Self-filtration activated sludge bioreactor and water treatment method

Abstract

The present invention provides a self-filtration activated sludge bioreactor and a water treatment method, which belong to the technical field of sewage treatment equipment. The bioreactor comprises a rectangular tank body, an aeration system, a self-filtration system, activated sludge and lightweight filler in the tank body, and zero-valent iron powder. The tank body is divided into an anaerobic zone, an anoxic zone, an aerobic zone, and a self-filtration drainage zone by a partition along the water inlet direction. An aeration system is provided at the bottom of the aerobic zone, and a self-filtration drainage zone is provided at the rear end, wherein a sludge hopper and a sludge return pump are provided at the bottom. The wastewater is subjected to the alternating reaction of the anaerobic-anoxic-aerobic zone, the action of the light filler biofilm, and the action of the hydroxyl iron produced on the surface of the iron powder to achieve efficient denitrification and phosphorus removal. The self-filtration drainage zone has a plurality of drainage troughs and an inverted U-shaped suspended self-filtration material provided on the trough wall. The self-filtration drainage zone realizes autonomous and efficient mud-water separation, sludge concentration, and autonomous filtration and flow of clean water through capillary action and gravity action. The bioreactor has the advantages of low consumption, no membrane pollution, no need for water pumps, and excellent mud-water separation effect.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment equipment, and in particular to a self-filtration activated sludge bioreactor and a water treatment method. Background Art

[0002] Membrane bioreactors (MBRs) are widely used in the water treatment industry. Their membrane filtration achieves efficient sludge-water separation, resulting in excellent effluent quality, eliminating the need for secondary sedimentation tanks and reducing equipment investment. Activated sludge is separated by the membrane under external pressure, and clean water passes through the membrane and exits the system. Because the sludge is trapped, the sludge concentration is 3-5 times higher than that of traditional activated sludge. This high sludge concentration creates a low F / M ratio, promoting endogenous respiration and denitrification. This conserves carbon sources while reducing sludge yield, effectively addressing sludge discharge and disposal issues. However, MBRs have long been plagued by membrane fouling. This occurs primarily due to the convection of the wastewater mixture onto the membrane surface under external pressure. Due to the hydrophilic and hydrophobic properties of the membrane surface and its microscopic interfacial properties, various hydrophilic organic compounds and colloids interact with the membrane surface, generating electrostatic interactions, clogging the membrane pores and reducing membrane flux. MBRs also consume a high amount of energy, primarily due to the energy required to operate the membranes, as well as the large amounts of chemicals required for backwashing, cleaning, and replacing the reactors. How to develop a low-consumption, low-cost, and efficient activated sludge treatment process for mud-water separation is of great significance. Summary of the Invention

[0003] The object of the present invention is to provide a self-filtration activated sludge bioreactor and a water treatment method to solve at least one technical problem in the above-mentioned background technology.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] On the one hand, the present invention provides a self-filtration activated sludge bioreactor, comprising a rectangular tank body, an aeration system, a self-filtration system, activated sludge in the tank body, and lightweight fillers and zero-valent iron powder. The tank body is divided into an anaerobic zone, an anoxic zone, an aerobic zone, and a self-filtration drainage zone along the water inlet direction by partitions, in a baffle + plug flow design. An aeration system is provided at the bottom of the aerobic zone, and a self-filtration drainage zone is provided at the rear end of the aerobic zone. A sludge hopper and a sludge return pump are provided at the bottom of the drainage zone to return the sludge to the anaerobic zone. The drainage zone is further provided with a plurality of drainage troughs, each of which is provided with an inverted U-shaped self-filtration material on the wall, and a Y-shaped support layer is provided on the upper part of the drainage trough to control the water outlet height and turning angle of the self-filtration material. One end of the self-filtration material is immersed below the water surface, and the other end is suspended above the water trough. The wastewater first climbs upward through the inverted U-shaped turn through the capillary action and the steric exclusion effect, and then flows into the collection tank through the action of gravity. The sludge is intercepted by the self-filtration material due to the steric effect and the action of gravity. The volume ratio of the anaerobic zone to the anoxic zone to the aerobic zone in the tank is 1:1:1-1:1:5. The self-filtration material is a porous hydrophilic material, typically made of flexible hydrophilic materials such as pure cotton fabric, porous sponge, porous rayon cloth, and porous activated carbon felt. The thickness ranges from 0.2cm to 10cm, with an average pore size of 0.1μm to 100μm. The front portion of the self-filtration material consists of a matrix and nanomaterials, primarily metal oxide or carbon nanomaterials such as nano-iron oxide, nano-zinc oxide, nano-titanium dioxide, carbon nanotubes, and nano-graphene. The lightweight filler used in the tank is primarily made of HDPE (high-density polyethylene) or PVC (polyvinyl chloride). Its shape ranges from cylindrical to cubic, with a porosity of 30% to 80% and a hydrophilic angle of less than 60°. The zero-valent iron powder in the pool is mainly high-purity reduced iron powder and hydroxyl iron powder, with a particle size range of 0.5μm-500μm and a dosage of 0.1-1g / L.

