An OMA / A denitrification and phosphorus removal device and method based on MBR-MD coupling membrane

Abstract

The present invention provides an O-M-A / A denitrification and phosphorus removal device based on an MBR-MD coupled membrane. The present invention places an aerobic tank in front, and aerobic microorganisms convert ammonia nitrogen in sewage into nitrate nitrogen and nitrite nitrogen, which then flows into an anaerobic / anoxic zone, and convert nitrate nitrogen and nitrite nitrogen into nitrogen gas through a denitrification reaction. Therefore, the present invention does not need to denitrify by reflux, thus eliminating the need for reflux equipment and reducing system energy consumption; the present invention uses the principle of denitrification and phosphorus accumulation to place a deoxygenation membrane with a small diameter inside a filter membrane with a large diameter. Compared with the only interception and filtration function of a traditional MBR membrane module, the coupled membrane module has the functions of intercepting sludge, filtering produced water, deoxygenating nitrified liquid, and recycling and utilizing membrane purge aeration. At the same time, due to the multi-membrane nested design of the coupled membrane module, the anti-pollution ability and tensile strength of the coupled membrane filaments are enhanced, so that it requires less purge gas than traditional MBR membranes and is not prone to filament breakage.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to an OMA / A denitrification and dephosphorization device and method based on an MBR-MD coupling membrane. Background Art

[0002] In recent decades, with the widespread use of fertilizers, pesticides and detergents, nitrogen and phosphorus pollution and water eutrophication have become increasingly serious, and my country has also put forward higher and stricter standards and requirements for nitrogen and phosphorus emissions. With the continuous improvement of the country's requirements for sewage discharge, especially the increasingly stringent standards for nitrogen and phosphorus emissions, in order to achieve lower effluent requirements, the combination of traditional biochemical processes and MBR processes has become a research hotspot in sewage treatment processes in recent years.

[0003] The MBR process uses the membrane interception characteristics to replace the secondary sedimentation tank to achieve mud and water filtration, so that the biochemical system can reach a higher sludge concentration, the volume of the biochemical reaction zone can be greatly reduced, and the biochemical treatment capacity is enhanced. Among many biochemical processes, the AAO process is favored for its simple process flow and ability to achieve simultaneous nitrogen and phosphorus removal. Therefore, the AAO-MBR of the AAO process and the MBR process has received more and more attention and research, but the AAO-MBR process has the defect of high energy consumption. Its energy consumption per ton of water treatment is 2-3 times that of the traditional activated sludge method, which limits the promotion and application of this process.

[0004] The energy consumption of the AAO-MBR process mainly comes from the reflux of the AAO process and the membrane purge of the MBR process: In the traditional AAO process, denitrification and phosphorus removal are carried out by different bacteria in different reaction environments: denitrification uses nitrifying bacteria to convert ammonia nitrogen into nitrate nitrogen in an aerobic environment, and then denitrifying bacteria in an anoxic environment convert nitrate nitrogen into nitrogen gas, and phosphorus removal is achieved by using polyphosphate bacteria to release phosphorus in an anaerobic environment and then absorb phosphorus in an aerobic environment. Since the carbon source in the influent is limited, and both denitrifying bacteria and polyphosphate bacteria are heterotrophic bacteria, in order to ensure the intake of carbon sources required by denitrifying bacteria and polyphosphate bacteria, in the traditional AAO process, anaerobic tanks and anoxic tanks are usually placed in front to obtain carbon sources first, and then the reflux is used to return the nitrification liquid from the aerobic tank to the anoxic tank, and the polyphosphate bacteria from the aerobic tank to the anaerobic tank. Therefore, in order to achieve better denitrification and phosphorus removal effects, more carbon sources and larger reflux volumes are required. However, the domestic sewage in my country has the characteristics of low carbon-nitrogen ratio and low carbon-phosphorus ratio, which makes it difficult to meet the carbon source requirements of denitrifying bacteria and polyphosphate bacteria at the same time, resulting in competition between denitrifying bacteria and polyphosphate bacteria. In order to ensure the denitrification and phosphorus removal effect of the system, artificial carbon source supplementation is often required in many municipal projects. In the MBR process, due to the use of membrane suction filtration, under the interception effect of the membrane, the sludge concentration in the biological reaction zone can reach 2-3 times that of the traditional activated sludge method. In order to slow down the membrane pollution and blockage, the most mainstream method at present is to flush the membrane wires through a large amount of aeration at the bottom of the membrane module through a perforated pipe, so that the membrane wires shake. The air-water ratio is about 15:1 to 20:1. The aeration volume required for membrane purge aeration alone is much higher than that of the activated sludge method, which increases the aeration energy consumption. However, the oxygen transfer efficiency of large bubble aeration is low, and the aeration range is mainly concentrated near the membrane module. Therefore, the large amount of aeration used for membrane purge only plays a flushing and shaking role, and a large amount of oxygen can only be wasted. The aerobic pool also needs to be equipped with a microporous aeration device to supply oxygen to aerobic microorganisms.

[0005] Therefore, how to solve the problem of high energy consumption is a direction worth exploring. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide an OMA / A denitrification and phosphorus removal method based on MBR-MD coupling membrane. The method of the present invention has low energy consumption and good denitrification and phosphorus removal effects.

[0007] The present invention provides an OMA / A denitrification and dephosphorization device based on an MBR-MD coupling membrane, comprising:

[0008] Water inlet device;

[0009] An ultra-fine grid having an inlet connected to an outlet of the water inlet device;

[0010] The ultra-fine grid outlets are connected to the aerobic tank and the switchable anaerobic / anoxic tank respectively;

[0011] A microporous aeration plate disposed at the bottom of the aerobic tank;

[0012] an MBR-MD coupling membrane whose inlet is connected to the outlet of the aerobic tank;

[0013] The MBR-MD coupled membrane is connected to the switchable anaerobic / anoxic tank via a water production vacuum pump;

[0014] The switchable anaerobic / anoxic tank is provided with a suspended filler;

[0015] The MBR-MD coupling membrane comprises:

[0016] A coupled membrane module, an air collecting pipe arranged at the lower part of the coupled membrane module, and a water collecting pipe arranged at the upper part of the coupled membrane module; the coupled membrane module comprises an MBR membrane and a deoxygenation membrane arranged inside the MBR membrane; a membrane purge aeration device arranged at the lower part of the air collecting pipe, a blower for blowing air to the coupled membrane module, a water production vacuum pump connected to the water collecting pipe, and the air collecting pipe is connected to the microporous aeration disk at the bottom of the aerobic tank through the degassing vacuum pump.

[0017] Preferably, the deoxygenation membrane is an organic membrane or an inorganic membrane; the deoxygenation membrane is a hollow fiber membrane or a flat membrane; the pore size of the deoxygenation membrane is preferably 0.01-0.03 μm; the pore size of the MBR membrane is preferably 0.03-0.4 μm; the membrane purge aeration device is a perforated tube.

[0018] The deoxidation method adopted by the deoxidation membrane is: gas purge, negative pressure suction or a combination of gas purge and negative pressure suction.

[0019] Preferably, in the MBR-MD coupled membrane: the membrane purge aeration device aerates the membrane fibers through the aeration pipe to shake and flush the membrane fiber surface; the aperture of the perforated tube is preferably 3 to 8 mm

[0020] Preferably, the suspended filler is a spherical suspended filler, the specification of the ultrafine grid is preferably 1-5 mm, and the aperture of the microporous aeration disk is preferably 0.22-100 μm.

[0021] Preferably, the inner diameter of the deoxygenation membrane in the MBR-MD coupling membrane ranges from 0.1 to 0.3 mm, and the outer diameter ranges from 0.2 to 0.4 mm; the inner diameter of the MBR membrane ranges from 0.8 to 1.1 mm, and the outer diameter ranges from 0.9 to 1.2 mm.

[0022] The present invention provides an OMA / A denitrification and phosphorus removal method based on an MBR-MD coupling membrane, comprising:

[0023] After being filtered through ultra-fine screens, the sewage flows into the aerobic tank and the switchable anaerobic / anoxic tank in proportion;

[0024] Part of the sewage undergoes nitrification reaction under the action of aerobic nitrifying bacteria in the aerobic tank to convert ammonia nitrogen into nitrate nitrogen and nitrite nitrogen, and the digestate flows into the MBR-MD coupling membrane;

[0025] The nitrified liquid is filtered through the outer MBR membrane and then enters the inner layer. Under the action of the inner deoxygenation membrane, the gas molecules are pumped to the microporous aeration disk of the aerobic tank, and the deoxygenated nitrified liquid is pumped into the anaerobic / anoxic tank.

