High-formaldehyde BDO wastewater treatment device

Abstract

The utility model discloses a high-formaldehyde BDO wastewater treatment device which comprises a pretreatment unit, an adjusting tank is arranged on one side of the treatment unit, the water outlet end of the adjusting tank is connected with a hydrolysis acidification tank, the water outlet end of the hydrolysis acidification tank is connected with an anaerobic-aerobic unit, and the water outlet end of the anaerobic-aerobic unit is connected with a secondary sedimentation tank; the anaerobic-aerobic unit comprises an anaerobic tank, a water outlet pipe of the anaerobic tank is connected with an auxiliary tank, a water outlet pipe of the auxiliary tank is connected with an aerobic tank, a first return pipe is arranged on the water outlet pipe of the anaerobic tank and connected to the water inlet end of the anaerobic tank, and a water outlet pipe of the aerobic tank is connected to the secondary sedimentation tank. The device is low in pretreatment process cost, non-toxic, simple in overall structure, easy to operate, higher in safety, shorter in anaerobic stage retention time, higher in impact resistance, more stable in system operation, small in occupied area and lower in building cost, and large-proportion backflow is designed.

Description

Technical Field

[0001] The utility model relates to the field of wastewater treatment devices, in particular to a high-formaldehyde BDO wastewater treatment device. Background Art

[0002] BDO wastewater is a highly viscous, high-boiling-point, salty organic wastewater generated during the production of 1,4-butanediol (BDO). 1,4-Butanediol, also known as BDO, is a widely used fine chemical raw material. Since its introduction to China from the United States in the early 21st century, its annual production has rapidly increased from tens of thousands of tons to millions of tons. The BDO production process generates a large amount of highly concentrated organic wastewater containing 1,4-butanediol, BuOH (butanol), methanol, propanol, propargyl alcohol, butynediol, water, and sodium salts (sodium formate, sodium hydroxide). Under given compositional conditions, this BDO organic wastewater tends to form a two-phase, low-boiling-point azeotropic mixture, making it difficult to separate the components of the azeotrope in a distillation column. In recent years, with the rapid development of 1,4-butanediol and other products, the treatment of this wastewater byproduct has become a pressing challenge.

[0003] Existing technologies mostly rely on incineration, which not only pollutes the atmosphere but also wastes resources, costing approximately 2,000-5,000 yuan per ton of organic wastewater. Biochemical treatment, however, costs only one thousandth of incineration. Therefore, biochemical treatment using highly efficient, salt-tolerant bacteria will likely become the primary treatment process for new BDO wastewater treatment projects in my country in the foreseeable future.

[0004] The commonly used biochemical process for treating BDO wastewater is the UASB + aerobic combined process. However, this process still has the problem of not being able to consistently meet the standards for treating BDO wastewater. The main reasons are: (1) Most of the organic matter in the wastewater is difficult to degrade completely; (2) The production wastewater contains formaldehyde, which will have a significant impact on the microbial system; (3) The production wastewater has a high salt content, making it difficult to cultivate microorganisms and the degradation effect is not ideal. To address the above reasons, the commonly used method is to add a pretreatment process before. The commonly used pretreatment process is the sodium hypochlorite method to remove formaldehyde. It involves adding hypochlorous acid at room temperature. Hypochlorous acid is a strong oxidant, and formaldehyde is an aldehyde organic matter. The reaction between them can lead to the occurrence of redox reactions.

[0005] This demonstrates the shortcomings of the existing process: It uses large amounts of hypochlorous acid, which is irritating, corrosive, oxidizing, and toxic. Long-term exposure to hypochlorous acid can have adverse effects on the human body, such as respiratory and digestive system diseases. Pretreatment with hypochlorous acid requires large amounts of treatment, resulting in high costs. The combined UASB and aerobic process also requires long residence times, resulting in high costs and significant resource waste. UASB uses granular sludge, which has a long culture cycle, requires high substrate concentrations, is prone to disintegration, requires high upwelling velocity, and is prone to sludge run-off in the equipment, resulting in high effluent SS and incomplete organic matter decomposition. This long-term trend can lead to a decrease in anaerobic tank sludge concentration, substandard effluent, increased VFA levels, acidification of the anaerobic tank, and complete breakdown of the biochemical system. In this case, the anaerobic system must be re-introduced, but granular sludge is expensive and requires a long culture cycle, often resulting in significant resource waste. Utility Model Content

[0006] The technical problem to be solved by the utility model is to provide a high-formaldehyde BDO wastewater treatment device, which has low pretreatment process cost and is non-toxic. At the same time, the overall structure is simple, easy to operate, and safer. The anaerobic stage residence time is shorter and a large proportion of reflux is designed, which has strong impact resistance, more stable system operation, small footprint, and lower construction cost.

