External tubular anaerobic MBR (Membrane Bioreactor) membrane device, membrane component and wastewater treatment method

Abstract

The invention discloses an external tubular anaerobic MBR (Membrane Bioreactor) membrane device, a membrane assembly and a wastewater treatment method. The device comprises a plurality of parallel membrane assemblies, wherein a plurality of serial membrane elements are arranged in the membrane assemblies; the forward water distributor is communicated with the water inlet end of each membrane component; the reverse water distributor is communicated with the concentrated water end of each membrane component; a produced water collection system; a concentrated water return pipe; the flow direction switching system comprises a valve group, and the valve group can be switched to a first communication state, so that the water inlet pipeline is communicated with the forward water distributor, and the concentrated water return pipe is communicated with the reverse water distributor; or the second communication state is switched, so that the water inlet pipeline is communicated with the reverse water distributor, and the concentrated water return pipe is communicated with the forward water distributor. The problem of pressure attenuation is solved through membrane shell parallel connection and membrane element series connection, and membrane pollution is delayed through bidirectional operation. The membrane pollution rate is reduced by more than 50%, the operation cycle is prolonged to 30-45 days, and the method is suitable for high-concentration organic wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to an external tubular anaerobic MBR membrane device, membrane module, and wastewater treatment method. Background Technology

[0002] With increasingly stringent standards for industrial wastewater and domestic sewage discharge, there is an urgent need for efficient and stable wastewater treatment technologies. Anaerobic membrane bioreactors (AnMBRs) combine the advantages of efficient pollutant removal and low sludge production from anaerobic biological treatment with the excellent solid-liquid separation capabilities of membrane separation technology, demonstrating great potential in the field of water resource recovery. Among them, tubular membranes, due to their wide flow channels and strong resistance to fouling, are particularly suitable for treating anaerobic effluent with high suspended solids and high organic matter concentrations.

[0003] However, existing external tubular anaerobic MBR devices have many drawbacks, limiting their treatment efficiency, stability, and scalable application. Patent searches reveal that similar technologies, such as patent CN215559728U ("An Anaerobic MBR Treatment System") and patent CN218465614U ("An Anaerobic MBR Membrane Bioreactor for Kitchen Waste Slurry"), typically employ a core design of "membrane modules in series + membrane elements (membrane tubes) in parallel." This structure presents the following main problems:

[0004] Uneven pressure distribution and limited flux: Parallel connection of membrane elements leads to uneven fluid distribution and insufficient shear force on the membrane surface; while series connection of membrane modules leads to pressure loss along the process, pressure decay of the end membrane module, and low overall membrane flux, usually maintained at 15-35 L / (m²·h).

[0005] Severe membrane fouling and incomplete cleaning: With a fixed one-way water inlet and one-way cleaning mode, pollutants are easily attached and accumulated on the membrane surface and inside the membrane pores. Conventional cleaning is difficult to remove them effectively, resulting in a fast membrane fouling rate and a short operating cycle (usually only 7-15 days), requiring frequent shutdowns for cleaning.

[0006] Poor scalability: The number of membrane modules connected in series is limited (generally no more than 6). If the processing scale is to be expanded, multiple units can only be connected in parallel, resulting in a large system footprint, complex piping, increased energy consumption, and the inability to solve the pressure decay problem within a single unit.

[0007] Conservative operating pressure: Traditional equipment is often designed with operating pressure below 5 kg / cm², which fails to fully utilize the potential of increasing operating pressure to improve membrane flux, and the membrane separation performance is not fully realized.

[0008] Therefore, there is an urgent need to develop a new type of tubular anaerobic MBR membrane device that can solve the above problems and achieve high efficiency, stability, easy expansion and strong anti-fouling ability. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide an external tubular anaerobic MBR membrane device with membrane elements connected in series and membrane modules connected in parallel, and its application method. This device, through its innovative structural layout and operating mode, aims to significantly improve membrane flux and treatment capacity, effectively control membrane fouling, extend operating cycles, and reduce operating energy consumption.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention discloses an external tubular anaerobic MBR membrane device for treating high-suspended-solids organic wastewater, comprising:

[0012] The inlet pipeline is used to transport the anaerobic effluent to be treated;

[0013] Multiple membrane modules are connected in parallel to the water inlet pipe. Each membrane module includes a membrane shell and at least two membrane elements disposed inside the membrane shell. The at least two membrane elements are connected end to end in series within the membrane shell to form an independent series flow channel.

