Biodiesel wastewater treatment device coupled with internal and external circulation by quality-based pretreatment

Abstract

The application provides a biodiesel wastewater treatment device with separate quality pretreatment and internal and external circulation, which comprises a separate quality pretreatment module, an anaerobic reactor, a biochemical device and a catalytic oxidation device. The solution in the aerobic zone is refluxed to the anoxic zone by the action of a gas stripping device to form a first internal circulation. The solution in the aerobic zone is self-flowed to the sedimentation zone by the action of gas stripping, the bottom of the sedimentation zone is communicated with the anoxic zone, the sludge precipitated in the sedimentation zone flows into the anoxic zone to form a second internal circulation. The clear liquid at the outlet of the sedimentation zone is synchronously circulated to the water inlet of the anaerobic reactor to form an external circulation. The toxic and harmful substances are avoided from damaging and impacting the microorganisms, the metabolic activity of the microorganisms is maintained, the water quality is excellent, the system can realize high-load operation, and the over-load operation of the rear-end aerobic system is avoided.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and in particular to a biodiesel wastewater treatment device that combines fractional pretreatment with internal and external circulation. Background Technology

[0002] Biodiesel is a renewable fuel made from biomass resources (including animal and vegetable oils and waste oils). It can replace traditional diesel fuel to reduce dependence on fossil fuels and decrease net carbon emissions. Currently, biodiesel projects in my country mainly use waste cooking oil, gutter oil, and animal fats as raw materials. These raw materials are characterized by high levels of impurities, resulting in large volumes of wastewater and high pollutant concentrations during production. Typically, biodiesel wastewater has a pH as low as 2-4, COD concentrations reaching 30,000-90,000 mg / L, oil content exceeding 400 mg / L, and suspended solids concentrations exceeding 200 mg / L, making its disposal extremely difficult.

[0003] For example, Chinese patents CN201310597500.3, CN201410611046.7, CN201810153200.9, CN202110837022.3, and CN202210814407.2 disclose a biodiesel wastewater treatment process. The main process flow adopted is a combination of physicochemical and biological treatment methods. According to the treatment unit, it includes: homogenization and equalization adjustment, combination of oil separation and coagulation flotation tank, anaerobic biological technology, aerobic biological technology, and advanced oxidation technology. However, the above-mentioned processes generally suffer from the following problems: after homogenization of multiple wastewater streams, the concentrations of characteristic pollutants such as grease and heavy metals decrease, pretreatment efficiency drops significantly, and oil recovery is low; the concentrations of grease and colloidal substances entering the biological system remain high, affecting mass transfer and metabolic activity due to their adhesion to the surface of microorganisms, making it difficult for the COD removal rate of the anaerobic reactor to reach over 70%, and resulting in a high treatment load for the aerobic biological system; the quality of the biological effluent is poor, leading to large reagent consumption and high energy consumption in the downstream advanced treatment devices. The operating load of diesel wastewater treatment devices is difficult to increase, resulting in low treatment efficiency, large device size, and high investment costs.

[0004] Therefore, there is an urgent need for a new biodiesel wastewater treatment device. Utility Model Content

[0005] In view of this, the purpose of this disclosure is to propose a biodiesel wastewater treatment device with separate pretreatment and internal and external circulation to solve the problems of low treatment efficiency, poor effluent quality, low oil recovery and high energy consumption of existing biodiesel wastewater treatment systems.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] A biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation includes:

[0008] The system includes a pretreatment module, an anaerobic reactor, at least one biochemical device, and a catalytic oxidation device.

[0009] The biochemical device includes a shell, which contains an airlift device, an inlet zone, an anoxic zone, an aerobic zone, and a sedimentation zone, with the sedimentation zone located between the anoxic zone and the aerobic zone. The solution in the aerobic zone is recirculated back to the anoxic zone by the airlift device, forming a first internal circulation; and / or the solution in the aerobic zone is recirculated to the sedimentation zone by the airlift device. The bottom of the sedimentation zone is connected to the anoxic zone, and the sludge deposited in the sedimentation zone flows into the anoxic zone, forming a second internal circulation. The total internal circulation water volume is 2-45 times the inlet water volume of the anoxic zone.

