CN210683539U

CN210683539U - System for be used for retrieving carbon, nitrogen, phosphorus and water in sewage

Info

Publication number: CN210683539U
Application number: CN201921745892.2U
Authority: CN
Inventors: 万立国; 熊玲; 张丽君; 陈庆林; 刘红波
Original assignee: Changchun Institute of Applied Chemistry of CAS
Current assignee: Changchun Institute of Applied Chemistry of CAS; Changchun Institute Technology
Priority date: 2019-10-17
Filing date: 2019-10-17
Publication date: 2020-06-05
Anticipated expiration: 2029-10-17

Abstract

The utility model discloses a system for be arranged in retrieving sewage carbon, nitrogen, phosphorus and water, the system is including the catch basin, the grit chamber, first reactor, the second reactor, former feed liquid accumulator, draw liquid accumulator, infiltration membrane subassembly and sedimentation tank, wherein the catch basin is linked together with the sewer network, the catch basin is connected with the grit chamber through the pipeline, the grit chamber still is connected with first reactor through the pipeline, first reactor is connected with former feed liquid accumulator and second reactor through the pipeline respectively, the second reactor still is connected with the sedimentation tank through the pipeline, its method is: step 1, sewage enters a grit chamber through a lifting pump; step 2, producing methane by anaerobic digestion; step 3, continuously concentrating nitrogen and phosphorus resources and then entering a sedimentation tank; step 4, recycling of carbon resources is realized; and 5, refluxing the supernatant into the raw material liquid storage for retreatment. Has the advantages that: the complete recovery of water, carbon, nitrogen and phosphorus resources is realized; has wide application prospect.

Description

System for be used for retrieving carbon, nitrogen, phosphorus and water in sewage

Technical Field

The utility model relates to a system for retrieve carbon, nitrogen, phosphorus and water, in particular to system for retrieving carbon, nitrogen, phosphorus and water in sewage.

Background

At present, water is an important resource produced by a sewage treatment plant and is the most resource, and can be used for various recycling purposes after being properly treated. At present, the biological safety of effluent quality is ensured by adopting a disinfection process under the common condition, and on the basis of common chlorine disinfection, ultraviolet disinfection is practically and widely applied by virtue of the advantages of high efficiency, safety, economy and the like. In recent years, in addition to traditional organic substances, nitrogen and phosphorus pollutants and other pollutants, novel trace organic pollutants, such as Endocrine Disruptors (EDCs), medicines, personal care products (PPCPs) and the like, appear in town sewage, and because of potential risks, removal of the substances should be considered in the process of treating reclaimed water. The membrane technology is favored in water regeneration and reuse due to the characteristics of high efficiency, stability, safety and the like.

The COD in each cubic meter of town sewage is about 0.5kg, the carbon resource lost along with the discharge of the town sewage per year reaches 2000 kilotons, and the estimated energy is about 9.3 times of the energy consumed by sewage treatment; according to the removal of 0.35m per kg of COD³The recovery rate of methane and methane is 80 percent, and the methane can be generated by 60 hundred million meters³The organic matter residue after anaerobic digestion is calculated by 20 percent, and 400 ten thousand t of organic fertilizer can be produced. It can be seen that there is a great potential for recovering carbon resources from wastewater. The most common and most widely used carbon material recovery technique is anaerobic digestion. At present, the excess sludge in the primary sedimentation tank and the secondary sedimentation tank is subjected to anaerobic digestion, organic substances in the sludge are converted into methane, and the methane is further converted into electric energy through a methane generator so as to supplement the power consumption of a sewage treatment plant. But instead of the other end of the tubeThe sludge has non-biological components left in the digestion process, and only about half of the sludge can be converted, so that about only 20% of the organic matters in the sludge are converted into energy for reuse.

Phosphorus belongs to a non-renewable and irreplaceable strategic resource and is exhausted. The inorganic nitrogen in typical town sewage is mainly ammonia nitrogen (free ammonia NH)₃With ionic ammonium salts NH₄ ⁺) In the form of inorganic phosphorus, mainly in the form of Phosphate (PO)₄ ^3-，HPO₄ ^2-，H₂PO₄ ^-) Are present. The recovery method of ammonia nitrogen mainly comprises a chemical precipitation (struvite) method, an adsorption method, an ion exchange method and a membrane separation (reverse osmosis, electrodialysis and the like). The chemical precipitation method needs to add extra phosphorus and magnesium; the adsorption or ion exchange method has less investment and low energy consumption, but needs frequent regeneration; the operation energy consumption of reverse osmosis, electrodialysis and the like is high. The recovery technology of phosphorus resources is various, and mainly comprises a chemical precipitation method, an enhanced biological phosphorus removal method and an adsorption method. The enhanced biological phosphorus removal method requires secondary treatment; the adsorption method has the advantages of simple process, reliable operation and the like, and additional desorption is needed if the phosphorus resource in the adsorbent is recovered.

