Pig farm sewage treatment system and method
By combining wastewater treatment systems and methods, the problem of wastewater treatment in the liquid foam manure process was solved, resource recovery and deep purification were achieved, and the safety of the pigsty environment and the recycling of resources were ensured.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-03
- Publication Date
- 2026-04-14
AI Technical Summary
Existing liquid foam septic tank wastewater treatment processes suffer from problems such as high concentrations of organic matter, nutrients, and suspended solids, irregular drainage, low anaerobic efficiency, resource waste, and harmful gas emissions. Furthermore, they lack advanced treatment capabilities, making it difficult to achieve resource recovery and water quality compliance.
The process employs a combination of a chemical mixing tank, a solid-liquid separator, an equalization tank, a HiRAD anaerobic reactor, a reaction sedimentation tank, a water quality equalization tank, an SBR biological treatment tank, and a C-MBR biological treatment tank. It recovers nitrogen and phosphorus resources through the MAP process, produces biogas using the HiRAD anaerobic reactor, and combines the deep treatment of SBR and C-MBR to achieve wastewater purification and resource recovery.
This method maximizes the conversion of organic carbon in wastewater into methane resources, avoids the emission of toxic gases, ensures the hygiene of pigsties, and ensures that the purified wastewater meets reuse standards, thus enabling the recycling of resources.
Smart Images
Figure CN121850260A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of wastewater treatment technology for livestock farms, and specifically relates to a wastewater treatment system and method for pig farms. Background Technology
[0002] Currently, the main pig farming methods are water flushing, dry cleaning, and liquid foaming. Among them, the liquid foaming process can remove feces and urine in the pigsty in a timely and effective manner, reduce the labor input in the process of cleaning manure and sewage, reduce the amount of water used for flushing, and improve the level of automated management of the farm. The liquid foaming process is a modification of the water flushing process. The process flow is to inject a certain amount of water into the manure ditch in the pigsty, and discharge the manure, urine, flushing and feeding management water into the manure ditch under the slatted floor. After a certain period of storage, when the manure ditch is full, the gate is opened to discharge the manure water in the ditch. The manure water flows into the main manure ditch and enters the underground manure storage tank or is pumped to the ground manure storage tank. The wastewater discharged from the liquid foaming pig farming process has the following characteristics: (1) High concentration of organic matter. The manure, urine, flushing and feeding management water in the pigsty are discharged into the manure tank under the pigsty and stay in the manure tank for more than 15 days. All the soluble organic matter in the manure and the soluble organic matter from the hydrolysis of the manure enter the wastewater. (1) The wastewater contains a large amount of organic matter, with COD reaching 25,000 mg / L and BOD reaching 18,000 mg / L. (2) High nutrient concentration. The wastewater contains all the pig manure and urine, with total nitrogen concentration reaching 3,500 mg / L and ammonia nitrogen concentration reaching 100 mg / L. (3) High suspended solids concentration. Due to the long-term soaking of manure in water, dissolution and hydrolysis occur, resulting in complete mixing of water and manure, and the suspended solids concentration of the wastewater reaches 20,000 mg / L. (4) Irregular drainage and large fluctuations in water quality. Because the wastewater discharge pattern of pig farms is closely related to working hours, the water volume is large during the flushing time, while the wastewater discharge volume is relatively small at other times, so the concentration of wastewater flowing out of pig farms at different times also varies greatly.
[0003] The advantages of liquid foam manure treatment are that it saves water compared to water flushing, significantly reducing sewage discharge. The disadvantages are: because manure remains in the pigsty for extended periods, anaerobic fermentation occurs, producing large amounts of harmful gases such as sulfur dioxide, ammonia, and methane, deteriorating the indoor air quality and endangering the health of animals and staff. The pollutant concentration in the manure-water mixture is also higher, making post-treatment more difficult, and the infrastructure investment and energy consumption for wastewater treatment are also higher.
[0004] The traditional "liquid foaming sludge" wastewater treatment process is as follows: collection tank → solid-liquid separation → equalization tank → anaerobic tank (ordinary UASB) → aerobic tank (activated sludge process) → coagulation sedimentation (PAC+PAM) → disinfection → discharge / reuse. It has the following drawbacks: ① Nitrogen and phosphorus not recovered: N / P is removed solely through end-of-pipe coagulation and sedimentation (discharged as sludge), without recovering struvite (organic fertilizer) through MAP crystallization; ② Low anaerobic efficiency: Conventional UASB has poor treatment effect on high concentrations of organic matter (COD>20000mg / L) and low methane yield; ③ Insufficient advanced treatment: Simple coagulation is only performed after the aerobic tank, making it difficult for the effluent SS and COD to consistently meet standards for reuse; ④ Resource waste: Biogas is not effectively collected for power generation, and nitrogen and phosphorus are disposed of in the form of sludge, which is costly. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention discloses a wastewater treatment system and method for pig farms. After recovering resources from the wastewater, the remaining pollutants in the wastewater are then purified as needed to achieve water quality standards.
