A biological-fenton-ozone synergistic wastewater treatment system

Abstract

The application provides a kind of biological-Fenton-ozone synergistic wastewater treatment system, belongs to industrial wastewater treatment field.The system includes the communication of adjusting pool, biochemical pool, first sedimentation tank, Fenton catalytic oxidation device, second sedimentation tank, ozone catalytic oxidation device and clean water pool in turn.The five-stage partition structure of anaerobic section to post aerobic section is used in biochemical pool, and each section is filled with specific microbial filler: anaerobic section enriches phosphorus-accumulating bacteria to degrade organic matter, front / back anoxic section prevents filler from hardening by stirrer and inoculates denitrifying bacteria to remove nitrogen, front / back aerobic section is oxygenated by aeration device and enriches nitrifying bacteria to achieve efficient nitrification.The sludge of first sedimentation tank is returned to anaerobic section of biochemical pool to reduce sludge production;after Fenton unit decomposes refractory organic matter, second sedimentation tank adds phosphorus removal agent to strengthen phosphorus removal;ozone unit deeply oxidizes residual pollutants and is equipped with backwashing device.The system significantly reduces reagent consumption and operating cost.

Description

Technical Field

[0001] This application relates to the field of water treatment technology, and in particular to a biological-Fenton-ozone synergistic wastewater treatment system. Background Technology

[0002] Currently, in the field of industrial wastewater treatment, such as pharmaceutical, coking, and dyeing wastewater, there are significant characteristics such as high pollutant concentration and complex composition, difficulty in biodegradation and ecotoxicity, and large fluctuations in water quality and quantity. Single treatment technologies are often unable to meet increasingly stringent emission standards (such as chemical oxygen demand COD < 50 mg / L and total nitrogen TN < 15 mg / L).

[0003] Chinese Patent, Publication No. CN216472414U, Publication Date: May 10, 2022, discloses "A Fenton-Ozone Combined Water Treatment System", including an inlet tank, a Fenton oxidation tower, an iron sludge aging tank, an ozone oxidation tower, and a sedimentation tank; the inlet tank is connected to the inlet of the Fenton oxidation tower, the Fenton oxidation tower is filled with iron shavings as a zero-valent iron source, the overflow outlet of the Fenton oxidation tower is connected to the iron sludge aging tank, the overflow outlet of the iron sludge aging tank is connected to the ozone oxidation tower, and the overflow outlet of the ozone oxidation tower is connected to the sedimentation tank.

[0004] The shortcoming of this technical solution is that although it integrates Fenton and ozone, it does not first utilize biological units to degrade easily pollutants, resulting in high consumption of oxidants. Utility Model Content

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a biological-Fenton-ozone synergistic wastewater treatment system, which first utilizes biological units to preferentially remove easily degradable organic matter, nitrogen, and phosphorus, thereby reducing the subsequent oxidation load and thus reducing the consumption of oxidants.

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

[0007] This application provides a biological-Fenton-ozone synergistic wastewater treatment system, comprising: an equalization tank, into which wastewater flows; a biological treatment tank, the outlet of which is connected to the inlet of the biological treatment tank; a first sedimentation tank, the outlet of which is connected to the inlet of the first sedimentation tank; a Fenton catalytic oxidation device, the outlet of which is connected to the inlet of the first sedimentation tank; a second sedimentation tank, the outlet of which is connected to the inlet of the second sedimentation tank; an ozone catalytic oxidation device, the outlet of which is connected to the inlet of the second sedimentation tank; and a clear water tank, the outlet of which is connected to the inlet of the clear water tank, the clear water tank being provided with an outlet.

[0008] As a preferred technical solution, the biological treatment tank includes an anaerobic section, a pre-anoxic section, a pre-aerobic section, a post-anoxic section, and a post-aerobic section arranged sequentially.