Disclosure of Invention

The utility model discloses a system for be used for retrieving carbon, nitrogen, phosphorus and water in sewage that the main objective is provided in order to realize resources such as high-efficient recovery cities and towns sewage normal water, carbon, nitrogen and phosphorus.

The utility model provides a system for retrieving sewage well carbon, nitrogen, phosphorus and water is including the catch basin, the grit chamber, first reactor, the second reactor, former feed solution accumulator, draw the liquid accumulator, infiltration membrane subassembly and sedimentation tank, wherein the catch basin is linked together with the sewer network, the catch basin is connected with the grit chamber through the pipeline, the grit chamber still is connected with first reactor through the pipeline, first reactor is connected with former feed solution accumulator and second reactor through the pipeline respectively, the second reactor still is connected with the sedimentation tank through the pipeline, former feed solution accumulator also is connected with the sedimentation tank through the pipeline, former feed solution accumulator is connected through two pipelines with drawing the liquid accumulator, the infiltration membrane subassembly is assembled on two connecting pipelines of former feed solution accumulator and drawing the liquid accumulator.

Be provided with the grid in the catch basin and be used for holding back suspended solid and the floater in the sewage, be equipped with the sewage pump that the elevator pump was used for in the catch basin on the connecting pipeline of catch basin and grit chamber and go into in the grit chamber, be equipped with first peristaltic pump on the connecting pipeline of grit chamber and first reactor, the grit chamber is the aeration grit chamber.

The first reactor is a high-load membrane bioreactor, an ultrafiltration membrane component and aeration stones are arranged in the first reactor, and the effective area of an ultrafiltration membrane in the ultrafiltration membrane component is 0.1m²The size of the membrane is 320 multiplied by 220 multiplied by 5mm³The membrane aperture is 0.1 μm, a second peristaltic pump is arranged on a connecting pipeline between the first reactor and the second reactor, a third peristaltic pump is assembled on the connecting pipeline between the first reactor and the raw material liquid reservoir, a communicating pipe is also arranged on the second reactor and is connected with the connecting pipeline between the first reactor and the raw material liquid reservoir, a fourth peristaltic pump is assembled on the communicating pipe, and a fifth peristaltic pump is assembled on the connecting pipeline between the second reactor and the sedimentation tank.

Be provided with conductivity meter and pH value tester in the former feed liquid accumulator, be equipped with the sixth peristaltic pump on the connecting line of former feed liquid accumulator and sedimentation tank, be equipped with the seventh peristaltic pump on the connecting line of former feed liquid accumulator and infiltration membrane module, be equipped with the eighth peristaltic pump on the connecting line of infiltration membrane module and draw liquid accumulator, the infiltration membrane module comprises the forward osmosis membrane, the effective area of forward osmosis membrane is 30cm²The depth of the flow channel is 2 mm.

The sedimentation tank is internally provided with a stirrer and a pH value tester.

The lifting pump, the first peristaltic pump, the second peristaltic pump, the third peristaltic pump, the fourth peristaltic pump, the fifth peristaltic pump, the conductivity meter, the pH value tester, the sixth peristaltic pump, the seventh peristaltic pump, the eighth peristaltic pump and the stirrer are all assembled by existing equipment, and therefore specific models and specifications are not described in detail.

The utility model provides a method for retrieving carbon, nitrogen, phosphorus and water in sewage, its method is as follows:

step 1, urban sewage enters a water collecting tank through a sewage pipe network, most suspended matters and floating matters are intercepted by the sewage entering the water collecting tank through a grid, and then the sewage enters a grit chamber through a lifting pump;

step 2, pumping the sewage entering the grit chamber into a first reactor for treatment, wherein an ultrafiltration membrane component and aerated stones are arranged in the first reactor, pumping the water separated after being filtered by the ultrafiltration membrane component into a raw material liquid storage, and allowing the concentrated solution treated by the first reactor to be rich in separated organic matters to enter a second reactor through a pipeline for anaerobic digestion to produce methane;