[0006] The first aspect of this invention aims to provide a wastewater treatment system for pig farms, comprising: The chemical mixing tank is used to fully mix the wastewater and the phosphorus and nitrogen removal agents, promote the formation of struvite, and enrich it on the fibers (pig manure has a complex composition, containing a large amount of colloidal substances, and the solids obtained after solid-liquid separation are fibrous). Solid-liquid separator, used to separate solids and liquids in a dosing mixing tank; An equalization tank is used to store wastewater after solid-liquid separation and to achieve homogenization and equalization of wastewater discharge by regulating the wastewater discharge rate. The HiRAD anaerobic digester has its inlet connected to the outlet of the equalization tank, and is used to perform anaerobic digestion on the effluent from the equalization tank to remove most of the organic matter in the wastewater and produce biogas. The reaction sedimentation tank has its inlet connected to the outlet of the HiRAD anaerobic reactor, and is used to further remove nitrogen and phosphorus from the effluent of the HiRAD anaerobic reactor. A water quality conditioning tank, with its inlet connected to the outlet of the reaction sedimentation tank, is used to adjust the pH of the effluent from the reaction sedimentation tank. The SBR biological treatment tank has an inlet connected to the outlet of the water quality conditioning tank, and is used to remove organic matter, nitrogen and phosphorus from the effluent of the water quality conditioning tank. The C-MBR biological treatment tank has its inlet connected to the outlet of the SBR biological treatment tank, and is used to remove COD and perform guaranteed phosphorus and nitrogen removal from the effluent of the SBR biological treatment tank. The disinfection tank has its inlet connected to the outlet of the C-MBR biological treatment tank and is used to disinfect the effluent from the C-MBR biological treatment tank. The water recycling tank has its inlet connected to the outlet of the disinfection tank, and is used to collect the effluent from the disinfection tank.
[0007] As a further improvement of the present invention, the phosphorus and nitrogen removal agent is selected from the first agent or the second agent; the first agent includes lime, magnesium chloride and potassium dihydrogen phosphate; wherein the amount of lime added is 5 kg / m³. 3 (kg / m 3 This refers to adding 5 kg of chemicals per cubic meter of wastewater (the same applies below); the amount of magnesium chloride added is 3 kg / m³. 3 (Calculated as MgCl2·6H2O); the amount of potassium dihydrogen phosphate added is 2 kg / m³. 3 (Calculated as KH2PO4); the second reagent includes lime, magnesium chloride, sodium phosphate, and polyferric sulfate; wherein the amount of lime added is 4 kg / m³. 3 The amount of magnesium chloride added is 3 kg / m³. 3 (Calculated as MgCl2·6H2O); the amount of sodium phosphate added is 2 kg / m³. 3 (Calculated as Na3PO4); the amount of polyferric sulfate added is 1 kg / m³. 3 .
[0008] In this invention, the selection of the first or second agent is determined based on the phosphorus and nitrogen content in the wastewater.
[0009] Specifically, when the total phosphorus (TP) concentration in wastewater is low (e.g., TP < 50 mg / L) or the pH is acidic (pH 6-7), the first reagent should be used preferentially. In this case, potassium dihydrogen phosphate (KH2PO4) has good water solubility and can provide PO4 in the acidic environment. 3- The pH is adjusted to 9-10 with lime (Ca(OH)2) to promote MAP (struvite) crystallization; magnesium chloride (MgCl2) provides Mg. 2+ This ensures efficient recovery of nitrogen and phosphorus.
[0010] When the total phosphorus (TP) concentration in wastewater is high (e.g., TP ≥ 50 mg / L) or when enhanced flocculation and sedimentation are required, the second agent should be selected. Sodium phosphate (Na3PO4) is strongly alkaline and can neutralize acidic wastewater and provide PO4. 3- Polyferric sulfate (PFS) is used as a flocculant to enhance the entrapment and sweeping effect of MAP crystallization, thereby improving solid-liquid separation. Lime is still used to adjust the pH to 9.5-10, and the dosage of magnesium chloride is the same as that of the first reagent (to ensure Mg...). 2+ adequate).
