Novel biogas slurry membrane filtration device based on silicon carbide membrane

Abstract

The invention discloses a novel biogas slurry membrane filtration device based on a silicon carbide membrane, which comprises: a silicon carbide membrane assembly, the silicon carbide membrane assembly is formed by connecting four membrane groups in parallel, and the two ends of the four membrane groups are respectively connected with a shunt pipe and a trunk pipe; each group of membrane group comprises four silicon carbide tubular membrane tubes, the four silicon carbide tubular membrane tubes are connected in series, each silicon carbide tubular membrane tube is provided with a plurality of large through hole structures along the axial direction of the silicon carbide tubular membrane tube, the diameter of each large through hole structure is 8mm, and the aperture of each membrane tube is 150nm; and the cleaning assembly is connected to the silicon carbide membrane assembly and is used for cleaning the silicon carbide membrane assembly according to preset setting. The anaerobic biogas slurry treatment device has higher blockage resistance, adapts to treatment of anaerobic biogas slurry with high solid content and more organic fiber components, effectively relieves the problems of scaling and fiber winding blockage, and solves the problem of membrane strength through the thickening design of the distance between the membrane pipes.

Description

Technical Field

[0001] The present application relates to a novel biogas slurry membrane filtration device based on silicon carbide membrane, belonging to the technical field of high-concentration organic sewage treatment. Background Art

[0002] In China, the anaerobic fermentation biogas slurry of high-concentration organic wastewater is generally pretreated by the traditional process of "centrifugal pretreatment + two-stage air flotation". The pretreated effluent not only has a high SS (Suspended Solid), but also causes problems such as high energy consumption in the subsequent sewage treatment system, difficulty in resource utilization, and a large amount of membrane concentrate to be treated, which has become an important bottleneck restricting the high-quality development of high-concentration organic wastewater treatment technology. At present, using membrane filtration technology to pretreat biogas slurry is a new sewage treatment technology, and the existing anaerobic biogas slurry membrane treatment systems generally use polyvinylidene fluoride (PVDF) membrane materials, but there are problems such as poor oil resistance, intolerance to high temperature, easy aging, serious membrane fouling, frequent cleaning, and high system energy consumption in actual operation. In addition, the single-group layout of traditional membrane modules is mainly in the form of multiple membranes in series, which is prone to disadvantages such as uneven local flow velocity, large membrane pressure difference fluctuation, and strong filtration efficiency fluctuation. Moreover, the membrane pore size mostly concentrates in the range of 20 - 50 nm. Without obvious advantages in the effluent quality, the unit membrane flux is low, the membrane area is large, and the investment cost is high. The membrane tube uses a large through-hole structure with an 8 mm process for the first time at home and abroad. Compared with the common membrane tube diameters of 4 mm or even smaller in the current market, it has stronger anti-blocking performance, is suitable for the treatment of anaerobic biogas slurry with high solid content and more organic fiber components, effectively alleviates the problems of scaling and fiber winding blockage, and at the same time solves the problem of membrane strength through the thickening design of the membrane tube spacing. Summary of the Invention

[0003] The purpose of the present application is to provide a novel biogas slurry membrane filtration device based on silicon carbide membrane, which solves the technical difficulties such as blockage and corrosion in the treatment of kitchen waste biogas slurry in the prior art, and further promotes the conversion of kitchen waste into clean energy, achieving a win-win situation of environmental benefits and economic benefits.

[0004] To achieve the above purpose, the present application provides the following technical solutions: A novel biogas slurry membrane filtration device based on silicon carbide membrane, comprising: A silicon carbide membrane module, which is composed of four groups of membrane groups connected in parallel, and a shunt pipe and a collecting pipe are respectively connected to both ends of the four groups of membrane groups; Each group of membrane groups includes four silicon carbide tubular membrane tubes, the four silicon carbide tubular membrane tubes are connected in series, and each silicon carbide tubular membrane tube is provided with a plurality of large through-hole structures along its axial direction, the diameter of the large through-hole structure is 8 mm, and the pore diameter of the membrane tube is 150 nm; A cleaning component, which is connected to the silicon carbide membrane component and cleans the silicon carbide membrane component according to preset settings.