[0010] The clear liquid from the outlet of the sedimentation zone is synchronously circulated to the inlet of the anaerobic reactor, forming an external circulation.

[0011] Furthermore, the fractional preprocessing module includes a first sub-processing module;

[0012] The first sub-processing module includes a gravity oil separator, a coagulation flotation tank, a hardening and heavy metal removal reaction tank, and a neutralization and recovery tank; wherein, the gravity oil separator has an inlet through which degumming wastewater is transported into the gravity oil separator; the outlet of the gravity oil separator is connected to the coagulation flotation tank via a pipeline;

[0013] The coagulation flotation tank has a first feeding port through which coagulant and alkali solution are added; the outlet of the coagulation flotation tank is connected to the hardness and heavy metal removal reaction tank via a pipeline.

[0014] The outlet of the hardness and heavy metal removal reaction tank is connected to the neutralization and recovery tank via a pipeline; the hardness and heavy metal removal reaction tank has a second feeding port, through which heavy metal removal liquid and alkali solution are added to the hardness and heavy metal removal reaction tank;

[0015] The outlet of the neutralization and recovery tank is connected to the anaerobic reactor via a pipeline; the neutralization and recovery tank has a third feeding port through which acid solution is added to the neutralization and recovery tank.

[0016] Furthermore, the fractional preprocessing module also includes a second sub-processing module and a third sub-processing module;

[0017] The second sub-processing module includes a washing water regulating tank; the washing water regulating tank has an inlet through which washing wastewater is transported into the washing water regulating tank;

[0018] The third sub-processing module includes a low-concentration equalization tank and a low-concentration air flotation device; the low-concentration equalization tank has an inlet through which low-concentration wastewater is transported into the low-concentration equalization tank.

[0019] The outlet of the low-concentration equalization tank is connected to the low-concentration flotation device via a pipeline; the low-concentration flotation device also has a dosing port through which mineral salts are added to the low-concentration flotation device; the outlet of the low-concentration flotation device is connected to the inlet of the biochemical device via a pipeline.

[0020] The outlet of the biochemical device is connected via a pipeline to the inlet of the catalytic oxidation device or the inlet of the anaerobic reactor.

[0021] The water treated by the catalytic oxidation device is piped to the discharge system.

[0022] Furthermore, the volume of the first internal circulation water is 2-40 times the volume of water entering the anoxic zone; the volume of sludge in the second internal circulation is 0.7-5.0 times the volume of water entering the anoxic zone.

[0023] Furthermore, the anaerobic reactor is used to convert macromolecular pollutants into small molecule pollutants and to convert some pollutants into methane for removal; the anaerobic reactor configuration is selected from upflow sludge blanket reactor, and / or completely mixed reactor, and / or baffle reactor.

[0024] Furthermore, the anaerobic reactor is equipped with a steam and / or hot water temperature control system, wherein the internal water temperature is maintained at 32-38°C.

[0025] Furthermore, the catalytic oxidation device is one or more combinations of ozone catalytic oxidation reactor, Fenton homogeneous catalytic oxidation reactor, Fenton heterogeneous catalytic oxidation reactor, and electrocatalytic oxidation reactor.

[0026] Furthermore, the outlets of the low-concentration flotation device, the anaerobic reactor, and the washing water regulating tank are connected and combined, and then transported to the biochemical device via pipeline.

[0027] Furthermore, the anoxic zone, the aerobic zone, and the precipitation zone of the biochemical device are integrated into a single configuration.

[0028] Furthermore, the air-lift device includes a first air-lift device and a second air-lift device;

[0029] An aeration device is provided at the bottom of the aerobic zone, and a degassing device is provided above it. The degassing device is connected to the second air-lifting device, and the second air-lifting device extends into the aerobic zone and is located above the aeration device.

[0030] The sedimentation zone is equipped with a reaction sedimentation device, the reaction sedimentation device is equipped with a water distributor, and the bottom side of the reaction sedimentation device is equipped with a reflux port.

[0031] A stirring device is installed in the anoxic zone. The stirring device is connected to a drive motor and rotates based on the drive motor to stir the water to be treated.

