Device and method for denitrification and dephosphorization of sewage without external carbon source

Abstract

The present application belongs to the field of sewage treatment, and particularly relates to a sewage resourceization denitrification and phosphorus removal device and method without external carbon source. The technical scheme of the present application is as follows: a sewage resourceization denitrification and phosphorus removal device without external carbon source comprises sequentially connected anoxic (deficient oxygen) reactor, aerobic reactor, sedimentation tank and photosynthetic algae reactor; the operation mode is adjusted according to the nitrogen and phosphorus indexes of effluent, has the characteristics of simple process, no need to add chemical phosphorus removal reagent, no need to add external carbon source, no need to mechanical aeration, no need to discharge residual sludge, close to zero carbon emission, etc., can treat nitrogen and phosphorus pollutants of various concentrations, and when the effluent effect is best, can reach the III standard limit value of surface water environmental quality standard (GB3838-2020).

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment, specifically relating to a wastewater resource recovery device and method for nitrogen and phosphorus removal without external carbon sources. Background Technology

[0002] For water bodies, the most serious problem caused by excessive nitrogen and phosphorus is eutrophication. Eutrophication refers to the phenomenon where, under the influence of human activities, large amounts of nutrients such as nitrogen and phosphorus enter lakes, reservoirs, rivers, and other water bodies, leading to an excess of nutrients in the water, the proliferation of aquatic plants and algae, resulting in decreased water transparency, reduced dissolved oxygen, changes in water quality, and mass mortality of fish and other organisms. When algal remains decompose, they further consume dissolved oxygen, producing toxic and harmful substances during the decomposition process, causing mass mortality of other aquatic organisms. When a single type of algae controls a water body, biodiversity decreases, leading to water quality deterioration. In recent years, although the country has continuously increased its efforts to control nitrogen and phosphorus pollutants and has attached great importance to the problem of lake eutrophication, the task of addressing eutrophication remains arduous and challenging.

[0003] Currently, the main methods for removing nitrogen and phosphorus from water bodies include physical, chemical, and biological methods. Compared with physical and chemical methods, biological nitrogen and phosphorus removal processes are widely used in existing wastewater treatment plants due to their economic advantages. The basic principle is to effectively remove total nitrogen (TN) from wastewater by converting nitrogen-containing compounds in the water into harmless nitrogen gas (N2); and to stably remove total phosphorus (TP) from the wastewater by enriching phosphorus in the sludge. In the actual use and operation of traditional biological nitrogen and phosphorus removal processes, both nitrogen and phosphorus removal require carbon. During biological denitrification, denitrifying bacteria use carbon sources as electron donors to reduce nitrates. When the content of organic carbon sources is insufficient, it often leads to a large accumulation of nitrites, making it difficult for biological denitrification to proceed completely. During phosphorus removal, the influent C / P ratio is a key factor affecting the competition of energy pools within polyphosphate-accumulating bacteria and polysaccharide-accumulating bacteria, because both utilize internally stored polyphosphates and sugar sources as energy for the synthesis of poly(acetic acid) (PHA) from acetic acid, while simultaneously maintaining growth. Therefore, the carbon-to-nitrogen ratio (C / N) and the carbon-to-phosphorus ratio (C / P) have always been important influencing indicators in biological nitrogen and phosphorus removal. In my country, the C / N ratio in wastewater has consistently remained at a low level. Currently, in actual wastewater treatment processes, the main solution for wastewater with a low C / N ratio is to add external carbon sources to the wastewater, which is insufficient in carbon. However, adding external carbon sources often increases costs, and excessive addition can easily cause secondary pollution.

[0004] In recent years, the global response to global warming and climate change has been driven by an increase in greenhouse gases in the environment. Due to the significant lag in the cascading effects of Earth's ecosystems, the crisis is only beginning to emerge; extreme weather events are becoming more frequent, intense, and unpredictable, making global warming inevitable. Traditional nitrogen and phosphorus biotechnology in the field of ecological environmental protection requires the addition of external carbon sources and phosphorus removal agents, mechanical aeration, and the discharge of large amounts of phosphorus-containing sludge, generating greenhouse gases such as CO2. Therefore, in terms of carbon reduction, reducing the use of external carbon sources or agents and lowering energy consumption in wastewater treatment processes is a widely accepted approach to promoting carbon reduction in wastewater treatment.

[0005] In view of this, scholars have developed a bacterial-algae symbiotic wastewater treatment process. In the bacterial-algae symbiotic system, heterotrophic bacteria utilize oxygen in the water to degrade organic matter, generating carbon dioxide, ammonium salts, nitrates, and water, which become raw materials for algae synthesis; the oxygen produced by microalgae during photosynthesis can meet the needs of bacterial life activities, and bacteria can also utilize intracellular nutrients by destroying the cell walls of microalgae. In these biochemical reactions, bacteria and algae promote and interact with each other, forming a bacterial-algae symbiotic system. However, the bacterial-algae symbiotic system currently has the following problems: (1) Within the same system, the growth rate of bacteria is fast, while the growth rate of algae is slow, and the bacterial-algae system is prone to imbalance; (2) It cannot treat nitrogen and phosphorus pollutants with high concentrations in the raw water; (3) The pollutant removal rate is low. Summary of the Invention

[0006] This invention provides a wastewater resource utilization nitrogen and phosphorus removal device and method without external carbon source. The process is simple, requires no chemical phosphorus removal agents, no external carbon source, no mechanical aeration, no discharge of excess sludge, and has near-zero carbon emissions.

[0007] The technical solution of the present invention is as follows:

[0008] A wastewater resource recovery nitrogen and phosphorus removal device without external carbon source includes an anaerobic (anoxic) reactor, an aerobic reactor, a sedimentation tank, and a photosynthetic algae reactor connected in sequence.

[0009] The anaerobic reactor includes a shell, an inlet pipe, a sludge inlet pipe, an outlet pipe, an anaerobic sludge layer, a stirrer, a return pipe, a ventilation pipe, and an outlet pipe. The anaerobic sludge layer is located inside the shell. The stirrer is located below the anaerobic sludge layer. The inlet pipe and the sludge inlet pipe are located at the lower part of the shell. The outlet pipe is located at the upper part of the shell. The ventilation pipe and the outlet pipe are located at the top of the shell. The return pipe is connected to the inlet pipe.

[0010] The aerobic reactor includes a shell 2, an aerobic sludge layer, an aeration pipe 1, an aeration disc 1, an outlet pipe 2, a gas pipeline booster pump 1, an inlet pipe 2, a return pipe 2, a ventilation pipe 2, an air outlet pipe 2, and a make-up air pipe. The aerobic sludge layer is located inside the shell 2. The aeration disc 1 is located below the aerobic sludge layer. The inlet pipe 2 and the aeration pipe 1 are located at the lower part of the shell 2. The outlet pipe 2 is located at the upper part of the shell 2. The ventilation pipe 2 and the air outlet pipe 2 are located at the top of the shell 2. The inlet pipe 2 is connected to the outlet pipe 1. The return pipe 2 is connected to the inlet pipe 2. The gas pipeline booster pump 1 is located on the aeration pipe 1. A make-up air pipe is provided between the gas pipeline booster pump 1 and the aeration pipe 1.

[0011] The sedimentation tank includes a shell (shell 3), an inlet pipe (shell 3), an outlet channel, an outlet pipe (shell 3), a sludge pump, a sludge discharge pipe (shell 1), a vent pipe (shell 3), and a central pipe. The outlet channel, sludge pump, and central pipe are located inside the shell (shell 3). The outlet channel is located at the upper part of the shell (shell 3), the sludge pump is located at the bottom of the shell (shell 3), and the central pipe is located at the center of the upper part of the shell (shell 3). The central pipe is connected to the outlet pipe (shell 2) through the inlet pipe (shell 3). The outlet pipe (shell 3) is located at the upper part of the shell (shell 3) and is connected to the outlet channel. The sludge discharge pipe (shell 1) is located at the bottom of the shell (shell 3) and is connected to the sludge pump. The vent pipe (shell 3) is located at the top of the shell (shell 3).