[0007] In order to solve the above technical problems, the present invention provides a high-formaldehyde BDO wastewater treatment device, comprising a pretreatment unit, a regulating tank provided on one side of the treatment unit, the water outlet of the regulating tank being connected to a hydrolysis and acidification tank, the water outlet of the hydrolysis and acidification tank being connected to an anaerobic aerobic unit, the water outlet of the anaerobic aerobic unit being connected to a secondary sedimentation tank; the anaerobic aerobic unit comprising an anaerobic tank, the water outlet pipe of the anaerobic tank being connected to an auxiliary tank, the water outlet pipe of the auxiliary tank being connected to an aerobic tank, the water outlet pipe of the anaerobic tank being provided with a first reflux pipe connected to the water inlet of the anaerobic tank, and the water outlet pipe of the aerobic tank being connected to the secondary sedimentation tank.

[0008] Furthermore, the pretreatment unit includes a reactor, an inlet pipe is provided on one side of the reactor, an overflow port is provided on the reactor, a sedimentation tank is provided on one side of the overflow port, and the sedimentation tank is connected to the regulating tank.

[0009] Furthermore, the reactor is provided with a stirring device.

[0010] Furthermore, calcium hydroxide is added into the reactor.

[0011] Furthermore, a third return pipe is provided on the outlet pipe of the secondary sedimentation tank and is connected to the anaerobic tank.

[0012] Furthermore, a second return pipe is provided on the outlet pipe of the aerobic tank and connected to the auxiliary tank.

[0013] The beneficial effects of the utility model are: 1. The process is simple, easy to operate and safer.

[0014] 2. Pretreatment agents are more common and easier to purchase.

[0015] 3. The cost of pretreatment agents is lower and the operating costs are greatly reduced.

[0016] 4. The sugars converted in the pretreatment process have no toxic effect on microorganisms and are conducive to their growth, which is very beneficial for subsequent biological treatment.

[0017] 5. The anaerobic stage residence time is shorter, only 1 / 3 of the traditional process. It occupies a small area and has lower construction costs.

[0018] 6. A large proportion of reflux is designed in the anaerobic stage, which has strong impact resistance and makes the system operation more stable.

[0019] 7. The pretreatment reaction speed is fast and the cost is low; the formaldehyde removal rate in the pretreatment stage reaches 98%, which greatly reduces the difficulty of treatment in the biochemical stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0021] Explanation of the numbers in the figure: 1. Reactor; 2. Equalization tank; 3. Hydrolysis and acidification tank; 4. Anaerobic tank; 5. Auxiliary tank; 6. Aerobic tank; 7. Secondary sedimentation tank; 8. First return pipe; 9. Stirring device; 10. Second return pipe; 11. Third return pipe; 12. Sedimentation tank. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present invention.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this utility model, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0025] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0026] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0027] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0028] Reference Figure 1As shown, an embodiment of a high-formaldehyde BDO wastewater treatment device of the present invention includes a pretreatment unit, a regulating tank 2 is provided on one side of the treatment unit, the outlet end of the regulating tank 2 is connected to the hydrolysis and acidification tank 3, the outlet end of the hydrolysis and acidification tank 3 is connected to the anaerobic aerobic unit, and the outlet end of the anaerobic aerobic unit is connected to the secondary sedimentation tank 7; the anaerobic aerobic unit includes an anaerobic tank 4, the outlet pipe of the anaerobic tank 4 is connected to the auxiliary tank 5, the outlet pipe of the auxiliary tank 5 is connected to the aerobic tank 6, the outlet pipe of the anaerobic tank 4 is provided with a first return pipe 8 connected to the water inlet end of the anaerobic tank 4, and the outlet pipe of the aerobic tank 6 is connected to the secondary sedimentation tank 7.

[0029] The pretreatment unit includes a reactor 1, an inlet pipe is provided on one side of the reactor 1, an overflow port is provided on the reactor 1, a sedimentation tank 12 is provided on one side of the overflow port, and the sedimentation tank 12 is connected to the regulating tank 2; a stirring device 9 is provided on the reactor 1, and calcium hydroxide is added to the reactor 1; a second return pipe 10 is provided on the outlet pipe of the aerobic tank 6 and is connected to the auxiliary tank 5; a third return pipe 11 is provided on the outlet pipe of the secondary sedimentation tank 7 and is connected to the anaerobic tank 4.

[0030] Based on the anaerobic stage, this device adopts a process flow consisting of pretreatment, sewage conditioning tank 2, hydrolysis and acidification tank 3, anaerobic tank 4, aerobic tank 6, secondary sedimentation tank 7, and external drainage tank. During the pretreatment stage, the influent is first temperature-controlled (60°C), calcium hydroxide (lime milk) is added, and stirring is continued in reactor 1 for 30 minutes. During the reaction, there is a noticeable color change, and when the color turns bright yellow, the reaction is essentially complete. The overflow then flows into sedimentation tank 12 for precipitation, and the supernatant is collected. The calcium hydroxide dosage and reaction time can be adjusted according to the amount of formaldehyde to be removed.