[0009] As a preferred technical solution, the anaerobic section is filled with microbial packing material containing at least one of the following microorganisms: fermenting bacteria, acid-producing bacteria, and polyphosphate-accumulating bacteria; the pre-anoxic section is filled with microbial packing material containing at least one of the following microorganisms: heterotrophic denitrifying bacteria, sulfur-autotrophic denitrifying bacteria, and denitrifying polyphosphate-accumulating bacteria; the pre-aerobic section is filled with microbial packing material containing at least one of the following microorganisms: ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, polyphosphate-accumulating bacteria, and aerobic denitrifying bacteria; the post-anoxic section is filled with microbial packing material containing at least one of the following microorganisms: denitrifying phosphorus-removing bacteria and facultative denitrifying bacteria; and the post-aerobic section is filled with microbial packing material containing at least one of the following microorganisms: highly efficient nitrifying bacteria, aerobic denitrifying bacteria, and organic matter-degrading bacteria.

[0010] As a preferred technical solution, the bottom of the first sedimentation tank is provided with a sludge outlet, the bottom of the anaerobic section is provided with a sludge inlet, the sludge outlet is connected to the sludge inlet through a sludge return pipe, and a sludge return pump is provided on the sludge return pipe.

[0011] As a preferred technical solution, the second sedimentation tank is connected to a phosphorus removal agent dosing device.

[0012] As a preferred technical solution, the ozone catalytic oxidation device is connected to a backwashing device.

[0013] As a preferred technical solution, packing supports are fixedly installed in the anaerobic section, the pre-anoxic section, the pre-aerobic section, the post-anoxic section, and the middle part of the post-aerobic section, and the packing supports support the microbial packing. A mixer is installed in the anaerobic section, the pre-anoxic section, and the post-anoxic section. The mixing shaft of the mixer is set vertically. A gap is left in the middle of the microbial packing in the anaerobic section, the pre-anoxic section, and the post-anoxic section for the mixing shaft to pass through. The mixing blades of the mixer are located below the microbial packing.

[0014] As a preferred technical solution, the biological tank is connected to an aeration device, which includes an air compressor, an aeration main pipe, and several aeration branch pipes. The air compressor is connected to the aeration main pipe, and the several aeration branch pipes are connected to the aeration main pipe. Each aeration branch pipe is equipped with a valve and at least one aeration head. At least one set of aeration branch pipes is provided at the lower part of the front aerobic section and the rear aerobic section.

[0015] Compared with the prior art, the beneficial effects of this application are as follows:

[0016] This application first utilizes biological units to preferentially remove easily degradable organic matter, nitrogen, and phosphorus, thereby reducing the subsequent oxidation load and thus reducing oxidant consumption. Through a streamlined process coupling of biochemical, Fenton, and ozone treatment, this application significantly reduces sludge production and operating costs while efficiently removing recalcitrant organic matter, nitrogen, and phosphorus, achieving the goal of low-carbon deep treatment of industrial wastewater. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the biological-Fenton-ozone synergistic wastewater treatment system of this application.

[0018] Figure 2 This is a schematic diagram of the connection structure of the biological-Fenton-ozone synergistic wastewater treatment system of this application;

[0019] Figure 3 This is a schematic diagram of the structure of the biochemical pool in this application;

[0020] Figure 4 for Figure 3 A sectional view of section AA in the middle;

[0021] Figure 5 for Figure 3 A sectional view of section BB in the middle;

[0022] Figure 6 for Figure 5 A sectional view of the CC section;