step 3, taking inlet water in the raw material liquid storage as raw material liquid, taking a high-salt solution of a main component KCl in common agricultural fertilizer potash fertilizer as draw liquid in the draw liquid storage, and continuously enabling the raw material liquid in the raw material liquid storage to enter the draw liquid storage through the permeable membrane assembly along with the operation of a forward osmosis system by utilizing high and low osmotic pressure difference, wherein the diluted draw liquid can be directly applied to farmland irrigation to realize irrigation recycling of water resources, and nitrogen and phosphorus resources in the concentrated raw material liquid in the raw material liquid storage are continuously concentrated and enriched and then enter a sedimentation tank;

step 4, enabling the concentrated solution entering the sedimentation tank to generate struvite sediment in the sedimentation tank by adjusting the conditions of pH value and nitrogen-magnesium-phosphorus ratio to be recycled as slow release fertilizer, and pumping the supernatant in the sedimentation tank into a second reactor to perform anaerobic digestion so as to realize complete recovery of carbon resources;

and 5, after methane is generated through anaerobic digestion in the second reactor, residual nitrogen and phosphorus resources can be continuously recovered, and the supernatant in the second reactor is refluxed into the raw material liquid storage for treatment and utilization.

The grit chamber in step 1 is an aeration grit chamber.

The ultrafiltration membrane used in the ultrafiltration membrane component in the step 2 is a flat membrane, and the effective area of the single membrane is 0.1m²The size of the membrane is 320 multiplied by 220 multiplied by 5mm³The aperture of the membrane is 0.1 μm, the material of the membrane is polyvinylidene fluoride, and the material of the support plate is acrylonitrile-butyleneAn alkene-styrene copolymer.

The forward osmosis membrane used in the osmosis membrane component in the step 3 belongs to an asymmetric membrane and consists of an active layer and a supporting layer, wherein the active layer is made of cellulose triacetate, the supporting layer is made of polyester, and the effective area of the forward osmosis membrane is 30cm²The depth of the flow channel is 2 mm.

The struvite in the step 4 is a slow release fertilizer containing Mg: n: the proportion of P is 1:1:1, and the pH value is controlled to be 5-9.5, thus being beneficial to the formation of the compound fertilizer.

The utility model discloses a theory of operation:

municipal sewage enters the water collecting tank through a municipal pipe network. After intercepting most suspended matters and floaters through the grating, the sewage enters the grit chamber through the lifting pump. The effluent quality of the grit chamber is as follows: COD concentration of 270mg/L, TN concentration of 56.9mg/L, NH₄ ⁺Concentration of-N was 47.8mg/L, concentration of TP was 4.9mg/L, PO₄ ^3-The P concentration was 4.14 mg/L.

And then, the effluent of the grit chamber enters a first reactor through a first peristaltic pump, and an ultrafiltration membrane component and aeration stones are arranged in the first reactor. The effective area of the ultrafiltration membrane component is 0.1m²The size of the membrane is 320 multiplied by 220 multiplied by 5mm³The membrane pore size was 0.1. mu.m. After the operation is finished, concentrated solution with the volume of 1/11.5 of that of the raw water and effluent of the ultrafiltration membrane module with the volume of 10.5/11.5 are obtained. The method comprises the following steps of obtaining membrane effluent rich in nitrogen and phosphorus substances while realizing low-carbon recovery of suspended matters and colloidal organic matters in sewage, and enabling concentrated solution in a first reactor to enter a second reactor through a second peristaltic pump for anaerobic digestion to produce methane so as to realize recovery of energy; and the effluent of the ultrafiltration membrane component in the first reactor enters a raw material liquid storage through a third peristaltic pump to recover nitrogen and phosphorus resources in the sewage because the effluent does not contain solid substances and pathogens and is rich in nitrogen and phosphorus elements. The aeration rate in the first reactor is controlled to be 50L/h, the temperature is 25 ℃, the flux is controlled to be 20LMH and other parameter conditions during the operation. The method for cleaning the ultrafiltration membrane in the ultrafiltration membrane component is simple and convenient, the organic matters on the membrane are lightly scraped and returned to the concentrated solution, the surface of the membrane is cleaned by pure water with a certain volume, the cleaning solution is returned to the concentrated solution, and then the surface of the membrane is washed by water so that obvious residue cannot be seenAnd finally soaking the membrane for 2 hours by using a sodium hypochlorite solution (the effective chlorine concentration is 2000mg/L) and then washing the residual chemical agent on the surface of the membrane by using water, wherein the initial state can be recovered to 75%. The recovery rate of the carbon resource can reach about 80 percent. The COD concentration of the effluent of the ultrafiltration section is 42.89mg/L, the TN concentration is 24.3mg/L, and NH₄ ⁺-N concentration of 16.5mg/L, TP concentration of 6.43mg/L, PO₄ ^3-The concentration of-P was 6.4 mg/L.

