AnDMBR dynamic membrane assembly for sludge anaerobic digestion

Abstract

The application discloses an AnDMBR dynamic membrane assembly for sludge anaerobic digestion, which comprises a sealed membrane frame, a plurality of flat plate membranes and a plurality of detachable aeration pipes; the sealed membrane frame is used for bearing various components of the AnDMBR dynamic membrane assembly and is in the shape of a cuboid composed of a stainless steel grid; the plurality of flat plate membranes are arranged in parallel and equidistantly in the sealed membrane frame; a membrane water outlet is arranged above the flat plate membranes, and the height of the membrane water outlet is higher than the upper surface of the sealed membrane frame; the gap between the plurality of flat plate membranes is filled with conductive particles; the plurality of detachable aeration pipes utilize the circulating biogas from the air guide holes to form a cross flow on the surface of the flat plate membranes and disturb the conductive particles between the flat plate membranes. The application effectively solves the problem of flat plate membrane surface mud cake deposition caused by the operation of AnDMBR at high sludge concentration, prolongs the service life of the dynamic membrane assembly, and improves the anaerobic digestion performance of the reactor.

Description

Technical Field

[0001] This invention belongs to the field of anaerobic digestion technology for sludge, and relates to an AnDMBR dynamic membrane module for anaerobic digestion of sludge. Background Technology

[0002] Anaerobic dynamic membrane bioreactor (AnDMBR) is a water treatment technology that combines membrane separation technology with activated sludge process. As a key component of anaerobic dynamic membrane bioreactor for waste sludge treatment, the dynamic membrane module forms a dynamic membrane layer composed of sludge on the surface of the flat sheet membrane when applied to anaerobic sludge digestion. This layer concentrates and separates the digested sludge. By decoupling the hydraulic retention time (HRT) and solids retention time (SRT), the operating concentration can be increased. However, long-term operation with high sludge concentration will inevitably lead to an excessively thick dynamic membrane layer, causing the formation of a sludge cake on the membrane surface. This results in excessively high membrane pressure or low membrane flux, reducing the operating efficiency of the dynamic membrane and even rendering it unusable. Therefore, it is necessary to clean or replace the dynamic membrane module.

[0003] In conventional AnDMBR processes, biogas recirculation is generally used to create a cross-flow rate on the membrane surface to mitigate sludge deposition and control dynamic membrane fouling. However, using biogas recirculation alone to control membrane fouling has the following drawbacks: First, the sludge concentration and viscosity in the AnDMBR system are high, limiting the cross-flow rate created by biogas recirculation. Consequently, the resulting membrane shearing effect is limited, failing to effectively control dynamic membrane formation and necessitating frequent replacement or cleaning of the dynamic membrane modules. Second, the biogas recirculation rate depends on the sludge digestion efficiency. When digestion is poor, leading to insufficient biogas production, rapid sludge cake deposition on the membrane surface occurs, resulting in reduced AnDMBR system performance.

[0004] In view of the above, in order to effectively control dynamic membrane fouling, extend the service life of dynamic membrane modules, and reduce the frequency of cleaning or replacement of dynamic membrane modules, it is necessary to design a new dynamic membrane module that can effectively control dynamic membrane fouling, improve the anaerobic digestion efficiency of the system, reduce operating and management costs, and achieve long-term stable operation of the reactor. Summary of the Invention

[0005] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide an AnDMBR dynamic membrane module for anaerobic digestion of sludge. This module employs a closed membrane frame and adds conductive carbon-based particles into the gaps between the flat membranes. By utilizing circulating biogas to create cross-flow, the conductive carbon-based particles rub against the dynamic membrane layer composed of sludge formed on the surface of the flat membrane. The resulting membrane shear force peels off any excessively thick dynamic membrane layer, thereby maintaining the long-term stable operation of the reactor.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A first aspect of the present invention provides an AnDMBR dynamic membrane module for anaerobic digestion of sludge, comprising:

[0008] A sealed membrane frame is used to support the various components of the AnDMBR dynamic membrane module; the sealed membrane frame is a cuboid structure made of stainless steel mesh.

[0009] Multiple flat sheet membranes are arranged in parallel and equidistantly within the sealed membrane frame; a membrane outlet is provided above the flat sheet membrane, and the height of the membrane outlet is higher than the upper surface of the sealed membrane frame; conductive carbon-based particles are filled in the gaps between adjacent flat sheet membranes.

