MBR filter and its containerized wastewater purification system

Abstract

The present invention discloses an MBR filter and its containerized wastewater purification system. The MBR filter comprises a multilayer device consisting of a first filter membrane layer, a first cloth pad layer, a first purified water cavity layer, a support frame layer, a second purified water cavity layer, a second cloth pad layer, and a second filter membrane layer, which are arranged in parallel in sequence. A sealed frame made of plastic material is provided on the periphery of the multilayer device, and a water outlet is provided on the upper side of the sealed frame. The filter membrane layer is capable of filtering wastewater, and the cloth pad layer is made of carbon fiber cloth to which a power supply electrode can be connected. The electric field formed between multiple adjacent MBR filters arranged in parallel can oscillate and remove sludge adhered to each filter membrane. The device has a strong wastewater treatment capacity, the filter membrane is easy to self-clean, and can be made into a mobile integrated wastewater treatment device.

Description

Technical Field

[0001] The invention relates to wastewater treatment equipment and a treatment technology thereof. Background Art

[0002] In the field of wastewater treatment, membrane filtration systems rely on a pressure differential between the two sides of the membrane, forcing wastewater through membranes of varying pore sizes to achieve filtration. They are widely popular due to their high treatment capacity, excellent effluent quality, and lack of secondary pollution. In actual use, membrane surface contamination and pore blockage are the most common problems, making membrane cleaning a critical issue. Membrane cleaning methods primarily fall into two categories: physical and chemical. The cleaning method should be selected based on the module configuration, membrane material, contaminant type, and degree of contamination.

[0003] MBR membrane filtration is a novel water treatment technology that combines membrane separation units and / or biological treatment units. The membrane structures used primarily include flat sheet membranes and hollow fiber membranes. However, the application of MBR to different wastewater treatment types and the restoration of membrane function require more sophisticated design and improvement.

[0004] Invention No. 202011530790.6 discloses a wastewater treatment container, comprising a container with a filter device fixedly connected to the inner bottom of the container. An insulation box is installed to the right of the filter device. An aeration tank is connected to the interior of the insulation box. An airflow duct is connected to the bottom of the inner cavity of the aeration tank, and the upper end of the airflow duct is fixedly connected to the aeration device. This invention provides a mobile wastewater treatment device, and this structure can be used as a reference for this application.

[0005] The April 2020 issue of Membrane Science and Technology, titled "Research Progress on Electric Field Control of MBR Membrane Fouling," introduced a membrane bioreactor (MBR) with excellent effluent quality for direct reuse. However, membrane fouling during long-term operation remains a major obstacle to its further development and commercial application. Electric fields are an effective and clean way to mitigate membrane fouling and improve effluent quality. The key to utilizing the MBR's self-generated electric field to mitigate membrane fouling lies in the preparation of conductive microfiltration membranes. While the article does not clearly disclose the electric field structure and its raw materials, it may provide valuable insights into the filtration facilities of this application. Summary of the Invention

[0006] Purpose of the invention: To provide an MBR filter that can be flexibly moved and used, is particularly suitable for the treatment of printing and dyeing wastewater, has a self-cleaning function, and a containerized wastewater purification system thereof.

[0007] Technical solution:

[0008] The MBR filter of the present invention comprises a multilayer device consisting of a first filter membrane layer, a first cushion layer, a first purified water cavity layer, and a support skeleton layer arranged in parallel in sequence; or a multilayer device consisting of a first filter membrane layer, a first cushion layer, a first purified water cavity layer, a support skeleton layer, a second purified water cavity layer, a second cushion layer, and a second filter membrane layer arranged in parallel in sequence.

[0009] The outer periphery of the multilayer device is provided with a sealed frame made of plastic material (such as ABS material); the upper side of the sealed frame is provided with a water outlet which can be connected to a water outlet pipeline.

[0010] During operation, the MBR filter is immersed in a wastewater tank containing biologically activated sludge, which contains aerobic microorganisms that oxidize and degrade organic matter in the wastewater. The wastewater then passes through the filter membrane layer and enters the purified water chamber. Organic matter is trapped outside the filter membrane layer and continues to be degraded by the biologically activated sludge. The resulting purified water (or recycled water that can be recycled in the printing and dyeing production line) is then discharged through the outlet into the outlet pipe.