[0005] Preferably, the silicon carbide tubular membrane tube includes: A membrane shell, A first silicon carbide membrane filter element, and there are five of the first silicon carbide membrane filter elements. The five first silicon carbide membrane filter elements are filled in the center of the membrane shell, and a first water production gap is formed between each of the five first silicon carbide membrane filter elements; A second silicon carbide membrane filter element, and there are four of the second silicon carbide membrane filter elements. The four second silicon carbide membrane filter elements are symmetrically arranged in pairs on both sides of the first silicon carbide membrane filter element, and a second water production gap is formed between the second silicon carbide membrane filter element and the first silicon carbide membrane filter element. The second silicon carbide membrane filter element and the first silicon carbide membrane filter element are both filled in the membrane shell.

[0006] Preferably, the first silicon carbide membrane filter element is axially provided with a plurality of large through-hole structures and a plurality of first through-hole structures, and the second silicon carbide membrane filter element is axially provided with a plurality of large through-hole structures, a plurality of first through-hole structures, and a plurality of second through-hole structures, further increasing the filtration area without affecting the strength of the first silicon carbide membrane filter element and the second silicon carbide filter element.

[0007] Preferably, a water production branch pipe is connected to the membrane shell, and the water production branch pipe is connected to a water production main pipe. The water filtered by the first silicon carbide membrane filter element and the second silicon carbide membrane filter element converges from the first water production gap and the second water production gap to the membrane shell, then converges to the water production main pipe through the water production branch pipe, and is discharged from the water production port.

[0008] Preferably, a circulation pipe is connected between the shunt pipe and the collection pipe, and a circulation pump is installed on the circulation pipe. The circulation pump enables the biogas slurry to pass through the membrane filtration system multiple times to achieve multiple filtrations, improving the filtration efficiency. At the same time, it also has the functions of maintaining the system pressure and stabilizing the system flow rate.

[0009] Preferably, the cleaning component includes: a clean water flushing mechanism and a clean water backwashing mechanism. [[ID=2 (23)]]

[0010] Preferably, the clean water flushing mechanism includes: [[ID=2 (25)]] A clean water tank for storing clean water; [[ID=2 (27)]] A clean water pump connected to the clean water tank; [[ID=2 (29)]] An electric main valve for the cleaning pipeline, connected to the clean water pump, [[ID=2 (31)]] The shunt pipe is provided with a clean water inlet and a clean water return port. The clean water return port is communicated with the clean water tank, and the clean water inlet is communicated with the electric main valve for the cleaning pipeline; [[ID=2 (33)]] The circulation pump is connected to the circulation pipe, the circulation pipe is connected to the collecting pipe, and the collecting pipe is connected to the silicon carbide tubular membrane tube; The clean water flows out of the clean water tank through the cleaning pump and the electric main valve of the cleaning pipeline and enters the clean water inlet, and is then pressurized by the circulation pump and enters the collecting pipe through the circulation pipe, and is then distributed to the silicon carbide tubular membrane tube through the collecting pipe to flush the large through-hole structure, the first through-hole structure, and the second through-hole structure. The sewage after flushing is collected in the diversion pipe and then returns to the clean water tank from the clean water return port.

[0011] Preferably, the clean water backwash mechanism comprises: the clean water tank is connected to the clean water pump, the clean water pump is connected to the backwash water inlet valve, the backwash water inlet valve is connected to the backwash water inlet main pipe, the backwash water inlet main pipe is connected to the backwash branch pipe, and the backwash branch pipe is connected to the membrane housing; The clean water flows out of the clean water tank and is distributed to each backwash branch pipe after passing through the clean water pump, the backwash water inlet valve, and the backwash water inlet main pipe. The clean water enters the membrane housing and is continuously pressurized by the clean water pump. The clean water pressurizes the first silicon carbide membrane filter element and the second silicon carbide membrane filter element through the first water production gap and the second water production gap. The clean water passes through the first silicon carbide membrane filter element and the second silicon carbide membrane filter element and presses the pollutants together to the large through-hole structure, the first through-hole structure, and the second through-hole structure, and then converges to the diversion pipe and is discharged from the backwash drain port provided on the diversion pipe.

[0012] Preferably, the cleaning component further comprises a chemical cleaning mechanism, and the chemical cleaning restores the filtration performance of the membrane by dissolving or stripping off pollutants.

