A device and method for reducing membrane fouling and energy consumption of aerobic granular sludge MBR

Abstract

The present application relates to sewage treatment technical field, especially a kind of device and method for reducing aerobic granular sludge MBR membrane pollution and energy consumption, including anaerobic zone, aerobic zone and anoxic zone, anaerobic zone and anoxic zone are arranged side by side in parallel, anaerobic zone, aerobic zone and anoxic zone are sequentially connected according to water flow direction;Sludge in anaerobic zone is in satiation state, anaerobic zone size is less than anoxic zone size and aerobic zone size respectively;Aerobic zone is equipped with multiple aeration units for supplying oxygen to sludge and increasing hydraulic shear force;Sludge in the end of aerobic zone and anoxic zone is in hunger state, anoxic zone is equipped with vibrating membrane assembly, vibrating membrane assembly generates low amplitude vibration to make membrane filament and water body form relative motion.The present application utilizes vibrating MBR bioreactor, can avoid high shear force caused by strong aeration, combined with satiation-hunger and sludge screening design, can promote the formation of aerobic granular sludge, membrane assembly retains sludge, saves secondary sedimentation tank.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an apparatus and method for reducing membrane fouling and energy consumption in aerobic granular sludge MBR. Background Technology

[0002] Wastewater treatment is a typical high-energy-consuming industry and a significant source of global carbon emissions. Under the backdrop of "carbon peaking and carbon neutrality," the water industry urgently needs to develop and apply synergistic technologies for pollution reduction and carbon reduction to support the green and low-carbon development of wastewater treatment.

[0003] Aerobic granular sludge technology is considered one of the most promising biological wastewater treatment technologies, possessing a dense granular structure, good settling performance, and high biomass and activity. Aerobic granular sludge exhibits an oxygen distribution gradient from the inside out, forming a coupled structure of anaerobic, anoxic, and aerobic processes, thus enabling the simultaneous removal of organic matter, nitrogen, and phosphorus, significantly improving pollutant degradation capacity. Furthermore, aerobic granular sludge produces less sludge and settles faster than traditional activated sludge processes, thus significantly reducing land area and operating costs. Currently, aerobic granular sludge is primarily cultivated in sequencing batch reactors (SBRs), which is incompatible with the existing continuous flow wastewater treatment plant operation mode. Compared to SBR aerobic granular sludge, continuous flow aerobic granular sludge technology has greater research value and application potential; however, its stability and start-up time are difficult to control and resolve.

[0004] Membrane bioreactors (MBRs) are a technology that combines biological treatment units with membrane separation units. This technology can maintain a high sludge concentration within the bioreactor, reduce floor space, improve effluent quality, and reduce sludge production, and has been widely used in the water industry. However, MBRs generally require high aeration intensity to flush the membrane fiber surface or the use of high-pressure pumps to provide pressure differentials to combat membrane fouling, thus resulting in high energy consumption. The characteristics of aerobic granular sludge can significantly reduce membrane pore fouling, and coupling aerobic granular sludge with membrane bioreactors offers a possibility for controlling membrane fouling.

[0005] MBR (Mechanical Bioreactor) systems require high aeration intensities to flush the membrane fibers and mitigate fouling; however, aerobic granular sludge is prone to disintegration under high aeration. Using different aeration intensities in the biological treatment and membrane separation zones can slow sludge disintegration, but providing high aeration intensities is energy-intensive. Furthermore, aerobic granular sludge processes typically operate in an anaerobic-aerobic mode; therefore, before mature granular sludge is formed, the system may lack sufficient anoxic zones, resulting in insufficient denitrification capacity. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a device and method for reducing membrane fouling and energy consumption in aerobic granular sludge MBR. By utilizing a vibrating MBR bioreactor, the high shear force caused by strong aeration can be avoided. Combined with saturation-starvation and sludge screening design, the formation of aerobic granular sludge can be promoted. The membrane module retains sludge, saving the secondary sedimentation tank. The anoxic tank maintains a high sludge concentration, eliminating the need for sludge return from the bottom of the secondary sedimentation tank to the anoxic zone, resulting in a simpler structure.

[0007] The objective of this invention is achieved through the following technical solution: A device for reducing membrane fouling and energy consumption in aerobic granular sludge MBR includes an anaerobic zone, an aerobic zone, and an anoxic zone, wherein the anaerobic zone and the anoxic zone are arranged in parallel side by side, and the anaerobic zone, aerobic zone, and anoxic zone are connected sequentially in the direction of water flow. The sludge in the anaerobic zone is in a saturated state, and the size of the anaerobic zone is smaller than the size of the anoxic zone and the aerobic zone, respectively. The aerobic zone is equipped with multiple aeration units for supplying oxygen to the sludge and increasing hydraulic shear force. The sludge in the anoxic zone is in a state of starvation. The anoxic zone is equipped with a vibrating membrane assembly, which generates low-amplitude vibrations to cause the membrane fibers to move relative to the water.