[0023] The structure includes: 1. Equalization tank; 1-1. Inlet of equalization tank; 1-2. Outlet of equalization tank; 2. Biological treatment tank; 2-1. Inlet of biological treatment tank; 2-2. Anaerobic section; 2-3. Pre-anoxic section; 2-4. Pre-aerobic section; 2-5. Post-anoxic section; 2-6. Post-aerobic section; 2-7. Sludge inlet; 2-9. Equipment room; 2-10. Water passage hole; 2-11. Packing support; 2-12. Mixer; 2-13. Connecting pipe one; 2-14. Connecting pipe two; 2-15. Discharge pipe; 2-16. Air compressor; 2-17. Main aeration pipe; 2-18. Aeration branch pipe; 2-19. Aeration head; 3. First sedimentation tank; 3-1. First... 3-1. Inlet of sedimentation tank; 3-2. Outlet of first sedimentation tank; 3-3. Sludge discharge end one; 3-4. Sludge discharge end; 4. Fenton catalytic oxidation device; 4-1. Inlet of Fenton catalytic oxidation device; 4-2. Outlet of Fenton catalytic oxidation device; 5. Second sedimentation tank; 5-1. Inlet of second sedimentation tank; 5-2. Outlet of second sedimentation tank; 5-3. Sludge discharge end two; 6. Ozone catalytic oxidation device; 6-1. Inlet of ozone catalytic oxidation device; 6-2. Outlet of ozone catalytic oxidation device; 7. Clear water tank; 7-1. Outlet; 8. Sludge return pump; 9. Sludge discharge pump two; 10. Lift pump; 11. Sludge discharge pump one. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present application, the technical solutions in specific embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0025] like Figure 1 and Figure 2 As shown, this application provides a biological-Fenton-ozone synergistic wastewater treatment system, which includes an equalization tank 1, a biochemical tank 2, a first sedimentation tank 3, a Fenton catalytic oxidation device 4, a second sedimentation tank 5, and a clear water tank 7 connected in sequence.

[0026] Wastewater is introduced into the inlet 1-1 of the equalization tank. A booster pump 10 is installed on the inlet pipe of the equalization tank 1.

[0027] Industrial wastewater discharge varies with production conditions, resulting in uneven water quality and unstable flow rates. This is especially true during production accidents or periods of heavy rainfall, when the wastewater quality and quantity fluctuate even more significantly. These changes can disrupt the wastewater treatment process, reduce treatment efficiency, and prevent the treatment equipment from reaching its designed capacity. To ensure the treatment process operates normally and is unaffected by peak flow rates or concentrations, the wastewater must have a relatively stable flow rate and uniform quality before treatment. Therefore, water quality and quantity equalization is necessary. The equalization tank 1 fulfills this requirement.

[0028] The equalization tank 1 mainly serves three functions: regulating water volume, balancing water quality, and pretreatment. Specific functions include: (1) providing a buffer against organic loads to prevent drastic changes in the biological treatment system; (2) controlling pH to reduce the amount of chemicals used in neutralization; (3) reducing flow fluctuations in the physicochemical treatment system to ensure the chemical addition rate is suitable for the feed equipment's capacity; (4) allowing continued wastewater input to the biological treatment system even when the plant is shut down; (5) controlling wastewater discharge to the municipal system to mitigate changes in wastewater load distribution; and (6) preventing high concentrations of toxic substances from entering the biological treatment system.

[0029] The outlet end 1-2 of the equalization tank is connected to the inlet end 2-1 of the biological treatment tank.

[0030] Specifically, the biological treatment tank 2 includes an anaerobic section 2-2, a pre-anoxic section 2-3, a pre-aerobic section 2-4, a post-anoxic section 2-5, and a post-aerobic section 2-6 arranged sequentially.

[0031] More specifically, the anaerobic section 2-2 is filled with microbial packing material containing at least one of the following microorganisms: fermenting bacteria, acid-producing bacteria, and polyphosphate-accumulating bacteria; the pre-anoxic section 2-3 is filled with microbial packing material containing at least one of the following microorganisms: heterotrophic denitrifying bacteria, sulfur-autotrophic denitrifying bacteria, and denitrifying polyphosphate-accumulating bacteria; the pre-aerobic section 2-4 is filled with microbial packing material containing at least one of the following microorganisms: ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, polyphosphate-accumulating bacteria, and aerobic denitrifying bacteria; the post-anoxic section 2-5 is filled with microbial packing material containing at least one of the following microorganisms: denitrifying phosphorus-removing bacteria and facultative denitrifying bacteria; and the post-aerobic section 2-6 is filled with microbial packing material containing at least one of the following microorganisms: highly efficient nitrifying bacteria, aerobic denitrifying bacteria, and organic matter-degrading bacteria.

