A forward osmosis assisted three-chamber bioelectrochemical system and a method for synergistically high-value kitchen waste with microalgae

Abstract

The application discloses a forward osmosis assisted three-chamber bioelectrochemical system and a method for synergistically high-valued kitchen waste with microalgae, and relates to the technical field of organic waste resource utilization. The method comprises the following steps: after the kitchen waste is washed, anaerobic sludge is inoculated for fermentation, the supernatant is taken after centrifugation, and is added into a cathode chamber and an anode chamber respectively; trace element supplements are added into a middle chamber for operation; the obtained fermentation liquor is used as a feed liquid, a sodium chloride solution is used as a draw solution, concentration is performed through a forward osmosis module, then Chlorella vulgaris and Haematococcus pluvialis liquid culture are inoculated, centrifugation is performed, the algal sludge is dissolved by sodium acetate, and induction is performed; the Chlorella vulgaris generates biodiesel and amino acids, and the Haematococcus pluvialis generates astaxanthin. The application regulates and controls the kitchen waste fermentation, recovers and concentrates through the three-chamber bioelectrochemical system and forward osmosis, and outputs high-value products, effectively solving the problem that the anaerobic fermentation liquor of the kitchen waste is difficult to be directly used for clean culture of microalgae and has low high-value conversion efficiency due to unsuitable concentration and easy pollution.

Description

Technical Field

[0001] This invention relates to the field of organic waste resource utilization technology, specifically to a forward osmosis-assisted three-chamber bioelectrochemical system and a method for synergistically utilizing microalgae to extract high-value food waste. Background Technology

[0002] The production of food waste has surged, and its rich organic matter is prone to decay and the breeding of pathogens. Traditional landfill and incineration methods result in resource waste and secondary pollution. Anaerobic fermentation, which can reduce waste volume and produce high-value products such as volatile fatty acids (VFAs), has become one of the important technologies for the resource utilization of food waste. In recent years, technologies that utilize microalgae to treat wastewater and simultaneously synthesize high-value products such as biodiesel and protein have been continuously developing. However, directly introducing microalgae into the fermentation broth of food waste faces the following problems: excessively high or low concentrations of the fermentation broth affect microalgae growth, inhibit their growth and metabolism, and may contaminate the algae. Therefore, it is imperative to construct a novel cultivation system that can achieve efficient nutrient recovery and reduce the inhibitory effect of the fermentation broth on microalgae growth. Summary of the Invention

[0003] To address the aforementioned shortcomings in existing technologies, this invention provides a forward osmosis-assisted three-chamber bioelectrochemical system and a method for synergistically transforming kitchen waste with microalgae into high-value products. This effectively solves the problems of unsuitable concentration and easy contamination of anaerobic fermentation liquid from kitchen waste, making it difficult to directly use for clean microalgae cultivation and resulting in low high-value transformation efficiency.

[0004] To achieve the above objectives, the technical solution adopted by the present invention to solve its technical problem is as follows: a three-chamber bioelectrochemical system is provided, including an anode chamber, an intermediate chamber and a cathode chamber. An anode is disposed in the anode chamber and a cathode is disposed in the cathode chamber. The anode and cathode are connected to an external power supply through an alligator clamp. A resistor is connected in series in the circuit. The anode chamber and the intermediate chamber are separated by a cation exchange membrane, and the intermediate chamber and the cathode chamber are separated by an anion exchange membrane.

[0005] Furthermore, the anode chamber, intermediate chamber, and cathode chamber are composed of three plexiglass modules.

[0006] Furthermore, the plexiglass module, cation exchange membrane, and anion exchange membrane are connected in series via four threaded rods.

[0007] Furthermore, the anode is a titanium electrode mesh with a size of 4 cm × 4 cm coated with IrO2.

[0008] Furthermore, the cathode is a 4 cm × 4 cm titanium mesh.

[0009] Furthermore, silicone pads are provided on both sides of the cation exchange membrane and the anion exchange membrane.

[0010] The beneficial effect of taking the above-mentioned further measures is to ensure the sealing performance of the system.

[0011] Furthermore, magnetic stirrers are installed in the anode chamber, intermediate chamber, and cathode chamber.

[0012] The beneficial effect of taking the above-mentioned further measures is to maintain the homogeneity of the solution.

