CN101284698A - A method and device for a jet-air-lift split membrane bioreactor - Google Patents

Abstract

The invention provides a jet-flow air-lifting method for separating membrane bioreactors and a device for realizing the method. The ejector is used to replace the traditional blower to realize the air lift of the membrane module, which greatly reduces the energy consumption of operation. Part of the circulating liquid in the biological aeration tank flows through the ejector at high speed, generating negative pressure to inhale air, forming a high-speed mixed gas-liquid two-phase flow, and through a new type of water and gas distribution device, the gas-liquid two-phase flow is evenly sprayed into the In the membrane module, continuous and effective flushing and air scrubbing are carried out, which effectively reduces membrane pollution and prolongs the service life of the membrane. The violent agitation generated by the jet increases the mass transfer rate in the mixed liquid, accelerates the biochemical reaction, and improves the processing efficiency. The invention has low energy consumption in operation, reduces the degree of membrane pollution, and reduces the initial investment cost of equipment. The structure of the device is simple, the floor space is small, the operation is simple, and it is convenient for automatic operation and operation control.

Description

A method and device for a jet-air-lift split membrane bioreactor

technical field

The invention relates to a method for jet-air-lifting separate membrane bioreactors and a device for realizing the method, belonging to the technical fields of sewage treatment and reuse, and membrane bioreactors.

Background technique

With the rapid development of modern industry, the scale of cities continues to expand, water consumption continues to increase, and water resources are becoming increasingly scarce. In order to solve the problem of water shortage, many countries have carried out research on sewage recycling. Membrane bioreactor (Membrane Bioreactor, MBR) has received widespread attention due to its excellent and stable effluent quality. MBR is a new high-efficiency sewage treatment process that organically combines membrane separation and biological treatment technology. It replaces the secondary sedimentation tank in the traditional activated sludge process with membrane modules, and completely separates mud and water through the efficient separation of membrane modules. It has the advantages of high mud concentration, less residual sludge output, and good effluent quality. The research on MBR began in the 1960s, and after decades of development, MBR has become an attractive and competitive option for the treatment and reuse of municipal and industrial wastewater.

According to the position of the membrane module, MBR is divided into two configurations: split type (also known as external type) and submerged type (also known as built-in type, integrated type). Due to its excellent performance, convenient cleaning operation and membrane module replacement, split MBR is favored in the treatment and reuse of wastewater, especially industrial wastewater. In order to control membrane fouling, split MBR needs to generate high-speed cross-flow in the membrane module, and the energy consumption is high, which has become a bottleneck restricting the popularization and application of split MBR.

In recent years, an air-lift split MBR has appeared on the market, known as the third-generation MBR. This system uses blower aeration to form a gas-liquid two-phase cross flow in the membrane module, which reduces the requirements for cross flow velocity and operating energy consumption of membrane fouling control. However, due to the uneven mixing of gas and liquid, the membrane modules of this system are prone to local pollution. Moreover, the aeration of the blower makes the system process complicated, the control is cumbersome, and the operating energy consumption is still high. In actual operation, it is also prone to the danger of the mixed liquid being poured into the blower due to improper operation. In order to solve the above problems, researchers at home and abroad have done a lot of research and made some progress, but these methods have certain shortcomings, and there are still few really effective methods in practical applications. Therefore, developing corresponding technologies for these problems will be of great significance to the popularization and application of MBR.

In the patent of the present invention, the applicant proposed a Jet Airlift SideStream Membrane Bioreactor (JA-SMBR). The high-speed liquid flow generated by the liquid in the jet cuts the air to form a high-speed gas-liquid two-phase turbulent flow, which is evenly sprayed at the bottom of the membrane module through the water and air distribution device, effectively controlling the local pollution of the membrane module. The invention can effectively reduce equipment operation energy consumption, reduce investment cost, control membrane pollution, and make MBR run more stable and efficient.

Contents of the invention

The purpose of the present invention is to provide a method for a jet air lift type split membrane bioreactor, the method adopts the membrane bioreactor process, realizes the air lift effect on the membrane module unit of the split type membrane bioreactor through the jet device, and Compared with the traditional blower air stripping process, the operating energy consumption and equipment investment are greatly reduced; the circulating fluid flows through the ejector at high speed, generates negative pressure to inhale air, forms a fully mixed gas-liquid two-phase flow, and continuously and effectively Air scrubbing can greatly improve the cross-flow rate on the membrane surface and effectively control the occurrence of membrane fouling. The highly turbulent gas-liquid two-phase flow passes through the water and gas distribution device, so that the gas-water mixture is evenly sprayed, which controls the local pollution of the membrane module and prolongs the service life of the membrane. The gas-liquid two-phase vortex greatly increases the dissolved oxygen in the sludge liquid, and significantly improves the biochemical reaction rate. The air inlet of the ejector is equipped with a valve, which controls the intake of air through timing opening and closing, so that a pulsed air lift method can be formed to further reduce membrane pollution.