[0008] Furthermore, the aeration unit includes an aeration disc disposed at the bottom of the aerobic zone and a blower connected to the aeration disc, wherein the blower is disposed outside the aerobic zone.

[0009] Furthermore, the diaphragm assembly is driven by a motor.

[0010] Furthermore, the anaerobic zone is equipped with a stirrer.

[0011] Furthermore, a sludge hopper is provided in the anoxic zone, and the sludge hopper is connected to the anaerobic zone through a sludge return pipe.

[0012] Furthermore, the anoxic zone is provided with a sludge hopper installation part and a membrane module installation part. The surface of the sludge hopper installation part is lower than that of the membrane module installation part. The sludge hopper is disposed in the sludge hopper installation part, and the top surface of the sludge hopper is flush with the surface of the membrane module installation part. The vibrating diaphragm assembly is disposed at the diaphragm assembly mounting section.

[0013] Furthermore, multiple vibrating diaphragm assemblies are provided, and the multiple vibrating diaphragm assemblies are distributed in a rectangular array.

[0014] Furthermore, the hydraulic retention time of the anaerobic zone is 1h-3h, the hydraulic retention time of the aerobic zone is 4h-6h, and the hydraulic retention time of the anoxic zone is 4h-6h.

[0015] Furthermore, the volume of the anaerobic zone is less than 1 / 4 of the total volume of the anaerobic zone, aerobic zone, and anoxic zone.

[0016] A wastewater treatment method based on a device for reducing membrane fouling and energy consumption in aerobic granular sludge MBRs includes the following steps: Step 1: Wastewater continuously flows into the anaerobic zone and is thoroughly mixed with sludge by the agitator to form a mud-water mixture. The sludge makes full use of the organic matter in the influent and converts some of the organic matter into an internal carbon source, while simultaneously achieving anaerobic phosphorus release. Step 2: The mud-water mixture from Step 1 enters the aerobic zone. Under aerobic conditions, the organic matter in the mud-water mixture is transformed and degraded, and some nitrogen and phosphorus are removed through microbial assimilation. At the same time, driven by the hydraulic shear force generated by the aeration unit and the alternating conditions of saturation and starvation, the microorganisms secrete extracellular polymers. Step 3: The mud-water mixture from Step 2 is introduced into the anoxic zone. The vibrating membrane component traps the sludge, increasing the sludge concentration in the anoxic zone. At the same time, the vibrating membrane component generates low-amplitude vibrations, causing the membrane fibers to move relative to the water. The aerobic granular sludge with good settling performance settles to the bottom of the anoxic zone first under the action of the vibrating membrane component and gravity, thus achieving sludge screening. Step 4: Return the aerobic granular sludge that settled to the bottom of the anoxic zone in Step 3 to the anaerobic zone.

[0017] The beneficial effects of this invention are: 1) This invention utilizes a vibrating MBR bioreactor, which can avoid the high shear force caused by strong aeration. Combined with the saturation-starvation and sludge screening design, it can promote the formation of aerobic granular sludge. The membrane module intercepts sludge, saving the secondary sedimentation tank. The anoxic tank maintains a high sludge concentration, eliminating the need for sludge return from the bottom of the secondary sedimentation tank to the anoxic zone, resulting in a simpler structure.

[0018] 2) At the same time, it ensures that during the start-up phase (before particles are formed), the system has a sufficient anoxic environment for denitrification, which further improves the denitrification effect of the system and helps to ensure that the effluent meets the standards stably; 3) Aerobic granular sludge operating in continuous flow mode has lower operating costs, is easier to operate, and has a larger wastewater treatment capacity than sequencing batch aerobic granular sludge, thus it has greater research value and application potential.

[0019] 4) The overall configuration is closer to that of a wastewater treatment plant operating in AAO mode, and the engineering modification is relatively simple.