[0014] The forward water distributor is connected to the inlet of each membrane module;

[0015] The reverse water distributor is connected to the concentrate end of each membrane module;

[0016] A permeate collection system, connected to the permeate end of each membrane module, is used to collect permeate;

[0017] A concentrate return pipe is connected to the concentrate end of each membrane module;

[0018] A flow direction switching system, including a valve assembly configured to selectively switch to:

[0019] In the first connected state, the inlet pipe is connected to the forward water distributor, and the concentrate return pipe is connected to the reverse water distributor; and...

[0020] In the second connection state, the water inlet pipe is connected to the reverse water distributor, and the concentrated water return pipe is connected to the forward water distributor.

[0021] As a further preferred embodiment of the above technical solution, the valve assembly includes:

[0022] A positive inlet valve has its inlet connected to the inlet pipe and its outlet connected to the inlet end of the membrane module;

[0023] A reverse feed valve, the inlet of which is connected to the feed line and the outlet of which is connected to the concentrate end of the membrane module;

[0024] A forward concentrate valve has its inlet connected to the concentrate end of the membrane module and its outlet connected to the concentrate return pipe.

[0025] A reverse concentrate valve has its inlet connected to the inlet of the membrane module and its outlet connected to the concentrate return pipe.

[0026] The first connected state is achieved by opening the forward inlet valve and the forward concentrate valve, and closing the reverse inlet valve and the reverse concentrate valve; the second connected state is achieved by opening the reverse inlet valve and the reverse concentrate valve, and closing the forward inlet valve and the forward concentrate valve.

[0027] As a further preferred embodiment of the above technical solution, the water inlet pipeline includes a main water inlet pipe and water inlet branch pipes connected to each membrane module;

[0028] The concentrate return pipe is connected to the concentrate end of each membrane module through multiple concentrate branch pipes.

[0029] As a further preferred embodiment of the above technical solution, the membrane housing is made of corrosion-resistant metal or plastic; the device is configured to operate stably under an operating pressure of 3~10 kg / cm².

[0030] As a further preferred embodiment of the above technical solution, a second water pump is installed on the water inlet pipe; it also includes a pressure protection device, which comprises a pressure relief valve and a pressure sensor, wherein,

[0031] The pressure relief valve is installed on the outlet pipe of the second water pump or the inlet main pipe of the membrane module;

[0032] The pressure sensor is installed on the outlet pipe of the second water pump, the inlet end of the membrane module, or the product water collection system, and is communicatively connected to the control system.

[0033] As a further preferred embodiment of the above technical solution, a chemical cleaning / rinsing assembly is also included, comprising: a cleaning fluid storage tank, a third water pump, and a cleaning control valve, wherein the inlet of the third water pump is connected to the cleaning fluid storage tank, and the outlet of the third water pump is connected to the downstream outlet of the second water pump in the water inlet pipeline through the cleaning control valve.

[0034] As a further preferred embodiment of the above technical solution, the forward and reverse water distributors have the same structure and are configured to evenly distribute fluid to each branch pipe connected to them. Both include a valve drive mechanism, a valve housing, and a valve plate.

[0035] The valve housing has several through short pipe joints on opposite outer walls. A valve plate is provided between the through short pipe joints. Several valve plate holes are arranged on the valve plate. The valve plate holes are through holes and are arranged corresponding to the short pipe joints.

[0036] The valve drive mechanism is located outside the valve body, and the power output end of the valve drive mechanism is connected to the valve plate. The valve plate is driven to slide back and forth inside the valve body by the valve drive mechanism, so that the through short pipe joint is either connected or disconnected.

[0037] Secondly, the present invention also discloses a membrane assembly for the external tubular anaerobic MBR membrane device, comprising a membrane shell and at least two membrane elements disposed inside the membrane shell, wherein the at least two membrane elements are connected end to end in series via a high-strength sealing joint.

[0038] The high-strength sealing joint is located at both ends of the membrane module and is fixedly connected to the membrane shell by flange bolts or a mortise bolt. A sealing gasket is set between the high-strength sealing joint and the membrane module to ensure the sealing between the two. The high-strength sealing joint is equipped with multiple elbow connecting pipes and one or more membrane module inlet and outlet ends according to the number of membrane elements in the membrane module.

