A DT-MBR with an improved outlet pipeline of the filter cloth assembly

Abstract

The present invention discloses a DT-MBR with an improved water outlet pipeline of a filter cloth assembly. The DT-MBR is a filtration medium series membrane bioreactor. The filter cloth assembly of the membrane bioreactor is connected to the water outlet pipeline through its water inlet end connection pipe. The water outlet pipeline includes a vertical pipe A and a vertical pipe B. The tops of both vertical pipes are open, and the middle parts are connected and conducted through a pipeline. The bottom end of the vertical pipe A is connected and conducted to the connection pipe through a pipeline, and the bottom end of the vertical pipe B is led into the bottom end inside the filter tank through a pipeline. The water outlet pipeline of the filter cloth assembly of the present invention can discharge the gas in the water into the atmosphere, completely solve the problem of air bubbles in the influent water of the upflow ultra-light filter material filter tank, effectively improve the filtration performance of the filter tank, improve the quality of the filtered water. In addition, it also solves the problem of air resistance in the water outlet pipeline of the filter cloth assembly and the problem of water backflow in the filter tank after the self-priming pump stops.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and particularly relates to a DT-MBR with an improved outlet pipeline of a filter cloth assembly. Background Art

[0002] The membrane bioreactor (MBR) has the advantages of strong biodegradation ability, good effluent quality, short process flow, small floor area, and less excess sludge. It was once considered the most promising sewage treatment technology in the 21st century. However, membrane fouling seriously restricts the popularization and application of this technology. So-called membrane fouling mainly refers to the phenomenon that colloids, suspended solids, and soluble substances in the feed liquid adsorb and deposit on the membrane surface and within the membrane pores, resulting in an increase in filtration resistance and a decrease in membrane flux. There are many membrane fouling control technologies, including membrane material modification, quorum sensing and quorum quenching, electrolysis, addition of modified flocculants, ultraviolet / Fe(II) synergistic activation pretreatment, sodium percarbonate oxidation-coagulation coupling, ultraviolet advanced oxidation pretreatment, ultrasonic cleaning, intermittent operation of membrane modules, increasing membrane surface shear force, reducing membrane flux, backwashing, etc. However, the problem of membrane fouling is still serious so far. When irreversible fouling becomes severe to a certain extent, chemical cleaning must be carried out, which will accelerate the aging of the membrane material, and the membrane module must be replaced regularly. The high price of the membrane module makes the operation cost of MBR very high.

[0003] Therefore, the inventor connected a cheap filter cloth assembly in series with an upflow ultra-light filter media filter to replace the microfiltration or ultrafiltration membrane module, and developed a filtration medium series-connected membrane bioreactor (DT-MBR) (see CN 115465945 A for details). Among them, the filter cloth assembly mainly performs solid-liquid separation, and the upflow ultra-light filter media filter deeply treats the effluent of the filter cloth assembly. The inventor used DT-MBR to treat domestic sewage (the raw water quality is shown in Table 1) and studied its operation conditions.

[0004] Table 1 Raw Water Quality

[0005]

[0006]

[0007] Note: The values with * in parentheses are average values, n>20.

[0008] The water treatment capacity of the DT-MBR test device is 100 L / h, the volume of the aeration tank is 0.8 m3, the hydraulic retention time is 8 h, and the sludge age is 30 d; the filter cloth component is of plate-frame structure, with double-sided water inlet and bottom water outlet, and the total filtration area is 1.0 m2; the filter cloth is made of polyester, with an air permeability of 18-25 L / m2·s and a flux of 100 L / m2·h; the up-flow ultra-light filter media filter is an organic glass cylinder with a diameter of DN 200 mm, and the filter media used is polystyrene spherical particles with a bulk density of 20 kg / m3, the filter media particle size is 1.0-2.0 mm, the particle size non-uniformity coefficient K80 is 1.17, the filter layer thickness is 700 mm, and the filtration rate is 3.2 m / h.