[0032] A first air-lift device is installed in the water inlet area, and the first air-lift device extends horizontally from the water inlet area to the anoxic area.

[0033] Compared with the prior art, this application has the following technical effects:

[0034] Separate pretreatment can significantly improve the removal efficiency of characteristic pollutants (especially oils, colloidal substances, and heavy metals) in degumming wastewater, reduce the toxic effects on microorganisms, and ensure the efficient and stable operation of the downstream biochemical system.

[0035] The high-frequency internal circulation within the biochemical device can avoid the toxic and harmful effects of substances on microorganisms, maintain their metabolic activity, ensure excellent effluent quality, and maintain a stable COD concentration of ≤200mg / L.

[0036] High-efficiency external circulation can further reduce the concentration of toxic and harmful substances entering the anaerobic reactor, ensuring that the COD removal rate in the anaerobic reactor exceeds 70%, ensuring that the system can operate at high load, and at the same time avoiding overload operation of the downstream aerobic system;

[0037] The excellent effluent quality further reduces the operating cost of the downstream catalytic oxidation reactor, saving energy and reagent consumption. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in this disclosure or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the functional modules of the wastewater treatment device according to an embodiment of this application;

[0040] Figure 2 This is a schematic diagram of the structure of the biochemical device according to an embodiment of this application;

[0041] Figure 3 This is a schematic diagram of the structure of the Fenton heterogeneous catalytic oxidation reactor according to an embodiment of this application;

[0042] The components are as follows: 1. Inlet pipe; 2. Anoxic zone; 3. Sedimentation zone; 3a. Reaction sedimentation device; 4. Aerobic zone; 4a. Aeration device; 5. First air-lift device; 6. Second air-lift device; 7. Outlet pipe; 8. Agitator; 9. Deaeration device; 10. Air pipe; 11. Water distributor; 20. Fenton heterogeneous catalytic oxidation reactor; 21. Inlet pump; 22. Return pump; 23. Ferrous iron dosing pump; 24. Hydrogen peroxide dosing pump; 25. Water distributor b; 26. Catalytic packing; 27. Return water tank; 28. Return pipe; 29. ​​Outlet tank. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0044] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this disclosure should have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar terms used in the embodiments of this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0045] This biodiesel wastewater treatment device, which employs a fractional pretreatment coupled with internal and external circulation, targets biodiesel wastewater and can effectively and efficiently remove characteristic pollutants such as grease, suspended flocs, colloidal substances, and heavy metals from degumming wastewater. This avoids the decrease in treatment efficiency caused by the reduction in the concentration of characteristic pollutants due to homogenization and dilution. At the same time, it also avoids interference and impact on the pretreatment process caused by other substances introduced during homogenization.

[0046] High-efficiency external circulation of treated water reduces the concentration of pollutants entering the anaerobic reactor, especially oils and greases. This prevents these substances from entraining microorganisms, affecting mass transfer and biological activity, and effectively ensuring the efficient operation of the anaerobic reactor, thereby improving its treatment efficiency and reducing the operational burden on downstream biological treatment units. High-efficiency internal circulation is employed in the aerobic zone, with the effluent significantly diluting the influent, minimizing toxicity to microorganisms and maintaining their metabolic activity. This allows for a higher treatment load, while the effluent quality is far superior to existing technologies, with the COD concentration consistently maintained below 200 mg / L, further reducing the operating costs of subsequent advanced treatment technologies.

[0047] This biodiesel wastewater treatment device, which combines pretreatment with internal and external circulation, has high treatment efficiency, good effluent quality, high oil recovery rate, low energy consumption, low reagent requirements, and a simple biodiesel wastewater treatment process.

[0048] The following description, in conjunction with the accompanying drawings, describes the biodiesel wastewater treatment device proposed in this application, which features a pretreatment process coupled with internal and external circulation.

[0049] like Figure 1 The diagram shown is a structural schematic of a biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation according to an embodiment of this application.