[0032] Anaerobic stage 2-2 is used to hydrolyze large organic molecules (such as proteins and polysaccharides), releasing phosphorus and providing a readily degradable carbon source for subsequent denitrification and phosphorus removal. Fermenting bacteria, such as *Clostridium* and *Bacteroides*, break down complex organic matter into short-chain fatty acids (acetic acid, propionic acid). Acid-producing bacteria, such as *Acidobacteria*, further convert organic matter into volatile fatty acids (VFAs). Polyphosphate-accumulating bacteria (PAOs), such as *Candidatus Accumulibacter*, release phosphates and absorb VFAs under anaerobic conditions to synthesize polyhydroxyalkanoates (PHAs).

[0033] In the pre-anoxic stage 2-3, denitrification is performed using the influent carbon source to reduce nitrate load. Heterotrophic denitrifying bacteria, such as *Paracoccus* and *Pseudomonas*, use nitrate (NO3⁻) as an electron acceptor and the carbon source as an electron donor to produce N₂. Sulfoautotrophic denitrifying bacteria, such as *Thiobacillus*, use sulfur as an electron donor to remove nitrogen in the presence of sulfides. Denitrifying polyphosphate (DPB) bacteria: Some DPB bacteria simultaneously absorb phosphorus and denitrify under anoxic conditions.

[0034] The initial aerobic stage (sections 2-4) is used for efficient nitrification (ammonia nitrogen → nitrite → nitrate) and organic matter oxidation. Ammonia-oxidizing bacteria (AOB): such as *Nitrosomonas*, convert NH4⁺ to NO2⁻. Nitrite-oxidizing bacteria (NOB): such as *Nitrospira*, convert NO2⁻ to NO3⁻. Polyphosphate-accumulating bacteria (PAOs): absorb excess phosphorus under aerobic conditions. Aerobic denitrifying bacteria: such as *Alcaligenes*, can still denitrify even with sufficient dissolved oxygen.

[0035] Post-anoxic stages 2-5 are used for deep nitrogen removal and denitrification phosphorus removal. Denitrifying phosphorus-removing bacteria (DPB): such as Dechloromonas and Acidovorax, use nitrate as an electron acceptor to simultaneously absorb phosphorus. Facultative denitrifying bacteria: such as Flavobacterium, utilize internal carbon sources or endogenous carbon for nitrogen removal.

[0036] The aerobic stages 2-6 are used for residual organic matter degradation, deep nitrification of ammonia nitrogen, and phosphorus reabsorption. Highly efficient nitrifying bacteria, such as Nitrococcus, are adapted to low ammonia nitrogen environments. Aerobic denitrifying bacteria, such as Acinetobacter, further remove residual nitrate nitrogen.

[0037] The outlet of biological tank 2 is connected to the inlet of the first sedimentation tank 3-1.

[0038] In this application, the biological treatment tank 2 and the first sedimentation tank 3 are integrated into a rectangular tank body, which is divided into: five individual tank bodies corresponding to the anaerobic section 2-2, the pre-anoxic section 2-3, the pre-aerobic section 2-4, the post-anoxic section 2-5, and the post-aerobic section 2-6; the first sedimentation tank 3; and the equipment room 2-9. The total effective volume of the rectangular tank body is approximately 5 m3, and its dimensions are 3.3 × 2.25 × 1.5 m (length × width × height).