[0020] 5) It improves the sludge screening effect, and sludge with good settling performance is preferentially returned to obtain organic matter in the influent, which is conducive to promoting the formation of aerobic granular sludge. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the device for reducing membrane fouling and energy consumption in aerobic granular sludge MBR in an embodiment of the present invention. Figure 2 Cross-sectional views of the aerobic and hypoxic zones; In the diagram, 1 is the anaerobic zone; 2 is the aerobic zone; 3 is the anoxic zone; 4 is the aeration unit; 5 is the vibrating membrane assembly; 6 is the aeration disc; 7 is the blower; 8 is the agitator; 9 is the sludge hopper; and 10 is the sludge return pipe. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] See Figures 1-2 The present invention provides a technical solution: Example 1: like Figure 1 and Figure 2 As shown, a device for reducing membrane fouling and energy consumption in aerobic granular sludge MBR includes an anaerobic zone 1, an aerobic zone 2, and an anoxic zone 3. The anaerobic zone 1 and the anoxic zone 3 are arranged in parallel side by side, and the anaerobic zone 1, the aerobic zone 2, and the anoxic zone 3 are connected sequentially in the direction of water flow. The sludge in the anaerobic zone 1 is in a saturated state, and the size of the anaerobic zone 1 is smaller than the size of the anoxic zone 3 and the size of the aerobic zone 2, respectively. The aerobic zone 2 is equipped with multiple aeration units 4 for supplying oxygen to the sludge and increasing hydraulic shear force. The sludge at the end of the aerobic zone 2 and in the anoxic zone 3 is in a state of starvation. The anoxic zone 3 is equipped with a vibrating membrane assembly 5, which generates low-amplitude vibrations to create relative motion between the membrane fibers and the water (thus scouring the membrane fibers). The vibrating membrane assembly 5 intercepts the sludge, and under the combined action of the force provided by its reciprocating motion and vertical gravity, the aerobic granular sludge with better settling performance will preferentially settle to the bottom. Therefore, the membrane separation zone also has a screening function for intercepting sludge.

[0024] The aeration unit 4 includes an aeration disc 6 disposed at the bottom of the aerobic zone 2 and a blower 7 connected to the aeration disc 6. The blower 7 is disposed outside the aerobic zone 2.

[0025] The vibrating diaphragm assembly 5 is driven by a motor.

[0026] The anaerobic zone 1 is equipped with a stirrer 8. Wastewater continuously flows into the anaerobic zone 1 and is thoroughly mixed with the sludge under the action of the stirrer 8. The sludge in the anaerobic zone 1 has sufficient usable organic matter, and the sludge can make full use of the organic matter in the influent and convert some of the organic matter into an internal carbon source, while simultaneously achieving anaerobic phosphorus release.

[0027] The anoxic zone 3 is equipped with a sludge hopper 9, which is connected to the anaerobic zone 1 via a sludge return pipe 10. The sludge hopper 9, together with the sludge return pipe 10 and an air-lift device (the air-lift device is existing technology, and its working principle and specific structure will not be described in detail here) realizes the return of sludge to the anaerobic zone 1.

[0028] The anoxic zone 3 is provided with a sludge hopper installation part and a membrane module installation part. The surface of the sludge hopper installation part is lower than that of the membrane module installation part. The sludge hopper 9 is disposed in the sludge hopper installation part, and the top surface of the sludge hopper 9 is flush with the surface of the membrane module installation part. The vibrating membrane assembly 5 is disposed at the membrane assembly mounting section. This arrangement facilitates the entry of sludge trapped by the vibrating membrane assembly 5 into the sludge hopper 9.

[0029] Multiple vibrating diaphragm assemblies 5 are provided, and the multiple vibrating diaphragm assemblies 5 are distributed in a rectangular array.

[0030] The hydraulic retention time of the anaerobic zone 1 is 1h-3h, the hydraulic retention time of the aerobic zone 2 is 4h-6h, and the hydraulic retention time of the anoxic zone 3 is 4h-6h.

[0031] The volume of anaerobic zone 1 is less than 1 / 4 of the total volume of anaerobic zone 1, aerobic zone 2 and anoxic zone 3.

[0032] Working principle: (1) Wastewater flows continuously into anaerobic zone 1 and is fully mixed with sludge under the action of stirrer 8 to form sludge-water mixture. The sludge in anaerobic zone 1 has sufficient available organic matter (the sludge is in a saturated state). The sludge can make full use of the organic matter in the influent and convert some of the organic matter into internal carbon source, while realizing anaerobic phosphorus release.

[0033] (2) The sludge-water mixture enters the aerobic zone 2. Under aerobic conditions, aerobic microorganisms can further transform and degrade organic matter, and remove some nitrogen and phosphorus through microbial assimilation. The aeration unit 4 in the aerobic zone 2 provides oxygen to the sludge while increasing the hydraulic shear force. The concentration of organic matter entering the aerobic zone 2 is low, and the sludge is mainly in a state of starvation. Driven by hydraulic shear force and alternating saturation and starvation conditions, microorganisms can secrete more extracellular polymers, which is conducive to the formation and maintenance of aerobic granular sludge.