Another object of the present invention is to provide a jet air-lift type separate membrane bioreactor device, which uses a jet instead of a traditional blower to realize the air lift of the membrane module. The ejector sucks the air through the entrainment of the water jet on the air, and mixes the air into the water through the mass exchange and momentum exchange of the turbulent water flow. The air-liquid mixture has horizontal and vertical energy, which can effectively improve the air-water flow. The flow field distribution and turbulence of the mixed liquid can significantly increase the mass transfer rate, which is conducive to the formation of better turbulence on the membrane surface and greatly delays the formation of membrane fouling. A new type of water and gas distribution device is installed behind the ejector, which improves the uneven distribution of gas and liquid in the traditional blast air lift device, makes the gas-water mixture evenly sprayed, and effectively controls the occurrence of membrane fouling. One direction of the ejector enters, and one direction enters the air. The air inlet of the ejector is equipped with a valve, which controls the intake of air through timing opening and closing, so that a pulsed air lift method can be formed to further reduce membrane pollution.

The present invention is achieved through the following technical solutions:

Disclosed is a jet air lift type separate membrane bioreactor device, comprising a biological circulation aeration tank, a circulation pump, an ejector, a water distribution and air distribution device, an external membrane module, an outlet pump, a backwash pump and a clean water tank. It is characterized in that: the circulating water pump guides the sludge mixed liquid into the ejector connected to it, and a water distribution and gas distribution device is designed behind the ejector, so that the gas-liquid mixed flow is evenly sprayed into the membrane module, and the permeated liquid pipeline of the membrane module is connected with the outlet respectively. The water pump is connected to the backwash pump, the concentrated liquid pipeline is connected to the membrane biocirculation aeration tank, the water outlet pipeline of the water outlet pump, and the water inlet pipeline of the backwash pump are connected to the clear water tank.

The present invention also provides a method for a jet air lift type separate membrane bioreactor, which is characterized in that it includes the following process:

(1) Part of the sludge mixture in the biological circulation aeration tank is pressurized by the circulating pump and then enters the ejector. The flow of the circulating liquid in the ejector generates a huge vortex to entrain air, forming a violently agitated gas-liquid mixed flow, which passes through the water cloth Gas device;

(2) The water distribution and air distribution device makes the gas-liquid mixed flow evenly distributed into the membrane module, continuously and effectively scours and scrubs the membrane module with air, and returns the concentrated liquid formed after flowing through the membrane module to the biological circulation aeration tank for circulation. The permeated side of the membrane module is sucked by the suction pump to flow into the clean water tank for storage.

(3) The air inlet of the ejector is equipped with a valve, which controls the intake of air by opening and closing at regular intervals, so that a pulsed air lift method can be formed to further reduce membrane pollution.

(4) The backwash pump is turned on regularly, and the backwash pump sucks the clean water stored in the clean water tank through the self-priming function to backwash the membrane components.

Compared with the prior art, the present invention has the following advantages and outstanding effects: the ejector is used instead of the traditional blower to realize the air lift effect of the membrane module, which reduces the energy consumption, investment cost and noise pollution of equipment operation; the high turbulence formed in the ejector The fluid gas-liquid two-phase flow increases the degree of gas-liquid agitation, thereby increasing the cross-flow rate on the membrane surface and effectively controlling membrane fouling. Due to the violent agitation formed by the gas-liquid two-phase vortex, the dissolved oxygen in the mixed solution is greatly increased, accelerating Biochemical reaction improves treatment efficiency; the water and gas distribution device improves the uneven distribution of gas and liquid in the traditional blast and air extraction device, makes the gas-water mixture spray evenly, effectively controls the occurrence of local membrane fouling of the membrane module, and prolongs the service life of the membrane . The air inlet of the ejector is equipped with a valve, which controls the intake of air through timing opening and closing, so that a pulsed air lift method can be formed to further reduce membrane pollution. The invention has low energy consumption, light membrane pollution, low equipment investment cost, simple device structure, small occupied area, simple operation and convenient automatic operation control.