[0012] The photosynthetic algae reactor includes a shell (4), a photosynthetic algae layer, an inlet pipe (4), a sludge inlet pipe (2), an aeration pipe (2), an aeration disc (2), a gas pipeline booster pump (2), a sludge outlet pipe (2), an outlet pipe (4), an outlet pipe (3), a ventilation pipe (4), a return pump, a return pipe (3), and a light source. The photosynthetic algae layer is located inside the shell (4), the aeration disc (2) is located below the photosynthetic algae layer, the sludge inlet pipe (2), the inlet pipe (4), the aeration pipe (2), and the sludge outlet pipe (2) are located at the lower part of the shell (4), the outlet pipe (4) and the outlet pipe (3) are located at the upper part of the shell (4), the ventilation pipe (4) is located at the top of the shell (4), the gas pipeline booster pump (2) is located on the aeration pipe (2), the aeration pipe (2) is connected to both the outlet pipe (1) and the outlet pipe (2), the outlet pipe (3) is connected to the aeration pipe (1), one end of the return pipe (3) is connected to the outlet pipe (4), the return pump is located on the return pipe (3), and the other end of the return pipe (3) is connected to both the return pipe (1) and the return pipe (2), the sludge outlet pipe (1) is connected to both the inlet pipe (1) and the inlet pipe (2), and the light source is located above the shell (4).

[0013] Ventilation pipes 1, 2, 3 and 4 are connected to a main vent pipe, which is equipped with an exhaust valve and a pressure gauge.

[0014] Furthermore, in the aforementioned wastewater resource recovery nitrogen and phosphorus removal device without external carbon sources, the anaerobic (anoxic) sludge layer contains anaerobic sludge and / or anoxic sludge. The anaerobic sludge and anoxic sludge are first inoculated with mixed sludge, which includes municipal sludge and river sediment. The municipal sludge is taken from a municipal wastewater treatment plant, and the river sediment is taken from lakes and rivers where algae can be clearly observed. The mass ratio of municipal sludge to river sediment is 40% and 60%, respectively.

[0015] The anaerobic and anoxic sludge were suspended. After high-throughput sequencing, the microbial populations and abundances at the phylum level were Proteobacteria (25-40%), Planctomycetes (20-35%), Firmicutes (5-15%), and Bacteroidetes (5-10%). At the class level, the microbial populations and abundances were Alphaproteobacteria (15-30%), Planctomycetia (10-20%), Gammaproteobacteria (5-15%), and Saprospirae (1-10%).

[0016] Furthermore, in the aforementioned wastewater resource-based nitrogen and phosphorus removal device without external carbon sources, the aerobic sludge layer contains aerobic sludge. The aerobic sludge is first inoculated with a mixed ecological sludge of bacteria and algae. The mixed ecological sludge of bacteria and algae includes municipal sludge, river sediment, and algae. The municipal sludge is taken from a municipal wastewater treatment plant, and the river sediment is taken from lakes and rivers rich in algae. The algae are composed of Chlorella (50%) and Scenedesmus (50%). The mass ratios of municipal sludge, river sediment, and algae are 50%, 30%, and 20%, respectively.

[0017] The aerobic sludge was suspended. After high-throughput sequencing, the main microbial populations and abundances at the phylum level were Planctomycetes (30-40%), Proteobacteria (15-25%), Bacteroidetes (5-15%), and Verrucomicrobia (3-10%). At the class level, the main microbial populations and abundances were Planctomycetia (10-25%), Alphaproteobacteria (5-20%), Betaproteobacteria (5-15%), Sphingobacteriia (5-15%), Cytophagia (1-10%), and Verrucomicrobiae (1-10%).

[0018] Furthermore, in the aforementioned wastewater resource-based nitrogen and phosphorus removal device without external carbon sources, the photosynthetic algae layer includes photosynthetic algae mud, suspended packing material, and a fixing device. The photosynthetic algae mud is self-cultivated by light, the suspended packing material is set on the fixing device, and the photosynthetic algae mud is set on the suspended packing material.

[0019] Microalgae sequencing of photosynthetic algae mud revealed that the algae at the class level were Chlorophyceae, accounting for more than 30%.

[0020] Furthermore, the aforementioned wastewater resource-based nitrogen and phosphorus removal device without external carbon sources has an anaerobic (anoxic) reactor shell with a rectangular or cylindrical shape, a designed hydraulic retention time of 4-6 hours, and an MLSS of 5000-6000 mg / L; the stirrer has a designed power of 10-12 W / m³, which is frequency-adjustable; and the total height of the anaerobic (anoxic) reactor (A) is not less than 4 m.

[0021] The hydraulic retention time of the aerobic reactor is 12-16 hours; the height of the aerobic sludge layer is not less than 2 meters, and the total height of the aerobic reactor is not more than 4 meters; the MLSS is 3000-3500 mg / L; a frequency converter-adjustable pump is added to the gas pipeline.

[0022] The sedimentation tank is a vertical flow sedimentation tank, employing incomplete sedimentation with a sedimentation time T≤10min; the surface loading rate is 1.8-2.2m / h; the maximum reflux ratio of the sludge discharge pump is 500%, and it is frequency-adjustable.

[0023] The hydraulic retention time of the photosynthetic algae reactor is 18-24 hours; the light intensity is 3000 lux; the light conditions are 12 hours of bright light and 12 hours of dark light; the suspended packing material is a three-dimensional non-clogging PP packing material, made of modified polypropylene; the suspended packing material is sheet-shaped, square, with a side length of 10-15 cm and a thickness of 2-4 mm, and the edges of the suspended packing material are serrated; the suspended packing material is evenly distributed from top to bottom, the spacing between the supports of the fixing device is 20-25 cm, and the spacing between the upper and lower layers of suspended packing material is 15-20 cm; the number of layers of suspended packing material is 4-6; the total height of the photosynthetic algae reactor is no more than 3 m, and the SOGR (oxygen production per unit content of chlorophyll per unit time) of the algae is 50-60 μmol O2 mg. -1 Chla h -1 .

[0024] A wastewater resource-based nitrogen and phosphorus removal method without external carbon sources, utilizing the aforementioned wastewater resource-based nitrogen and phosphorus removal device without external carbon sources, includes the following steps:

[0025] (1) Before the anaerobic reactor is put into operation, mixed sludge is used for inoculation. The amount of mixed sludge added is 1 / 5 to 1 / 4 of the anaerobic reactor. The remaining part is filled with the sewage to be treated. Aeration is carried out continuously for 5 days, and then aeration is stopped. Water is continuously fed in and discharged until the required sludge concentration is reached. Then, high-throughput sequencing is carried out on the system. The population and abundance requirements at the phylum and class levels are met and the system can start normal operation.

[0026] (2) Before the aerobic reactor is put into operation, a mixed ecological sludge of bacteria and algae is used for inoculation. The amount of mixed ecological sludge of bacteria and algae is 1 / 5 to 1 / 4 of the aerobic reactor. The remaining part is filled with the sewage to be treated. The system continuously inlets and outlets the water and continuously aerates until the required sludge concentration is reached. Then, the system is subjected to high-throughput sequencing. The system starts to operate normally when the population and abundance requirements at the phylum and class levels are met.

[0027] (3) Before the photosynthetic algae reactor is put into operation, water is continuously fed in and out, and light is maintained for 12 hours and darkness for 12 hours. After the required algae SOGR is reached, microalgae sequencing is performed on the system. When the proportion of Chlorophyceae at the class level reaches more than 30%, it is considered that the domestication is successful and normal operation begins.