[0009] In the initial stage of system operation, the self-priming pump was not started, and activated sludge was cultivated by the method of "water inlet - blank aeration - static sedimentation - discharging supernatant". Since the 5th d (MLSS was 6850 mg / L), the self-priming pump was started to pump out water, and the complete DT-MBR process was officially put into operation. It was found in the test that the initial effluent turbidity and suspended solid concentration (SS) of the filter cloth component were both very high, reaching 138.5 NTU and 883 mg / L respectively; after 1 h of filtration, the two indicators rapidly dropped to 47.1 NTU and 337 mg / L; with the extension of filtration time, the two indicators continued to decline and decreased to 6.5 NTU and 80 mg / L at the 21st h; continuing filtration, the decline rate of the two indicators slowed down; when filtered to the 72nd h, the two indicators were 3.8 NTU and 40 mg / L respectively (the variation of the effluent turbidity and SS of the filter cloth component with filtration time will Figure 1 、 Figure 2 ). In addition, unexpectedly, the effluent turbidity and SS of the filter cloth component could still remain stable after backwashing, and the two indicators were 4.2-6.4 NTU and 41-78 mg / L respectively. At this time, the average turbidity and SS of the effluent from the up-flow ultra-light filter media filter (i.e., the final effluent of DT-MBR) were 0.87 NTU and 6.3 mg / L respectively. It can be seen that the series-connected filter cloth component and up-flow ultra-light filter media filter can perfectly replace the microfiltration membrane component and achieve good solid-liquid separation effect. Since the filter cloth component has a low price (only 1 / 5 of the polyvinylidene fluoride hollow fiber microfiltration membrane of the same area), a large flux (20-50 times that of the polyvinylidene fluoride hollow fiber microfiltration membrane), and the price of the polystyrene ultra-light filter media is also very low (only 1 / 2 of the quartz sand filter media of the same volume), and the filtration rate of the up-flow ultra-light filter media filter is very high (the normal filtration rate can reach 8-12 m / h), DT-MBR can greatly reduce the costs generated by the use and replacement of membrane components in traditional MBR (the reduction exceeds 90%).

[0010] The existing dynamic membrane theory cannot explain the phenomenon that the filter cloth component can still maintain good and stable solid-liquid separation effect after backwashing. The so-called dynamic membrane refers to using inexpensive coarse-pore materials (such as non-woven fabrics, filter cloths, nylon meshes, etc.) instead of expensive membrane components, and realizing solid-liquid separation by using the cake layer (i.e., dynamic membrane) formed on the surface of the coarse-pore materials. The coarse-pore materials mainly play a role in supporting the dynamic membrane, generally having larger pore diameters and very small pore resistance. The formation process of the dynamic membrane can be divided into three stages, namely the formation stage, the stable stage, and the cleaning and regeneration stage. Among them, the formation stage is the process in which the coarse-pore materials continuously intercept activated sludge and the cake layer gradually adheres and matures. The stable stage mainly refers to the period between the formation of the dynamic membrane and the cleaning and regeneration, which is the real effective working process. It not only depends on the performance of the dynamic membrane (such as the thickness and porosity of the dynamic membrane), but also is affected by operating conditions such as operating pressure, cross-flow velocity, temperature, and aeration intensity. After the dynamic membrane operates stably for a period of time, the filtration resistance will increase rapidly and the flux will decrease significantly. It is necessary to clean and regenerate to restore the filtration performance. The morphology and structure of the dynamic membrane after cleaning will be damaged, and the effluent quality will deteriorate for a period of time. Thus, it can be seen that the morphology and structure of the dynamic membrane are constantly changing during the operation process, resulting in very unstable effluent quality.

[0011] In the previous experiments, the solid-liquid separation effect of the filter cloth component gradually improved and finally tended to be stable in the initial stage of filtration, which is in line with the characteristics of the formation and stable process of the dynamic membrane; but it can still maintain good and stable after backwashing, which is obviously inconsistent with the unstable characteristics of the dynamic membrane. The total filtration resistance of the filter cloth is mainly composed of the cake layer resistance and the filter cloth pore resistance. Therefore, the filtration performance of the filter cloth should also be related to the cake layer and the filter cloth pores. Since the morphology and structure of the cake layer are constantly changing during the operation process, resulting in very unstable effluent quality of the dynamic membrane, it is reasonable to believe that the reason why the effluent quality of the filter cloth component can still maintain good and stable after backwashing can only be related to the filter cloth pores. For this reason, the inventor proposed the concept of in-situ self-generated static membrane (or self-generated static membrane), believing that after a long time of filtration, a layer of inner-lining sludge with strong adhesion force (i.e., in-situ self-generated static membrane) must be formed and adhered on the inner wall of the filter cloth pores, making the pore diameter smaller and the sieving effect stronger; when the pore diameter is small enough, the sieving effect of the filter cloth pores will play a dominant role in solid-liquid separation. According to the strength of the adhesion force, the in-situ self-generated static membrane can be divided into a double-layer structure, with the inner layer being the tightly adhered layer and the outer layer being the loosely adhered layer. During backwashing, the gas / water flow shear force and the adhesion force of the in-situ self-generated static membrane can reach a certain balance, causing the loosely adhered layer to peel off, while the morphology and structure of the tightly adhered layer still remain relatively stable. Therefore, although the pore diameter of the filter cloth will increase slightly after backwashing, the pore sieving effect still dominates, which should be the fundamental reason why the solid-liquid separation effect of the filter cloth component can still maintain good and stable after backwashing.