[0010] Multiple detachable aeration pipes are located below the sealed membrane frame, and multiple air guide holes are provided below the detachable aeration pipes; the detachable aeration pipes utilize the circulating biogas coming out of the air guide holes to form a crossflow on the surface of the flat membrane, disturbing the movement of conductive carbon-based particles between the flat membranes.

[0011] Preferably, the conductive carbon-based particles are activated carbon particles or biochar particles.

[0012] Preferably, the filling volume of the conductive carbon-based particles is 1 / 3 to 2 / 3 of the gap volume between adjacent flat films.

[0013] Preferably, the conductive carbon-based particles have a particle size of 0.2 to 1.0 cm.

[0014] Preferably, the circulation intensity of the biogas is 10–40 m³ / s. 3 / (m 2 ·h).

[0015] Preferably, the angle between the air guide hole below the aeration branch pipe and the vertical direction is 40-50°.

[0016] Preferably, the plurality of detachable aeration pipes are arranged parallel to each other at equal intervals below the sealed membrane frame, and the detachable aeration pipes are arranged perpendicular to the flat sheet membrane.

[0017] A second aspect of the present invention provides an AnDMBR dynamic membrane module for anaerobic digestion of sludge, comprising a sealed membrane frame, a plurality of flat sheet membranes arranged parallel and equidistantly within the sealed membrane frame, and a plurality of detachable aeration pipes disposed below the sealed membrane frame.

[0018] A membrane outlet is provided above the flat sheet membrane, and the height of the membrane outlet is higher than the upper surface of the sealed membrane frame; conductive particles are filled in the gap between adjacent flat sheet membranes.

[0019] Preferably, the conductive particles are selected from conductive iron-based particles.

[0020] Preferably, the conductive iron-based particles are selected from iron oxide particles.

[0021] Preferably, the iron oxide particles are magnetite particles or pyrite particles.

[0022] The AnDMBR dynamic membrane module for anaerobic digestion of sludge provided by this invention also has the following beneficial effects:

[0023] 1. The AnDMBR dynamic membrane module for anaerobic digestion of sludge of the present invention adopts a closed membrane frame and adds conductive particles (conductive carbon-based particles or conductive iron-based particles) in the gap between the flat membranes. The circulating biogas forms a cross flow, which causes the conductive particles to rub against the dynamic membrane layer composed of sludge formed on the surface of the flat membrane. The generated membrane shear force peels off the excessively thick dynamic membrane layer, thereby maintaining the long-term stable operation of the reactor.

[0024] 2. The AnDMBR dynamic membrane module for anaerobic digestion of sludge of the present invention effectively increases the interaction area between microorganisms and conductive particles by adding conductive particles, providing a growth substrate for microorganisms to attach to, and enhances the interspecies electron transfer of microorganisms by utilizing the conductivity of conductive particles, thereby improving the biogas yield of the AnDMBR system.

[0025] 3. The AnDMBR dynamic membrane module for anaerobic digestion of sludge of the present invention uses biogas circulation to agitate particles and cause them to rub against the membrane surface, thereby effectively controlling the formation of dynamic membrane, reducing the frequency of membrane module cleaning or replacement, extending the service life of the membrane module, and thus realizing the long-term operation of the reactor. It not only saves operating costs, but is also simple to implement, highly reliable, and can be promoted.

[0026] 4. The AnDMBR dynamic membrane module for anaerobic digestion of sludge of the present invention can effectively control the formation rate of dynamic membrane layer on the surface of flat sheet membrane, reduce the membrane cleaning frequency, and enable AnDMBR to operate stably for more than 50 days.

[0027] 5. The AnDMBR dynamic membrane module for anaerobic digestion of sludge of the present invention effectively solves the problem of sludge cake deposition on the surface of the dynamic membrane caused by the operation of AnDMBR under high sludge concentration. While extending the service life of the dynamic membrane, it also improves the anaerobic digestion performance of the system.

[0028] 6. The present invention also uses conductive iron-based particles as conductive particles, which improves the technical solution for mitigating membrane fouling, further expands the applicability of the present invention, thereby effectively controlling dynamic membrane fouling, extending the service life of dynamic membrane modules, and reducing the frequency of cleaning or replacement of dynamic membrane modules. Attached Figure Description

[0029] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0030] Figure 1 This is a schematic diagram of the structure of the AnDMBR dynamic membrane module for anaerobic digestion of sludge according to the present invention.

[0031] Figure 2 This is an exploded view of the AnDMBR dynamic membrane module for anaerobic digestion of sludge according to the present invention.

[0032] Figure 3 This is a cross-sectional schematic diagram of the internal structure of the AnDMBR dynamic membrane module for anaerobic digestion of sludge according to the present invention.