[0039] Thirdly, the present invention discloses a wastewater treatment method using the aforementioned external tubular anaerobic MBR membrane device, wherein the device further includes a permeate discharge valve and a permeate discharge pipe installed on the permeate pipe, and a concentrate return control valve and a concentrate return anaerobic control valve installed on the concentrate return pipe, the method comprising:

[0040] Forward operation mode: The flow direction switching system is switched to the first connected state. The pressurized wastewater enters each membrane module through the inlet pipe and the forward distributor, and flows through the membrane elements in series in sequence. The permeate is discharged through the permeate collection system. The concentrate flows out from the concentrate end of the membrane module through the reverse distributor and the concentrate return pipe, part of which flows back to the inlet pipe inlet and part of which flows back to the front-end anaerobic reactor.

[0041] When the flow direction switching system is switched to the second connected state, the pressurized wastewater enters from the concentrate end of the membrane module through the inlet pipe and the reverse distributor, flows in the reverse direction through the series-connected membrane elements, and flows out from the inlet end of the membrane module through the forward distributor and the concentrate return pipe.

[0042] Furthermore, it also includes forward and / or reverse chemical cleaning / rinsing modes:

[0043] Close the permeate discharge valve, concentrate return control valve and concentrate return anaerobic control valve, start the third water pump, and open the cleaning control valve and permeate return control valve.

[0044] Forward chemical cleaning: The flow direction switching system is switched to the first connected state, and the chemical cleaning solution flows forward through the membrane elements in each membrane module. The permeate and concentrate are both returned to the cleaning solution storage tank.

[0045] Reverse chemical cleaning: The flow direction switching system is switched to the second connected state, and the chemical cleaning solution flows in reverse through the membrane elements in each membrane module. The permeate and concentrate are both returned to the cleaning solution storage tank.

[0046] Beneficial effects:

[0047] First, the present invention provides an external tubular anaerobic MBR membrane device, which adopts a "parallel membrane shell + series membrane element" design: the series connection of membrane elements in the same membrane shell allows the fluid to flow through each membrane element in sequence, and the pressure is concentrated on the membrane surface, avoiding the pressure dispersion problem caused by parallel connection; the parallel operation of multiple membrane shells can flexibly increase or decrease the number of membrane shells without increasing the number of series stages, and completely solves the problems of pressure attenuation and land occupation during large-scale expansion.

[0048] Secondly, this invention features a flow direction switching function between the inlet and concentrate ends, which periodically changes the flow direction of the fluid within the membrane tube, disrupting the directional adhesion pattern of pollutants. Simultaneously, it incorporates a chemical cleaning / rinsing flow direction switching function, allowing the chemical cleaning / rinsing solution to flow bidirectionally through the membrane element. This not only flushes both sides of the membrane surface but also penetrates the membrane pores in the reverse direction, removing deeply attached pollutants. The synergistic effect of bidirectional operation and bidirectional cleaning reduces the membrane fouling rate to 0.005-0.01 MPa / d, a reduction of over 50% compared to existing technologies. The operating cycle is extended to 30-45 days, 2-3 times that of traditional devices, significantly reducing the frequency of downtime for cleaning and improving treatment efficiency.

[0049] Third, the parallel layout of the membrane housing in this invention reduces the number of multi-stage series pipeline connections, uneven pressure distribution, and the significantly lower water flux or water production of membrane modules at the end of the series compared to those at the beginning; the series connection of membrane elements ensures uniform flux distribution, avoids local overload damage, and extends the service life of the membrane elements.

[0050] Fourth, the optimized pressure-resistant structure of this invention enables the system to operate safely and stably under higher pressures, fully releasing the membrane separation potential, especially suitable for treating recalcitrant wastewater with high suspended solids and high COD. Operating at pressures above 5 kg fully utilizes the membrane separation potential, reducing energy consumption per unit of produced water by more than 40% compared to existing technologies. The extended operating cycle reduces the consumption of cleaning agents and water resources. Furthermore, the series-connected sealed connection of membrane elements and the modular design of the parallel membrane housing reduce maintenance difficulty and equipment repair costs, resulting in long-term maintenance cost savings of more than 40%.

