Photobiological cycle fixed bed reaction system and method for purifying urine based on microalgae

Abstract

The present application belongs to the technical field of domestic sewage treatment, and particularly relates to a photobiological circulating fixed bed reaction system and method for purifying urine based on microalgae, which comprises a circulating fixed bed reactor, an illumination system, an aeration system and a liquid driving system; and utilizes clinoptilolite as the filler of the fixed bed zone, so that the concentration of ammonia nitrogen in the urine can be greatly reduced in the circulating adsorption process, thereby providing a favorable environment for the growth of microalgae; the concentration of ammonia nitrogen in the treated urine is reduced to a very low level; under the action of the concentration gradient pressure, the clinoptilolite filler loaded with ammonia nitrogen can desorb ammonia nitrogen into the urine, thereby providing a nitrogen source for the growth of microalgae, and at the same time, the regeneration of the clinoptilolite filler is also achieved.

Description

Technical Field

[0001] This invention belongs to the field of domestic sewage treatment technology, specifically a photobiological circulating fixed-bed reaction system and method for purifying urine based on microalgae. Background Technology

[0002] Urine, a liquid metabolic waste product excreted by the human body, provides a significant amount of nitrogen and phosphorus from urban sewage, despite its relatively small volume. Current methods for recovering nitrogen and phosphorus from urine mainly include evaporation, ammonia stripping, membrane separation, and struvite precipitation. These methods all have limitations, such as high energy consumption, reliance on chemical reagents, and high equipment investment. Microalgae, a type of microorganism containing chlorophyll and capable of photosynthesis, are characterized by their diverse species, high carbon fixation capacity, and strong adaptability. Utilizing microalgae to treat urine can achieve highly efficient recovery of nitrogen and phosphorus, offering advantages such as low operating costs, no secondary pollution, and low carbon emissions. The harvested microalgae biomass can be processed into high-value products such as biofuels, aquaculture feed, and health supplements, thus providing further economic benefits.

[0003] However, the aforementioned technologies often have the following drawbacks: there are still certain obstacles to using microalgae to treat urine. First, the high concentration of ammonia nitrogen in hydrolyzed urine inhibits the growth of microalgae, mainly in terms of genetic information, photosynthesis, and nutrient metabolism pathways, slowing down the growth rate of microalgae and even causing them to die. Traditional urine pretreatment methods mainly include dilution and nitrification, which means that a large amount of water resources are required and additional treatment units are needed, increasing the system operating cost. Second, the photobioreactor is the core device for microalgae cultivation, but the color of urine and the high biomass in the later stages of cultivation reduce the light energy received by microalgae inside the reactor, which prevents the microalgae biomass from being further increased in the later stages of cultivation. Therefore, in the application of microalgae to treat urine on a large scale, there are problems such as high concentration of ammonia nitrogen inhibition and poor light absorption capacity of microalgae in the photobioreactor. To address these issues, this invention provides a photobioreactor circulating fixed-bed reaction system and method for purifying urine using microalgae. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0005] The technical solution adopted by the present invention to solve its technical problem is: the photobiological circulating fixed bed reaction system based on microalgae to purify urine according to the present invention includes a circulating fixed bed reactor, a lighting system, an aeration system and a liquid driving system;

[0006] The circulating fixed bed reactor includes an outer cylinder and an inner cylinder, both of which are transparent hollow structures with the same height. The inner cylinder is coaxially fixed inside the outer cylinder.

[0007] A reactor bottom plate is disposed at the bottom of the outer cylinder and the inner cylinder of the reactor.

[0008] A reactor top cover is disposed at the top of the outer cylinder and the inner cylinder of the reactor.

[0009] The first, second, third, and fourth baffles are all made of transparent material and are at the same height as the outer and inner cylinders of the reactor. They are vertically arranged in the space between the outer and inner cylinders of the reactor, dividing the space into four equal-volume chambers: an inflow zone, a first aeration zone, a second aeration zone, and an outflow zone. The first, second, and third baffles are provided with circular holes to ensure the flow of reactants between the chambers.

[0010] Clinoptilolite packing material is used to fill the interior of the inner cylinder of the reactor, which is called the fixed bed zone. The particle size of the clinoptilolite packing material is 1-3 mm, and the filling volume accounts for 80-90% of the volume of the fixed bed zone.

[0011] The inner cylinder of the reactor is cut off at the upper part of the inflow zone to ensure water overflow. The upper interface of the cut-off is flush with the height of the inner cylinder of the reactor, and the lower interface of the cut-off is higher than the height of the fixed bed zone.

[0012] The first baffle hole is located at the bottom, the second baffle hole is located at the top and the upper limit of the hole is not higher than the lower interface of the inner cylinder of the reactor, and the third baffle hole is located at the bottom.

[0013] An inlet is located on the top cover of the reactor and is used to inject the reactants and inoculate the microalgae;

[0014] An exhaust valve, located on the top cover of the reactor, is used to discharge excess gas from the circulating fixed bed reactor.

[0015] A drain outlet is located at the bottom of the outer cylinder of the reactor to drain the reactants in the circulating fixed bed reactor.

[0016] The reactor base is located below the reactor bottom plate and is used to support the main body of the circulating fixed bed reactor.

[0017] Preferably, the lighting system includes an arc-shaped light guide plate, which is disposed outside the circulating fixed bed reactor to provide light to the cultured microalgae;

[0018] LED light strips are attached to the thick surface above the curved light guide plate, and provide blue light in the spectrum.

[0019] The arc-shaped light guide plate with its arc surface closer to the circulating fixed bed reactor serves as the light emission surface, while the arc surface farther from the circulating fixed bed reactor and other thickness surfaces are covered with reflective film as reflective surfaces.