[0006] In a second aspect, the present invention provides a method for treating wastewater using the self-filtration activated sludge bioreactor device, comprising:

[0007] (1) Efficient, autonomous, pump-free separation of mud-water mixture: After the wastewater undergoes alternating reactions in the anaerobic, anoxic, and aerobic zones, it is automatically filtered and separated from the mud and water in the drainage area, achieving efficient sludge enrichment. Under the combined effects of the material's own capillary action, gravity, and spatial exclusion effect, the mud-water mixture climbs vertically upward under the capillary action of the porous material's internal channels. After reaching an appropriate height, it passes through the Y-shaped support layer and then moves downward under the action of gravity, gradually merging into the water collection tank and being discharged as the final effluent. In addition, due to the different molecular weights of soluble organic matter, during the self-filtration process, especially along the length direction of the self-filtration (i.e., the direction of water flow), the self-filtration material can be regarded as a plug-flow porous adsorber. By virtue of its own adsorption effect, it also produces a plug-flow adsorption effect, further promoting the deep adsorption and retention of organic matter of different molecular weights. On the contrary, while water molecules climb vertically upward, the sludge is trapped by the pore structure of the porous material itself, resulting in a spatial exclusion effect. As part of the sludge is trapped, a sludge filter layer is further formed on the outside of the porous material. This filter layer further hinders the subsequent sludge from entering the interior of the porous material, thus forming a spontaneous dynamic membrane filtration system. More importantly, unlike traditional membrane filtration, in the self-filtration system, after receiving the exclusion effect, the sludge will spontaneously return to the sludge hopper under the action of gravity.

[0008] Therefore, the differential mass transfer of mud and water separation ("water above mud below") effectively promotes mud and water separation and resolves membrane fouling. Even when large suspended solids, hair, or foam are present in the wastewater, the self-filtration system maintains efficient mud and water separation, exhibits excellent resistance to water quality fluctuations, requires minimal influent pretreatment, and is highly adaptable to complex water conditions.

[0009] (2) The wastewater is subjected to the high sludge concentration in the anaerobic-anoxic-aerobic zone through the suspension + biofilm + zero-valent iron coupling system, achieving efficient organic matter removal while strengthening endogenous denitrification and simultaneous chemical phosphorus removal. Relying on the efficient retention of activated sludge in the self-filtration system in (1) within the tank body, and the further increase of sludge volume within the lightweight filler, the sludge concentration can reach 5g / L-15g / L. The wastewater is thoroughly mixed with the return sludge in the anaerobic zone, effectively promoting the growth of dominant bacterial communities. Anaerobic phosphorus uptake and partial denitrification occur in the anaerobic zone. Denitrification is further enhanced after the wastewater enters the anoxic zone. Due to the high sludge concentration and limited oxygen mass transfer within the lightweight filler, simultaneous homogeneous and heterogeneous endogenous denitrification occurs, achieving efficient nitrogen removal without the need for an external carbon source, reducing sludge discharge intensity and subsequent sludge treatment issues. When the wastewater enters the aerobic zone, organic matter is efficiently oxidized to CO2 by the high-concentration sludge and lightweight filler biofilm, producing proliferating sludge. Simultaneously, phosphate is excessively released by phosphate-accumulating bacteria under aerobic conditions. It is fully adsorbed by the hydroxyl iron produced on the surface of the zero-valent iron powder to produce iron phosphate precipitation, further promoting sludge precipitation. The zero-valent iron core is encapsulated by the sludge, increasing the sludge specific gravity and enhancing sludge settling performance. This further promotes self-filtration mud-water separation and encourages the sludge to quickly fall off the surface of the self-filtration material and return to the sludge hopper. By loading nanomaterials on the front of the self-filtration material, nanomaterials can be used to promote the degradation of activated sludge, improve sludge flocculation and enhance sludge sedimentation performance, thereby achieving the degradation of organic pollutants in wastewater and efficient enrichment of activated sludge.

[0010] The beneficial effects of the present invention are: reducing the risk of wastewater short-circuiting, and at the same time, the plug flow reactor can effectively promote the chemical potential of organic matter oxidation in the wastewater, promote the formation of dominant strains of microorganisms in different environments, and use lightweight fillers to strengthen the biofilm system and suspended activated sludge to construct a composite microbial community and ecology, providing a dominant colony structure for denitrification and phosphorus removal; the development of the self-filtration system eliminates the membrane material in the traditional membrane bioreactor, and uses cheap and simple porous flexible materials as water-guiding materials to achieve pumpless filtration of wastewater, greatly reducing the energy consumption of water pumps in the traditional membrane filtration process; the reverse mass transfer characteristics of mud and water make it possible that even at a high sludge concentration, the retained sludge will not affect the flow of clean water, and will leave the self-filtration system by gravity, thereby realizing the autonomous separation of sludge and wastewater; by loading nanomaterials on the front of the self-filtration material, the nanomaterials are used to promote the degradation of activated sludge, improve the sludge flocculation and enhance the sludge sedimentation performance, thereby realizing the degradation of organic pollutants in the wastewater and the efficient enrichment of activated sludge. Different materials and materials can be selected according to different scenarios, such as sponges, fabrics, waste fabrics and other cheap materials for self-filtration systems, which greatly reduces costs while realizing waste resource utilization; the self-filtration system has strong pollution resistance potential, realizes autonomous separation and autonomous pollution resistance, is highly resistant to water quality fluctuations, has low pretreatment requirements, and has strong applicability and stability; it realizes sludge concentration and sludge concentration improvement, and realizes that the sludge enters the nutrient level at a low F / M, so that the sludge is in the endogenous denitrification stage. It not only has the advantages of low sludge yield and no need for external carbon source, but also has the performance of energy saving, low consumption, and pump-free operation, providing new ideas for the development of sustainable biochemical wastewater treatment technology.

