Method and device for treating wastewater based on hydrogen autotrophic AOA coupled with cell embedding

Abstract

The application provides a sewage treatment method and device based on hydrogen autotrophic AOA embedding bacteria, and belongs to the technical field of sewage treatment, and comprises the following steps: low-temperature sewage is sequentially treated in an anaerobic zone, an anaerobic-aerobic variable zone, an aerobic zone, an anoxic-aerobic variable zone, an anoxic zone and a hydrogen autotrophic zone, and the final treatment mixed liquor formed after the treatment is introduced into a secondary sedimentation tank for sedimentation and separation, the upper clear water reaches the discharge standard and is discharged, and the sludge deposited at the bottom of the secondary sedimentation tank is partially recycled to the anaerobic zone and partially recycled to the anoxic-aerobic variable zone and the anoxic zone; the anaerobic zone, the aerobic zone and the hydrogen autotrophic zone are all provided with embedding bodies, the embedding technology of bacteria can break through the operation bottleneck of the AOA process in the low-temperature and low-C / N sewage in the north through the synergistic effect of microbial immobilization, microenvironment regulation and functional flora strengthening, improve the low ammonia nitrogen oxidation efficiency of the low-temperature and low-C / N sewage, and solve the problems of loose sludge and sludge loss caused by insufficient carbon source supply, and provides an effective and feasible technical path for deep denitrification of sewage in cold regions.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a wastewater treatment method and apparatus based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA. Background Technology

[0002] Urban wastewater typically exhibits a low carbon-to-nitrogen ratio, posing multiple challenges to traditional biological nitrogen and phosphorus removal processes, including insufficient carbon sources, high operating costs, and increased greenhouse gas emissions. The AOA (Anoxic Oxygen-Oxygen-Oxygenation) process places the anoxic unit after the aerobic unit, creating a new sequence of anaerobic phosphorus release-aerobic nitrification and phosphorus uptake-anoxic endogenous denitrification. This restructuring offers two core advantages: First, the high-quality carbon source in the influent is fully utilized by polyphosphate-accumulating bacteria in the anaerobic stage, enhancing biological phosphorus removal; second, the nitrates produced in the aerobic stage undergo denitrification driven by the internal carbon source within the microorganisms in the subsequent anoxic stage, achieving dual utilization of carbon and improving carbon source efficiency, making it particularly suitable for treating wastewater with a low carbon-to-nitrogen ratio.

[0003] However, in northern regions with low winter temperatures (usually below 15℃) and low C / N ratios (C / N < 5) in wastewater treatment, the core metabolic chain of the AOA process is prone to synergistic imbalance, manifested in limited activity of the two major functional microorganisms and insufficient system stability: On the one hand, the ammonia-oxidizing archaea (AOB) and nitrite-oxidizing bacteria (NOB) in the aerobic stage have long generation cycles (10-30 days) and low specific growth rates. Low temperatures further inhibit the activity of their key enzymes (such as ammonia monooxygenase AMO and nitrite oxidoreductase NOR), resulting in a lower nitrification rate than at room temperature and a sharp drop in ammonia nitrogen oxidation efficiency; on the other hand, the endogenous denitrification process dependent on the anoxic stage requires PHA (polyhydroxyalkanoates) and glycogen stored in the microbial cells as electron donors, while low C / N ratios... Wastewater cannot provide sufficient carbon sources for microorganisms to synthesize intracellular energy storage substances. The carbon sources in the raw water of the anaerobic stage cannot be efficiently decomposed into small molecule organic acids to synthesize sufficient internal carbon sources. This not only leads to a decrease in the denitrification rate, but also requires an extended hydraulic retention time (HRT) to ensure the denitrification effect. Insufficient carbon source supply will also cause the sludge floc structure to loosen and the endogenous respiration of microorganisms to intensify, ultimately leading to sludge disintegration. This further weakens the system's ability to withstand shock loads and forms a vicious cycle of "low temperature - decreased efficiency - sludge loss", which seriously limits the application of the AOA process in low-temperature, low-C / N wastewater in northern regions. Summary of the Invention

[0004] This invention provides a wastewater treatment method and apparatus based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA, aiming to solve the problems of low ammonia nitrogen oxidation efficiency and insufficient carbon source supply in low-temperature, low-C / N wastewater, leading to loose sludge and sludge loss.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA, the method comprising: Low-temperature wastewater is sequentially treated through an anaerobic zone, an anaerobic-aerobic variable zone, an aerobic zone, an anoxic-aerobic variable zone, an anoxic zone, and a hydrogen autotrophic zone. The resulting final treated mixture enters a secondary sedimentation tank for sedimentation and separation. The upper clarified water meets the discharge standards and is discharged. The sludge deposited at the bottom of the secondary sedimentation tank is partially reused in the anaerobic zone and partially reused in the anoxic-aerobic variable zone and the anoxic zone. The anaerobic zone is equipped with a first encapsulation body, which uses polyvinyl alcohol and sodium alginate as gel carriers and encapsulates biochar, hydrolytic acidifying bacteria, and trace elements containing magnesium, cobalt, nickel, and selenium. Low-temperature wastewater is hydrolyzed into small-molecule volatile fatty acids by the first encapsulation body. Polyphosphate-accumulating bacteria / denitrifying polyphosphate-accumulating bacteria in the activated sludge absorb VFA (Volatile Fatty Acid) to synthesize PHA and release phosphate at the same time. Polysaccharide-accumulating bacteria / denitrifying polysaccharide-accumulating bacteria in the activated sludge also utilize VFA to synthesize PHA. Ammonia-oxidizing bacteria convert organic nitrogen into ammonia nitrogen. The aerobic zone contains a second embedded body, which uses polyvinyl alcohol as a gel carrier and embeds ammonia-oxidizing bacteria, sodium alginate, biochar carboxymethyl cellulose, and trace elements containing iron, copper, and magnesium. The embedded ammonia-oxidizing bacteria oxidize ammonia nitrogen into nitrite nitrogen and nitrate nitrogen under aerobic conditions. The hydrogen autotrophic zone is equipped with a third encapsulation body, which uses polyvinyl alcohol as a carrier to encapsulate aerobic hydrogen autotrophic bacteria, aerobic denitrifying bacteria, calcium carbonate, activated carbon, and trace elements containing nickel, iron, molybdenum, selenium, and cobalt. The encapsulated hydrogen autotrophic denitrifying bacteria use hydrogen produced by water electrolysis as an electron donor, without the need for an organic carbon source, to reduce the remaining nitrite and nitrate nitrogen in the water to nitrogen gas. The aerobic denitrifying bacteria in the encapsulation body can also reduce some nitrates to nitrogen gas, and the polyphosphate-accumulating bacteria in the activated sludge can also continue to absorb the remaining phosphates, achieving deep denitrification and phosphorus removal.