[0039] The inlet 2-1 of the biological treatment tank is located above the anaerobic section 2-2. A water passage hole 2-10 is provided at the bottom of the partition between the anaerobic section 2-2 and the pre-anoxic section 2-3. A water passage hole 2-10 is provided in the lower middle part of the partition between the pre-anoxic section 2-3 and the pre-aerobic section 2-4. The pre-aerobic section 2-4 and the post-anoxic section 2-5 are connected by a connecting pipe 2-13. A water passage hole 2-10 is provided at the bottom of the partition between the post-anoxic section 2-5 and the post-aerobic section 2-6. The bottom of the first sedimentation tank 3 is shaped like a frustoconical trough. The post-aerobic section 2-6 and the first sedimentation tank 3 are connected by a connecting pipe 2-14. The connecting pipe 2-14 is inverted L-shaped, and the connection port between the connecting pipe 2-14 and the post-aerobic section 2-6 is located in the upper middle part of the post-aerobic section 2-6. The bottom of the anaerobic section 2-2, the pre-anoxic section 2-3, the pre-aerobic section 2-4, the post-anoxic section 2-5, the post-aerobic section 2-6, and the first sedimentation tank 3 are all equipped with a drain pipe 2-15.

[0040] Furthermore, packing supports 2-11 are fixedly installed in the middle sections of anaerobic section 2-2, pre-anoxic section 2-3, pre-aerobic section 2-4, post-anoxic section 2-5, and post-aerobic section 2-6, respectively, supporting the microbial packing material. A mixer 2-12 is installed in each of the anaerobic section 2-2, pre-anoxic section 2-3, and post-anoxic section 2-5. The mixing shaft of the mixer 2-12 is vertically oriented, and a gap is left between the microbial packing material in the anaerobic section 2-2, pre-anoxic section 2-3, and post-anoxic section 2-5 for the mixing shaft to pass through. The mixing blades of the mixer 2-12 are located below the microbial packing material.

[0041] Furthermore, the biological treatment tank 2 is connected to an aeration device, which includes an air compressor 2-16, an aeration main pipe 2-17, and several aeration branch pipes 2-18. The air compressor 2-16 is connected to the aeration main pipe 2-17, and the several aeration branch pipes 2-18 are connected to the aeration main pipe 2-17. Each aeration branch pipe 2-18 is equipped with a valve and at least one aeration head 2-19. At least one set of aeration branch pipes 2-18 is provided at the lower part of the pre-aerobic section 2-4 and the post-aerobic section 2-6. The air compressor 2-16 is installed in the equipment room 2-9.

[0042] In this application, at least one set of aeration branch pipes 2-18 are also provided at the lower part of the anaerobic section 2-2, the pre-anoxic section 2-3, and the post-anoxic section 2-5. The anaerobic section 2-2 is equipped with aeration heads 2-19: when the influent COD is too high or the water quality fluctuates, the aeration rate can be adjusted to temporarily switch the anaerobic section 2-2 to anoxic state (DO 0.5~1.0 mg / L), utilizing denitrifying bacteria to degrade some organic matter and enhance the system's resistance to shock loads; micro-aeration can oxidize malodorous gases such as H2S produced in the anaerobic section 2-2, reducing corrosion risk and improving the operating environment. Aeration heads 2-19 are installed in the pre- and post-anoxic sections 2-5: Strict oxygen control (DO 0.2~0.5 mg / L) is required in the anoxic section, but micro-aeration can prevent local dead zones, ensuring uniform distribution of nitrate (NO3⁻) and carbon source, and avoiding incomplete denitrification. If the influent carbon source is insufficient, the post-anoxic section 2-5 is prone to depletion of internal carbon source, leading to a decrease in denitrification efficiency. Intermittent aeration can stimulate phosphorus release by polyphosphate-accumulating organisms (PAOs), and the released COD serves as a carbon source for denitrification, achieving "internal carbon source supplementation." Creating a gradient dissolved oxygen environment (e.g., DO 0.3~0.7 mg / L) in the anoxic section allows some aerobic denitrifying bacteria (e.g., Thaurea) to simultaneously degrade organic matter and nitrate under low oxygen conditions, improving denitrification efficiency.