[0013] A method for synergistically utilizing microalgae with a forward osmosis-assisted three-compartment bioelectrochemical system to extract high-value food waste, characterized by the following steps: S1. After washing and stirring the kitchen waste, inoculate it with anaerobic sludge and dilute it to obtain a mixture. Then, adjust the solids content and pH value and ferment it to obtain the fermented product. S2. Centrifuge the fermentation product obtained in step S1, take the supernatant, adjust the pH value, and then add it to the cathode chamber and anode chamber respectively. Then add the trace element supplement to the intermediate chamber to start the operation and obtain the kitchen waste fermentation liquid. S3. Using the fermented liquid of kitchen waste obtained in step S2 as the feed liquid and sodium chloride solution as the absorbent liquid, the liquid is concentrated through a forward osmosis module to obtain concentrated liquid. S4. After diluting the concentrated solution obtained in step S3, inoculate Chlorella and Haematococcus pluvialis solutions and culture them. Then, centrifuge the algal solutions, take the algal mud, dissolve it with sodium acetate, and induce it. Chlorella produces biodiesel and amino acids, while Haematococcus pluvialis produces astaxanthin.

[0014] Furthermore, in step S1, the food waste includes 30-40 portions of staple starch, 40-50 portions of vegetables, and 15-25 portions of protein.

[0015] Furthermore, in step S1, the food waste includes 35 portions of staple starch, 45 portions of vegetables, and 20 portions of protein.

[0016] Furthermore, in step S2, the staple starches include rice, noodles, and rice noodles.

[0017] Furthermore, in step S2, the vegetables are cellulose-rich vegetables. Furthermore, in step S2, the vegetables include leafy greens, cauliflower, and carrots.

[0018] Furthermore, in step S2, the protein sources include meat, tofu, and eggs.

[0019] Furthermore, anaerobic sludge refers to the anaerobic sludge produced in the anaerobic tower of a wastewater treatment plant.

[0020] Further, in step S1, the mixture is stirred into a paste.

[0021] Further, in step S1, the mixture is diluted with ultrapure water.

[0022] Furthermore, in step S1, the volume ratio of anaerobic sludge to kitchen waste is 4:1.

[0023] Furthermore, in step S1, the solids content of the mixture is 2%.

[0024] Furthermore, in step S1, the pH value is adjusted to 11, and the mixture is allowed to stand in an anaerobic environment for 24 hours. Then, the pH value is adjusted to 5, and the mixture is anaerobic fermented at 35°C for 5 days. During this period, the pH value of the system is corrected every 12 hours.

[0025] Furthermore, in step S1, the volume of the mixture in the fermentation flask is 200 mL, with a headspace volume of 50 mL reserved.

[0026] Furthermore, in step S2, centrifuge at 4000-5000 r / min for 15-25 min.

[0027] Furthermore, in step S2, centrifuge at 4500 r / min for 20 min.

[0028] Furthermore, in step S2, the pH value is adjusted to neutral.

[0029] Further, in step S2, 200 mL of supernatant is added to the cathode chamber and the anode chamber respectively.

[0030] Further, in step S2, 200 mL of trace element supplement is added to the intermediate chamber.

[0031] Furthermore, in step S2, the trace element supplement is BG-11 culture medium that does not contain carbon, nitrogen, or phosphorus elements.

[0032] Furthermore, in step S2, the running time is 10-12 days.

[0033] Furthermore, in step S3, the concentration of the sodium chloride solution is 1.5-2.5 M.

[0034] Furthermore, in step S3, the concentration of the sodium chloride solution is 2 M.

[0035] Furthermore, in step S3, the volume of the feed liquid and the draw liquid is 400 mL.

[0036] Furthermore, in step S3, the forward osmosis module includes: a feed liquid bottle, a draw liquid bottle, and two acrylic glass component modules. A forward osmosis membrane is disposed between the two acrylic glass component modules. Silicone gaskets are disposed between the two sides of the forward osmosis membrane and the acrylic glass component modules. The first inlet and outlet water interfaces of the acrylic glass component modules are connected to peristaltic pump one and peristaltic pump two through rubber tubes. A feed inlet is provided on the draw liquid bottle.

[0037] Furthermore, the two acrylic glass component modules are fixed together by threaded rods.

[0038] The beneficial effect of taking the above-mentioned further measures is to ensure a tight fit and seal between components.

[0039] Furthermore, the active side of the forward osmosis membrane faces the feed bottle side.

[0040] Furthermore, both the fermentation broth and the extract liquid enter the interior of organic module one and organic module two through the inlet and outlet water interfaces, enter the channel made of silicone gasket, and contact the forward osmosis membrane. The water flows in opposite directions on both sides of the membrane. Water molecules pass through the forward osmosis membrane from the feed liquid side and enter the extract liquid side. After the liquids on both sides contact the forward osmosis membrane, they flow out from the outlet and return to the bottle, forming a continuous circulation flow by the peristaltic pump.

[0041] Furthermore, the forward osmosis module also includes: inlet and outlet water channels inside the component, threaded rod fixing holes, and inlet and outlet water channels on the membrane side.