[0006] In conjunction with the first aspect, in one feasible manner, the fabrication process of the first embedding body is as follows: Using polyvinyl alcohol as the core framework and sodium alginate as an auxiliary material, a gel carrier is heated to form a gel-like structure. Simultaneously, sludge-based biochar is added to increase mechanical strength, adsorption efficiency, and biocompatibility. A small amount of trace elements containing magnesium, cobalt, nickel, and selenium is added to increase bacterial activity and enhance mass transfer. Then, it is mixed evenly with hydrolyzed acidified concentrated sludge and added to a crosslinking agent by syringe titration to form a porous spherical embedded body. The volume ratio of the gel carrier to the concentrated sludge is 2:1.

[0007] In conjunction with the first aspect, in one feasible manner, the process of fabricating the second embedding body includes: Polyvinyl alcohol is heated to form a gel carrier, which is then mixed with an activated sludge suspension containing ammonia-oxidizing bacteria. Subsequently, a mixed solution of sodium alginate, biochar, carboxymethyl cellulose, and trace elements containing iron, copper, and magnesium ions is added. After being mixed evenly, the mixture is dripped into a crosslinking agent and solidified into a spherical embedded body.

[0008] In conjunction with the first aspect, in one feasible manner, the fabrication process of the third embedding body includes: Polyvinyl alcohol is heated and stirred, and then mixed evenly with aerobic hydrogen autotrophic sludge, aerobic denitrification sludge, calcium carbonate, activated carbon, and a small amount of trace element solution containing nickel, iron, molybdenum, selenium, and cobalt. This mixture is then added to the crosslinking agent in batches to form spherical encapsulated bodies.

[0009] In conjunction with the first aspect, in one feasible manner, the anaerobic zone, the aerobic zone, and the hydrogen autotrophic zone are all provided with embedding bodies, namely, a first embedding body, a second embedding body, and a third embedding body, in sequence.

[0010] In conjunction with the first aspect, in one feasible manner, low-temperature wastewater is operated under low-oxygen conditions: DO < 0.5 mg / L, total nitrogen (TN) in the influent is 40~55 mg / L, ammonia nitrogen is 35~45 mg / L, and C / N ratio is 4~7; The anaerobic-aerobic variable zone operates in anaerobic mode, and the anoxic-aerobic variable zone operates in anoxic mode. The aerobic zone has a filling rate of 35% to 50% for the embedded body, a volume ratio of gel carrier to sludge of 2.5 to 3, and a sludge concentration of 300 mg / L to 600 mg / L. Hydraulic retention time in each zone: anaerobic zone 3.2~4.8h, aerobic zone 2.4~3.6h, anoxic zone 4~6h, hydrogen autotrophic zone 1.6~2.4h; The sludge return rate to the anaerobic zone via the first sludge return pipe is 80-100%, resulting in an oxidation-reduction potential of -180 to -250 mV and a phosphorus release rate of 5.0-7.5 mg PO4 in the anaerobic zone. 3- -P / (gVSS·h); The sludge return rate to the anoxic zone via the second sludge return pipe is 60%~100%.

[0011] In conjunction with the first aspect, in one feasible manner, low-temperature wastewater is operated under conditions of low carbon-to-nitrogen ratio: Low carbon-to-nitrogen ratio (C / N) < 5, influent total nitrogen (TN) 55~75 mg / L, ammonia nitrogen 45~65 mg / L; The anaerobic-aerobic variable zone operates in aerobic mode, while the anoxic-aerobic variable zone operates in anoxic mode. The sludge filling rate in the aerobic zone is 30%~50%; the sludge concentration in the anoxic zone is 500~800 mg / L; and the sludge filling rate in the hydrogen autotrophic zone is 25%~40%. Hydraulic retention time in each zone: anaerobic zone 2.4~3.6h, aerobic zone 3.2~4.8h, anoxic zone 4~6h, hydrogen autotrophic zone 1.6~2.4h; The sludge return ratio to the anaerobic zone via the first sludge return pipe is 100-120%, the oxidation-reduction potential of the anaerobic zone is -100 to -200 mV, and the phosphorus release rate is 3.8-5.2 mg PO4. 3- -P / (gVSS·h); The sludge return ratio to the anoxic-aerobic variable zone via the second sludge return pipe is 100%~150%.

[0012] In conjunction with the first aspect, in one feasible manner, low-temperature wastewater treatment operates under low-temperature conditions of <12°C: Total nitrogen (TN) 45~65 mg / L, ammonia nitrogen 35 mg / L~55 mg / L, C / N ratio 5~7; The anaerobic-aerobic variable zone operates in aerobic mode, and the anoxic-aerobic variable zone operates in aerobic mode. The aerobic zone 5 has a substrate filling rate of 30%~50%, a gel carrier to sludge volume ratio of 1:1, and a sludge concentration of 300mg / L~600mg / L; Hydraulic retention time in each zone: anaerobic zone 2.4~3.6h, aerobic zone 4~6h, anoxic zone 3.2~4.8h, hydrogen autotrophic zone 1.6~2.4h; The sludge return ratio to the anaerobic zone via the first sludge return pipe is 100-120%, the oxidation-reduction potential of the anaerobic zone is -150 to -250 mV, and the phosphorus release rate is 2.5-4.6 mg PO4. 3- -P / (gVSS·h); The sludge return ratio for the anoxic zone via the second sludge return pipe is 100%~120%.

