Reverse-flow anaerobic fluidized bed reactor
The innovative design of the countercurrent anaerobic fluidized bed reactor solves the problems of sludge loss and long hydraulic retention time, achieving efficient domestic sewage treatment with effluent meeting standards and eliminating the need for a heating system.
Patent Information
- Application Number
- CN202423006244.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-06
- Publication Date
- 2025-10-31
- Estimated Expiration
- 2034-12-06
AI Technical Summary
Existing upflow and expanded anaerobic reactors suffer from problems such as sludge loss, long hydraulic retention time, and poor treatment effect when treating domestic sewage, making it difficult to meet the Class A discharge standard of sewage treatment plants.
A countercurrent anaerobic fluidized bed reactor was designed, which adopts a structure with water inlet at the bottom of the tank, water inlet at the middle, and reflux outlet at the bottom. Combined with a grid and temperature control system, a three-phase separator is used to achieve mud-water separation, and the reaction process is optimized by controlling the reflux velocity and hydraulic residence time.
It achieves clear sludge-water separation, with effluent SS essentially at 0, COD effluent less than 50 mg/L, short hydraulic retention time, small reactor volume, and treatment effect reaching or exceeding the Class A standard of wastewater treatment plants, without the need for high-temperature operation.
Smart Images
Figure CN223496302U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to an anaerobic reactor for treating domestic sewage. Background Technology
[0002] Domestic sewage contains excessive amounts of organic matter, and direct discharge will pollute the environment. However, through the action of anaerobic microorganisms (including facultative anaerobic microorganisms), various complex organic substances in the wastewater are decomposed and transformed into harmless methane and carbon dioxide, thus purifying the sewage and meeting the relevant standards for discharge or utilization of water quality.
[0003] The existing upflow anaerobic reactor (UASB) process involves wastewater sequentially entering the bottom sludge layer and the upper sludge suspension zone through a distribution device. There, it reacts with anaerobic microorganisms to generate biogas. The gas-liquid-solid mixture is then separated by a three-phase separator at the top. Sludge falls back into the sludge suspension zone, and the separated wastewater is discharged from the system, while the generated biogas is recovered. The inlet is located at the bottom of the reactor, and the return outlet is located in the sedimentation zone at the top. This type of reactor requires high-level solid-liquid-gas separation. Optimizing the three-phase separator within the reactor and increasing the height-to-diameter ratio can improve wastewater treatment efficiency; however, this design increases the complexity of the reactor design and results in less than ideal sludge-water separation, leading to sludge loss. Furthermore, existing upflow anaerobic reactors have a relatively long hydraulic retention time (HRT).
[0004] Existing expanded anaerobic granular sludge blanket (EGSB) reactors, based on UASB, increase the aspect ratio to extend settling time and space; improve sludge settling performance by promoting the formation of anaerobic granular sludge; and increase the reflux ratio to improve fluidization velocity, achieving thorough sludge-water mixing. However, this technology has several drawbacks: 1. Difficulty in forming granular sludge; 2. Long start-up time; 3. Long hydraulic retention time; 4. Generally requires a temperature control system to raise the temperature to mesophilic (30–40°C) or hyperthermic (50–60°C); 5. Higher fluidization velocities lead to increased reactor height, sludge loss, and increased design complexity of the three-phase separator; 6. This method is mainly used for high-concentration organic wastewater, and its treatment effect on domestic sewage organic matter is difficult to achieve the Class A discharge standard of wastewater treatment plants (COD less than 50 mg / L), with effluent COD generally ranging from 80 to 100 mg / L. Utility Model Content
[0005] This invention aims to solve the technical problems of sludge loss, long hydraulic retention time, and poor treatment effect in existing anaerobic treatment of domestic sewage, and provides a countercurrent anaerobic fluidized bed reactor.
[0006] The countercurrent anaerobic fluidized bed reactor of this invention includes: a tank 1, an inlet pump 2, and a reflux pump 3;
[0007] The tank body 1 is cylindrical with a conical bottom. Inside the tank body 1, a water distribution device 1-1 is installed in the middle section, a rectifier device 1-2 is installed in the lower section, and a three-phase separator 1-3 is installed in the upper section. The top of the tank body 1 is open, and an overflow weir 1-4 and a drain outlet 1-7 are installed at the top.
