membrane bioreactor
Bioreactor (MBR) is a new wastewater treatment system which combines membrane separation technology and biological treatment technology. The membrane module is used to replace the terminal secondary sedimentation tank of the traditional biological treatment technology, so as to maintain the high activated sludge concentration in the bioreactor and increase the organic load of biological treatment, thereby reducing the occupied area of sewage treatment facilities, and reducing the excess sludge by keeping the sludge load low. Membrane separation equipment submerged in aerobic biological pool is mainly used to intercept activated sludge and macromolecular organic matter in the pool. The concentration of activated sludge (MLSS) in membrane bioreactor system can be increased to 8000 ~ 10000 mg/L or even higher. Sludge age (SRT) can be extended to more than 30 days.
Because of its effective interception, membrane bioreactor can intercept microorganisms with long generation cycle and realize deep purification of sewage. At the same time, nitrifying bacteria can fully propagate in the system, and its nitrification effect is obvious, which provides the possibility for deep phosphorus and nitrogen removal.
Yaxiu membrane bioreactor
Ruijiete membrane bioreactor
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Uses: Sewage treatment: China is a water-deficient country, and sewage treatment and reuse are effective measures to develop and utilize water resources. Sewage reuse refers to the use of urban sewage and industrial sewage for greening, washing, supplementing ornamental water bodies and other non-drinking purposes after being treated by membrane bioreactor and other equipment, while using clean water for drinking and other purposes with high water quality requirements. Urban sewage and industrial sewage can be obtained nearby, avoiding long-distance water transmission, and treated nearby to make full use of water resources. At the same time, sewage can be treated nearby, and it can also prevent sewage from leaking during long-distance transportation and polluting underground water sources. Sewage reuse has been widely used in many water-deficient areas in the world, and it is considered as the most practical sewage treatment technology in 2 1 century.
Comparison of inlet and outlet water quality:
Design influent quality of general urban sewage: BOD 5300mg/L; CODcr 500mg/l； ss 300mg/l； T-N45mg/L
Effluent water quality: BOD 510 mg/l; NH4-n 10.0mg/l； Codcr < 30mg/l; The total number of coliforms with turbidity of 5NTU is 3/L;
There are many kinds of membranes, which are classified according to the separation mechanism, including reaction membranes, ion exchange membranes and osmotic membranes. According to the nature of membrane, there are natural membrane (biofilm) and synthetic membrane (organic membrane and inorganic membrane).
; According to the structural types of membranes, there are flat, tubular, spiral and hollow fiber types.
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Process information MBR is an effective combination of membrane separation technology and biological treatment. Its origin is that membrane separation technology is used to replace the secondary sedimentation tank in activated sludge process for solid-liquid separation. This process not only effectively achieves the purpose of mud-water separation, but also has incomparable advantages over the traditional tertiary sewage treatment process:
1. The solid-liquid separation efficiency is high, and the separation effect is much better than that of the traditional sedimentation tank. The effluent quality is good, the suspended solids and turbidity of the effluent are close to zero, and it can be directly reused, realizing the recycling of sewage.
2. Due to the high efficiency of the membrane, microorganisms are completely trapped in the bioreactor, so that the hydraulic retention time (HRT) and sludge age (SRT) of the reactor are completely separated, and the operation control is flexible and stable.
3. MBR combines the aeration tank and secondary sedimentation tank of traditional sewage treatment into one, replacing all the process facilities of tertiary treatment, which can greatly reduce the floor space and save civil engineering investment.
4, it is beneficial to the interception and reproduction of nitrifying bacteria, and the nitrification efficiency of the system is high. Through the change of operation mode, it can also have the functions of deamination and dephosphorization.
5. Because the age of sludge can be very long, the degradation efficiency of refractory organic matter is greatly improved.
6. The reactor runs under the conditions of high volume load, low sludge load and long sludge age, and the output of excess sludge is extremely low. Because the sludge age can be infinitely long, in theory, zero sludge discharge can be realized.