Effluent in the raw material liquid storage is introduced into the permeable membrane component through a seventh peristaltic pump. In the forward osmosis process of the osmosis membrane module, water entering a raw material liquid reservoir is used as raw material liquid, a high-salt solution of a main component KCl in common agricultural fertilizer potash fertilizer is used as drawing liquid in a drawing liquid reservoir, the raw material liquid and the drawing liquid respectively enter the osmosis membrane module through a seventh peristaltic pump and an eighth peristaltic pump and then respectively return to the raw material liquid reservoir and the drawing liquid reservoir, and the volume of concentrated liquid is 1/10 of the raw material liquid. By utilizing high and low osmotic pressure difference, water in the raw material liquid reservoir continuously enters the draw liquid reservoir through the osmotic membrane component, and the effective area of a forward osmotic membrane in the osmotic membrane component is 30cm²(50 mm. times.60 mm) and the depth of the flow channel is 2 mm. The diluted draw solution in the draw solution storage can be directly used for farmland irrigation to realize the recovery of water resources, and the water reuse rate is more than 85%; and continuously concentrating and enriching nitrogen and phosphorus resources in the concentrated raw material liquid in the raw material liquid storage device so as to facilitate the subsequent recovery of struvite. In the raw material liquid storage, a conductivity meter and a pH value tester are arranged. During the operation, the conditions of parameters such as cross flow speed of 15cm/s, temperature of 25 ℃, concentration of 2mol/L of draw solution and the like are controlled. After the forward osmosis membrane in the osmosis membrane component is operated, the membrane pollution is small, the membrane is easy to clean, and the membrane flux can be recovered by over 75 percent only by carrying out physical cleaning for 15min (the gas-water ratio: 240L/h: 40L/h). The COD concentration of the concentrated solution in the forward osmosis section is 220.88mg/L, the TN concentration is 123.93mg/L, and NH is added₄ ⁺-N concentration 84.15mg/L, TP concentration 57.23mg/L, PO₄ ^3-The P concentration was 56.96 mg/L.

And the concentrated solution in the raw material solution storage enters a sedimentation tank through a sixth peristaltic pump to carry out struvite chemical sedimentation. A pH value tester and a stirrer are arranged in the sedimentation tank. Tong (Chinese character of 'tong')Regulating pH value to 5-9.5, reacting for 20min, N (NH)₄ ⁺)∶n(Mg²⁺)∶n(PO₃ ^4－) Is 4: 1.2: 1, stirring speed is 200rpm, precipitation time is 1h, and after collecting supernatant, the precipitate part is dried at 40 ℃ for 48 h. The nitrogen and phosphorus resources in the sewage are continuously concentrated and exist in a struvite precipitation form, the nitrogen and phosphorus resources can be recycled as slow release fertilizer, the nitrogen and phosphorus resources are recycled, the nitrogen recovery rate reaches more than 80%, the phosphorus recovery rate reaches more than 75%, and the effective phosphorus content in the recycled phosphorus product reaches more than 15%. The COD concentration of the supernatant of the sedimentation tank is 220.88mg/L, the TN concentration is 48.35mg/L, and NH is added₄ ⁺A concentration of-N of 12.44mg/L and a concentration of TP of 10.31mg/L, PO₄ ^3-The P concentration was 10.2 mg/L.

And the supernatant of the sedimentation tank enters a second reactor through a fifth peristaltic pump for anaerobic digestion and methane production. After anaerobic digestion for methane production, collecting gas productivity to realize recovery of carbon resources; the bottom mud can be directly used for solid waste treatment. Because the nitrogen and phosphorus resources in the concentrated solution of the ultrafiltration section and the supernatant of the struvite recovery section are not completely recovered, the supernatant after anaerobic digestion and methane production in the second reactor flows back to the raw material solution storage through the fourth peristaltic pump to continue concentration and enrichment.