[0051] Fifth, this invention is equipped with a pressure protection device to ensure stable operation of the system under high pressure of 3-10 kg; the series connection of membrane elements concentrates the pressure on the membrane surface, avoiding pressure loss in parallel layouts, and increasing pressure utilization efficiency to over 90% (compared to only 60%-70% in existing technologies). The combination of high-pressure drive and efficient pressure utilization completely breaks through the flux limit of traditional technologies. Even when treating high-viscosity, high-suspended-solids wastewater, it can still maintain a stable flux, making it applicable to a wider range of scenarios and solving the problem of insufficient stability in high-load wastewater treatment of existing technologies.

[0052] Sixth, the forward and reverse water distributor structures of this invention enable a single valve plate to control multiple external pipes. The valve plate has several through-holes arranged in a row, corresponding to short pipe joints. Only one drive mechanism is needed to simultaneously control the opening and closing of multiple inlets and outlets in the valve. Compared to existing multi-drive valves, this reduces operating energy consumption and lowers operating costs. Since the external pipes are connected to the short pipe joints on the valve body, the forward and reverse water distributors of this invention can flexibly increase or decrease the number of connected external pipes based on the number of connected short pipe joints, thus facilitating practical production applications. Furthermore, the forward and reverse water distributor structures of this invention are detachable, allowing for easy on-site replacement of parts in case of malfunction, which is beneficial for maintenance and repair of the device. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the process flow of the external tubular anaerobic MBR membrane device of the present invention.

[0054] Wherein, 1 is the anaerobic effluent pipe; 2 is the inlet tank; 3 is the first water pump; 4 is the second water pump; 5 is the membrane module; 6 is the forward inlet valve; 7 is the reverse inlet valve; 8 is the reverse concentrate valve; 9 is the forward concentrate valve; 10-1 is the forward distributor; 10-2 is the reverse distributor; 11 is the product water pipe; 12-1 is the inlet branch pipe; 12-2 is the concentrate branch pipe; 13 is the concentrate return pipe; 14 is the concentrate return anaerobic pipe; 15 is the concentrate return control valve; 16 is the concentrate return anaerobic control valve; 17 is the cleaning solution storage tank; 18 is the third water pump; 19 is the cleaning control valve; 20 is the product water return control valve; 21 is the product water discharge valve; 22 is the product water discharge pipe; 23 is the chemical cleaning / rinsing return pipe.

[0055] Figure 2 This is a schematic diagram of a single membrane module;

[0056] Figure 3 Diagram showing the connection between a high-strength sealing joint and a membrane module. Figure 1 ;

[0057] Among them, 24 are high-strength sealing joints;

[0058] Figure 4 Diagram showing the connection between a high-strength sealing joint and a membrane module. Figure 2 ;

[0059] Among them, 26 is the elbow connecting pipe; 27 is the inlet end of the membrane module; and 28 is the outlet end of the membrane module.

[0060] Figure 5 This is a schematic diagram of a sealing gasket;

[0061] Among them, 25 sealing gaskets;

[0062] Figure 6 This is a schematic diagram of the forward water distributor and the reverse water distributor of the present invention;

[0063] Wherein, 101 is the valve drive mechanism; 102 is the frame support; 103 is the coupling; 104 is the connecting shaft; 105 is the mechanical seal; 106 is the upper cover plate; 107 is the cover plate connecting bolt; 108 is the valve body; 109 is the valve plate; 1010 is the valve plate hole;

[0064] Figure 7 for Figure 6 Side view;

[0065] Among them, 1011 is sealing rubber; 1012 is short pipe joint; 1013 is valve shell bolt; 1014 is valve body base plate;

[0066] Figure 8 This is a perspective view of the forward water distributor and the reverse water distributor of the present invention. Detailed Implementation

[0067] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0068] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0069] like Figure 1As shown, the present invention provides an external tubular anaerobic MBR membrane device, which mainly includes an inlet pipe, multiple parallel membrane modules 5, a permeate collection system, a concentrate return pipe 13, a flow direction switching system, a cleaning system, and a pressure protection device (not shown separately in the figure).

[0070] The anaerobic effluent to be treated enters the anaerobic MBR feed tank 2 through the anaerobic effluent pipe 1. The tank is equipped with a level gauge (not shown) and is interlocked with the first water pump 3 to control the level. The effluent from the first water pump 3 is mixed with the return concentrate from the concentrate return pipe 13 and then pressurized and transported to the membrane system by the second water pump 4.

[0071] Regarding parallel and series structures: Multiple membrane modules 5 are connected to the system in parallel through inlet branch pipe 12-1 and concentrate branch pipe 12-2.