Description of drawings

Accompanying drawing is process flow chart of the present invention.

In the figure: 1-Biological cycle aeration tank, 2-Circulation pump, 3-Ejector, 4-Air pipe, 5-Water and air distribution device, 6-Membrane module, 7-Suction pump, 8-Backwash pump , 9-clean water tank, 10-valve.

Detailed ways

The technical process of the present invention will be further described below in conjunction with the accompanying drawings.

As shown in the figure, part of the sludge mixture in the biological circulation aeration tank 1 enters the ejector 3 through the circulation pump 2, and through the entrainment, mixing and cutting of the sludge mixture in the ejector 3, the outside air It is introduced into the ejector 3 through the valve 10 and the air pipe 4, and the mixed liquid of air and sludge forms a turbulent gas-liquid two-phase flow in the ejector 3, and the gas-liquid two-phase flow enters the membrane module 6 through the water and air distribution device 5 In the process, the membrane module 6 is flushed and air-scrubbed, and the concentrated water generated after passing through the membrane module 6 is returned to the biological circulation aeration tank 1, and the water is sucked by the suction pump 7 and sent to the clean water tank 9 for storage. The tank 9 sucks clean water to backwash the membrane module 6 .

Several examples are listed below to illustrate the effects of the present invention, but the scope of the claims of the present invention is not limited thereto.

Example 1: domestic sewage treatment and reclaimed water reuse project, the treatment capacity is 600m ³ /d, the COD _cr of raw water is 200-500mg/L, the BOD is 100-200mg/L, and the SS is 150-200mg/L. After being treated by jet-air-lift split MBR, the effluent COD _cr is less than 50mg/L, the turbidity is less than 1NTU, and the energy consumption is 0.85kW·h/m ³ . The system has been running for one month, and the transmembrane pressure difference (TMP) has risen from 8kPa to 10kPa, and the membrane pressure difference has risen steadily.

Example 2: Tobacco wastewater treatment and reuse project pilot test, the treatment capacity is 2000m ³ /d, raw water COD _cr is 500-2000mg/L, BOD is 150-400mg/L, SS is 200-450mg/L. After being treated by jet-air-lift separate MBR, the COD _cr of the effluent is less than 50mg/L, the turbidity is less than 1NTU, and the energy consumption of the MBR part is 0.75kW·h/m ³ . The system has been running for one month, and the transmembrane pressure (TMP) has risen from 8kPa to 12.6kPa, the membrane pressure difference has risen steadily, and the operation is stable.

Claims (6)

1. A method and device for a jet air lift type separation membrane bioreactor, characterized in that it comprises the following processes: (1) The sludge mixed liquid in the biological aeration tank is pressurized by the circulating pump and then enters the ejector. The flow of the circulating liquid in the ejector generates a huge vortex to entrain air, forming a violently agitated gas-liquid mixed flow, which passes through the water and air distribution device ; (2) The water and air distribution device makes the gas-liquid mixed flow evenly distributed into the membrane module to realize the air lift effect, realizes continuous and effective flushing and air scrubbing of the membrane module, and the concentrated liquid formed after flowing through the membrane module is returned to the biological aeration The air pool is circulated, and the water is sucked by the suction pump through the permeable side of the membrane module and flows into the clean water tank for storage. (3) The air inlet of the ejector is equipped with a valve, which controls the intake of air by opening and closing at regular intervals, so that a pulsed air lift method can be formed to further reduce membrane pollution. (4) The backwash pump is turned on regularly, and the backwash pump sucks the clean water stored in the clean water tank through the self-priming function to backwash the membrane components. 2. The method and device for a jet-air-lift separate membrane bioreactor according to claim 1, characterized in that: said jet is for water intake in one direction and air intake in another direction; 3. The method and device of a jet-air-lift separate membrane bioreactor according to claim 1, characterized in that: the water distribution and gas distribution device is installed at the lower end of the membrane module on the pipeline behind the jet device. at the mouth of water; 4. The method and device for a jet-air-lifting separate membrane bioreactor according to claim 1, characterized in that: the air-lifting effect on the membrane module is achieved through the common use of a jet device and a water-distributing device. achieved; 5. The method and device for a jet air-lift separate membrane bioreactor according to claim 1, characterized in that: the jet device is installed at the rear end of the circulating pump; 6 . The method and device for a jet-air lift separate membrane bioreactor according to claim 1 , wherein a valve is provided on the inlet pipeline of the jet. 6 .

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