[0013] Secondly, embodiments of the present invention also provide a wastewater treatment device based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA, used in the aforementioned wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA, comprising an anaerobic zone, an anaerobic-aerobic variable zone, an aerobic zone, an anoxic-aerobic variable zone, an anoxic zone, a hydrogen autotrophic zone, and a secondary sedimentation tank connected in sequence; the bottom of the secondary sedimentation tank is connected to the anaerobic zone through a first sludge return pipe, and to the anoxic-aerobic variable zone and the anoxic zone through a second sludge return pipe; Solar panels are laid above the anaerobic zone, the anoxic zone, and the hydrogen autotrophic zone; Permeable nets are installed at the connecting points between the zones.

[0014] The wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA provided by this invention has the following advantages compared with existing technologies: This invention provides a solution for optimizing the low-temperature and low C / N adaptability of the AOA process by using bacterial cell encapsulation and coupled with hydrogen autotrophy. Specifically, the encapsulating body uses polyvinyl alcohol (PVA) and / or sodium alginate (SA) as a composite gel carrier. Functional bacterial groups such as hydrolytic acidifying bacteria, ammonia oxidizing bacteria, and hydrogen autotrophic denitrifying bacteria are encapsulated within the porous carrier using encapsulation technology, forming a core-shell or porous spherical encapsulating body. The advantages are as follows: First, through the spatial retention effect of the encapsulation body, the density of functional bacteria can be increased to 2-3 times that of the suspended system, effectively solving the problem of microbial loss at low temperatures. At the same time, the physical barrier of the encapsulation body can isolate the inhibition of bacteria by toxic substances such as heavy metals and antibiotics in sewage.

[0015] Secondly, the interior of the embedded body forms a natural "aerobic-anoxic" micro-gradient environment due to oxygen diffusion resistance. The external aerobic zone can enhance aerobic denitrification, while the interior provides a suitable habitat for hydrogen autotrophic denitrifying bacteria. These bacteria use hydrogen as an electron donor and do not rely on organic carbon sources. They can efficiently reduce nitrification products NO2⁻-N and NO3⁻-N to N2, making up for the lack of carbon sources in endogenous denitrification under low C / N conditions, and realizing the in-situ coupling of "aerobic denitrification-hydrogen autotrophic denitrification".

[0016] Third, the three-dimensional network structure of the embedded body can protect microorganisms from low temperature stress. By adding antifreeze agents such as glycerol and ethylene glycol, the low temperature activity of the microbial community can be further enhanced, so that the nitrification rate can maintain a high activity under conditions of <15℃. Materials such as nano iron powder and trace elements can also be added to increase the activity of biological enzymes and improve the metabolic rate of the microbial community.

[0017] In summary, the microbial cell encapsulation technology, through the synergistic effect of microbial immobilization, microenvironment regulation, and functional microbial community enhancement, can overcome the operational bottleneck of the AOA process in low-temperature, low-C / N wastewater in northern regions, providing an efficient and feasible technical path for deep denitrification of wastewater in cold regions.

[0018] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this specification. Attached Figure Description

[0020] Figure 1 A schematic diagram of the structure of a wastewater treatment device based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA provided in an embodiment of the present invention; Explanation of reference numerals in the attached figures: 1. Water tank; 2. Inlet pump; 3. Anaerobic zone; 4. Variable anaerobic / aerobic zone; 5. Aerobic zone; 6. Variable anoxic / aerobic zone; 7. Anoxic zone; 8. Hydrogen autotrophic zone; 9. Secondary sedimentation tank; 10. First sludge return pump; 11. First sludge return pipe; 12. Second sludge return pump; 13. Second sludge return pipe; 14. Power supply unit; 15. Computer; 16. PLC controller; 17. Blower; 18. Aeration head; 19. Electrolysis electrode; 20. Handheld dissolved oxygen probe; 21. Solar panel; 22. Electric stirrer; 23. Dissolved hydrogen online detection probe; 24. Oxidation-reduction potential probe; 25. Nitrate and nitrite monitoring probe; 26. Phosphate detection probe; 27. Dissolved oxygen detection probe; 28. Ammonia nitrogen detection probe; 29. ​​Embedded body. Detailed Implementation

[0021] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0022] Unless otherwise expressly defined, the use of terms such as "first," "second," or "third" in the claims, description, and accompanying drawings of this invention is for distinguishing different objects and not for describing a specific order.

[0023] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceeding" are understood to exclude the stated number; expressions such as "above," "below," and "within" are understood to include the stated number. Furthermore, in the description of the embodiments in this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times," unless otherwise explicitly specified.

[0024] In the claims, description and accompanying drawings of this invention, the terms "comprising," "having," and variations thereof are used to mean "including but not limited to."

[0025] Urban wastewater generally exhibits a low carbon-to-nitrogen ratio. Traditional simultaneous nitrogen and phosphorus removal processes, represented by A²O, have inherent drawbacks: their anaerobic-anoxic-aerobic unit sequence leads to competition for limited influent carbon sources between denitrification and phosphorus release by polyphosphate-accumulating organisms (PAOs) in the anoxic zone. Furthermore, nitrates produced in the aerobic zone are recirculated into the anaerobic zone, disrupting the strictly anaerobic environment required by PAOs and severely limiting nitrogen and phosphorus removal efficiency. To address this challenge, researchers have proposed the AOA process, which involves process reconfiguration.