[0043] The outlet 3-2 of the first sedimentation tank is connected to the inlet 4-1 of the Fenton catalytic oxidation device.

[0044] Furthermore, the bottom of the first sedimentation tank 3 is equipped with a sludge outlet 3-4, and the bottom of the anaerobic section 2-2 is equipped with a sludge inlet 2-7. The sludge outlet 3-4 is connected to the sludge inlet 2-7 through a sludge return pipe, and a sludge return pump 8 is installed on the sludge return pipe. Part of the sludge from the first sedimentation tank 3 is injected into the anaerobic section 2-2 through the sludge return pump 8 to provide polyphosphate-accumulating bacteria, promote the hydrolysis of organic matter and the release of phosphorus.

[0045] Fenton catalytic oxidation occurs under acidic or alkaline conditions when H₂O₂ generates hydroxyl groups with strong oxidizing power in the presence of Fe²⁺. The chain begins with the generation of •OH, while other reactive oxygen species and reaction intermediates form the chain nodes. The chain terminates when these reactive oxygen species are consumed. The reaction mechanism is relatively complex; these reactive oxygen species only supply organic molecules, mineralizing them into inorganic substances such as CO₂ and H₂O. Furthermore, the Fenton catalytic oxidation device 4 also breaks bonds in organophosphorus compounds that were not removed during the biochemical stage.

[0046] The outlet end 4-2 of the Fenton catalytic oxidation device is connected to the inlet end 5-1 of the second sedimentation tank.

[0047] In this application, the Fenton catalytic oxidation device 4 and the second sedimentation tank 5 are integrated, with a maximum processing capacity of 12 m3 / d and dimensions of 6 × 2.5 × 2 m (length × width × height).

[0048] Furthermore, the second sedimentation tank 5 is connected to a phosphorus removal agent dosing device. Adding an appropriate amount of phosphorus removal agent to the second sedimentation tank 5 can remove the broken-bond organic phosphorus from the Fenton catalytic oxidation device 4.

[0049] The bottom of the first sedimentation tank 3 is equipped with a sludge discharge end 3-3, through which the remaining sludge in the first sedimentation tank 3 is discharged. The bottom of the second sedimentation tank 5 is equipped with a sludge discharge end 5-3, through which the remaining sludge in the second sedimentation tank 5 is discharged. A sludge discharge pump 11 is installed on the sludge discharge pipeline of the first sedimentation tank 3, and a sludge discharge pump 9 is installed on the sludge discharge pipeline of the second sedimentation tank 5.

[0050] The outlet 5-2 of the second sedimentation tank is connected to the inlet 6-1 of the ozone catalytic oxidation device.

[0051] The ozone catalytic oxidation device 6 further removes pollutants that have not been fully oxidized in the wastewater, while also disinfecting and decolorizing the wastewater.

[0052] Furthermore, the ozone catalytic oxidation device 6 is connected to a backwashing device.

[0053] In this application, the ozone catalytic oxidation device 6 and the backwashing device are integrated, with a maximum processing capacity of 10 m3 / d and dimensions of 4×2×2m (length×width×height).

[0054] The water outlet 6-2 of the ozone catalytic oxidation device is connected to the water inlet of the water tank 7. The water tank 7 is equipped with an outlet 7-1.

[0055] The above-mentioned biological-Fenton-ozone synergistic wastewater treatment system operates as follows:

[0056] 1. Pump 10 lifts the wastewater to equalization tank 1, where it is treated in biological treatment tank 2, thus achieving preliminary treatment of the wastewater. The hydraulic retention time is 15-30 hours. Biological treatment tank 2 is used to remove easily degradable pollutants, some recalcitrant substances, and for nitrogen and phosphorus removal from the wastewater. A suitable biological treatment process can be selected based on the characteristics of the wastewater being treated. In this application, biological treatment tank 2 adopts a "multi-stage AAO process + packing material," wherein the total designed retention time for the anaerobic stage 2-2, the pre-anoxic stage 2-3, the pre-aerobic stage 2-4, the post-anoxic stage 2-5, and the post-aerobic stage 2-6 is 15-30 hours.