[0050] This biodiesel wastewater treatment device, which combines pretreatment with internal and external circulation, includes a pretreatment module, an anaerobic reactor, at least one biochemical unit 100, and a catalytic oxidation unit. The biochemical unit 100 includes a shell 110, which contains an air-lift device, an inlet zone, an anoxic zone 2, an aerobic zone 4, and a sedimentation zone 3, with the sedimentation zone 3 located between the anoxic zone 2 and the aerobic zone 4. The solution in the aerobic zone is self-recirculated to the anoxic zone by the air-lift device, forming a first internal circulation; and / or the solution in the aerobic zone is self-recirculated to the sedimentation zone by the air-lift device. The bottom of the sedimentation zone is connected to the anoxic zone, and the sludge settled in the sedimentation zone 3 flows into the anoxic zone 2, forming a second internal circulation. The total internal circulation volume is 2-45 times the inlet volume of the anoxic zone. The clear liquid from the sedimentation zone outlet is synchronously circulated to the inlet of the anaerobic reactor, forming an external circulation.

[0051] The high-efficiency internal circulation biochemical device used in this application avoids the toxic and harmful effects of substances on microorganisms, maintains their metabolic activity, and ensures excellent effluent quality with a stable COD concentration of ≤200mg / L. Simultaneously, the high-efficiency external circulation further reduces the concentration of toxic and harmful substances entering the anaerobic reactor, ensuring a COD removal rate exceeding 70% within the reactor, guaranteeing high-load operation of the system, and preventing overload operation of the downstream biochemical device.

[0052] Next, combine Figure 2The diagram illustrates the structure of the biochemical device in the biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation according to an embodiment of this application. The biochemical device 100 is configured as an integrated structure comprising an anoxic zone, an aerobic zone, and a sedimentation zone.

[0053] Specifically, the biochemical device 100 includes a shell 110, which contains an inlet zone 1, an anoxic zone 2, a sedimentation zone 3, and an aerobic zone 4. The sedimentation zone 3 is located between the anoxic zone 2 and the aerobic zone 4. The airlift device includes a first airlift device 5 and a second airlift device 6.

[0054] It should be noted that an aeration device 4a is provided at the bottom of the aerobic zone 4, and a degassing device 9 is provided above the aerobic zone 4. The degassing device 9 is connected to the second air-lifting device 6, and the second air-lifting device 6 extends to the aerobic zone 4 and is located above the aeration device 4a (in the y direction).

[0055] The sedimentation zone 3 is equipped with a reaction sedimentation device 3a, which contains a water distributor 11 and a reflux port 3a1 at its bottom.

[0056] The water inlet area is equipped with an inlet pipe 1 and a first air-lift device 5, which extends horizontally from the water inlet area to the anoxic zone 2. Preferably, the first air-lift device 5 extends horizontally (in the x direction) from the water inlet area to the anoxic zone 2 and is close to the return port 3a1.

[0057] A stirring device 8 is installed in the anoxic zone 2. The stirring device 8 is connected to a drive motor, and the rotation driven by the drive motor stirs the water to be treated. The first air-lift device 5, the second air-lift device 6, and the aeration device 4a are respectively connected to an air source (not shown in the figure) via corresponding air pipes 10. The water (meeting the standard) precipitated by the reaction sedimentation device 3a is discharged through the outlet pipe 7.

[0058] The integrated configuration of the anoxic zone 2, aerobic zone 4, and sedimentation zone 3 utilizes air lift to promote internal circulation of the sludge-water mixture within these zones. This dilutes toxic and harmful substances in the water, improving wastewater treatment efficiency and shock resistance. Specifically, the solution in aerobic zone 4 of the biochemical device 100 is self-recirculated back to anoxic zone 2 via the second air lift device 6, forming the first internal circulation. The solution in aerobic zone 4 of the biochemical device 100 is also self-recirculated back to sedimentation zone 3 via air lift. The bottom of sedimentation zone 3 is connected to anoxic zone 2, and the sludge settled in sedimentation zone 3 flows into anoxic zone 2, forming the second internal circulation. The total internal circulation water volume is 2-45 times the influent volume of the anoxic zone.

[0059] In a preferred embodiment, the volume of the first internal circulation water is 2-40 times the volume of the influent to the anoxic zone (preferably, such as 5, 10, 15, 20, 30, or 40 times). The volume of the second internal circulation sludge is 0.7-5.0 times the volume of the influent to the anoxic zone.