[0020] Preferably, the aeration system includes an aerator that provides an air-mixed gas to the circulating fixed bed reactor;

[0021] A gas delivery main pipe, connected to the aerator, is used to deliver the air-gas mixture;

[0022] A manual on / off valve for the gas pipeline is installed on the gas delivery main pipeline to control the delivery of the air-mixed gas.

[0023] A gas delivery branch pipe passes through the top cover of the reactor and extends into the first aeration zone and the second aeration zone of the circulating fixed bed reactor;

[0024] A gas tee connector is connected to the gas delivery main pipe and the gas delivery branch pipe;

[0025] A gas flow meter is installed on the gas delivery branch pipe to control the aeration flow rate;

[0026] A microporous aerator head is installed at the end of the gas delivery branch pipe to generate microporous bubbles.

[0027] Preferably, the liquid-driven system includes a peristaltic pump that provides a power source for the circulation of the reactants;

[0028] Outflow branch pipe, inflow branch pipe, connected to peristaltic pump;

[0029] The liquid transport branch pipe in the fixed bed area is used to transfer the reactants in the fixed bed area, passes through the top cover of the reactor, and extends to the bottom of the fixed bed area;

[0030] The liquid delivery branch pipe in the outflow zone is used to transfer the reactants in the outflow zone, passes through the top cover of the reactor, and extends to the bottom of the outflow zone;

[0031] The inflow zone liquid delivery branch pipe, used to transfer the reactants in the inflow zone, passes through the top cover of the reactor and extends to the bottom of the inflow zone;

[0032] A quick-connect water pipe is installed at the top of the liquid delivery branch pipe in the fixed bed area, the liquid delivery branch pipe in the outflow area, and the liquid delivery branch pipe in the inflow area to achieve connection with the outflow branch pipe and the inflow branch pipe;

[0033] Manual on / off valves for water pipes are installed on the liquid delivery branch pipes of the fixed bed area, the liquid delivery branch pipes of the outflow area, and the liquid delivery branch pipes of the inflow area to control the delivery of the reactants.

[0034] Preferably, the microporous aeration head has an annular groove on its sidewall, a slider is slidably connected to the inner wall of the annular groove, a connecting plate is fixedly connected to the side of the slider away from the annular groove, a brush for cleaning the micropores is fixedly connected to the side of the connecting plate near the microporous aeration head, a rotatable connecting shaft is vertically arranged inside the microporous aeration head, a set of drive blades is fixedly connected to the sidewall of the connecting shaft, a fixing rod is fixedly connected to the sidewall of the micropore corresponding to the connecting shaft, and a first magnetic block that magnetically attracts the connecting plate is fixedly connected to the side of the fixing rod away from the connecting shaft.

[0035] Preferably, the microporous aerator head is slidably and sealed to the side wall of the gas delivery branch pipe, a pair of connecting rods are fixedly connected to the bottom surface of the gas delivery branch pipe, a disc is fixedly connected to the bottom surface of the connecting rods, the top surface of the connecting shaft is rotatably connected to the disc, a ring is slidably connected to the side wall of the disc, a set of first springs is fixedly connected between the top surface of the ring and the inner wall of the top surface of the microporous aerator head, a second magnetic block is fixedly connected to the top surface of the drive blade, and a set of magnetic sheets corresponding to the second magnetic block is fixedly connected to the bottom surface of the disc, with the second magnetic block and the magnetic sheets being arranged in a repulsive manner.

[0036] Preferably, the microporous aerator head has a hollow groove, and a sealing plate for sealing the micropores is slidably connected inside the hollow groove. The sealing plate has through holes corresponding to the micropores. The inner wall of the microporous aerator head has an air inlet hole communicating with the hollow groove, and the air inlet hole is located on the bottom surface of the sealing plate. The outer wall of the microporous aerator head has an air outlet hole communicating with the hollow groove, and the air outlet hole is located on the top surface of the sealing plate. A second spring is fixedly connected between the top surface of the sealing plate and the inner wall of the hollow groove.

[0037] The photobiological circulating fixed-bed reaction method for purifying urine based on microalgae, which employs the aforementioned photobiological circulating fixed-bed reaction system for purifying urine based on microalgae, includes the following steps:

[0038] S1: Introduce urine into the circulating fixed bed reactor through the inlet, connect the outflow branch to the liquid delivery branch of the fixed bed area, connect the inflow branch to the liquid delivery branch of the outflow area, start the peristaltic pump, and the urine circulates and adsorbs in the circulating fixed bed reactor until saturation, then turn off the peristaltic pump.

[0039] S2: Connect the outflow branch to the inflow zone liquid delivery branch and the inflow branch to the fixed bed zone liquid delivery branch. Turn on the peristaltic pump to drain the residual urine from the fixed bed zone into the inflow zone, and then turn off the peristaltic pump.

[0040] S3: Inoculate microalgae into the circulating fixed bed reactor through the inlet, connect the outflow branch pipe to the inflow liquid transport branch pipe, connect the inflow branch pipe to the outflow liquid transport branch pipe, and turn on the aerator and peristaltic pump to circulate and cultivate microalgae.

[0041] S4: The daytime and nighttime lighting effects are distinguished by turning the LED light strip on and off. The daytime and nighttime durations are 14 hours and 10 hours respectively, and this cycle continues continuously. When the microalgae growth reaches a stable state, the aerator and peristaltic pump are turned off.

[0042] S5: The urine and microalgae mixture is discharged through the drain outlet. After algae-water separation, the separated urine is collected and introduced into the circulating fixed bed reactor through the inlet. Microalgae are then inoculated through the inlet.

[0043] S6: During the day, connect the outflow branch pipe to the inflow liquid transport branch pipe and the inflow branch pipe to the outflow liquid transport branch pipe, turn on the aerator and peristaltic pump, and carry out suspension culture of microalgae.