[0013] Preferably, it also includes a skid for installing the silicon carbide membrane assembly, the circulation pump, the diversion pipe, the circulation pipe, and the collecting pipe, so as to facilitate overall transportation and rapid installation.

[0014] The beneficial effects of this application are: 1. The core of this device uses silicon carbide (SiC) ceramic membrane material to replace traditional organic membranes. It has excellent properties such as oil resistance, high temperature resistance, acid and alkali resistance, antioxidant corrosion resistance and high mechanical strength. The operating cycle is significantly extended in high pollution load environments, the cleaning frequency is reduced, and the system stability is enhanced. The membrane pore size range of 100-200nm is selected to take into account high membrane flux and solid-liquid separation accuracy. While ensuring the water quality meets the standards, the membrane area and the initial investment of the system are reduced.

[0015] 2. This application adopts a "series + parallel" membrane arrangement structure: each set of equipment consists of four groups of membrane groups in parallel, and each group of membrane groups is equipped with four silicon carbide tubular membrane tubes in series. The overall arrangement direction is coaxial with the direction of the water inlet and circulation pump, which increases the flow rate, reduces the pressure loss, and significantly reduces the risk of membrane pollution.

[0016] 3. The first silicon carbide membrane filter element and the second silicon carbide membrane filter element of this application generally adopt a large through-hole structure with an 8 mm manufacturing process. In some areas, a first through-hole structure with a "raindrop shape" in cross-section and a second through-hole structure with a diameter of 4 mm are adopted to further improve the filling rate. Compared with the traditional membrane tube diameter of 4 mm or even smaller, this structure has better anti-blocking performance, is suitable for the treatment of anaerobic biogas slurry with high solid content and high organic fiber content, effectively alleviates the problems of scaling and fiber entanglement. At the same time, through the design of thickening the membrane tube spacing, the structural strength of the membrane module is significantly enhanced, and through the settings of the first water production gap and the second water production gap, the membrane flux and water production efficiency are further improved.

[0017] 4. This application adopts a skid-mounted design, which reduces the floor area of the device and enables rapid installation, deployment, and subsequent maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic three-dimensional structure of this application Figure I ; Figure 2 is a schematic three-dimensional structure of this application Figure II ; Figure 3 is a schematic front view structure diagram of this application; Figure 4 is a schematic cross-sectional structure diagram of the first silicon carbide membrane filter element and the second silicon carbide membrane filter element of this application; Figure 5 is a schematic overall connection relationship structure diagram of this application.

[0019] In the figure: 1, silicon carbide tubular membrane tube; 101, the first silicon carbide membrane filter element; 102, the second silicon carbide membrane filter element; 103, large through-hole structure; 104, the first through-hole structure; 105, the second through-hole structure; 106, the first water production gap; 107, the second water production gap; 2, shunt pipe; 201, biogas slurry inlet; 202, biogas slurry inlet valve; 203, clean water inlet; 204, clean water return port; 205, backwash drain port; 206; backwash drain port valve; 207, clean water return port valve; 3, collection pipe; 301, concentrated water outlet; 302, concentrated water outlet valve; 4, circulation pipe; 5, circulation pump; 6, backwash inlet valve; 7, backwash inlet main pipe; 8, backwash branch pipe; 9, clean water tank; 10, clean water pump; 11, cleaning pipeline electric main valve; 12, chemical cleaning tank; 13, chemical cleaning pump; 14, biogas slurry feed pump; 15, self-cleaning filter; 16, security filter; 17, feed outlet pipe manual main valve; 18, support frame; 19, circulation pump installation base; 20, water production port; 21, water production branch pipe; 22, water production main pipe; 23, exhaust valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] In order to easily understand the technical means, creative features, achieved objectives and effects of this application, the following further elaborates this application in conjunction with specific illustrations.