[0011] An aeration device is pre-installed at the bottom of the wastewater pool. Aeration blows the biologically activated sludge, supplying oxygen to aerobic microorganisms while stirring the sludge to prevent sludge accumulation or even clogging the filter membrane surface.

[0012] The filter membrane layer is a polymeric membrane, which is categorized by pore size, from coarse to fine, as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), or reverse osmosis (RO). The wastewater filtration membrane is a corrosion-resistant and temperature-resistant polymer membrane such as PVDF (preferably polyvinylidene chloride (PVDC), which has high barrier properties and is suitable for selective permeability membranes. It offers lower manufacturing costs than tetrafluoroethylene (PTFE) and greater heat and aging resistance than polyvinyl chloride (PVC). Its molecules also possess greater polarity, which, when used in conjunction with an electric field, facilitates the movement and separation of polar organic molecules, anions and cations, anion and cation clusters, and water molecules from the membrane surface).

[0013] The support skeleton layer is made of non-metallic material (non-conductive, preventing leakage, preferably ABS material with good formability and high cost performance).

[0014] The cushion layer is thicker than the filter membrane layer and has a larger pore size than the filter membrane. It is closely attached to or close to the filter membrane layer and has a lining or buffering effect on the filter membrane layer. The support skeleton layer has a supporting and fixing effect on the other two layers.

[0015] After long-term use, the surface of the MBR filter membrane may adhere to sludge. In addition to the bubbles blown out by aeration to stir the sludge and prevent sedimentation, there are also the following self-cleaning methods:

[0016] The fabric padding layer is a carbon fiber cloth padding (carbon fiber cloth or felt, serving as both an inner lining and a conductive electrode), which can be connected to one electrode of a power source (pulsed DC or AC with a long cycle, and equipped with a controller and power switch). Multiple MBR filters are arranged in parallel adjacent to each other (with spacing less than the thickness of the purified water chamber layer) in the wastewater tank. Adjacent carbon fiber cloth padding layers are connected to (or spaced apart from each other) the positive and negative electrodes of the power source. The multiple positive electrodes of the power sources are connected together to the positive electrode of the main power source; the multiple negative electrodes of the power sources are connected together to the negative electrode of the main power source. This creates a parallel plate electric field A with a small spacing between the membrane layers of two adjacent filters, and a parallel plate electric field B with a large spacing between the two membrane layers of the same filter. The electric field between adjacent MBR filters (this field is located between the two membranes, preventing electrolytes in the wastewater or sludge from contacting the electrodes and adsorbing on the electrode surfaces of the carbon fiber cloth or felt padding layer, thus maintaining good conductivity) has a greater attraction or repulsion force on electrolyte ions or ion clusters in the sludge than the electric field within the same MBR filter.

[0017] Since the field strength of the parallel plate electric field A is greater than the field strength of the parallel plate electric field B (constant or oscillating, the oscillation causes the positive and negative poles to exchange frequently, and the anions, cations and their groups accompany the oscillation), the anions, cations or their groups in the activated sludge or wastewater will move toward the positive or negative pole or vibrate back and forth under the action of the electric field, making it difficult for the activated sludge to accumulate or adhere to the outer wall surface of the filter membrane.

[0018] In the present invention, there can be 2-3 wastewater pools, which are, according to the wastewater entry route, the first oxidation pool, or the second oxidation pool (the two are connected in series for further oxidation and degradation, thereby increasing the degradation effect of organic molecules), and the filtration pool; the microbial oxidation and membrane filtration functions are carried out separately, so that the oxidation and decomposition are thorough, the microorganisms basically do not contact the power supply electrodes, and maintain good biological activity.

[0019] Moreover, the voltage at the two poles of the electric field (the voltage can overcome the ionization potential energy of most polluting compounds in the sludge - the voltage required for ionization, less than 36V safety voltage) forms an electric field or current in the sludge or wastewater, which removes the sludge accumulated or adhered to the filter membrane, while causing the microorganisms in the sludge to die by electric shock in the filter membrane pool, reducing the pollution caused by remaining microorganisms.

[0020] In this invention, the wastewater tank and its control unit, inlet piping, inlet pump, outlet piping, outlet pump, aeration piping, and air compressor can all be placed in a container shell in a specific order, facilitating lifting and transportation for wastewater treatment at various locations. After the wastewater tank is drained (a small amount of wastewater sludge can be retained to maintain microbial activity), the empty container is hoisted and placed in place, where the wastewater enters the purification process.