[0011] Additional aspects and advantages of the present invention will be set forth in part in the following description, will become apparent from the following description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0013] Figure 1 This is a structural schematic diagram of a wastewater treatment device of a self-filtration activated sludge bioreactor according to an embodiment of the present invention.

[0014] Figure 2 This is a cross-sectional structural diagram of the self-filtration activated sludge bioreactor described in an embodiment of the present invention.

[0015] Figure 3This is a working principle diagram of the self-filtration drainage area of the self-filtration activated sludge bioreactor described in an embodiment of the present invention.

[0016] Among them: 1-tank body; 2-aeration system; 3-self-filtration system; 4-activated sludge; 5-lightweight filler; 6-partition; 7-anaerobic zone; 8-anoxic zone; 9-aerobic zone; 10-self-filtration drainage zone; 11-sludge hopper; 12-sludge return pump; 13-Y-type support layer; 14-collection tank. DETAILED DESCRIPTION

[0017] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention and are not to be construed as limiting the present invention.

[0018] Those skilled in the art will understand that unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs.

[0019] It should also be understood that terms, such as those defined in commonly used dictionaries, should be understood to have a meaning consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless as defined herein.

[0020] Those skilled in the art will appreciate that, unless otherwise stated, the singular forms "a," "an," "said," and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or groups thereof.

[0021] In the description of this specification, reference to the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and integrate different embodiments or examples described in this specification, as well as features of different embodiments or examples, unless otherwise inconsistent.

[0022] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0023] In the description of this specification, the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing the present technology 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 operate in a specific orientation. Therefore, they should not be understood as limiting the present technology.

[0024] Unless otherwise specified or limited, the terms "installed," "connected," "connected," and "disposed" should be understood broadly. For example, they may refer to fixed connection or disposition, detachable connection or disposition, or integral connection or disposition. Those skilled in the art will understand the specific meanings of these terms in this technology based on specific circumstances.

[0025] To facilitate understanding of the present invention, the present invention is further explained below with reference to specific embodiments in conjunction with the accompanying drawings. However, the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0026] Those skilled in the art should understand that the drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily necessary for implementing the present invention.

[0027] In order to achieve efficient and autonomous mud-water separation, the wastewater can flow and filter autonomously without any energy consumption, and will not cause membrane pollution and other effects, such as Figures 1 to 3As shown, an embodiment of the present invention provides an activated sludge bioreactor and a water treatment method based on self-filtration. By making full use of hydrophilic porous materials as self-filtration materials, and utilizing the excellent hydrophilic properties, low cost properties, and the dual influence of capillary action and gravity of the above materials, efficient and autonomous separation of sludge and wastewater is achieved. Due to the spatial exclusion effect of the hydrophilic material, large particles of sludge are excluded from the liquid phase body, and at the same time, the sludge will autonomously return to the liquid phase body by gravity during the self-filtration process. The above-mentioned autonomous exclusion spatial steric effect has many differences in principle compared to traditional membrane separation: 1) In terms of mass transfer mode. Membrane filtration relies on passive mass transfer (external pressure drive), and its main function is convection. Energy consumption is required, and pressure is used to transport the mud-water mixture to the membrane surface, and then forced separation is performed. In this way, all substances in the wastewater need to contact the membrane surface and then be intercepted and separated. Therefore, the separation pressure on the membrane surface is huge, and the membrane pollution potential is high. However, in the self-filtration system, mass transfer mainly relies on the capillary and gravity effects of the porous material (no external pressure drive). The mass transfer does not require external energy consumption. The separation process is driven autonomously by capillary action. Moreover, only water molecules can be utilized by capillary action. Large molecules such as sludge cannot produce capillary action and pass through the porous hydrophilic material at the same time. 2) Retention method and direction. During the membrane filtration process, the direction of passage of the entire mud-water mixture is perpendicular to the membrane surface from the outside to the inside. However, in the self-filtration system, the mud-water mixture is not forced to be transported to the material surface under the action of forced convection. Therefore, the sludge in the mud water moves downward under the action of gravity, and the water molecules climb upward along the porous hydrophilic material under the action of capillary action. At the same time, the steric hindrance of the porous material will further repel the sludge downward and settle to the bottom of the pool. This forms an efficient and autonomous separation of mud and water.

[0028] Based on the excellent properties of the aforementioned self-filtration mud-water separation system, anaerobic, anoxic, aerobic, and self-filtration separation zones were further established. Lightweight fillers were added to different zones to further enhance the biodiversity and sludge concentration of the activated sludge, achieve efficient denitrification, inhibit sludge bulking, and reduce sludge yield. This invention has developed a system that helps address operational and maintenance challenges such as the inability to use membrane bioreactors in confined spaces (such as high-speed trains, RVs, and ships), as well as membrane cleaning and frequent membrane replacement. This system achieves efficient wastewater treatment, autonomous filtration, and autonomous flow, which will be of great significance to the sustainability of transportation water systems.