[0012] After detection and calculation, it is known that the filtration resistance (Rm ) is 0.84E+11 m -1 , the pore resistance of the filter cloth (R p ) after operation (before flushing) is 1.67E+11 m -1 , and the R p after flushing is 1.39E+11 m -1 , which proves the existence of the in-situ self-generated static membrane from the side. In addition, it is found in the experiment that the air flushing intensity has an important influence on the filtration performance of the filter cloth module. On the premise that other conditions remain unchanged, after flushing with an air flushing intensity of 1.5 L·s -1 ·m -2 , the transmembrane pressure difference (TMP) of the filter cloth module at the 24th hour of filtration is 0.06 MPa; when the air flushing intensity is increased to 5.0 L·s -1 ·m -2 , the TMP of the filter cloth module at the 24th hour of filtration is only 0.04 MPa, which proves the existence of the in-situ self-generated static membrane from another side.

[0013] Although DT-MBR has good solid-liquid separation effect, during the later operation process, it is found that there is a large amount of gas in the water discharged from the filter cloth module. There are two reasons for the analysis: one is that there is an aeration head under the filter cloth module. The shear force generated by the bubbles released by the aeration head on the surface of the filter cloth during the rising process can control the thickness of the mud cake layer to reduce the filtration resistance, but some of the bubbles will penetrate through the filter cloth under the suction of the self-priming pump and enter the inside of the filter cloth module; the other is that as the filtration time prolongs, the filtration resistance of the filter cloth gradually increases. Under the suction of the self-priming pump, the water pressure inside the filter cloth module and in the outlet pipe will decrease (the vacuum degree can reach 0.065 MPa), and the saturated solubility of air in water will decrease. Therefore, some gases will precipitate from the water. A large number of bubbles will be generated after the water containing a large amount of gas enters the bottom of the filter tank. The bubbles penetrate the filter layer from bottom to top, which will disturb the filter layer structure, resulting in some water to be filtered penetrating the filter layer and reducing the effluent quality. In addition, some gases will accumulate in the outlet pipe of the filter cloth module to form an air bag, which will reduce the cross-sectional area of the water flow, increase the local head loss, and in severe cases, even form an air blockage, resulting in no water flowing out of the pipeline and a sharp rise in the pressure inside the pipeline, and a significant increase in the pipeline leakage rate and the probability of pipe bursting.

[0014] In addition, it is found during operation that since the filter cloth assembly and the outlet pipe are in a negative pressure state, once the self-priming pump stops running, the water in the upflow ultra-light filter media filter tank will flow back into the filter cloth assembly, the water level in the filter tank will drop significantly, the buoyancy force on the ultra-light filter media will decrease accordingly, and the filter layer structure will become loose. When the self-priming pump resumes operation, the quality of the initial filtered water in the filter tank is poor. If the self-priming pump operates intermittently (for example, the applicant is currently conducting experimental research on treating slightly polluted lake water using DT-MBR, and the self-priming pump operates in an intermittent mode of "on for 8 minutes and off for 2 minutes"), the impact of the water backflow problem in the filter tank on the quality of the final effluent will be very serious. Summary of the Invention

[0015] To overcome the drawbacks and deficiencies of the prior art, the purpose of the present invention is to provide a DT-MBR with an improved outlet pipeline for the filter cloth assembly.