[0042] Furthermore, in step S3, the concentration process involves a flow rate of 80-100 mL / min and a time of 5-7 h.

[0043] Furthermore, in step S3, the concentration process is carried out at a flow rate of 90 mL / min for 6 h.

[0044] Further, in step S4, the concentrate is diluted by two times.

[0045] Furthermore, in step S4, 300 mL of OD is inoculated respectively. 680 Chlorella and Haematococcus pluvialis solutions with a concentration of 0.2 were placed in 500 mL Erlenmeyer flasks and cultured for 10 days.

[0046] Furthermore, in step S4, during cultivation, the light intensity is 4500-5500 Lux, and the light-dark ratio is 14 h:10 h.

[0047] Furthermore, in step S4, during cultivation, the light intensity is 5000 Lux and the light-dark ratio is 14 h:10 h.

[0048] Furthermore, in step S4, the soil is shaken three times daily during cultivation.

[0049] Furthermore, in step S4, the centrifugation speed is 4000-5000 r / min and the time is 10-20 min.

[0050] Furthermore, in step S4, the centrifugation speed is 4500 r / min and the time is 15 min.

[0051] Furthermore, in step S4, the concentration of sodium acetate is 0.1-0.2 g / L.

[0052] Furthermore, in step S4, the concentration of sodium acetate is 0.1 g / L.

[0053] Furthermore, in step S4, during induction, magnetic stirring is used to maintain the uniformity of the algal solution.

[0054] Furthermore, in step S4, the light intensity during induction is 10,000-20,000 Lux, and the time is 10 days.

[0055] Furthermore, in step S4, the light intensity during induction is 15000 Lux, and the time is 10-15 days.

[0056] In summary, the present invention has the following beneficial effects: 1. This invention aims to achieve high-value transformation of kitchen waste through the metabolic activities of microalgae, based on the anaerobic fermentation and harmless treatment of kitchen waste. Anaerobic fermentation of kitchen waste is performed under specific conditions to directionally produce volatile fatty acids. The system couples kitchen waste resource recovery with microalgae treatment technology, achieving synergistic progress in both harmless treatment and high-value transformation of kitchen waste, thus providing a new technical path for the resource utilization of kitchen waste. A three-chamber bioelectrochemical device is constructed to establish a nutrient transport channel, efficiently recovering nutrients from the fermentation effluent of kitchen waste. While ensuring efficient nutrient transport in the fermentation liquid, the microalgae are isolated from the fermentation liquid for cultivation, thereby improving the cleanliness of the microalgae culture. Forward osmosis membrane concentration technology is used to replace the traditional pressurized membrane concentration process, achieving low-energy concentration of the fermentation effluent without external pressure. This effectively avoids the technical bottlenecks of high energy consumption and membrane fouling associated with traditional methods, achieving energy-saving and efficient concentration treatment of the fermentation liquid, providing technical support for subsequent resource utilization, and demonstrating innovation and practicality in process optimization. This invention utilizes a concentrated solution for microalgae cultivation, achieving clean cultivation that avoids microalgae contamination while simultaneously producing astaxanthin and biodiesel, thus completing the high-value conversion of food waste. This invention not only achieves the harmless treatment and resource utilization of food waste but also broadens the pathways for green energy development.

[0057] 2. This invention regulates the anaerobic fermentation conditions of food waste to produce volatile fatty acids (VFAs). After recovery and concentration via a three-chamber bioelectrochemical system and forward osmosis, the VFAs are used for clean cultivation of microalgae, yielding high-value products and achieving high-value conversion of food waste. By adjusting the pH to 5, solids content to 2%, inoculum ratio to 4:1, and with alkali pretreatment, 3.2 g dry weight of food waste underwent anaerobic fermentation in small vials for 5 days, achieving a VFA yield of 8.14 g / L. The fermentation broth recovered by the three-chamber bioelectrochemical system was concentrated using a forward osmosis module, and after 6 hours of operation, the VFA concentration in the fermentation broth reached 1.24 times the initial concentration. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the structure of a three-chamber bioelectrochemical device; Figure 2 This is a schematic diagram of the forward osmosis module. Figure 3 Figures showing the growth of Chlorella and Haematococcus pluvialis under different culture conditions; Figure 4 The graph shows the consumption of nutrients in the fermentation broth by the two algal species during the cultivation process. Among them, 101 is an external power supply; 102 is a resistor; 103 is an anode chamber; 104 is an anode; 105 is an intermediate chamber; 106 is a silicone gasket; 107 is a cathode; 108 is a cathode chamber; 109 is a magnetic stir bar; 110 is a cation exchange membrane; and 111 is an anion exchange membrane. 201. Peristaltic pump one; 202. Forward osmosis membrane; 203. Peristaltic pump two; 204. Threaded rod; 205. Acrylic glass assembly module; 206. Feed port; 207. Feed bottle; 208. First inlet / outlet water interface; 209. Silicone gasket; 210. Draw liquid bottle; 211. Second inlet / outlet water interface; 212. Organic module one; 213. Organic module two; 214. Inlet / outlet water channel; 215. Threaded rod fixing hole; 216. Inlet / outlet water channel on the membrane side. Detailed Implementation