[0029] The self-filtration activated sludge bioreactor comprises: a tank body, an aeration system, a self-filtration system, activated sludge in the tank body, and lightweight fillers and zero-valent iron powder added to the tank body; the tank body is divided into an anaerobic zone, an anoxic zone, an aerobic zone, and a self-filtration drainage zone by a partition along the water inlet direction; an aeration system is provided at the bottom of the aerobic zone, a self-filtration drainage zone is provided at the rear end, a sludge hopper and a sludge return pump are provided at the bottom of the drainage zone to return the sludge to the anaerobic zone of the tank body; the self-filtration drainage zone comprises a drainage trough, a self-filtration system suspended in an inverted U shape on the wall of the drainage trough, and ... self-filtration system. materials and a water collection tank; a Y-shaped support layer is set on the top of each drainage tank to control the water outlet height and turning angle of the self-filtration material; one end of the self-filtration material is immersed below the water surface of the aerobic zone, and the self-filtration material passes through the Y-shaped support layer along the length direction, and the other end is suspended on the water collection tank. The clear water in the sludge mixture first climbs upward under the action of capillary and spatial exclusion effects, then passes through an inverted U-shaped turn and flows into the water collection tank under the action of gravity. The sludge is intercepted by the self-filtration material due to the spatial steric effect and self-gravity, and returns to the inside of the aerobic zone.

[0030] The volume ratio of the anaerobic zone, anoxic zone, and aerobic zone is 1:1:1-1:1:5. The self-filtering material is various types of porous hydrophilic materials. The self-filtering material is pure cotton fabric, porous sponge, porous synthetic fiber cloth or porous activated carbon felt. The self-filtering material has a thickness of 0.2cm-10cm and an average pore size of 0.1μm-100μm. The front part of the self-filtering material is composed of a matrix and nanomaterials, wherein the nanomaterials are mainly nanometal oxide materials and nanocarbon materials, such as nanoiron oxide, nanozinc oxide, nanotitanium dioxide, carbon nanotubes, nanographene, etc., which can be used to improve the performance and efficiency of activated sludge. The lightweight filler is a porous filler made of high-density polyethylene HDPE and polyvinyl chloride PVC. The shape of the porous filler is cylindrical or cubic. The porosity of the porous filler is 30%-80%, and the hydrophilic angle is less than 60°. The zero-valent iron powder is high-purity reduced iron powder or hydroxy iron powder, with a particle size range of 0.5μm-500μm and a dosage of 0.1-1g / L.

[0031] Example 1

[0032] In this embodiment 1, a self-filtration activated sludge bioreactor is provided, comprising a rectangular tank body 1, an aeration system 2, a self-filtration system 3, activated sludge 4 in the tank body, a lightweight filler 5, and zero-valent iron powder. The tank body is divided into an anaerobic zone 7, an anoxic zone 8, an aerobic zone 9, and a self-filtration drainage zone 10 along the water inlet direction by a partition 6, forming a baffle + plug flow design. The aerobic zone is provided with an aeration system at the bottom, and a self-filtration drainage zone is provided at the rear end of the aerobic zone. A sludge hopper 11 and a sludge return pump 12 are provided at the bottom of the drainage zone to return the sludge to the anaerobic zone. In addition, the drainage zone is provided with multiple drainage troughs, each of which is provided with an inverted U-shaped self-filtration material on the wall, and a Y-shaped support layer 13 is provided on the upper part of the drainage trough to control the water outlet height (5 cm) and turning angle (30°) of the self-filtration material. One end of the self-filtration material is submerged below the water surface, and the other end is suspended in the air. The clean water in the sludge mixture first climbs upward under the action of capillary and spatial exclusion effects, then makes an inverted U-turn and flows into the sump 14 under the action of gravity. The sludge is intercepted by the self-filtration material due to the spatial exclusion effect and gravity and returns to the sludge hopper.

[0033] The volume ratio of the anaerobic zone to the anoxic zone to the aerobic zone was 1:1:4. The self-filtration material was activated carbon fiber felt, 0.2 cm thick and with an average pore size of 50 μm. The self-filtration material was loaded with nanomaterial, nano-titanium dioxide. The lightweight filler used in the cell was square porous HDPE (high-density polyethylene), with a porosity of 80% and a hydrophilic angle of 60°. Hydroxyl iron powder (100 μm in size) was also added to the cell at a dosage of 0.5 g / L.

[0034] In this embodiment 1, the wastewater treatment method using the above-mentioned self-filtration activated sludge bioreactor device includes:

[0035] (1) Taking domestic wastewater as the research object, after the wastewater undergoes alternating reactions in the anaerobic zone, anoxic zone, and aerobic zone, it is automatically filtered and the mud and water are automatically separated in the drainage area, achieving efficient sludge enrichment. Under the combined effects of the material's own capillary action, gravity, and spatial exclusion effect, the mud and water mixture climbs vertically upward under the capillary action of the internal pores of the porous material. After reaching an appropriate height, it passes through the Y-shaped support layer and then moves downward under the action of gravity, gradually merging into the water collection tank and being discharged as the final effluent. In addition, due to the different molecular weights of dissolved organic matter, during the self-filtration process, especially along the length of the self-filtration (i.e., the direction of water flow), the self-filtration material can be regarded as a plug-flow porous adsorber. Due to the material's own adsorption effect, a plug-flow adsorption effect also occurs, further promoting the deep adsorption and retention of organic matter of different molecular weights. On the contrary, while water molecules climb vertically upward, the sludge is trapped by the pore structure of the porous material itself, resulting in a spatial exclusion effect. As part of the sludge is trapped, a sludge filter layer is further formed on the outside of the porous material. This filter layer further hinders subsequent sludge from entering the interior of the porous material, thus forming a spontaneous dynamic membrane filtration system. More importantly, unlike traditional membrane filtration, in the self-filtration system, after receiving the exclusion effect, the sludge will spontaneously return to the sludge hopper under the action of gravity. Therefore, the differential mass transfer of "mud below the water" in the anisotropic mud-water separation effectively promotes mud-water separation and solves the problem of membrane fouling. When large suspended particles, hair, or foam appear in the wastewater, the self-filtration system can maintain efficient mud-water separation, has good resistance to water quality fluctuations, low requirements for influent pretreatment, and strong applicability to complex water quality.

[0036] (2) The wastewater is subjected to the high sludge concentration in the anaerobic-anoxic-aerobic zone through the suspension + biofilm + zero-valent iron coupling system, achieving efficient organic matter removal while strengthening endogenous denitrification and simultaneous chemical phosphorus removal. The activated sludge in (1) is efficiently retained within the tank by the self-filtration system, and the lightweight filler further increases the sludge volume, allowing the sludge concentration to reach 10g / L. The wastewater is thoroughly mixed with the return sludge in the anaerobic zone, effectively promoting the growth of dominant bacterial communities. Anaerobic phosphorus uptake and partial denitrification occur in the anaerobic zone. Denitrification is further enhanced after the wastewater enters the anoxic zone. Due to the high sludge concentration and limited oxygen mass transfer within the lightweight filler, simultaneous homogeneous and heterogeneous endogenous denitrification occurs, achieving efficient nitrogen removal without the need for an external carbon source, reducing sludge discharge intensity and subsequent sludge treatment issues. When the wastewater enters the aerobic zone, organic matter is efficiently oxidized to CO2 by the high-concentration sludge and lightweight filler biofilm, producing proliferating sludge. Simultaneously, phosphate is excessively released by phosphate-accumulating bacteria under aerobic conditions. It is fully adsorbed by the hydroxyl iron produced on the surface of the zero-valent iron powder to produce iron phosphate precipitation, further promoting sludge precipitation. The zero-valent iron core is encapsulated by the sludge, increasing the sludge specific gravity and enhancing sludge settling performance. This further promotes self-filtration mud-water separation and encourages the sludge to quickly fall off the surface of the self-filtration material and return to the sludge hopper. Nano-titanium dioxide is loaded onto self-filtration materials, leveraging its catalytic and photocatalytic properties to promote the degradation of activated sludge. Nano-titanium dioxide exhibits excellent catalytic and photocatalytic activity, accelerating the degradation of organic pollutants in wastewater. Through photocatalytic or catalytic reactions, nano-titanium dioxide breaks down organic pollutants into harmless substances while simultaneously enhancing the reduction and dephosphorization capabilities of microorganisms within the activated sludge, improving dephosphorization effectiveness and increasing activated sludge treatment efficiency.

[0037] Ultimately, the phosphorus removal rate in the treated wastewater was 90%, the total nitrogen removal rate was 80%, and the COD removal rate was 90%.

[0038] Example 2

[0039] In this embodiment 2, a self-filtration activated sludge bioreactor is provided, comprising a rectangular tank body 1, an aeration system 2, a self-filtration system 3, activated sludge 4 in the tank body, a lightweight filler 5, and zero-valent iron powder. The tank body is divided into an anaerobic zone 7, an anoxic zone 8, an aerobic zone 9, and a self-filtration drainage zone 10 along the water inlet direction by a partition 6, forming a baffle + plug flow design. The aerobic zone is provided with an aeration system at the bottom, and a self-filtration drainage zone is provided at the rear end of the aerobic zone. A sludge hopper 11 and a sludge return pump 12 are provided at the bottom of the drainage zone to return the sludge to the anaerobic zone. In addition, the drainage zone is provided with multiple drainage troughs, each of which has an inverted U-shaped self-filtration material on the wall, and a Y-shaped support layer 13 is provided on the upper part of the drainage trough to control the water outlet height (10 cm) and the turning angle (45°) of the self-filtration material. One end of the self-filtration material is immersed below the water surface, and the other end is suspended in the air. The clean water in the sludge mixture first climbs upward under the action of capillary and spatial exclusion effects, then makes an inverted U-turn and flows into the sump 14 under the action of gravity. The sludge is intercepted by the self-filtration material due to the spatial exclusion effect and gravity and returns to the sludge hopper.

[0040] The volume ratio of the anaerobic zone to the anoxic zone to the aerobic zone was 1:1:5. The filter material was a porous cotton cloth with a thickness of 0.3 cm and an average pore size of 10 μm. The lightweight filler used in the cell was a round porous polyvinyl chloride with a porosity of 40% and a hydrophilic angle of 80°. Zero-valent iron powder with a particle size of 10 μm was also added to the cell at a dosage of 0.1 g / L.