The utility model has the advantages that:

the technical scheme provided by the utility model compare in prior art, realized under the condition that the procedure is simple, low energy consumption, carbon emission are few, still have required sewage treatment effect. The complete recovery of water, carbon, nitrogen and phosphorus resources is realized: the water resource is efficiently recovered, and the water reuse rate is more than 85 percent; the carbon resource is efficiently recovered, and the methane recovery rate can reach 80 percent; the nitrogen and phosphorus resources are efficiently recovered, the nitrogen recovery rate reaches more than 80%, the phosphorus recovery rate reaches more than 75%, and the effective phosphorus content in the recovered phosphorus product reaches more than 15%; the forward osmosis membrane has little pollution and is easy to clean, and the membrane flux can be restored to more than 75 percent after physical cleaning for 15 min; has wide application prospect.

Drawings

Fig. 1 is the overall structure schematic diagram of the recovery system of the present invention.

The labels in the above figures are as follows:

1. the device comprises a water collecting tank 2, a grit chamber 3, a first reactor 4, a second reactor 5, a raw material liquid storage 6, a drawing liquid storage 7, a permeable membrane module 8, a sedimentation tank 9, a grid 10, a lift pump 11, a first peristaltic pump 12, an ultrafiltration membrane module 13, an aeration stone 14, a second peristaltic pump 15, a third peristaltic pump 16, a communicating pipe 17, a fourth peristaltic pump 18, a fifth peristaltic pump 19, a conductivity meter 20, a pH value tester 21, a sixth peristaltic pump 22, a seventh peristaltic pump 23, an eighth peristaltic pump 24 and a stirrer.

Detailed Description

Please refer to fig. 1:

the system for recovering carbon, nitrogen, phosphorus and water in sewage provided by the utility model comprises a water collecting tank 1, a grit chamber 2, a first reactor 3, a second reactor 4, a raw material liquid storage 5, a drawing liquid storage 6, a permeable membrane component 7 and a sedimentation tank 8, wherein the water catch bowl 1 is linked together with the sewage pipe network, the water catch bowl 1 is connected with grit chamber 2 through the pipeline, grit chamber 2 still is connected with first reactor 3 through the pipeline, first reactor 3 is connected with former feed liquid accumulator 5 and second reactor 4 through the pipeline respectively, second reactor 4 still is connected with sedimentation tank 8 through the pipeline, former feed liquid accumulator 5 also is connected with sedimentation tank 8 through the pipeline, former feed liquid accumulator 5 is connected through two pipelines with drawing liquid accumulator 6, osmotic membrane subassembly 7 assembles on former feed liquid accumulator 5 and two connecting pipelines of drawing liquid accumulator 6.

Be provided with grid 9 in the catch basin 1 and be used for separating out the debris in the sewage, be equipped with in the sewage pump income grit chamber 2 that elevator pump 10 is used for in the catch basin 1 is gone into with grit chamber 2 to the connecting pipeline of catch basin 1 and grit chamber 2, be equipped with first peristaltic pump 11 on the connecting pipeline of grit chamber 2 and first reactor 3, grit chamber 2 is the aeration grit chamber.

The first reactor 3 is a high-load membrane bioreactor, an ultrafiltration membrane component 12 and an aeration stone 13 are arranged in the first reactor 3, and the effective area of an ultrafiltration membrane in the ultrafiltration membrane component 12 is 0.1m²The size of the membrane is 320 multiplied by 220 multiplied by 5mm³The membrane pore diameter is 0.1 μm, the first reactor 3 and the second reactorA second peristaltic pump 14 is arranged on a connecting pipeline between the reactors 4, a third peristaltic pump 15 is assembled on the connecting pipeline between the first reactor 3 and the raw material liquid storage 5, a communicating pipe 16 is also arranged on the second reactor 4 and is connected with the connecting pipeline between the first reactor 3 and the raw material liquid storage 5, a fourth peristaltic pump 17 is assembled on the communicating pipe 16, and a fifth peristaltic pump 18 is assembled on the connecting pipeline between the second reactor 4 and the sedimentation tank 8.

Be provided with conductivity meter 19 and pH value tester 20 in the former feed liquid accumulator 5, be equipped with sixth peristaltic pump 21 on the connecting line of former feed liquid accumulator 5 and sedimentation tank 8, be equipped with seventh peristaltic pump 22 on the connecting line of former feed liquid accumulator 5 and osmotic membrane subassembly 7, be equipped with eighth peristaltic pump 23 on the connecting line of osmotic membrane subassembly 7 and draw liquid accumulator 6, osmotic membrane subassembly 7 comprises the forward osmosis membrane, the effective area of forward osmosis membrane is 30cm²The depth of the flow channel is 2 mm.