[0034] (3) The sludge-water mixture continues to enter the anoxic zone 3, and the effluent is separated by the membrane module and discharged into the subsequent treatment unit. Due to the retention effect of the vibrating membrane module 5, the anoxic zone 3 has a high sludge concentration, and the sludge can make full use of the stored internal carbon source to achieve efficient denitrification.

[0035] (4) The membrane module generates a slight horizontal reciprocating motion driven by a motor, which causes relative motion between the membrane fibers and the water body, thereby reducing membrane fouling. Compared with traditional aeration-type membrane fouling control technology, the vibration type can significantly reduce operating energy consumption while achieving membrane fouling control.

[0036] Because aerobic granular sludge has a faster settling velocity than flocculent sludge, under the combined action of the force provided by the reciprocating motion of the vibrating membrane module 5 and vertical gravity, the aerobic granular sludge with better settling performance will preferentially settle to the bottom. Therefore, the membrane separation zone also has a screening function for the intercepted sludge.

[0037] The aerobic granular sludge that settles to the bottom is returned to the front anaerobic zone 1 via an airlift device. Under the action of the agitator 8, it is completely mixed with the influent, fully absorbing and utilizing the organic matter in the influent.

[0038] Activated sludge undergoes three stages: anaerobic, aerobic, and anoxic. In the smaller anaerobic zone 1, microorganisms have access to more organic matter and are in a saturated environment. In the aerobic zones 2 and 3, the available organic matter in the wastewater is less, and the hydraulic time is longer, placing the microorganisms in a prolonged starvation phase. This alternating cycle promotes the conversion of more organic matter into internal carbon sources in the anaerobic zone 1. Simultaneously, the alternation of saturation and starvation encourages the secretion of more extracellular polymeric substances (EPS), leading to continuous microbial aggregation. Under suitable hydraulic shear force and sludge screening, the aggregated sludge exhibits better settling properties, preferentially settling to the bottom and being returned to the influent. This cycle continues, ultimately forming dense granular sludge. In traditional activated sludge-MBR bioreactors, the strong aeration and scouring easily disperse the microbial aggregates, making granular sludge formation more difficult. Using a vibrating MBR bioreactor can avoid the high shear force caused by strong aeration. Combined with a saturated-starved and sludge screening design, it can promote the formation of aerobic granular sludge.

[0039] This invention utilizes membrane modules to trap sludge, saving the need for a secondary sedimentation tank. The anoxic tank maintains a high sludge concentration, eliminating the need for sludge return from the bottom of the secondary sedimentation tank to the anoxic zone 3, resulting in a simpler structure.

[0040] At the same time, it ensures that during the start-up phase (before particles are formed), the system has a sufficient anoxic environment for denitrification, which further improves the denitrification effect of the system and helps to ensure that the effluent meets the standards stably; Continuous flow aerobic granular sludge has lower operating costs, is easier to operate, and has a larger wastewater treatment capacity than sequencing batch aerobic granular sludge, thus it has greater research value and application potential.

[0041] Its overall configuration is closer to that of a wastewater treatment plant operating in AAO mode, and the engineering modification is relatively simple.

[0042] It improves the sludge screening effect, and sludge with good settling performance is preferentially returned to obtain organic matter in the influent, which is conducive to promoting the formation of aerobic granular sludge.

[0043] Example 2: A wastewater treatment method based on a device for reducing membrane fouling and energy consumption in aerobic granular sludge MBRs includes the following steps: Step 1: Wastewater continuously flows into anaerobic zone 1 and is thoroughly mixed with sludge under the action of mixer 8 to form sludge-water mixture. The sludge makes full use of the organic matter in the influent and converts some of the organic matter into an internal carbon source, while realizing anaerobic phosphorus release. Step 2: The mud-water mixture from Step 1 enters the aerobic zone 2. Under aerobic conditions, the organic matter in the mud-water mixture is transformed and degraded, and some nitrogen and phosphorus are removed through microbial assimilation. At the same time, driven by the hydraulic shear force generated by the aeration unit 4 and the alternating conditions of saturation / starvation, the microorganisms secrete extracellular polymers. Step 3: The mud-water mixture from Step 2 is introduced into the anoxic zone 3. The vibrating membrane component 5 intercepts the sludge, increasing the sludge concentration in the anoxic zone 3. At the same time, the vibrating membrane component 5 generates low-amplitude vibration, causing the membrane fibers to move relative to the water. The aerobic granular sludge with good settling performance settles to the bottom of the anoxic zone 3 first under the action of the vibrating membrane component 5 and gravity, thereby achieving sludge screening. Step 4: Return the aerobic granular sludge that settled to the bottom of the anoxic zone 3 in Step 3 to the anaerobic zone.