[0028] (4) The influent contains pollutants such as organic matter, nitrogen and phosphorus. It enters the anaerobic (anoxic) reactor through the influent pipe 1. Part of the effluent returns to the anaerobic (anoxic) reactor through the return pipe 3, return pump and return pipe 1. The sludge in the sedimentation tank returns to the anaerobic (anoxic) reactor through the sludge discharge pump, sludge discharge pipe 1 and sludge inlet pipe 1. The influent, return and sludge are mixed by the agitator. The organic matter, nitrogen and phosphorus in the influent are decomposed by the anaerobic sludge or anoxic sludge in the anaerobic (anoxic) sludge layer. After decomposition, H2, CO, CH4 and CO2 enter the photosynthetic algae reactor through the gas outlet pipe 1, aeration pipe 2 and aeration disc 2. The decomposed pollutants in the water enter the aerobic reactor with the effluent.

[0029] (5) The effluent from the anaerobic reactor enters the aerobic reactor. Part of the effluent from the photosynthetic algae reactor returns to the aerobic reactor via return pipe three, return pump, and return pipe two. The pollutants in the influent and return effluent are decomposed by the aerobic sludge in the aerobic sludge layer. After decomposition, part of it becomes H2, CO, CH4, CO2, N2, and H3P, which enter the photosynthetic algae reactor through air outlet pipe two, aeration pipe two, and aeration disc two. The decomposed pollutants in the water enter the sedimentation tank with the effluent.

[0030] (6) The effluent from the aerobic reactor enters the sedimentation tank, where the wastewater undergoes sludge-water separation. The remaining sludge is returned to the anaerobic (anoxic) reactor and the photosynthetic algae reactor through the sludge discharge pump and sludge discharge pipe according to the control requirements.

[0031] (7) The effluent from the sedimentation tank enters the photosynthetic algae reactor. The wastewater is decomposed by the photosynthetic algae sludge after passing through the photosynthetic algae layer. The effluent is directly discharged. The generated O2 gas enters the aerobic reactor through the three gas outlet pipes, the one aeration pipe, and the one aeration disc. The algae sludge is periodically discharged as biomass fuel.

[0032] Furthermore, in the aforementioned wastewater resource recovery method for nitrogen and phosphorus removal without external carbon sources, the effluent from the photosynthetic algae reactor does not flow back when the effluent meets the standards.

[0033] Furthermore, in the aforementioned wastewater resource recovery method for nitrogen and phosphorus removal without external carbon sources, when the effluent COD fails to meet the standard, the effluent pipe of the photosynthetic algae reactor is opened for reflux, and adjustments are made as follows:

[0034] ① If the exceedance is within 10%, 50% should be refluxed to the aerobic reactor;

[0035] ② If the exceedance is 10%-25%, 100% of the sample should be refluxed to the aerobic reactor;

[0036] ③ If the exceedance is 26%-50%, 200% is refluxed, 100% is returned to the aerobic reactor, and 100% is returned to the anaerobic (anoxic) reactor;

[0037] ④ If the concentration exceeds the standard by more than 50%, 300% should be refluxed to the anaerobic (anoxic) reactor;

[0038] When the nitrogen content of the effluent does not meet the standard, the effluent pipe 4 of the photosynthetic algae reactor will be opened for reflux. Adjustments should be made as follows:

[0039] 1) If the exceedance is within 10%, 50% should be recirculated to the anaerobic (anoxic) reactor;

[0040] 2) If the standard exceeds the limit by 10%-25%, 100% should be refluxed to the anaerobic (anoxic) reactor;

[0041] 3) If the exceedance is 26%-50%, reflux 200% to the anaerobic (anoxic) reactor;

[0042] 4) If the concentration exceeds the standard by more than 50%, 300% should be refluxed to the anaerobic (anoxic) reactor;

[0043] When the effluent P does not meet the standard, the sludge discharge pipe of the sedimentation tank is opened for backflow, and adjustments are made as follows:

[0044] a. If the exceedance is within 20%, 50% is recirculated to the anaerobic (anoxic) reactor;

[0045] b. If the exceedance is 20%-50%, 100% is refluxed to the anaerobic (anoxic) reactor;

[0046] c. If the standard is exceeded by more than 50%, 200% or 150% will be returned to the anaerobic (anoxic) reactor, and 50% will be returned to the photosynthetic algae reactor.

[0047] When both COD and N in the effluent fail to meet the standards, adjustments should be made according to the N non-compliance plan; when both COD and P in the effluent fail to meet the standards, adjustments should be made according to the P non-compliance plan; when both N and P in the effluent fail to meet the standards, adjustments should be made simultaneously according to both the N non-compliance plan and the P non-compliance plan.

[0048] Furthermore, in the aforementioned wastewater resource-based nitrogen and phosphorus removal method without external carbon sources, when the pressure gauge exceeds 1.0 MPa, the exhaust valve automatically opens to release the gas from the system.

[0049] The beneficial effects of this invention are as follows:

[0050] 1. This invention combines anaerobic / anoxic, aerobic and photosynthetic algae, with a simple process. Under normal operating conditions, through the exchange and circulation between gaseous, solid and liquid substances, it can achieve near-zero carbon emissions in the process of treating wastewater without the need for chemical phosphorus removal agents, external carbon sources, mechanical aeration, discharge of residual sludge.

[0051] 2. The hydraulic retention time and MLSS index of the anaerobic (anoxic) reactor of the present invention are lower than those of traditional anaerobic (anoxic) reactors, which can reduce the amount of sludge.

[0052] 3. The sedimentation tank of the present invention adopts incomplete sedimentation, with short sedimentation time, high surface load, and high reflux ratio, which can achieve the advantage of allowing part of the sludge to settle, while the unsettled part enters the photosynthetic algae reactor with the effluent as food for algae, thereby reducing the amount of sludge.

[0053] 4. The suspended packing material of the photosynthetic algae reactor of the present invention can overcome the problem of uneven lighting in traditional algae systems and save light sources.

[0054] 5. This invention targets nitrogen and phosphorus pollutants, and can treat nitrogen and phosphorus pollutants of various concentrations with excellent effluent quality. When the effluent quality is optimal, it can reach the Class III standard limit of the Surface Water Environmental Quality Standard (GB3838-2020).

[0055] 6. This invention sets up the bacteria and algae systems separately and uses them in combination, overcoming the problem of unbalanced growth of bacteria and algae in traditional bacteria-algae symbiotic systems.

[0056] 7. This invention not only reduces the addition of carbon sources, but also reduces energy consumption in aeration because the oxygen generated by the system dissolves in the wastewater. Attached Figure Description

[0057] Figure 1 A schematic diagram of a wastewater resource recovery and denitrification and phosphorus removal device without an external carbon source;

[0058] Figure 2 This is a diagram showing the distribution of bacterial communities at the phylum level in the anaerobic (anoxic) reactor of Example 1. "Prereaction" represents the initial inoculation state, while "Sample-1," "Sample-2," and "Sample-3" represent samples taken after reaching the required sludge concentration. Samples-1,-2, and-3 were taken from the upper, middle, and lower layers of the reactor, respectively.

[0059] Figure 3This is a diagram showing the distribution of bacterial communities at the class level in the anaerobic (anoxic) reactor of Example 1. Prereaction refers to the time immediately after inoculation, while Sample-1, Sample-2, and Sample-3 are samples taken after the required sludge concentration has been reached. Sample-1, Sample-2, and Sample-3 were taken from the upper, middle, and lower layers of the reactor, respectively.