[0021] Preferably, an insulation layer is embedded between the stainless steel thin-walled wastewater tank and the container shell, which not only provides insulation but also forms a sandwich composite material structure to enhance the mechanical properties of the wastewater tank wall and the container shell, thereby reducing the wall thickness and lightening the weight.

[0022] Furthermore, preferably, the water inlet pipe, water outlet pipe, and aeration pipe are buried in the insulation layer, which is both hidden and beautiful and protects the pipes from freezing in winter. The water inlet pump, water outlet pump, and air compressor pump are exposed in the equipment room for easy operation and maintenance.

[0023] In the present invention, the top of the electric control room is not cut, and a door for operators to enter and exit is opened on the side box; the top of the equipment room is not cut, and a door for operators to enter and exit is opened on the side box; the tops of the oxidation tank and the membrane tank are open for easy placement (can be equipped with a cover plate).

[0024] In this invention, a raised cofferdam surrounds the container's upper perimeter to protect personnel working on microbial addition and maintenance. A water baffle is welded to the container's opening edge to prevent rainwater from flowing back into the container. The tops of the oxidation tank and membrane filter tank inside the container are flanged and bolted to the raised cofferdam, facilitating lifting, transportation, or fixed connections.

[0025] Beneficial effects:

[0026] Containerized integrated wastewater treatment equipment has the advantages of stable and reliable technical performance, good treatment effect, low investment, small footprint, and easy maintenance. The equipment can be connected to a car to make it a mobile integrated wastewater treatment equipment, which is easy to carry and move.

[0027] The MBR filter has a large specific surface area and a strong filter membrane adhesion capacity. Under the same organic matter load conditions, it has a high organic matter filtration and removal rate.

[0028] The carbon fiber cloth pads of two adjacent MBR filters are connected to the positive and negative poles of a pulsed DC or AC power supply respectively. The pulsed electric field or alternating electric field formed therebetween causes the polar substances in the sludge or the electrolytes in the wastewater to be subjected to the pulsed or alternating electric field force, causing them to move (positive ions move to the negative pole, negative ions move to the positive pole) or oscillate. The sludge is not easy to adhere to the surface of the filter membrane or is easy to desorb, thus avoiding sludge particles from clogging the filter pores of the filter membrane and ensuring that the filter membrane can be reused for a long time.

[0029] The electrical control room can test and control the temperature of the incoming wastewater. The microorganisms in the oxidation tank are adsorbed in the sludge, and the organic matter in the wastewater becomes nutrients for the microorganisms. In addition, the aeration device adds fresh air, and the survival rate of microorganisms is high, which has the characteristics of the activated sludge method. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1This is a schematic diagram of the three-dimensional structure of an MBR filter of the present invention when it is partially used;

[0031] Figure 2 This is a schematic diagram of the partial three-dimensional structure of another MBR filter of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of multiple MBR filters arranged in parallel in a wastewater tank according to the present invention;

[0033] Figure 4 It is a schematic diagram of the partial internal structure of the containerized wastewater treatment system of the present invention;

[0034] Figure 5 yes Figure 4 Schematic diagram of the partial longitudinal section structure of a medium container.

[0035] In all figures, 1-water outlet pipe; 2-water outlet; 3-MBR filter; 4-frame; 5-first filter membrane layer; 6-first cushion layer; 7-first purified water chamber layer; 8-support skeleton layer; 9-second purified water chamber layer; 10-second cushion layer; 11-second filter membrane layer; 12-bubbles; 13-sludge; 14-aeration pipe; 15-positive power supply; 16-negative power supply; 17-first oxidation tank; 18-second oxidation tank; 19-filtration tank (membrane tank); 20-electrical control room; 21-equipment room; 24-container cofferdam; 25-water retaining plate; 26-container bottom plate; 27-water inlet pump; 28-water outlet pump; 29-air compressor pump. DETAILED DESCRIPTION

[0036] Example 1:

[0037] like Figure 1 The MBR filter shown has seven layers of devices arranged in parallel, which are composed of a first filter membrane layer 5, a first cushion layer 6, a first purified water chamber layer 7, a thermoplastic plastic support skeleton layer 8, a second purified water chamber layer 9, a second cushion layer 10, and a second filter membrane layer 11. The seven-layer device is surrounded by a sealed frame 4 made of plastic material, and a water outlet 2 is provided on the upper side of the sealed frame 4.