[0026] However, existing AOA processes also have some shortcomings. The design concept of this invention is to innovatively integrate the process advantages of AOA, the biomass retention and microenvironment regulation advantages of encapsulation technology, and the clean driving force advantage of hydrogen autotrophic denitrification, forming a complete technology chain to break through the current bottleneck of deep wastewater treatment. Its core concept is: to introduce pre-cultured hydrolytic acidifying bacteria, ammonia oxidizing bacteria, and hydrogen autotrophic denitrifying bacteria into the reaction zone of the AOA process. On the one hand, the encapsulated material provides a stable environment for the enrichment, proliferation, and retention of functional bacteria, overcoming their disadvantages of slow growth and easy sludge bulking. On the other hand, the synthetic material of the encapsulated material can be a high-carbon material, such as biochar prepared from waste sludge. Its strong adsorption capacity and internal structure enhance the mass transfer effect of the encapsulated material, greatly enhancing the ability of short-cut nitrification and hydrogen autotrophic denitrification, and even achieving aerobic denitrification + hydrogen autotrophic denitrification coupling, thereby deeply and stably removing nitrogen and phosphorus pollutants without the need for external organic carbon sources. Thirdly, the encapsulated material has the characteristics of large particle size, high density, and good settling performance, and is not easily lost, which can reduce the sludge production of the system, reduce the burden of subsequent treatment, facilitate maintenance and operation, and reduce investment and operating costs.

[0027] In the text, A²O (or AAO) process is short for "anaerobic-anoxic-oxic" biological nitrogen and phosphorus removal process, which is the mainstream wastewater treatment technology for the simultaneous removal of organic matter, nitrogen and phosphorus; AOA process is short for "anaerobic-aerobic-anoxic" method.

[0028] Please see Figure 1 The wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA provided by the present invention will now be described. The wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA includes: low-temperature wastewater sequentially passing through an anaerobic zone 3, an anaerobic-aerobic variable zone 4, an aerobic zone 5, an anoxic-aerobic variable zone 6, an anoxic zone 7, and a hydrogen autotrophic zone 8 for treatment; the resulting final treated mixture enters a secondary sedimentation tank 9 for sedimentation and separation; the upper clarified water meets the discharge standards and is discharged; the sludge deposited at the bottom of the secondary sedimentation tank 9 is partially reused in the anaerobic zone 3 and partially reused in the anoxic-aerobic variable zone 6.

[0029] The anaerobic zone 3 contains a first encapsulation body, which uses polyvinyl alcohol and sodium alginate as gel carriers and encapsulates biochar, hydrolytic acidifying bacteria, and trace elements containing magnesium, cobalt, nickel, and selenium. Low-temperature wastewater is hydrolyzed into small-molecule volatile fatty acids by the first encapsulation body. Polyphosphate-accumulating bacteria / denitrifying polyphosphate-accumulating bacteria in the activated sludge absorb VFA to synthesize PHA and release phosphates at the same time. Polysaccharide-accumulating bacteria / denitrifying polysaccharide-accumulating bacteria in the activated sludge also utilize VFA to synthesize PHA. Ammonia-oxidizing bacteria convert organic nitrogen into ammonia nitrogen.

[0030] The aerobic zone 5 contains a second embedded body. The second embedded body uses polyvinyl alcohol as a gel carrier and embeds ammonia-oxidizing bacteria, sodium alginate, biochar, carboxymethyl cellulose, and trace elements containing iron, copper, and magnesium. The embedded ammonia-oxidizing bacteria oxidize ammonia nitrogen into nitrite nitrogen and nitrate nitrogen in an aerobic environment.

[0031] The hydrogen autotrophic zone 8 is equipped with a third encapsulation body. The third encapsulation body uses polyvinyl alcohol as a carrier to encapsulate aerobic hydrogen autotrophic bacteria, aerobic denitrifying bacteria, calcium carbonate, activated carbon, and trace elements containing nickel, iron, molybdenum, selenium, and cobalt. The encapsulated hydrogen autotrophic denitrifying bacteria use hydrogen produced by water electrolysis as an electron donor, without the need for an organic carbon source, to reduce the remaining nitrite and nitrate nitrogen in the water to nitrogen gas. The aerobic denitrifying bacteria in the encapsulation body can also reduce some nitrates to nitrogen gas, and the polyphosphate-accumulating bacteria in the activated sludge can also continue to absorb the remaining phosphates, achieving deep denitrification and phosphorus removal.

[0032] Compared with existing technologies, this embodiment demonstrates that the microbial cell encapsulation technology, through the synergistic effect of microbial immobilization, microenvironment regulation, and functional microbial community enhancement, can overcome the operational bottleneck of the AOA process in low-temperature, low-C / N wastewater in northern regions. It solves the problems of low ammonia nitrogen oxidation efficiency and insufficient carbon source supply leading to sludge loosening and loss in low-temperature, low-C / N wastewater, providing an efficient and feasible technical path for deep denitrification of wastewater in cold regions.

[0033] In some embodiments, the first embedded body is filled in the anaerobic zone 3. The manufacturing process of the first embedded body is as follows: using polyvinyl alcohol (PVA) as the core framework (as the main matrix) and sodium alginate (SA) as an auxiliary material (to assist in rapid molding), it is heated into a gel-like gel carrier. At the same time, sludge biochar is added to increase mechanical strength, adsorption efficiency and biocompatibility; a small amount of trace elements containing magnesium, cobalt, nickel and selenium are added to increase the carbon source uptake rate of hydrolytic acidifying bacteria; then, after being mixed evenly with the concentrated sludge of hydrolytic acidifying bacteria, it is added to the crosslinking agent by syringe titration to form a porous spherical embedded body with a diameter of 3~5mm; wherein, the volume ratio of the gel carrier to the concentrated sludge is 2:1.