[0060] Figure 4 This is a diagram showing the distribution of bacterial communities at the phylum level in the aerobic reactor of Example 1. Prereaction refers to the time immediately after inoculation, while Sample-1, Sample-2, and Sample-3 are samples taken after the required sludge concentration has been reached. Sample-1, Sample-2, and Sample-3 were taken from the upper, middle, and lower layers of the reactor, respectively.

[0061] Figure 5 This is a diagram showing the distribution of bacterial communities at the class level in the aerobic reactor of Example 1. Prereaction refers to the time immediately after inoculation, while Sample-1, Sample-2, and Sample-3 are samples taken after the required sludge concentration has been reached. Sample-1, Sample-2, and Sample-3 were taken from the upper, middle, and lower layers of the reactor, respectively.

[0062] Figure 6 This is a diagram showing the distribution of bacterial communities at the phylum level in the anaerobic (anoxic) reactor of Example 2. Prereaction refers to the time immediately after inoculation, while Sample-1, Sample-2, and Sample-3 are samples taken after the required sludge concentration has been reached. Sample-1, Sample-2, and Sample-3 were taken from the upper, middle, and lower layers of the reactor, respectively.

[0063] Figure 7 This is a diagram showing the distribution of bacterial communities at the class level in the anaerobic (anoxic) reactor of Example 2. Prereaction refers to the time immediately after inoculation, while Sample-1, Sample-2, and Sample-3 are samples taken after the required sludge concentration has been reached. Sample-1, Sample-2, and Sample-3 were taken from the upper, middle, and lower layers of the reactor, respectively.

[0064] Figure 8 This is a diagram showing the distribution of bacterial communities at the phylum level in the aerobic reactor of Example 2. Prereaction refers to the time immediately after inoculation, while Sample-1, Sample-2, and Sample-3 are samples taken after the required sludge concentration has been reached. Sample-1, Sample-2, and Sample-3 were taken from the upper, middle, and lower layers of the reactor, respectively.

[0065] Figure 9This is a diagram showing the distribution of bacterial communities at the class level in the aerobic reactor of Example 2. Prereaction refers to the time immediately after inoculation, while Sample-1, Sample-2, and Sample-3 are samples taken after the required sludge concentration has been reached. Sample-1, Sample-2, and Sample-3 were taken from the upper, middle, and lower layers of the reactor, respectively. Detailed Implementation

[0066] like Figure 1 As shown, a wastewater resource recovery nitrogen and phosphorus removal device without external carbon source includes an anaerobic (anoxic) reactor, an aerobic reactor, a sedimentation tank, and a photosynthetic algae reactor connected in sequence.

[0067] The anaerobic reactor includes a shell, an inlet pipe 1, a sludge inlet pipe 2, an outlet pipe 3, an anaerobic sludge layer 4, a stirrer 5, a return pipe 6, a vent pipe 7, and an outlet pipe 8. The anaerobic sludge layer 4 is located inside the shell. The stirrer 5 is located below the anaerobic sludge layer 4. The inlet pipe 1 and the sludge inlet pipe 2 are located at the lower part of the shell. The outlet pipe 3 is located at the upper part of the shell. The vent pipe 7 and the outlet pipe 8 are located at the top of the shell. The return pipe 6 is connected to the inlet pipe 1.

[0068] The shell of the anaerobic reactor is cylindrical, with a designed hydraulic retention time of 4-6 hours and a MLSS of 5000-6000 mg / L; the stirrer 5 has a designed power of 10-12 W / m³ and is frequency-adjustable; the total height of the anaerobic reactor (A) is not less than 4 m.

[0069] Anaerobic (anoxic) sludge layer 4 contains anaerobic sludge and / or anoxic sludge. The anaerobic and anoxic sludge are inoculated with mixed sludge, which includes municipal sludge and river sediment. The municipal sludge is taken from municipal wastewater treatment plants, and the river sediment is taken from lakes and rivers where algae are clearly observed. The mass ratio of municipal sludge to river sediment is 40% and 60%, respectively. The anaerobic and anoxic sludge is suspended. After high-throughput sequencing, the microbial population and abundance at the phylum level are Proteobacteria (25-40%), Planctomycetes (20-35%), Firmicutes (5-15%), and Bacteroidetes (5-10%). The microbial population and abundance at the class level are Alphaproteobacteria (15-30%), Planctomycetia (10-20%), Gammaproteobacteria (5-15%), and Saprospirae (1-10%).

[0070] The aerobic reactor includes a shell, an aerobic sludge layer 9, an aeration pipe 10, an aeration disc 11, an outlet pipe 12, a gas pipeline booster pump 13, an inlet pipe 14, a return pipe 15, a ventilation pipe 16, an air outlet pipe 17, and a make-up air pipe 18. The aerobic sludge layer 9 is located inside the shell. The aeration disc 11 is located below the aerobic sludge layer 9. The inlet pipe 14 and the aeration pipe 10 are located at the lower part of the shell. The outlet pipe 12 is located at the upper part of the shell. The ventilation pipe 16 and the air outlet pipe 17 are located at the top of the shell. The inlet pipe 14 is connected to the outlet pipe 13. The return pipe 15 is connected to the inlet pipe 14. The gas pipeline booster pump 13 is located on the aeration pipe 10. A make-up air pipe 18 is provided between the gas pipeline booster pump 13 and the aeration pipe 10.

[0071] The hydraulic retention time of the aerobic reactor is 12-16 hours; the height of the aerobic sludge layer 9 is not less than 2 meters, and the total height of the aerobic reactor is not greater than 4 meters; the MLSS is 3000-3500 mg / L; the gas pipeline is equipped with a frequency-adjustable pump 13.

[0072] Aerobic sludge layer 9 contains aerobic sludge, which is initially inoculated using a mixed microbial-algae ecological sludge. This mixed microbial-algae ecological sludge includes municipal sludge, river sediment, and algae. The municipal sludge is taken from a municipal wastewater treatment plant, and the river sediment is taken from lakes and rivers rich in algae. The algae consist of Chlorella (50%) and Scenedesmus (50%). The mass ratios of municipal sludge, river sediment, and algae are 50%, 30%, and 20%, respectively. The aerobic sludge is suspended. High-throughput sequencing revealed that the main microbial populations and abundances at the phylum level were Planctomycetes (30-40%) and Proteobacteria. (15-25%), Bacteroidetes (5-15%), Verrucomicrobia (3-10%). The main microbial populations and abundances at the class level are Planctomycetia (10-25%), Alphaproteobacteria (5-20%), Betaproteobacteria (5-15%), Sphingobacteriia (5-15%), Cytophagia (1-10%), and Verrucomicrobiae (1-10%).

[0073] The sedimentation tank includes a shell (shell 3), an inlet pipe (3) 19, an outlet channel (20), an outlet pipe (3) 21, a sludge pump (22), a sludge discharge pipe (1) 23, a vent pipe (3) 24, and a central pipe (25). The outlet channel (20), sludge pump (22), and central pipe (25) are located inside the shell (shell 3). The outlet channel (20) is located at the upper part of the shell (shell 3), the sludge pump (22) is located at the bottom of the shell (shell 3), and the central pipe (25) is located at the center of the upper part of the shell (shell 3). The central pipe (25) is connected to the outlet pipe (2) 12 through the inlet pipe (3) 19. The outlet pipe (3) 21 is located at the upper part of the shell (shell 3) and is connected to the outlet channel (20). The sludge discharge pipe (1) 23 is located at the bottom of the shell (shell 3) and is connected to the sludge pump (22). The vent pipe (3) 24 is located at the top of the shell (shell 3). The sedimentation tank is a vertical flow sedimentation tank, using incomplete sedimentation, with a sedimentation time T ≤ 10 min. The surface loading rate is 1.8-2.2 m / h. The sludge pump (22) has a maximum reflux ratio of 500% and is frequency-adjustable.