The sedimentation tank 8 is equipped with a stirrer 24 and a pH tester 20.

The lift pump 10, the first peristaltic pump 11, the second peristaltic pump 14, the third peristaltic pump 15, the fourth peristaltic pump 17, the fifth peristaltic pump 18, the conductivity meter 19, the pH tester 20, the sixth peristaltic pump 21, the seventh peristaltic pump 22, the eighth peristaltic pump 23, and the agitator 24 are all assembled in the existing equipment, and therefore specific models and specifications are not described in detail.

step 1, urban sewage enters a water collecting tank 1 through a sewage pipe network, most suspended matters and floating matters are intercepted by the sewage entering the water collecting tank 1 through a grating 9, and then the sewage enters a grit chamber 2 through a lifting pump 10;

step 2, pumping the sewage entering the grit chamber 2 into a first reactor 3 for treatment, arranging an ultrafiltration membrane assembly 7 and an aeration stone 13 in the first reactor 3, pumping the water separated after being filtered by the ultrafiltration membrane assembly 7 into a raw material liquid storage 5, and allowing the concentrated solution treated by the first reactor 3 to be rich in separated organic matters to enter a second reactor 4 through a pipeline for anaerobic digestion to produce methane;

step 3, taking the inlet water in the raw material liquid storage 5 as raw material liquid, taking a high-salt solution of a main component KCl in common agricultural fertilizer potash fertilizer as a drawing liquid in the drawing liquid storage 6, and continuously feeding the raw material liquid in the raw material liquid storage 5 into the drawing liquid storage 6 through the osmotic membrane assembly 7 by utilizing high and low osmotic pressure difference along with the operation of a forward osmosis system, wherein the diluted drawing liquid can be directly applied to farmland irrigation to realize irrigation recycling of water resources, and the nitrogen and phosphorus resources in the concentrated raw material liquid in the raw material liquid storage 5 continuously concentrate and enrich and then enter the sedimentation tank 8;

step 4, enabling the concentrated solution entering the sedimentation tank 8 to generate struvite sediment in the sedimentation tank 8 through adjusting the conditions of pH value and nitrogen-magnesium-phosphorus ratio, recycling the struvite sediment as slow release fertilizer, and pumping the supernatant in the sedimentation tank 8 into the second reactor 4 to perform anaerobic digestion so as to realize complete recovery of carbon resources;

and 5, after methane is generated through anaerobic digestion in the second reactor 4, residual nitrogen and phosphorus resources can be continuously recycled, and the supernatant in the second reactor 4 flows back to the raw material liquid storage 5 for treatment and utilization.

The grit chamber 2 in the step 1 is an aeration grit chamber.

The ultrafiltration membrane used in the ultrafiltration membrane component 12 in the step 2 is a flat membrane, and the effective area of the single membrane is 0.1m²The size of the membrane is 320 multiplied by 220 multiplied by 5mm³The aperture of the membrane is 0.1 μm, the material of the membrane is polyvinylidene fluoride, and the material of the support plate is acrylonitrile-butadiene-styrene copolymer.

The forward osmosis membrane used in the osmosis membrane component 7 in the step 3 belongs to an asymmetric membrane and consists of an active layer and a supporting layer, wherein the active layer is made of cellulose triacetate, the supporting layer is made of polyester, and the effective area of the forward osmosis membrane is 30cm²The depth of the flow channel is 2 mm.

The utility model discloses a theory of operation:

municipal sewage passes through municipal pipe networkAnd enters a water collecting tank 1. After most suspended matters and floating objects are intercepted by the grating 9, the sewage enters the grit chamber 2 through the lifting pump 10. The effluent quality of the grit chamber 2 is as follows: COD concentration of 270mg/L, TN concentration of 56.9mg/L, NH₄ ⁺Concentration of-N was 47.8mg/L, concentration of TP was 4.9mg/L, PO₄ ^3-The P concentration was 4.14 mg/L.