[0072] like Figure 2 As shown, each membrane module 5 contains multiple membrane elements, which are connected end-to-end in series within the membrane housing via high-strength sealing joints, and fluid flows sequentially through each membrane element. This parallel membrane housing + series membrane element layout is one of the core innovations of this invention.

[0073] Regarding the flow direction switching system: This system enables the device to switch between a first connected state (forward operation) and a second connected state (reverse operation). For example... Figure 1 As shown in the figure, as a specific embodiment of the present invention, the flow direction switching system includes a valve group, which specifically consists of a forward inlet valve 6 and a reverse inlet valve 7; and a concentrate valve group, which includes a forward concentrate valve 9 and a reverse concentrate valve 8.

[0074] In terms of pipeline connections, the inlet ends of multiple membrane modules 5 are connected to the forward water distributor 10-1 through the inlet branch pipe 12-1, and the concentrate ends of multiple membrane modules 5 are connected to the reverse water distributor 10-2 through the concentrate branch pipe 12-2.

[0075] The connection relationship of each valve in the valve group is as follows:

[0076] The forward inlet valve 6 is connected between the inlet pipe and the forward water distributor 10-1;

[0077] The reverse inlet valve 7 is connected between the inlet pipe and the reverse distributor 10-2;

[0078] The forward concentrate valve 9 is connected between the reverse water distributor 10-2 and the concentrate return pipe 13;

[0079] The reverse concentrate valve 8 is connected between the forward water distributor 10-1 and the concentrate return pipe 13.

[0080] By controlling the switching combination of the above valves, the two connection states can be switched:

[0081] First connected state (forward operation): Open the forward inlet valve 6 and the forward concentrate valve 9, and close the reverse inlet valve 7 and the reverse concentrate valve 8. At this time, wastewater enters the membrane module through the forward distributor 10-1 and flows out through the reverse distributor 10-2 to the concentrate return pipe.

[0082] Second connection state (reverse operation): Open the reverse inlet valve 7 and the reverse concentrate valve 8, and close the forward inlet valve 6 and the forward concentrate valve 9. At this time, wastewater enters the membrane module through the reverse distributor 10-2 and flows out from the forward distributor 10-1 to the concentrate return pipe.

[0083] It should be noted that, Figure 1 The valve assembly consisting of four valves shown is only one preferred embodiment of the present invention. For those skilled in the art, the concept of "valve assembly" should be interpreted broadly and is not limited to four independent valve units. For example, the valve assembly can be implemented as an integrated multi-way directional valve, a solenoid valve assembly, or a combined valve block driven by a pneumatic / electric actuator, as long as it can achieve the aforementioned function of selectively connecting the inlet pipe to the forward distributor 10-1 or the reverse distributor 10-2, and simultaneously connecting the concentrate return pipe 13 to another distributor. Any valve arrangement capable of switching between the first and second connection states falls within the protection scope of the "valve assembly" of this invention.

[0084] One end (inlet end) of multiple membrane modules 5 is connected to the forward distributor 10-1 through the inlet branch pipe 12-1, and the other end (concentrate end) is connected to the reverse distributor 10-2 through the concentrate branch pipe 12-2.

[0085] like Figures 6-8 As shown, the forward water distributor 10-1 and the reverse water distributor 10-2 of the present invention have the same structure and are configured to evenly distribute fluid to each branch pipe connected to them. Both include a valve drive mechanism 101, a valve housing 108, a valve plate 109, and short pipe joints 1012. The valve housing 108 has several through short pipe joints 1012 on opposite outer walls. A valve plate 109 is provided between the through short pipe joints 1012. Several valve plate holes 1010 are arranged on the valve plate 109. The valve plate holes 1010 are through holes and are arranged corresponding to the short pipe joints 1012. The valve drive mechanism 101 is located outside the valve housing 108, and the power output end of the valve drive mechanism 101 is connected to the valve plate 109. The valve plate 109 is driven by the valve drive mechanism 101 to slide back and forth in the valve housing 108, so that the through short pipe joints 1012 are either connected or disconnected.