[0074] The photosynthetic algae reactor includes a shell (4), a photosynthetic algae layer (35), an inlet pipe (4) (26), a sludge inlet pipe (20), an aeration pipe (27), an aeration disc (28), a gas pipeline booster pump (29), a sludge outlet pipe (21), an inlet pipe (42), an outlet pipe (33), a ventilation pipe (44), a return pump (36), a return pipe (37), and a light source (30). The photosynthetic algae layer (35) is located inside the shell (4), and the aeration disc (28) is located below the photosynthetic algae layer (35). The sludge inlet pipe (24), inlet pipe (46), aeration pipe (27), and sludge outlet pipe (21) are located in the lower part of the shell (4), and the inlet pipe (42) and outlet pipe (33) are located in the lower part of the shell (4). The following components are installed on the upper part of the shell: Ventilation pipe 34 is located at the top of the shell; Gas pipeline pump 29 is installed on aeration pipe 27; Aeration pipe 27 is connected to outlet pipe 8 and outlet pipe 17 respectively; Outlet pipe 33 is connected to aeration pipe 10; One end of return pipe 37 is connected to water outlet pipe 32; Return pump 36 is installed on return pipe 37; The other end of return pipe 37 is connected to return pipe 6 and return pipe 15; Sludge outlet pipe 23 is connected to sludge inlet pipe 2 and sludge inlet pipe 40 respectively; The light source 30 is located above the shell.

[0075] The photosynthetic algae layer 35 includes photosynthetic algae mud, suspended packing material, and a fixing device. The photosynthetic algae mud is self-cultivated under light, the suspended packing material is placed on the fixing device, and the photosynthetic algae mud is placed on the suspended packing material. Microalgae sequencing was performed on the photosynthetic algae mud, and the algae at the class level in the system are Chlorophyceae, accounting for more than 30%.

[0076] The hydraulic retention time of the photosynthetic algae reactor is 18-24 hours; the light intensity is 3000 lux; the light conditions are 12 hours of bright light and 12 hours of dark light; the suspended packing material is a three-dimensional non-clogging PP packing material, made of modified polypropylene; the suspended packing material is sheet-shaped, square, with a side length of 10-15 cm and a thickness of 2-4 mm, and the edges of the suspended packing material are serrated; the suspended packing material is evenly distributed from top to bottom, the spacing between the supports of the fixing device is 20-25 cm, and the spacing between the upper and lower layers of suspended packing material is 15-20 cm; the number of layers of suspended packing material is 4-6; the total height of the photosynthetic algae reactor is no more than 3 m, and the SOGR (oxygen production per unit content of chlorophyll per unit time) of the algae is 50-60 μmol O2 mg. -1 Chla h -1 .

[0077] Ventilation pipe 1 (7), ventilation pipe 2 (16), ventilation pipe 3 (24), and ventilation pipe 4 (34) are connected to a main ventilation pipe, which is equipped with an exhaust valve (38) and a pressure gauge (39). Example

[0078] Wastewater from a certain industry has the following indices: COD = 100 mg / L, ammonia nitrogen = 50 mg / L, TN = 70 mg / L, TP = 10 mg / L.

[0079] The anaerobic (anoxic) reactor is designed with a hydraulic retention time of 4 hours; MLSS of 5000 mg / L; agitator 5 is designed with a power of 10 W / m³, adjustable by frequency conversion; and the total height of the anaerobic (anoxic) reactor is 4.5 m.

[0080] The hydraulic retention time of the aerobic reactor is 12 hours; the height of the aerobic sludge layer 9 is 2.5 meters, and the total height of the aerobic reactor is 3.5 meters; the MLSS is 3000 mg / L; and a variable frequency adjustable pump 13 is added to the gas pipeline.

[0081] The sedimentation tank is a vertical flow sedimentation tank, using incomplete sedimentation, with a sedimentation time T=10min; the surface loading rate is 2.0m / h; the sludge pump 22 has a maximum reflux ratio of 200% and is frequency-adjustable.

[0082] The hydraulic retention time of the photosynthetic algae reactor is 18 hours; the light intensity is 3000 lux; the light conditions are 12 hours of bright light and 12 hours of dark light; the packing material is three-dimensional non-clogging PP packing material, which is modified polypropylene; the packing size is 10 cm; the spacing between packing materials is 20 cm; the spacing between the upper and lower layers of packing materials is 15 cm; the number of packing layers is 4; the total height of the photosynthetic algae reactor is 2.6 m; the algal SOGR (oxygen production per unit chlorophyll per unit time) is 50 μmol O2 mg. -1 Chla h -1 .

[0083] like Figure 2-5 As shown, a wastewater resource-based nitrogen and phosphorus removal method without external carbon sources includes the following steps:

[0084] (1) Before the anaerobic reactor is put into formal operation, mixed sludge is used for inoculation. The amount of mixed sludge added is 1 / 5 of the anaerobic reactor, and the remaining part is filled with the sewage to be treated. Aeration is carried out continuously for 5 days, then aeration is stopped, and water is continuously fed and discharged until the required sludge concentration is reached. High-throughput sequencing is performed on the system. The main microbial populations and abundances at the phylum level are Proteobacteria (30.5-37.2%), Planctomycetes (24.3-27.3%), and Fir The abundance of microbial species at the class level was 7.2-9.5% and 5.7-6.8%, with Alphaproteobacteria (19.4-23.8%), Planctomycetia (17.1-19.5%), Gammaproteobacteria (9.8-11.1%), and Saprospirae (7.7-9.4%). This indicates successful domestication and the system has begun normal operation.

[0085] (2) Before the aerobic reactor was put into operation, a mixed ecological sludge of bacteria and algae was used for inoculation. The amount of mixed ecological sludge added was 1 / 5 of the aerobic reactor, and the remaining part was filled with the sewage to be treated. Continuous influent and effluent were introduced, and continuous aeration was carried out until the required sludge concentration was reached. High-throughput sequencing was then performed on the system. The main microbial populations and abundances at the phylum level of the system were Planctomycetes (33.3-36.0%), Proteobacteria (17.2-20.3%), Bacteroidetes (9.8-11.1%), and Verrucomicrobial community. The abundance of microbial species at the class level was 5.5-7.5%, with Planctomycetia (15.2-18.5%), Alphaproteobacteria (13.9-15.5%), Betaproteobacteria (7.5-9.8%), Sphingobacteriia (7.2-8.8%), Cytophagia (3.3-4.5%), and Verrucomicrobiae (3.7-4.7%), indicating successful domestication and the system has begun normal operation.

[0086] (3) Before the photosynthetic algae reactor is put into operation, water is continuously fed in and out, and the light is maintained for 12 hours and the darkness for 12 hours. After the required algae SOGR is reached, microalgae sequencing is performed on the system. At the class level, the proportion of Chlorophyceae reaches 33%, indicating that the domestication is successful and normal operation begins.

[0087] (4) The influent contains pollutants such as organic matter, nitrogen and phosphorus, which enter the anaerobic (anoxic) reactor through the influent pipe 1. Part of the effluent returns to the anaerobic (anoxic) reactor through the return pipe 37, return pump 36 and return pipe 6. The sludge in the sedimentation tank returns to the anaerobic (anoxic) reactor through the sludge discharge pump 22, sludge discharge pipe 23 and sludge inlet pipe 2. The influent, return and sludge are mixed by the agitator 5. The pollutants such as organic matter, nitrogen and phosphorus in the influent are decomposed by the anaerobic sludge or anoxic sludge in the anaerobic (anoxic) sludge layer 4. After decomposition, H2, CO, CH4 and CO2 enter the photosynthetic algae reactor through the air outlet pipe 8, aeration pipe 27 and aeration disc 28. The decomposed pollutants in the water enter the aerobic reactor with the effluent.

