CN210683539U - A system for recycling carbon, nitrogen, phosphorus and water from sewage - Google Patents

Abstract

The utility model discloses a system for recovering carbon, nitrogen, phosphorus and water in sewage. The system comprises a water collecting tank, a grit chamber, a first reactor, a second reactor, a raw material liquid storage tank, and a drawing liquid storage tank. The water collecting tank is connected with the sewage pipe network, the water collecting tank is connected with the grit chamber through the pipeline, and the grit chamber is also connected with the first reactor through the pipeline, and the first reactor They are respectively connected with the raw material liquid storage and the second reactor through pipelines, and the second reactor is also connected with the sedimentation tank through pipelines. Anaerobic digestion produces methane; step 3, nitrogen and phosphorus resources are continuously concentrated and then enter the sedimentation tank; step 4, realize the recovery of carbon resources; step 5, return the supernatant to the raw material liquid storage for reprocessing. Beneficial effects: the complete recovery of water, carbon, nitrogen and phosphorus resources is realized; the invention has broad application prospects.

Description

A system for recycling carbon, nitrogen, phosphorus and water from sewage

technical field

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

Background technique

Currently, water is an important resource and the most abundant resource produced by sewage treatment plants, and can be used for various reuse purposes after proper treatment. At present, disinfection process is usually used to ensure the biological safety of effluent water quality. On the basis of commonly used chlorine disinfection, ultraviolet disinfection has been widely used in practice due to its advantages of high efficiency, safety and economy. In recent years, in addition to traditional organic matter, nitrogen and phosphorus and other pollutants, new trace organic pollutants, such as endocrine disruptors (EDCs), pharmaceuticals and personal care products (PPCPs), have also appeared in urban sewage. Risks, the removal of these substances should also be considered in the reclaimed water treatment process. Membrane technology is favored in water regeneration and reuse due to its high efficiency, stability, safety and other characteristics.

Every cubic meter of urban sewage contains about 0.5kg ^of COD, and the carbon resources lost with urban sewage discharge each year amount to 20 million tons, which is estimated to be about 9.3 times the energy consumption of sewage treatment; If the methane recovery rate is 80%, 6 billion m ³ of methane can be produced, and the residual organic matter after anaerobic digestion can be calculated as 20%, which can produce 4 million tons of organic fertilizer. It can be seen that the recovery of carbon resources from sewage has a very large potential. The most common and widely used carbon recovery technology is anaerobic digestion technology. At present, the excess sludge in the primary and secondary sedimentation tanks is anaerobic digested, and the organic matter in the sludge is converted into methane, which is further converted into electricity through the biogas generator to supplement the electricity consumption of the sewage treatment plant. However, the sludge has residual non-biomass components during the digestion process, and only about half of the sludge can be converted. Therefore, only about 20% of the organic matter in the sludge is converted into energy for reuse.

Phosphorus is a non-renewable and irreplaceable strategic resource, which is depleted. The inorganic nitrogen in typical urban sewage is mainly in the form of ammonia nitrogen (free ammonia NH ₃ and ionic ammonium salt NH ₄ ⁺ ), and the inorganic phosphorus is mainly in the form of phosphate (PO ₄ ^3- , HPO ₄ ^2- , H ₂ PO ₄ ^{- )} )exist. The recovery methods of ammonia nitrogen mainly include chemical precipitation (struvite) method, adsorption method, ion exchange method and membrane separation (reverse osmosis, electrodialysis, etc.) method. The chemical precipitation method requires additional addition of phosphorus and magnesium; the adsorption or ion exchange method requires less investment and low energy consumption, but requires frequent regeneration; reverse osmosis, electrodialysis and other operating energy consumption are high. There are various recovery technologies for phosphorus resources, mainly chemical precipitation, enhanced biological phosphorus removal, and adsorption. Strengthening the biological phosphorus removal method requires secondary treatment; the adsorption method has the advantages of simple process and reliable operation, and additional desorption is required to recover the phosphorus resources in the adsorbent.

SUMMARY OF THE INVENTION

The main purpose of the utility model is to provide a system for recovering carbon, nitrogen, phosphorus and water in sewage, which is provided for efficiently recovering resources such as water, carbon, nitrogen and phosphorus in urban sewage.

