How to solve the problem of pollution of MBR membrane in sewage treatment

Influencing factors of contamination of MBR membranes:

1. Characteristics of sludge mixture:

2. Operating conditions: cross-flow and turbulent flow, pressure

3. Membrane module: membrane material, membrane pore size, membrane structure

Solution to the contamination of MBR membranes

1. Change the characteristics of the suspension: MBR membrane pollutants mainly come from the activated sludge mixture, and the pretreatment of the membrane and the change of its filtration characteristics can effectively reduce and slow down the membrane pollution. A small amount of flocculant can be added to the bioreactor to flocculate and coagulate fine particles and reduce their deposition on the membrane surface.

2. Shedding and removal of pollutants on the membrane: set an aeration device to increase the aeration volume, produce a water flow shear effect on the surface of the membrane, cause the vibration of the membrane filament near the MBR membrane module, and accelerate the shedding of the deposited pollutants on the membrane surface; When the membrane pollution reaches a certain level, the membrane module should be cleaned to ensure the normal operation of the system, and the commonly used cleaning methods include hydraulic cleaning, chemical cleaning, and ultrasonic cleaning.

3. Reduce the concentration of activated sludge mixture into the membrane: the specific method can add filler to the bioreactor to make the suspended microorganisms adhere to the filler, which can not only accelerate the decomposition rate of pollutants by microorganisms, but also effectively reduce the concentration of activated sludge mixture into the membrane, or control the working flux of the membrane to be lower than the critical flux, delay the deposition rate of pollutants on the membrane, prolong the life of the MBR membrane, and control membrane pollution.

4. Optimize and improve the membrane module: The optimal design of the MBR membrane module should fully consider the placement of the membrane module, the water quality, and the pipe diameter and length of the hollow fiber membrane. Tests have shown that

When there is no aeration, the transverse placement of the membrane filament is better than the axial direction, and the axial placement effect is better when there is aeration. The test results of membrane diameter show that in the cross-flow system, the thin membrane filament is better than the coarse membrane filament, regardless of whether it is aerated or not. Through the model calculation, it is found that when the length of the membrane filament is and the appropriate inner diameter of the membrane is long, the piston flow can effectively increase the membrane flux.

MBR membrane cleaning method

Maintenance cleaning regularly removes contaminants from the membrane surface to inhibit the thickening of the fouling layer and the rise of the cross-membrane pressure difference to achieve the purpose of stable operation. During maintenance cleaning, stop aeration.

The frequency of maintenance cleaning is usually 1 time for 1 week, using Naclo with an effective chlorine concentration of 300mg L and 500mg L, which is quantitatively injected into the membrane module from the permeable side, the agent injection time is 30 minutes, and the agent is soaked for 30 minutes after the injection is completed. The dose per unit membrane area is 2, and the total amount of medicine prepared should be calculated as the capacity of the transportation pipeline.

**Intensive washing is carried out every 1-3 months or when the suction pressure exceeds the set value (when the pressure difference between the membranes rises), the purpose of which is to remove contaminants from the membrane surface and restore the membrane performance to a state close to the initial state. The aeration was stopped, and the Naocl solution with an effective chlorine concentration of 2000-3,000 mg L was injected quantitatively from the permeate side for 30 min, and after the injection was completed, it was allowed to stand for 90 min. The dosage per unit membrane area is 2, and the total amount of reagent preparation should be calculated as the capacity of the conveying pipeline.

After NaOCL cleaning, if the transmembrane pressure difference is still high, ** pickling (1-2% oxalic acid, 1-2% citric acid, hydrochloric acid) can be carried out to remove inorganic scale. When performing acid cleaning, the NaOCL in the pipeline and pump should be cleaned first to avoid the formation of chlorine (toxic gas).

3. Offline cleaning

When the membrane performance cannot be restored by the first two cleaning methods, offline cleaning should be carried out, and the membrane module should be hoisted out and immersed in a special cleaning tank to remove pollutants and restore the membrane performance to a state close to the initial value. Immersion cleaning generally restores membrane properties significantly. For off-line cleaning, the entire module or individual diaphragms are immersed in an alkaline cleaning agent (Naclo solution with a chlorine concentration of 2000-3,000 mg L, pH 10 11) or an acidic cleaning agent (1-2% oxalic or citric acid, sulfuric acid, or hydrochloric acid).

The soaking time is 6 for 24 h and 2 h for acid. The membrane is a single-channel tubular ceramic membrane, the channel support is a porous ceramic material, the inorganic membrane (Al2O3) is plated on the inner surface of the channel, and the membrane filtration adopts a cross-flow process, that is, the main body of the activated sludge mixture flows through the membrane surface along the axial direction, and the filtered water passes through the membrane surface along the radial direction.

How to clean MBR membrane after use?

Clause. 1. Strengthen pretreatment.

Pretreatment is particularly important for the MBR process. Sewage contains a lot of impurities, fibers and suspended solids, which will block the surface of the membrane, thereby reducing the permeable area of the membrane and causing membrane pollution.

Install a fine screen of less than 1 mm. Install a fine sieve on the flow measurement of the biotank. Install a fine sieve in the membrane tank.