[0088] (5) The effluent from the anaerobic reactor enters the aerobic reactor. Part of the effluent from the photosynthetic algae reactor returns to the aerobic reactor via return pipe 37, return pump 36, and return pipe 215. The pollutants in the influent and return effluent are decomposed by the aerobic sludge in the aerobic sludge layer. After decomposition, part of it becomes H2, CO, CH4, CO2, N2, and H3P, which enter the photosynthetic algae reactor through the air outlet pipe 217, aeration pipe 27, and aeration disc 28. The decomposed pollutants in the water enter the sedimentation tank with the effluent.

[0089] (6) The effluent from the aerobic reactor enters the sedimentation tank, where the wastewater undergoes sludge-water separation. The remaining sludge is returned to the anaerobic (anoxic) reactor and the photosynthetic algae reactor through the sludge discharge pump 22 and the sludge discharge pipe 23 according to the control requirements.

[0090] (7) The effluent from the sedimentation tank enters the photosynthetic algae reactor. The wastewater is decomposed by the photosynthetic algae mud after passing through the photosynthetic algae layer. The effluent is directly discharged. The generated O2 gas enters the aerobic reactor through the gas outlet pipe 33, aeration pipe 10, and aeration disc 11. The algae mud is periodically discharged as biomass fuel.

[0091] (8) The entire normal treatment process lasts for 30 days. From day 1 to day 9, the PLC system automatically starts the effluent circulation, and the effluent pipe 4.32 of the photosynthetic algae reactor starts the recirculation, with 200% recirculation to the anaerobic (anoxic) reactor; from day 10 to day 17, the PLC system automatically starts the effluent circulation, and the effluent pipe 4.32 of the photosynthetic algae reactor starts the recirculation, with 100% recirculation to the anaerobic (anoxic) reactor; from day 18 to day 21, the PLC system automatically starts the effluent circulation, and the effluent pipe 4.32 of the photosynthetic algae reactor starts the recirculation, with 50% recirculation to the anaerobic (anoxic) reactor.

[0092] (9) The entire normal treatment process lasted 30 days, during which the anaerobic (anoxic) reactor was in an anaerobic state; during this period, the gas pipeline added pump 29, the gas pipeline added pump 13, and the exhaust valve 38 were not opened;

[0093] (10) The effluent indicators meet the Class III standard limits of the Surface Water Environmental Quality Standard (GB3838-2020) (COD<20mg / L, ammonia nitrogen<1.0mg / L, TN<1.0mg / L, TP<0.2mg / L). The pollutant removal rates are shown in Table 1.

[0094] Table 1 Pollutant Removal Rate Table

[0095] project unit COD ammonia nitrogen TN TP Water ingress mg / L 100 50 70 10 Out of water mg / L 20 1 1 1.2 Removal rate % 80.00% 98.00% 98.57% 98.00% Example

[0096] Wastewater from a certain industry has the following indices: COD = 620 mg / L, ammonia nitrogen = 30 mg / L, TN = 150 mg / L, TP = 30 mg / L.

[0097] The anaerobic (anoxic) reactor is designed with a hydraulic retention time of 6 hours; MLSS is 5500 mg / L; the stirrer 5 is designed with a power of 12 W / m³, which is frequency-adjustable; the total height of the anaerobic (anoxic) reactor is 7.5 m.

[0098] The hydraulic retention time of the aerobic reactor is 16 hours; the height of the aerobic sludge layer 9 is 3 meters, and the total height of the aerobic reactor is 4 meters; the MLSS is 3500 mg / L; and a variable frequency adjustable pump 13 is added to the gas pipeline.

[0099] The sedimentation tank is a vertical flow sedimentation tank, using incomplete sedimentation, with a sedimentation time T=10min; the surface loading rate is 1.9m / h; the sludge pump 22 has a maximum reflux ratio of 500% and is frequency-adjustable.

[0100] The hydraulic retention time of the photosynthetic algae reactor is 24 hours; the light intensity is 3000 lux; the light conditions are 12 hours of bright light and 12 hours of dark light; the packing material is three-dimensional non-clogging PP packing material, and the material is modified polypropylene; the packing size is 10 cm; the spacing between packing materials is 25 cm; the spacing between the upper and lower layers of packing materials is 20 cm; the number of packing layers is 6; the total height of the photosynthetic algae reactor is 3 m; the algal SOGR (oxygen production per unit chlorophyll per unit time) is 60 μmol O2 mg. -1 Chla h -1 .

[0101] like Figure 6-9 As shown, a wastewater resource-based nitrogen and phosphorus removal method without external carbon sources includes the following steps:

[0102] (1) Before the anaerobic reactor is put into formal operation, mixed sludge is used for inoculation. The amount of mixed sludge added is 1 / 4 of the anaerobic reactor, and the remaining part is filled with the sewage to be treated. Aeration is carried out continuously for 5 days, and then aeration is stopped. Water is continuously fed and discharged until the required sludge concentration is reached. The main microbial populations and abundances at the phylum level of the system are Proteobacteria (27.5-28.8%), Planctomycetes (25.3-28.2%), Firmicutes (25.3-28.2%), and Firmicutes (25.3-28.2%). The abundance of microbial species at the class level was 9.5-11.2% and Bacteroidetes (5.5-7.1%). The main microbial populations and abundances at the class level were Alphaproteobacteria (20.4-25.5%), Planctomycetia (15.5-18.8%), Gammaproteobacteria (8.8-10.1%), and Saprospirae (6.6-8.1%), indicating successful domestication and the start of normal operation.

[0103] (2) Before the aerobic reactor was put into operation, a mixed ecological sludge of bacteria and algae was used for inoculation. The amount of mixed ecological sludge added was 1 / 4 of the aerobic reactor, and the remaining part was filled with the sewage to be treated. Continuous influent and effluent were introduced, and continuous aeration was carried out until the required sludge concentration was reached. High-throughput sequencing was then performed on the system. The main microbial populations and abundances at the phylum level were Planctomycetes (30.8-34.4%), Proteobacteria (18.2-21.1%), Bacteroidetes (9.8-12.3%), and Verrucomicrobial community. The abundance of microbial species at the class level was 5.5-7.5%, with Planctomycetia (15.5-17.5%), Alphaproteobacteria (10.8-13.4%), Betaproteobacteria (9.7-11.9%), Sphingobacteriia (6.6-8.1%), Cytophagia (2.5-4.2%), and Verrucomicrobiae (3.4-4.8%), indicating successful domestication and the system has begun normal operation.

[0104] (3) Before the photosynthetic algae reactor is put into operation, water is continuously fed in and out, and light is maintained for 12 hours and darkness for 12 hours. After the required SOGR of algae is reached, microalgae sequencing is performed on the system. At the class level, the proportion of Chlorophyceae reaches 36%, indicating that the domestication is successful and normal operation begins.

[0105] (4) The influent contains pollutants such as organic matter, nitrogen and phosphorus, which enter the anaerobic (anoxic) reactor through the influent pipe 1. Part of the effluent returns to the anaerobic (anoxic) reactor through the return pipe 37, return pump 36 and return pipe 6. The sludge in the sedimentation tank returns to the anaerobic (anoxic) reactor through the sludge discharge pump 22, sludge discharge pipe 23 and sludge inlet pipe 2. The influent, return and sludge are mixed by the agitator 5. The organic matter, nitrogen and phosphorus in the influent are decomposed by the anaerobic sludge or anoxic sludge in the anaerobic (anoxic) sludge layer. After decomposition, H2, CO, CH4 and CO2 enter the photosynthetic algae reactor through the gas outlet pipe 8, aeration pipe 27 and aeration disc 28. The decomposed pollutants in the water enter the aerobic reactor with the effluent.