[0021] In this application, unless otherwise clearly specified and defined, terms such as "installation", "connection", "linkage", "fixation" and the like shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0022] In this application, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0023] The following disclosure provides many different embodiments or examples for implementing different structures of the embodiments of this application. To simplify the disclosure of the embodiments of this application, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit this application. In addition, the embodiments of this application may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the embodiments of this application provide examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0024] As Figures 1 - 5 shown, a novel biogas slurry membrane filtration device based on a silicon carbide membrane is elaborated in detail as follows: The silicon carbide membrane module is composed of four groups of membrane units connected in parallel. The two ends of the four groups of membrane units are respectively connected with a shunt pipe 2 and a collecting pipe 3. And membrane unit branch inlet valves are installed on the connecting pipes between the four groups of membrane units and the shunt pipe 2, and membrane unit branch outlet valves are installed on the connecting pipes between the four groups of membrane units and the collecting pipe 3; Each group of membrane units includes four silicon carbide tubular membrane tubes 1. The four silicon carbide tubular membrane tubes 1 are connected in series through a clamp sealing structure. Each silicon carbide tubular membrane tube 1 is provided with a plurality of large through-hole structures 103 along its axial direction. The inner diameter of the large through-hole structure 103 is 8 mm, so that the concentrated water can pass through quickly, and at the same time, it is suitable for the treatment of anaerobic biogas slurry with high solid content and high organic fiber content, effectively alleviating the problems of scaling and fiber entanglement. The filtration pore diameter of the silicon carbide tubular membrane tube 1 is selected within the range of 100-200 nm, taking into account both a relatively high membrane flux and solid-liquid separation accuracy, reducing the membrane area and the initial investment of the system while ensuring the effluent water quality meets the standard. The silicon carbide tubular membrane tube 1 includes: a membrane shell, and the membrane shell is of a tubular structure; Five first silicon carbide membrane filter elements 101 are provided. The five first silicon carbide membrane filter elements 101 are filled in the center of the membrane shell, and a first water production gap 106 is formed between the five first silicon carbide membrane filter elements 101; Four second silicon carbide membrane filter elements 102 are provided. The four second silicon carbide membrane filter elements 102 are symmetrically arranged in pairs on both sides of the first silicon carbide membrane filter element 101, and a second water production gap 107 is formed between the second silicon carbide membrane filter element 102 and the first silicon carbide membrane filter element 101. The second silicon carbide membrane filter element 102 and the first silicon carbide membrane filter element 101 are both filled in the membrane shell. Further, the first silicon carbide membrane filter element 101 is axially provided with a plurality of large through-hole structures 103 and a plurality of first through-hole structures 104, and the second silicon carbide membrane filter element 102 is axially provided with a plurality of large through-hole structures 103, a plurality of first through-hole structures 104 and a plurality of second through-hole structures 105. The first through-hole structure 104 adopts a through-hole structure with a "raindrop shape" in cross-section and has a variety of different sizes of "raindrop shapes". The second through-hole structure 105 has an inner diameter of 4 mm, further increasing the filtration area without affecting the strength of the first silicon carbide membrane filter element 101 and the second silicon carbide filter element. The first silicon carbide membrane filter element 101 and the second silicon carbide filter element are both made of silicon carbide (SiC) ceramic membrane materials, having excellent properties such as oil resistance, high temperature resistance, acid and alkali resistance, antioxidant corrosion resistance and high mechanical strength. The operation cycle is significantly extended in a high pollution load environment, the cleaning frequency is reduced, and the system stability is enhanced.When the target biogas slurry passes through the first silicon carbide membrane filter element 101 and the second silicon carbide membrane filter element 102, the concentrated water converges from the large through-hole structure 103, the first through-hole structure 104, and the second through-hole structure 105 to the collecting pipe 3 and then returns to the biogas slurry storage tank in the pretreatment stage through the concentrated water outlet 301 provided on the collecting pipe 3. A concentrated water outlet valve 302 is installed at the concentrated water outlet 301; the filtered water converges from the first water production gap 106 and the second water production gap 107 to the membrane housing. A water production branch pipe is connected to the membrane housing. The water production branch pipe is connected to the water production main pipe. The water produced by the filtration of the first silicon carbide membrane filter element 101 and the second silicon carbide membrane filter element 102 converges from the first water production gap 106 and the second water production gap 107 to the membrane housing and then converges to the water production main pipe through the water production branch pipe and is discharged from the water production outlet. It should be noted that a water production butterfly valve is installed at the water production outlet.