[0044] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A device for reducing membrane fouling and energy consumption in aerobic granular sludge MBR systems, characterized in that: It includes an anaerobic zone, an aerobic zone, and an anoxic zone. The anaerobic zone and the anoxic zone are arranged side by side in parallel. The anaerobic zone, the aerobic zone, and the anoxic zone are connected in sequence according to the direction of water flow. The sludge in the anaerobic zone is in a saturated state, and the size of the anaerobic zone is smaller than the size of the anoxic zone and the aerobic zone, respectively. The aerobic zone is equipped with multiple aeration units for supplying oxygen to the sludge and increasing hydraulic shear force. The sludge at the end of the aerobic zone and in the anoxic zone is in a state of starvation. The anoxic zone is equipped with a vibrating membrane assembly, which generates low-amplitude vibration to make the membrane fibers move relative to the water. The volume of the anaerobic zone is less than 1 / 4 of the total volume of the anaerobic zone, aerobic zone, and anoxic zone; The hydraulic retention time in the anaerobic zone is 1-3 hours, the hydraulic retention time in the aerobic zone is 4-6 hours, and the hydraulic retention time in the anoxic zone is 4-6 hours.

2. The device for reducing membrane fouling and energy consumption in aerobic granular sludge MBRs according to claim 1, characterized in that: The aeration unit includes an aeration disc located at the bottom of the aerobic zone and a blower connected to the aeration disc, wherein the blower is located outside the aerobic zone.

3. The device for reducing membrane fouling and energy consumption in aerobic granular sludge MBRs according to claim 1, characterized in that: The vibrating diaphragm assembly is driven by a motor.

4. The device for reducing membrane fouling and energy consumption in aerobic granular sludge MBRs according to claim 1, characterized in that: The anaerobic zone is equipped with a stirrer.

5. The device for reducing membrane fouling and energy consumption in aerobic granular sludge MBRs according to claim 1, characterized in that: The anoxic zone is equipped with a sludge hopper, which is connected to the anaerobic zone through a sludge return pipe.

6. The device for reducing membrane fouling and energy consumption in aerobic granular sludge MBR according to claim 5, characterized in that: The anoxic zone is provided with a sludge hopper installation part and a membrane module installation part. The surface of the sludge hopper installation part is lower than that of the membrane module installation part. The sludge hopper is disposed inside the sludge hopper installation part, and the top surface of the sludge hopper is flush with the surface of the membrane module installation part. The vibrating diaphragm assembly is disposed at the diaphragm assembly mounting section.

7. The device for reducing membrane fouling and energy consumption in aerobic granular sludge MBR according to claim 6, characterized in that: Multiple diaphragm assemblies are provided, and the multiple diaphragm assemblies are distributed in a rectangular array.

8. A wastewater treatment method based on the apparatus for reducing membrane fouling and energy consumption in aerobic granular sludge MBRs according to any one of claims 1-7, characterized in that: Includes the following steps: Step 1: Wastewater continuously flows into the anaerobic zone and is thoroughly mixed with sludge by the agitator to form a mud-water mixture. The sludge makes full use of the organic matter in the influent and converts some of the organic matter into an internal carbon source, while simultaneously achieving anaerobic phosphorus release. Step 2: The mud-water mixture from Step 1 enters the aerobic zone. Under aerobic conditions, the organic matter in the mud-water mixture is transformed and degraded, and some nitrogen and phosphorus are removed through microbial assimilation. At the same time, driven by the hydraulic shear force generated by the aeration unit and the alternating conditions of saturation / starvation, the microorganisms secrete extracellular polymers. Step 3: The mud-water mixture from Step 2 is introduced into the anoxic zone. The vibrating membrane component traps the sludge, increasing the sludge concentration in the anoxic zone. At the same time, the vibrating membrane component generates low-amplitude vibrations, causing the membrane fibers to move relative to the water. The aerobic granular sludge with good settling performance settles to the bottom of the anoxic zone first under the action of the vibrating membrane component and gravity, thus achieving sludge screening. Step 4: Return the aerobic granular sludge that settled to the bottom of the anoxic zone in Step 3 to the anaerobic zone.

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