[0059] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0060] Example 1 A three-chamber bioelectrochemical system is characterized by comprising an anode chamber 103, an intermediate chamber 105, and a cathode chamber 108. An anode 104 is disposed within the anode chamber 103, and a cathode 107 is disposed within the cathode chamber 108. The anode 104 and cathode 107 are connected to an external power supply 101 via alligator clamps. A resistor 102 is connected in series in the circuit. The anode chamber 103 and intermediate chamber 105 are separated by a cation exchange membrane 110, and the intermediate chamber 105 and cathode chamber 108 are separated by an anion exchange membrane 111. The anode chamber 103, intermediate chamber 105, and cathode chamber 108 are each composed of three acrylic glass modules. The acrylic glass modules, the cation exchange membrane 110, and the anion exchange membrane 111 are connected in series via four threaded rods. The anode 104 is a 4 cm × 4 cm titanium electrode mesh coated with IrO2, and the cathode 107 is also 4 cm × 4 cm. A titanium mesh of cm thickness; silicone gaskets 106 are provided on both sides of the cation exchange membrane 110 and the anion exchange membrane 111; magnetic stir bar 109 is provided in the anode chamber 103, the intermediate chamber 105 and the cathode chamber 108. A schematic diagram of the three-chamber bioelectrochemical system is shown below. Figure 1 As shown.

[0061] A method for synergistically utilizing microalgae with a forward osmosis-assisted three-compartment bioelectrochemical system to extract high-value food waste includes the following steps: S1. After washing the kitchen waste, stir it into a paste. The kitchen waste includes 35 parts of staple starch, 45 parts of vegetables, and 20 parts of protein. The staple starch includes rice, noodles, and rice noodles. The vegetables include leafy greens, cauliflower, and carrots. The protein includes meat, tofu, and eggs. After inoculating with anaerobic sludge, dilute with ultrapure water. The anaerobic sludge is produced from the anaerobic tower of the sewage treatment plant. The volume ratio of anaerobic sludge to kitchen waste is 4:1 to obtain a mixture. Then adjust the solids content to 2% and the pH value to 11. Let it stand in an anaerobic environment for 24 hours. Then adjust the pH value to 5 and anaerobic ferment at 35℃ for 5 days. During this period, the pH value of the system is corrected every 12 hours. The volume of the mixture in the fermentation bottle is 200 mL, with 50 mL reserved for headspace volume to obtain the fermentation product. S2. Centrifuge the fermentation product obtained in step S1 at 4500 r / min for 20 min, take the supernatant, adjust the pH to neutral, and then take 200 mL of each and add them to the cathode chamber and anode chamber respectively. Then add BG-11 medium without carbon, nitrogen and phosphorus elements to the intermediate chamber and start running for 10 days to obtain the kitchen waste fermentation liquid. S3. Using the fermented liquid from kitchen waste obtained in step S2 as the feed liquid and sodium chloride solution as the draw liquid, the total volume of the feed liquid and draw liquid is 400 mL, and the concentration of the sodium chloride solution is 2 M. The solution is concentrated using a forward osmosis module to obtain a concentrated liquid. The concentration flow rate is 90 mL / min, and the time is 6 h. The forward osmosis module includes: a feed liquid bottle 207, a draw liquid bottle 210, and two acrylic glass component modules 205. A forward osmosis membrane 202 is placed between the two acrylic glass component modules 205. Silicone gaskets 209 are placed between the two sides of the forward osmosis membrane 202 and the acrylic glass component modules 205. The first inlet and outlet water interfaces 208 of the acrylic glass component modules 205 are connected to peristaltic pump 1 201 and peristaltic pump 203 via rubber tubes. A feed inlet 206 is provided on the draw liquid bottle 210. The two acrylic glass component modules 205 are fixed together by threaded rods 204. Furthermore, the active side of the forward osmosis membrane 202... Facing the feed bottle 207, both the fermentation broth and the absorbent enter the organic module 1 213 and organic module 2 214 through the inlet / outlet water interfaces 212, entering the channel made of the silicone gasket 211 and contacting the forward osmosis membrane 215. The water flows in opposite directions on both sides of the membrane. Water molecules pass through the forward osmosis membrane from the feed side and enter the absorbent side. After contacting the forward osmosis membrane, the liquids on both sides flow out from their respective outlets and return to the bottle, forming a continuous circulation flow through a peristaltic pump. The forward osmosis module also includes: an inlet / outlet water channel 216 inside the module, a threaded rod fixing hole 217, and an inlet / outlet water channel 218 on the membrane side. A schematic diagram of the forward osmosis module is shown below. Figure 2 As shown, Figure 2 In the diagram, (a) is the overall structure diagram, (b) is the longitudinal section of the flow path, and (c) is the front view of a single-sided module. S4. Dilute the concentrated solution obtained in step S3 to twice its original volume, and inoculate 300 mL OD solution into each solution. 680 Chlorella and Haematococcus pluvialis solutions with a concentration of 0.2 were placed in 500 mL Erlenmeyer flasks and cultured for 10 days. During culture, the light intensity was 5000 Lux, the light-dark ratio was 14 h:10 h, and the flasks were shaken 3 times a day. The algal solutions were then centrifuged at 4500 r / min for 15 min. The algal sludge was then dissolved in sodium acetate at a concentration of 0.1 g / L for induction. During induction, magnetic stirring was used to maintain the uniformity of the algal solutions. The light intensity was 15000 Lux, and the induction time was 10 days. Chlorella produced biodiesel and amino acids, while Haematococcus pluvialis produced astaxanthin.