[0025] As a further preferred embodiment, a circulation pipe 4 is connected between the shunt pipe 2 and the collecting pipe 3. An exhaust valve 23 is installed on the circulation pipe 4, and a circulation pump 5 is installed on the circulation pipe 4 (the circulation pump 5 is a variable-frequency pump with adjustable flow rate, and the inlet water flow rate is ≥ 4 m / s to ensure cross-flow filtration, which can slow down membrane fouling to the greatest extent. At the same time, the rotational speed of the variable-frequency pump is adjustable to save power consumption to the greatest extent). This setting has many benefits, which are elaborated in detail below: I. Improve water quality and treatment effect: 1. Homogenize water quality: The water quality components of kitchen waste biogas slurry are complex and unstable. The water quality parameters (such as COD, BOD, ammonia nitrogen, suspended solid concentration, etc.) of biogas slurry from different time periods and different sources may vary greatly in the sewage main pipe. By connecting the shunt pipe 2 and the collecting pipe 3 with the circulation pump 5, the biogas slurry can circulate in the system, enabling the biogas slurry with different water qualities to be fully mixed, thus homogenizing the overall water quality and avoiding the impact on the subsequent treatment process caused by excessive local water quality fluctuations. 2. Improve biodegradability: Circulating flow can increase the contact opportunities between microorganisms and pollutants in the biogas slurry, promoting the decomposition and transformation of organic matter by microorganisms. Some refractory organic matters will be gradually degraded into small-molecule substances by microorganisms during the circulation process, improving the biodegradability of the biogas slurry and creating more favorable conditions for the subsequent biological treatment process. II. Stabilize system operation: 1. Buffer the impact of water quality and quantity: The generation amount of kitchen waste is uncertain, which will lead to large fluctuations in the production and water quality of biogas slurry. When a large amount of high-concentration or low-concentration biogas slurry suddenly enters the collecting pipe 3, the circulation pump 5 can quickly mix this part of the biogas slurry with the liquid in the shunt pipe 2, playing a buffering role and avoiding the overload operation of the treatment system or the decline of the treatment effect due to the sudden change of water quality and quantity. 2. Maintain the stability of system pressure and flow rate: The circulation pump 5 can adjust the flow rate and pressure according to the actual needs of the system to ensure that the liquid in the collecting pipe 3 and the shunt pipe 2 maintains a stable flow state. Stable pressure and flow rate are beneficial to the normal operation of various treatment equipment (such as pumps, valves, reactors, etc.), reduce equipment wear and failure rates, and extend the service life of equipment.

[0026] A cleaning component, connected to the silicon carbide membrane component, and used to clean the silicon carbide membrane component according to pre - settings. The cleaning component includes: a fresh water flushing mechanism and a fresh water back - flushing mechanism. Specifically, the fresh water flushing mechanism includes: a fresh water tank 9 for storing fresh water; a fresh water pump 10 connected to the fresh water tank 9; a cleaning pipeline electric main valve 11 connected to the fresh water pump 10, a shunt pipe 2 provided with a fresh water inlet 203 and a fresh water return port 204, the fresh water return port 204 is communicated with the fresh water tank 9, and the fresh water inlet 203 is communicated with the cleaning pipeline electric main valve 11; the circulation pump 5 is connected to the circulation pipe 4, the circulation pipe 4 is connected to the collecting pipe 3, and the collecting pipe 3 is connected to the silicon carbide tubular membrane tube 1; The fresh water flushing path is as follows: Fresh water exits from the fresh water tank 9, passes through the cleaning pump and the cleaning pipeline electric main valve 11, enters from the fresh water inlet 203 of the shunt pipe 2, is pressurized by the circulation pump 5 (it should be noted that the circulation pump 5 uses a variable - frequency circulation pump 5 that can rotate forward and backward on the market, such as the SXF - 25 of Shanghai Cangmao Industry Co., Ltd.) and enters the collecting pipe 3 through the circulation pipe 4, and then is distributed to the silicon carbide tubular membrane tube 1 through the collecting pipe 3 to flush the large through - hole structure 103, the first through - hole structure 104, and the second through - hole structure 105. The flushed water converges to the shunt pipe 2 and then returns to the fresh water tank 9 from the fresh water return port 204. It should be noted that during the flushing process of the fresh water cleaning and flushing mechanism, the biogas inlet valve 202, the concentrated water port valve 302, and the back - flushing drain port valve 206 on the biogas inlet 201 are in the closed state.