[0026] The other part of the sewage enters the anaerobic / anoxic tank to provide carbon source and phosphorus for the denitrifying polyphosphate bacteria. Under anaerobic conditions, the denitrifying polyphosphate bacteria absorb the carbon source, release phosphorus and obtain energy at the same time; when the deoxygenated nitrification liquid enters, the denitrifying polyphosphate bacteria use nitrate nitrogen / nitrite nitrogen as electron acceptors under anoxic conditions, and use the energy obtained under anaerobic conditions to reduce nitrate nitrogen / nitrite nitrogen to nitrogen gas while absorbing phosphorus, thereby achieving simultaneous denitrification and phosphorus removal.

[0027] Preferably, the switchable anaerobic / anoxic tank is specifically controlled by the inflow time of the deoxygenated nitrification liquid to achieve the switching between the anaerobic and anoxic environments: the anaerobic / anoxic zone has no aeration device, and before the deoxygenated nitrification liquid flows in, the reaction tank has no molecular oxygen and no combined oxygen, and is an anaerobic environment. After the deoxygenated nitrification liquid flows in, the reaction tank becomes an anoxic environment as combined oxygen enters.

[0028] Preferably, the gas molecules are further pumped to the microporous aeration disk of the aerobic tank by: the gas molecules are pumped out / purged by the degassing vacuum pump under the action of negative pressure / partial pressure and collected into the gas collecting pipe, and then pumped to the microporous aeration disk of the aerobic tank;

[0029] The deoxygenated nitrification liquid is pumped into the anaerobic / anoxic tank. Specifically, the deoxygenated nitrification liquid is pumped into the anaerobic / anoxic tank by a water production vacuum pump.

[0030] Preferably, the hydraulic retention time of the aerobic tank is 6 to 10 hours; the hydraulic retention time of the other part of the sewage entering the anaerobic / anoxic tank is 2 to 4 hours; the hydraulic retention time of the deoxygenated nitrification liquid after entering the anaerobic / anoxic tank is 3 to 6 hours;

[0031] After the sewage is treated for nitrogen and phosphorus removal, the supernatant is discharged from the anaerobic / anoxic zone overflow.

[0032] Preferably, an extremely low oxygen negative pressure is formed inside the deoxygenation membrane by the combined action of the blower air intake and the degassing vacuum pump suction, and the oxygen molecules in the sewage are pressed into the deoxygenation membrane under the action of the higher oxygen partial pressure, completing the deoxygenation process.

[0033] Compared with the prior art, the present invention provides an OMA / A denitrification and phosphorus removal device based on an MBR-MD coupling membrane, comprising: a water inlet device; an ultrafine grid whose inlet is connected to the outlet of the water inlet device; the outlet of the ultrafine grid is respectively connected to an aerobic tank and a switchable anaerobic / anoxic tank; a microporous aeration disk arranged at the bottom of the aerobic tank; an MBR-MD coupling membrane whose inlet is connected to the outlet of the aerobic tank; the MBR-MD coupling membrane is connected to the switchable anaerobic / anoxic tank via a water production vacuum pump; the switchable anaerobic / anoxic tank is provided with a The MBR-MD coupled membrane comprises: a coupled membrane module, an air collecting pipe arranged at the lower part of the coupled membrane module, and a water collecting pipe arranged at the upper part of the coupled membrane module; the coupled membrane module comprises an MBR membrane and a deoxygenation membrane arranged inside the MBR membrane; a membrane purge aeration device arranged at the lower part of the air collecting pipe, a blower for blowing air to the coupled membrane module, a water production vacuum pump connected to the water collecting pipe, and the air collecting pipe is connected to the microporous aeration disk at the bottom of the aerobic tank through the degassing vacuum pump. The present invention places an aerobic pool in front, and aerobic microorganisms convert ammonia nitrogen in sewage into nitrate nitrogen and nitrite nitrogen, which then flows into the anaerobic / anoxic zone, and convert nitrate nitrogen and nitrite nitrogen into nitrogen gas through denitrification reaction. Therefore, the present invention does not need to denitrify by reflux, saves reflux equipment, and reduces system energy consumption; the present invention uses the principle of denitrification and phosphorus accumulation, and this reaction principle can maximize the utilization of the carbon source of the influent while achieving simultaneous denitrification and phosphorus removal, and places a deoxygenation membrane with a small diameter inside a filter membrane with a large diameter. Compared with the only interception and filtration function of the traditional MBR membrane module, the coupled membrane module has the functions of intercepting sludge, filtering produced water, deoxygenating nitrified liquid, and membrane purge aeration recycling. At the same time, due to the multi-membrane nested design of the coupled membrane module, the anti-pollution ability and tensile strength of the coupled membrane filaments are enhanced, so that it only requires less purge gas than the traditional MBR membrane and is not easy to break. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a process flow chart of OMA / A denitrification and phosphorus removal based on MBR-MD coupling membrane of the present invention;

[0035] Figure 2 It is a schematic diagram of the OMA / A denitrification and phosphorus removal device based on the MBR-MD coupling membrane of the present invention;

[0036] Figure 3 It is a schematic diagram of the MBR-MD coupling membrane of the present invention. DETAILED DESCRIPTION

[0037] The present invention provides an OMA / A denitrification and dephosphorization device and method based on an MBR-MD coupled membrane. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It should be particularly pointed out that all similar replacements and modifications are obvious to those skilled in the art, and they all fall within the scope of protection of the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0038] The present invention provides an OMA / A denitrification and dephosphorization device based on an MBR-MD coupling membrane, comprising:

[0039] Water inlet device;

[0040] An ultra-fine grid having an inlet connected to an outlet of the water inlet device;

[0041] The ultra-fine grid outlets are connected to the aerobic tank and the switchable anaerobic / anoxic tank respectively;

[0042] A microporous aeration plate disposed at the bottom of the aerobic tank;

[0043] an MBR-MD coupling membrane whose inlet is connected to the outlet of the aerobic tank;

[0044] The MBR-MD coupled membrane is connected to the switchable anaerobic / anoxic tank via a water production vacuum pump;

[0045] The switchable anaerobic / anoxic tank is provided with a suspended filler;

[0046] The MBR-MD coupling membrane comprises:

[0047] A coupled membrane module, an air collecting pipe arranged at the lower part of the coupled membrane module, and a water collecting pipe arranged at the upper part of the coupled membrane module; the coupled membrane module comprises an MBR membrane and a deoxygenation membrane arranged inside the MBR membrane; a membrane purge aeration device arranged at the lower part of the air collecting pipe, a blower for blowing air to the coupled membrane module, a water production vacuum pump connected to the water collecting pipe, and the air collecting pipe is connected to the microporous aeration disk at the bottom of the aerobic tank through the degassing vacuum pump.

[0048] The OMA / A denitrification and dephosphorization device based on MBR-MD coupling membrane provided by the present invention comprises a water inlet device.

[0049] The present invention does not limit the water inlet device, and it can be any sewage inlet channel.

[0050] The OMA / A denitrification and dephosphorization device based on the MBR-MD coupling membrane provided by the present invention comprises an ultra-fine grid whose inlet is connected to the outlet of the water inlet device.

[0051] The ultra-fine grid of the present invention has a specific specification of 1 to 5 mm.

[0052] The ultrafine grid of the present invention has a filtering function. After being filtered through the ultrafine grid, the sewage flows into the aerobic zone and the anaerobic / anoxic zone in appropriate proportions.

[0053] The ultra-fine screen outlets are connected to the aerobic tank and the switchable anaerobic / anoxic tank respectively.

[0054] The ratio of sewage flowing into the aerobic tank and the switchable anaerobic / anoxic tank is preferably 7:1 to 1:1.

[0055] The OMA / A denitrification and dephosphorization device based on the MBR-MD coupling membrane provided by the present invention comprises a microporous aeration disk arranged at the bottom of the aerobic tank.

[0056] The preferred pore size of the microporous aeration disk of the present invention is 0.22-100 μm.