[0062] Example 2 A three-chamber bioelectrochemical system is characterized by comprising an anode chamber 103, an intermediate chamber 105, and a cathode chamber 108. An anode 104 is disposed within the anode chamber 103, and a cathode 107 is disposed within the cathode chamber 108. The anode 104 and cathode 107 are connected to an external power supply 101 via alligator clamps. A resistor 102 is connected in series in the circuit. The anode chamber 103 and intermediate chamber 105 are separated by a cation exchange membrane 110, and the intermediate chamber 105 and cathode chamber 108 are separated by an anion exchange membrane 111. The anode chamber 103, intermediate chamber 105, and cathode chamber 108 are each composed of three acrylic glass modules. The acrylic glass modules, the cation exchange membrane 110, and the anion exchange membrane 111 are connected in series via four threaded rods. The anode 104 is a 4 cm × 4 cm titanium electrode mesh coated with IrO2, and the cathode 107 is also 4 cm × 4 cm. A titanium mesh of cm; silicone gaskets 106 are provided on both sides of the cation exchange membrane 110 and the anion exchange membrane 111; magnetic stir bar 109 is provided in the anode chamber 103, the intermediate chamber 105 and the cathode chamber 108.

[0063] A method for synergistically utilizing microalgae with a forward osmosis-assisted three-compartment bioelectrochemical system to extract high-value food waste includes the following steps: S1. After washing the kitchen waste, stir it into a paste. The kitchen waste includes 30 parts of staple starch, 40 parts of vegetables, and 15 parts of protein. The staple starch includes rice, noodles, and rice noodles. The vegetables include leafy greens, cauliflower, and carrots. The protein includes meat, tofu, and eggs. After inoculating with anaerobic sludge, dilute with ultrapure water. The anaerobic sludge is produced from the anaerobic tower of the sewage treatment plant. The volume ratio of anaerobic sludge to kitchen waste is 4:1 to obtain a mixture. Then adjust the solids content to 2% and the pH value to 11. Let it stand in an anaerobic environment for 24 hours. Then adjust the pH value to 5 and anaerobic ferment at 35℃ for 5 days. During this period, the pH value of the system is corrected every 12 hours. The volume of the mixture in the fermentation bottle is 200 mL, with 50 mL reserved for headspace volume to obtain the fermentation product. S2. Centrifuge the fermentation product obtained in step S1 at 4000 r / min for 15 min, take the supernatant, adjust the pH to neutral, and then take 200 mL of each and add them to the cathode chamber and anode chamber respectively. Then add BG-11 medium without carbon, nitrogen and phosphorus elements to the intermediate chamber and start running for 11 days to obtain the kitchen waste fermentation liquid. S3. Using the fermented liquid from kitchen waste obtained in step S2 as the feed liquid and sodium chloride solution as the draw liquid, the total volume of the feed liquid and draw liquid is 400 mL. The concentration of the sodium chloride solution is 1.5 M. The solution is concentrated using a forward osmosis module to obtain a concentrated liquid. The concentration flow rate is 80 mL / min, and the concentration time is 5 minutes. h. The forward osmosis module includes: a feed liquid bottle 207, a draw liquid bottle 210, and two acrylic glass component modules 205. A forward osmosis membrane 202 is disposed between the two acrylic glass component modules 