[0011] Impact of nitrogen content: Regardless of the reagent used, the dosage of MgCl2 must be adjusted according to the total nitrogen (TN) concentration (the higher the TN, the slightly increased Mg2+ dosage ratio should be 1.5:1) to ensure NH4+ concentration. + Fully settle.
[0012] In response to the current situation of wastewater discharge from "vaporized manure" farms, this invention employs a comprehensive resource recovery approach to treat nitrogen (N) and phosphorus (P) in the wastewater. Since high concentrations of ammonia nitrogen are toxic to anaerobic microorganisms, to ensure anaerobic efficiency while simultaneously recovering N and P, the mixed pig manure and urine undergoes a MAP (magnesium ammonium phosphate) process for nitrogen and phosphorus removal. The MAP crystals formed during denitrification and phosphorus removal are enriched on the fibers in the manure and urine, and are removed from the wastewater along with suspended solids (SS). This not only ensures the ammonia nitrogen concentration in the wastewater entering the anaerobic biological treatment tank but also recovers N and P as a highly efficient slow-release organic fertilizer. In addition to ammonia nitrogen, the total nitrogen in the wastewater also includes organic nitrogen. Anaerobic microorganisms convert organic nitrogen into ammonia nitrogen during protein decomposition; therefore, the effluent from the anaerobic biological treatment contains a certain amount of ammonia nitrogen. To further denitrify, reduce the COD / N ratio adjustment pressure required for advanced biological denitrification, and recover N and P resources, a second chemical precipitation method is used to denitrify the anaerobic effluent. The MAP precipitate formed during denitrification serves as raw material for organic composting.
[0013] The mechanism of denitrification is as follows: As a further improvement of the present invention, sludge containing anaerobic bacteria is added to the HiRAD anaerobic reactor.
[0014] The sludge containing anaerobic bacteria was obtained by culturing the sediment from the septic tanks of local pig farms. The masterbatch cultured from the sedimentation of septic tanks in the same area contains anaerobic bacterial communities, which are better adapted to the wastewater environment of local pig farms, thereby greatly improving the efficiency of anaerobic digestion and methanogenesis.
[0015] As a further improvement of the present invention, the reaction sedimentation tank is composed of a reaction tank and a sedimentation tank; the reaction tank is a corridor-type aerated mixing reaction tank; the sedimentation tank is a horizontal flow sedimentation tank; and the sludge at the bottom of the sedimentation tank is discharged by static pressure.
[0016] As a further improvement of the present invention, the phosphorus and nitrogen removal agent added to the reaction sedimentation tank is lime at a dosage of 2 kg / m³. 3 The amount of sulfuric acid added is 1 kg / m³. 3 The amount of MgCl2 added is 3 kg / m 3 (Based on MgCl2·6H2O), the amount of Na3PO4 added is 2 kg / m³. 3 .
[0017] As a further improvement of the present invention, sulfuric acid is used in the water quality conditioning tank to adjust the pH value of the wastewater to neutral.
[0018] As a further improvement of the present invention, limestone powder, a dephosphorizing agent, is added to the SBR biological treatment tank for dephosphorization, at a dosage of 50 kg / m³. 3(Based on dry weight).
[0019] As a further improvement of the present invention, the reagents added to the C-MBR biochemical tank are sodium hypochlorite and a cleaning agent.
[0020] As a further improvement of the present invention, the disinfection tank utilizes a chlorine dioxide generator to purge chlorine dioxide, with a dosage of 300g / h of available chlorine.
[0021] A second aspect of the present invention provides a method for treating wastewater from pig farms, comprising the following steps: Wastewater from pig farms is introduced into a dosing and mixing tank to add phosphorus and nitrogen removal agents, which promote the formation of struvite and enrich the struvite onto the fibers. After solid-liquid separation, the effluent is introduced into an equalization tank, where acid is added to adjust the pH to neutral. The effluent is introduced into the HiRAD anaerobic digester, where anaerobic microorganisms are added to carry out anaerobic digestion. The effluent is introduced into a reaction sedimentation tank, where phosphorus and nitrogen removal agents are added again for further phosphorus and nitrogen removal. The effluent is introduced into a water quality conditioning tank, where sulfuric acid is added to adjust the pH to neutral. The effluent is introduced into the SBR biological treatment tank, where a dephosphorizing agent is added to remove most of the organic matter, nitrogen, and phosphorus. The effluent is introduced into a C-MBR biological treatment tank to remove COD and perform guaranteed phosphorus and nitrogen removal from the effluent of the SBR biological treatment tank. The effluent is disinfected to complete the sewage treatment.