[0027] The clean water backwashing mechanism includes the following: The clean water tank 9 is connected to the clean water pump 10, the clean water pump 10 is connected to the backwashing water inlet valve 6, the backwashing water inlet valve 6 is connected to the backwashing water inlet main pipe 7, the backwashing water inlet main pipe 7 is connected to the backwashing water branch pipes 8, and check valves are installed on the backwashing water branch pipes 8. The check valves ensure that the filtered water during the water production process converges to the water production main pipe and will not be lost from the backwashing water inlet main pipe 7; the backwashing water branch pipes 8 are connected to the membrane housing; the clean water backwashing path is as follows: Clean water exits from the clean water tank 9, passes through the clean water pump 10 and the backwashing water inlet valve 6, enters the backwashing water inlet main pipe 7, and is then distributed to each backwashing water branch pipe 8. The clean water enters the membrane housing. Under the continuous pressurization of the clean water pump 10, the clean water pressurizes the first silicon carbide membrane filter element 101 and the second silicon carbide membrane filter element 102 through the first water production gap 106 and the second water production gap 107. The clean water passes through the first silicon carbide membrane filter element 101 and the second silicon carbide membrane filter element 102 and presses the pollutants together to the large through-hole structure 103, the first through-hole structure 104, and the second through-hole structure 105, and then converges to the shunt pipe 2 and is discharged from the backwashing drain port 205 provided on the shunt pipe 2. A backwashing drain port valve 206 is installed at the backwashing drain port 205. It should be noted that when the clean water backwashing mechanism is working, the membrane group branch outlet valve, the clean water return port valve 207, the biogas slurry inlet valve 202, and the clean water inlet valve installed on the clean water inlet 203 are all in the closed state.

[0028] As a preferred embodiment, the cleaning assembly further includes a chemical cleaning mechanism. Chemical cleaning restores the filtration performance of the membrane by dissolving or stripping pollutants. The difference between the chemical cleaning mechanism and the clean water flushing mechanism and the clean water backwashing mechanism is that the chemical cleaning mechanism is connected to the chemical cleaning pump 13 and the chemical cleaning tank 12. Acid cleaning solution, alkali cleaning solution, or oxidant solution is configured in the chemical cleaning tank 12 according to different requirements. And the cleaning frequency of the chemical cleaning mechanism is generally once a month, while the clean water cleaning is generally once a day.

[0029] The skid base is used to install the silicon carbide membrane module, the circulation pump 5, the shunt pipe 2, the circulation pipe 4, the collecting pipe 3, the water production pipe, the backwashing pipe, etc. And two sets of the above-mentioned mechanisms are installed on the skid base to facilitate overall handling and rapid installation, and at the same time greatly reduce the floor area. The skid base is composed of two support frames 18 and a circulation pump installation base 19.

[0030] Principle: Biogas slurry enters the self-cleaning filter 15 and the security filter 16 in the pretreatment stage from the biogas slurry temporary storage tank via the biogas slurry feed pump 14. After pretreatment, it passes through the manual main valve 17 of the feed outlet water pipe and enters the shunt pipe 2 from the biogas slurry inlet 201. The shunt pipe 2 distributes the biogas slurry entering the shunt pipe 2 to the four groups of membrane modules connected thereto. The biogas slurry enters the four series-connected silicon carbide tubular membrane tubes 1. When the biogas slurry passes through the first silicon carbide membrane filter element 101 and the second silicon carbide membrane filter element 102, the filtered water converges to the membrane housing from the first water production gap 106 and the second water production gap 107, and then is collected to the water production main pipe 22 from the water production branch pipe 21 and discharged from the water production outlet 20. The unfiltered concentrated water converges to the collection pipe 3 from the large through-hole structure 103, the first through-hole structure 104, and the second through-hole structure 105 and then returns to the biogas slurry temporary storage tank in the pretreatment stage from the concentrated water outlet 301. During this process, the circulation pump 5 is also started to pump a part of the concentrated water in the collection pipe 3 to the shunt pipe 2, mix it with the biogas slurry coming from the pretreatment stage in the shunt pipe 2, and then enter the four groups of modules for filtration. It should be noted that the pipelines in the cleaning assembly are all in a closed state during this process.