[0044] S7: At night, turn off the aerator and peristaltic pump, connect the outflow branch to the liquid delivery branch of the fixed bed area, connect the inflow branch to the liquid delivery branch of the outflow area, and then turn on the peristaltic pump to regenerate the clinoptilolite packing material using a mixture of urine and microalgae, while realizing the zeolite-based microalgae circulation culture.

[0045] S8: The lighting effect is distinguished by turning the LED light strip on and off. The daytime and nighttime durations are 14 hours and 10 hours respectively. This cycle continues continuously. When the microalgae growth reaches a stable state, the process ends, the aerator and peristaltic pump are turned off, and the urine and microalgae mixture is discharged from the drain outlet for algae-water separation.

[0046] The beneficial effects of this invention are as follows:

[0047] 1. The present invention addresses the inhibitory effect of high concentrations of ammonia nitrogen in urine on microalgae growth. Clinoptilolite is an aluminosilicate mineral with high ion exchange capacity and good affinity for ammonium ions. Using clinoptilolite as a packing material in the fixed bed zone can significantly reduce the concentration of ammonia nitrogen in urine during the cyclic adsorption process, thereby providing a favorable environment for microalgae growth. After treatment, the concentration of ammonia nitrogen in urine is reduced to a considerably low level. Under the action of concentration gradient pressure, the ammonia nitrogen-loaded clinoptilolite packing material can desorb ammonia nitrogen into the urine, providing a nitrogen source for microalgae growth. At the same time, this process also realizes the regeneration of the clinoptilolite packing material.

[0048] 2. In this invention, the color of urine and the high biomass concentration of microalgae can obscure the light inside the reactor. By placing the fixed bed area, which does not require light, in the center of the reactor, the impact of insufficient internal irradiation is reduced. In addition, by independently setting up the fixed bed area, it is beneficial to mix and separate the clinoptilolite packing and reactants. An inflow zone, a first aeration zone, a second aeration zone, and an outflow zone are set up outside the fixed bed area. Microalgae are cultivated in these four zones, which shortens the light path and improves photosynthetic efficiency. Furthermore, all functional units are integrated into a single reactor body, which reduces the footprint and the difficulty of operation and management. Moreover, by switching the liquid pipeline, multiple operating modes can be changed, providing great flexibility.

[0049] 3. The light-harvesting pigments of microalgae in this invention are more sensitive to blue light. Blue light has a short wavelength and high energy, and has stronger penetrating power in water. Using an arc-shaped light guide plate that emits blue light as a light source improves the photosynthetic efficiency of microalgae, and is also conducive to the production of microalgae biomass and the accumulation of intracellular components, which is beneficial to the subsequent development of microalgae resources.

[0050] 4. When the gas delivery branch pipe of the present invention injects gas into the microporous aeration head, the airflow drives the drive blade to rotate. At this time, the drive blade will drive the connecting shaft to rotate, thereby driving the first magnetic block to rotate. At this time, the connecting plate magnetically attracted to the first magnetic block will also rotate. At this time, the bristles will unclog and clean the micropores on the microporous aeration head to solve the problem of blockage that will occur after long-term use of the micropores. Attached Figure Description

[0051] The invention will now be further described with reference to the accompanying drawings.

[0052] Figure 1 This is a schematic diagram of the photobiological circulating fixed-bed reaction system in this invention;

[0053] Figure 2 This is a schematic diagram of the circulating fixed-bed reactor in this invention;

[0054] Figure 3 This is a top view of the circulating fixed-bed reactor in this invention;

[0055] Figure 4 This is a schematic diagram of the inflow zone structure of the circulating fixed-bed reactor in this invention;

[0056] Figure 5 This is a schematic diagram of the structure of the first aeration zone of the circulating fixed bed reactor in this invention;

[0057] Figure 6 This is a schematic diagram of the structure of the second aeration zone of the circulating fixed bed reactor in this invention;

[0058] Figure 7 This is a schematic diagram of the effluent zone of the circulating fixed-bed reactor in this invention;

[0059] Figure 8 This is a schematic diagram of the structure of the fixed bed region in the circulating fixed bed reactor of this invention;

[0060] Figure 9 This is a schematic diagram of the structure of the gas delivery branch pipe and the microporous aeration head in this invention;

[0061] Figure 10 This is a schematic diagram of the internal structure of the microporous aeration head in this invention;

[0062] Figure 11 yes Figure 10 Enlarged view of point A;

[0063] Figure 12 yes Figure 10 Enlarged view of point B;

[0064] Figure 13 This is a flowchart of the method in this invention.

[0065] In the diagram: 1. Aerator; 2. Gas delivery main pipe; 3. Manual gas pipe switch valve; 4. Gas tee connector; 5. Gas flow meter; 6. Gas delivery branch pipe; 7. Microporous aerator head; 8. First baffle; 9. Second baffle; 10. Third baffle; 11. Fourth baffle; 12. Reactor top cover; 13. Reactor outer cylinder; 14. Reactor inner cylinder; 15. Cyanide zeolite packing; 16. Inlet; 17. Exhaust valve; 18. Drain; 19. Reactor base; 20. Reactor bottom plate; 21. Peristaltic pump; 22. 23. Outflow branch pipe; 24. Inflow branch pipe; 25. Quick-connect water pipe; 26. Manual water pipe valve; 27. Liquid delivery branch pipe in the fixed bed area; 28. Liquid delivery branch pipe in the outflow area; 29. ​​Arc-shaped light guide plate; 30. LED light strip; 31. Connecting shaft; 32. Drive blade; 33. Fixed rod; 34. First magnetic block; 35. Connecting plate; 36. Connecting rod; 37. Disc; 38. Ring; 39. Magnetic sheet; 40. Second magnetic block; 41. Hollow groove; 42. Sealing plate; 43. Slider. Detailed Implementation

[0066] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0067] Example 1: As Figures 1 to 8 As shown in the embodiment of the present invention, the photobiological circulating fixed-bed reaction system for purifying urine based on microalgae consists of a circulating fixed-bed reactor, a lighting system, an aeration system, and a liquid-driven system.