The system for recovering carbon, nitrogen, phosphorus and water in sewage provided by the utility model includes a sump, a grit chamber, a first reactor, a second reactor, a raw material liquid storage, a drawing liquid storage, a permeable membrane The assembly and the sedimentation tank, wherein the water collection tank is communicated with the sewage pipe network, the water collection tank is connected with the grit chamber through the pipeline, and the grit chamber is also connected with the first reactor through the pipeline, and the first reactors are respectively connected through the pipeline It is connected with the raw material liquid storage and the second reactor, the second reactor is also connected with the sedimentation tank through the pipeline, the raw material liquid storage is also connected with the sedimentation tank through the pipeline, the raw liquid storage and the drawing liquid storage Connected by two pipelines, the permeable membrane assembly is assembled on the two connecting pipelines of the raw material liquid storage and the drawing liquid storage.

There is a grille in the collection tank to intercept the suspended solids and floating objects in the sewage. The connection pipeline between the collection tank and the grit chamber is equipped with a lift pump for pumping the sewage in the collection tank into the grit chamber. A first peristaltic pump is assembled on the connecting pipeline of the first reactor, and the grit chamber is an aeration grit chamber.

The first reactor is a high-load membrane bioreactor. The first reactor is provided with an ultrafiltration membrane module and aeration stone. The effective area of the ultrafiltration membrane in the ultrafiltration membrane module is 0.1m ² , and the size of the membrane is length × width. × height = 320 × 220 × 5 mm ³ , the pore size of the membrane is 0.1 μm, a second peristaltic pump is provided on the connecting pipeline between the first reactor and the second reactor, and the connection between the first reactor and the raw material liquid storage The connection pipeline is equipped with a third peristaltic pump, and the second reactor is also provided with a communication pipe to be connected with the connection pipeline between the first reactor and the raw material liquid storage, and the communication pipe is equipped with a fourth peristaltic pump , the connection pipeline between the second reactor and the sedimentation tank is equipped with a fifth peristaltic pump.

A conductivity meter and a pH value tester are installed in the raw material liquid storage tank, a sixth peristaltic pump is installed on the connecting pipeline between the raw material liquid storage tank and the sedimentation tank, and a seventh peristaltic pump is installed on the connecting pipeline between the raw material liquid storage tank and the osmotic membrane assembly. The peristaltic pump, an eighth peristaltic pump is installed on the connecting pipeline between the permeable membrane module and the liquid storage reservoir, and the permeable membrane module is composed of a forward osmosis membrane, the effective area of the forward osmosis membrane is 30cm ² , and the depth of the flow channel is 2mm.

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

Above-mentioned 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 Eight peristaltic pumps and agitators are all assemblies of existing equipment, so the specific models and specifications are not described in detail.

The method for recycling carbon, nitrogen, phosphorus and water in sewage provided by the present invention is as follows:

Step 1. The urban sewage enters the collection tank through the sewage pipe network, and the sewage entering the collection tank passes through the grille to intercept most of the suspended matter and floating matter, and then enters the grit chamber through the lift pump;

Step 2. The sewage entering the grit chamber is pumped into the first reactor for treatment. The first reactor is provided with an ultrafiltration membrane module and aeration stone, and the water separated after being filtered by the ultrafiltration membrane module is pumped into the raw material. Liquid storage tank, the concentrated liquid processed by the first reactor is rich in separated organics and enters the second reactor through pipelines for anaerobic digestion to produce methane;

Step 3, the influent water in the raw material liquid storage tank is used as the raw material liquid, and the high-salt solution of the main component KCl in the common agricultural fertilizer potash fertilizer is used as the drawing liquid in the drawing liquid storage tank. With the operation of the forward osmosis system, the high and low osmotic pressure Poor, so that the raw material liquid in the raw material liquid storage tank continuously enters into the drawing liquid storage tank through the osmotic membrane module, and the diluted drawing liquid can be directly used for farmland irrigation, realizing the irrigation and reuse of water resources, and the concentrated liquid in the raw material liquid storage tank. The nitrogen and phosphorus resources in the raw material liquid are continuously concentrated and enriched and then enter the sedimentation tank;

Step 4. By adjusting the pH value and the ratio of nitrogen, magnesium and phosphorus, the concentrated solution entering the sedimentation tank generates struvite precipitation in the sedimentation tank, which is recycled as slow-release fertilizer, and the supernatant in the sedimentation tank is pumped back to Anaerobic digestion is carried out in the second reactor to achieve complete recovery of carbon resources;

Step 5. After anaerobic digestion in the second reactor to generate methane, the residual nitrogen and phosphorus resources can be continuously recovered, and the supernatant in the second reactor is returned to the raw material liquid storage for reuse.