[0057] The aerobic pool of the present invention is an aerobic zone, and a microporous aeration plate is arranged at the bottom to supply oxygen. The sewage flowing into the aerobic zone undergoes nitrification reaction under the action of aerobic nitrifying bacteria to convert ammonia nitrogen into nitrate nitrogen and nitrite nitrogen.

[0058] The OMA / A denitrification and dephosphorization device based on the MBR-MD coupling membrane provided by the present invention comprises an MBR-MD coupling membrane whose inlet is connected to the outlet of the aerobic tank.

[0059] The MBR-MD coupling membrane of the present invention comprises:

[0060] A coupled membrane module, an air collecting pipe arranged at the lower part of the coupled membrane module, and a water collecting pipe arranged at the upper part of the coupled membrane module; the coupled membrane module comprises an MBR membrane and a deoxygenation membrane arranged inside the MBR membrane; a membrane purge aeration device arranged at the lower part of the air collecting pipe, a blower for blowing air to the coupled membrane module, a water production vacuum pump connected to the water collecting pipe, and the air collecting pipe is connected to the microporous aeration disk at the bottom of the aerobic tank through the degassing vacuum pump.

[0061] Specifically, the MBR-MD coupling membrane of the present invention includes a coupling membrane module.

[0062] The MBR-MD coupling membrane comprises an air collecting pipe arranged at the lower part of the coupling membrane module; and a water collecting pipe arranged at the upper part of the coupling membrane module. The present invention does not limit the specifications of the air collecting pipe and the water collecting pipe, and preferably the length thereof is consistent with the width of the coupling membrane.

[0063] The coupled membrane module of the present invention comprises an MBR membrane and a deoxidation membrane arranged inside the MBR membrane.

[0064] The coupled membrane module is the core of the coupled membrane system. It consists of a deoxygenation membrane with a smaller diameter placed inside the MBR membrane with a larger diameter to form a double-layer composite membrane.

[0065] Among them, the inner diameter size range of the deoxygenation membrane filament in the MBR-MD coupling membrane is 0.1-0.3mm, which can be 0.1mm, 0.2mm, 0.3mm or any value between the above two; the outer diameter size range is 0.2-0.4mm; it can be 0.2mm, 0.3mm, 0.4mm or any value between the above two; the inner diameter size range of the MBR membrane filament is 0.8-1.1mm, which can be 0.8mm, 0.9mm, 1.0mm, 1.1mm or any value between the above two; the outer diameter size range is 0.9-1.2mm, which can be 0.9mm, 1.0mm, 1.1mm, 1.2mm or any value between the above two.

[0066] The sewage of the present invention enters the inner layer of the MBR membrane after being filtered through the MBR membrane. The filtered sewage contacts the MD deoxygenation membrane in the inner layer of the MBR membrane. The gas molecules in the sewage are extracted / blown out by the degassing vacuum pump under the action of negative pressure / partial pressure and collected into the bottom gas collecting pipe. The gas collecting pipe is connected to the microporous aeration plate in the aerobic zone, and the deoxygenated sewage is pumped into the anaerobic / anoxic zone by the water production vacuum pump.

[0067] The double-layer composite membrane of the present invention has four main functions, namely, separation of mud and water, deoxygenation of nitrification liquid, enhanced membrane cleaning effect, and membrane purge aeration and reuse.

[0068] The functions of the outer MBR membrane are: (1) intercepting sludge and retaining nitrifying bacteria in the aerobic zone; (2) pre-treating the deoxygenation membrane to prevent suspended particles from clogging the deoxygenation membrane; and (3) the purge aeration of the MBR membrane provides oxygen for the microorganisms in the aerobic zone during the intermittent period of the microporous aeration device in the aerobic zone.

[0069] The functions of the inner deoxygenation membrane are as follows: (1) Remove dissolved oxygen from the nitrification liquid to prevent the nitrification liquid from entering the anaerobic / anoxic zone and destroying the original anaerobic / anoxic environment; (2) Transport the removed oxygen-rich air to the microporous aeration device in the aerobic zone to provide oxygen for aerobic microorganisms; (3) Use the vibration caused by purging and suction during deoxygenation to drive the outer MBR membrane to vibrate. During deoxygenation, the purged air recoils from the inside of the MBR membrane to the outside of the membrane. The membrane vibration and air recoil are beneficial to alleviate membrane pollution, reduce membrane purging aeration, and thus reduce aeration energy consumption; (4) The inner deoxygenation membrane is equivalent to adding an inner lining to the outer filter membrane, which strengthens the tensile strength of the membrane fibers and can effectively avoid the occurrence of "broken fibers".

[0070] The present invention does not simply stack and combine membrane modules with different functions, but places membrane filaments with smaller diameters inside membrane filaments with larger diameters according to the diameter of the membrane, and selects the combination order of different membranes according to the function of the membrane. Compared with the traditional superposition coupling method of membrane modules, the coupled membrane module in the form of multi-layer membrane nesting is smaller in size. The present invention couples the deoxygenation membrane with the filter membrane, and the deoxygenation membrane with smaller diameter is placed inside the filter membrane. The deoxygenation membrane can be in the form of a hollow fiber membrane and a flat membrane. Three deoxygenation methods such as gas purging, negative pressure suction, and a combination of gas purging and negative pressure suction can be used. The filter membrane can be in the form of a hollow fiber membrane and a flat membrane, and negative pressure suction is used for filtration. The outer filter membrane filters out suspended particles, plays a pretreatment role for the inner deoxygenation membrane, and avoids fouling of the deoxygenation membrane. During the deoxygenation process, the inner deoxygenation membrane drives the outer filter membrane to shake and perform gas backwashing, which slows down the pollution rate of the outer membrane filaments.

[0071] The deoxygenation membrane is an organic membrane or an inorganic membrane; the deoxygenation membrane is a hollow fiber membrane or a flat membrane; the preferred pore size of the deoxygenation membrane is 0.01-0.03 μm; it can be 0.01 μm, 0.02 μm or 0.03 μm; the preferred pore size of the MBR membrane is 0.03-0.4 μm; preferably 0.05-0.35 μm.

[0072] The deoxygenation methods adopted by the deoxygenation membrane described in the present invention are: gas purging, negative pressure suction, or a combination of gas purging and negative pressure suction. Aerated stripping mainly uses nitrogen or compressed air for purging to reduce the oxygen partial pressure inside the membrane, so that the gas in the liquid phase is transferred from the liquid phase to the gas phase, and the inlet pressure is generally controlled below 0.7kPa; the vacuum suction method is to create a partial pressure gradient between the liquid phase and the gas phase. The vacuum causes the dissolved oxygen to diffuse from the inside of the liquid to the vacuum side, and the oxygen is sucked and discharged through the vacuum pump. The degree of vacuum directly affects the removal efficiency. The greater the vacuum degree, the lower the gas content of the outlet liquid. Generally, the vacuum degree is controlled at 150mbar-50mbar during use. Vacuum suction-assisted aerated stripping combines the above two methods and can be adjusted according to actual usage.

[0073] The designed processing capacity of the deoxidation membrane used in the present invention is 20L / m 2 / h~120L / m 2 / h, the designed processing capacity of the filtration membrane is 15L / m 2 / h~30L / m 2 / h; therefore, in order to maximize the combined use of the processing capacity of the deoxygenation membrane and the filtration membrane, ordinary filtration membranes can be used for the membrane fibers arranged close to the outside, and MBR-MD coupling membranes can be used for the membrane fibers arranged on the inside.

[0074] The MBR-MD coupling membrane of the present invention comprises a membrane purge aeration device arranged at the lower part of the gas collecting pipe; the membrane purge aeration device is a perforated tube. The preferred length of the perforated tube of the present invention is consistent with the width of the coupling membrane module, and the preferred pore size of the perforated tube is 3-8 mm.

[0075] The MBR-MD coupled membrane of the present invention comprises a blower for blowing air to the coupled membrane module.

[0076] The present invention does not limit the model and specifications of the blower, which are well known to those skilled in the art.

[0077] The MBR-MD coupling membrane of the present invention comprises a water production vacuum pump connected to the water collecting pipe; the gas collecting pipe is connected to the microporous aeration disk at the bottom of the aerobic tank through a degassing vacuum pump.

