System and method for co-producing single-cell protein through electrodialysis treatment of organic wastewater and hydrogen oxidizing bacteria fermentation

Abstract

The invention provides a system and a method for co-producing single-cell protein through electrodialysis treatment of organic wastewater and hydrogen oxidizing bacteria fermentation, the system and the method are divided into an anode chamber, a middle chamber and a cathode chamber through a cation exchange membrane and an anion exchange membrane, and the anode chamber and the cathode chamber are filled with organic wastewater; and the middle chamber is filled with a hydrogen oxidizing bacteria fermentation culture medium. Under the driving of an electric field, ammonium ions and acetate ions in the wastewater are selectively migrated to the middle chamber through the anion and cation exchange membrane respectively, and are efficiently utilized by hydrogen oxidizing bacteria as a nitrogen source and a carbon source to produce single-cell protein. According to the system, collaborative integration of an electrodialysis technology and a microbial fermentation process is successfully realized, nutrient substances in the organic wastewater are recovered and converted into single-cell protein with high additional value while the organic wastewater is purified, the treatment burden is effectively converted into protein resources, and the system has environmental benefits, economical efficiency and sustainability.

Description

Technical Field

[0001] This invention belongs to the field of single-cell protein production technology, and relates to a system and method for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria. Background Technology

[0002] Single-cell protein (SCP) is a cytoplasmic mass rich in various nutrients such as protein, vitamins, fats, and carbohydrates. SCP has high nutritional value, containing all eight essential amino acids required by the human body, with a protein content of 40-80%. It can serve as a novel alternative protein in the feed industry, alleviating the protein demand problem caused by population growth, reducing CO2 emissions, and contributing to sustainable development. Hydrogen-Oxidizing bacteria (HOB) are facultative chemoautotrophic organisms, typical bacteria that produce SCP, and possess carbon fixation capabilities.

[0003] With rising economic levels and increasing urban populations, the generation of organic waste continues to increase, with a surge in the discharge of organic wastewater containing high concentrations of ammonia nitrogen and acetic acid. Traditional biological treatment processes often face technical bottlenecks such as carbon-to-nitrogen ratio imbalance and inhibition of microbial activity. Electrodialysis (ED) is an electrochemical separation process that uses electric current to transport charged ions through ion exchange membranes, selectively recovering nutrients from organic wastewater while using anion and cation exchange membranes to block other pollutants. ED has many advantages, including energy saving, low sludge production, and simple pretreatment, thus showing broad application prospects in material recovery and wastewater treatment.

[0004] At present, there is no research or literature on the recovery of acetic acid and ammonia nitrogen from organic wastewater (such as biogas slurry) by ED, and then the in-situ production of SCP by HOB. Summary of the Invention

[0005] Based on the above objectives, the present invention provides a system and method for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxyl bacteria.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, this application provides a system for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria. The system includes an anode chamber, an intermediate chamber, and a cathode chamber separated by a cation exchange membrane and an anion exchange membrane. Both the anode chamber and the cathode chamber are filled with organic wastewater. The intermediate chamber contains HOB fermentation medium and hydroxide bacteria.

[0007] In this application, organic wastewater refers to wastewater rich in organic acids and ammonia nitrogen, including but not limited to food processing wastewater, aquaculture wastewater, chemical production wastewater, and biogas slurry or simulated biogas slurry produced from the fermentation of organic solid waste. The raw materials for preparing simulated biogas slurry include CH3COONa, NH4Cl, and HOB fermentation medium.