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

The ultrafiltration membrane used in the ultrafiltration membrane module in step 2 is a flat membrane, the effective area of a single membrane is 0.1m ² , the size of the membrane sheet is length×width×height=320×220×5mm ³ , the pore size of the membrane is 0.1 μm, and the membrane size is 0.1 μm. The material is polyvinylidene fluoride, and the material of the support plate is acrylonitrile-butadiene-styrene copolymer.

The forward osmosis membrane used in the permeable membrane module in step 3 belongs to an asymmetric membrane, which consists of an active layer and a support layer, wherein the material of the active layer is triacetate fiber, the material of the support layer is polyester, and the effective area of the forward osmosis membrane is 30cm ² , The runner depth is 2mm.

The struvite in step 4 is a slow-release fertilizer, the ratio of Mg:N:P is 1:1:1, and the pH value is controlled at 5-9.5, which is beneficial to the formation of this compound fertilizer.

The working principle of the present utility model:

Urban sewage enters the sump through the municipal pipe network. After the sewage passes through the grille to intercept most of the suspended matter and floating matter, it enters the grit chamber through the lift pump. Grit chamber effluent quality: COD concentration is 270mg/L, TN concentration is 56.9mg/L, NH ₄ ⁺ -N concentration is 47.8mg/L, TP concentration is 4.9mg/L, PO ₄ ^3- -P concentration is 4.14 mg/L.

Then, the effluent from the grit chamber enters the first reactor through the first peristaltic pump, and the first reactor is provided with an ultrafiltration membrane module and an aeration stone. The effective area of the ultrafiltration membrane module is 0.1 m ² , the size of the membrane sheet is length×width×height=320×220×5 mm ³ , and the membrane pore size is 0.1 μm. After the operation, the concentrated solution of 1/11.5 of the original water volume was obtained, and the effluent of the ultrafiltration membrane module of 10.5/11.5 was obtained. While realizing the low-carbon recovery of suspended solids and colloidal organic matter in the sewage, the membrane effluent rich in nitrogen and phosphorus is obtained, and the concentrate in the first reactor enters the second reactor through the second peristaltic pump for anaerobic digestion to produce methane , to achieve energy recovery; the effluent of the ultrafiltration membrane module in the first reactor, because it does not contain solid substances and pathogens and is rich in nitrogen and phosphorus elements, enters the raw material liquid storage through the third peristaltic pump to recover nitrogen and phosphorus resources in sewage. During the operation, parameters such as the aeration rate of 50L/h, the temperature of 25°C, and the flux of 20LMH in the first reactor were controlled. The cleaning method of the ultrafiltration membrane in the ultrafiltration membrane module is simple and convenient. The organic matter on the membrane is gently scraped off, returned to the concentrated solution, and the membrane surface is washed with a certain volume of pure water, and the cleaning solution is returned to the concentrated solution, and then Rinse the membrane surface with water until no obvious residual pollutants can be seen. Finally, soak it with sodium hypochlorite solution (available chlorine concentration 2000mg/L) for 2 hours, and then rinse the residual chemical agent on the membrane surface with water to restore 75% of the original state. The recovery rate of carbon resources can reach about 80%. The concentration of COD in the effluent of the ultrafiltration section is 42.89mg/L, the concentration of TN is 24.3mg/L, the concentration of NH ₄ ⁺ -N is 16.5mg/L, the concentration of TP is 6.43mg/L, and the concentration of PO ₄ ^3- -P is 6.4mg /L.