[0060] The high-frequency internal circulation within the biochemical device 100 in this application can avoid the toxic and harmful effects of substances on microorganisms, maintain the metabolic activity of microorganisms, ensure excellent effluent quality, and maintain a stable COD concentration of ≤200mg / L.

[0061] In this embodiment, the clarified liquid from the sedimentation zone outlet is synchronously circulated to the inlet of the anaerobic reactor, forming an external circulation. The high-efficiency external circulation adopted in this application can further reduce the concentration of toxic and harmful substances entering the anaerobic reactor, ensuring that the COD removal rate in the anaerobic reactor exceeds 70%, ensuring that the system can operate at high load, and at the same time avoiding overload operation of the downstream biochemical device.

[0062] The biodiesel wastewater treatment device with separate pretreatment and internal and external circulation in this embodiment includes a primary biochemical device (i.e., one biochemical device). In other embodiments, it may include multiple biochemical devices (such as two, three or more biochemical devices connected in series).

[0063] In this embodiment, the pretreatment module includes a first sub-processing module, a second sub-processing module, and a third sub-processing module. The first, second, and third sub-processing modules respectively refer to the process of classifying and collecting degumming wastewater, washing wastewater, and low-concentration wastewater, and then transporting them to corresponding devices for pretreatment.

[0064] The first sub-treatment module includes a gravity oil separator, a coagulation flotation tank, a hardening and heavy metal removal reaction tank, and a neutralization and recovery tank. The gravity oil separator has an inlet through which degumming wastewater is transported into the gravity oil separator. The outlet of the gravity oil separator is connected to the coagulation flotation tank via a pipeline.

[0065] The outlet of the coagulation flotation tank is connected to the hardness and heavy metal removal reaction tank via a pipeline. The coagulation flotation tank has a first feeding port through which coagulant and alkali solution are added; preferably, the first feeding port includes a first addition port and a second addition port, through which coagulant is added and alkali solution is added.

[0066] The outlet of the hardening and heavy metal removal reaction tank is connected to a neutralization and recovery tank via a pipeline. The hardening and heavy metal removal reaction tank has a second feeding port through which heavy metal removal solution and alkali solution are added. Preferably, the second feeding port includes a third feeding port and a fourth feeding port, through which heavy metal removal solution is added and alkali solution is added.

[0067] The outlet of the neutralization and setback tank is connected to the anaerobic reactor via a pipeline. The neutralization and setback tank has a third feed inlet through which acid solution is added.

[0068] The outlet of the anaerobic reactor is connected to the inlet pipe of the biochemical device via a pipeline. The outlet of the biochemical device is connected to the inlet of the catalytic oxidation device or the inlet of the anaerobic reactor via a pipeline. The water treated by the catalytic oxidation device is discharged to the discharge system via a pipeline.

[0069] When the first sub-treatment module is running, the degummed wastewater is sequentially transported to a gravity oil separator, a coagulation and flotation tank, a hardness and heavy metal removal reaction tank, and a neutralization and adjustment tank. Coagulants, heavy metal removal agents, and alkaline solutions are added to the tank to remove floating oil, emulsified oil, suspended solids, calcium ions, and metal ions from the water. After the reaction, acid is added to adjust the pH to neutral, and the solution is then transported to an anaerobic reactor for further treatment.

[0070] The second sub-treatment module includes a washing water equalization tank; the washing water equalization tank has an inlet through which washing wastewater is transported into the washing water equalization tank. The outlet of the washing water equalization tank is connected to the inlet pipe of the biological treatment unit via a pipeline, and the outlet of the biological treatment unit is connected to the inlet of the catalytic oxidation unit or the inlet of the anaerobic reactor via a pipeline. The water treated by the catalytic oxidation unit is discharged to the discharge system via a pipeline.

[0071] During the operation of this second sub-treatment module, the washing wastewater is collected in the washing water equalization tank for homogenization and equalization, and then transported together with the effluent from the anaerobic reactor and the effluent from the low-concentration flotation tank to the inlet pipe of the biological treatment unit. The outlet of the biological treatment unit is connected to the inlet of the catalytic oxidation unit or the inlet of the anaerobic reactor via a pipeline, and the water treated by the catalytic oxidation unit is discharged to the discharge system via a pipeline.