[0106] (5) The effluent from the anaerobic reactor enters the aerobic reactor. Part of the effluent from the photosynthetic algae reactor returns to the aerobic reactor via return pipe 37, return pump 36, and return pipe 215. The pollutants in the influent and return effluent are decomposed by the aerobic sludge in the aerobic sludge layer. After decomposition, part of it becomes H2, CO, CH4, CO2, N2, and H3P, which enter the photosynthetic algae reactor through the air outlet pipe 217, aeration pipe 27, and aeration disc 28. The decomposed pollutants in the water enter the sedimentation tank with the effluent.

[0107] (6) The effluent from the aerobic reactor enters the sedimentation tank, where the wastewater undergoes sludge-water separation. The remaining sludge is returned to the anaerobic (anoxic) reactor and the photosynthetic algae reactor through the sludge discharge pump 22 and the sludge discharge pipe 23 according to the control requirements.

[0108] (7) The effluent from the sedimentation tank enters the photosynthetic algae reactor. The wastewater is decomposed by the photosynthetic algae mud after passing through the photosynthetic algae layer. The effluent is directly discharged. The generated O2 gas enters the aerobic reactor through the gas outlet pipe 33, aeration pipe 10, and aeration disc 11. The algae mud is periodically discharged as biomass fuel.

[0109] (8) The entire normal treatment process lasts 60 days. From day 1 to day 16, the PLC system automatically starts the effluent circulation. The effluent pipe 32 of the photosynthetic algae reactor starts the recirculation, with 300% recirculated to the anaerobic (anoxic) reactor. From day 1 to day 9, the sludge pipe 23 of the sedimentation tank starts the recirculation, with 200% recirculated, 150% recirculated to the anaerobic (anoxic) reactor, and 50% recirculated to the photosynthetic algae reactor. From day 10 to day 16, the sludge pipe 23 of the sedimentation tank starts the recirculation, with 100% recirculated to the anaerobic (anoxic) reactor. From day 7 to day 22, 200% of the effluent from pipe 42 of the photosynthetic algae reactor was recirculated to the anaerobic (anoxic) reactor. At the same time, 50% of the sludge from pipe 42 of the sedimentation tank was recirculated to the anaerobic (anoxic) reactor. From day 23 to day 25, 200% of the effluent from pipe 42 of the photosynthetic algae reactor was recirculated to the aerobic reactor, and 100% to the anaerobic (anoxic) reactor (A). From day 26 to day 55, 50% of the effluent from pipe 42 of the photosynthetic algae reactor was recirculated to the anaerobic (anoxic) reactor. From day 56 to day 60, no recirculation was performed.

[0110] (9) The entire normal treatment process lasted 60 days. The anaerobic reactor was in anoxic state from day 1 to day 24, and in anaerobic state for the rest of the time. During this period, the gas pipeline added pump 29 was opened once on day 12 and day 16, the gas pipeline added pump 13 and gas supply pipe 18 were opened once on day 12 and day 16, and the exhaust valve 38 was opened once on day 36 and day 52.

[0111] (10) The effluent indicators meet the Class V standard limits of the Surface Water Environmental Quality Standard (GB3838-2020) (COD<40mg / L, ammonia nitrogen<2.0mg / L, TN<2.0mg / L, TP<0.4mg / L). The pollutant removal rates are shown in Table 2.

[0112] Table 2 Pollutant Removal Rate Table

[0113] project unit COD ammonia nitrogen TN TP Water ingress mg / L 620 30 150 30 Out of water mg / L 40 2 2 0.4 Removal rate % 93.55% 93.33% 98.67% 98.67%

Claims

1. A wastewater resource-based nitrogen and phosphorus removal method without external carbon sources, comprising an anaerobic reactor, an aerobic reactor, a sedimentation tank, and a photosynthetic algae reactor connected in sequence, characterized in that, The anaerobic reactor includes a shell, an inlet pipe, a sludge inlet pipe, an outlet pipe, an anaerobic sludge layer, a stirrer, a return pipe, an aeration pipe, and an outlet pipe. The anaerobic sludge layer is located inside the shell. The stirrer is located below the anaerobic sludge layer. The inlet pipe and the sludge inlet pipe are located at the lower part of the shell. The outlet pipe is located at the upper part of the shell. The aeration pipe and the outlet pipe are located at the top of the shell. The return pipe is connected to the inlet pipe. The aerobic reactor includes a shell 2, an aerobic sludge layer, an aeration pipe 1, an aeration disc 1, an outlet pipe 2, a gas pipeline booster pump 1, an inlet pipe 2, a return pipe 2, a ventilation pipe 2, an air outlet pipe 2, and a make-up air pipe. The aerobic sludge layer is located inside the shell 2. The aeration disc 1 is located below the aerobic sludge layer. The inlet pipe 2 and the aeration pipe 1 are located at the lower part of the shell 2. The outlet pipe 2 is located at the upper part of the shell 2. The ventilation pipe 2 and the air outlet pipe 2 are located at the top of the shell 2. The inlet pipe 2 is connected to the outlet pipe 1. The return pipe 2 is connected to the inlet pipe 2. The gas pipeline booster pump 1 is located on the aeration pipe 1. A make-up air pipe is provided between the gas pipeline booster pump 1 and the aeration pipe 1. The sedimentation tank includes a shell (shell 3), an inlet pipe (shell 3), an outlet channel, an outlet pipe (shell 3), a sludge pump, a sludge discharge pipe (shell 1), a vent pipe (shell 3), and a central pipe. The outlet channel, sludge pump, and central pipe are located inside the shell (shell 3). The outlet channel is located at the upper part of the shell (shell 3), the sludge pump is located at the bottom of the shell (shell 3), and the central pipe is located at the center of the upper part of the shell (shell 3). The central pipe is connected to the outlet pipe (shell 2) through the inlet pipe (shell 3). The outlet pipe (shell 3) is located at the upper part of the shell (shell 3) and is connected to the outlet channel. The sludge discharge pipe (shell 1) is located at the bottom of the shell (shell 3) and is connected to the sludge pump. The vent pipe (shell 3) is located at the top of the shell (shell 3). The photosynthetic algae reactor includes a shell (4), a photosynthetic algae layer, an inlet pipe (4), a sludge inlet pipe (2), an aeration pipe (2), an aeration disc (2), a gas pipeline booster pump (2), a sludge outlet pipe (2), an outlet pipe (4), an outlet pipe (3), a ventilation pipe (4), a return pump, a return pipe (3), and a light source. The photosynthetic algae layer is located inside the shell (4), the aeration disc (2) is located below the photosynthetic algae layer, the sludge inlet pipe (2), the inlet pipe (4), the aeration pipe (2), and the sludge outlet pipe (2) are located at the lower part of the shell (4), the outlet pipe (4) and the outlet pipe (3) are located at the upper part of the shell (4), the ventilation pipe (4) is located at the top of the shell (4), the gas pipeline booster pump (2) is located on the aeration pipe (2), the aeration pipe (2) is connected to both the outlet pipe (1) and the outlet pipe (2), the outlet pipe (3) is connected to the aeration pipe (1), one end of the return pipe (3) is connected to the outlet pipe (4), the return pump is located on the return pipe (3), and the other end of the return pipe (3) is connected to both the return pipe (1) and the return pipe (2), the sludge outlet pipe (1) is connected to both the inlet pipe (1) and the inlet pipe (2), and the light source is located above the shell (4). Ventilation pipe 1, ventilation pipe 2, ventilation pipe 3 and ventilation pipe 4 are connected to a main ventilation pipe, which is equipped with an exhaust valve and a pressure gauge. The shell of the anaerobic reactor is rectangular or cylindrical, with a designed hydraulic retention time of 4-6 hours and a MLSS of 5000-6000 mg / L. The agitator is designed with a power density of 10-12 W / m³ and is frequency-adjustable. The total height of the anaerobic reactor is not less than 4 m. The hydraulic retention time of the aerobic reactor is 12-16 hours; the height of the aerobic sludge layer is not less than 2 meters, and the total height of the aerobic reactor is not greater than 4 meters; the MLSS is 3000-3500 mg / L; a variable frequency pump is added to the gas pipeline; the aerobic sludge layer contains aerobic sludge, which is first inoculated with a mixture of bacteria and algae; O2 enters the aerobic reactor through the third gas outlet pipe, the first aeration pipe, and the first aeration disc. The sedimentation tank is a vertical flow sedimentation tank, employing incomplete sedimentation with a sedimentation time T≤10min; the surface loading rate is 1.8-2.2m / h; the maximum reflux ratio of the sludge discharge pump is 500%, and it is frequency-adjustable. The hydraulic retention time of the photosynthetic algae reactor is 18-24 hours; the light intensity is 3000 ppm. The light conditions are 12 hours of light and 12 hours of darkness. Gases produced from anaerobic sludge decomposition enter the photosynthetic algae reactor through outlet pipe 1, aeration pipe 2, and aeration disc 2. Gases produced from aerobic sludge decomposition also enter the reactor through outlet pipe 2, aeration pipe 2, and aeration disc 2. The photosynthetic algae layer consists of photosynthetic algae sludge, suspended packing, and fixing devices. The suspended packing is placed on the fixing devices, and the photosynthetic algae sludge is placed on the suspended packing. The suspended packing is a three-dimensional, non-clogging material made of modified polypropylene. It is sheet-shaped, square, with sides of 10-15 cm and a thickness of 2-4 mm, with serrated edges. The suspended packing is evenly distributed from top to bottom. The spacing between the fixing device supports is 20-25 cm, and the spacing between upper and lower layers of suspended packing is 15-20 cm. The number of suspended packing layers is 4-6. The total height of the photosynthetic algae reactor is no more than 3 m, and the SOGR of the algae is 50-60 μmol O2 mg. - 1 Chla h -1 .