[0022] The present invention has at least the following technical effects: The system and method of this invention can effectively purify wastewater discharged from pig farms using the "liquid foam manure" process. It maximizes the conversion of organic carbon in the wastewater into methane, transforming it into a high-quality biomass resource. This not only turns waste into treasure but also avoids the emission of toxic gases, ensuring cleanliness and hygiene in pigsties and preventing the infection and spread of diseases. Simultaneously, it converts a large amount of nutrients in the wastewater, such as nitrogen and phosphorus, into organic fertilizer. The purified wastewater undergoes deep cleaning, meeting reuse standards and achieving resource recycling.
[0023] Specifically, the advancements of the system and method of this invention are as follows: (1) Maximizing resource recovery: Two MAP processes (dosing mixing tank + reaction sedimentation tank) recover nitrogen and phosphorus (struvite as organic fertilizer), and the HiRAD anaerobic digester produces biogas (methane purity 70-74%) for power generation, realizing "turning waste into treasure"; (2) High-efficiency anaerobic digestion: HiRAD anaerobic digester + localized anaerobic bacteria sludge, COD removal rate >95% (23522.5→1176.13mg / L), methane production rate is significantly higher than that of traditional UASB; (3) Deep treatment ensures reuse: SBR+CC-MBR combined process (SBR denitrification and phosphorus removal, C-MBR guaranteed denitrification and phosphorus removal + membrane filtration), effluent SS <12mg / L, COD <55mg / L, stably meeting the GB / T18920-2002 reuse standard; (4) Avoid secondary pollution: The closed anaerobic system reduces the emission of toxic gases (ammonia, methane), and the fibrous solids (including struvite) after solid-liquid separation can be used directly as composting raw materials without generating hazardous waste. Attached Figure Description
[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a process flow diagram of an embodiment of the present invention. Detailed Implementation
[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0026] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0027] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0028] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0029] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0030] This invention discloses a wastewater treatment system for pig farms, comprising: The chemical mixing tank is used to ensure thorough mixing of wastewater and phosphorus and nitrogen removal agents, promoting the formation of struvite and its accumulation on fibers; Solid-liquid separator, used to separate solids and liquids in a dosing mixing tank; An equalization tank is used to store wastewater after solid-liquid separation and to achieve homogenization and equalization of wastewater discharge by regulating the wastewater discharge rate. The HiRAD anaerobic digester has its inlet connected to the outlet of the equalization tank, and is used to perform anaerobic digestion on the effluent from the equalization tank to remove most of the organic matter in the wastewater and produce biogas. The reaction sedimentation tank is connected to the HiRAD anaerobic digester outlet via its inlet, and is used to further remove nitrogen and phosphorus from the HiRAD anaerobic digester effluent. A water quality conditioning tank, with its inlet connected to the outlet of the reaction sedimentation tank, is used to adjust the pH of the effluent from the reaction sedimentation tank. The SBR biological treatment tank has an inlet connected to the outlet of the water quality conditioning tank, and is used to remove organic matter, nitrogen and phosphorus from the effluent of the water quality conditioning tank. The C-MBR biological treatment tank has its inlet connected to the outlet of the SBR biological treatment tank, and is used to remove COD and perform guaranteed phosphorus and nitrogen removal from the effluent of the SBR biological treatment tank. The disinfection tank has its inlet connected to the outlet of the C-MBR biological treatment tank and is used to disinfect the effluent from the C-MBR biological treatment tank. The water recycling tank has its inlet connected to the outlet of the disinfection tank, and is used to collect the effluent from the disinfection tank.
[0031] In some embodiments of the present invention, the phosphorus and nitrogen removal agent is selected from a first agent or a second agent; the first agent includes lime, magnesium chloride, and potassium dihydrogen phosphate; wherein the amount of lime added is 5 kg / m³. 3 The amount of magnesium chloride added is 3 kg / m³. 3 (Calculated as MgCl2·6H2O); the amount of potassium dihydrogen phosphate added is 2 kg / m³. 3(Calculated as KH2PO4); the second reagent includes lime, magnesium chloride, sodium phosphate, and polyferric sulfate; wherein the amount of lime added is 4 kg / m³. 3 The amount of magnesium chloride added is 3 kg / m³. 3 (Calculated as MgCl2·6H2O); the amount of sodium phosphate added is 2 kg / m³. 3 (Calculated as Na3PO4); the amount of polyferric sulfate added is 1 kg / m³. 3 .