[0031] In a preferred embodiment of the present invention, an inorganic membrane module made of silicon carbide is selected as the core filtration unit for biogas slurry treatment. The silicon carbide membrane used has excellent anti-pollution performance, chemical corrosion resistance, and relatively high mechanical strength. The membrane pore size is controlled within the range of 100-200 nm to balance the membrane flux and interception efficiency.

[0032] In this embodiment, the typical biogas slurry raw water is filtered through an organic membrane (traditional PVDF material) and the silicon carbide membrane respectively, and the water quality of the obtained effluent is compared as follows (statistically based on the average value):

[0033] Parameter Index Organic Membrane Effluent Silicon Carbide Membrane Effluent pH 8.08 8.10 SCOD (mg / L) 2573 2335 VFAs (mg / L) 299 309 TN (mg / L) 2655 2658 <![CDATA[NH3-N (mg / L)]]> 2516 2555 TP (mg / L) 19.6 20.1 SS (g / L) 0 0 <![CDATA[Hardness (mg / L, calculated as CaCO3)]]> 275 269 Colority 100 100

[0034] As can be seen from the above data, although the silicon carbide membrane adopts a larger pore size design, its effluent water quality is basically the same as that of the organic membrane in terms of main indicators such as pH, SCOD, volatile fatty acids (VFAs), total nitrogen (TN), ammonia nitrogen (NH3-N), total phosphorus (TP), suspended solids (SS), hardness, and chromaticity, with no significant difference, and it maintains good solid removal efficiency and pollutant removal effect.

[0035] Table 2 Comparison of comprehensive performance indicators between silicon carbide membrane and traditional PVDF membrane Index Traditional PVDF Membrane Silicon Carbide Membrane of the Present Invention Service Life (years) 1-2 ≥5 Membrane Pore Size (nm) 20~50 100~200 <![CDATA[Unit membrane flux (L / (m 2 ·h))]]> 15 ≥30 High Temperature Resistance (°C) ≤40 ≥100 Chemical Membrane Washing Cycle (d) ≤30 45 Backwashing Tolerance Poor Excellent In addition, due to the stronger anti-pollution ability and high-intensity backwashing characteristics of the silicon carbide membrane, it shows more stable flux and lower cleaning frequency during long-term operation, effectively extending the membrane life and reducing the operation cost. Therefore, the application of this silicon carbide membrane in biogas slurry treatment has excellent practical value and promotion prospects.

[0036] The foregoing has shown and described the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments, and without departing from the spirit and scope of the present application, the present application will have various changes and improvements, and these changes and improvements fall within the scope of the present application claimed. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. A novel biogas slurry membrane filtration device based on a silicon carbide membrane, characterized in that, Including: A silicon carbide membrane module, which is composed of four groups of membrane units connected in parallel. Shunt pipes and collecting pipes are respectively connected to both ends of the four groups of membrane units; Each group of membrane units includes four silicon carbide tubular membrane pipes, and the four silicon carbide tubular membrane pipes are connected in series. A plurality of large through-hole structures are arranged along the axial direction of each silicon carbide tubular membrane pipe, the diameter of the large through-hole structure is 8 mm, and the filtration pore diameter of the silicon carbide tubular membrane pipe is 150 nm; A cleaning assembly, which is connected to the silicon carbide membrane module and cleans the silicon carbide membrane module according to pre-settings.

2. The novel biogas slurry membrane filtration device based on a silicon carbide membrane according to claim 1, wherein The silicon carbide tubular membrane pipe includes: A membrane shell, Five first silicon carbide membrane filter elements, the five first silicon carbide membrane filter elements are filled in the center of the membrane shell, and a first water production gap is formed between the five first silicon carbide membrane filter elements; Four second silicon carbide membrane filter elements, the four second silicon carbide membrane filter elements are symmetrically arranged in pairs on both sides of the first silicon carbide membrane filter element, and a second water production gap is formed between the second silicon carbide membrane filter element and the first silicon carbide membrane filter element. The second silicon carbide membrane filter element and the first silicon carbide membrane filter element are both filled in the membrane shell.