[0041] In this embodiment 2, the above-mentioned self-filtration activated sludge bioreactor device is used to implement a wastewater treatment method, including:

[0042] (1) Taking domestic wastewater as the research object, after the wastewater undergoes alternating reactions in the anaerobic zone, anoxic zone, and aerobic zone, it is automatically filtered and the mud and water are automatically separated in the drainage area, achieving efficient sludge enrichment. Under the combined effects of the material's own capillary action, gravity, and spatial exclusion effect, the mud and water mixture climbs vertically upward under the capillary action of the internal pores of the porous material. After reaching an appropriate height, it passes through the Y-shaped support layer and then moves downward under the action of gravity, gradually merging into the water collection tank and being discharged as the final effluent. In addition, due to the different molecular weights of dissolved organic matter, during the self-filtration process, especially along the length of the self-filtration (i.e., the direction of water flow), the self-filtration material can be regarded as a plug-flow porous adsorber. Due to the material's own adsorption effect, a plug-flow adsorption effect also occurs, further promoting the deep adsorption and retention of organic matter of different molecular weights. On the contrary, while water molecules climb vertically upward, the sludge is trapped by the pore structure of the porous material itself, resulting in a spatial exclusion effect. As part of the sludge is trapped, a sludge filter layer is further formed on the outside of the porous material. This filter layer further hinders subsequent sludge from entering the interior of the porous material, thus forming a spontaneous dynamic membrane filtration system. More importantly, unlike traditional membrane filtration, in the self-filtration system, after receiving the exclusion effect, the sludge will spontaneously return to the sludge hopper under the action of gravity. Therefore, the differential mass transfer of "mud below the water" in the anisotropic mud-water separation effectively promotes mud-water separation and solves the problem of membrane fouling. When large suspended particles, hair, or foam appear in the wastewater, the self-filtration system can maintain efficient mud-water separation, has good resistance to water quality fluctuations, low requirements for influent pretreatment, and strong applicability to complex water quality.

[0043] (2) The wastewater is subjected to the high sludge concentration in the anaerobic-anoxic-aerobic zone through the suspension + biofilm + zero-valent iron coupling system, achieving efficient organic matter removal while strengthening endogenous denitrification and simultaneous chemical phosphorus removal. The activated sludge in (1) is efficiently retained within the tank by the self-filtration system, and the lightweight filler further increases the sludge volume, allowing the sludge concentration to reach 8g / L. The wastewater is thoroughly mixed with the return sludge in the anaerobic zone, effectively promoting the growth of dominant bacterial communities. Anaerobic phosphorus uptake and partial denitrification occur in the anaerobic zone. Denitrification is further enhanced after the wastewater enters the anoxic zone. Due to the high sludge concentration and limited oxygen mass transfer within the lightweight filler, simultaneous homogeneous and heterogeneous endogenous denitrification occurs, achieving efficient nitrogen removal without the need for an external carbon source, reducing sludge discharge intensity and subsequent sludge treatment issues. When the wastewater enters the aerobic zone, organic matter is efficiently oxidized to CO2 by the high-concentration sludge and lightweight filler biofilm, producing proliferating sludge. Simultaneously, phosphate is excessively released by phosphate-accumulating bacteria under aerobic conditions. It is fully adsorbed by the hydroxyl iron produced on the surface of the zero-valent iron powder to produce iron phosphate precipitation, further promoting sludge precipitation. The zero-valent iron core is encapsulated by the sludge, increasing the sludge specific gravity and enhancing sludge settling performance. This further promotes self-filtration mud-water separation and encourages the sludge to quickly fall off the surface of the self-filtration material and return to the sludge hopper. Nano-zinc oxide is loaded onto self-filtration materials to improve the toxicity resistance of activated sludge, enhance its degradation capacity, and reduce the pollutant content of the sludge. Nano-zinc oxide can produce reactive oxygen species, such as hydroxyl radicals, which oxidize and reduce organic matter and heavy metals in the sludge. It can also stimulate the activity of microorganisms in the sludge and improve the biodegradation efficiency of the sludge.

[0044] Ultimately, the phosphorus removal rate in the treated wastewater was 93%, the total nitrogen removal rate was 85%, and the COD removal rate was 88%.

[0045] Example 3

[0046] In this embodiment 3, a self-filtration activated sludge bioreactor is provided, comprising a rectangular tank body 1, an aeration system 2, a self-filtration system 3, activated sludge 4 in the tank body, a lightweight filler 5, and zero-valent iron powder. The tank body is divided into an anaerobic zone 7, an anoxic zone 8, an aerobic zone 9, and a self-filtration drainage zone 10 along the water inlet direction by a partition 6, forming a baffle + plug flow design. The aerobic zone is provided with an aeration system at the bottom, and a self-filtration drainage zone is provided at the rear end of the aerobic zone. A sludge hopper 11 and a sludge return pump 12 are provided at the bottom of the drainage zone to return the sludge to the anaerobic zone. In addition, the drainage zone is provided with multiple drainage troughs, each of which has an inverted U-shaped self-filtration material on the wall, and a Y-shaped support layer 13 is provided on the upper part of the drainage trough to control the water outlet height (15 cm) and the turning angle (45°) of the self-filtration material. One end of the self-filtration material is submerged below the water surface, and the other end is suspended in the air. The clean water in the sludge mixture first climbs upward under the action of capillary and spatial exclusion effects, then makes an inverted U-turn and flows into the sump 14 under the action of gravity. The sludge is intercepted by the self-filtration material due to the spatial exclusion effect and gravity and returns to the sludge hopper.