[0008] Specifically, based on the concentrations in the HOB fermentation medium, the concentrations of CH3COONa and NH4Cl are 0.30-10.00 g / L and 0.30-6.00 g / L, respectively. For example, based on the concentration in HOB fermentation medium, the concentration of CH3COONa can be 0.30 g / L, 0.80 g / L, 1.00 g / L, 2.00 g / L, 3.00 g / L, 4.00 g / L, 5.00 g / L, 6.00 g / L, 7.00 g / L, 8.00 g / L, 9.00 g / L, 10.00 g / L, or any concentration between two of the above; the concentration of NH4Cl can be 0.30 g / L, 0.80 g / L, 1.00 g / L, 2.00 g / L, 3.00 g / L, 4.00 g / L, 5.00 g / L, 6.00 g / L, or any concentration between two of the above.

[0009] In this application, the HOB fermentation medium comprises, in concentrations of: 4.50 g / L Na2HPO4×12H2O, 0.75 g / L KH2PO4, 0.20 g / L MgSO4×7H2O, 0.03 g / L CaCl2×2H2O, 18.00 mg / L ferric ammonium citrate, and 1 mL / L trace element solution.

[0010] Based on the above-mentioned HOB fermentation medium, the raw materials for preparing simulated biogas slurry include: 7.00 g / L CH3COONa, 3.00 g / L NH4Cl, 4.50 g / L Na2HPO4×12H2O, 0.75 g / L KH2PO4, 0.20 g / L MgSO4×7H2O, 0.03 g / L CaCl2×2H2O, 18.00 mg / L ferric ammonium citrate, and 1 mL / L trace element solution.

[0011] In the simulated biogas slurry and HOB fermentation medium, the trace element solutions, according to their concentrations, included: 0.10 g / L ZnSO4×7H2O, 0.03 g / L MnCl2×4H2O, 0.30 g / L H3BO3, 0.20 g / L CoCl2×6H2O, 0.01 g / L CuCl2×2H2O, 0.02 g / L NiCl2×6H2O, and 0.03 g / L Na2MoO4×2H2O.

[0012] In this application, the operating temperature of the system is 25-35℃ and the operating voltage is 0.5-1.5V. More preferably, the operating temperature of the system is 30℃ and the operating voltage is 1V.

[0013] Secondly, the system in this application for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria is used for co-producing single-cell protein.

[0014] Thirdly, this application provides a method for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria, the method comprising: S01: Both the anode and cathode chambers are filled with organic wastewater, and the HOB fermentation medium is placed in the intermediate chamber.

[0015] S02: A constant voltage of 1V is applied to the anode and cathode ends in the anode and cathode chambers. Under the temperature of 30℃ and the electric field drive, ammonia nitrogen and acetic acid in organic wastewater are recovered to the intermediate chamber through cation exchange membrane and anion exchange membrane, respectively.

[0016] S03: After running for a period of time, inoculate 5 mL of hydroxide bacteria solution into the HOB fermentation medium, so that the hydroxide bacteria can ferment and produce single-cell protein using the recovered ammonia nitrogen and acetic acid as fermentation substrates.

[0017] In this application, the system for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria has an operating cycle of 15 days.

[0018] Furthermore, a peristaltic pump is used to circulate the organic wastewater, so as to fully recover nutrients such as ammonia nitrogen and acetic acid in the organic wastewater and improve the treatment efficiency of organic wastewater.

[0019] The present invention has the following beneficial effects: (1) In this application, an anode chamber, an intermediate chamber, and a cathode chamber are formed by separating them through a cation exchange membrane and an anion exchange membrane. Both the anode chamber and the cathode chamber are filled with organic wastewater, and the intermediate chamber contains HOB and HOB fermentation medium. Under the drive of an electric field, ammonium ions and acetate ions in the organic wastewater are recovered to the intermediate chamber through the cation and anion exchange membranes, respectively, and are then used by HOB for fermentation to produce single-cell protein, thus realizing the in-situ recovery and resource utilization of nutrients.

[0020] (2) The peristaltic pump can realize the recycling of organic wastewater in the anode and cathode chambers, recover more ammonia nitrogen and acetate to the intermediate chamber, and then use HOB to produce SCP.