[0033] Figure 4 This invention relates to an anaerobic dynamic membrane bioreactor system employing AnDMBR dynamic membrane modules for anaerobic digestion of sludge.

[0034] In the diagram, 10 is a sealed membrane frame, 11 is a stainless steel mesh, 12 is conductive particles, 20 is a flat sheet membrane, 21 is a membrane outlet, 22 is a dynamic membrane layer, 30 is a detachable aeration pipe, 40 is a dynamic membrane separator, 41 is a circulating sludge outlet, 42 is a membrane separator sludge inlet, 50 is a biogas tank, 60 is the main reactor, 61 is a stirrer, 62 is the main reactor sludge inlet, 63 is the main reactor circulating sludge outlet, and 64 is the biogas outlet. Detailed Implementation

[0035] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with embodiments.

[0036] Combination Figure 1 , Figure 2As shown, the present invention provides an AnDMBR dynamic membrane module for anaerobic digestion of sludge, including a sealed membrane frame 10, a plurality of flat sheet membranes 20 disposed inside the sealed membrane frame 10, and a plurality of detachable aeration pipes 30 disposed below the sealed membrane frame 10. The sealed membrane frame 10 supports the various components of the AnDMBR dynamic membrane module, and is a cuboid structure composed of six stainless steel meshes 11. The plurality of flat sheet membranes 20 are arranged parallel and equidistantly within the sealed membrane frame 10; a membrane outlet 21 is provided above each flat sheet membrane 20, and the height of the membrane outlet 21 is higher than the upper surface of the sealed membrane frame 10. Conductive particles 12 are filled in the gaps between adjacent flat sheet membranes 20. Multiple detachable aeration pipes 30 are arranged parallel to the membrane surface of the flat sheet membrane 20. Each detachable aeration pipe 30 is fixed directly below the flat sheet membrane 20. Multiple air guide holes are provided diagonally below each detachable aeration pipe 30. In a specific embodiment, the angle between the air guide holes below the detachable aeration pipe 30 and the vertical direction is 40-45°. The detachable aeration pipe 30 utilizes the circulating biogas exiting from the air guide holes to create a crossflow on the surface of the flat sheet membrane 20, disturbing the movement of the conductive particles 12 between the flat sheet membranes 20. This causes friction between the conductive carbon-based particles 12 and the dynamic membrane layer 22 composed of digested sludge on the surface of the flat sheet membrane 20, thereby mitigating membrane fouling of the dynamic membrane module. Furthermore, the conductivity of the conductive carbon-based particles 12 can enhance the extracellular electron transfer efficiency of the methanogenic metabolic process of microbial symbiotic metabolism, thus improving the digestion effect.

[0037] In a specific embodiment, the flat sheet membrane 20 may be a double-sided flat sheet membrane, that is, membrane sheets are symmetrically arranged on both sides of the membrane skeleton, so as to avoid frequent cleaning or replacement of the module assembly and promote the rapid formation of dynamic membrane on the membrane assembly.

[0038] Combination Figure 2 , Figure 3 As shown, the conductive particles 12 are selected from conductive carbon-based particles, such as activated carbon particles or biochar particles; wherein the filling volume of the conductive particles 12 is 1 / 3 to 2 / 3 of the gap volume between adjacent flat sheet membranes 20, that is, when the area of ​​the flat sheet membrane 20 is a cm² 2 When the interval between adjacent flat films 20 is b cm, the filling volume of the conductive particles 12 is [(1 / 3 to 2 / 3) * a * b] cm. 3 The particle size of conductive particles 12 is 0.2–1.0 cm.

[0039] Multiple detachable aeration pipes 30 are arranged parallel and equidistantly below the sealed membrane frame. Each detachable aeration pipe is perpendicular to each flat membrane to further enhance the disturbance effect of the circulating biogas on the conductive particles 12. In this invention, the detachable aeration pipes 30 utilize the circulating biogas to disturb the conductive particles 12 (such as conductive carbon-based particles), and the circulation intensity of the circulating biogas from the aeration branch pipes is controlled to be 10–40 m³ / s. 3 / (m 2 This process creates a crossflow with a velocity of 0.1–0.3 m / s on the surface of the flat sheet membrane 20, causing friction between the conductive particles 12 (e.g., conductive carbon-based particles) and the dynamic membrane layer 22. This peels off the sludge cake layer on the surface of the flat sheet membrane 20, thereby controlling the formation of the dynamic membrane. Furthermore, since the conductive particles 12 (e.g., conductive carbon-based particles) have good conductivity, they can enhance the interspecies electron transfer efficiency between hydrolytic acidifying bacteria and methanogenic bacteria during anaerobic digestion, thereby improving the digestion effect and increasing the biogas yield of the AnDMBR system by 10%–30%.