[0034] In some embodiments, the second embedding body is filled in the aerobic zone 5. The process of making the second embedding body includes: heating polyvinyl alcohol into a gel to form a gel carrier, mixing it with an ammonia-oxidizing bacteria suspension (volume ratio of 2:1), then adding sodium alginate (main carrier material), biochar (to increase carrier adsorption efficiency and biocompatibility), carboxymethyl cellulose (to improve mechanical strength), and a small amount of trace elements containing iron, copper, and magnesium ions (to increase the nitrification efficiency of ammonia-oxidizing bacteria), mixing them evenly, and then dripping them into a crosslinking agent to solidify them into a spherical embedding body (diameter 2-3 mm).

[0035] In some embodiments, the third embedding body is filled in the hydrogen autotrophic zone 8. The manufacturing process includes: heating and stirring polyvinyl alcohol (PVA) to dissolve and mix it, then mixing it with a certain proportion of concentrated sludge (the volume ratio of carrier material to sludge is 1:1, and the embedding bacteria are hydrogen autotrophic bacteria and aerobic denitrifying bacteria), calcium carbonate (pore-forming agent, which increases porosity and thus improves mass transfer efficiency), activated carbon (which increases adsorption and increases bacterial load), and a small amount of trace element solution containing nickel, iron, molybdenum, selenium, and cobalt (which improves enzyme activity and metabolic capacity), and adding it to the crosslinking agent to form a spherical embedding body with a diameter of 2-4 mm.

[0036] The working mechanism of each encapsulated zone is as follows: Wastewater containing a certain concentration of nitrogen and phosphorus organic matter enters the anaerobic zone. Easily degradable organic matter is hydrolyzed into small molecule volatile fatty acids by the encapsulated fermenting acid-producing bacteria. These small molecule volatile fatty acids are then absorbed and stored intracellularly by polyphosphate-accumulating bacteria in the sludge system. The polyphosphate-accumulating bacteria hydrolyze the polyphosphate stored intracellularly, releasing the phosphate into the water body, resulting in an increase in the phosphate concentration in the water body. The encapsulated fermenting bacteria will ammonify and decompose the organic nitrogen in the water, converting it into ammonia nitrogen, while the nitrate nitrogen, nitrite nitrogen and total nitrogen content remain basically unchanged.

[0037] Then, the water enters aerobic zone 5, where the remaining easily degradable organic matter is degraded by heterotrophic bacteria. At the same time, the aerobic denitrification process continuously consumes organic matter as an electron donor. The encapsulated ammonia-oxidizing bacteria oxidize ammonia nitrogen mainly into nitrite nitrogen and a small amount of nitrate nitrogen in an aerobic environment. Polyphosphate-accumulating bacteria decompose the energy substances stored in their cells to obtain power, absorb excessive amounts of phosphate from the water, and convert it into polyphosphate stored in their cells, thus reducing the phosphate concentration.

[0038] Upon entering the anoxic zone 7, the heterotrophic denitrifying bacteria in the sludge utilize the remaining organic matter in the water as electron donors to gradually reduce nitrite and nitrate nitrogen into nitrogen gas. At the same time, denitrifying polyphosphate-accumulating bacteria and denitrifying polysaccharide bacteria utilize the internal carbon source synthesized in the anaerobic zone, using nitrite and nitrate nitrogen as electron acceptors, to carry out endogenous denitrification and denitrification phosphorus removal under anoxic conditions, further reducing nitrogen and phosphorus content.

[0039] Finally, it enters the hydrogen autotrophic zone 8, where the encapsulated hydrogen autotrophic denitrifying bacteria use hydrogen produced by water electrolysis as an electron donor, requiring no organic carbon source, to reduce the remaining nitrite and nitrate nitrogen in the water to nitrogen gas; the aerobic denitrifying bacteria in the encapsulated body can reduce some nitrate to nitrogen gas, and the polyphosphate-accumulating bacteria in the activated sludge can also continue to absorb the remaining phosphate, achieving deep denitrification and phosphorus removal.

[0040] In some embodiments, the anaerobic zone 3, the aerobic zone 5, and the hydrogen autotrophic zone 8 are each provided with an embedding body 29, which are, in sequence, a first embedding body, a second embedding body, and a third embedding body.

[0041] In the above embodiments, each reaction zone is provided with a small amount of sludge (500-1000 mg / L), and the filling rate of the embedded body 29 is 20%-30% of the effective volume of the reaction zone. A filter screen is arranged on the effluent side of the partition between each adjacent zone to allow the influent to flow while preventing the embedded body from being lost or dispersed.

[0042] Combination Figure 1 The embodiments provided by this invention under various conditions are understood as follows: Example 1: Operating mode and parameters under hypoxic conditions Low oxygen (DO<0.5mg / L), total nitrogen (TN) in the influent is 40~55mg / L (of which ammonia nitrogen is 35~45mg / L), and C / N ratio is 4~7.

[0043] Low oxygen levels (DO < 0.5 mg / L) limit the nitrification efficiency in the aerobic zone, but at the same time promote the nitrogen removal and anaerobic ammonia oxidation effects of simultaneous nitrification and denitrification, which can give full play to the endogenous synthesis in anaerobic environments. The anaerobic zone has 4 compartments. The anaerobic-aerobic variable zone 4 operates in anaerobic mode, and the anoxic-aerobic variable zone 6 operates in anoxic mode. Therefore, the aerobic zone has 3 compartments. The filling rate of the embedded body 29 is 35%~50% (the filling rate has increased from the original 20~30% to 35%~50%). The concentration of the embedded sludge is appropriately reduced (the volume ratio is 2.5~3), and the stirring rate is appropriately increased to increase oxygen utilization and improve the nitrification and ammonia oxidation efficiency, so that the nitrification rate is 10.0~16.0 mg / (L·h) and the phosphorus uptake rate is 2.0~3.5 mg / (L·h). The sludge concentration in the aerobic zone is appropriately reduced to 300 mg / L~600 mg / L, and the particle size of the embedded body in the aerobic zone is reduced (2~4 mm) to increase the specific surface area and mass transfer efficiency.