[0021] (3) In this application, the average recovery rate of acetic acid is 389.83 mg / L / d, the average recovery rate of ammonia nitrogen is 35 mg / L / d, the cell dry weight is 1.24 g / L, and the protein content is 61.7%.

[0022] (4) This application effectively combines the ED system with the microbial fermentation process, simultaneously realizing the recovery of nutrients in organic wastewater, treatment of organic wastewater and production of single-cell protein, effectively transforming the treatment burden into protein resources and completing the upgrading of nutrients in organic wastewater, with advantages of environmental protection, economy and sustainable development. Attached Figure Description

[0023] Figure 1 A schematic diagram of the system for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria, as provided in an embodiment of this application; Figure 2 The graph shows the changes in OD values ​​of the hydroxyl bacteria during the production of single-cell protein using the methods provided in Examples 4 and 5; where 1V represents Example 4 and P-1V represents Example 5. Figure 3 The graph shows the changes in cell dry weight and protein content during the production of single-cell protein using the methods provided in Examples 4 and 5; where 1V represents Example 4 and P-1V represents Example 5. Figure 4 The diagram shows the pH changes in the intermediate chamber during the production of single-cell protein using the methods provided in Examples 4 and 5; where 1V represents Example 4 and P-1V represents Example 5. Figure 5 This is a protein amino acid analysis diagram of the single-cell protein produced using the method provided in Example 4; Figure 6 This is a protein amino acid analysis diagram of the single-cell protein produced using the method provided in Example 5. Detailed Implementation

[0024] The hydroxide bacteria used in this embodiment were purchased from DSMZ (Leibniz Institute DSMZ - German Collection of Microbial and Cell Cultures GmbH). Hydrogenophaga pseudoflava Z-1107, with accession number DSM1084, is a hydroxide-producing bacterium capable of growing using available carbon and nitrogen sources and producing a high-value-added product—single-cell protein. The technical solution of this invention will be further explained and illustrated below through specific embodiments.

[0025] Example 1 This application provides a system for electrodialysis treatment of organic wastewater and co-production of single-cell protein by HOB fermentation. The system comprises an anode chamber, an intermediate chamber, and a cathode chamber separated by cation exchange membranes and anion exchange membranes. Both the anode and cathode chambers are filled with biogas slurry. The intermediate chamber contains HOB fermentation medium and HOB, as shown in the attached... Figure 1 As shown.

[0026] The HOB fermentation medium consists of the following components in concentration: 4.50 g / L Na2HPO4×12H2O, 0.75 g / L KH2PO4, 0.20 g / L MgSO4×7H2O, 0.03 g / L CaCl2×2H2O, 18.00 mg / L ferric ammonium citrate, and 1 mL / L trace element solution.

[0027] The biogas slurry used was a simulated biogas slurry, based on the concentration in the HOB fermentation medium. This simulated biogas slurry consisted of: 7.00 g / L CH3COONa, 3.00 g / L NH4Cl, 4.50 g / L Na2HPO4×12H2O, 0.75 g / L KH2PO4, 0.20 g / L MgSO4×7H2O, 0.03 g / L CaCl2×2H2O, 18.00 mg / L ferric ammonium citrate, and 1 mL / L trace element solution.

[0028] In this embodiment, the HOB fermentation medium and the simulated biogas slurry use the same trace element solution, which includes the following concentrations: 0.10 g / L ZnSO4×7H2O, 0.03 g / L MnCl2×4H2O, 0.30 g / L H3BO3, 0.20 g / L CoCl2×6H2O, 0.01 g / L CuCl2×2H2O, 0.02 g / L NiCl2×6H2O, and 0.03 g / L Na2MoO4×2H2O.

[0029] Example 2 This application provides a system for electrodialysis treatment of organic wastewater and co-production of single-cell protein by hydrochloric acid bacteria fermentation. The system consists of an anode chamber, an intermediate chamber, and a cathode chamber separated by a cation exchange membrane and an anion exchange membrane. Both the anode chamber and the cathode chamber are filled with biogas slurry. The intermediate chamber contains HOB fermentation medium and hydrochloric acid bacteria.