[0072] The third sub-treatment module includes a low-concentration equalization tank and a low-concentration flotation device. The low-concentration equalization tank has an inlet through which low-concentration wastewater is transported into the tank. The outlet of the low-concentration equalization tank is connected to the low-concentration flotation device via a pipeline. The low-concentration flotation device also has a dosing port through which mineral salts are added. The outlet of the low-concentration flotation device is connected to the inlet pipe of the biological treatment unit via a pipeline. The outlet of the biological treatment unit is connected to the inlet of the catalytic oxidation unit or the inlet of the anaerobic reactor via a pipeline. The water treated by the catalytic oxidation unit is discharged to the discharge system via a pipeline.

[0073] During the operation of this third sub-treatment module, low-concentration wastewater is collected in a low-concentration equalization tank for homogenization and equalization, and then transported to a low-concentration flotation tank to remove oily substances from the water. Aluminum salts are added to the low-concentration flotation unit to destabilize pollutants, which are then carried to the water surface by microbubbles to form scum for removal. It should be noted that the effluent outlets of the low-concentration flotation unit, the anaerobic reactor, and the washing water equalization tank are connected and combined, and transported via pipeline to the inlet pipe of the biological treatment unit. That is, the reacted solution, along with the effluent from the anaerobic reactor and the washing wastewater, enters the inlet pipe of the biological treatment unit. The effluent outlet of the biological treatment unit is connected via pipeline to the inlet of the catalytic oxidation unit or the anaerobic reactor; the water treated by the catalytic oxidation unit is then piped to the discharge system.

[0074] This biodiesel wastewater treatment unit, employing a fractional pretreatment coupled with internal and external circulation, targets and efficiently removes characteristic pollutants (oils, suspended flocs, colloidal substances, heavy metals, etc.) from degumming wastewater. This avoids the decrease in treatment efficiency caused by reduced concentrations of characteristic pollutants due to homogenization and dilution. Simultaneously, it avoids interference and impact from other substances introduced during homogenization on the pretreatment process. This significantly improves the removal efficiency of oils and colloidal substances, reduces the impact on subsequent anaerobic reactors and biological treatment units, and ensures the efficient operation of the biological system.

[0075] In this embodiment, the anaerobic reactor is used to convert large molecular pollutants into small molecular pollutants and to convert some pollutants into methane for removal. Preferably, the anaerobic reactor is configured as an upflow sludge bed reactor, and / or a completely mixed reactor, and / or a baffle reactor. More preferably, the anaerobic reactor can be equipped with internal wastewater recirculation and / or external effluent recirculation, with the recirculated liquid used to dilute toxic substances in the influent and form a good sludge-water mixture. Preferably, the ratio of circulating clear liquid in the sedimentation zone of the biological treatment unit to degumming wastewater is ≥2; more preferably, the ratio is ≥3. Preferably, the anaerobic reactor is equipped with a steam and / or hot water temperature control system, with the internal water temperature maintained at 32-38℃. Preferably, the outlet of the low-concentration flotation device is connected to the outlet of the anaerobic reactor and the outlet of the washing water equalization tank, and merges into the inlet pipe of the biological treatment unit with high-multiplication internal and external circulation.

[0076] In this embodiment, the catalytic oxidation device can be one or more combinations of ozone catalytic oxidation reactor, Fenton homogeneous catalytic oxidation reactor, Fenton heterogeneous catalytic oxidation reactor, and electrocatalytic oxidation reactor, used to perform advanced treatment on the effluent from the biological treatment device, ensuring that the COD concentration of the effluent is stably maintained at ≤50mg / L, and can meet the discharge standards.

[0077] Preferably, the catalytic oxidation device employs multi-point distributed ozone dosing along the water flow direction, with ≥5 ozone distribution points. This HiPOx ozone catalytic oxidation device has an internal plug-flow configuration for advanced treatment of the effluent from the biological treatment unit, ensuring a stable COD concentration of ≤50mg / L for compliant discharge.