[0078] In the MBR-MD coupled membrane: the membrane purge aeration device aerates the membrane fibers through the gas collecting pipe to shake and flush the membrane fiber surface. In this process, a large amount of oxygen will enter the sewage.

[0079] After being filtered by the outer MBR membrane, the sewage enters the inner layer, flows upward under the suction of the water production vacuum pump, and is collected in the water collection pipe. During the sewage flow process, it passes through the inner deoxygenation membrane. The inside of the deoxygenation membrane forms an extremely low oxygen negative pressure under the combined action of the blower air intake and the degassing vacuum pump suction, and the oxygen molecules in the sewage are pressed into the deoxygenation membrane under the action of the higher oxygen partial pressure, completing the sewage deoxygenation process, and the collected oxygen-rich air flows downward to the gas collection pipe. The deoxygenated nitrification liquid in the water collection pipe is pumped into the anaerobic / anoxic zone by the water production vacuum pump, and the oxygen-rich air in the gas collection pipe is pumped into the microporous aeration device by the degassing vacuum pump.

[0080] The MBR-MD coupling membrane of the present invention is connected to a switchable anaerobic / anoxic tank via a water production vacuum pump. The switchable anaerobic / anoxic tank is provided with a suspended filler.

[0081] The suspended filler of the present invention is preferably a spherical suspended filler.

[0082] The sewage entering the anaerobic / anoxic zone provides a carbon source for denitrifying polyphosphate bacteria. Since there is no aeration device in the anaerobic / anoxic zone, the denitrifying polyphosphate bacteria release phosphorus to obtain energy under completely anaerobic conditions. Then, the deoxygenated nitrification liquid is pumped into the anaerobic / anoxic zone with a vacuum pump. The nitrate nitrogen / nitrite nitrogen in the nitrification liquid changes the anaerobic / anoxic zone from an anaerobic environment to an anoxic environment. The carbon source flowing in with the nitrification liquid enables the denitrifying polyphosphate bacteria to use nitrate nitrogen / nitrite nitrogen as an electron acceptor, and reduce nitrate nitrogen / nitrite nitrogen to nitrogen gas while absorbing phosphorus, completing the synchronous denitrification and phosphorus removal process. After the sewage is treated with denitrification and phosphorus removal, the supernatant overflows and is discharged from the anaerobic / anoxic zone.

[0083] The present invention performs nitrification reaction in the aerobic zone and denitrification and phosphorus removal in the anaerobic / anoxic zone, supplements the carbon source required for phosphorus release and denitrification and phosphorus accumulation process by diverting the incoming water, realizes denitrification and phosphorus removal under the condition of no reflux, and saves the energy consumption required for reflux. Based on the principle of denitrification and phosphorus accumulation, nitrate nitrogen and nitrite nitrogen are injected under anaerobic conditions, and suspended fillers are added to the reaction tank at the same time, which is convenient for the enrichment of denitrification and phosphorus accumulation bacteria. Denitrification and phosphorus accumulation bacteria realize nitrogen removal while accumulating phosphorus, realizing "one carbon for two uses", greatly saving carbon sources, and avoiding the situation in which the competition between phosphorus accumulation bacteria and denitrifying bacteria for carbon sources in anaerobic environment affects the denitrification and phosphorus removal effect in the traditional AAO process.

[0084] Figure 1 This is a process flow chart of OMA / A denitrification and phosphorus removal based on MBR-MD coupling membrane of the present invention;

[0085] Figure 2 It is a schematic diagram of the OMA / A denitrification and phosphorus removal device based on the MBR-MD coupling membrane of the present invention;

[0086] Figure 3 It is a schematic diagram of the MBR-MD coupling membrane of the present invention.

[0087] Among them, 1 is a water inlet device, 2 is an ultrafine grid, 3 is an aerobic tank, 4 is a switchable anaerobic / anoxic tank, 5 is a microporous aeration disk; 6 is a degassing vacuum pump; 7 is a membrane purge aeration device (perforated pipe); 8 is an MBR-MD coupling membrane; 9 is a blower; 10 is a water production vacuum pump, 11 is a suspended filler, 12 is a water collecting pipe, 13 is a degassing pipe, 14 is a deoxygenation membrane, and 15 is an MBR membrane.

[0088] The present invention provides an OMA / A denitrification and phosphorus removal method based on an MBR-MD coupling membrane, comprising:

[0089] After being filtered through ultra-fine screens, the sewage flows into the aerobic tank and the switchable anaerobic / anoxic tank in proportion;

[0090] Part of the sewage undergoes nitrification reaction under the action of aerobic nitrifying bacteria in the aerobic tank to convert ammonia nitrogen into nitrate nitrogen and nitrite nitrogen, and the digestate flows into the MBR-MD coupling membrane;

[0091] The nitrified liquid is filtered through the outer MBR membrane and then enters the inner layer. Under the action of the inner deoxygenation membrane, the gas molecules are pumped to the microporous aeration disk of the aerobic tank, and the deoxygenated nitrified liquid is pumped into the anaerobic / anoxic tank.

[0092] The other part of the sewage enters the anaerobic / anoxic tank to provide carbon source and phosphorus for the denitrifying polyphosphate bacteria. Under anaerobic conditions, the denitrifying polyphosphate bacteria absorb the carbon source, release phosphorus and obtain energy at the same time; when the deoxygenated nitrification liquid enters, the denitrifying polyphosphate bacteria use nitrate nitrogen / nitrite nitrogen as electron acceptors under anoxic conditions, and use the energy obtained under anaerobic conditions to reduce nitrate nitrogen / nitrite nitrogen to nitrogen gas while absorbing phosphorus, thereby achieving simultaneous denitrification and phosphorus removal.

[0093] The invention discloses an OMA / A denitrification and phosphorus removal method based on MBR-MD coupling membrane. Firstly, sewage is filtered through an ultrafine grid and then flows into an aerobic tank and a switchable anaerobic / anoxic tank respectively in proportion.

[0094] After being filtered through the ultra-fine grid, the sewage flows into the aerobic zone and the anaerobic / anoxic zone in appropriate proportions, preferably 4:1 to 1:1.

[0095] Part of the sewage undergoes nitrification reaction under the action of aerobic nitrifying bacteria in the aerobic tank to convert ammonia nitrogen into nitrate nitrogen and nitrite nitrogen, and the digestate flows into the MBR-MD coupling membrane.

[0096] A microporous aeration plate is installed at the bottom of the aerobic zone to supply oxygen. The sewage flowing into the aerobic zone undergoes nitrification reaction under the action of aerobic nitrifying bacteria to convert ammonia nitrogen into nitrate nitrogen and nitrite nitrogen.

[0097] The nitrified liquid is filtered through the outer MBR membrane and enters the inner layer. Under the action of the inner deoxygenation membrane, the gas molecules are then pumped to the microporous aeration disk of the aerobic tank, and the deoxygenated nitrified liquid is pumped into the anaerobic / anoxic tank.

[0098] The preferred embodiment is as follows: the nitrification liquid enters the inner layer of the MBR membrane after being filtered through the MBR membrane, the filtered sewage contacts the MD deoxygenation membrane in the inner layer of the MBR membrane, and the gas molecules in the sewage are extracted / purged by the degassing vacuum pump under the action of negative pressure / partial pressure and collected into the bottom gas collecting pipe, and the gas collecting pipe is connected to the microporous aeration plate in the aerobic zone.

[0099] The sewage enters the inner layer of the MBR membrane after being filtered through the MBR membrane. The filtered sewage contacts the MD deoxygenation membrane in the inner layer of the MBR membrane. The gas molecules in the sewage are extracted / blown out by the degassing vacuum pump under the action of negative pressure / partial pressure and collected into the bottom gas collecting pipe. The gas collecting pipe is connected to the microporous aeration plate in the aerobic zone, and the deoxygenated sewage is pumped into the anaerobic / anoxic zone by the water production vacuum pump.