[0040] Combination Figure 4 As shown, when the AnDMBR dynamic membrane module for anaerobic digestion of sludge of the present invention is used in an anaerobic dynamic membrane bioreactor, the AnDMBR dynamic membrane module for anaerobic digestion of sludge is fixed at the upper part of the dynamic membrane separator 40. After the remaining sludge is digested in the main reactor 60, it enters the dynamic membrane separator 40 through the sludge outlet 63 and the inlet 42 of the dynamic membrane separator. After the digested sludge is concentrated and separated by the AnDMBR dynamic membrane module, it is returned to the main reactor 60 through the circulating sludge outlet 41 of the dynamic membrane separator and the circulating sludge inlet 62 to continue anaerobic digestion. The AnDMBR dynamic membrane module for anaerobic digestion of sludge can be used in AnDMBR systems with a sludge concentration of 30-60 g / L in the dynamic membrane zone. It can effectively control the rate of sludge cake formation on the membrane surface, reduce the membrane cleaning frequency, and enable the anaerobic dynamic membrane bioreactor to operate stably for more than 50 days.

[0041] Considering the significant differences in anaerobic digestion processes under actual operating conditions, this invention also provides an AnDMBR dynamic membrane module for anaerobic digestion of sludge, which is largely similar to... Figure 1 , Figure 2The structure shown is the same, the main difference being the use of conductive iron-based particles as the conductive particles. These conductive iron-based particles function similarly to conductive carbon-based particles, enhancing electron transfer in microorganisms and thus increasing the biogas yield of the AnDMBR system. Specifically, this invention includes a sealed membrane frame, multiple flat sheet membranes arranged parallel within the sealed membrane frame, and multiple detachable aeration pipes located below the sealed membrane frame. A membrane outlet is located above the flat sheet membranes, with its height exceeding the upper surface of the sealed membrane frame; conductive particles are filled in the gaps between adjacent flat sheet membranes. The conductive particles are selected from conductive iron-based particles, which can be iron oxide particles, such as magnetite or pyrite particles; the particle size and filling volume of the conductive iron-based particles are within the same parameter range as those of the conductive carbon-based particles.

[0042] The following section provides a further description of an AnDMBR dynamic membrane module for anaerobic digestion of sludge, based on specific examples.

[0043] Example 1

[0044] In this embodiment, the AnDMBR dynamic membrane module described above for anaerobic digestion of sludge is used to concentrate and separate the sludge after anaerobic digestion:

[0045] The sludge concentration in the main reaction zone of the AnDMBR was 36.5 g / L, and the sludge concentration in the dynamic membrane separation zone was 43.3 g / L. Taking one set of parallel dynamic membrane modules as an example, there were four flat sheet membranes, each 20 cm long, 10 cm high, and 1 cm thick. The spacing between adjacent flat sheet membranes was 10 cm. A six-sided sealed membrane frame was prepared using stainless steel wire mesh. The distance between the flat sheet membranes and the sealed membrane frame was 5 cm. Approximately 100 cm³ of activated carbon particles with a particle size of 0.4–0.6 cm were added between adjacent flat sheet membranes. 3 Four detachable aeration pipes are installed at the bottom of the sealed membrane frame, parallel to the direction of the flat sheet membrane and equidistantly positioned directly below it, with a biogas circulation intensity of 30m³ / h. 3 / (m 2 At h), the outflow direction of the circulating biogas deviates from the vertical direction by 45°, and the diameter of the gas guide hole is 0.5 cm. Under the conditions of membrane flux of 5 LMH and transmembrane pressure difference of less than 10 kPa, the AnDMBR system can operate continuously and stably for more than 50 days without membrane cleaning, and the biogas yield increases from 0.58 L / g VS without the addition of activated carbon particles to 0.66 L / g VS.

[0046] Example 2

[0047] In this embodiment, the AnDMBR dynamic membrane module described above for anaerobic digestion of sludge is used to concentrate and separate the sludge after anaerobic digestion:

[0048] Similar to Example 1, the main difference is that the sludge concentration in the AnDMBR main reaction zone is 41.6 g / L, while the sludge concentration in the dynamic membrane zone is 51.0 g / L. Under conditions of a membrane flux of 5.3 LMH and a transmembrane pressure difference of less than 10 kPa, and a circulating biogas intensity of 35 m³ / h... 3 / (m 2 When the activated carbon granules are added, the AnDMBR system can operate continuously and stably for more than 50 days without membrane cleaning, and the biogas yield increases from 0.67 L / g VS without the addition of activated carbon granules to 0.76 L / g VS.