The effluent in the raw material liquid storage is introduced into the permeable membrane module through the seventh peristaltic pump. In the forward osmosis process of the osmotic membrane module, the feed water of the raw material liquid storage tank is used as the raw material liquid, and the high-salt solution of KCl, the main component of the common agricultural fertilizer potash fertilizer, is used as the drawing liquid in the drawing liquid storage tank. The raw material liquid and the drawing liquid are respectively Enter the osmotic membrane module through the seventh peristaltic pump and the eighth peristaltic pump, and then return to the raw material liquid storage and the drawing liquid storage respectively, and the volume of the concentrated liquid is 1/10 of the raw material liquid. Utilizing the high and low osmotic pressure difference, the water in the raw material liquid reservoir continuously enters the drawing liquid reservoir through the osmotic membrane module. The effective area of the forward osmosis membrane in the osmotic membrane module is 30cm ² (50mm×60mm), and the depth of the flow channel is 2mm. . The diluted drawing liquid in the drawing liquid storage can be directly used for farmland irrigation to realize the recovery of water resources, and the water reuse rate is over 85%; the nitrogen and phosphorus resources in the concentrated raw material liquid in the raw material liquid storage are continuously concentrated. enriched for subsequent struvite recovery. In the raw material liquid storage, a conductivity meter and a pH value tester are provided. During the operation, parameters such as cross-flow velocity of 15 cm/s, temperature of 25 °C, and concentration of drawn liquid of 2 mol/L were controlled. After the operation of the forward osmosis membrane in the permeable membrane module is completed, the membrane pollution is small and easy to clean. It only takes 15 minutes of physical cleaning (gas-water ratio: 240L/h: 40L/h) to restore the membrane flux by more than 75%. The COD concentration of the concentrate in the forward osmosis section is 220.88mg/L, the TN concentration is 123.93mg/L, the NH ₄ ⁺ -N concentration is 84.15mg/L, the TP concentration is 57.23mg/L, and the PO ₄ ^3- -P concentration is 56.96 mg/L.

The concentrated liquid in the raw material liquid storage tank enters the sedimentation tank through the sixth peristaltic pump for chemical precipitation of struvite. A pH tester and agitator are provided in the sedimentation tank. By adjusting the pH value, it is controlled at 5-9.5, the reaction time is 20min, the n(NH ₄ ⁺ ):n(Mg ²⁺ ):n(PO ₃ ^4- ) is 4:1.2:1, the stirring speed is 200rpm, and the precipitation time is After collecting the supernatant, the precipitated part was dried at 40°C for 48h. The nitrogen and phosphorus resources in the sewage are continuously concentrated and exist in the form of struvite precipitation, which can be recycled as slow-release fertilizers to realize the recovery of nitrogen and phosphorus resources. The nitrogen recovery rate is over 80% and the phosphorus recovery rate is over 75%. The content of available phosphorus in the recovered phosphorus product is over 15%. The concentration of COD in the supernatant of the sedimentation tank is 220.88mg/L, the concentration of TN is 48.35mg/L, the concentration of NH ₄ ⁺ -N is 12.44mg/L, the concentration of TP is 10.31mg/L, and the concentration of PO ₄ ^3- -P is 10.2mg /L.

The supernatant of the sedimentation tank enters the second reactor for anaerobic digestion and methane production through the fifth peristaltic pump. After anaerobic digestion to produce methane, the gas production capacity is collected to realize the recovery of carbon resources; the sediment can be directly treated as solid waste. Since the nitrogen and phosphorus resources in the concentrated liquid of the ultrafiltration section and the supernatant liquid of the struvite recovery section were not completely recovered, the supernatant liquid after anaerobic digestion and methane production in the second reactor was returned to the raw material liquid storage tank through the fourth peristaltic pump , continue to concentrate and enrich.

The beneficial effects of the present utility model:

Compared with the prior art, the technical solution provided by the utility model achieves the required sewage treatment effect under the conditions of simple process, low energy consumption and low carbon emission. Realize the complete recovery of water, carbon, nitrogen and phosphorus resources: efficient recovery of water resources, the water reuse rate is over 85%; efficient recovery of carbon resources, the recovery rate of methane can reach 80%; efficient recovery of nitrogen, phosphorus resources, nitrogen The recovery rate is over 80%, the phosphorus recovery rate is over 75%, and the effective phosphorus content in the recovered phosphorus product is over 15%; the forward osmosis membrane membrane has little pollution and is easy to clean, and the membrane flux can recover 75% after 15 minutes of physical cleaning above; has broad application prospects.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of the recycling system according to the present invention.