7. The system realizes PLC control, which is convenient for operation and management.
Membrane bioreactor is a new type of water treatment technology, which combines membrane separation unit and biological treatment unit. The membrane module is used to replace the secondary sedimentation tank to maintain the high activated sludge concentration in the bioreactor, reduce the occupation of sewage treatment facilities, and reduce the amount of sludge by keeping the sludge load low. Compared with traditional biochemical water treatment technology, MBR has the following main characteristics: high treatment efficiency and good effluent quality; Compact equipment and small floor space; Easy to realize automatic control and simple to operate and manage. Since 1980s, this technology has been paid more and more attention and become one of the research hotspots. At present, membrane bioreactor has been applied in more than ten countries, such as the United States, Germany, France and Egypt, with the scale ranging from 6m3/d to.
13000m3/d
The research on MBR in China is less than ten years, but it has developed rapidly.
Domestic research on MBR can be roughly divided into several aspects: (1) Explore the combination of different biological treatment processes and membrane separation units, and the biological reaction treatment process has expanded from activated sludge process to contact oxidation process, biofilm process, composite process combining activated sludge and biofilm, and two-phase anaerobic process; (2) Study the factors, mechanisms and mathematical models that affect the treatment effect and membrane fouling, explore appropriate operating conditions and process parameters, reduce membrane fouling as much as possible, and improve the treatment capacity and operational stability of membrane modules; (3) Expand the application scope of MBR. The research object of MBR extends from domestic sewage to high concentration organic wastewater (food wastewater, beer wastewater) and refractory industrial wastewater (petrochemical wastewater, printing and dyeing wastewater, etc.). ), but mainly focuses on the treatment of domestic sewage.
In China, MBR is used to treat both domestic sewage and industrial wastewater.
These results show that MBR can effectively remove COD, NH3-N, SS and turbidity of various high-concentration organic wastewater and refractory wastewater.
The per capita water resource in China is only 2250m3/ person-year, which is less than the world average 1/4. Among more than 600 cities in China, more than 300 cities are short of water, among which more than 100 cities are seriously short of water, and the annual water shortage is nearly 6 billion m3, resulting in an annual economic loss of about 200 billion yuan. The per capita water resources in North China is only 250-480 m3/ person-year, which is lower than the national average 1/5. Almost all the cities in this area are facing the problem of water shortage. Therefore, sewage reuse is one of the important measures to alleviate the water crisis in North China Plain. Membrane bioreactor technology is regarded as a water-saving technology with good economic, social and environmental benefits because of its high-quality effluent quality, which has attracted much attention. Although there is still a high operating cost, with the progress of membrane technology, the improvement of membrane quality and the reduction of membrane production cost, the investment of MBR will also decrease. For example, the development of polyethylene hollow fiber membrane and new ceramic membrane has greatly reduced its cost compared with the past. On the other hand, the development of various new membrane bioreactors has also greatly reduced the actual operating cost, such as gravity submerged MBR and anaerobic MBR operating at low pressure, which greatly reduced the operating cost compared with the traditional aerobic pressurized membrane bioreactor. Therefore, in the long run, the application scope of membrane bioreactor in water treatment will be wider and wider. Today, with the increasingly strict water environment standards, MBR has shown its great development potential and will become a strong competitor to replace the traditional sewage treatment technology in the new century.
Technical advantages: Under the filtration of MLSS and microfiltration membrane, the effluent quality is stable and high-quality. Under high volume load, the residence time is short, and the MBR process is simpler than the traditional system.
Reduce the floor space, completely replace the sedimentation tank and sand filtration unit, and save the floor space by 30% compared with the traditional method. The MLSS concentration in the reaction tank without sludge settling problem can reach above 10000mg/L, which has strong load impact resistance and can effectively treat high-concentration organic wastewater.
Under microfiltration membrane filtration, the separation effect is much better than that of traditional sedimentation tank and sand filtration unit, and the effluent quality is good and stable, with suspended matter and turbidity.