[0068] The circulating fixed-bed reactor includes an outer cylinder 13 and an inner cylinder 14, both of which are transparent hollow structures. The inner cylinder 14 is coaxially fixed inside the outer cylinder 13. A reactor bottom plate 20 is disposed at the bottom of the outer cylinder 13 and the inner cylinder 14. A reactor top cover 12 is disposed at the top of the outer cylinder 13 and the inner cylinder 14. A first baffle 8, a second baffle 9, a third baffle 10, and a fourth baffle 11 are vertically disposed in the space between the outer cylinder 13 and the inner cylinder 14, dividing the space into four equal-volume chambers: an inflow zone, a first aeration zone, a second aeration zone, and an outflow zone. Clinoptilolite packing 15 is filled inside the inner cylinder 14, which is called the fixed-bed zone.

[0069] The outer cylinder 13 of the reactor has a diameter of 120 mm, the inner cylinder 14 of the reactor has a diameter of 60 mm, and the height of both the outer cylinder 13 and the inner cylinder 14 is set to 160 mm. The inner cylinder 14 has a cut-off at the top of the inflow area to ensure overflow of the effluent, and the cut-off height is set to 10 mm.

[0070] The height of the first baffle 8, the second baffle 9, the third baffle 10, and the fourth baffle 11 is set to 160mm, as per the instruction manual. Figure 4 , 5 As shown in Figure 6, circular holes are provided in the first baffle 8, the second baffle 9, and the third baffle 10 to ensure the flow of reactants between the chambers. The holes in the first baffle 8 are located at the bottom of the baffle, the holes in the second baffle 9 are located at the top of the baffle and the upper limit of the holes is not higher than the lower interface of the inner cylinder of the reactor, and the holes in the third baffle 10 are located at the bottom of the baffle with a diameter of 10 mm.

[0071] The outer cylinder 13, inner cylinder 14, bottom plate 20, top cover 12, first baffle 8, second baffle 9, third baffle 10, and fourth baffle 11 of the reactor are all made of polymethyl methacrylate.

[0072] The particle size of the clinoptilolite packing 15 is 1-3 mm, and the packing volume accounts for 80% of the volume of the fixed bed area.

[0073] The circulating fixed bed reactor also includes an inlet 16, located on the reactor top cover 12, for injecting reactants and inoculating microalgae; an exhaust valve 17, located on the reactor top cover 12, for discharging excess gas from the circulating fixed bed reactor; an outlet 18, located at the bottom of the reactor outer cylinder 13, for emptying the reactants from the circulating fixed bed reactor; and a reactor base 19, located below the reactor bottom plate 20, for supporting the main body of the circulating fixed bed reactor.

[0074] The lighting system consists of two curved light guide plates 29 and LED light strips 30. The two curved light guide plates 29 are located outside the circulating fixed bed reactor. The LED light strips 30 are attached to the thick surface above the curved light guide plates 29. The curved surface of the curved light guide plates 29 that is closer to the circulating fixed bed reactor serves as the light emitting surface, while the curved surface that is farther from the circulating fixed bed reactor and other thick surfaces are attached with reflective films as reflective surfaces. The spectral color provided by the LED light strips 30 is blue light (450-485nm).

[0075] The aeration system consists of an aerator 1, a gas delivery main pipe 2, a manual gas pipe switch valve 3, a gas tee connector 4, a gas flow meter 5, a gas delivery branch pipe 6, and a microporous aeration head 7. The aerator 1 provides an air-to-gas mixture (CO2 volume fraction of 5%). The output air-to-gas mixture enters the gas tee connector 4 along the gas delivery main pipe 2 and then connects to two gas delivery branch pipes 6. The two gas delivery branch pipes 6 pass through the reactor top cover 12 and are respectively connected to the first aeration zone and the second aeration zone of the circulating fixed bed reactor. Microporous aeration heads 7 are connected to the ends of the two gas delivery branch pipes 6 to provide microporous bubbles. The manual gas pipe switch valve 3 is set on the gas delivery main pipe 2 to control the delivery of the air-to-gas mixture. Two gas flow meters 5 are respectively set on the gas delivery branch pipes 6 to control the flow rate of the delivered air-to-gas mixture. The aeration flow rate is set to 0.1 VVM.

[0076] The liquid-driven system consists of a peristaltic pump 21, an outflow branch pipe 22, an inflow branch pipe 23, a quick-connect water pipe 24, a manual water pipe valve 25, a liquid delivery branch pipe 26 for the fixed bed zone, a liquid delivery branch pipe 27 for the outflow zone, and a liquid delivery branch pipe 28 for the inflow zone. The peristaltic pump 21 is connected to the outflow branch pipe 22 and the inflow branch pipe 23, providing power for reactant circulation. The liquid delivery branch pipe 26 for the fixed bed zone is used to transfer reactants within the fixed bed zone, passing through the reactor top cover 12 and extending to the bottom of the fixed bed zone. The liquid delivery branch pipe 27 for the outflow zone is used to transfer reactants within the outflow zone, passing through... The reactor top cover 12 extends to the bottom of the outflow zone; the inflow zone liquid transport branch pipe 28, used to transfer reactants in the inflow zone, passes through the reactor top cover 12 and extends to the bottom of the inflow zone; the water pipe manual switch valve 25 is set on the fixed bed zone liquid transport branch pipe 26, the outflow zone liquid transport branch pipe 27 and the inflow zone liquid transport branch pipe 28 to control the transport of reactants; the water pipe quick connector 24 is set at the top of the fixed bed zone liquid transport branch pipe 26, the outflow zone liquid transport branch pipe 27 and the inflow zone liquid transport branch pipe 28 to realize the connection with the outflow branch pipe 22 and the inflow branch pipe 23.