[0032] In this invention, the selection of the first or second agent is determined based on the phosphorus and nitrogen content in the wastewater.
[0033] In response to the current situation of wastewater discharge from "vaporized manure" farms, this invention employs a comprehensive resource recovery approach to treat nitrogen (N) and phosphorus (P) in the wastewater. Since high concentrations of ammonia nitrogen are toxic to anaerobic microorganisms, to ensure anaerobic efficiency while simultaneously recovering N and P, the mixed pig manure and urine undergoes a MAP (magnesium ammonium phosphate) process for nitrogen and phosphorus removal. The MAP crystals formed during denitrification and phosphorus removal are enriched on the fibers in the manure and urine, and are removed from the wastewater along with suspended solids (SS). This not only ensures the ammonia nitrogen concentration in the wastewater entering the anaerobic biological treatment tank but also recovers N and P as a highly efficient slow-release organic fertilizer. In addition to ammonia nitrogen, the total nitrogen in the wastewater also includes organic nitrogen. Anaerobic microorganisms convert organic nitrogen into ammonia nitrogen during protein decomposition; therefore, the effluent from the anaerobic biological treatment contains a certain amount of ammonia nitrogen. To further denitrify, reduce the COD / N ratio pressure required for advanced biological denitrification, and recover N and P resources, a second chemical precipitation method is used to denitrify the anaerobic effluent. The MAP precipitate formed during denitrification is used as raw material for organic composting.
[0034] The mechanism of denitrification is as follows: In some embodiments of the present invention, sludge containing anaerobic bacteria is added to the HiRAD anaerobic reactor.
[0035] The sludge containing anaerobic bacteria was obtained by culturing sediment from the septic tanks of a local pig farm. Anaerobic microorganisms cultivated in the sludge decompose organic matter in wastewater into organic acids, achieving acidification and degradation, and further degradation to produce methane. Anaerobic biochemical treatment can simultaneously achieve the dual purpose of decomposing organic matter in wastewater and producing methane, thus recovering energy. Due to the strong vitality of anaerobic microorganisms, it is suitable for treating high-concentration wastewater. HiRAD high-efficiency anaerobic technology was specifically developed to address many shortcomings of existing anaerobic technologies. Its main features are high efficiency, low cost, ease of operation, no secondary pollution, emission reduction, and energy saving. The methane purity of the biogas produced in this stage can reach 70-74%, far exceeding that of current conventional technologies.
[0036] In some embodiments of this invention, a high-efficiency spiral separator is selected as the solid-liquid separator to achieve effective separation of wastewater. Optional high-efficiency separation equipment includes FAN (a German brand high-efficiency spiral separator with spiral extrusion solid-liquid separation function, suitable for large-scale livestock farm manure treatment) or FINRONE (another high-efficiency spiral separator, similar to FAN, both being solid-liquid separation devices based on the spiral extrusion principle, suitable for the solid-liquid separation stage in wastewater treatment processes). Traditional solid-liquid separation equipment, such as bar screens and cadmium slag devices, are mainly used to separate and remove large particulate matter, with poor suspended solids separation effect.
[0037] In some embodiments of the present invention, the reaction sedimentation tank consists of a reaction tank and a sedimentation tank; the reaction tank is a corridor-type aerated mixing reaction tank; the sedimentation tank is a horizontal flow sedimentation tank; and the sludge at the bottom of the sedimentation tank is discharged by static pressure.
[0038] In some embodiments of the present invention, the phosphorus and nitrogen removal agent added to the reaction sedimentation tank is lime at a dosage of 2 kg / m³. 3 The amount of sulfuric acid added is 1 kg / m³. 3 The amount of MgCl2 added is 3 kg / m 3 (Based on MgCl2·6H2O), the amount of Na3PO4 added is 2 kg / m³. 3 In addition to ammonia nitrogen, total nitrogen in wastewater also includes organic nitrogen. Anaerobic microorganisms convert organic nitrogen into ammonia nitrogen during protein decomposition, resulting in a certain amount of ammonia nitrogen in the anaerobic biological effluent. To further denitrify, reduce the COD / N ratio pressure required for advanced biological denitrification, and recover N and P resources, a second chemical precipitation method was used to denitrify the anaerobic effluent. Mg salt was added to generate precipitates, removing N and P from the wastewater. This reduces the ammonia nitrogen concentration in subsequent biological treatments and decreases the COD consumption due to ammonia nitrogen degradation. Unlike chemical mixing tanks, a sedimentation tank is required to separate the produced precipitates. Since MAP crystallization requires a long time, unlike traditional flocculation sedimentation, the reaction tank in this invention requires a sufficient retention time (>20 min) and pH control at 9.5-10 to form MAP crystals, while avoiding competition from magnesium hydroxide precipitation at pH > 10.