205. Silicone gaskets 209 are disposed between the two sides of the forward osmosis membrane 202 and the acrylic glass component modules 205. The first inlet / outlet water interface 208 of the acrylic glass component module 205 is connected to peristaltic pump 1 201 and peristaltic pump 203 through rubber tubes. A feed inlet 206 is provided on the draw liquid bottle 210. The two acrylic glass component modules 205 are fixed together by threaded rods 204. Furthermore, the active side of the forward osmosis membrane 202 faces the feed liquid bottle 207. Both the fermentation broth and the draw liquid enter the interior of organic module 1 213 and organic module 2 214 through the inlet / outlet water interface 212, enter the channel made by the silicone gasket 211, and contact the forward osmosis membrane 215. The water flows in opposite directions on both sides of the membrane. Water molecules pass through the forward osmosis membrane from the feed liquid side and enter the draw liquid side. After the liquids on both sides come into contact with the forward osmosis membrane, they flow out from the outlet and return to the bottle. The peristaltic pump forms a continuous circulation. The forward osmosis module also includes: water inlet and outlet channels 216 inside the component, threaded rod fixing holes 217 and water inlet and outlet channels 218 on the membrane side. S4. Dilute the concentrated solution obtained in step S3 to twice its original volume, and inoculate 300 mL OD solution into each solution. 680 Chlorella and Haematococcus pluvialis solutions with a concentration of 0.2 were placed in 500 mL Erlenmeyer flasks and cultured for 10 days. During culture, the light intensity was 4500 Lux, the light-dark ratio was 14 h:10 h, and the flasks were shaken 3 times a day. The algal solutions were then centrifuged at 4000 r / min for 10 min. The algal sludge was then dissolved in sodium acetate at a concentration of 0.1 g / L for induction. During induction, magnetic stirring was used to maintain the uniformity of the algal solutions. The light intensity was 10000 Lux, and the induction time was 12 days. Chlorella produced biodiesel and amino acids, while Haematococcus pluvialis produced astaxanthin.

[0064] Example 3 A three-chamber bioelectrochemical system is characterized by comprising an anode chamber 103, an intermediate chamber 105, and a cathode chamber 108. An anode 104 is disposed within the anode chamber 103, and a cathode 107 is disposed within the cathode chamber 108. The anode 104 and cathode 107 are connected to an external power supply 101 via alligator clamps. A resistor 102 is connected in series in the circuit. The anode chamber 103 and intermediate chamber 105 are separated by a cation exchange membrane 110, and the intermediate chamber 105 and cathode chamber 108 are separated by an anion exchange membrane 111. The anode chamber 103, intermediate chamber 105, and cathode chamber 108 are each composed of three acrylic glass modules. The acrylic glass modules, the cation exchange membrane 110, and the anion exchange membrane 111 are connected in series via four threaded rods. The anode 104 is a 4 cm × 4 cm titanium electrode mesh coated with IrO2, and the cathode 107 is also 4 cm × 4 cm. A titanium mesh of cm; silicone gaskets 106 are provided on both sides of the cation exchange membrane 110 and the anion exchange membrane 111; magnetic stir bar 109 is provided in the anode chamber 103, the intermediate chamber 105 and the cathode chamber 108.