Then, the effluent of the grit chamber 2 enters a first reactor 3 through a first peristaltic pump 11, and an ultrafiltration membrane component 12 and an aeration stone 13 are arranged in the first reactor 3. The effective area of the ultrafiltration membrane in the ultrafiltration membrane module 12 is 0.1m²The size of the membrane is 320 multiplied by 220 multiplied by 5mm³The membrane pore size was 0.1. mu.m. After the operation is finished, concentrated solution with the volume of 1/11.5 of that of the raw water and effluent of the ultrafiltration membrane module 12 with the volume of 10.5/11.5 are obtained. The low-carbon recovery of suspended matters and colloidal organic matters in the sewage is realized, meanwhile, membrane effluent rich in nitrogen and phosphorus substances is obtained, concentrated solution in the first reactor 3 enters the second reactor 4 through the second peristaltic pump 14 for anaerobic digestion to produce methane, and the recovery of energy is realized; the effluent of the ultrafiltration membrane component 12 in the first reactor 3, which contains no solid matter and pathogen and is rich in nitrogen and phosphorus elements, enters the raw material liquid storage 5 through the third peristaltic pump 15 to recover nitrogen and phosphorus resources in the sewage. The aeration rate in the first reactor 3 is controlled to be 50L/h, the temperature is 25 ℃, the flux is controlled to be 20LMH and other parameter conditions during the operation. The method for cleaning the ultrafiltration membrane in the ultrafiltration membrane component 12 is simple and convenient, the organic matters on the membrane sheet are lightly scraped and returned to the concentrated solution, the surface of the membrane is cleaned by pure water with a certain volume, the cleaning solution is returned to the concentrated solution, then the surface of the membrane is washed by water until no obvious residual pollutants can be seen, finally sodium hypochlorite solution (with the effective chlorine concentration of 2000mg/L) is used for soaking for 2 hours, and then the residual chemical agents on the surface of the membrane are washed by water, so that 75% of the initial state can be recovered. The recovery rate of the carbon resource can reach about 80 percent. The COD concentration of the effluent of the ultrafiltration section is 42.89mg/L, the TN concentration is 24.3mg/L, and NH₄ ⁺-N concentration of 16.5mg/L, TP concentration of 6.43mg/L, PO₄ ^3-The concentration of-P was 6.4 mg/L.

Effluent from the feed reservoir 5 is introduced into the osmotic membrane module 7 by a seventh peristaltic pump 22. During forward osmosis of the osmosis membrane module 7, with a feed liquid reservoir5, taking inlet water as raw material liquid, taking a high-salt solution of a main component KCl in common agricultural fertilizer potash fertilizer as drawing liquid in a drawing liquid storage 6, enabling the raw material liquid and the drawing liquid to respectively enter an osmotic membrane assembly 7 through a seventh peristaltic pump 22 and an eighth peristaltic pump 23, then respectively returning to the raw material liquid storage 5 and the drawing liquid storage 6, and enabling the volume of concentrated liquid to be 1/10 of the raw material liquid. By utilizing high and low osmotic pressure difference, water in the raw material liquid storage 5 continuously enters the drawing liquid storage 6 through the osmotic membrane assembly 7, and the effective area of a forward osmotic membrane in the osmotic membrane assembly 7 is 30cm²(50 mm. times.60 mm) and the depth of the flow channel is 2 mm. The diluted draw solution in the draw solution storage 6 can be directly used for farmland irrigation to realize the recovery of water resources, and the water reuse rate is more than 85%; the nitrogen and phosphorus resources in the concentrated raw material liquid in the raw material liquid storage 5 are continuously concentrated and enriched so as to facilitate the subsequent recovery of struvite. A conductivity meter 19 and a pH meter 20 are provided in the raw material liquid reservoir 5. During the operation, the conditions of parameters such as cross flow speed of 15cm/s, temperature of 25 ℃, concentration of 2mol/L of draw solution and the like are controlled. After the forward osmosis membrane in the osmosis membrane component 7 is operated, the membrane pollution is small, the membrane is easy to clean, and the membrane flux can be recovered by over 75 percent only by carrying out physical cleaning for 15min (gas-water ratio: 240L/h: 40L/h). The COD concentration of the concentrated solution in the forward osmosis section is 220.88mg/L, the TN concentration is 123.93mg/L, and NH is added₄ ⁺-N concentration 84.15mg/L, TP concentration 57.23mg/L, PO₄ ^3-The P concentration was 56.96 mg/L.