[0057] 2. The effluent from biological treatment tank 2 undergoes mud-water separation in the first sedimentation tank 3, with a hydraulic retention time of 2-6 hours.

[0058] 3. The supernatant in the first sedimentation tank 3 enters the Fenton catalytic oxidation device 4. Simultaneously, the reagents used for catalytic oxidation are pumped into the Fenton catalytic oxidation device 4 and mixed with the biochemically treated wastewater. This process degrades recalcitrant macromolecular pollutants into smaller molecules and mineralizes some of the pollutants. In this application, the reagent dosage in the Fenton catalytic oxidation device 4 is H2O2 / COD = 0.5-1.0 (mass ratio), and Fe2+ / H2O2 = 1:5. The Fenton catalytic oxidation device 4 removes recalcitrant organic matter through oxidation and breaks the bonds of organophosphorus compounds not removed in the biochemical stage.

[0059] 4. The effluent from the Fenton catalytic oxidation unit 4 undergoes mud-water separation in the second sedimentation tank 5, with a hydraulic retention time of 2-6 hours. Adding an appropriate amount of phosphorus removal agent to the second sedimentation tank 5 can remove the broken-bond organic phosphorus from the Fenton catalytic oxidation unit 4.

[0060] 5. The supernatant in the second sedimentation tank 5 enters the ozone catalytic oxidation device 6. Simultaneously, the reagents used for catalytic oxidation are also introduced into the ozone catalytic oxidation device 6 to further remove incompletely oxidized pollutants from the wastewater, while simultaneously disinfecting and decolorizing the wastewater. The O3 dosage in the ozone catalytic oxidation device 6 is 20-50 mg / L, and the contact time is 30-60 minutes.

[0061] The following is a specific application scenario of the above-mentioned biological-Fenton-ozone synergistic wastewater treatment system.

[0062] In this application scenario, in step 1, the hydraulic retention times for anaerobic stage 2-2, pre-anoxic stage 2-3, pre-aerobic stage 2-4, post-anoxic stage 2-5, and post-aerobic stage 2-6 are 2.4 h, 6.0 h, 10.6 h, 3 h, and 3 h, respectively; in step 5, the O3 dosage is 30 mg / L, and the contact time is 40 min. The effluent quality at different stages of the wastewater treatment system is shown in Table 1.

[0063] Table 1. Effluent quality at different stages of the wastewater treatment system

[0064]

[0065] Experimental results show that the concentrations of COD, NH4+-N, TP, and TN in the effluent of this application system are 35.52 mg / L, 2.86 mg / L, 2.86 mg / L, and 11.96 mg / L, respectively, meeting the Class A discharge standard, and the system is operating stably and well.

[0066] This application couples biochemical treatment, Fenton catalytic oxidation, and ozone catalytic oxidation into a chain system of "pretreatment-intermediate oxidation-deep mineralization," leveraging the synergistic advantages of multiple technologies to achieve stable and compliant wastewater discharge. The system's carbon emissions are lower than those of direct ozone advanced oxidation processes, achieving low-carbon wastewater treatment and holding significant importance for developing next-generation stable, efficient, and low-carbon industrial wastewater treatment processes.

[0067] It should be noted that the terms "first," "second," and similar terms used in this application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one," and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. "A plurality" or "several" indicates at least two. Unless otherwise stated, terms such as "front," "back," "left," "right," "lower," and / or "upper" are for illustrative purposes only and are not limited to a location or spatial orientation. Terms such as "comprising" or "including" indicate that the elements or objects preceding "comprising" encompass the elements or objects listed following "comprising" or "including" and their equivalents, and do not exclude 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.