[0077] The photobiological circulating fixed-bed reaction system in Example 1 uses clinoptilolite packing 15 as the packing material in the fixed bed zone. During the circulating adsorption process, it can greatly reduce the concentration of ammonia nitrogen in urine, thereby providing a favorable environment for the growth of microalgae. In addition, the clinoptilolite packing 15 loaded with ammonia nitrogen can continuously release ammonia nitrogen into urine with low ammonia nitrogen concentration under the action of concentration gradient pressure, providing a nitrogen source for the growth of microalgae. At the same time, this process also realizes the regeneration of clinoptilolite packing 15.

[0078] The photobiological circulating fixed-bed reaction system in Example 1 places the fixed-bed area, which does not require light, in the center of the reactor, thereby reducing the impact of insufficient internal irradiation. In addition, by setting up the fixed-bed area independently, it is beneficial to mix and separate the clinoptilolite packing 15 with the reactants. An inflow zone, a first aeration zone, a second aeration zone, and an outflow zone are set outside the fixed-bed area. Microalgae are cultivated in the above four zones, which shortens the light path and improves the photosynthetic efficiency. Furthermore, all functional units are integrated into a single reactor body, which reduces the footprint and the difficulty of operation and management. Moreover, by switching the liquid pipeline, multiple operating modes can be changed, which has great flexibility.

[0079] The photobio-circulating fixed-bed reaction system in Example 1 uses an arc-shaped light guide plate 29 that emits blue light as a light source to improve the photosynthetic efficiency of microalgae, while also contributing to the production of microalgae biomass and the accumulation of intracellular components, which is beneficial for the subsequent development of microalgae resources.

[0080] Example 2: Figures 9 to 12 As shown in the comparative embodiment one, another embodiment of the present invention is as follows: The sidewall of the microporous aeration head 7 has an annular groove. A slider 43 is slidably connected to the inner wall of the annular groove. A connecting plate 35 is fixedly connected to the side of the slider 43 away from the annular groove. A brush for cleaning the micropores is fixedly connected to the side of the connecting plate 35 near the microporous aeration head 7. A rotatable connecting shaft 31 is vertically arranged inside the microporous aeration head 7. A set of driving blades 32 is fixedly connected to the sidewall of the connecting shaft 31. A fixing rod 33 is fixedly connected to the sidewall of the connecting shaft 31 corresponding to the micropore. The fixing rod 33 is located away from the connecting shaft 31. A first magnetic block 34, which is magnetically attracted to the connecting plate 35, is fixedly connected to one side. Given that the micropores of the micropore aerator head 7 may become clogged due to impurities in the gas during long-term use, this application utilizes the aforementioned mechanism to allow the airflow to drive the drive blade 32 to rotate when gas is injected into the micropore aerator head 7 via the gas delivery branch pipe 6. This drive blade 32 then rotates the connecting shaft 31, thereby rotating the first magnetic block 34. The connecting plate 35, which is magnetically attracted to the first magnetic block 34, also rotates. At this time, the brush bristles unclog and clean the micropores on the micropore aerator head 7, thus solving the problem of clogging that occurs after prolonged use.

[0081] The microporous aeration head 7 is slidably and sealed to the side wall of the gas delivery branch pipe 6. A pair of connecting rods 36 are fixedly connected to the bottom surface of the gas delivery branch pipe 6. A disc 37 is fixedly connected to the bottom surface of the connecting rods 36. The top surface of the connecting shaft 31 is rotatably connected to the disc 37. A ring 38 is slidably connected to the side wall of the disc 37. A set of first springs is fixedly connected between the top surface of the ring 38 and the inner wall of the top surface of the microporous aeration head 7. A second magnetic block 40 is fixedly connected to the top surface of the drive blade 32. A set of magnetic sheets 39 corresponding to the second magnetic block 40 is fixedly connected to the bottom surface of the disc 37. The second magnetic block 40 and the magnetic sheets 39 are arranged in a repulsive manner. In this application, when the drive blade 32 rotates, the second magnetic block 40 will intermittently pass through the magnetic sheets 39, so that the second magnetic block 40 can intermittently push. When the magnetic plate 39 is pushed, the ring 38 pushes the first spring, which in turn provides thrust to the microporous aerator head 7, causing it to move upward. When the second magnetic block 40 moves away from the magnetic plate 39, the microporous aerator head 7 moves downward due to its weight. This causes the microporous aerator head 7 to vibrate. During this vibration, the distribution of bubbles generated at the micropores changes, altering the size and number of bubbles. Smaller bubbles provide a larger specific surface area, thus improving oxygen transfer efficiency and making the bubble distribution in the liquid more uniform. This allows oxygen to dissolve more fully into the liquid, improving the aeration effect. Simultaneously, the vibration of the microporous aerator head 7 disturbs the liquid flow, increasing the mixing of the liquid and improving the efficiency of liquid treatment.

[0082] The microporous aerator head 7 has a hollow groove 41. A sealing plate 42, which seals the micropores, is slidably connected within the hollow groove 41. The sealing plate 42 has through holes corresponding to the micropores. An air inlet hole communicating with the hollow groove 41 is located on the inner wall of the microporous aerator head 7, and is situated on the bottom surface of the sealing plate 42. An air outlet hole communicating with the hollow groove 41 is located on the outer wall of the microporous aerator head 7, and is situated on the top surface of the sealing plate 42. A second spring is fixedly connected between the top surface of the sealing plate 42 and the inner wall of the hollow groove 41. The gas in this application... When injected into the microporous aerator head 7, the gas first enters the hollow groove 41 through the air inlet and pushes the sealing plate 42. At this time, the sealing plate 42 moves upward, thereby aligning the through hole with the micro hole. The gas continuously injected into the microporous aerator head 7 can be evenly discharged from the micro hole, so that the bubbles can be generated evenly, thereby improving the uniformity of the bubbles. At the same time, when the microporous aerator head 7 shakes, the sealing plate 42 will also shake slightly. At this time, the through hole and the micro hole will be misaligned, reducing the pore size of the micro hole, thereby allowing the gas discharged from the micro hole to generate more and smaller bubbles.