[0044] Hydraulic retention time in each zone: anaerobic zone 3.2~4.8h, aerobic zone 2.4~3.6h, anoxic zone 4~6h, hydrogen autotrophic zone 1.6~2.4h.

[0045] Adjust the sludge return ratio from the first sludge return pipe 11 to the anaerobic zone to 80-100%, so that the oxidation-reduction potential of the anaerobic zone is -180 to -250 mV and the phosphorus release rate is 5.0-7.5 mg PO4. 3- -P / (gVSS·h); the denitrification rate in the anoxic zone is 4.0~8.0 mg / (L·h), and the sludge return ratio of the second sludge return pipe 13 to the anoxic-aerobic variable zone 6 is adjusted to 100%~130%.

[0046] 50%–75% of the solar-collected electrical energy is used for electrolysis in the hydrogen autotrophic zone, and the remainder is used for storage. The electrolysis current intensity is 0.60–0.90 mA / cm², the dissolved hydrogen concentration is 0.3–0.6 mg / L, and the denitrification rate is 5.0–9.0 mg / (L·h).

[0047] Example 2: Operating mode and parameters under low carbon-to-nitrogen ratio conditions When the carbon-to-nitrogen ratio is low (C / N<5), the internal carbon source is insufficient, and the total nitrogen (TN) in the influent is approximately 55~75 mg / L (of which ammonia nitrogen is 45~65 mg / L). It is necessary to rely on hydrogen autotrophic denitrification to supplement the denitrification efficiency, while strengthening the microbial community enrichment of the embedded body.

[0048] The anaerobic zone has 3 compartments. The anaerobic-aerobic variable zone 4 operates in aerobic mode, and the aerobic zone 5 has 4 compartments. The dissolved oxygen concentration is appropriately reduced to minimize dissolved oxygen entering the anoxic zone. The aerobic zone's encapsulation filling rate is 30%~50% of the effective volume of the reaction zone, increasing nitrogen oxidation efficiency, with a nitrification rate of 25~40 mg / (L·h) and a phosphorus uptake rate of 0.5~1.5 mg / (L·h). The anoxic-aerobic variable zone 6 operates in anoxic mode, and the anoxic zone 7 has 5 compartments to enhance endogenous denitrification.

[0049] Hydraulic retention time in each zone: anaerobic zone 2.4~3.6h, aerobic zone 3.2~4.8h, anoxic zone 4~6h, hydrogen autotrophic zone 1.6~2.4h.

[0050] The sludge return ratio of the first sludge return pipe 11 is 100~120%, the oxidation-reduction potential of the anaerobic zone is -100~-200mV, and the phosphorus release rate is 3.8~5.2mgPO4. 3- -P / (gVSS·h); the denitrification rate in the anoxic zone is 2.5~7.5mg / (L·h), and the sludge return ratio of the second sludge return pipe 13 is 100%~150%.

[0051] 55%–80% of the solar-collected electricity is used for electrolysis in the hydrogen autotrophic zone, and the remainder is used for storage. When the nitrate concentration at the outlet is >8 mg / L, auxiliary current is required for electrolysis in the absence of sunlight. The electrolysis current intensity is 0.90–1.25 mA / cm², the dissolved hydrogen concentration is 0.4–0.8 mg / L, the denitrification rate is 6.0–12.5 mg / (L·h), and the burial and filling rate of the hydrogen autotrophic zone 8 is 25%–40%.

[0052] Meanwhile, during the preparation of the embedded body in the hydrogen autotrophic zone 8, micron-sized zero-valent iron can be added to increase electron transfer efficiency, thereby increasing the microbial metabolic rate and the reduction capacity of the treatment system.

[0053] Example 3: Operating mode and parameters under low temperature conditions Low temperatures (<12℃) will further inhibit microbial activity, so it is necessary to increase the concentration of bacteria and strengthen the energy supply. The influent TN value should be 45~65mg / L (ammonia nitrogen 35mg / L~55mg / L), and the C / N ratio should be 5~7.

[0054] The anaerobic zone has 3 compartments. The anaerobic-aerobic variable zone 4 operates in aerobic mode, the anoxic-aerobic variable zone 6 operates in aerobic mode, and the aerobic zone 5 has 5 compartments to enhance the ammonia oxidation effect in the aerobic zone. The filling rate of the aerobic zone's carrier is 30%~50%, which increases the dissolved oxygen concentration in the aerobic zone and improves the concentration of carrier bacteria. The volume ratio of carrier material to sludge is 1:1, the nitrification rate is 16~24 mg / (L·h), and the phosphorus uptake rate is 1.5~3 mg / (L·h).

[0055] Hydraulic retention time in each zone: anaerobic zone 2.4~3.6h, aerobic zone 4~6h, anoxic zone 3.2~4.8h, hydrogen autotrophic zone 1.6~2.4h.

[0056] The sludge return ratio of the first sludge return pipe 11 is 100~120%, the oxidation-reduction potential of the anaerobic zone is -150~-250mV, and the phosphorus release rate is 2.5~4.6mgPO4. 3- -P / (gVSS·h); Second sludge return pipe 13 sludge return ratio 100%~120%, anoxic zone denitrification rate 2.5~5.5mg / (L·h).

[0057] 70%–85% of the solar-collected electrical energy is used for electrolysis in the hydrogen autotrophic zone, and the remainder is used for storage. The solar panels continuously absorb heat to combat the low temperature. The electrolysis current intensity is 0.80–1.10 mA / cm², the dissolved hydrogen concentration is 0.4–0.6 mg / L, and the denitrification rate is 5.5–10 mg / (L·h).

[0058] The embedded microbial strains in each zone can be low-temperature acclimatized strains. At the same time, antifreeze agents can be added during the preparation of the embedded body to resist the inhibition of microbial activity by low temperature.