3. The novel biogas slurry membrane filtration device based on a silicon carbide membrane according to claim 2, wherein: A plurality of large through-hole structures and a plurality of first through-hole structures are axially arranged on the first silicon carbide membrane filter element, and a plurality of large through-hole structures, a plurality of first through-hole structures and a plurality of second through-hole structures are axially arranged on the second silicon carbide membrane filter element, further increasing the filtration area without affecting the strength of the first silicon carbide membrane filter element and the second silicon carbide filter element.

4. A novel biogas slurry membrane filtration device based on a silicon carbide membrane according to claim 3, characterized in that: A water production branch pipe is communicated with the membrane shell, the water production branch pipe is connected to a water production main pipe, and the water filtered by the first silicon carbide membrane filter element and the second silicon carbide membrane filter element converges from the first water production gap and the second water production gap to the membrane shell, then converges to the water production main pipe through the water production branch pipe, and is discharged from the water production port.

5. The novel biogas slurry membrane filtration device based on silicon carbide membrane according to claim 2 or 4, characterized in that: A circulation pipe is communicated between the shunt pipe and the collecting pipe, and a circulation pump is installed on the circulation pipe. The circulation pump enables the biogas slurry to pass through the membrane filtration system multiple times to achieve multiple filtrations, improving the filtration efficiency, and at the same time, it also has the functions of maintaining the system pressure and stabilizing the system flow rate.

6. A novel biogas slurry membrane filtration device based on a silicon carbide membrane according to claim 5, characterized in that, The cleaning assembly includes: a clean water flushing mechanism and a clean water backwashing mechanism.

7. A novel biogas slurry membrane filtration device based on a silicon carbide membrane according to claim 6, characterized in that: The clean water flushing mechanism includes: A clean water tank for storing clean water; A clean water pump connected to the clean water tank; A cleaning pipeline electric main valve connected to the clean water pump, The shunt pipe is provided with a clean water inlet and a clean water return port. The clean water return port is communicated with the clean water tank, and the clean water inlet is communicated with the cleaning pipeline electric main valve; The circulation pump is connected to the circulation pipe, the circulation pipe is connected to the collecting pipe, and the collecting pipe is connected to the silicon carbide tubular membrane pipe; Clear water flows out from the clear water tank, passes through the cleaning pump and the main electric valve of the cleaning pipeline, and enters from the clear water inlet. Then, it is pressurized by the circulation pump and enters the collecting pipe through the circulation pipe. After that, it is distributed to the silicon carbide tubular membrane pipes through the collecting pipe to wash the large through-hole structure, the first through-hole structure, and the second through-hole structure. The sewage after washing converges to the shunt pipe and then returns to the clear water tank from the clear water return port.

8. A novel biogas slurry membrane filtration device based on a silicon carbide membrane according to claim 7, characterized in that: The clear water backwashing mechanism includes: the clear water tank is connected to the clear water pump, the clear water pump is connected to the backwashing water inlet valve, the backwashing water inlet valve is connected to the main backwashing water inlet pipe, the main backwashing water inlet pipe is connected to the backwashing branch pipes, and the backwashing branch pipes are connected to the membrane housing; Clear water flows out from the clear water tank, passes through the clear water pump, the backwashing water inlet valve, and the main backwashing water inlet pipe, and then is distributed to each backwashing branch pipe. The clear water enters the membrane housing. Under the continuous pressurization of the clear water pump, the clear water pressurizes the first silicon carbide membrane filter element and the second silicon carbide membrane filter element through the first water production gap and the second water production gap. The clear water passes through the first silicon carbide membrane filter element and the second silicon carbide membrane filter element and presses the pollutants together to the large through-hole structure, the first through-hole structure, and the second through-hole structure. Then, it converges to the shunt pipe and is discharged from the backwashing drain port provided on the shunt pipe.

9. A novel biogas slurry membrane filtration device based on a silicon carbide membrane according to claim 8, characterized in that: The cleaning assembly further includes a chemical cleaning mechanism. Chemical cleaning restores the filtering performance of the membrane by dissolving or stripping pollutants.

10. A novel biogas slurry membrane filtration device based on a silicon carbide membrane according to claim 9, characterized in that: It further includes a skid base for installing the silicon carbide membrane assembly, the circulation pump, the shunt pipe, the circulation pipe, and the collecting pipe, facilitating overall handling and rapid installation.

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