure is 0.5 MPa, the operating temperature is 30℃, and the system is run for 1 hour. The ultrafiltration retentate and permeate are collected. After ultrafiltration, online cleaning is performed according to the prescribed procedure. Test results: The recovery rate of the ultrafiltration retentate (fourth-stage protein recovery) is 85.84%, and the permeate removal rates are 96.95%, 95.25%, 98.30%, and 80.83%. A comparison of the removal effects of COD, TP, TN, and NH3-N in wastewater at different treatment stages is shown in the figure. Figure 4 As shown.

[0028] Step 6. Protein consolidation and drying: The primary, secondary, and tertiary recovered proteins and ultrafiltration residues are combined and freeze-dried to obtain protein powder. The content of essential amino acids is 106.12 mg / g, and the content of some amino acids is higher than that of the raw material gluten powder. Example 2: Simplified Coupled Process for Treating Gluten Wastewater (Omitting Ultrasonic-Assisted Alkali Extraction and Acid Precipitation Steps) Step 1. Preprocessing: Same as in Example 1.

[0029] Step 2. Primary flocculation recovery: Same as in Example 1.

[0030] Step 3. Secondary flocculation purification: Same as in Example 1.

[0031] Step 4. Ultrafiltration Deep Treatment: The supernatant from the secondary purification was directly fed into the ultrafiltration system, with operating conditions the same as in Example 1. Test Results: The total protein recovery rate was 93.22%, the permeate COD removal rate was 92.35%, TP removal rate was 93.66%, TN removal rate was 95.45%, and NH3-N removal rate was 70.07%. After 72 hours of continuous operation, the membrane flux decay rate was 18.2%. Under the same operating conditions, the flux decay rate of the directly ultrafiltered raw wastewater was 56.7%, significantly lower than that of the directly ultrafiltered raw wastewater. Comparative example of single alkali extraction and acid precipitation method for treating gluten wastewater The same batch of raw wastewater was treated using a traditional alkaline extraction and acid precipitation method under the following conditions: alkaline extraction at pH 9.6, temperature 45℃, and time 55 min; acid precipitation at pH 6.0, temperature 30℃, and time 20 min. The test results showed that the protein recovery rate was 37.94%, COD removal rate was 67.09%, TP removal rate was 22.99%, TN removal rate was 20.66%, and NH3-N removal rate was 19.86%. All these indicators were lower than those of the coupled process of this invention.

[0032] A comparison chart of protein recovery rates using different processing methods, as shown below. Figure 3 As shown.

[0033] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A coupled treatment method for protein fraction recovery and deep purification of gluten meal wastewater, characterized in that, Includes the following steps: Step 1. Pretreatment: The wastewater from the production of wheat gluten is centrifuged to remove insoluble starch and suspended solids, resulting in the original wastewater solution. Step 2. Primary flocculation and recovery: Sodium alginate is added to the raw wastewater as a flocculant, and flocculation and precipitation are carried out under the conditions of pH 2.5-3.5 and temperature 20-30℃ to separate the primary recovered protein and the primary purified supernatant. Step 3. Secondary flocculation and purification: Add a reconstituted solution of Aspergillus tabine fermentation broth as a microbial flocculant to the supernatant of the primary purification, adjust the pH to 8.0-9.5, add calcium chloride as a coagulant aid, stir and let stand for 120-180 min, and separate the secondary recovered protein and the secondary purification supernatant. Step 4. Ultrasonic-assisted alkaline extraction and acid precipitation enhancement: The supernatant from the secondary purification is subjected to ultrasonic-assisted alkaline extraction and acid precipitation treatment: the pH is adjusted to 9.0-10.0, and the mixture is kept at 40-48℃ for 50-60 minutes for alkaline extraction; then the pH is adjusted to 5.5-6.5, and the mixture is kept at 30-35℃ for 15-25 minutes for acid precipitation. Ultrasonic assistance is introduced during the acid precipitation stage, with an ultrasonic power of 120-160W and an ultrasonic time of 6-8 minutes. Solid-liquid separation yields tertiary recovered protein and tertiary purified supernatant. Step 5. Ultrafiltration Deep Treatment: The supernatant from the three purification processes is subjected to ultrafiltration. The ultrafiltration membrane has a molecular weight cutoff of 3000-10000 Da. The ultrafiltration residue and permeate are collected. Step 6. Protein consolidation and drying: Combine the primary, secondary, and tertiary recovered proteins and ultrafiltration residues, and dry them to obtain protein powder.

2. The coupled treatment method for protein fractionation and deep purification of gluten wastewater according to claim 1, characterized in that, In step two, the dosage of sodium alginate is 0.8-1.2 g / L. The sodium alginate is added by first preparing an aqueous solution with a mass fraction of 1-2%, and then adding it to the wastewater according to the proportion.

3. The coupled treatment method for protein fractionation and deep purification of gluten wastewater according to claim 1, characterized in that, In step three, the concentration of the microbial flocculant is 15-25 mg / mL; the concentration of the coagulant calcium chloride is 0.01-0.05%.

4. The coupled treatment method for protein fractionation and deep purification of gluten wastewater according to claim 1, characterized in that, The preparation method of the reconstituted solution of Aspergillus tabineis lyophilized powder in step three is as follows: the Aspergillus tabineis strain is obtained by screening and purifying from gluten wastewater, and after liquid-to-liquid fermentation culture, the supernatant is collected by centrifugation and freeze-dried. Before use, it is reconstituted with deionized water to the required concentration.

5. The coupled treatment method for protein fractionation and deep purification of gluten wastewater according to claim 1, characterized in that, In step four, the ultrafiltration membrane is a polyvinylidene fluoride hollow fiber membrane or a PES membrane, with an operating pressure of 0.2-1.1 MPa and an operating temperature of 25-35℃. After ultrafiltration, the membrane module is cleaned online, and the cleaning steps include rinsing with clean water, alkaline washing, acid washing, and rinsing with clean water again.

6. The coupled treatment method for protein fractionation and deep purification of gluten wastewater according to claim 1, characterized in that, In step one, the centrifugation speed is 3000-5000 r / min and the time is 10-15 min.

7. The coupled treatment method for protein fractionation and deep purification of gluten wastewater according to claim 1, characterized in that, The drying process in step five is either freeze-drying or spray drying.

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