[0059] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0060] Based on the same inventive concept, this application also provides a wastewater treatment device based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA, used in the aforementioned wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA. Please refer to [link to relevant documentation]. Figure 1 As shown, the system includes an anaerobic zone 3, an anaerobic-aerobic variable zone 4, an aerobic zone 5, an anoxic-aerobic variable zone 6, an anoxic zone 7, a hydrogen autotrophic zone 8, and a secondary sedimentation tank 9, which are connected in sequence. The bottom of the secondary sedimentation tank 9 is connected to the anaerobic zone 3 through a first sludge return pipe 11, and to the anoxic-aerobic variable zone 6 and the anoxic zone 7 through a second sludge return pipe 13. Solar panels 21 are laid above the anaerobic zone 3, the anoxic zone 7, and the hydrogen autotrophic zone 8. Permeable nets are installed at the connecting openings between the partitions of each zone.

[0061] This device can generate electricity using solar panels 21, or the current can be increased by an auxiliary power source. By placing electrodes in two hydrogen autotrophic zones 8 at the end of the anoxic zone 7, hydrogen gas is generated in the cathode zone. Hydrogen autotrophic bacteria use hydrogen gas as an electron donor. 3- NO 2- As an electron acceptor, it undergoes denitrification to generate N2, thereby removing nitrogen.

[0062] Specifically, water tank 1 is connected to anaerobic zone 3 via inlet pump 2. Anaerobic-aerobic variable zone 4, aerobic zone 5, anoxic-aerobic variable zone 6, anoxic zone 7 and hydrogen autotrophic zone 8 are sequentially connected. Hydrogen autotrophic zone 8 is connected to secondary sedimentation tank 9. Part of the sludge at the lower end of secondary sedimentation tank 9 is discharged through sludge discharge pipe, another part is connected to anaerobic zone 3 via first sludge return pump 10 and first sludge return pipe 11, and another part is connected to anoxic-aerobic variable zone 6 and anoxic zone 7 via second sludge return pump 12 and second sludge return pipe 13.

[0063] The power collection device 14 is connected to the computer 15 as a control switch for the device. It can be charged and stored by the solar panel 21, and can also provide power when the power supply is insufficient. The computer 15 is connected to the PLC controller 16 to monitor the data of the dissolved hydrogen online detection probe 23 (located in the anaerobic zone 3), the oxidation-reduction potential probe 24 (located in the anaerobic zone 3), the nitrate and nitrite monitoring probe 25, the phosphate detection probe 26, and the ammonia nitrogen detection probe 28 in real time. The PLC controller 16 is connected to the blower 17 to control the operating power. The hydrogen autotrophic zone 8 is equipped with an electrolysis electrode 19, and the aerobic zone 5 and the anaerobic-aerobic variable zone 4 are equipped with handheld dissolved oxygen probes 20. Each zone is equipped with an electric stirrer 22 and an embedded body 29, and each zone is equipped with an aeration head 18.

[0064] Dissolved oxygen detection probe 27 is installed in both the anaerobic-aerobic variable zone 4 and the aerobic zone 5; ammonia nitrogen detection probe 28 is installed in the aerobic zone 5; nitrate and nitrite monitoring probe 25 is installed in the aerobic zone 5 (one probe), the anoxic zone 7 (two probes), and the hydrogen autotrophic zone 8 (one probe); and dissolved hydrogen online detection probe 23 is installed in the hydrogen autotrophic zone 8.

[0065] Each sludge return pipe is equipped with a control valve to allow for on / off switching as needed.

[0066] The outlets between each zone are equipped with permeable nets to prevent the embedded body from escaping while allowing water to flow through. Solar panels are laid on top of the entire reaction zone, with reserved openings to improve the utilization rate of light and heat energy.

[0067] For hydrogen evolution, a carbon rod is used as the anode and a stainless steel wire mesh is used as the cathode. To reduce internal resistance, a thin plastic mesh of a certain thickness is placed, separating the cathode from the carbon rod anode through the thin plastic mesh, thus separating the anode and cathode; the carbon rod is surrounded by the thin plastic mesh, and the stainless steel wire mesh is wound around the outside of the plastic mesh.

[0068] 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, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA, characterized in that, The method includes: Low-temperature wastewater is sequentially treated in an anaerobic zone (3), an anaerobic-aerobic variable zone (4), an aerobic zone (5), an anoxic-aerobic variable zone (6), an anoxic zone (7), and a hydrogen autotrophic zone (8). The resulting final treated mixture enters a secondary sedimentation tank (9) for sedimentation and separation. The clarified water in the upper layer meets the discharge standards and is discharged. The sludge deposited at the bottom of the secondary sedimentation tank (9) is partially reused in the anaerobic zone (3), and partially reused in the anoxic-aerobic variable zone (6) and the anoxic zone (7). The anaerobic zone (3) is provided with a first embedded body, which uses polyvinyl alcohol and sodium alginate as gel carriers and embeds biochar, hydrolytic acidifying bacteria and trace elements containing magnesium, cobalt, nickel and selenium. The aerobic zone (5) is provided with a second embedded body, which uses polyvinyl alcohol as a gel carrier and embeds ammonia-oxidizing bacteria, sodium alginate, biochar, carboxymethyl cellulose, and trace elements containing iron, copper, and magnesium. The hydrogen autotrophic zone (8) is provided with a third embedding body, which uses polyvinyl alcohol as a carrier to embed aerobic hydrogen autotrophic bacteria, aerobic denitrifying bacteria, calcium carbonate, activated carbon and trace elements containing nickel, iron, molybdenum, selenium and cobalt.