[0047] The volume ratio of the anaerobic zone to the anoxic zone to the aerobic zone was 1:1:5. The filter material was porous activated carbon felt with a thickness of 0.5 cm and an average pore size of 1 μm. The lightweight filler used in the cell was cylindrical porous HDPE (high-density polyethylene) with a porosity of 70% and a hydrophilic angle of 50°. Hydroxyl iron powder (50 μm in size) was also added to the cell at a dosage of 0.75 g / L.

[0048] In this embodiment 3, the method for treating wastewater using the self-filtration activated sludge bioreactor device includes:

[0049] (1) Taking domestic wastewater as the research object, after the wastewater undergoes alternating reactions in the anaerobic zone, anoxic zone, and aerobic zone, it is automatically filtered and the mud and water are automatically separated in the drainage area, achieving efficient sludge enrichment. Under the combined effects of the material's own capillary action, gravity, and spatial exclusion effect, the mud and water mixture climbs vertically upward under the capillary action of the internal pores of the porous material. After reaching an appropriate height, it passes through the Y-shaped support layer and then moves downward under the action of gravity, gradually merging into the water collection tank and being discharged as the final effluent. In addition, due to the different molecular weights of dissolved organic matter, during the self-filtration process, especially along the length of the self-filtration (i.e., the direction of water flow), the self-filtration material can be regarded as a plug-flow porous adsorber. Due to the material's own adsorption effect, a plug-flow adsorption effect also occurs, further promoting the deep adsorption and retention of organic matter of different molecular weights. On the contrary, while water molecules climb vertically upward, the sludge is trapped by the pore structure of the porous material itself, resulting in a spatial exclusion effect. As part of the sludge is trapped, a sludge filter layer is further formed on the outside of the porous material. This filter layer further hinders subsequent sludge from entering the interior of the porous material, thus forming a spontaneous dynamic membrane filtration system. More importantly, unlike traditional membrane filtration, in the self-filtration system, after receiving the exclusion effect, the sludge will spontaneously return to the sludge hopper under the action of gravity. Therefore, the differential mass transfer of "mud below the water" in the anisotropic mud-water separation effectively promotes mud-water separation and solves the problem of membrane fouling. When large suspended particles, hair, or foam appear in the wastewater, the self-filtration system can maintain efficient mud-water separation, has good resistance to water quality fluctuations, low requirements for influent pretreatment, and strong applicability to complex water quality.

[0050] (2) The wastewater is subjected to the high sludge concentration in the anaerobic-anoxic-aerobic zone through the suspension + biofilm + zero-valent iron coupling system, achieving efficient organic matter removal while strengthening endogenous denitrification and simultaneous chemical phosphorus removal. The activated sludge in (1) is efficiently retained within the tank by the self-filtration system, and the lightweight filler further increases the sludge volume, allowing the sludge concentration to reach 10g / L. The wastewater is thoroughly mixed with the return sludge in the anaerobic zone, effectively promoting the growth of dominant bacterial communities. Anaerobic phosphorus uptake and partial denitrification occur in the anaerobic zone. Denitrification is further enhanced after the wastewater enters the anoxic zone. Due to the high sludge concentration and limited oxygen mass transfer within the lightweight filler, simultaneous homogeneous and heterogeneous endogenous denitrification occurs, achieving efficient nitrogen removal without the need for an external carbon source, reducing sludge discharge intensity and subsequent sludge treatment issues. When the wastewater enters the aerobic zone, organic matter is efficiently oxidized to CO2 by the high-concentration sludge and lightweight filler biofilm, producing proliferating sludge. Simultaneously, phosphate is excessively released by phosphate-accumulating bacteria under aerobic conditions. It is fully adsorbed by the hydroxyl iron produced on the surface of the zero-valent iron powder to produce iron phosphate precipitation, further promoting sludge precipitation. The zero-valent iron core is encapsulated by the sludge, increasing the sludge specific gravity and enhancing sludge settling performance. This further promotes self-filtration mud-water separation and encourages the sludge to quickly fall off the surface of the self-filtration material and return to the sludge hopper. Loading carbon nanotubes onto self-filtration materials can enhance their adsorption and conductivity. Nanocarbon materials have a large specific surface area and high electrical conductivity, effectively adsorbing organic pollutants and heavy metal ions in wastewater and improving the conductivity of the self-filtration material. Furthermore, carbon nanotubes can act as electron carriers, promoting electron transfer among anaerobic microorganisms in sludge, enabling electrochemical oxidation and reduction of the sludge while also generating usable energy such as electricity and hydrogen. This helps enhance the adsorption and electrochemical treatment of activated sludge.

[0051] Ultimately, the phosphorus removal rate in the treated wastewater was 92%, the total nitrogen removal rate was 85%, and the COD removal rate was 91%.