[0100] The coupled membrane module of the present invention is the core of the coupled membrane system. It is composed of a deoxygenation membrane with a smaller diameter placed inside a MBR membrane with a larger diameter to form a double-layer composite membrane. The blower supplies air to the membrane purge device of the coupled membrane module. The membrane purge device aerates through a perforated tube to shake the membrane wire and flush the membrane wire surface. In this process, a large amount of oxygen will enter the sewage. After being filtered by the outer MBR membrane, the sewage enters the inner layer, flows upward under the suction of the water production vacuum pump, and is collected in the water collection pipe. The sewage flows through the inner deoxygenation membrane. The deoxygenation membrane forms an extremely low oxygen negative pressure under the combined action of the blower air intake and the degassing vacuum pump suction. The oxygen molecules in the sewage are pressed into the deoxygenation membrane under the action of a higher oxygen partial pressure, completing the sewage deoxygenation process, and the collected oxygen-rich air flows downward to the gas collection pipe. The deoxygenated nitrification liquid in the water collection pipe is pumped into the anaerobic / anoxic zone by the water production vacuum pump, and the oxygen-rich air in the gas collection pipe is pumped into the microporous aeration device by the degassing vacuum pump.

[0101] The other part of the sewage enters the anaerobic / anoxic tank to provide carbon source and phosphorus for the denitrifying polyphosphate bacteria. Under anaerobic conditions, the denitrifying polyphosphate bacteria absorb the carbon source, release phosphorus and obtain energy at the same time; when the deoxygenated nitrification liquid enters, the denitrifying polyphosphate bacteria use nitrate nitrogen / nitrite nitrogen as electron acceptors under anoxic conditions, and use the energy obtained under anaerobic conditions to reduce nitrate nitrogen / nitrite nitrogen to nitrogen gas while absorbing phosphorus, thereby achieving simultaneous denitrification and phosphorus removal.

[0102] The switchable anaerobic / anoxic tank of the present invention specifically controls the switching between anaerobic and anoxic environments by the inflow time of the deoxygenated nitrification liquid: the anaerobic / anoxic zone has no aeration device, and before the deoxygenated nitrification liquid flows in, the reaction tank has no molecular oxygen and no combined oxygen, and is an anaerobic environment. After the deoxygenated nitrification liquid flows in, the reaction tank becomes an anoxic environment as combined oxygen enters.

[0103] The anaerobic / anoxic zone has no aeration device. Before the nitrification liquid flows in, the reaction pool has no molecular oxygen or combined oxygen, and is an anaerobic environment. When the nitrification liquid flows in, with the entry of combined oxygen (nitrate nitrogen and nitrite nitrogen), the reaction pool becomes an anoxic environment. Its beneficial effects are as follows: (1) The anoxic / anaerobic zone does not need to switch the environment through aeration like the traditional SBR process, saving aeration energy consumption. The environment without molecular oxygen can avoid the competition of aerobic heterotrophic bacteria for carbon sources, which is conducive to the enrichment of denitrifying polyphosphate bacteria; (2) The anaerobic and anoxic reaction processes are completely separated by water distribution, which is conducive to the enrichment of denitrifying polyphosphate bacteria: the anaerobic / anoxic zone water inflow is in two stages. The first stage is the system diversion water inflow, which provides phosphorus and carbon sources for the denitrifying polyphosphate bacteria to release phosphorus in the anaerobic environment. The second stage is the nitrification liquid water inflow, which provides nitrate nitrogen / nitrite nitrogen and carbon sources for the denitrifying polyphosphate bacteria to accumulate phosphorus in the anoxic environment. Since there is no nitrate nitrogen / nitrite nitrogen in the reaction tank in the first stage, the denitrifying bacteria cannot compete with the denitrifying polyphosphate bacteria for carbon sources in this stage, making the denitrifying polyphosphate bacteria dominant.

[0104] The sequence of the present invention indicates that the anaerobic / anoxic zone changes the anaerobic and anoxic environment of the reaction tank by the inflow of nitrification liquid. This design is conducive to the enrichment of denitrifying polyphosphate bacteria and saves the energy consumption required for aeration. In addition, suspended fillers are added to the anaerobic / anoxic zone to enrich the denitrifying polyphosphate bacteria on the fillers, and the denitrifying polyphosphate bacteria are strengthened. The status of the bacterial community can also reduce the concentration of suspended sludge in the pool, which is convenient for the supernatant to overflow and produce water.

[0105] The deoxygenated nitrification liquid is pumped into the anaerobic / anoxic tank in the present invention, specifically: the deoxygenated nitrification liquid is pumped into the anaerobic / anoxic tank by a water production vacuum pump.

[0106] The sewage entering the anaerobic / anoxic zone provides a carbon source for denitrifying polyphosphate bacteria. Since there is no aeration device in the anaerobic / anoxic zone, the denitrifying polyphosphate bacteria release phosphorus to obtain energy under completely anaerobic conditions. Then, the deoxygenated nitrification liquid is pumped into the anaerobic / anoxic zone with a vacuum pump. The nitrate nitrogen / nitrite nitrogen in the nitrification liquid changes the anaerobic / anoxic zone from an anaerobic environment to an anoxic environment. The carbon source flowing in with the nitrification liquid enables the denitrifying polyphosphate bacteria to use nitrate nitrogen / nitrite nitrogen as an electron acceptor, and reduce nitrate nitrogen / nitrite nitrogen to nitrogen gas while absorbing phosphorus, completing the synchronous denitrification and phosphorus removal process. After the sewage is treated with denitrification and phosphorus removal, the supernatant overflows and is discharged from the anaerobic / anoxic zone.

[0107] The hydraulic retention time of the aerobic tank is 6 to 10 hours; the hydraulic retention time of the other part of the sewage entering the anaerobic / anoxic tank is 2 to 4 hours; the hydraulic retention time of the deoxygenated nitrification liquid after entering the anaerobic / anoxic tank is 3 to 6 hours;

[0108] The present invention provides an OMA / A denitrification and phosphorus removal device based on an MBR-MD coupling membrane, comprising: a water inlet device; an ultrafine grid whose inlet is connected to the outlet of the water inlet device; the outlet of the ultrafine grid is respectively connected to an aerobic tank and a switchable anaerobic / anoxic tank; a microporous aeration disk arranged at the bottom of the aerobic tank; an MBR-MD coupling membrane whose inlet is connected to the outlet of the aerobic tank; the MBR-MD coupling membrane is connected to the switchable anaerobic / anoxic tank via a water production vacuum pump; the switchable anaerobic / anoxic tank is provided with a suspended Filler; the MBR-MD coupled membrane comprises: a coupled membrane module, an air collecting pipe arranged at the lower part of the coupled membrane module, and a water collecting pipe arranged at the upper part of the coupled membrane module; the coupled membrane module comprises an MBR membrane and a deoxygenation membrane arranged inside the MBR membrane; a membrane purge aeration device arranged at the lower part of the air collecting pipe, a blower for blowing air to the coupled membrane module, a water production vacuum pump connected to the water collecting pipe, and the air collecting pipe is connected to the microporous aeration disk at the bottom of the aerobic tank through the degassing vacuum pump. The present invention places an aerobic pool in front, and aerobic microorganisms convert ammonia nitrogen in sewage into nitrate nitrogen and nitrite nitrogen, which then flows into the anaerobic / anoxic zone, and convert nitrate nitrogen and nitrite nitrogen into nitrogen gas through denitrification reaction. Therefore, the present invention does not need to denitrify by reflux, saves reflux equipment, and reduces system energy consumption; the present invention uses the principle of denitrification and phosphorus accumulation, and this reaction principle can maximize the utilization of the carbon source of the influent while achieving simultaneous denitrification and phosphorus removal, and places a deoxygenation membrane with a small diameter inside a filter membrane with a large diameter. Compared with the only interception and filtration function of the traditional MBR membrane module, the coupled membrane module has the functions of intercepting sludge, filtering produced water, deoxygenating nitrified liquid, and membrane purge aeration recycling. At the same time, due to the multi-membrane nested design of the coupled membrane module, the anti-pollution ability and tensile strength of the coupled membrane filaments are enhanced, so that it only requires less purge gas than the traditional MBR membrane and is not easy to break.

[0109] In order to further illustrate the present invention, an OMA / A denitrification and phosphorus removal device and method based on an MBR-MD coupling membrane provided by the present invention are described in detail below in conjunction with embodiments.