[0083] like Figure 13As shown, a photobiological circulating fixed-bed reaction method for purifying urine based on microalgae is described above. This method employs the aforementioned photobiological circulating fixed-bed reaction system for purifying urine based on microalgae and includes the following steps:

[0084] S1: Introduce urine into the circulating fixed bed reactor through the inlet, connect the outflow branch to the liquid delivery branch of the fixed bed area, connect the inflow branch to the liquid delivery branch of the outflow area, start the peristaltic pump, and the urine circulates and adsorbs in the circulating fixed bed reactor until saturation, then turn off the peristaltic pump.

[0085] S2: Connect the outflow branch to the inflow zone liquid delivery branch and the inflow branch to the fixed bed zone liquid delivery branch. Turn on the peristaltic pump to drain the residual urine from the fixed bed zone into the inflow zone, and then turn off the peristaltic pump.

[0086] S3: Inoculate microalgae into the circulating fixed bed reactor through the inlet, connect the outflow branch pipe to the inflow liquid transport branch pipe, connect the inflow branch pipe to the outflow liquid transport branch pipe, and turn on the aerator and peristaltic pump to circulate and cultivate microalgae.

[0087] S4: The daytime and nighttime lighting effects are distinguished by turning the LED light strip on and off. The daytime and nighttime durations are 14 hours and 10 hours respectively, and this cycle continues continuously. When the microalgae growth reaches a stable state, the aerator and peristaltic pump are turned off.

[0088] S5: The urine and microalgae mixture is discharged through the drain outlet. After algae-water separation, the separated urine is collected and introduced into the circulating fixed bed reactor through the inlet. Microalgae are then inoculated through the inlet.

[0089] S6: During the day, connect the outflow branch pipe to the inflow liquid transport branch pipe and the inflow branch pipe to the outflow liquid transport branch pipe, turn on the aerator and peristaltic pump, and carry out suspension culture of microalgae.

[0090] S7: At night, turn off the aerator and peristaltic pump, connect the outflow branch to the liquid delivery branch of the fixed bed area, connect the inflow branch to the liquid delivery branch of the outflow area, and then turn on the peristaltic pump to regenerate the clinoptilolite packing material using a mixture of urine and microalgae, while realizing the zeolite-based microalgae circulation culture.

[0091] S8: The lighting effect is distinguished by turning the LED light strip on and off. The daytime and nighttime durations are 14 hours and 10 hours respectively. This cycle continues continuously. When the microalgae growth reaches a stable state, the process ends, the aerator and peristaltic pump are turned off, and the urine and microalgae mixture is discharged from the drain outlet for algae-water separation.

[0092] Working principle: 1L of urine is introduced into the circulating fixed bed reactor through inlet 16. Outlet branch pipe 22 is connected to liquid delivery branch pipe 26 in the fixed bed area, and inlet branch pipe 23 is connected to liquid delivery branch pipe 27 in the outlet area. Peristaltic pump 21 is started at a flow rate of 60ml / min. Urine is introduced to the bottom of the fixed bed area and flows from the bottom to the top, forming an overflow. It enters the inlet area, the first aeration area, the second aeration area and the outlet area in sequence. Finally, it is introduced into the fixed bed area from the outlet area through peristaltic pump 21. This process is continuously circulated until adsorption saturation. This step is run for 2 days, and then peristaltic pump 21 is turned off.

[0093] Connect the outflow branch pipe 22 to the inflow liquid delivery branch pipe 28, and the inflow branch pipe 23 to the fixed bed liquid delivery branch pipe 26. Turn on the peristaltic pump 21 at a flow rate of 100 ml / min to discharge residual urine from the fixed bed into the inflow area. Then turn off the peristaltic pump 21. Inoculate the circulating fixed bed reactor with Chlorella proteoglycans through the inlet 16. Connect the outflow branch pipe 22 to the inflow liquid delivery branch pipe 28, and the inflow branch pipe 23 to the outflow liquid delivery branch pipe 27. Turn on the aerator 1 and the peristaltic pump 21. The aeration gas source is an air mixture (CO2 volume fraction of 5%), and the aeration flow rate is 0.1 VVM. The peristaltic pump 21 has a flow rate of 60 ml / min. At this time, the circulation sequence of the urine and Chlorella proteinensis mixture is the inflow zone, the first aeration zone, the second aeration zone, and the outflow zone. The lighting effect of day and night is distinguished by turning the LED light strip 30 on and off. The day and night time are 14 hours and 10 hours respectively. This cycle is repeated continuously. This step is run for 15 days. Then the growth of Chlorella proteinensis reaches stability. Finally, the aerator 1 and peristaltic pump 21 are turned off.

[0094] The urine and Chlorella proteoglycans mixture is discharged through drain outlet 18. After algae-water separation, the separated urine is collected and introduced into the circulating fixed bed reactor through inlet 16. Chlorella proteoglycans are then inoculated through inlet 16. During the day, the outflow branch pipe 22 is connected to the inflow liquid delivery branch pipe 28, and the inflow branch pipe 23 is connected to the outflow liquid delivery branch pipe 27. Aerator 1 and peristaltic pump 21 are turned on. The aeration gas source is air mixture (CO2 volume fraction of 5%), the aeration gas flow rate is 0.1 VVM, and the peristaltic pump 21 flow rate is 60 ml / min. The units participating in the circulation are the inflow zone, the first aeration zone, the second aeration zone, and the outflow zone. At night, aerator 1 and peristaltic pump 21 are turned off. Outflow branch pipe 22 is connected to liquid delivery branch pipe 26 in the fixed bed area, and inflow branch pipe 23 is connected to liquid delivery branch pipe 27 in the outflow area. Then, peristaltic pump 21 is turned on at a flow rate of 60 ml / min. At this time, the units participating in the circulation are the inflow area, the first aeration area, the second aeration area, the outflow area, and the fixed bed area. The lighting effect of day and night is distinguished by turning LED light strip 30 on and off. The day and night time are 14 hours and 10 hours respectively. This cycle is repeated continuously. This step is run for 13 days. At this time, the growth of Chlorella proteoglycans reaches stability. Aerator 1 and peristaltic pump 21 are turned off. Urine and Chlorella proteoglycans mixture is discharged from drain outlet 18 for algae-water separation.