[0086] The forward and reverse water distributors of this invention enable a single valve plate to control multiple external pipes. The valve plate has several through holes arranged in a row, each corresponding to a short pipe connector. A single drive mechanism can simultaneously control the opening and closing of multiple inlets and outlets within the valve, reducing energy consumption and operating costs compared to existing multi-drive valves. Since the external pipes are connected to the short pipe connectors on the valve body, the forward and reverse water distributors of this invention can flexibly increase or decrease the number of connected external pipes based on the number of connected short pipe connectors, thus facilitating practical production applications. Furthermore, the forward and reverse water distributors of this invention are detachable, allowing for easy on-site replacement of parts in case of malfunction, which is beneficial for maintenance and repair of the device.

[0087] Forward operation mode: Open the forward inlet valve 6 and the forward concentrate valve 9, and close the reverse inlet valve 7 and the reverse concentrate valve 8. The pressurized wastewater enters the forward distributor 10-1 via the second water pump 4 and the forward inlet valve 6, and is evenly distributed to each membrane module 5, flowing sequentially through the membrane elements connected in series. The permeate (permeate) is collected from the permeate side of the membrane element to the permeate pipe 11, and finally discharged or reused via the permeate discharge valve 21 and the permeate discharge pipe 22.

[0088] The concentrate is discharged from the concentrate end of membrane module 5, collected by reverse distributor 10-2, and enters concentrate return pipe 13 through forward concentrate valve 9. The concentrate can be partially returned to the inlet of the second water pump 4 for circulation through concentrate return control valve 15, and partially returned to the front-end anaerobic reactor through concentrate return anaerobic control valve 16.

[0089] After the set operating time for forward water intake is completed, the first water pump 3 and the second water pump 4 are shut down.

[0090] Reverse operation mode: Open the reverse inlet valve 7 and the reverse concentrate valve 8, and close the forward inlet valve 6 and the forward concentrate valve 9. At this time, the wastewater flow direction is opposite to the forward direction. The pressurized wastewater enters the reverse distributor 10-2 via the second pump 4 and the reverse inlet valve 7, enters from the original concentrate end of the membrane module 5, flows in the reverse direction through the series-connected membrane elements, and finally enters the concentrate return pipe 13 from the original inlet end via the forward distributor 10-1 and the reverse concentrate valve 8. The permeate end (permeate pipe 11) remains unchanged. Periodically switching the operating direction can effectively disturb and flush the pollutant layer on the membrane surface, delaying membrane fouling.

[0091] The switching between the first and second connectivity states can be automatically adjusted based on the system's operating time, such as 4 to 8 hours, or the system's maximum pressure, such as being 10% higher than the set pressure. The switching between the first and second connectivity states can be achieved by triggering any condition.

[0092] Regarding the cleaning system: The cleaning system shares most of its piping with the operating system. The cleaning fluid storage tank 17 stores clean water or chemical cleaning agent. During cleaning, the third water pump 18 is started, and the cleaning control valve 19 is opened, allowing the cleaning fluid to be injected into the inlet pipe downstream of the outlet of the second water pump 4. By controlling the valve group of the flow direction switching system, both forward and reverse flushing of the membrane module 5 with the cleaning fluid can be achieved, resulting in a more thorough cleaning. Permeate water can be returned to the cleaning fluid storage tank 17 via the permeate water return control valve 20 as supplementary flushing water.

[0093] Regarding the pressure protection device: To ensure the safe and stable operation of the device under high pressure (5-15 kg / cm²), a pressure protection device is installed. The pressure relief valve can be installed on the outlet pipe of the second water pump 4 or the inlet main pipe of the membrane module. It automatically opens to relieve pressure when the system pressure exceeds the set safety value. Pressure sensors can be installed at key locations such as the outlet of the second water pump 4, the inlet main pipe of the membrane module 5, or the product water pipe to monitor the pressure in real time and communicate with the PLC control system to realize overpressure alarms, pump frequency regulation, or automatic switching of cleaning programs.

[0094] Regarding membrane modules and operating parameters: The membrane housing is preferably made of 316L stainless steel, and the membrane elements are tubular membranes capable of withstanding high pressure. The number of membrane modules connected in parallel can be determined according to the design throughput (e.g., 50, 100, 200, 500 m³ / d) as 2, 4, 8, or more modules. The system operating pressure is set at 3-10 kg / cm² or higher; under these conditions, the membrane flux can be stabilized at 35-60 L / (m²·h).

[0095] The switching cycle between the first and second connection states can be set according to the influent water quality, for example, switching once every 12 or 24 hours of operation. The chemical cleaning cycle can be extended to 30-45 days.