[0065] A method for synergistically utilizing microalgae with a forward osmosis-assisted three-compartment bioelectrochemical system to extract high-value food waste includes the following steps: S1. After washing the kitchen waste, stir it into a paste. The kitchen waste includes 40 parts of staple starch, 50 parts of vegetables, and 25 parts of protein. The staple starch includes rice, noodles, and rice noodles. The vegetables include leafy greens, cauliflower, and carrots. The protein includes meat, tofu, and eggs. After inoculating with anaerobic sludge, dilute with ultrapure water. The anaerobic sludge is produced from the anaerobic tower of the sewage treatment plant. The volume ratio of anaerobic sludge to kitchen waste is 4:1 to obtain a mixture. Then adjust the solids content to 3% and the pH value to 11. Let it stand in an anaerobic environment for 24 hours. Then adjust the pH value to 5 and anaerobic ferment at 35℃ for 5 days. During this period, the pH value of the system is corrected every 12 hours. The volume of the mixture in the fermentation bottle is 200 mL, with 50 mL reserved for headspace volume to obtain the fermentation product. S2. Centrifuge the fermentation product obtained in step S1 at 5000 r / min for 25 min, take the supernatant, adjust the pH to neutral, and then take 200 mL of each and add them to the cathode chamber and anode chamber respectively. Then add BG-11 medium without carbon, nitrogen and phosphorus elements to the intermediate chamber and start running for 12 days to obtain the kitchen waste fermentation liquid. S3. Using the fermented liquid from kitchen waste obtained in step S2 as the feed liquid and sodium chloride solution as the draw liquid, the total volume of the feed liquid and draw liquid is 400 mL. The concentration of the sodium chloride solution is 2.5 M. The solution is concentrated through a forward osmosis module to obtain a concentrated liquid. The flow rate during concentration is 100 mL / min, and the time is 7 minutes. h. The forward osmosis module includes: a feed liquid bottle 207, a draw liquid bottle 210, and two acrylic glass component modules 205. A forward osmosis membrane 202 is disposed between the two acrylic glass component modules 205. Silicone gaskets 209 are disposed between the two sides of the forward osmosis membrane 202 and the acrylic glass component modules 205. The first inlet / outlet water interface 208 of the acrylic glass component module 205 is connected to peristaltic pump 1 201 and peristaltic pump 203 through rubber tubes. A feed inlet 206 is provided on the draw liquid bottle 210. The two acrylic glass component modules 205 are fixed together by threaded rods 204. Furthermore, the active side of the forward osmosis membrane 202 faces the feed liquid bottle 207. Both the fermentation broth and the draw liquid enter the interior of organic module 1 213 and organic module 2 214 through the inlet / outlet water interface 212, enter the channel made by the silicone gasket 211, and contact the forward osmosis membrane 215. The water flows in opposite directions on both sides of the membrane. Water molecules pass through the forward osmosis membrane from the feed liquid side and enter the draw liquid side. After the liquids on both sides come into contact with the forward osmosis membrane, they flow out from the outlet and return to the bottle. The peristaltic pump forms a continuous circulation. The forward osmosis module also includes: water inlet and outlet channels 216 inside the component, threaded rod fixing holes 217 and water inlet and outlet channels 218 on the membrane side. S4. Dilute the concentrated solution obtained in step S3 to twice its original volume, and inoculate 300 mL OD solution into each solution. 680 Chlorella and Haematococcus pluvialis solutions with a concentration of 0.2 g / L were placed in 500 mL Erlenmeyer flasks and cultured for 10 days. During culture, the light intensity was 5500 Lux, the light-dark ratio was 14 h:10 h, and the flasks were shaken three times a day. The algal solutions were then centrifuged at 5000 r / min for 20 min. The algal sludge was then dissolved in sodium acetate at a concentration of 0.2 g / L for induction. During induction, magnetic stirring was used to maintain the uniformity of the algal solutions. The light intensity was 20000 Lux, and the induction time was 15 days. Chlorella produced biodiesel and amino acids, while Haematococcus pluvialis produced astaxanthin.

[0066] Experimental Example 1 The protocol provided in Example 1 was used to culture *Chlorella vulgaris* and *Haematococcus pluvialis*, with standard BG-11 medium as a control. OD 680 The absorbance value represents the light intensity of the algal cells; the higher the absorbance value, the greater the algal cell density. Results are as follows: Figure 3 As shown.

[0067] Depend on Figure 3It can be seen that the biomass accumulated by culturing Chlorella and Haematococcus pluvialis after the concentrated fermentation broth was diluted by 2 times was 191.39% and 184.06% of that of BG-11 culture, respectively.

[0068] Experimental Example 2 The analysis examined the consumption of nutrients in the fermentation broth by the two algal species during cultivation, including volatile fatty acids (VFA) and ammonium ions (NH4+). + ) and total phosphorus (TP). Results are as follows Figure 4 As shown.

[0069] Depend on Figure 4 It can be seen that using 3.2g of dry food waste, after fermentation in a small bottle, yields 8.144g / L of VFA. With a fermentation supernatant volume of 200mL, a total of 1.628g of VFA is produced, resulting in 0.509g of VFA per gram of dry food waste. For every 200mL of 4g / L (0.8g) of VFA consumed, the dry weights of *Chlorella vulgaris* and *Haematococcus pluvialis* cultivated are 1.733g and 1.067g, respectively, corresponding to high-value product yields of 0.5905g biodiesel, 0.2510g amino acids, and 0.0198g astaxanthin. Each gram of VFA is converted into 0.7381g biodiesel, 0.3137g amino acids, and 0.0247g astaxanthin. Each gram of dry food waste is converted into 0.3757g biodiesel, 0.1596g amino acids, or 0.0126g astaxanthin.