[0039] In some embodiments of the present invention, sulfuric acid is used in the water quality conditioning tank to adjust the pH value of the wastewater to the neutral range.
[0040] In some embodiments of the present invention, limestone powder, a dephosphorizing agent, is added to the SBR biological treatment tank for dephosphorization, with an addition amount of 50 kg / m³. 3 (Based on dry weight).
[0041] In some embodiments of the present invention, the agents added to the C-MBR biochemical tank are sodium hypochlorite and cleaning agent.
[0042] In some embodiments of the present invention, the disinfection pool is supplied with chlorine dioxide using a chlorine dioxide generator, with a dosage of 300g / h of available chlorine.
[0043] This invention also discloses a method for treating wastewater from pig farms, comprising the following steps: S1. Introduce wastewater from the pig farm into a dosing and mixing tank and add phosphorus and nitrogen removal agents to promote the formation of struvite and enrich the struvite onto the fibers. S2. After solid-liquid separation, the effluent is introduced into the equalization tank, and acid is added to adjust the pH to neutral; S3. The effluent is introduced into the HiRAD anaerobic digester, where anaerobic microorganisms are added to carry out anaerobic digestion. S4. The effluent is introduced into the reaction sedimentation tank, and phosphorus and nitrogen removal agents are added again for further phosphorus and nitrogen removal; S5. The effluent is introduced into a water quality conditioning tank, and sulfuric acid is added to adjust the pH to neutral. S6. The effluent is introduced into the SBR biological treatment tank, where a dephosphorizing agent is added to remove most of the organic matter, nitrogen, and phosphorus; S7. The effluent is introduced into the C-MBR biological treatment tank to remove COD and perform guaranteed phosphorus and nitrogen removal in the effluent from the SBR biological treatment tank; S8. Disinfect the effluent to complete the sewage treatment.
[0044] It should be noted that any aspects not described in detail in the embodiments of the present invention are existing technologies and are not the main inventive points, and will not be elaborated upon further.
[0045] Unit definition: kg / m³ refers to the mass (dry weight) of the reagent added per cubic meter of wastewater.
[0046] Example 1 A wastewater treatment system for pig farms, such as Figure 1 As shown, it includes, in sequence, a water collection tank, a chemical mixing tank, a solid-liquid separator, an equalization tank, a HiRAD anaerobic reactor, a reaction sedimentation tank, a water quality equalization tank, an SBR biological treatment tank, a C-MBR biological treatment tank (MBR membrane reactor), a disinfection tank, and a reclaimed water tank.
[0047] The parameters for each process are as follows: (1) Dosing and mixing tank: hydraulic retention time: HRT=60min; lime dosage 5 kg / m³ (calculated as Ca(OH)2), MgCl2 dosage 3 kg / m³ (calculated as MgCl2·6H2O), KH2PO4 dosage 2 kg / m³; agitator speed 4 rpm; (2) Solid-liquid separator: spiral separator, power 7.5kW; (3) Equalization tank: Hydraulic retention time: HRT=10h; Flow rate: Q=20.83m³ 3 / h; add sulfuric acid to adjust to the neutral range (pH 6~8, the same below); (4) HiRAD Anaerobic Reactor: Anaerobic reactor, HiRAD-150; Influent COD concentration: 23522.5 mg / L; Effluent COD concentration: 1176.12 mg / L; COD reduction concentration: 22346.38 mg / L; Flow rate: Q=500 m³ / L 3 / d; COD reduction: =22346.38mg / L 500m 3 / d=11173.19kg / d; Total biogas production: 5586m³ 3 / d, methane purity 70-74%; (5) Reaction sedimentation tank: hydraulic retention time: HRT=40min; surface loading: q=0.8m 3 / m 2 • h; Equipped with a frame agitator, stirring speed 10 rpm; pH online controller ensures pH is maintained between 9.5 and 10; Dosing system dosage: lime 2 kg / m³ 3 Sulfuric acid 1 kg / m 3 MgCl2 3 kg / m 3 Na3PO4 2 kg / m 3 ; (6) Equalization tank: hydraulic retention time: HRT=25min; equipped with an online pH controller to maintain pH in the neutral range by adding sulfuric acid; (7) SBR biological treatment: Influent flow rate: Q=500m³ 3 / d=20.83m 3 / h; Influent water quality: COD=1176.13mg / L, BOD=677.45mg / L, T-N=176.63mg / L, NH3-N=109.13 mg / L, T-P=12mg / L; Effluent water quality: COD=235.23mg / L, BOD=101.62mg / L, T-N=61.82mg / L, NH3-N=25.1mg / L, T-P=3mg / L; (8) C-MBR biological treatment tank: water treatment capacity: Q=20.83m³ 3 / h; Sludge concentration: 5000 mg / L; Hydraulic retention time: HRT=12h; NaClO dosing pump flow rate: 44L / hr; Cleaning agent (citric acid) dosing pump flow rate: 128L / hr; (9) Disinfection tank: Equipped with a chlorine dioxide dosing system Jet-50, the chlorine dioxide generator circulates chlorine dioxide, the dosing rate is 300g / h; hydraulic retention time: HRT=60min.