[0078] This wastewater treatment device employs a fractional pretreatment approach for multiple wastewater streams, effectively and efficiently removing characteristic pollutants (such as aluminates, formaldehyde, waxy polytetrahydrofuran, and suspended particles) from the water. This avoids the decrease in treatment efficiency caused by homogenization and dilution leading to reduced concentrations of these pollutants. Simultaneously, it avoids interference and impact from other substances introduced during homogenization on the pretreatment process. It more effectively removes toxic substances from the water, reducing the toxic impact on subsequent anaerobic and aerobic biological systems and ensuring their efficient operation. Furthermore, the fractional pretreatment system allows for the separate collection of high-concentration pretreated wastewater, thereby improving the treatment efficiency of the anaerobic reactor and achieving a higher treatment load compared to existing technologies, while reducing equipment investment. This pretreatment module specifically removes formaldehyde, reducing the biotoxicity of the wastewater. It overcomes the current limitation of BDO wastewater treatment methods, which cannot remove formaldehyde and other toxic and harmful substances.

[0079] Preferably, the ozone catalytic oxidation reactor (HiPOx) employs multi-point distributed ozone dosing along the water flow direction, with the number of ozone distribution points being ≥5.

[0080] The HiPOx ozone catalytic oxidation reactor has a plug-flow configuration and is used to perform advanced treatment on the effluent from the biological treatment unit, ensuring that the COD concentration of the effluent is stably maintained at ≤50mg / L, so that it can be discharged in compliance with standards or transported to the reclaimed water system.

[0081] Optionally, the oxidation catalytic device is a Fenton heterogeneous catalytic oxidation reactor 20, such as... Figure 3As shown, the Fenton heterogeneous catalytic oxidation reactor 20 includes an inlet pump 21, a reflux pump 22, a ferrous dosing pump 23, a hydrogen peroxide dosing pump 24, a water distributor 25, catalytic packing material 26, a reflux tank 27, a reflux pipe 28, and an outlet tank 29. The inlet pump 21 is used to transport the wastewater to be treated into the reactor, the ferrous dosing pump 33 is used to add ferrous ions into the reactor, and the hydrogen peroxide dosing pump 24 is used to add hydrogen peroxide into the reactor. The water distributor 25 is located in the lower part of the Fenton heterogeneous catalytic oxidation reactor 20 and is used to receive the wastewater transported by the inlet pump 31 and distribute it evenly. The catalytic packing 26 fills the area above the water distributor 25 in the reactor and is used to provide catalytic sites for the Fenton reaction. The reflux tank 27 is located on one side of the upper part of the reactor, and the outlet tank 29 is located on the other side of the upper part of the reactor. The reflux pipe 28 connects the reflux tank 27 and the reflux pump 22. The reflux pump 22 is used to draw the wastewater in the reactor and circulate it back through the reflux pipe 28 and the reflux tank 27. The wastewater treated by catalytic oxidation is discharged from the reactor through the outlet tank 29.

[0082] It should be noted that the above description describes some embodiments of this disclosure. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in a different order than that shown in the above embodiments and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0083] This disclosure is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation, characterized in that, include: The system includes a pretreatment module, an anaerobic reactor, at least one biochemical device, and a catalytic oxidation device. The biochemical device includes a shell, which contains an airlift device, an inlet zone, an anoxic zone, an aerobic zone, and a sedimentation zone, with the sedimentation zone located between the anoxic zone and the aerobic zone. The solution in the aerobic zone is recirculated back to the anoxic zone by the airlift device, forming a first internal circulation; and / or the solution in the aerobic zone is recirculated to the sedimentation zone by the airlift device. The bottom of the sedimentation zone is connected to the anoxic zone, and the sludge deposited in the sedimentation zone flows into the anoxic zone, forming a second internal circulation. The total internal circulation water volume is 2-45 times the inlet water volume of the anoxic zone. The clear liquid from the outlet of the sedimentation zone is synchronously circulated to the inlet of the anaerobic reactor, forming an external circulation.