[0030] The HOB fermentation medium, biogas slurry, and trace element solution contained therein were the same as in Example 1, except that the concentration of CH3COONa in the biogas slurry was 0.30 g / L and the concentration of NH4Cl was 0.30 g / L.

[0031] Example 3 This application provides a system for electrodialysis treatment of organic wastewater and co-production of single-cell protein by hydrochloric acid bacteria fermentation. The system consists of an anode chamber, an intermediate chamber, and a cathode chamber separated by a cation exchange membrane and an anion exchange membrane. Both the anode chamber and the cathode chamber are filled with biogas slurry. The intermediate chamber contains HOB fermentation medium and hydrochloric acid bacteria.

[0032] The HOB fermentation medium, biogas slurry, and trace element solutions contained therein were the same as in Example 1, except that the concentration of CH3COONa in the biogas slurry was 10.00 g / L and the concentration of NH4Cl was 6.00 g / L.

[0033] Example 4 The system described in Example 1, which combines electrodialysis treatment of organic wastewater with fermentation by hydroxide bacteria to produce single-cell protein, was used to produce single-cell protein. Specifically, a constant voltage of 1V was applied to the anode and cathode terminals in the anode and cathode chambers, respectively. Under the influence of a temperature of 30°C and an electric field, ammonia nitrogen and acetic acid in the simulated biogas slurry were recovered to the intermediate chamber through cation exchange membranes and anion exchange membranes, respectively. After 2 days of operation, 5 mL of hydroxide bacteria culture was inoculated into the HOB fermentation medium to allow the hydroxide bacteria to grow and ferment using the recovered ammonia nitrogen and acetic acid as fermentation substrates to produce single-cell protein.

[0034] Example 5 The system for co-producing single-cell protein using electrodialysis to treat organic wastewater and fermentation with hydroxide bacteria, as described in Example 1, is used. The specific process is the same as in Example 4, except that simulated biogas slurry is circulated using a peristaltic pump.

[0035] During the operation of the systems provided in Examples 4 and 5, samples were taken every 24 hours to analyze the changes in OD value, pH value, cell dry weight, and protein content of the hydroxide bacteria in the intermediate chamber, and to obtain the attached... Figure 2-4 Meanwhile, the migration rates and recovery rates of ammonia nitrogen and acetic acid were calculated, and the results are shown in Table 1.

[0036] Table 1: Migration and recovery rates of ammonia nitrogen and acetic acid As shown in Table 1, compared with Example 4 without the addition of a peristaltic pump, the average migration rate and average recovery rate of acetic acid and ammonia nitrogen were significantly improved in Example 5 after the addition of a peristaltic pump. The average recovery rate of acetic acid reached 389.83 mg / L / d, and the average recovery rate of ammonia nitrogen reached 35 mg / L / d.

[0037] From the appendix Figure 2 It can be seen that when the system running time is less than 4 days, the OD in Example 5, which includes a peristaltic pump, is... 600 The value is greater than the OD in Example 4 without a peristaltic pump. 600Value; when the system uptime is ≥4 days, the OD in Example 4 without a peristaltic pump 600 The value gradually increased. This indicates that the hydroxide bacteria in Example 4 effectively produced biomass through substrate fermentation, and its OD value... 600 The value reached 4.6. In Example 5, although the peristaltic pump improved the mass transfer efficiency of the simulated biogas slurry, its OD value was lower than that of Example 4. When the system had been running for 10 days, the OD value of Example 5 was... 600 The pH value was 2.1, which had an adverse effect on its growth.

[0038] From the appendix Figure 3 As can be seen, after running the method in Example 4 for 12 days, the cell dry weight was approximately 1.23 g / L, and the protein content was 61.7%. After running the method in Example 5 for 12 days, the cell dry weight was approximately 0.5 g / L, and the protein content was 49%.