[0038] The filter membrane layers 5 and 11 are polymer filter membranes PVDF ultrafiltration membranes, which can filter organic wastewater from the textile or chemical industry to obtain purified water; the purified water cavity layers 7 and 9 can collect the purified water that passes through the filter membrane layers 5 and 11 and discharge it from the water outlet 2 on the frame 4.

[0039] When used in wastewater, the activated sludge particles containing microorganisms in contact with the surface of the ultrafiltration membrane can oxidize and degrade organic matter in the wastewater; at the same time, under the blowing of aeration entering the aeration pipe 14, oxygen is supplemented, making the microorganisms active, and causing the sludge particles to roll up and down, so as not to be adsorbed on the surface of the filter membrane to block the filter pores, thereby maintaining a good filtration capacity.

[0040] Example 2:

[0041] like Figure 2 The two MBR filters shown are arranged in parallel and facing each other (with the filter membrane layers close to each other). Each MBR filter 3 comprises four parallel layers: a first filter membrane layer 5, a first fabric cushion layer 6, a first purified water chamber layer 7, and an ABS support frame layer 8. The four layers are surrounded by a sealed ABS frame 4, with a water outlet 2 on its upper side. The filter membrane layer 5 is a high-molecular-weight PVDC nanofiltration membrane capable of filtering organic wastewater from the printing and dyeing industry to produce purified water. The purified water chamber layer 7 collects the purified water that passes through the filter membrane layer 5 and discharges it through the water outlet 2 on the frame 4.

[0042] The cloth padding layer 6 is made of carbon fiber felt. The carbon fiber cloth padding layer in one MBR filter 3 is connected to a positive electrode 15 of a pulse power supply, while the carbon fiber cloth padding layer in the other MBR filter 3 is connected to a negative electrode 16 of the power supply. When the filtering capacity of the filter 3 decreases, the pulse power supply is turned on, forming a pulsed electric field between the positive electrode 15 and the negative electrode 16. The positive and negative ions of the electrolytes in the wastewater or activated sludge migrate toward the respective electrodes, desorbing impurities adhering to the two nanofiltration membranes, unclogging the filter pores of the membranes, and restoring the wastewater filtering function.

[0043] Example 3:

[0044] like Figure 3 The wastewater treatment device shown is composed of seven MBR filters 3 arranged in parallel, with wastewater inlet space left between adjacent MBR filters 3, and the water outlet above each MBR filter 3 is connected to the purified water pipeline.

[0045] The wastewater treatment device is placed in the membrane filter pool 19. According to the wastewater inlet route, it is sequentially arranged into the first oxidation pool 17, or the second oxidation pool 18, and the membrane filter pool 19, so that the microbial oxidation degradation of the wastewater and the filtration function of the wastewater are separated.

[0046] The wastewater treatment device described above constitutes a containerized wastewater purification system of the MBR filter 3. The electric control room 20, oxidation ponds 17, 18, membrane filter pool 19, and equipment room 21 are sequentially arranged on the bottom plate 26 of the container and inside the outer shell.

[0047] The first oxidation tank 17, second oxidation tank 18, and filter tank 19, each made of stainless steel, measure 2m (width) x 2m (length) x 2.5m (height). The container's outer shell is slightly larger in width and height than the stainless steel tanks and is 10 meters long.

[0048] On one side of the container shell, a 2-meter-long electric control room 20 is set up. The electric control room 20 has personnel entrances and exits and electric control instruments. The electric control instruments are connected with signal lines and collect status parameters of the oxidation pools 17, 18 and the membrane filter pool 19. The electric control instruments are connected with control lines and control the start and stop of the water inlet pump 27, the water outlet pump 28 and the air compressor pump 29.

[0049] On the other side of the container shell, a 2-meter-long equipment room 21 is set up. The equipment room 21 has a personnel entrance and exit and an inlet pump 27, an outlet pump 28, and an air compressor pump 29; the inlet pump 27 is connected to the oxidation ponds 17 and 18 through an inlet pipe, the outlet pump 28 is connected to the membrane filter pond 19 through an outlet pipe 1, and the air compressor pump 29 is connected to the oxidation ponds 17 and 18 through an aeration pipe 14 at the bottom of the oxidation ponds 17 and 18.