[0110] Example 1

[0111] The OMA / A denitrification and phosphorus removal device based on MBR-MD coupling membrane comprises: a water inlet device; a 3mm ultrafine grid whose inlet is connected to the outlet of the water inlet device; the outlet of the ultrafine grid is respectively connected to the aerobic tank and the switch anaerobic / anoxic tank; a 50μm microporous aeration disk arranged at the bottom of the aerobic tank; an MBR-MD coupling membrane whose inlet is connected to the outlet of the aerobic tank; the MBR-MD coupling membrane is connected to the switch anaerobic / anoxic tank through a water production vacuum pump; the switch anaerobic / anoxic tank is provided with suspended fillers; the MBR-MD coupling membrane comprises: a coupling membrane module, a gas collecting pipe arranged at the lower part of the coupling membrane module, and a A water collecting pipe at the upper part of the coupled membrane module; the coupled membrane module comprises an MBR membrane (the inner diameter of the MBR membrane thread used is 0.8 mm and the outer diameter is 0.9 mm) and a deoxygenation membrane arranged inside the MBR membrane (the inner diameter of the deoxygenation membrane thread used is 0.15 mm and the outer diameter is 0.25 mm); a membrane purge aeration device (using a perforated aeration tube with a pore size of 5 mm) is arranged at the lower part of the coupled membrane module, a blower for blowing air to the coupled membrane module, and a water production vacuum pump connected to the gas collecting pipe, and the gas collecting pipe is connected to the microporous aeration disk at the bottom of the aerobic tank through the degassing vacuum pump.

[0112] After being filtered by the ultra-fine grid, the sewage flows into the aerobic zone and the anaerobic / anoxic zone in a ratio of 7:1, with a total residence time of 7h: in the aerobic zone, the membrane module is perforated for aeration and oxygen is supplied, and the sewage flowing into the aerobic zone undergoes nitrification reaction under the action of aerobic nitrifying bacteria to convert ammonia nitrogen into nitrate nitrogen and nitrite nitrogen. After being filtered by the MBR membrane, the sewage enters the inner layer of the MBR membrane. The filtered sewage contacts the MD deoxygenation membrane in the inner layer of the MBR membrane. The oxygen in the sewage is extracted / purged by the degassing vacuum pump under the action of negative pressure / partial pressure and collected to the bottom gas collecting pipe. The gas collecting pipe is connected to the microporous aeration plate in the aerobic zone. At this time, the recovered oxygen-rich air supplies oxygen to the aerobic zone through the microporous aeration plate, and the deoxygenated sewage is pumped into the anaerobic / anoxic zone by the water production vacuum pump. The sewage enters the anaerobic / anoxic zone twice. The first time is that the untreated sewage enters the anaerobic / anoxic zone directly in an appropriate proportion. The hydraulic retention time of this stage is 3 hours. The sewage provides a carbon source for denitrifying polyphosphate bacteria. Since there is no aeration device in the anaerobic / anoxic zone, the denitrifying polyphosphate bacteria release phosphorus and synthesize PHA / PHB and store it in the body under completely anaerobic conditions. The second time is that the vacuum pump pumps the sewage that has been treated with nitrification and deoxygenation into the anaerobic / anoxic zone. The hydraulic retention time of this stage is 4 hours. The nitrate nitrogen / nitrite nitrogen in the nitrification liquid changes the anaerobic / anoxic zone from an anaerobic environment to an anoxic environment. The denitrifying polyphosphate bacteria use nitrate nitrogen / nitrite nitrogen as an electron acceptor and use the PHA / PHB stored in the body as energy. While absorbing phosphorus, the nitrate nitrogen / nitrite nitrogen is reduced to nitrogen gas, completing the simultaneous denitrification and phosphorus removal. After a series of treatments, the sewage is discharged from the anaerobic / anoxic zone.

[0113] The test water was taken from the domestic sewage of a municipal sewage treatment plant in Fujian. The main water quality indicators were: COD Cr =344mg / L, NH3-N=47mg / L, TN=51mg / L, TP=3.2mg / L. The above indicators are all measured according to the standard method in "Water and Wastewater Monitoring and Analysis Methods (Fourth Edition)".

[0114] When the device of this embodiment is in use, the sewage is pumped into the aerobic zone and the anaerobic / anoxic zone respectively through the water inlet pump, the water inlet ratio is 7:1, and the total hydraulic retention time of the sewage in the reactor is 7h. It is a sequencing batch reactor: the perforated aeration pipe below the membrane group is aerated for the aerobic nitrification reaction of aerobic nitrifying bacteria in the aerobic zone for the first 3h, and during these 3h, the sewage entering the anaerobic / anoxic zone provides a carbon source for denitrifying polyphosphate bacteria under completely anaerobic conditions to release phosphorus anaerobically and synthesize PHA / PHB. After 3h, the vacuum pump of the MBR-MD coupling membrane system is started, and the oxygen in the oxygen-rich sewage near the membrane group is removed and recycled and then pumped into the microporous aeration disk to supply oxygen to the aerobic zone, and the deoxygenated sewage is pumped into the anaerobic / anoxic zone by the produced water vacuum pump, and the process lasts for 4h. After the deoxygenated nitrification liquid enters the anaerobic / anoxic zone, it brings in nitrate and nitrite. The denitrifying polyphosphate bacteria in the anaerobic / anoxic zone use nitrate nitrogen and nitrite nitrogen as electron acceptors and the PHA / PHB stored in the body as a carbon source (electron donor) to carry out simultaneous denitrification and phosphorus removal.

[0115] According to the above implementation steps, after 2 months of domestication and cultivation, the effluent COD Cr The average concentrations of NH3-N, TN and TP were 26.7mg / L, 1.3mg / L, 7.9mg / L and 0.4mg / L respectively. Since the water is finally produced by the anaerobic / anoxic zone, the denitrification phosphorus removal process is easy to control, so the system has a good removal effect on TN and TP, meeting the A standard requirements of the first level of the "Urban Wastewater Discharge Standard" (GB18918-2002). In addition, since a special aeration and oxygen supply device is omitted, the gas-water ratio of the system is 8:1, which saves more than half of the aeration volume compared to the gas-water ratio of 20:1 to 30:1 of the traditional MBR process, and the system omits the reflux device, so the energy consumption per ton of water treatment in the system (0.38kWh / t) is lower than that of the traditional MBR process (0.9 to 1.3kWh / t).

[0116] Example 2

[0117] The OMA / A denitrification and phosphorus removal device based on MBR-MD coupling membrane comprises: a water inlet device; a 1 mm ultrafine grid whose inlet is connected to the outlet of the water inlet device; the outlet of the ultrafine grid is respectively connected to the aerobic tank and the switch anaerobic / anoxic tank; a 0.22 μm microporous aeration disk arranged at the bottom of the aerobic tank; an MBR-MD coupling membrane whose inlet is connected to the outlet of the aerobic tank; the MBR-MD coupling membrane is connected to the switch anaerobic / anoxic tank through a water production vacuum pump; the switch anaerobic / anoxic tank is provided with suspended fillers; the MBR-MD coupling membrane comprises: a coupling membrane module, a gas collecting pipe arranged at the lower part of the coupling membrane module, a device A water collecting pipe is placed on the upper part of the coupled membrane module; the coupled membrane module includes an MBR membrane (the inner diameter of the MBR membrane thread used is 1.0 mm, and the outer diameter ranges from 1.2 mm) and a deoxygenation membrane arranged inside the MBR membrane (the inner diameter of the deoxygenation membrane thread used is 0.2 mm, and the outer diameter ranges from 0.25 mm); a membrane purge aeration device (using a perforated aeration tube with a pore size of 8 mm) is arranged at the lower part of the coupled membrane module, a blower for blowing air to the coupled membrane module, and a water production vacuum pump connected to the gas collecting pipe, and the gas collecting pipe is connected to the microporous aeration disk at the bottom of the aerobic tank through the degassing vacuum pump.