[0039] From the appendix Figure 4 It is evident that when the system operating time is ≥1 day, the pH value of the intermediate chamber in Example 5, which includes a peristaltic pump, is higher than that in Example 4, which does not contain a peristaltic pump. Although the average migration rate and average recovery rate of acetic acid and ammonia nitrogen are relatively high in Example 5, the large and gradually increasing pH value in the intermediate chamber leads to a more alkaline solution. This alkaline environment inhibits the growth of hydroxide bacteria, resulting in a decrease in the OD of hydroxide bacteria. 600 The values ​​were lower than in Example 4, and the cell dry weight and protein content were also lower than in Example 4. This indicates that the acetic acid and ammonia nitrogen recovered into the intermediate chamber in Example 5 were not fully utilized.

[0040] To determine the quality of SCP produced by the hydroxide bacteria, the amino acid composition of the single-cell protein produced by the methods provided in Examples 4 and 5 was also analyzed in the embodiments of this application, as shown in the appendix. Figure 5 , 6 As shown. (From the appendix) Figure 5 , 6 As can be seen, the single-cell proteins produced by the methods provided in Examples 4 and 5 both contain 8 essential amino acids and 8 non-essential amino acids. Glutamic acid and aspartic acid are present in the highest amounts, while leucine is the most abundant essential amino acid, and tyrosine, methionine, and histidine are present in the lowest concentrations. Glutamic acid can act as an excitatory neurotransmitter in the central nervous system, aspartic acid participates in protein charge interactions, and leucine plays an irreplaceable role in protein structural stability, metabolic regulation, and signal transduction.

[0041] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A system for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria, characterized in that, include: An anode chamber, an intermediate chamber, and a cathode chamber are formed by separating them with cation exchange membranes and anion exchange membranes; both the anode chamber and the cathode chamber are filled with organic wastewater; and HOB and HOB fermentation medium are placed in the intermediate chamber.

2. The system for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria according to claim 1, characterized in that, The organic wastewater is rich in organic acids and ammonia nitrogen.

3. The system for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria according to claim 2, characterized in that, The organic wastewater includes food processing wastewater, aquaculture wastewater, chemical production wastewater, and biogas slurry or simulated biogas slurry produced by fermentation of organic solid waste.

4. The system for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria according to claim 3, characterized in that, The simulated biogas slurry includes: CH3COONa, NH4Cl, and the HOB fermentation medium.

5. The system for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria according to claim 4, characterized in that, Based on the concentrations in the HOB fermentation medium, the concentrations of CH3COONa and NH4Cl are 0.30-10.00 g / L and 0.30-6.00 g / L, respectively.

6. The system for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria according to claim 1, characterized in that, The system operates at a temperature of 25-35℃ and a voltage of 0.5-1.5V.

7. The system for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria as described in any one of claims 1-6 is used for co-producing single-cell protein.

8. A method for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria, characterized in that, The system for treating organic wastewater by electrodialysis and co-producing single-cell protein by hydrogen hydroxide fermentation according to any one of claims 1-6, the method comprising: Organic wastewater was filled into both the anode and cathode chambers, and HOB fermentation medium was placed in the intermediate chamber. A voltage is applied to the anode and cathode ends in the anode and cathode chambers to allow ammonia nitrogen and acetic acid in the organic wastewater to be recovered into the intermediate chamber through cation exchange membranes and anion exchange membranes; Hydroxyhydrogen bacteria are inoculated into the HOB fermentation medium so that the hydroxyhydrogen bacteria can ferment and produce single-cell protein using the recovered ammonia nitrogen and acetic acid.

9. The method for co-producing single-cell protein by electrodialysis treatment of organic wastewater and fermentation with hydroxide bacteria according to claim 8, characterized in that, The organic wastewater is circulated between the anode and cathode chambers using a pump circulation system.

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