[0008] A water inlet 1-5 is provided above the water distribution device 1-1 in the middle section of the side wall of tank 1; the water pump 2 is connected to the water inlet 1-5;
[0009] A water outlet 1-6 is provided at the bottom of the tank 1, and the water outlet 1-6 is connected to the water inlet 1-5 via the return pump 3.
[0010] Furthermore, the countercurrent anaerobic fluidized bed reactor of this invention also includes a screen, which is used for treatment to remove solid waste residue.
[0011] Furthermore, the countercurrent anaerobic fluidized bed reactor of this invention also includes a temperature control system, with an additional insulation layer wrapped around the outside of the tank 1.
[0012] Furthermore, the countercurrent anaerobic fluidized bed reactor of this invention also includes a gas collection device, which is connected to the three-phase separator 1-3.
[0013] The process of treating domestic sewage using the countercurrent anaerobic fluidized bed reactor of this invention is as follows: Anaerobic sludge from the secondary sedimentation tank is added to tank 1, with the sludge layer height being one-third of the inlet height. Domestic sewage is pumped into tank 1 via inlet pump 2 and then flows downwards through distribution device 1-1, allowing the sludge to mix thoroughly in the lower part of the reaction zone and in the return pipe. The mixed liquor suspended solids concentration (MLSS) in the reaction zone is above 5000 mg / L. The return liquid (containing sludge) is returned to inlet 1-5 via outlet 1-6 and return pump 3. The flow velocity in the reaction zone is controlled at 0.2–10 m / h. Simultaneously, due to the presence of inlet water, some water is squeezed upwards and separated, then discharged through three-phase separator 1-3, overflow weir 1-4, and outlet 1-7. The hydraulic retention time (HRT) of the domestic sewage in tank 1 is 3–6 h, and the total organic load is 0.5–2 kg COD·m³. -3 ·d -1 To complete the treatment of domestic sewage.
[0014] The advantages of the countercurrent anaerobic fluidized bed reactor of this invention are as follows:
[0015] 1. Excellent mud-water separation effect: A clear mud-water stratification interface can be formed in the reaction zone, which greatly reduces the design requirements of the three-phase separator and reduces sludge loss. The effluent SS is basically 0.
[0016] 2. Good mud-water mixing effect in the reaction zone: In the reaction zone, the flow rate can be controlled almost arbitrarily, without being limited by the size or height of the reactor. By gradually increasing the reflux rate, it is possible to achieve the upflow velocity of EGSB (above 10m / h) while having a small height-to-diameter ratio, thus reducing the volume of the reactor.
[0017] 3. Excellent reactor performance: When the influent COD is 200-300 mg / L, the effluent COD of existing anaerobic membrane-free reactors is generally 80-100 mg / L. However, the reactor of this invention, without membrane filtration, can achieve an effluent COD below 50 mg / L. The total hydraulic retention time is approximately 6 hours, which is relatively short.
[0018] 4. This utility model's countercurrent anaerobic fluidized bed reactor improves the "solid-liquid mixing" effect in the reaction zone while enhancing the "solid-liquid separation" effect. It can be used in the field of wastewater treatment. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the structure of the countercurrent anaerobic fluidized bed reactor of this utility model. In the figure, 1 is the tank body, 1-1 is the water distribution device, 1-2 is the rectifier, 1-3 is the three-phase separator; 1-4 is the overflow weir; 1-5 is the water inlet; 1-6 is the reflux port; 1-7 is the drain port, 2 is the water inlet pump, and 3 is the reflux pump. Detailed Implementation
[0020] The beneficial effects of this utility model are verified using the following examples.