[0048] The wastewater treatment process using the above system is as follows: S1. The wastewater from the pig farm (temporarily stored in the collection tank) is introduced into the dosing and mixing tank and phosphorus and nitrogen removal agent (MAP agent) is added to promote the formation of struvite and to enrich the struvite onto the fibers; the suspended solids concentration in the wastewater is: SS=20000mg / L, total nitrogen is: 3600mg / L; the amount of nitrate nitrogen removed is 90%, the amount of ammonium nitrogen removed is: 1350kg / d, 1kg of nitrogen removed generates 17.43kg of struvite (MAP), and 23530.5kg of struvite (MAP) is generated every day; S2. After solid-liquid separation, the effluent is introduced into the equalization tank, and sulfuric acid is added to adjust the pH to neutral; the wastewater separated by the solid-liquid separator contains SS=1200mg / L; the daily amount of SS entering the subsequent wastewater treatment is 600kg; the solid sediment enters the composting workshop as raw material for organic composting; S3. The effluent is introduced into the HiRAD anaerobic digester, where anaerobic microorganisms are added to carry out anaerobic digestion. The gas produced is biogas, which is purified and stored before entering the biogas generator room to generate electricity. S4. The effluent is introduced into the reaction sedimentation tank, and phosphorus and nitrogen removal agents (lime 2 kg / m³) are added again. 3 Sulfuric acid 1 kg / m 3 MgCl2 3 kg / m 3 Na3PO4 2 kg / m 3 Further phosphorus and nitrogen removal; S5. The effluent is introduced into a water quality conditioning tank, and sulfuric acid is added to adjust the pH to neutral. S6. The effluent is introduced into the SBR biological treatment tank, where a dephosphorizing agent is added to remove most of the organic matter, nitrogen, and phosphorus; S7. The effluent is introduced into the C-MBR biological treatment tank to remove COD and perform guaranteed phosphorus and nitrogen removal. The concentrated water is returned to the SBR biological treatment tank for recirculation. The sludge enters the sludge thickening tank, is dewatered by filter press, and then enters the composting workshop. The filtrate is returned to the equalization tank to participate in the circulation again. S8. Disinfect the effluent to complete the sewage treatment, and store the clean water in the reuse water tank.
[0049] The water quality treatment results for each process are shown in Table 1.
[0050] Table 1 As can be seen from Table 1, all indicators of the clean water treated by Example 1 of the present invention meet the standard requirements.