[0016] The present invention is implemented as follows. A DT-MBR with an improved outlet pipeline for the filter cloth assembly, the DT-MBR being a filtration medium series membrane bioreactor, the membrane bioreactor including an aeration tank and an upflow ultra-light filter media filter tank. Among them, the top of the aeration tank is filled with water through a raw water pipe, and air is introduced into the bottom through a gas supply pipe. The outlet end of the gas supply pipe is connected to an aeration head, and a filter cloth assembly is provided in the aeration tank; the filtered water outlet of the filter cloth assembly is connected to the inlet end of a connecting pipe, and a second water flushing pipe and a second gas flushing pipe are connected to the connecting pipe;

[0017] The top of the filter tank is connected to a clear water pipe, a first water flushing pipe is connected to the clear water pipe, a filter plate is provided on the cross-section inside the filter tank, a filter layer composed of ultra-light filter media is provided below the filter plate, the bottom of the filter tank is connected to a flushing wastewater discharge pipe, and a first gas flushing pipe is introduced into the bottom of the filter tank;

[0018] Valves are provided on the raw water pipe, the gas supply pipe, the second water flushing pipe, the second gas flushing pipe, the clear water pipe, the first water flushing pipe, the flushing wastewater discharge pipe, and the first gas flushing pipe;

[0019] The DT-MBR further includes an outlet pipeline, the outlet pipeline including an A vertical pipe and a B vertical pipe. The tops of both vertical pipes are open, and the middle parts are connected and conducted through a horizontal cross pipe. The bottom end of the A vertical pipe is connected and conducted to the connecting pipe through a pipeline, and the bottom end of the B vertical pipe is introduced into the bottom end inside the filter tank through a pipeline.

[0020] Preferably, a self-priming pump is installed on the A vertical pipe or the pipeline connecting its bottom end.

[0021] Preferably, a valve is installed on the B vertical pipe or the pipeline connecting its bottom end.

[0022] Preferably, the horizontal elevation of the horizontal cross pipe is higher than the highest designed water level of the filter tank.

[0023] The present invention overcomes the shortcomings of the prior art and provides a DT-MBR with an improved water outlet pipeline of a filter cloth assembly. The water outlet pipeline connected to the connecting pipe of the filter cloth assembly is designed as an "H"-shaped water outlet pipeline structure. The tops of the two pipes at the upper ends of the "H"-shaped water outlet pipeline are opened and connected to the atmosphere, so that a large amount of gas in the water can be discharged, which completely solves the problem of excessive bubbles in the water at the bottom of the upward flow ultra-light filter material filter tank.

[0024] Compared with the shortcomings and deficiencies of the prior art, the present invention has the following beneficial effects:

[0025] (1) The water outlet pipeline of the filter cloth assembly of the present invention can discharge the gas in the water into the atmosphere, which completely solves the problem of bubbles in the water inlet of the upward flow ultra-light filter media filter, and can effectively improve the filtering performance of the filter and improve the water quality of the filtered water;

[0026] (2) The water outlet pipeline of the filter cloth assembly of the present invention can discharge the gas in the water into the atmosphere, preventing the gas from accumulating inside the pipeline (at the highest point) to form air pockets (the formation of air pockets will reduce the water flow cross-sectional area, increase local head loss, and even form air blockage in severe cases);

[0027] (3) In the water outlet pipe of the filter cloth assembly of the present invention, the upper ends of the two vertical pipes A and B are open, so that the filtering driving force of the upward flow ultra-light filter media filter tank is changed from pressure flow to gravity flow, and the elevation of the horizontal cross pipe between the two vertical pipes A and B is higher than the highest design water level of the filter tank, which not only ensures the stability of the water head during filtration, but also avoids the phenomenon of water backflow in the filter tank when the self-priming pump is stopped (the pressure in the filter cloth assembly and the water outlet pipe when the self-priming pump is in operation is negative pressure. After the self-priming pump is stopped, the water in the filter tank will flow back into the filter cloth assembly, the water level in the filter tank will drop, the buoyancy of the ultra-light filter media will decrease, the filter layer structure will become loose, the filtering performance will decrease, and the initial filtered water quality will deteriorate when the filtration is resumed). BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the relationship between the effluent turbidity of the filter cloth assembly and the filtration time in the existing DT-MBR;

[0029] Figure 2 It is the relationship between the SS concentration of the effluent from the filter cloth assembly and the filtration time in the existing DT-MBR;