The concentrated solution in the raw material liquid storage 5 enters the sedimentation tank 8 through a sixth peristaltic pump 21 to carry out struvite chemical sedimentation. The sedimentation tank 8 is provided with a pH value tester 20 and a stirrer 24. The pH value is adjusted to be 9.2, the reaction time is 20min, and N (NH)₄ ⁺)∶n(Mg²⁺)∶n(PO₃ ^4－) Is 4: 1.2: 1, stirring speed is 200rpm, precipitation time is 1h, and after collecting supernatant, the precipitate part is dried at 40 ℃ for 48 h. The nitrogen and phosphorus resources in the sewage are continuously concentrated and exist in a struvite precipitation form, the nitrogen and phosphorus resources can be recycled as slow release fertilizer, the nitrogen and phosphorus resources are recycled, the nitrogen recovery rate reaches more than 80%, the phosphorus recovery rate reaches more than 75%, and the effective phosphorus content in the recycled phosphorus product reaches more than 15%. Supernatant C of sedimentation tank 8OD concentration of 220.88mg/L, TN concentration of 48.35mg/L, NH₄ ⁺A concentration of-N of 12.44mg/L and a concentration of TP of 10.31mg/L, PO₄ ^3-The P concentration was 10.2 mg/L.

The supernatant of the sedimentation tank 8 enters the second reactor 4 through a fifth peristaltic pump 18 for anaerobic digestion and methane production. After anaerobic digestion for methane production, collecting gas productivity to realize recovery of carbon resources; the bottom mud can be directly used for solid waste treatment. Because the nitrogen and phosphorus resources in the concentrated solution of the ultrafiltration section and the supernatant of the struvite recovery section are not completely recovered, the supernatant after anaerobic digestion and methane production in the second reactor 4 flows back to the raw material solution reservoir 5 through the fourth peristaltic pump 17 to continue concentration and enrichment.

Claims

1. A system for recovering carbon, nitrogen, phosphorus and water in sewage, characterized in that: the device comprises a water collecting tank, a grit chamber, a first reactor, a second reactor, a raw material liquid storage, a drawing liquid storage, a permeable membrane component and a sedimentation tank, wherein the water collecting tank is communicated with a sewage pipe network, the water collecting tank is connected with the grit chamber through a pipeline, the grit chamber is also connected with the first reactor through a pipeline, the first reactor is respectively connected with the raw material liquid storage and the second reactor through pipelines, the second reactor is also connected with the sedimentation tank through a pipeline, the raw material liquid storage and the drawing liquid storage are connected through two pipelines, and the permeable membrane component is assembled on the two connecting pipelines of the raw material liquid storage and the drawing liquid storage.

2. The system for recovering carbon, nitrogen, phosphorus and water in sewage according to claim 1, wherein: the catch basin in be provided with the grid and be used for holding back suspended solid and floater in the sewage, be equipped with the sewage pump that the elevator pump is used for in the catch basin on the connecting line of catch basin and grit chamber and go into in the grit chamber, be equipped with first peristaltic pump on the connecting line of grit chamber and first reactor, the grit chamber is aeration grit chamber.

3. The method of claim 1A system for retrieving carbon, nitrogen, phosphorus and water in sewage, its characterized in that: the first reactor is a high-load membrane bioreactor, an ultrafiltration membrane component and an aeration stone are arranged in the first reactor, and the effective area of an ultrafiltration membrane in the ultrafiltration membrane component is 0.1m²The size of the membrane is 320 multiplied by 220 multiplied by 5mm³The membrane aperture is 0.1 μm, a second peristaltic pump is arranged on a connecting pipeline between the first reactor and the second reactor, a third peristaltic pump is assembled on the connecting pipeline between the first reactor and the raw material liquid reservoir, a communicating pipe is also arranged on the second reactor and is connected with the connecting pipeline between the first reactor and the raw material liquid reservoir, a fourth peristaltic pump is assembled on the communicating pipe, and a fifth peristaltic pump is assembled on the connecting pipeline between the second reactor and the sedimentation tank.

4. The system for recovering carbon, nitrogen, phosphorus and water in sewage according to claim 1, wherein: the feed solution reservoir in be provided with conductivity meter and pH value tester, be equipped with the sixth peristaltic pump on the connecting line of feed solution reservoir and sedimentation tank, be equipped with the seventh peristaltic pump on the connecting line of feed solution reservoir and osmotic membrane subassembly, be equipped with the eighth peristaltic pump on the connecting line of osmotic membrane subassembly and draw liquid reservoir, the osmotic membrane subassembly comprises the forward osmosis membrane, the effective area of forward osmosis membrane is 30cm²The depth of the flow channel is 2 mm.

5. The system for recovering carbon, nitrogen, phosphorus and water in sewage according to claim 1, wherein: and a stirrer and a pH value tester are assembled in the sedimentation tank.