2. The wastewater resource recovery method for nitrogen and phosphorus removal without external carbon source as described in claim 1, characterized in that, Anaerobic sludge is first inoculated with mixed sludge, which includes municipal sludge and river sediment. The municipal sludge is taken from municipal wastewater treatment plants, and the river sediment is taken from lakes and rivers where algae can be clearly observed. The mass ratio of municipal sludge and river sediment is 40% and 60%, respectively. The anaerobic sludge was suspended. High-throughput sequencing revealed the following major microbial populations and abundances at the phylum level: Proteobacteria 25-40%, Planctomycetes 20-35%, Firmicutes 5-15%, Bacteroidetes 5-10%; and at the class level: Alphaproteobacteria 15-30%, Planctomycetia 10-20%, Gammaproteobacteria 5-15%, Saprospirae 1-10%.

3. The wastewater resource recovery method for nitrogen and phosphorus removal without external carbon source as described in claim 1, characterized in that, The mixed ecological sludge of bacteria and algae includes municipal sludge, river sediment, and algae. The municipal sludge is taken from municipal sewage treatment plants, and the river sediment is taken from lakes and rivers rich in algae. The algae are composed of Chlorella and Scenedesmus. The mass ratio of municipal sludge, river sediment, and algae is 50%, 30%, and 20%, respectively. The aerobic sludge was suspended. High-throughput sequencing revealed the following major microbial populations and abundances at the phylum level: Planctomycetes 30-40%, Proteobacteria 15-25%, Bacteroidetes 5-15%, Verrucomicrobia 3-10%; and at the class level: Planctomycetia 10-25%, Alphaproteobacteria 5-20%, Betaproteobacteria 5-15%, Sphingobacteriia 5-15%, Cytophagia 1-10%, Verrucomicrobiae 1-10%.

4. The wastewater resource recovery method for nitrogen and phosphorus removal without external carbon source as described in claim 1, characterized in that, Microalgae sequencing of photosynthetic algae mud revealed that the algae at the class level were Chlorophyceae, accounting for more than 30%.

5. The wastewater resource utilization method for nitrogen and phosphorus removal without external carbon source according to claim 1, characterized in that, Includes the following steps: (1) Before the anaerobic reactor is put into operation, mixed sludge is used for inoculation. The amount of mixed sludge added is 1 / 5 to 1 / 4 of the anaerobic reactor. The remaining part is filled with the sewage to be treated. Aeration is carried out continuously for 5 days, and then aeration is stopped. Water is continuously fed in and discharged until the required sludge concentration is reached. Then, high-throughput sequencing is performed on the anaerobic sludge. After the population and abundance requirements are met at the phylum and class levels, normal operation begins. (2) Before the aerobic reactor is put into operation, a mixed ecological sludge of bacteria and algae is used for inoculation. The amount of mixed ecological sludge of bacteria and algae is 1 / 5 to 1 / 4 of the aerobic reactor. The remaining part is filled with the sewage to be treated. The influent and effluent are continuously fed and aerated until the required sludge concentration is reached. Then, the aerobic sludge is subjected to high-throughput sequencing. After the population and abundance requirements are met at the phylum and class level, the reactor can start normal operation. (3) Before the photosynthetic algae reactor is put into operation, water is continuously fed in and out, and light is maintained for 12 hours and darkness for 12 hours. After the required algae SOGR is reached, microalgae sequencing is performed on the photosynthetic algae mud. When the proportion of Chlorophyceae at the class level reaches more than 30%, it is considered that the domestication is successful and normal operation begins. (4) The influent enters the anaerobic reactor through the influent pipe 1. A portion of the effluent returns to the anaerobic reactor through the return pipe 3, the return pump, and the return pipe 1. The sludge in the sedimentation tank returns to the anaerobic reactor through the sludge discharge pump, the sludge discharge pipe 1, and the sludge inlet pipe 1. The influent, return water, and sludge are mixed by the agitator. The organic matter, nitrogen, and phosphorus in the influent are decomposed by the anaerobic sludge in the anaerobic sludge layer. The decomposed gas enters the photosynthetic algae reactor through the gas outlet pipe 1, the aeration pipe 2, and the aeration disc 2. The decomposed pollutants in the water enter the aerobic reactor with the effluent. (5) The effluent from the anaerobic reactor enters the aerobic reactor. Part of the effluent from the photosynthetic algae reactor returns to the aerobic reactor via return pipe three, return pump, and return pipe two. The pollutants in the influent and return effluent are decomposed by the aerobic sludge in the aerobic sludge layer. The decomposed gas enters the photosynthetic algae reactor through gas outlet pipe two, aeration pipe two, and aeration disc two. The decomposed pollutants in the water enter the sedimentation tank with the effluent. (6) The effluent from the aerobic reactor enters the sedimentation tank, where the wastewater undergoes sludge-water separation. The remaining sludge is returned to the anaerobic reactor and the photosynthetic algae reactor through the sludge pump and sludge discharge pipe according to the control requirements. (7) The effluent from the sedimentation tank enters the photosynthetic algae reactor. The wastewater is decomposed by the photosynthetic algae sludge after passing through the photosynthetic algae layer. The generated O2 enters the aerobic reactor through the three air outlet pipes, the one aeration pipe, and the one aeration disc. The effluent is discharged directly, and the algae sludge is discharged periodically as biomass fuel.

6. The wastewater resource recovery method for nitrogen and phosphorus removal without external carbon source according to claim 5, characterized in that, When the effluent meets the standards, the effluent from the photosynthetic algae reactor will not flow back.

7. The wastewater resource recovery method for nitrogen and phosphorus removal without external carbon source as described in claim 5, characterized in that, When the pressure gauge reading exceeds 1.0 MPa, the exhaust valve will automatically open to release the gas.

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