[0068] The singular forms “a,” “the,” and “the” used in this application specification and appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0069] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A biological-Fenton-ozone synergistic wastewater treatment system, characterized in that, The biological-Fenton-ozone synergistic wastewater treatment system includes: The equalization tank is into which wastewater is introduced; A biological treatment tank, wherein the outlet of the regulating tank is connected to the inlet of the biological treatment tank; The first sedimentation tank, wherein the outlet of the biochemical tank is connected to the inlet of the first sedimentation tank; The Fenton catalytic oxidation device has its outlet connected to the inlet of the first sedimentation tank. The second sedimentation tank is connected to the inlet of the Fenton catalytic oxidation device. The ozone catalytic oxidation device has its outlet connected to the inlet of the second sedimentation tank. The clear water tank has an outlet connected to the inlet of the ozone catalytic oxidation device.

2. The biological-Fenton-ozone synergistic wastewater treatment system according to claim 1, characterized in that, The biochemical tank includes an anaerobic section, a pre-anoxic section, a pre-aerobic section, a post-anoxic section, and a post-aerobic section arranged sequentially.

3. The biological-Fenton-ozone synergistic wastewater treatment system according to claim 2, characterized in that, The anaerobic section is filled with microbial packing material containing at least one of the following microorganisms: fermenting bacteria, acid-producing bacteria, and polyphosphate-accumulating bacteria; The pre-anoxic section is filled with microbial packing material containing at least one of the following microorganisms: heterotrophic denitrifying bacteria, sulfur autotrophic denitrifying bacteria, and denitrifying polyphosphate-accumulating bacteria. The aerobic section is filled with a microbial packing material containing at least one of the following microorganisms: ammonia oxidizing bacteria, nitrite oxidizing bacteria, polyphosphate-accumulating bacteria, and aerobic denitrifying bacteria. The post-anoxic section is filled with microbial packing material containing at least one of the following microorganisms: denitrifying phosphorus-removing bacteria and facultative denitrifying bacteria. The aerobic section is filled with microbial packing material containing at least one of the following microorganisms: highly efficient nitrifying bacteria, aerobic denitrifying bacteria, and organic matter degrading bacteria.

4. The biological-Fenton-ozone synergistic wastewater treatment system according to claim 2, characterized in that, The bottom of the first sedimentation tank is provided with a sludge outlet, and the bottom of the anaerobic section is provided with a sludge inlet. The sludge outlet is connected to the sludge inlet through a sludge return pipe, and a sludge return pump is provided on the sludge return pipe.

5. The biological-Fenton-ozone synergistic wastewater treatment system according to claim 1, characterized in that, The second sedimentation tank is connected to a phosphorus removal agent dosing device.

6. The biological-Fenton-ozone synergistic wastewater treatment system according to claim 1, characterized in that, The ozone catalytic oxidation device is connected to a backwashing device.

7. The biological-Fenton-ozone synergistic wastewater treatment system according to claim 2, characterized in that, The anaerobic section, the pre-anoxic section, the pre-aerobic section, the post-anoxic section, and the middle part of the post-aerobic section are each fixedly equipped with a packing support, which supports the microbial packing material. Each of the anaerobic section, the pre-anoxic section, and the post-anoxic section is equipped with a mixer. The mixing shaft of the mixer is vertically arranged. A gap is left in the middle of the microbial packing material in the anaerobic section, the pre-anoxic section, and the post-anoxic section for the mixing shaft to pass through. The mixing blades of the mixer are located below the microbial packing material.

8. The biological-Fenton-ozone synergistic wastewater treatment system according to claim 2 or 7, characterized in that, The biological tank is connected to an aeration device, which includes an air compressor, an aeration main pipe, and several aeration branch pipes. The air compressor is connected to the aeration main pipe, and the several aeration branch pipes are connected to the aeration main pipe. Each aeration branch pipe is equipped with a valve and at least one aeration head. At least one set of the aeration branch pipes is provided at the lower part of the front aerobic section and the rear aerobic section.

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