[0021] Example 1: The countercurrent anaerobic fluidized bed reactor of this example consists of a tank 1, an inlet pump 2, and a reflux pump 3. The tank 1 is a cylindrical body with a conical bottom. Inside the tank 1, a water distribution device 1-1 is installed in the middle section, a rectifier device 1-2 is installed in the lower section, and a three-phase separator 1-3 is installed in the upper section. The top of the tank 1 is open, and an overflow weir 1-4 and a drain outlet 1-7 are installed at the top. An inlet 1-5 is installed above the water distribution device 1-1 in the middle section of the side wall of the tank 1. The inlet pump 2 is connected to the inlet 1-5. A reflux outlet 1-6 is installed at the bottom of the tank 1, and the reflux outlet 1-6 is connected to the inlet 1-5 via the reflux pump 3.
[0022] The steps for treating domestic sewage using the countercurrent anaerobic fluidized bed reactor of Example 1 are as follows:
[0023] Anaerobic sludge from the secondary sedimentation tank is added to tank 1. After 24 hours of settling, the sludge layer height is one-third of the height of inlet 1-5. Domestic sewage with a temperature of 20℃, pH of 7, and COD concentration of 150-300 mg / L is fed into tank 1 via inlet pump 2. The sewage flows downward through distribution device 1-1, allowing the sludge to mix thoroughly in the lower part of the reaction zone and in the return pipe. The mixed liquor suspended solids concentration (MLSS) in the reaction zone is 5000 mg / L. The flow rate of return pump 3 is controlled to achieve a flow velocity of 5 m / h in the reaction zone. The return liquid (containing sludge) is returned to inlet 1-5 via return port 1-6 and return pump 3 to mix with fresh domestic sewage. Simultaneously, due to the presence of the inlet water, some water is squeezed upward and separated, and discharged through three-phase separator 1-3 and overflow weir 1-4. The hydraulic retention time (HRT) of the domestic sewage in tank 1 is 5 hours, and the total organic load is 1 kg COD·m³. -3 ·d -1 To complete the treatment of domestic sewage.
[0024] In Example 1, the COD of the treated wastewater was 38 mg / L, which met the discharge standards.
[0025] This invention relates to a counter-current anaerobic fluidized bed reactor, which improves upon both its operation and local structure. Firstly, the reflux direction is reversed. Traditional reactors have the inlet located at the bottom and the reflux outlet at the top sedimentation zone, while this reactor has the inlet in the reaction zone in the middle of the tank and the reflux outlet at the bottom. This counter-current method perfectly solves the sludge-water separation problem, achieving clear sludge-water stratification in the reaction zone. Maintaining a high reflux velocity ensures thorough mixing of the sludge in the reaction zone, achieving a final effluent COD of less than 50 mg / L with a shorter hydraulic retention time. Furthermore, this equipment operates at ambient temperature, requiring no heating system, and treats domestic or municipal wastewater using a completely anaerobic method to ensure COD compliance. By changing the reactor's operation, the mixing and separation effects in the reaction zone are enhanced, resolving the contradiction between mixing and separation in traditional reactors.
Claims
1. A countercurrent anaerobic fluidized bed reactor, characterized in that... The reactor includes: a tank (1), an inlet pump (2), and a return pump (3); The tank (1) is a cylindrical body with a conical bottom. Inside the tank (1), a water distribution device (1-1) is installed in the middle section, a rectifier device (1-2) is installed in the lower section, and a three-phase separator (1-3) is installed in the upper section. The top of the tank (1) is an opening, and an overflow weir (1-4) and a drain outlet (1-7) are installed at the top. An inlet (1-5) is provided above the water distribution device (1-1) in the middle section of the side wall of the tank (1); the water pump (2) is connected to the inlet (1-5); An outlet (1-6) is provided at the bottom of the tank (1), and the outlet (1-6) is connected to the inlet (1-5) via a reflux pump (3).
2. The countercurrent anaerobic fluidized bed reactor according to claim 1, characterized in that, The countercurrent anaerobic fluidized bed reactor also includes a screen for removing solid waste.
3. A countercurrent anaerobic fluidized bed reactor according to claim 1 or 2, characterized in that, The countercurrent anaerobic fluidized bed reactor also includes a temperature control system, with an insulation layer added to the outside of the tank (1).
4. A countercurrent anaerobic fluidized bed reactor according to claim 1 or 2, characterized in that, The countercurrent anaerobic fluidized bed reactor also includes a gas collection device, which is connected to a three-phase separator (1-3).