[0095] The terms "front," "back," "left," "right," "top," and "bottom" all refer to the figures in the accompanying drawings. Figure 1 Based on the perspective of the observer, the side of the device facing the observer is defined as the front, the left side of the observer is defined as the left, and so on.

[0096] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0097] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A photobiological circulating fixed-bed reaction system for purifying urine based on microalgae, comprising a circulating fixed-bed reactor, a lighting system, an aeration system, and a liquid-driven system; Its features are: The circulating fixed bed reactor includes an outer cylinder (13) and an inner cylinder (14), both of which are transparent hollow structures with the same height. The inner cylinder (14) is coaxially fixed inside the outer cylinder (13). The reactor bottom plate (20) is located at the bottom of the outer cylinder (13) and the inner cylinder (14) of the reactor; The reactor top cover (12) is disposed on the top of the outer cylinder (13) and the inner cylinder (14) of the reactor; The first baffle (8), the second baffle (9), the third baffle (10), and the fourth baffle (11) are all made of transparent material and are at the same height as the outer cylinder (13) and the inner cylinder (14) of the reactor. They are vertically arranged in the space between the outer cylinder (13) and the inner cylinder (14) of the reactor, dividing the space into four chambers of equal volume, namely the inflow zone, the first aeration zone, the second aeration zone, and the outflow zone. The first baffle (8), the second baffle (9), and the third baffle (10) are provided with circular holes to ensure the flow of reactants between the chambers. Clinoptilolite packing (15) is filled inside the inner cylinder (14) of the reactor, which is called the fixed bed zone. The particle size of the clinoptilolite packing (15) is 1-3 mm, and the filling volume accounts for 80-90% of the volume of the fixed bed zone. The inner cylinder (14) of the reactor is cut off at the upper part of the inflow area to ensure water overflow. The upper interface of the cut-off is flush with the height of the inner cylinder (14) of the reactor, and the lower interface of the cut-off is higher than the height of the fixed bed area. The first baffle (8) has a hole at the bottom, the second baffle (9) has a hole at the top and the upper limit of the hole is not higher than the lower interface cut off by the inner cylinder (14) of the reactor, and the third baffle (10) has a hole at the bottom. The inlet (16) is located on the top cover (12) of the reactor and is used to inject the reactants and inoculate the microalgae. An exhaust valve (17) is provided on the top cover (12) of the reactor to discharge excess gas in the circulating fixed bed reactor; A drain outlet (18) is provided at the bottom of the outer cylinder (13) of the reactor to drain the reactants in the circulating fixed bed reactor; The reactor base (19) is located below the reactor base plate (20) and is used to support the main body of the circulating fixed bed reactor.

2. The photobiological circulating fixed-bed reaction system for purifying urine based on microalgae according to claim 1, characterized in that: The lighting system includes an arc-shaped light guide plate (29), which is disposed outside the circulating fixed bed reactor and is used to provide light to the cultured microalgae; LED light strip (30) is attached to the upper thickness surface of the arc-shaped light guide plate (29) and provides blue light as the spectral color; The arc-shaped light guide plate (29) has a curved surface closer to the circulating fixed bed reactor as the light emission surface, and a curved surface farther from the circulating fixed bed reactor and other thickness surfaces are attached with reflective film as reflective surfaces.

3. The photobiological circulating fixed-bed reaction system for purifying urine based on microalgae according to claim 2, characterized in that: The aeration system includes an aerator (1) that provides an air-mixed gas to the circulating fixed bed reactor; The gas delivery main pipe (2) is connected to the aerator (1) and is used to deliver the air-mixed gas; A manual gas pipe switch valve (3) is installed on the gas delivery main pipe (2) to control the delivery of the air mixture; The gas delivery branch pipe (6) passes through the reactor top cover (12) and extends into the first aeration zone and the second aeration zone of the circulating fixed bed reactor; Gas tee connector (4) is connected to the gas delivery main pipe (2) and the gas delivery branch pipe (6); A gas flow meter (5) is installed on the gas delivery branch pipe (6) to control the aeration flow rate; The microporous aeration head (7) is located at the end of the gas delivery branch pipe (6) and is used to generate microporous bubbles.

4. The photobiological circulating fixed-bed reaction system for purifying urine based on microalgae according to claim 3, characterized in that: The liquid-driven system includes a peristaltic pump (21) that provides a power source for the circulation of the reactants; Outflow branch pipe (22) and inflow branch pipe (23) are connected to peristaltic pump (21); The liquid transport branch pipe (26) in the fixed bed area is used to transfer the reactants in the fixed bed area, passes through the reactor top cover (12), and extends to the bottom of the fixed bed area; The liquid delivery branch pipe (27) in the outflow zone is used to transfer the reactants in the outflow zone, passes through the top cover of the reactor (12), and extends to the bottom of the outflow zone; The inflow zone liquid delivery branch pipe (28) is used to transfer the reactants in the inflow zone, passes through the reactor top cover (12), and extends to the bottom of the inflow zone; A quick-connect pipe (24) is installed at the top of the liquid transport branch pipe (26) in the fixed bed area, the liquid transport branch pipe (27) in the outflow area, and the liquid transport branch pipe (28) in the inflow area to achieve connection with the outflow branch pipe (22) and the inflow branch pipe (23); A manual on / off valve (25) is installed on the liquid delivery branch pipe (26) of the fixed bed area, the liquid delivery branch pipe (27) of the outflow area, and the liquid delivery branch pipe (28) of the inflow area to control the delivery of the reactants.