[0096] Wastewater treatment method examples:

[0097] The above-mentioned device is used to treat landfill leachate or anaerobic fermentation biogas slurry from kitchen waste (COD≥20000 mg / L, SS≥30000 mg / L).

[0098] After pretreatment, the biogas slurry enters the anaerobic reactor, and the resulting anaerobic effluent enters this device.

[0099] Start the device and set it to forward operation mode. Control the operating pressure at 3~10 kg / cm² according to the water quality and system operation conditions, and run continuously for 4 hours.

[0100] The PLC control system automatically switched to reverse operation mode and continued to run for 4 hours.

[0101] This cycle repeats continuously, and during operation, the membrane flux remains stable at around 45 L / (m²·h), and the quality of the produced water meets the standards.

[0102] The flushing setting is set so that when the running time reaches 4 to 8 hours, the system enters the forward flushing state, and the flushing time is 1 to 5 minutes.

[0103] The PLC control system automatically switches to reverse operation mode and continues to run for 1 to 5 minutes.

[0104] The chemical cleaning setup is as follows: after 30 days of system operation, when the transmembrane pressure difference rises to the set value, the system automatically initiates the cleaning program: first, it rinses with clean water in both forward and reverse directions for 1-5 minutes each, then injects a specific chemical cleaning agent for both forward and reverse chemical cleaning for 30 minutes each. After cleaning, the membrane flux recovers to more than 95% of its initial value.

[0105] After cleaning is completed, the device automatically resumes normal operation.

[0106] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0107] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An external tubular anaerobic MBR membrane device for treating high-suspended-solids organic wastewater, characterized in that, include: The inlet pipeline is used to transport the anaerobic effluent to be treated; Multiple membrane modules (5) are connected in parallel on the water inlet pipe. Each membrane module (5) includes a membrane shell and at least two membrane elements disposed inside the membrane shell. The at least two membrane elements are connected end to end in series within the membrane shell to form an independent series flow channel. The forward water distributor (10-1) is connected to the inlet end of each membrane module (5); The reverse water distributor (10-2) is connected to the concentrate end of each membrane module (5); A permeate collection system, connected to the permeate end of each membrane module (5), is used to collect permeate; A concentrate return pipe (13) is connected to the concentrate end of each membrane module (5); A flow direction switching system, including a valve assembly configured to selectively switch to: In the first connection state, the inlet pipe is connected to the forward water distributor (10-1), and the concentrate return pipe (13) is connected to the reverse water distributor (10-2); and, In the second connection state, the water inlet pipe is connected to the reverse water distributor (10-2), and the concentrated water return pipe (13) is connected to the forward water distributor (10-1).

2. The external tubular anaerobic MBR membrane device according to claim 1, characterized in that, The valve assembly includes: A positive inlet valve (6) has its inlet connected to the inlet pipe and its outlet connected to the inlet end of the membrane module (5); A reverse feed valve (7) has its inlet connected to the feed line and its outlet connected to the concentrate end of the membrane module (5); A positive concentrate valve (9) has its inlet connected to the concentrate end of the membrane module (5) and its outlet connected to the concentrate return pipe (13). A reverse concentrate valve (8) has its inlet connected to the inlet of the membrane module (5) and its outlet connected to the concentrate return pipe (13). The first connected state is achieved by opening the forward inlet valve (6) and the forward concentrate valve (9) and closing the reverse inlet valve (7) and the reverse concentrate valve (8); the second connected state is achieved by opening the reverse inlet valve (7) and the reverse concentrate valve (8) and closing the forward inlet valve (6) and the forward concentrate valve (9).

3. The external tubular anaerobic MBR membrane device according to claim 1, characterized in that, The water inlet pipeline includes a main water inlet pipe and water inlet branch pipes (12-1) connected to each membrane module (5). The concentrate return pipe (13) is connected to the concentrate end of each membrane module (5) through multiple concentrate branch pipes (12-2).

4. The external tubular anaerobic MBR membrane device according to claim 1, characterized in that, The membrane housing is made of corrosion-resistant metal or plastic; the device is configured to operate stably at an operating pressure of 3~10 kg / cm².