The annotations in the figure above are as follows:

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

Detailed ways

See Figure 1:

The system for recovering carbon, nitrogen, phosphorus and water in sewage provided by the present invention includes 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 The reservoir 6, the permeable membrane assembly 7 and the sedimentation tank 8, wherein the water collection tank 1 is connected with the sewage pipe network, the water collection tank 1 is connected with the sand settling tank 2 through the pipeline, and the sand settling tank 2 is also connected with the first reaction tank through the pipeline. The first reactor 3 is connected to the raw material liquid storage tank 5 and the second reactor 4 respectively through pipelines, the second reactor 4 is also connected to the sedimentation tank 8 through pipelines, and the raw material liquid storage tank 5 It is also connected to the sedimentation tank 8 through pipelines, the raw material liquid storage 5 and the drawn liquid storage 6 are connected through two pipelines, and the permeable membrane assembly 7 is assembled on two of the raw material liquid storage 5 and the drawn liquid storage 6 . on the connecting line.

The sump 1 is provided with a grille 9 for separating out the sundries in the sewage, and the connecting pipeline between the sump 1 and the grit chamber 2 is equipped with a lift pump 10 for pumping the sewage in the sump 1 into the grit chamber 2 Inside, the connection pipeline between the grit chamber 2 and the first reactor 3 is equipped with a first peristaltic pump 11, and the grit chamber 2 is an aerated grit chamber.

The first reactor 3 is a high-load membrane bioreactor. The first reactor 3 is provided with an ultrafiltration membrane assembly 12 and an aeration stone 13. The effective area of the ultrafiltration membrane in the ultrafiltration membrane assembly 12 is 0.1 m ² . Sheet size L×W×H=320×220×5mm ³ , the membrane aperture is 0.1 μm, the connecting pipeline between the first reactor 3 and the second reactor 4 is provided with a second peristaltic pump 14, the first reactor 3 and the connection pipeline between the raw material liquid storage 5 is equipped with the third peristaltic pump 15, the second reactor 4 is also provided with a connecting pipe 16 and the connection between the first reactor 3 and the raw material liquid storage 5 The pipelines are connected, a fourth peristaltic pump 17 is mounted on the communication pipe 16 , and a fifth peristaltic pump 18 is mounted on the connecting pipeline between the second reactor 4 and the sedimentation tank 8 .

The raw material liquid storage 5 is provided with a conductivity meter 19 and a pH value tester 20, the connection pipeline between the raw material liquid storage 5 and the sedimentation tank 8 is equipped with a sixth peristaltic pump 21, the raw material liquid storage 5 and the permeable membrane assembly 7 The connecting pipeline is equipped with the seventh peristaltic pump 22, and the connecting pipeline of the permeable membrane assembly 7 and the fluid reservoir 6 is equipped with the eighth peristaltic pump 23, and the permeable membrane assembly 7 is made up of a forward osmosis membrane, and the effective area of the forward osmosis membrane is 30cm ² , and the runner depth is 2mm.

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

Above-mentioned 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 value tester 20, the sixth peristaltic pump The pump 21 , the seventh peristaltic pump 22 , the eighth peristaltic pump 23 and the agitator 24 are all assemblies of existing equipment, so the specific models and specifications are not described in detail.

The method for recycling carbon, nitrogen, phosphorus and water in sewage provided by the present invention is as follows:

Step 1. The urban sewage enters the water collection tank 1 through the sewage pipe network, and the sewage entering the water collection tank 1 passes through the grille 9 to intercept most of the suspended solids and floating objects, and then enters the grit chamber 2 through the lift pump 10;

Step 2. The sewage entering the grit chamber 2 is pumped into the first reactor 3 for treatment. The first reactor 3 is provided with an ultrafiltration membrane assembly 7 and aeration stones 13, which are filtered by the ultrafiltration membrane assembly 7 and separated out. The water is pumped into the raw material liquid storage tank 5, and the concentrated liquid processed by the first reactor 3 is rich in the separated organic matter and enters the second reactor 4 through the pipeline for anaerobic digestion to produce methane;