[0052] In summary, the self-filtration activated sludge bioreactor and water treatment method described in the embodiments of the present invention have the following advantages:

[0053] 1) This device efficiently combines key technologies such as anaerobic, anoxic, aerobic, and biofilm carrier enrichment with the self-filtration system. Through the baffle + plug flow design, on the one hand, it reduces the risk of wastewater short-circuiting. At the same time, the plug flow reactor can effectively promote the chemical potential of organic matter oxidation in wastewater, promote microorganisms to form dominant strains in different environments, and use lightweight fillers to strengthen the biofilm system and suspended activated sludge to construct a complex microbial community and ecology, providing a dominant bacterial structure for denitrification and phosphorus removal.

[0054] 2) The development of the self-filtration system eliminates the membrane materials used in traditional membrane bioreactors and utilizes cheap and simple porous flexible materials as water-conducting materials to achieve pumpless filtration of wastewater, greatly reducing the energy consumption of water pumps in traditional membrane filtration processes. More importantly, the filtration form of the self-filtration system is significantly different from that of traditional membrane filtration. The directional flow of water and sludge is achieved through the autonomous and active filtration of muddy water in the wastewater. That is, water is discharged from the body along the porous filter material under the action of capillary action, and the sludge moves in the opposite direction of the water flow under the dual effects of the exclusion effect generated by the porous filter material and gravity. The above-mentioned reverse mass transfer characteristics of muddy water ensure that even at high sludge concentrations, the retained sludge will not affect the flow of clean water, and will autonomously leave the self-filtration system by gravity, achieving autonomous separation of sludge and wastewater.

[0055] 3) This device is more conducive to methodological design. At the same time, different materials and different materials can be selected according to different scenarios. For example, cheap materials such as sponges, fabrics, and discarded fabrics can be used in the self-filtration system, which greatly reduces costs and realizes waste resource utilization.

[0056] 4) Compared to traditional membrane bioreactors, self-filtration systems have greater potential for fouling resistance. This is especially true for sediment, hair, foam, and other materials that are not conducive to traditional membrane filtration materials. Due to the active mass transfer characteristics of self-filtration systems driven by capillary action, these complex fixed objects are not driven by capillary action, thus achieving autonomous separation and self-fouling resistance. They are also highly tolerant to water quality fluctuations, require less pretreatment, and have strong applicability and stability.

[0057] 5) Based on the self-filtration performance, sludge concentration and sludge concentration are achieved, and the sludge enters the nutrient level at a low F / M, so that the sludge is in the endogenous denitrification stage. It not only has the advantages of low sludge yield and no need for external carbon source, but also has the performance of energy saving, low consumption, and pump-free operation, providing new ideas for the development of sustainable biochemical wastewater treatment technology.

[0058] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solutions disclosed in the present invention without the need for creative work should be included in the scope of protection of the present invention.

Claims

1. A self-filtration activated sludge bioreactor, characterized in that: include: The tank body, aeration system, self-filtration system, activated sludge in the tank body, and lightweight fillers and zero-valent iron powder added to the tank body; the tank body is divided into anaerobic zone, anoxic zone, aerobic zone, and self-filtration drainage zone by partitions along the water inlet direction; an aeration system is provided at the bottom of the aerobic zone, and a sludge hopper and a sludge return pump are provided at the bottom of the self-filtration drainage zone to return the sludge to the anaerobic zone of the tank body; the self-filtration drainage zone includes a drainage trough, a self-filtration material suspended in an inverted U shape on the wall of the drainage trough, and a water collection trough; a Y-shaped support layer is provided on the top of each drainage trough to control the water outlet height and turning angle of the self-filtration material; one end of the self-filtration material is immersed below the water surface of the self-filtration drainage zone, and the self-filtration material is suspended along the length direction. After passing through the Y-shaped support layer, the other end is suspended on the drainage trough. The clean water in the sludge mixture first climbs upward under the action of capillary and spatial exclusion effects, then makes an inverted U-shaped turn and flows into the sump under the action of gravity. The sludge is intercepted by the self-filtration material due to the spatial steric effect and gravity, and returns to the sludge hopper; the self-filtration material is pure cotton fabric, porous sponge, porous synthetic fiber cloth or porous activated carbon felt, and the front part of the self-filtration material is loaded with nanomaterials, wherein the nanomaterials are nanometal oxide materials and nanocarbon materials; the nanometal oxide materials are nanoiron oxide, nanozinc oxide or nanotitanium dioxide; the nanocarbon materials are carbon nanotubes or nanographene.

2. The self-filtration activated sludge bioreactor according to claim 1, characterized in that: The volume ratio of the anaerobic zone, the anoxic zone and the aerobic zone is 1:1:1-1:1:

5.

3. The self-filtration activated sludge bioreactor according to claim 1, characterized in that: The self-filtering material has a thickness of 0.2 cm to 10 cm and an average pore size of 0.1 μm to 100 μm.

4. The self-filtration activated sludge bioreactor according to claim 1, characterized in that: The lightweight filler is a porous filler made of high-density polyethylene (HDPE) or polyvinyl chloride (PVC).

5. The self-filtration activated sludge bioreactor according to claim 4, characterized in that: The shape of the porous filler is cylindrical or cubic.

6. The self-filtration activated sludge bioreactor according to claim 4, characterized in that: The porosity of the porous filler is 30%-80%, and the hydrophilic angle is less than 60°.

7. The self-filtration activated sludge bioreactor according to claim 1, characterized in that: The zero-valent iron powder is high-purity reduced iron powder with a particle size range of 0.5 μm-500 μm and a dosage of 0.1-1 g / L.

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