Clause. 2. Physical cleaning.

Clause. 3. Chemical cleaning.

The membrane is soaked and cleaned with chemicals.

**Cleaning: In order to prolong the cleaning cycle of MBR membrane, you can consider adding quantitative Naclo and HC1 to the backwash at an interval of 3-6 days for **chemical backwashing, each backwash for 3-5 minutes, and wait for the agent to backwash into the diaphragm, and then put it for 20-30 minutes before putting in normal water, and continue to aerrate during the cleaning process.

Offline cleaning: When the operating negative pressure is exceeded, the MBR diaphragm needs to be cleaned offline in time. The cleaning method is to remove the MBR diaphragm from the membrane frame, rinse the surface of the diaphragm with clean water, and remove the activated sludge attached to the surface of the diaphragm.

It was then soaked with quantitative Naclo and quantitative NaOH solution respectively to kill the bacteria attached to the membrane surface and remove the organic matter and colloidal substances attached to the membrane surface. Then rinse the surface of the diaphragm with clean water, and backwash the diaphragm for 2-3 minutes after loading the membrane cell, and the MBR diaphragm flux can be restored.

Nalco Water can be considered for membrane synergists, which can effectively inhibit the fouling of the MBR stack, extend the cleaning cycle of the MBR stack, reduce membrane filament damage, and extend the service life of the module. The cleaning cycle of the module can be extended from 1-2 months before the application of the synergist to 5-7 months (the specific situation is determined according to the working conditions). At the same time, the synergist does not have any negative impact on the sewage treatment system, which can reduce the formation of foam in the system to a certain extent.

For details, please refer to "Application of MBR Membrane Synergist in Membrane Bioreactor", which was jointly published by Nalco Water and CNOOC.

There are three main ways to generate environmental pollution of MBR membrane in rural domestic sewage treatment equipment:

1. Anaerobic granular sludge layer: mainly when the water passes through the membrane, a part of the activated sludge and colloidal solution chemicals that are intercepted and flowed out are not driven away before they sink on the surface of the membrane due to the effect of the filtration pressure difference and the effect of flowing water, resulting in membrane environmental pollution.

2. Solubility of organic compounds: The first organic compound is mainly the metabolic substance of microbial strains, which can produce a gel layer on the surface of the membrane, and can also be adsorbed on the surface of the microplate in the membrane and block the pores, so that the membrane diffusion coefficient is reduced.

3. Environmental pollution of microbial strains: There are nutrients required by microorganisms on the membrane surface and in the microplate in the membrane, so it is inevitable that there are many microbial strains growing.

The MBR membrane process can effectively improve HRT and sludge retention time SRT, and is one of the popular processes for integrated domestic sewage treatment equipment.

There are many ways to classify membranes, and the more understandable is to classify them according to the material of the membrane, and the membranes that account for a relatively large proportion of the integrated domestic sewage treatment equipment are polyvinylidene fluoride (PVDF), polyethylene (PE) and polypropylene (PP). From a structural point of view, it is mainly a flat membrane and a hollow membrane. From the perspective of specific materials, there are organic membrane materials and inorganic membrane materials.

Organic membrane materials include: polyolefins, polyethylene, polyacrylonitrile, polysulfone, aromatic polyamides, fluoropolymers, etc. Advantages: the cost is relatively low, the cost is cheap, the manufacturing process of the membrane is relatively mature, the pore size and form of the membrane are also more diverse, and the application is wide.

Inorganic film material: metal, metal oxide, ceramic, hollow glass, zeolite, inorganic polymer materials, etc. Advantages (ceramic membrane as an example):

Acid-resistant, pressure-resistant, temperature-resistant, its flux is high, and the energy consumption is relatively low. Disadvantages: expensive cost, alkali resistance, small elasticity, and certain difficulties in the processing and preparation of membranes.

According to the combination of membrane module and bioreactor, it can be divided into: split, integral, (integrated) composite membrane module, tubular type, plate and frame type, hollow fiber type and other membrane materials, organic membrane, inorganic membrane, pressure-driven form, external pressure type, suction bioreactor, aerobic, anaerobic aeration bioreactor, extraction membrane bioreactor, membrane separation bioreactor.

1. MBR membrane can be divided into ultrafiltration membrane and microfiltration membrane according to pore size, and can be divided into hollow fiber membrane, flat membrane and tubular membrane according to physical form. Hollow fiber membranes are further divided into curtain membranes and column membranes, as well as hollow fiber membranes with lining and hollow fiber membranes without lining. According to the state of use, it can be divided into two types: immersion type and external type, the immersion type is mainly hollow fiber curtain membrane and flat membrane, and the external type mainly refers to the tubular membrane and the column hollow fiber membrane, and the column hollow fiber membrane is not lined.

2. Due to the different properties of membrane modules, MBR can be divided into internal pressure type and external pressure type. The direction of water permeation of the internal pressure type is from the inside of the membrane to the outside, while the external pressure type is just the opposite. However, in practical applications, external pressure MBR is still relatively common, because internal pressure MBR is easy to block, resulting in a decrease in membrane flux, thereby reducing the treatment effect of MBR membrane.