[0049] Example 3

[0050] The AnDMBR dynamic membrane module used in this embodiment for anaerobic digestion of sludge uses conductive iron-based particles as conductive particles for concentration and separation.

[0051] Similar to Example 1 in most respects, the difference being that approximately 130 cm of magnetite particles with a particle size of 0.4–0.8 cm were added between adjacent flat membranes. 3 The circulation intensity of the biogas is 30m. 3 / (m 2 (·h). Under conditions of 5 LMH membrane flux and less than 10 kPa transmembrane pressure difference, the AnDMBR system can operate continuously and stably for more than 50 days without membrane cleaning, and the biogas yield increases from 0.54 L / g VS without the addition of magnetite particles to 0.68 L / g VS.

[0052] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. An AnDMBR dynamic membrane assembly for anaerobic digestion of sludge, characterized in that, include: A sealed membrane frame is used to support the various components of the AnDMBR dynamic membrane module; The sealed membrane frame is a cuboid structure made of stainless steel mesh; Multiple flat sheet membranes are arranged in parallel and equidistantly within the sealed membrane frame; a membrane outlet is provided above the flat sheet membrane, and the height of the membrane outlet is higher than the upper surface of the sealed membrane frame; conductive carbon-based particles are filled in the gaps between adjacent flat sheet membranes. Multiple detachable aeration pipes are located directly below the sealed membrane frame. Multiple air guide holes are provided diagonally below each detachable aeration pipe. The angle between the air guide holes and the vertical direction is 40-50°. The detachable aeration pipes utilize the circulating biogas exiting from the air guide holes to create cross-flow on the flat sheet membrane surface, disturbing the movement of conductive carbon-based particles between the flat sheet membranes. This causes friction between the conductive carbon-based particles and the dynamic membrane layer composed of digested sludge on the flat sheet membrane surface, thereby mitigating membrane fouling of the dynamic membrane module. The conductivity of the conductive carbon-based particles also enhances the extracellular electron transfer efficiency of the methanogenic metabolic process of microbial symbiotic metabolism, thus improving the digestion effect. The detachable aeration pipe utilizes circulating biogas to agitate conductive particles, and controls the circulation intensity of the biogas to 10–40 m. 3 / (m 2 •h) A cross-flow velocity of 0.1 to 0.3 m / s is formed on the surface of the flat sheet membrane, which causes friction between the conductive particles and the dynamic membrane layer, and peels off the mud cake layer on the surface of the flat sheet membrane. This controls the formation of the dynamic membrane. Since the conductive particles have good conductivity, they enhance the interspecies electron transfer efficiency between hydrolytic acidifying bacteria and methanogenic bacteria during anaerobic digestion, thereby improving the digestion effect and increasing the biogas yield of the AnDMBR system by 10% to 30%.

2. The AnDMBR dynamic membrane assembly for sludge anaerobic digestion according to claim 1, characterized in that, The conductive carbon-based particles are activated carbon particles or biochar particles.

3. The An DMBR dynamic membrane assembly for sludge anaerobic digestion according to claim 2, characterized in that, The filling volume of the conductive carbon-based particles is 1 / 3 to 2 / 3 of the gap volume between adjacent flat films.

4. The An DMBR dynamic membrane assembly for sludge anaerobic digestion according to claim 3, characterized in that, The conductive carbon-based particles have a particle size of 0.2–1.0 cm.

5. The An DMBR dynamic membrane assembly for sludge anaerobic digestion according to any one of claims 1 to 4, characterized in that, The plurality of detachable aeration pipes are arranged parallel to each other at equal intervals below the sealed membrane frame, and the detachable aeration pipes are arranged perpendicular to the flat membrane.

6. The An DMBR dynamic membrane assembly for sludge anaerobic digestion according to claim 1, characterized in that, The conductive particles are selected from conductive iron-based particles.

7. The An DMBR dynamic membrane assembly for sludge anaerobic digestion according to claim 6, characterized in that, The conductive iron-based particles are selected from iron oxide particles.

8. The An DMBR dynamic membrane assembly for sludge anaerobic digestion according to claim 7, characterized in that, The iron oxide particles are selected from magnetite particles or pyrite particles.

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