5. The photobiological circulating fixed-bed reaction system for purifying urine based on microalgae according to claim 4, characterized in that: The microporous aeration head (7) has an annular groove on its side wall. A slider (43) is slidably connected to the inner wall of the annular groove. A connecting plate (35) is fixedly connected to the side of the slider (43) away from the annular groove. A brush for cleaning the micropores is fixedly connected to the side of the connecting plate (35) near the microporous aeration head (7). A rotatable connecting shaft (31) is vertically arranged inside the microporous aeration head (7). A set of driving blades (32) is fixedly connected to the side wall of the connecting shaft (31). A fixing rod (33) is fixedly connected to the side wall of the micropore corresponding to the connecting shaft (31). A first magnetic block (34) that magnetically attracts the connecting plate (35) is fixedly connected to the side of the fixing rod (33) away from the connecting shaft (31).

6. The photobiological circulating fixed-bed reaction system for purifying urine based on microalgae according to claim 5, characterized in that: The microporous aeration head (7) is slidably connected to the side wall of the gas delivery branch pipe (6). A pair of connecting rods (36) are fixedly connected to the bottom surface of the gas delivery branch pipe (6). A disc (37) is fixedly connected to the bottom surface of the connecting rods (36). The top surface of the connecting shaft (31) is rotatably connected to the disc (37). A ring (38) is slidably connected to the side wall of the disc (37). A set of first springs is fixedly connected between the top surface of the ring (38) and the inner wall of the top surface of the microporous aeration head (7). A second magnetic block (40) is fixedly connected to the top surface of the drive blade (32). A set of magnetic sheets (39) corresponding to the second magnetic block (40) is fixedly connected to the bottom surface of the disc (37). The second magnetic block (40) and the magnetic sheet (39) are arranged in opposition to each other.

7. The photobiological circulating fixed-bed reaction system for purifying urine based on microalgae according to claim 6, characterized in that: The microporous aeration head (7) has a hollow groove (41) and a sealing plate (42) for sealing the micropores is slidably connected inside the hollow groove (41). The sealing plate (42) has a through hole corresponding to the micropore. The inner wall of the microporous aeration head (7) has an air inlet hole that communicates with the hollow groove (41) and the air inlet hole is located on the bottom surface of the sealing plate (42). The outer wall of the microporous aeration head (7) has an air outlet hole that communicates with the hollow groove (41) and the air outlet hole is located on the top surface of the sealing plate (42). A second spring is fixedly connected between the top surface of the sealing plate (42) and the inner wall of the hollow groove (41).

8. A photobiological circulating fixed-bed reaction method for purifying urine based on microalgae, wherein the method employs the photobiological circulating fixed-bed reaction system for purifying urine based on microalgae as described in claim 7, characterized in that: The method includes the following steps: S1: Urine is introduced into the circulating fixed bed reactor through the inlet (16), the outflow branch (22) is connected to the liquid delivery branch (26) of the fixed bed area, the inflow branch (23) is connected to the liquid delivery branch (27) of the outflow area, the peristaltic pump (21) is started, and the urine is circulated and adsorbed in the circulating fixed bed reactor until saturation, and then the peristaltic pump (21) is turned off. S2: Connect the outflow branch (22) to the inflow liquid delivery branch (28), and the inflow branch (23) to the fixed bed liquid delivery branch (26). Turn on the peristaltic pump (21) to discharge the residual urine in the fixed bed into the inflow area, and then turn off the peristaltic pump (21). S3: Inoculate microalgae into the circulating fixed bed reactor through the inlet (16), connect the outflow branch pipe (22) to the inflow liquid transport branch pipe (28), connect the inflow branch pipe (23) to the outflow liquid transport branch pipe (27), and turn on the aerator (1) and peristaltic pump (21) to carry out the circulating cultivation of microalgae. S4: The lighting effect of day and night is distinguished by turning on and off the LED light strip (30). The day and night time is 14 hours and 10 hours respectively. This cycle is continuously repeated. When the microalgae growth reaches a stable state, the aerator (1) and peristaltic pump (21) are turned off.

9. The photobiological circulating fixed-bed reaction method for purifying urine based on microalgae according to claim 8, characterized in that: The method also includes the following steps: S5: The urine and microalgae mixture is discharged through the drain (18). After algae-water separation, the separated urine is collected and introduced into the circulating fixed bed reactor through the inlet (16). Microalgae are inoculated through the inlet (16). S6: During the day, connect the outflow branch pipe (22) to the inflow liquid transport branch pipe (28), and connect the inflow branch pipe (23) to the outflow liquid transport branch pipe (27). Turn on the aerator (1) and the peristaltic pump (21) to carry out suspension culture of microalgae. S7: At night, turn off the aerator (1) and the peristaltic pump (21), connect the outflow branch (22) to the liquid delivery branch (26) of the fixed bed area, connect the inflow branch (23) to the liquid delivery branch (27) of the outflow area, and then turn on the peristaltic pump (21) to regenerate the clinoptilolite packing (15) using urine and microalgae mixture, and realize the microalgae circulation culture based on zeolite. S8: The lighting effect of day and night is distinguished by turning on and off the LED light strip (30). The day and night time is 14 hours and 10 hours respectively. This cycle is continuously repeated. When the microalgae growth reaches a stable state, this process ends. The aerator (1) and peristaltic pump (21) are turned off, and urine and microalgae mixture are discharged from the drain (18) for algae-water separation.

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