[0051] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A wastewater treatment system for pig farms, characterized in that, include: The chemical mixing tank is used to ensure thorough mixing of wastewater and phosphorus and nitrogen removal agents, promoting the formation of struvite. Solid-liquid separator, used to separate solids and liquids in a dosing mixing tank; An equalization tank is used to store wastewater after solid-liquid separation and to achieve homogenization and equalization of wastewater discharge by regulating the wastewater discharge rate. The HiRAD anaerobic digester has its inlet connected to the outlet of the equalization tank, and is used to perform anaerobic digestion on the effluent from the equalization tank to remove most of the organic matter in the wastewater and produce biogas. The reaction sedimentation tank has its inlet connected to the outlet of the HiRAD anaerobic reactor, and is used to further remove nitrogen and phosphorus from the effluent of the HiRAD anaerobic reactor. A water quality conditioning tank, with its inlet connected to the outlet of the reaction sedimentation tank, is used to adjust the pH of the effluent from the reaction sedimentation tank. The SBR biological treatment tank has an inlet connected to the outlet of the water quality conditioning tank, and is used to remove organic matter, nitrogen and phosphorus from the effluent of the water quality conditioning tank. The C-MBR biological treatment tank has its inlet connected to the outlet of the SBR biological treatment tank, and is used to remove COD and perform guaranteed phosphorus and nitrogen removal from the effluent of the SBR biological treatment tank. The disinfection tank has its inlet connected to the outlet of the C-MBR biological treatment tank and is used to disinfect the effluent from the C-MBR biological treatment tank. The water recycling tank has its inlet connected to the outlet of the disinfection tank, and is used to collect the effluent from the disinfection tank.
2. The pig farm wastewater treatment system according to claim 1, characterized in that, The phosphorus and nitrogen removal agent is selected from either the first agent or the second agent; the first agent includes lime, magnesium chloride, and potassium dihydrogen phosphate; wherein the amount of lime added is 5 kg / m³. 3 The amount of magnesium chloride added is 3 kg / m³. 3 The amount of potassium dihydrogen phosphate added is 2 kg / m³. 3 The second reagent comprises lime, magnesium chloride, sodium phosphate, and polyferric sulfate; wherein the amount of lime added is 4 kg / m³. 3 The amount of magnesium chloride added is 3 kg / m³. 3 The amount of sodium phosphate added is 2 kg / m³. 3 The amount of polyferric sulfate added is 1 kg / m³. 3 .
3. The pig farm wastewater treatment system according to claim 1, characterized in that, Sludge containing anaerobic bacteria is added to the HiRAD anaerobic reactor.
4. The pig farm wastewater treatment system according to claim 1, characterized in that, The reaction sedimentation tank consists of a reaction tank and a sedimentation tank; the reaction tank is a corridor-type aerated mixing reaction tank; the sedimentation tank is a horizontal flow sedimentation tank; and the sludge at the bottom of the sedimentation tank is discharged by static pressure.
5. The pig farm wastewater treatment system according to claim 1, characterized in that, The phosphorus and nitrogen removal agent added to the reaction sedimentation tank is lime at a dosage of 2 kg / m³. 3 The amount of sulfuric acid added is 1 kg / m³. 3 The amount of MgCl2 added is 3 kg / m 3 The amount of Na3PO4 added is 2 kg / m³. 3 .
6. The pig farm wastewater treatment system according to claim 1, characterized in that, Sulfuric acid is used in the water quality conditioning tank to adjust the pH of the wastewater to neutral.
7. The pig farm wastewater treatment system according to claim 1, characterized in that, Limestone powder, a dephosphorizing agent, is added to the SBR biological treatment tank at a rate of 50 kg / m³. 3 .
8. The pig farm wastewater treatment system according to claim 1, characterized in that, The chemicals added to the C-MBR biological treatment tank are sodium hypochlorite and cleaning agent.
9. The pig farm wastewater treatment system according to claim 1, characterized in that, The disinfection tank uses a chlorine dioxide generator to purge chlorine dioxide, with a dosage of 300g / h of available chlorine.
10. A method for treating wastewater from a pig farm, characterized in that, The wastewater treatment system for pig farms, as described in any one of claims 1 to 9, comprises the following steps: Wastewater from pig farms is introduced into a dosing and mixing tank to add phosphorus and nitrogen removal agents, which promote the formation of struvite and enrich the struvite onto the fibers. After solid-liquid separation by a solid-liquid separator, the effluent is introduced into an equalization tank, where acid is added to adjust the pH to neutral. The effluent is introduced into the HiRAD anaerobic digester, where anaerobic microorganisms are added to carry out anaerobic digestion. The effluent is introduced into a reaction sedimentation tank, where phosphorus and nitrogen removal agents are added again for further phosphorus and nitrogen removal. The effluent is introduced into a water quality conditioning tank, where sulfuric acid is added to adjust the pH to neutral. The effluent is introduced into the SBR biological treatment tank, where a dephosphorizing agent is added to remove most of the organic matter, nitrogen, and phosphorus. The effluent is introduced into a C-MBR biological treatment tank to remove COD and perform guaranteed phosphorus and nitrogen removal from the effluent of the SBR biological treatment tank. The effluent is disinfected to complete the sewage treatment.