[0031] After pretreatment, industrial wastewater is mixed in a comprehensive regulating tank 2 and then pumped into a hydrolysis and acidification reactor 1 for preliminary hydrolysis and acidification. The wastewater is then pumped into an anaerobic reactor 1, where anaerobic fermentation significantly reduces the concentration of organic matter. The anaerobic effluent enters an aerobic biochemical system, where pollutants are degraded by controlling dissolved oxygen, pH, and sludge age. Internal recirculation and a large-scale external recirculation system are installed at the inlet of anaerobic reactor 1 to dilute the inlet water at a high flow rate, ensuring more stable system operation.

[0032] Specific benefits are as follows: 1. Traditional processes generally use hypochlorous acid to remove formaldehyde from BDO wastewater. However, hypochlorous acid is a hazardous chemical, with major hazards including irritation, corrosiveness, oxidizing properties, and toxicity. If it comes into contact with flammable or explosive materials, it can react violently and release large amounts of oxygen, potentially causing serious accidents. Furthermore, long-term exposure to hypochlorous acid can have adverse effects on the human body, including respiratory and digestive system diseases. This process uses calcium hydroxide instead of hypochlorous acid, which is safer and offers better and more convenient procurement channels.

[0033] 2. For the same type of BDO wastewater with the same formaldehyde concentration, the cost of adding calcium hydroxide is only 1 / 70 of that of adding hypochlorous acid, greatly reducing operating costs.

[0034] 3. Formaldehyde undergoes a resinification reaction when heated under alkaline conditions, with Ca(OH)2 being the most commonly used catalyst. In the presence of lime, formaldehyde polymerizes to form hexoses. The converted sugars are not toxic to microorganisms and actually promote their growth, making them highly beneficial for subsequent biological treatment.

[0035] 4. The anaerobic retention time of traditional equipment is 40-70 hours, which takes a long time to react and requires a high tank capacity. This device has an anaerobic retention time of only 24 hours, which greatly shortens the retention time, occupies a small area, and is less expensive.

[0036] 5. An integrated device is used to control the reaction in each area. It has a high effluent circulation ratio for the removal of large amounts of organic matter in wastewater. The concentration of toxic substances (such as formaldehyde) in the raw water can be diluted to a level that microorganisms can tolerate, thereby ensuring that the microorganisms in the reactor can grow well.

[0037] 6. The UASB used in the anaerobic stage of traditional plants requires high upflow rates for the granular sludge, which is prone to sludge disintegration and sludge leakage. Regular sludge replenishment is required, but the high cost and long cultivation cycle of granular sludge often result in significant resource waste. This plant utilizes flocculent sludge combined with the company's independently developed high-efficiency bacterial strain, eliminating the issues of sludge leakage and regular replenishment. Flocculent sludge also has a short cultivation cycle, low cost, minimal equipment requirements, and does not require high upflow rates.

[0038] The above-described embodiments are merely preferred embodiments for the purpose of fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

Claims

1. A high-formaldehyde BDO wastewater treatment device, characterized in that: The system comprises a pretreatment unit, wherein a regulating tank (2) is provided on one side of the pretreatment unit, the outlet end of the regulating tank (2) is connected to a hydrolysis acidification tank (3), the outlet end of the hydrolysis acidification tank (3) is connected to an anaerobic aerobic unit, and the outlet end of the anaerobic aerobic unit is connected to a secondary sedimentation tank (7); The anaerobic aerobic unit comprises an anaerobic tank (4), the outlet pipe of the anaerobic tank (4) is connected to an auxiliary tank (5), the outlet pipe of the auxiliary tank (5) is connected to an aerobic tank (6), a first return pipe (8) is provided on the outlet pipe of the anaerobic tank (4) and is connected to the water inlet end of the anaerobic tank (4), and the outlet pipe of the aerobic tank (6) is connected to the secondary sedimentation tank (7).

2. The high-formaldehyde BDO wastewater treatment device according to claim 1, characterized in that: The pretreatment unit comprises a reactor (1), an inlet pipe is provided on one side of the reactor (1), an overflow port is provided on the reactor (1), a sedimentation tank (12) is provided on one side of the overflow port, and the sedimentation tank (12) is connected to the regulating tank (2).

3. The high-formaldehyde BDO wastewater treatment device according to claim 2, characterized in that: The reactor (1) is provided with a stirring device (9).

4. The high-formaldehyde BDO wastewater treatment device according to claim 2, characterized in that: Calcium hydroxide is added into the reactor (1).

5. The high-formaldehyde BDO wastewater treatment device according to claim 1, characterized in that: A second return pipe (10) is provided on the outlet pipe of the aerobic pool (6) and is connected to the auxiliary pool (5).

6. The high-formaldehyde BDO wastewater treatment device according to claim 1, characterized in that: A third return pipe (11) is provided on the outlet pipe of the secondary sedimentation tank (7) and is connected to the anaerobic tank (4).

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