[0070] The dry weight of two algae was calculated using algal cell calibration curves. The standard curve equation is as follows, where x is the OD680 absorbance value of the algal solution and Y is the number of algal cells per milliliter. Chlorella calibration curve: y = 0.9228x - 0.0144 Dry weight per 10^7 cells (g): 0.0102624601200034 The gradation line for Haematococcus pluvialis is: y = 1.0614x - 0.0251 Dry weight per 10^7 cells (g): 0.0056245574176382 Analysis of high-value product yields showed that the biodiesel and amino acid contents produced by *Chlorella vulgaris* were 34.07 g / 100g and 14.48 g / 100g, respectively, representing 116.12% and 132.20% of the yields produced under BG-11 culture. The astaxanthin content produced by *Haematococcus pluvialis* was 18.55 mg / g, reaching 124.69% of the BG-11 control group. One g of dry food waste can be converted into 0.3757 g of biodiesel, 0.1596 g of amino acids, or 0.0126 g of astaxanthin, achieving the goal of high-value conversion of food waste.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A three-compartment bioelectrochemical system, characterized in that, It includes an anode chamber (103), an intermediate chamber (105) and a cathode chamber (108). An anode (104) is disposed in the anode chamber (103), and a cathode (107) is disposed in the cathode chamber (108). The anode (104) and the cathode (107) are connected to an external power supply (101) through an alligator clamp. A resistor (102) is connected in series in the circuit. The anode chamber (103) and the intermediate chamber (105) are separated by a cation exchange membrane (110), and the intermediate chamber (105) and the cathode chamber (108) are separated by an anion exchange membrane (111).

2. The three-compartment bioelectrochemical system as described in claim 1, characterized in that, The anode chamber (103), intermediate chamber (105) and cathode chamber (108) are composed of three plexiglass modules, and the plexiglass modules, cation exchange membrane (110) and anion exchange membrane (111) are connected in series by four threaded rods.

3. The three-compartment bioelectrochemical system as described in claim 1, characterized in that, The anode (104) is a titanium electrode mesh coated with IrO2, and the cathode (107) is a titanium mesh.

4. The three-compartment bioelectrochemical system as described in claim 1, characterized in that, Silicone gaskets (106) are provided on both sides of the cation exchange membrane (110) and the anion exchange membrane (111).

5. The three-compartment bioelectrochemical system as described in claim 1, characterized in that, Magnetic stirrers (109) are provided in the anode chamber (103), intermediate chamber (105) and cathode chamber (108).

6. A method for synergistically utilizing microalgae with a three-chamber bioelectrochemical system according to any one of claims 1-5, using forward osmosis-assisted microalgae to extract high-value food waste, characterized in that... Includes the following steps: S1. After washing and stirring the kitchen waste, inoculate it with anaerobic sludge and dilute it to obtain a mixture. Then, adjust the solids content and pH value and ferment it to obtain the fermented product. S2. Centrifuge the fermentation product obtained in step S1, take the supernatant, adjust the pH value, and then add it to the cathode chamber and anode chamber respectively. Then add the trace element supplement to the intermediate chamber to start the operation and obtain the kitchen waste fermentation liquid. S3. Using the fermented liquid of kitchen waste obtained in step S2 as the feed liquid and sodium chloride solution as the absorbent liquid, the liquid is concentrated through a forward osmosis module to obtain concentrated liquid. S4. Dilute the concentrated solution obtained in step S3, inoculate Chlorella and Haematococcus pluvialis solutions respectively, and then culture them. Centrifuge the algal solutions, take the algal mud, dissolve it with sodium acetate, and induce it. Chlorella produces biodiesel and amino acids, while Haematococcus pluvialis produces astaxanthin.

7. The method as described in claim 6, characterized in that, In step S1, the kitchen waste includes 30-40 portions of staple starch, 40-50 portions of vegetables, and 15-25 portions of protein.

8. The method as described in claim 6, characterized in that, In step S1, the pH value is adjusted to 11 and allowed to stand in an anaerobic environment for 24 h. Then, the pH value is adjusted to 5 and anaerobic fermentation is carried out at 35℃ for 5 days. During this period, the pH value of the system is corrected every 12 h.

9. The method as described in claim 6, characterized in that, In step S2, the trace element supplement is BG-11 culture medium that does not contain carbon, nitrogen, or phosphorus elements.

10. The method as described in claim 6, characterized in that, In step S3, the forward osmosis module includes: a feed bottle (207), a draw bottle (210), and two acrylic glass component modules (205). A forward osmosis membrane (202) is disposed between the two acrylic glass component modules (205). Silicone gaskets (209) are disposed between the two sides of the forward osmosis membrane (202) and the acrylic glass component modules (205). The first inlet and outlet water interface (208) of the acrylic glass component module (205) is connected to peristaltic pump one (201) and peristaltic pump two (203) through a rubber tube. A feed inlet (206) is provided on the draw bottle (210).

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