Step 3, the water inflow in the raw material liquid storage 5 is used as the raw material liquid, and the high-salt solution of the main component KCl in the commonly used agricultural fertilizer potash is used as the drawing liquid in the drawing liquid storage 6, along with the operation of the forward osmosis system, the use of high and low The osmotic pressure difference makes the raw material liquid in the raw material liquid storage 5 continuously enter the drawing liquid storage 6 through the osmotic membrane assembly 7, and the diluted drawing liquid can be directly used in farmland irrigation to realize the irrigation and reuse of water resources. The nitrogen and phosphorus resources in the concentrated raw material liquid in the liquid storage container 5 are continuously concentrated and enriched and then enter the sedimentation tank 8;

Step 4. The concentrated solution entering the sedimentation tank 8 is adjusted to the pH value and the ratio of nitrogen, magnesium and phosphorus to generate struvite precipitation in the sedimentation tank 8, which is recycled as slow-release fertilizer, and the supernatant in the sedimentation tank 8 is pumped again. Return to the second reactor 4 for anaerobic digestion to achieve complete recovery of carbon resources;

Step 5. After the anaerobic digestion in the second reactor 4 produces methane, the residual nitrogen and phosphorus resources can be continuously recovered, and the supernatant in the second reactor 4 is returned to the raw material liquid storage 5 for reprocessing and utilization. .

The grit chamber 2 in step 1 is an aerated grit chamber.

The ultrafiltration membrane used in the ultrafiltration membrane module 12 in step 2 is a flat membrane, the effective area of a single membrane is 0.1m ² , the size of the membrane sheet is length×width×height=320×220×5mm ³ , the pore size 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 module 7 in step 3 belongs to an asymmetric membrane, which is composed of an active layer and a support layer, wherein the material of the active layer is triacetate fiber, the material of the support layer is polyester, and the effective area of the forward osmosis membrane is 30cm ² , the runner depth is 2mm.

The struvite in step 4 is a slow-release fertilizer, the ratio of Mg:N:P is 1:1:1, and the pH value is controlled at 5-9.5, which is beneficial to the formation of this compound fertilizer.

The working principle of the present utility model:

The urban sewage enters the sump 1 through the municipal pipe network. After the sewage passes through the grille 9 to intercept most of the suspended matter and floating matter, it enters the grit chamber 2 through the lift pump 10 . The effluent quality of grit chamber 2: COD concentration is 270mg/L, TN concentration is 56.9mg/L, NH ₄ ⁺ -N concentration is 47.8mg/L, TP concentration is 4.9mg/L, PO ₄ ^3- -P concentration is 4.14mg/L.

Then, the effluent from the grit chamber 2 enters the first reactor 3 through the first peristaltic pump 11 , and the first reactor 3 is provided with an ultrafiltration membrane module 12 and an aeration stone 13 . The effective area of the ultrafiltration membrane in the ultrafiltration membrane module 12 is 0.1 m ² , the size of the membrane sheet is length×width×height=320×220×5 mm ³ , and the membrane pore size is 0.1 μm. After the operation, a concentrated solution of 1/11.5 of the original water volume is obtained, and 10.5/11.5 of the ultrafiltration membrane module 12 is effluent. While realizing the low-carbon recovery of the suspended solids and colloidal organic matter in the sewage, the membrane effluent rich in nitrogen and phosphorus is obtained, and the concentrate in the first reactor 3 enters the second reactor 4 anaerobic through the second peristaltic pump 14 Digestion produces methane to realize energy recovery; the effluent of the ultrafiltration membrane module 12 in the first reactor 3 is free from solid substances and pathogens and is rich in nitrogen and phosphorus elements, and enters the raw material liquid storage 5 through the third peristaltic pump 15 to recover sewage. Medium nitrogen and phosphorus resources. During the operation, parameters such as the aeration rate of 50 L/h, the temperature of 25° C., and the flux of 20 LMH in the first reactor 3 were controlled. The cleaning method of the ultrafiltration membrane in the ultrafiltration membrane module 12 is simple and convenient. The organic matter on the membrane is gently scraped off and returned to the concentrated solution, and then the membrane surface is cleaned with a certain volume of pure water, and the cleaning solution is returned to the concentrated solution. Then rinse the membrane surface with water until no obvious residual pollutants can be seen. Finally, soak it with sodium hypochlorite solution (available chlorine concentration 2000mg/L) for 2 hours, and then rinse the residual chemical agent on the membrane surface with water to restore 75% of the original state. The recovery rate of carbon resources can reach about 80%. The concentration of COD in the effluent of the ultrafiltration section is 42.89mg/L, the concentration of TN is 24.3mg/L, the concentration of NH ₄ ⁺ -N is 16.5mg/L, the concentration of TP is 6.43mg/L, and the concentration of PO ₄ ^3- -P is 6.4mg /L.