2. The biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation according to claim 1, characterized in that, The fractional preprocessing module includes a first subprocessing module; The first sub-processing module includes a gravity oil separator, a coagulation flotation tank, a hardening and heavy metal removal reaction tank, and a neutralization and recovery tank; wherein, the gravity oil separator has an inlet through which degumming wastewater is transported into the gravity oil separator; the outlet of the gravity oil separator is connected to the coagulation flotation tank via a pipeline; The coagulation flotation tank has a first feeding port through which coagulant and alkali solution are added; the outlet of the coagulation flotation tank is connected to the hardness and heavy metal removal reaction tank via a pipeline. The outlet of the hardness and heavy metal removal reaction tank is connected to the neutralization and recovery tank via a pipeline; the hardness and heavy metal removal reaction tank has a second feeding port, through which heavy metal removal liquid and alkali solution are added to the hardness and heavy metal removal reaction tank; The outlet of the neutralization and recovery tank is connected to the anaerobic reactor via a pipeline; the neutralization and recovery tank has a third feeding port through which acid solution is added to the neutralization and recovery tank.

3. The biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation according to claim 1, characterized in that, The fractional preprocessing module further includes a second sub-processing module and a third sub-processing module; The second sub-processing module includes a washing water regulating tank; the washing water regulating tank has an inlet through which washing wastewater is transported into the washing water regulating tank; The third sub-processing module includes a low-concentration equalization tank and a low-concentration air flotation device; the low-concentration equalization tank has an inlet through which low-concentration wastewater is transported into the low-concentration equalization tank. The outlet of the low-concentration equalization tank is connected to the low-concentration flotation device via a pipeline; the low-concentration flotation device also has a dosing port through which mineral salts are added to the low-concentration flotation device; the outlet of the low-concentration flotation device is connected to the inlet of the biochemical device via a pipeline. The outlet of the biochemical device is connected via a pipeline to the inlet of the catalytic oxidation device or the inlet of the anaerobic reactor. The water treated by the catalytic oxidation device is discharged into the discharge system via pipeline.

4. The biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation according to claim 1, characterized in that, The first internal circulation water volume is 2-40 times the influent volume of the anoxic zone; the second internal circulation sludge volume is 0.7-5.0 times the influent volume of the anoxic zone.

5. The biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation according to claim 1, characterized in that, The anaerobic reactor is used to convert macromolecular pollutants into small molecule pollutants and to convert some pollutants into methane for removal; the anaerobic reactor configuration is selected from upflow sludge blanket reactor, and / or completely mixed reactor, and / or baffle reactor.

6. The biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation as described in claim 1, characterized in that, The anaerobic reactor is equipped with a steam and / or hot water temperature control system, and the internal water temperature is maintained at 32-38℃.

7. The biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation as described in claim 1, characterized in that, The catalytic oxidation device is one or more combinations of ozone catalytic oxidation reactor, Fenton homogeneous catalytic oxidation reactor, Fenton heterogeneous catalytic oxidation reactor, and electrocatalytic oxidation reactor.

8. The biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation as described in claim 1, characterized in that, The outlets of the low-concentration flotation device, the anaerobic reactor, and the washing water regulating tank are connected and combined, and then transported to the biochemical device via pipeline.

9. The biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation as described in claim 1, characterized in that, The anoxic zone, aerobic zone, and precipitation zone of the biochemical device are integrated into one unit.

10. The biodiesel wastewater treatment device with separate pretreatment and coupled internal and external circulation as described in claim 1, characterized in that, The air-lift device includes a first air-lift device and a second air-lift device; An aeration device is provided at the bottom of the aerobic zone, and a degassing device is provided above it. The degassing device is connected to the second air-lifting device, and the second air-lifting device extends into the aerobic zone and is located above the aeration device. The sedimentation zone is equipped with a reaction sedimentation device, which contains a water distributor, and a reflux port is located at the bottom of the reaction sedimentation device. A stirring device is installed in the anoxic zone. The stirring device is connected to a drive motor and rotates based on the drive motor to stir the water to be treated. A first air-lift device is installed in the water inlet area, and the first air-lift device extends horizontally from the water inlet area to the anoxic area.

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