3. According to the combination of membrane module and bioreactor, membrane bioreactor can be divided into three basic types: split type, integrated type and composite type.

Summary. Hello dear <>

The flow rate of the produced water treated by MBR membrane is usually relatively stable, and there will be no large and small situation. MBR membrane treatment technology is an efficient sewage treatment technology, through membrane separation technology and biological reaction technology, the organic matter, microorganisms and other substances in the sewage can be separated and removed, so as to achieve efficient sewage treatment and water resources.

Can the produced water treated with MBR membrane fluctuate from large to small?

Hello dear <>

The flow rate of the MBR membrane is usually relatively stable, and there will be no fluctuations. MBR membrane treatment technology is an efficient sewage treatment technology, through membrane separation technology and biological reaction technology base wax ball, can separate and remove local organic matter, microorganisms and other substances in the sewage, so as to achieve efficient sewage treatment and water resources**.

In the MBR membrane treatment system, the membrane module is a key component, through the filtration of the membrane, the suspended solids, bacteria and other substances in the sewage can be effectively separated, and the resulting permeate flow is usually relatively stable. However, in practical application, the permeate flow rate of the MBR membrane treatment system will still be affected by the influent water quality, membrane module status, operation management and other factors, so it is necessary to carry out reasonable operation and management of the MBR membrane treatment system to ensure its normal operation and stable permeate flow. I wish you a happy life.

I hope mine helps you

The pump started up at the beginning and the flow rate was normal, but it dropped in a minute.

The flow rate of the MBR membrane treatment permeate pump is normal at the beginning, but the flow drop after one minute is caused by the following reasons: Plugging the filter of the MBR membrane treatment system: The filter of the MBR membrane treatment system has a blockage problem, which leads to an increase in the resistance of the water flow through the filter tank, which leads to a decrease in the flow rate of the pump.

Pump failure: Damage to the parts or mechanical devices of the pump, impellers, bearings, etc., will cause the pump flow rate to decline. Pipe chain pin blockage:

The pipes of the MBR membrane treatment system were clogged, resulting in an increase in the resistance of water flow through the pipes, resulting in a decrease in pump flow. Changes in influent water quality: Changes in influent water quality, increased concentration of suspended matter in the water, increased number of microorganisms in the sewage, etc., can also lead to a decrease in pump flow.

The full English name of MBR is Membrane Bio-Reactor, which translates to membrane bioreactor.

Students who have not been in contact with it must think that it is very abstract just by listening to the name, but in fact, it is actually very simple, and everyone can understand it this way.

The biggest change of MBR compared with the traditional activated sludge method is that the secondary sedimentation tank is removed and the membrane tank is added.

To put it simply, the secondary sedimentation tank is to separate the mud and water by gravity, and various emergencies may occur in this link, such as black lumpy sludge residue and foam on the surface of the floating tank on the sludge, which makes countless environmental protection people headaches, and the membrane used in the MBR process has the same function as the traditional secondary sedimentation tank, which is to carry out solid-liquid separation, and the benefit of the membrane is that the separation is more thorough.

Membrane bioreactor (MBR) is a combination of membrane treatment technology and biochemical treatment technology, with the advantages of simple process, good effluent quality, simple operation and management, small land occupation, etc., the technology has been widely used in Germany, the United States, Japan and other countries in the field of sewage treatment and reuse.

Composition of Quante MBR:

From the overall structure, MBR is mainly composed of three parts: membrane module, bioreactor and pump unit, of which the bioreactor is the main place for pollutant degradation, the membrane module is equivalent to the secondary sedimentation tank in the biological treatment system, which plays the role of solid-liquid separation, and the pump is the power of the system effluent.

Process flow: conditioning tank-oxygen tank-MBR

MBR process features:

Compared with other biological treatment processes, the MBR process has the following characteristics:

1) Good effluent quality and high stability: membrane filtration of effluent makes the biological concentration in the bioreactor much higher than that of the ordinary activated sludge method, which greatly improves the biodegradation ability and load impact resistance. At the same time, the sludge has a long residence time, which also allows microorganisms with slow proliferation rate such as refractory organic matter decomposers and nitrifying bacteria to multiply and enrich in the reactor, especially for the removal of refractory organic matter and ammonia nitrogen.

On the other hand, the interception effect of membrane separation on organic macromolecules smaller than the membrane pore size can ensure that the filtered effluent is stable in terms of sterilization, elimination of suspended solids and reduction of BOD.

2) Less land occupation: The membrane bioreactor can maintain a high sludge concentration, usually MLSS is 8 20g L, which is twice that of traditional biological treatment, and the system eliminates the secondary sedimentation tank and sludge reflux equipment, thus saving floor space.

3) Simple operation and maintenance: the membrane separation unit has a simple process, the effluent and operation are not affected by factors such as sludge expansion, the operation and maintenance are simple and convenient, and it is easy to realize automatic control and management.

4) Low sludge disposal water cost: the sludge concentration of the system is high and the sludge age is long, which means that the sludge discharge volume is small, and the sludge production only accounts for 30% of the traditional process, which is extremely beneficial for subsequent sludge treatment.