After being treated, the low-level and generally low-pollution municipal sewage can be directly used as water for middle waterways or on-site resource recovery, which is beneficial to the interception, growth and reproduction of nitrifying bacteria with slow proliferation. The nitrification efficiency of the system is improved, and the removal efficiency is high under the A/O reaction.
The role of nitrogen. A/O method and A2O method can effectively remove ammonia nitrogen and phosphorus, especially in water quality control areas. Microfiltration membrane can remove most bacteria and other microorganisms, reduce the dosage of disinfectant and obtain safe reuse water.
Low energy consumption, low operation cost, long SRT and high sludge age during biological interception in the pond, and the sludge volume decreases by more than 1/2 under the condition of biological self-decomposition.
. The low sludge volume is lower than that of the traditional activated sludge method, and the sludge discharge cycle is long and the operation flexibility is high. Biofilm pipeline system belongs to absolute filtration system and high MLSS, which can easily overcome the PLC control design of wastewater system with high biological sludge operation concentration with great variability, easy operation and maintenance, automatic control and convenient management. MLSS = 6000 ~10000 mg/L.
The volume of the biological aerobic sludge tank can be reduced.
It can be used as a closed design, and the membrane separation with low pollution, low noise and low odor greatly improves the treatment efficiency of macromolecular refractory substances in sewage. Standard mobile modular design, quick and simple installation, easy to expand in stages, suitable for the transformation of old sewage treatment plants, only need to add MBR membrane equipment.
The original program is added to the MBR program.
The original process change plan includes two sedimentation tanks, a fast mixing tank, a slow mixing tank, pressurized air flotation, an upflow filter and two activated carbon towers. Almost all can be replaced by MBR.
One of the sedimentation tanks was changed to a flat bottom and put into MBR module. It can replace other original programs.
The treated water quality is better. Discharge water quality from original air flotation to pressurized air flotation;
Cod =182mg/l, SS = 6.5mg/l,
After MBR treatment, NH4-N=0.4mg/l, NO3-N=3 1.4mg/l, and water quality:
Cod =165.5mg/l, SS = 5.7mg/l,
NH4-N = 0. 19 mg/L, NO3-N = 25 mg/L.
The operation and maintenance are easier and the cost is lower. The original program is complicated, with many tanks and machinery, complicated personnel technology and high operation. This requires a lot of manpower.
After changing to MBR pool, backwashing is automatically controlled by PLC. The chemical cleaning procedure is simple, and each group is implemented separately. Personnel operation and management are extremely easy.
There are many cost pools, and the machinery is mostly used by the original sedimentation tank.
Consumables Due to the numerous and complicated machines, there are a large number of consumables. Activated carbon must also be activated or updated. Less machinery, simple form.
5 Application mode 5. 1
It is a new international water treatment technology in 1990s. It combines biological sewage treatment technology and membrane separation technology. Firstly, biochemical technology is used to degrade organic matter in water and domesticate dominant fungi.
Then the suspended matter and water-soluble macromolecular substances are filtered by membrane technology to reduce the turbidity of water and reach the discharge standard. Membrane bioreactor technology can be widely used in sewage treatment and reclaimed water reuse.
5.2 CCAS treatment technology is Continuous Cycle aeration.
System) is a continuous influent SBR aeration system. CCAS is SBR (sequencing batch reactor) wastewater treatment process.
Reactor, sequencing batch process). CCAS sewage treatment process has low requirements for sewage pretreatment, and only mechanical grid and grit chamber are set with the spacing of15 mm.. The core of biological treatment is CCAS reaction tank, and the functions of phosphorus removal, nitrogen removal and degradation of organic matter and suspended matter are all completed, and the effluent can meet the standard.
The unique advantages of CCAS in sewage treatment;
(1) When aerated, the sewage and sludge of CCAS sewage treatment are in a completely ideal mixed state, which ensures the removal rate of BOD and COD, with the removal rate as high as 95%.
(2) The repeated operation modes of "aerobic-anoxic" and "aerobic-anaerobic" strengthen phosphorus absorption and nitrification-denitrification, so that the removal rate of nitrogen and phosphorus reaches over 80% and the effluent index is qualified.