[0118] After being filtered by ultra-fine grids, the sewage flows into the aerobic zone and the anaerobic / anoxic zone in a ratio of 4:1, with a total residence time of 8 hours: in the aerobic zone, the membrane module is perforated for aeration and oxygen is supplied, and the sewage flowing into the aerobic zone undergoes nitrification reaction under the action of aerobic nitrifying bacteria to convert ammonia nitrogen into nitrate nitrogen and nitrite nitrogen. After being filtered by the MBR membrane, the sewage enters the inner layer of the MBR membrane. The filtered sewage contacts the MD deoxygenation membrane in the inner layer of the MBR membrane. The oxygen in the sewage is extracted / purged by the degassing vacuum pump under the action of negative pressure / partial pressure and collected to the bottom gas collecting pipe. The gas collecting pipe is connected to the microporous aeration plate in the aerobic zone. At this time, the recovered oxygen-rich air supplies oxygen to the aerobic zone through the microporous aeration plate, and the deoxygenated sewage is pumped into the anaerobic / anoxic zone by the water production vacuum pump. The sewage enters the anaerobic / anoxic zone twice. The first time is that the untreated sewage enters the anaerobic / anoxic zone directly in an appropriate proportion. The hydraulic retention time of this stage is 4 hours. The sewage provides a carbon source for denitrifying polyphosphate bacteria. Since there is no aeration device in the anaerobic / anoxic zone, the denitrifying polyphosphate bacteria release phosphorus and synthesize PHA / PHB and store it in the body under completely anaerobic conditions. The second time is that the vacuum pump pumps the sewage that has been treated with nitrification and deoxygenation into the anaerobic / anoxic zone. The hydraulic retention time of this stage is 4 hours. The nitrate nitrogen / nitrite nitrogen in the nitrification liquid changes the anaerobic / anoxic zone from an anaerobic environment to an anoxic environment. The denitrifying polyphosphate bacteria use nitrate nitrogen / nitrite nitrogen as an electron acceptor and use the PHA / PHB stored in the body as energy. While absorbing phosphorus, they reduce nitrate nitrogen / nitrite nitrogen to nitrogen gas, completing simultaneous denitrification and phosphorus removal. After a series of treatments, the sewage is discharged from the anaerobic / anoxic zone.

[0119] The test water was taken from the domestic sewage of a municipal sewage treatment plant in Fujian. The main water quality indicators were: COD Cr =289mg / L, NH3-N=51mg / L, TN=56mg / L, TP=4.5mg / L. The above indicators are all measured according to the standard method in "Water and Wastewater Monitoring and Analysis Methods (Fourth Edition)".

[0120] When the device of this embodiment is in use, the sewage is pumped into the aerobic zone and the anaerobic / anoxic zone respectively through the water inlet pump, the water inlet ratio is 4:1, and the total hydraulic retention time of the sewage in the reactor is 8 hours. It is a sequencing batch reactor: the perforated aeration tube below the membrane group is aerated in the first 4 hours to supply oxygen for the nitrification reaction of aerobic nitrifying bacteria in the aerobic zone, and in these 4 hours, the sewage entering the anaerobic / anoxic zone provides a carbon source for denitrifying polyphosphate bacteria under completely anaerobic conditions to release phosphorus anaerobically and synthesize PHA / PHB. After 4 hours, the vacuum pump of the MBR-MD coupling membrane system is started, and the oxygen in the sewage in the aerobic zone is removed and recycled and then pumped into the microporous aeration disk to supply oxygen to the aerobic zone, and the deoxygenated sewage is pumped into the anaerobic / anoxic zone. This process lasts for 4 hours. After the deoxygenated nitrification liquid enters the anaerobic / anoxic zone, it brings in nitrate and nitrite. The denitrifying polyphosphate bacteria in the anaerobic / anoxic zone use nitrate nitrogen and nitrite nitrogen as electron acceptors and the PHA / PHB stored in the body as a carbon source (electron donor) to carry out simultaneous denitrification and phosphorus removal.

[0121] According to the above implementation steps, after one month of domestication and cultivation, the effluent COD Cr The average concentrations of NH3-N, TN and TP were 20.6mg / L, 2.1mg / L, 6.6mg / L and 0.5mg / L respectively. Since the water is finally produced by the anaerobic / anoxic zone, the denitrification phosphorus removal process is easy to control, so the system has a good removal effect on TN and TP, meeting the A standard requirements of the first level of the "Urban Wastewater Discharge Standard" (GB18918-2002). In addition, since a special aeration and oxygen supply device is omitted, the gas-water ratio of the system is less than 9:1, which saves more than half of the aeration volume compared to the gas-water ratio of 20:1 to 30:1 of the traditional MBR process, and the system omits the reflux device, so the energy consumption per ton of water treatment in the system (0.46kWh / t) is lower than that of the traditional MBR process (0.9 to 1.3kWh / t).

[0122] Example 3

[0123] The OMA / A denitrification and phosphorus removal device based on MBR-MD coupling membrane comprises: a water inlet device; a 1 mm ultrafine grid whose inlet is connected to the outlet of the water inlet device; the outlet of the ultrafine grid is respectively connected to the aerobic tank and the switch anaerobic / anoxic tank; a 0.22 μm microporous aeration disk arranged at the bottom of the aerobic tank; an MBR-MD coupling membrane whose inlet is connected to the outlet of the aerobic tank; the MBR-MD coupling membrane is connected to the switch anaerobic / anoxic tank through a water production vacuum pump; the switch anaerobic / anoxic tank is provided with suspended fillers; the MBR-MD coupling membrane comprises: a coupling membrane module, a gas collecting pipe arranged at the lower part of the coupling membrane module, a device A water collecting pipe is placed on the upper part of the coupled membrane module; the coupled membrane module includes an MBR membrane (the inner diameter of the MBR membrane thread used is 1.0 mm, and the outer diameter ranges from 1.2 mm) and a deoxygenation membrane arranged inside the MBR membrane (the inner diameter of the deoxygenation membrane thread used is 0.2 mm, and the outer diameter ranges from 0.25 mm); a membrane purge aeration device (using a perforated aeration tube with a pore size of 8 mm) is arranged at the lower part of the coupled membrane module, a blower for blowing air to the coupled membrane module, and a water production vacuum pump connected to the gas collecting pipe, and the gas collecting pipe is connected to the microporous aeration disk at the bottom of the aerobic tank through the degassing vacuum pump.

[0124] After being filtered by ultra-fine grids, the sewage flows into the aerobic zone and the anaerobic / anoxic zone in a ratio of 4:1, with a total residence time of 8 hours: in the aerobic zone, the membrane module is perforated for aeration and oxygen is supplied, and the sewage flowing into the aerobic zone undergoes nitrification reaction under the action of aerobic nitrifying bacteria to convert ammonia nitrogen into nitrate nitrogen and nitrite nitrogen. After being filtered by the MBR membrane, the sewage enters the inner layer of the MBR membrane. The filtered sewage contacts the MD deoxygenation membrane in the inner layer of the MBR membrane. The oxygen in the sewage is extracted / purged by the degassing vacuum pump under the action of negative pressure / partial pressure and collected to the bottom gas collecting pipe. The gas collecting pipe is connected to the microporous aeration plate in the aerobic zone. At this time, the recovered oxygen-rich air supplies oxygen to the aerobic zone through the microporous aeration plate, and the deoxygenated sewage is pumped into the anaerobic / anoxic zone by the water production vacuum pump. The sewage enters the anaerobic / anoxic zone twice. The first time is that the untreated sewage enters the anaerobic / anoxic zone directly in an appropriate proportion. The hydraulic retention time of this stage is 4 hours. The sewage provides a carbon source for denitrifying polyphosphate bacteria. Since there is no aeration device in the anaerobic / anoxic zone, the denitrifying polyphosphate bacteria release phosphorus and synthesize PHA / PHB and store it in the body under completely anaerobic conditions. The second time is that the vacuum pump pumps the sewage that has been treated with nitrification and deoxygenation into the anaerobic / anoxic zone. The hydraulic retention time of this stage is 4 hours. The nitrate nitrogen / nitrite nitrogen in the nitrification liquid changes the anaerobic / anoxic zone from an anaerobic environment to an anoxic environment. The denitrifying polyphosphate bacteria use nitrate nitrogen / nitrite nitrogen as an electron acceptor and use the PHA / PHB stored in the body as energy. While absorbing phosphorus, they reduce nitrate nitrogen / nitrite nitrogen to nitrogen gas, completing simultaneous denitrification and phosphorus removal. After a series of treatments, the sewage is discharged from the anaerobic / anoxic zone.

[0125] The test water was taken from the domestic sewage of a municipal sewage treatment plant in Fujian. The main water quality indicators were: COD Cr =378mg / L, NH3-N=59mg / L, TN=66mg / L, TP=5.6mg / L. The above indicators are all measured according to the standard method in "Water and Wastewater Monitoring and Analysis Methods (Fourth Edition)".