The effluent in the raw material liquid storage 5 is introduced into the permeable membrane module 7 through the seventh peristaltic pump 22 . In the forward osmosis process of the osmotic membrane module 7, the feed water of the raw material liquid storage 5 is used as the raw material liquid, and the high-salt solution of the main component KCl in the commonly used agricultural fertilizer potash is used as the drawing liquid in the drawing liquid storage 6, and the raw material liquid and the The drawing liquid enters the osmotic membrane assembly 7 through the seventh peristaltic pump 22 and the eighth peristaltic pump 23 respectively, and then returns to the raw material liquid storage 5 and the drawing liquid storage 6 respectively, and the volume of the concentrated solution is 1/10 of the raw material liquid. . Utilize the high and low osmotic pressure difference, the water in the raw material liquid storage 5 enters into the drawing liquid storage 6 through the permeable membrane module 7 continuously, and the effective area of the forward osmosis membrane in the permeable membrane module 7 is 30cm ² (50mm×60mm), flow The track depth is 2mm. The diluted drawing liquid in the drawing liquid 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 Concentrated and enriched continuously for subsequent struvite recovery. A conductivity meter 19 and a pH value tester 20 are installed in the raw material liquid reservoir 5 . During the operation, parameters such as cross-flow velocity of 15 cm/s, temperature of 25 °C, and concentration of drawn liquid of 2 mol/L were controlled. After the operation of the forward osmosis membrane in the permeable membrane module 7 is completed, the membrane pollution is small and easy to clean, and the membrane flux can be recovered by more than 75% after only 15 minutes of physical cleaning (gas-water ratio: 240L/h: 40L/h). The COD concentration of the concentrate in the forward osmosis section is 220.88mg/L, the TN concentration is 123.93mg/L, the NH ₄ ⁺ -N concentration is 84.15mg/L, the TP concentration is 57.23mg/L, and the PO ₄ ^3- -P concentration is 56.96 mg/L.

The concentrated liquid in the raw material liquid storage 5 enters the sedimentation tank 8 through the sixth peristaltic pump 21 for chemical precipitation of struvite. A pH value tester 20 and a stirrer 24 are provided in the sedimentation tank 8 . The pH value was adjusted to 9.2, the reaction time was 20min, n(NH ₄ ⁺ ):n(Mg ²⁺ ):n(PO ₃ ^4- ) was 4:1.2:1, the stirring speed was 200rpm, and the precipitation time was 1h After collecting the supernatant, the precipitated part was dried at 40°C for 48h. The nitrogen and phosphorus resources in the sewage are continuously concentrated and exist in the form of struvite precipitation, which can be recycled as slow-release fertilizers to realize the recovery of nitrogen and phosphorus resources. The nitrogen recovery rate is over 80% and the phosphorus recovery rate is over 75%. The content of available phosphorus in the recovered phosphorus product is over 15%. The COD concentration of the supernatant in sedimentation tank 8 is 220.88 mg/L, the TN concentration is 48.35 mg/L, the NH ₄ ⁺ -N concentration is 12.44 mg/L, the TP concentration is 10.31 mg/L, and the PO ₄ ^3- -P concentration is 10.2mg/L.

The supernatant of the sedimentation tank 8 enters the second reactor 4 through the fifth peristaltic pump 18 for anaerobic digestion to produce methane. After anaerobic digestion to produce methane, the gas production capacity is collected to realize the recovery of carbon resources; the sediment can be directly treated as solid waste. Since the nitrogen and phosphorus resources in the concentrated solution of the ultrafiltration section and the supernatant liquid of the struvite recovery section have not been completely recovered, the supernatant liquid after anaerobic digestion and methane production in the second reactor 4 is returned to the raw material liquid through the fourth peristaltic pump 17 Storage 5, continue to concentrate and enrich.

Claims (5)

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.

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