[0030] Figure 3 It is a process structure diagram of the DT-MBR of the present invention having a water outlet pipe of a filter cloth assembly. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] An embodiment of the present invention discloses a DT-MBR with an improved water outlet pipeline of a filter cloth assembly. The DT-MBR is a filtration medium series membrane bioreactor, and the membrane bioreactor includes an aeration tank 2 and an upflow ultra-light filter media filter tank 9. Among them, the top of the aeration tank is filled with water through a raw water pipe 1, and air is introduced through an air supply pipe 3 at the bottom. The air outlet end of the air supply pipe is connected to an air diffuser 4, and a filter cloth assembly 5 is arranged in the aeration tank; the filtered water outlet of the filter cloth assembly is connected to the inlet end of a connecting pipe 6, and a second water flushing pipe 16 and a second air flushing pipe 17 are connected to the connecting pipe; the top of the filter tank is connected to a clear water pipe 12, and a first water flushing pipe 13 is connected to the clear water pipe. A filter plate 11 is arranged on the cross-section in the filter tank, and a filter layer 10 composed of ultra-light filter media is arranged below the filter plate. The bottom of the filter tank is connected to a flushing wastewater discharge pipe 15, and a first air flushing pipe 14 is introduced into the bottom of the filter tank; valves are arranged on the raw water pipe, the air supply pipe, the second water flushing pipe, the second air flushing pipe, the clear water pipe, the first water flushing pipe, the flushing wastewater discharge pipe, and the first air flushing pipe; the DT-MBR further includes a water outlet pipeline 8, and the water outlet pipeline includes an A vertical pipe and a B vertical pipe. The tops of both vertical pipes are open, and the middle parts are connected and conducted through a horizontal cross pipe. The bottom end of the A vertical pipe is connected and conducted to the connecting pipe through a pipeline, and the bottom end of the B vertical pipe is introduced into the bottom end inside the filter tank.

[0033] It is easy to understand that in order to provide the water outlet power of the filter cloth assembly, a self-priming pump 7 is installed on the A vertical pipe or the pipeline connected to its bottom end. It is easy to understand that correspondingly, a valve is installed on the B vertical pipe or the pipeline connected to its bottom end.

[0034] In the embodiment of the present invention, preferably, the horizontal elevation of the horizontal cross pipe is higher than the highest designed water level of the filter tank. Among them, the upper ends of the A and B vertical pipes are open, so that the filtration driving force of the upflow ultra-light filter media filter tank changes from pressure flow to gravity flow, and the elevation of the horizontal cross pipe between the A and B vertical pipes is higher than the highest designed water level of the filter tank, which not only ensures the stability of the acting water head during filtration, but also avoids the phenomenon of the water in the filter tank flowing back when the self-priming pump stops (the pressure in the filter cloth assembly and the water outlet pipeline is negative under the operating state of the self-priming pump. After the self-priming pump stops, the water in the filter tank will flow back into the filter cloth assembly, the water level in the filter tank will drop, the buoyancy received by the ultra-light filter media will decrease, the filter layer structure will become loose, the filtration performance will decline, and the initial filtered water quality will deteriorate when the filtration is restored).

[0035] The above water outlet pipeline of the present invention as a whole presents an "H" shape. For the convenience of description, in the embodiment of the present invention, this water outlet pipeline is described as an "H" type water outlet pipeline.

[0036] When the DT-MBR of the present invention operates, the raw water to be treated flows into the aeration tank from the raw water pipe, and the air provided by the air pump enters the aeration tank from the air supply pipe and the aeration head to provide the dissolved oxygen required by the activated sludge, and at the same time makes the activated sludge and the substrate fully mixed; the activated sludge is intercepted by the filter cloth, and the relatively clean water enters the bottom of the up-flow ultra-light filter media filter through the filter cloth and the "H"-shaped outlet pipeline under the suction of the self-priming pump, passes through the filter layer and the filter plate from bottom to top, and finally flows out through the outlet pipe of the filter. The working cycle of the filter cloth assembly is 24 h, and the working cycle of the up-flow ultra-light filter media filter is 6 d.

[0037] The flushing method of the filter cloth assembly is "air flushing - water flushing", and the specific steps are as follows:

[0038] (1) Air enters the inside of the filter cloth assembly from the second air flushing pipe, and flushes the filter cloth from the inside to the outside. The air flushing intensity is 1.5 - 4.5 L / (s·m2), and the time is 7 - 9 min;

[0039] (2) Stop air flushing, and clear water enters the inside of the filter cloth assembly from the second water flushing pipe, and flushes the filter cloth from the inside to the outside. The water flushing intensity is 1 - 2 L / (s·m2), and the time is 1 - 2 min.