5. The external tubular anaerobic MBR membrane device according to claim 1, characterized in that, A second water pump (4) is installed on the water inlet pipe; it also includes a pressure protection device, which includes a pressure relief valve and a pressure sensor, wherein... The pressure relief valve is installed on the outlet pipe of the second water pump (4) or the inlet main pipe of the membrane module (5); The pressure sensor is installed on the outlet pipe of the second water pump (4), the inlet end of the membrane module (5), or the product water collection system, and is connected in communication with the control system.

6. The external tubular anaerobic MBR membrane device according to claim 1, characterized in that, It also includes a chemical cleaning / rinsing assembly, comprising: a cleaning fluid storage tank (17), a third water pump (18), and a cleaning control valve (19), wherein the inlet of the third water pump (18) is connected to the cleaning fluid storage tank (17), and the outlet of the third water pump (18) is connected to the downstream outlet of the second water pump (4) in the water inlet pipeline through the cleaning control valve (19).

7. The external tubular anaerobic MBR membrane device according to claim 1, characterized in that, The forward water distributor (10-1) and the reverse water distributor (10-2) have the same structure and are configured to evenly distribute fluid to the branch pipes connected to them. Both include a valve drive mechanism (101), a valve housing (108), and a valve plate (109). The valve housing (108) has several through short pipe joints (1012) on its opposite outer walls. A valve plate (109) is provided between the through short pipe joints (1012). Several valve plate holes (1010) are arranged on the valve plate (109). The valve plate holes (1010) are through holes, and the valve plate holes (1010) are arranged corresponding to the short pipe joints (1012). The valve drive mechanism (101) is located outside the valve housing (108), and the power output end of the valve drive mechanism (101) is connected to the valve plate (109). The valve plate (109) is driven to slide back and forth in the valve housing (108) by the valve drive mechanism (101), so that the through short pipe joint (1012) is either connected or disconnected.

8. A membrane module, characterized in that, The external tubular anaerobic MBR membrane device according to any one of claims 1-7 includes a membrane shell and at least two membrane elements disposed inside the membrane shell, wherein the at least two membrane elements are connected end to end in series by a high-strength sealing joint (24). The high-strength sealing joint (24) is located at both ends of the membrane module (5) and is fixedly connected to the membrane shell by flange bolts or a mortise bolt. A sealing gasket (25) is provided between the high-strength sealing joint (24) and the membrane module (5) to ensure the sealing between the two. The high-strength sealing joint (24) is provided with multiple elbow connecting pipes (26) and one or more membrane module inlet ends (27) and outlet ends (28) according to the number of membrane elements in the membrane module.

9. A wastewater treatment method using an external tubular anaerobic MBR membrane device as described in any one of claims 1-7, characterized in that, The device further includes a product water discharge valve (21) and a product water discharge pipe (22) installed on the product water pipe (11), and a concentrate return control valve (15) and a concentrate return anaerobic control valve (16) installed on the concentrate return pipe (13). The method includes: Forward operation mode: The flow direction switching system is switched to the first connection state. The pressurized wastewater enters each membrane module (5) through the inlet pipe and the forward distributor (10-1), and flows through the membrane elements in series in sequence. The permeate is discharged through the permeate collection system. The concentrate flows out from the concentrate end of the membrane module (5) through the reverse distributor (10-2) and the concentrate return pipe (13), part of which flows back to the inlet pipe inlet and part of which flows back to the front anaerobic reactor. When the flow direction switching system is switched to the second connection state, the pressurized wastewater enters from the concentrate end of the membrane module (5) through the inlet pipe and the reverse distributor (10-2), flows in the reverse direction through the series membrane elements, and flows out from the inlet end of the membrane module (5) through the forward distributor (10-1) and the concentrate return pipe (13).

10. The wastewater treatment method of the external tubular anaerobic MBR membrane device according to claim 9, characterized in that, It also includes forward and / or reverse chemical cleaning / rinsing modes: Close the permeate discharge valve (21), concentrate return control valve (15) and concentrate return anaerobic control valve (16), start the third water pump (18), and open the cleaning control valve (19) and permeate return control valve (20). Forward chemical cleaning: The flow direction switching system is switched to the first connected state, and the chemical cleaning solution flows forward through the membrane elements in each membrane module (5), while the permeate and concentrate are returned to the cleaning solution storage tank (17). Reverse chemical cleaning: The flow direction switching system is switched to the second connected state, and the chemical cleaning solution flows in reverse through the membrane elements in each membrane module (5), while the permeate and concentrate are returned to the cleaning solution storage tank (17).

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