(3) During precipitation, the whole CCAS reaction tank is in a completely ideal precipitation state, and the effluent suspended solids are extremely low, which also ensures the phosphorus removal effect.
The disadvantage of CCAS wastewater treatment process is that each tank runs intermittently at the same time, and manual control is almost impossible. It depends entirely on computer control, which requires high quality of management personnel in the treatment plant and strict requirements on design, training, installation and debugging.
5.3
Continuous microfiltration technology is to use ultrafiltration membrane to selectively filter and separate the liquid, and intercept the liquid mixture within the operating pressure range to achieve the purpose of separation, concentration and purification. At present, continuous ultra-micro filtration technology is widely concerned and used by the market and users, and it is a mature technology. The company's polypropylene hollow fiber membrane module has rich experience in the fields of clean water, river water, deep well water and industrial process concentration treatment. The original water in the membrane system is outside the membrane, and the purified water is inside the membrane, so the reflux ratio is high and the water flow in the membrane tube is large, which is beneficial to reduce membrane pollution. At the same time, by adopting the gas-water mixed backwashing process, the membrane surface can be scrubbed by air, which effectively protects the components, and the membrane cleaning effect is good, which can effectively remove bacteria, microorganisms, suspended solids and other impurities in the water, and the turbidity of the effluent is close to zero. ....
SDI≦2 can be used as pretreatment of RO and NF, which can make RO and NF enter the water, greatly prolong the service life of RO and NF membrane elements and ensure the long-term stable operation of membrane system.
On-line cleaning, combined with the excellent mechanical properties of membrane materials, can use gas-water backwashing technology and cross-flow process, occupying a small area.
Traditional methods need complex process treatment to meet the requirements of RO and NF water inflow. CMF can obtain high-quality pretreated water through one-step filtration, which can be directly used as RO and NF influent, with a water yield of over 95%.
The investment cost is low. Reduce the cost of pretreatment equipment and chemicals.
Prolong the cleaning cycle of ro and NF. The cleaning cycle of RO and NF is extended from 1-3 months to more than half a year, and the service life is extended from 2-3 years to more than 5 years.
Automatic control and remote monitoring can be realized.
Membrane histochemical equipment
The membrane module equipment provided by Taiwan Province Fiber Membrane Company can be directly placed in the biological treatment tank, which is very convenient for the improvement of new and old sewage treatment plants. After accurate calculation and design, the membrane module can effectively reduce membrane pollution and service life, and it has been verified in long-term equipment operation.
Modular design, easy to expand, can be designed as a mobile sewage treatment unit.
According to the owner's demand and production capacity, the processing capacity can be expanded in stages.
Expand the processing capacity in stages and reduce the initial cost investment.
It overcomes the problem that the biological system is not easy to run because of low load.
Membrane module design can be added to the treatment tank at any time according to the design or demand of water.
Simple installation and short construction period
Integrated control and automatic operation
Online cleaning equipment, simple operation.
Select PP and PVDF membrane equipment according to tank volume and demand.
Reclaimed water, that is, reclaimed water after tertiary treatment of urban sewage. Commonly used for irrigation, washing, sanitation, landscaping and other non-drinking functions. Taiwan Province Fiber Membrane is a supplier of MBR hollow fiber membrane system, providing experience in membrane technology application. After years of application experience in MBR membrane bioreactor, the company has developed "TF-MBR-RT" series of automatic control integrated water treatment and reuse equipment. Suitable for small and medium-sized reclaimed water treatment and recycling equipment. It can be used for daily sewage treatment and recycling of scattered users such as living quarters, hotels, tourist resorts, schools, office buildings and ships.
At the annual environmental protection conference held in Italy in 2004, MBR membrane bioreactor was recognized by all parties as the ultimate feasible technology for recycling urban sewage.
Drinking water in remote areas usually comes from groundwater or surface water (such as rivers, rainwater, lakes, etc.). ). Because of the different impurities in raw water, the planning process is also two sets of main structures.