2. The wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA as described in claim 1, characterized in that, The fabrication process of the first embedded body is as follows: Polyvinyl alcohol is used as the core framework and sodium alginate is used as an auxiliary material. The gel carrier is heated into a gel-like state and sludge biochar and trace elements containing magnesium, cobalt, nickel and selenium are added. Then, it is mixed evenly with hydrolyzed acidified concentrated sludge and added to the crosslinking agent to form a porous spherical embedded body (29). The volume ratio of the gel carrier to the concentrated sludge is 2:

1.

3. The wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA as described in claim 1, characterized in that, The process of fabricating the second embedding body includes: Polyvinyl alcohol is heated to form a gel carrier, which is then mixed with an ammonia-oxidizing bacteria activated sludge suspension. A mixed solution of sodium alginate, biochar, carboxymethyl cellulose, and trace elements containing iron, copper, and magnesium is added, stirred evenly, and then added to a crosslinking solution to form a spherical embedded body.

4. The wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA as described in claim 1, characterized in that, The process of fabricating the third embedding body includes: Polyvinyl alcohol is heated and stirred, and then mixed evenly with aerobic hydrogen autotrophic sludge, aerobic denitrification sludge, calcium carbonate, activated carbon, and trace element solution containing nickel, iron, molybdenum, selenium, and cobalt. This mixture is then added to the crosslinking agent in batches to form spherical encapsulated bodies.

5. The wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA as described in claim 1, characterized in that, The anaerobic zone (3), the aerobic zone (5), and the hydrogen autotrophic zone (8) are all provided with embedding bodies (29), namely the first embedding body, the second embedding body, and the third embedding body, in sequence.

6. The wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA as described in claim 1, characterized in that, Low-temperature wastewater operates under low-oxygen conditions: DO < 0.5 mg / L, total nitrogen (TN) in the influent is 40~55 mg / L, ammonia nitrogen is 35~45 mg / L, and C / N ratio is 4~7; The anaerobic-aerobic variable zone (4) operates in anaerobic mode, and the hypoxic-aerobic variable zone (6) operates in hypoxic mode; The aerobic zone has a filling rate of 35% to 50% for the embedded body, a volume ratio of gel carrier to sludge of 2.5 to 3, and a sludge concentration of 300 mg / L to 600 mg / L. Hydraulic retention time in each zone: anaerobic zone 3.2~4.8h, aerobic zone 2.4~3.6h, anoxic zone 4~6h, hydrogen autotrophic zone 1.6~2.4h; The sludge return ratio to the anaerobic zone via the first sludge return pipe (11) is 80-100%, resulting in an oxidation-reduction potential of -180 to -250 mV and a phosphorus release rate of 5.0-7.5 mg PO4 in the anaerobic zone. 3- -P / (gVSS·h); The sludge return ratio to the anoxic zone (7) via the second sludge return pipe (13) is 60%~100%.

7. The wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA as described in claim 1, characterized in that, Low-temperature wastewater treatment operates under low carbon-to-nitrogen ratio conditions: Low carbon-to-nitrogen ratio (C / N) < 5, influent total nitrogen (TN) 55~75 mg / L, ammonia nitrogen 45~65 mg / L; The anaerobic-aerobic variable zone (4) operates in aerobic mode, and the hypoxic-aerobic variable zone (6) operates in hypoxic mode. The sludge filling rate in the aerobic zone is 30%~50%; the sludge concentration in the anoxic zone is 500~800 mg / L; and the sludge filling rate in the hydrogen autotrophic zone is 25%~40%. Hydraulic retention time in each zone: anaerobic zone 2.4~3.6h, aerobic zone 3.2~4.8h, anoxic zone 4~6h, hydrogen autotrophic zone 1.6~2.4h; The sludge return ratio to the anaerobic zone (3) via the first sludge return pipe (11) is 100~120%, the oxidation-reduction potential of the anaerobic zone is -100~-200mV, and the phosphorus release rate is 3.8~5.2mgPO4. 3- -P / (gVSS·h); The sludge return ratio to the anoxic-aerobic variable zone (6) via the second sludge return pipe (13) is 100%~150%.

8. The wastewater treatment method based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA as described in claim 1, characterized in that, Low-temperature wastewater treatment operates under low-temperature conditions (<12℃): Total nitrogen (TN) 45~65 mg / L, ammonia nitrogen 35 mg / L~55 mg / L, C / N ratio 5~7; The anaerobic-aerobic variable zone (4) operates in aerobic mode, and the hypoxic-aerobic variable zone (6) operates in aerobic mode. The aerobic zone (5) has an embedding rate of 30%~50%, a gel carrier to sludge volume ratio of 1:1, and a sludge concentration of 300mg / L~600mg / L; Hydraulic retention time in each zone: anaerobic zone 2.4~3.6h, aerobic zone 4~6h, anoxic zone 3.2~4.8h, hydrogen autotrophic zone 1.6~2.4h; The sludge return ratio to the anaerobic zone via the first sludge return pipe (11) is 100~120%, the oxidation-reduction potential of the anaerobic zone is -150~-250mV, and the phosphorus release rate is 2.5~4.6mgPO4. 3- -P / (gVSS·h); The sludge return ratio to the anoxic zone (7) via the second sludge return pipe (13) is 100%~120%.

9. An apparatus for wastewater treatment based on bacterial cell encapsulation coupled with hydrogen autotrophic AOA as described in any one of claims 1-8, characterized in that, It includes an anaerobic zone (3), an anaerobic-aerobic variable zone (4), an aerobic zone (5), an anoxic-aerobic variable zone (6), an anoxic zone (7), a hydrogen autotrophic zone (8), and a secondary sedimentation tank (9) connected in sequence; the bottom of the secondary sedimentation tank (9) is connected to the anaerobic zone (3) through a first sludge return pipe (11), and connected to the anoxic-aerobic variable zone (6) and the anoxic zone (7) through a second sludge return pipe (13); Solar panels (21) are laid above the anaerobic zone (3), the anoxic zone (7) and the hydrogen autotrophic zone (8); Permeable nets are installed at the connecting points between the zones.

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