[0050] On one side of the container in the width direction, leave about 30 cm of space for installing pipes, including the water inlet pipe in the middle, the water outlet pipe 1 above, and the aeration pipe 14 below.

[0051] Such a containerized wastewater purification system can be moved to the required location to carry out flexible and mobile small-scale wastewater treatment projects.

Claims

1. A wastewater treatment device with an MBR filter, comprising, according to the wastewater inlet route, a first oxidation pond (17), a membrane filter pond (19), or a first oxidation pond (17), a second oxidation pond (18), and a membrane filter pond (19); wherein the microbial oxidation degradation of the wastewater is performed separately from the filtration function of the wastewater, wherein aerobic microbial strains are placed in the oxidation pond, and two or more parallel-arranged MBR filters (3) are placed in the membrane filter pond (19); The MBR filter has a multi-layer device, a sealed frame (4) made of plastic material is provided on the periphery of the multi-layer device, and a water outlet (2) is provided on the side of the sealed frame (4); The multilayer device comprises a first filter membrane layer (5), a first cushion layer (6), a first purified water cavity layer (7), a support skeleton layer (8), a second purified water cavity layer (9), a second cushion layer (10), and a second filter membrane layer (11) arranged in parallel in sequence; the first filter membrane layer (5) and the second filter membrane layer (11) are both polymer filter membranes capable of filtering wastewater to obtain purified water; the support skeleton layer (8) has a supporting and fixing effect on the other layers; the first purified water cavity layer (7) can collect purified water that passes through the first filter membrane layer (5), and the second purified water cavity layer (9) can collect purified water that passes through the second filter membrane layer (11), and both are discharged from the water outlet (2) on the frame (4); Its characteristics are: The first cloth pad layer (6) and the second cloth pad layer (10) are both made of carbon fiber cloth or carbon fiber felt, one of the adjacent cloth pad layers is connected to the positive electrode (15) of the power supply, and the other cloth pad layer is connected to the negative electrode (16) of the power supply; two or more positive electrodes (15) of the power supply are connected together to connect to the positive electrode of the total power supply; two or more negative electrodes (16) of the power supply are connected together to connect to the negative electrode of the total power supply; the voltage between the two electrodes of the power supply is greater than the voltage required for the ionization of most polluting compounds in the sludge and less than the safety voltage of 36V; A parallel plate electric field A with a smaller spacing is formed between the filter membrane layers of two adjacent MBR filters, and a parallel plate electric field B with a larger spacing is formed between the two filter membrane layers of the same MBR filter; the field strength of the parallel plate electric field A is greater than the field strength of the parallel plate electric field B.

2. The wastewater treatment device of the MBR filter according to claim 1, characterized in that: The first filter membrane layer (5) or the second filter membrane layer (11) of the MBR filter is made of PVDC material.

3. A containerized wastewater treatment plant with an MBR filter, characterized by: A wastewater treatment device using the MBR filter described in claim 1 or 2, further comprising a container, an electric control room (20), and an equipment room (21); the electric control room (20), an oxidation pond, a membrane filter pond (19), and the equipment room (21) are sequentially arranged on the bottom plate (26) of the container and inside the outer shell; the electric control room (20) has a personnel entrance and exit and an electric control instrument, the electric control instrument is respectively connected with a signal line and collects the status parameters of the oxidation pond and the membrane filter pond (19), and the electric control instrument is respectively connected with a control line and controls the start and stop of the water inlet pump (27), the water outlet pump (28), and the air pressure pump (29); the equipment room (21) has a personnel entrance and exit and a water inlet pump (27), a water outlet pump (28), and an air pressure pump (29); the water inlet pump (27) is connected to the oxidation pond through an inlet pipe, the water outlet pump (28) is connected to the membrane filter pond (19) through an outlet pipe (1), and the air pressure pump (29) is connected to the oxidation pond through an aeration pipe (14) at the bottom of the oxidation pond.

4. The containerized wastewater treatment plant of the MBR filter according to claim 3, characterized in that: An insulation layer is provided between the outer walls of the oxidation pond and the membrane filter pond (19) and the outer shell of the container, forming a sandwich composite material structure to reinforce the wastewater pond wall and the outer shell of the container; an inlet pipe and an outlet pipe (1) are respectively buried in the insulation layer.

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