[0126] When the device of this embodiment is in use, the sewage is pumped into the aerobic zone and the anaerobic / anoxic zone respectively through the water inlet pump, the water inlet ratio is 3:1, and the total hydraulic retention time of the sewage in the reactor is 10 hours. It is a sequencing batch reactor: the perforated aeration pipe below the membrane group is aerated for the first 6 hours to provide oxygen for the nitrification reaction of aerobic nitrifying bacteria in the aerobic zone, and in these 6 hours, the sewage entering the anaerobic / anoxic zone provides a carbon source for denitrifying polyphosphate bacteria under completely anaerobic conditions to release phosphorus anaerobically and synthesize PHA / PHB. After 4 hours, the vacuum pump of the MBR-MD coupling membrane system is started, and the oxygen in the sewage in the aerobic zone is removed and recycled and then pumped into the microporous aeration disk to supply oxygen to the aerobic zone, and the deoxygenated sewage is pumped into the anaerobic / anoxic zone. This process lasts for 4 hours. After the deoxygenated nitrification liquid enters the anaerobic / anoxic zone, it brings in nitrate and nitrite. The denitrifying polyphosphate bacteria in the anaerobic / anoxic zone use nitrate nitrogen and nitrite nitrogen as electron acceptors and the PHA / PHB stored in the body as a carbon source (electron donor) to carry out simultaneous denitrification and phosphorus removal.

[0127] According to the above implementation steps, after one month of domestication and cultivation, the effluent COD Cr The average concentrations of NH3-N, TN and TP were 27.6mg / L, 1.1mg / L, 11.6mg / L and 0.8mg / L respectively. Since the water is finally produced by the anaerobic / anoxic zone, the denitrification phosphorus removal process is easy to control, so the system has a good removal effect on TN and TP, meeting the A standard requirements of the first level of the "Urban Wastewater Discharge Standard" (GB18918-2002). In addition, since a special aeration and oxygen supply device is omitted, the gas-water ratio of the system is less than 10:1, which saves more than half of the aeration volume compared to the gas-water ratio of 20:1 to 30:1 of the traditional MBR process, and the system omits the reflux device, so the energy consumption per ton of water treatment in the system (0.58kWh / t) is lower than that of the traditional MBR process (0.9 to 1.3kWh / t).

[0128] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An OMA / A denitrification and phosphorus removal device based on MBR-MD coupling membrane, characterized in that: include: Water inlet device; An ultra-fine grid having an inlet connected to an outlet of the water inlet device; The ultra-fine grid outlets are connected to the aerobic tank and the switchable anaerobic / anoxic tank respectively; A microporous aeration plate disposed at the bottom of the aerobic tank; an MBR-MD coupling membrane whose inlet is connected to the outlet of the aerobic tank; The MBR-MD coupled membrane is connected to the switchable anaerobic / anoxic tank via a water production vacuum pump; The switchable anaerobic / anoxic tank is provided with a suspended filler; The MBR-MD coupling membrane comprises: A coupled membrane module, an air collecting pipe arranged at the lower part of the coupled membrane module, and a water collecting pipe arranged at the upper part of the coupled membrane module; The coupled membrane module comprises an MBR membrane and a deoxygenation membrane arranged inside the MBR membrane; a membrane purge aeration device arranged at the lower part of the gas collecting pipe, a blower for blowing air to the coupled membrane module, a water production vacuum pump connected to the water collecting pipe, and the gas collecting pipe is connected to the microporous aeration disk at the bottom of the aerobic tank through the degassing vacuum pump.

2. The device according to claim 1, characterized in that The deoxygenation membrane is an organic membrane or an inorganic membrane; the deoxygenation membrane is a hollow fiber membrane or a flat membrane; the pore size of the deoxygenation membrane is 0.01-0.03 μm; the diameter of the MBR membrane is 1-3 mm, and the pore size is 0.03-0.4 μm; the membrane purge aeration device is a perforated pipe; The deoxidation method adopted by the deoxidation membrane is: gas purge, negative pressure suction or a combination of gas purge and negative pressure suction.

3. The device according to claim 1, characterized in that In the MBR-MD coupling membrane: the membrane purge aeration device aerates the membrane wires through the gas collecting pipe to make the membrane wires shake and flush the membrane wire surfaces; the aperture of the perforated tube is 3-8 mm.

4. The device according to claim 1, characterized in that The suspended filler is a spherical suspended filler, the ultrafine grid has a specific specification of 1 to 5 mm, and the pore size of the microporous aeration disk is 0.22 to 100 μm.

5. The device according to claim 1, characterized in that The inner diameter of the deoxygenation membrane in the MBR-MD coupling membrane ranges from 0.1 to 0.3 mm, and the outer diameter ranges from 0.2 to 0.4 mm; the inner diameter of the MBR membrane ranges from 0.8 to 1.1 mm, and the outer diameter ranges from 0.9 to 1.2 mm.

6. An OMA / A denitrification and dephosphorization method based on MBR-MD coupling membrane using the denitrification and dephosphorization device according to any one of claims 1 to 5, characterized in that: include: After being filtered through ultra-fine screens, the sewage flows into the aerobic tank and the switchable anaerobic / anoxic tank in proportion; Part of the sewage undergoes nitrification reaction under the action of aerobic nitrifying bacteria in the aerobic tank to convert ammonia nitrogen into nitrate nitrogen and nitrite nitrogen, and the digestate flows into the MBR-MD coupling membrane; The nitrified liquid is filtered through the outer MBR membrane and then enters the inner layer. Under the action of the inner deoxygenation membrane, the gas molecules are pumped to the microporous aeration disk of the aerobic tank, and the deoxygenated nitrified liquid is pumped into the anaerobic / anoxic tank. The other part of the sewage enters the anaerobic / anoxic tank to provide carbon source and phosphorus for the denitrifying polyphosphate bacteria. Under anaerobic conditions, the denitrifying polyphosphate bacteria absorb the carbon source, release phosphorus and obtain energy at the same time; when the deoxygenated nitrification liquid enters, the denitrifying polyphosphate bacteria use nitrate nitrogen / nitrite nitrogen as electron acceptors under anoxic conditions, and use the energy obtained under anaerobic conditions to reduce nitrate nitrogen / nitrite nitrogen to nitrogen gas while absorbing phosphorus, thereby achieving simultaneous denitrification and phosphorus removal.

7. The OMA / A denitrification and phosphorus removal method according to claim 6, characterized in that: The switchable anaerobic / anoxic tank specifically controls the switching between the anaerobic and anoxic environments by the inflow time of the deoxygenated nitrification liquid: there is no aeration device in the anaerobic / anoxic zone, and before the deoxygenated nitrification liquid flows in, the anaerobic / anoxic reaction tank has no molecular oxygen and no combined oxygen, and is an anaerobic environment. After the deoxygenated nitrification liquid flows in, with the entry of combined oxygen, the anaerobic / anoxic reaction tank becomes an anoxic environment.

8. The OMA / A denitrification and phosphorus removal method according to claim 6, characterized in that: The gas molecules are then pumped to the microporous aeration disk of the aerobic tank. Specifically, the gas molecules are pumped out / purged by the degassing vacuum pump under negative pressure / partial pressure and collected into the gas collecting pipe, and then pumped to the microporous aeration disk of the aerobic tank; The deoxygenated nitrification liquid is pumped into the anaerobic / anoxic tank. Specifically, the deoxygenated nitrification liquid is pumped into the anaerobic / anoxic tank by a water production vacuum pump.

9. The OMA / A denitrification and phosphorus removal method according to claim 6, characterized in that: The hydraulic retention time of the aerobic tank is 6 to 10 hours; the hydraulic retention time of the other part of the sewage entering the anaerobic / anoxic tank is 2 to 4 hours; the hydraulic retention time of the deoxygenated nitrification liquid after entering the anaerobic / anoxic tank is 3 to 6 hours; After the sewage is treated for nitrogen and phosphorus removal, the supernatant is discharged from the anaerobic / anoxic zone overflow.

10. The OMA / A denitrification and phosphorus removal method according to claim 6, characterized in that: The inside of the deoxygenation membrane forms an extremely low oxygen negative pressure due to the combined action of the blower air intake and the degassing vacuum pump suction. The oxygen molecules in the sewage are pressed into the deoxygenation membrane under the action of the higher oxygen partial pressure, completing the deoxygenation process.

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