[0040] The flushing method of the up-flow ultra-light filter media filter is "air flushing - draining - water flushing" (see CN 115465945A for details), and the specific steps are as follows:

[0041] (1) Air enters the bottom of the filter from the first air flushing pipe, and flushes the filter media from bottom to top. The air flushing intensity is 8 L / (s·m2), and the time is 3 min;

[0042] (2) Stop air flushing, and drain the flushing wastewater in the filter within 3 - 5 min;

[0043] (3) Clear water enters the upper part of the filter from the first water flushing pipe, and rinses the filter media from top to bottom. The water flushing intensity is 4 L / (s·m2), and the water flushing time is 3 - 5 min.

[0044] The test results over a period of half a year show that the DT-MBR of the present invention operates stably, and the effects of solid-liquid separation and the removal of organic matter and ammonia nitrogen are very good. The effects of denitrification and phosphorus removal are basically equivalent to those of the traditional aerobic MBR (the pollutant removal effects are shown in Table 2).

[0045] Table 2 Pollutant removal effects of DT-MBR

[0046]

[0047] Note: The values with * in parentheses are the averages, n = 12.

[0048] Traditional aerobic MBR can effectively remove organic matter and ammonia nitrogen, and can also remove suspended solids well, but its removal effect on total nitrogen (TN) and total phosphorus (TP) is poor (lacking anoxic and anaerobic environments). In addition, the main reason why traditional MBR is difficult to promote is that the membrane module is too expensive and has a short service life. The filter medium series-connected membrane bioreactor in the inventor's previous patent CN 115465945 A can well replace traditional MBR, but the following problems were found in the later operation: (1) the air resistance problem in the outlet pipe of the filter cloth module; (2) the disturbance problem of the filter layer structure caused by the rising of air bubbles in the filter tank inlet water; (3) the problem of water backflow in the filter tank when the self-priming pump stops. The existence of these three problems makes the treatment effect of DT-MBR very unstable, affecting both the effluent water quality and the operation energy consumption, and there is also a risk of pipe bursting. In the present invention, the outlet pipe of the filter cloth module is designed as an "H" type structure, the upper ends of the two vertical pipes A and B are open, and the elevation of the horizontal pipe between the two vertical pipes A and B is higher than the designed maximum water level of the filter tank, completely solving the above three problems. After running for up to half a year, as can be seen from Table 2 above, the DT-MBR of the present invention has a very stable treatment effect and a very stable effluent water quality.

[0049] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A DT-MBR with an improved outlet pipeline of a filter cloth component, the DT-MBR being a filtration medium series-connected membrane bioreactor, the membrane bioreactor including an aeration tank and an upflow ultra-light filter media filter tank, wherein, The top of the aeration tank is filled with water through the raw water pipe, and air is introduced through the air supply pipe at the bottom. The outlet end of the air supply pipe is connected to the aeration head, and a filter cloth assembly is provided in the aeration tank; the filtered water outlet of the filter cloth assembly is connected to the inlet end of the connecting pipe, and the second water flushing pipe and the second air flushing pipe are connected to the connecting pipe. The top of the filter tank is connected to the clear water pipe, and the first water flushing pipe is connected to the clear water pipe. A filter plate is provided on the cross-section inside the filter tank, and a filter layer composed of ultra-light filter media is arranged below the filter plate. The bottom of the filter tank is connected to the flushing wastewater discharge pipe, and the first air flushing pipe is introduced into the bottom of the filter tank. Valves are provided on the raw water pipe, the air supply pipe, the second water flushing pipe, the second air flushing pipe, the clear water pipe, the first water flushing pipe, the flushing wastewater discharge pipe, and the first air flushing pipe. It is characterized in that the DT-MBR further includes a water outlet pipeline, and the water outlet pipeline includes a vertical pipe A and a vertical pipe B. The tops of the two vertical pipes are both open, and the middle parts are connected and conducted through a horizontal cross pipe. The bottom end of the vertical pipe A is connected and conducted to the connecting pipe through a pipeline, and the bottom end of the vertical pipe B is introduced into the bottom end inside the filter tank through a pipeline. A self-priming pump is installed on the vertical pipe A or the pipeline connected to its bottom end. A valve is installed on the vertical pipe B or the pipeline connected to its bottom end. The horizontal elevation of the horizontal cross pipe is higher than the highest designed water level of the filter tank.

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