CN1800052A - Integral membrane biological reaction device for water treatment - Google Patents

Abstract

The invention relates to an integrated membrane biological reaction water treatment device. It contains a reaction tank composed of anoxic zone and aerobic zone, agitator 3 set in anoxic zone 2, aeration tube 6 placed in aerobic zone 4 and an air pump connected to the intake tube 11 12. The inlet pump 16 on the inlet pipe 17 of the anoxic zone 2, the outlet pump 10 on the outlet pipe 7 of the aerobic zone 4, and the return pump 15 on the sludge return pipe 14 from the aerobic zone 4 to the anoxic zone 2 In the circulating activated sludge water treatment device, a membrane module 5 is set in the aerobic zone 4, and the outlet pipe 7 is connected from the outlet of the membrane module 5 to the inlet of the outlet pump 10. The invention has a long operation period, greatly reduces the degree of membrane pollution, can maintain high membrane flux, and ensures that the water quality of the equipment complies with the "Water Quality Standard for Miscellaneous Domestic Water".

Description

Integrated membrane bioreaction water treatment device

technical field

The invention relates to an integrated membrane biological reaction water treatment equipment which combines a circulating activated sludge system process and a membrane filtration technology, and belongs to the technical field of environmental engineering.

Background technique

Membrane separation technology is considered to be one of the most promising high-tech technologies from the end of the 20th century to the middle of the 21st century. Combining membrane separation technology with traditional biological treatment in sewage treatment constitutes a Membrane Bioreactor (MBR for short). . Membrane bioreactor has been widely used due to its simple operation, low sludge yield, small footprint, effective removal of ammonia nitrogen, very effective treatment of refractory industrial wastewater, and reuse water treatment. In various fields, from water supply treatment to domestic sewage and many industrial wastewater treatment.

In the 1960s, the United States first used MBR for wastewater treatment research. In the late 1970s, large-scale aerobic membrane bioreactors began to be applied in North America, and then in Japan in the early 1980s (the same period in South Africa: anaerobic membrane bioreactors) device), in Europe in the mid-1990s and in China in the late 1990s.

The Cyclic Activated Sludge System (CASS) process is a new process developed on the basis of the SBR process and oxidation ditch technology. The filling-discharging interstitial activated sludge treatment process operated in the air mode completes the biodegradation of organic pollutants and the separation of mud and water in one reactor. The CASS process operates in a certain time sequence in a push-flow manner, and its operation process includes three stages: water filling-aeration, water filling-slurry-water separation, and supernatant decanting. These three stages form a running cycle, and each cycle can run continuously.

In recent years, due to people's higher and higher requirements on the quality of water environment, the effluent of traditional biological treatment process is difficult to meet the increasingly stringent sewage discharge standards, and membrane bioreactors are used in the treatment of domestic sewage and industrial wastewater. It has many advantages that cannot be compared with traditional crafts. But it also exposed some shortcomings. In particular, the fouling of the membrane causes the flux of the membrane to decrease, and even makes the membrane unusable, seriously affecting its wide application in practice. In addition, due to the manufacturing process, raw materials and other reasons, the cost of membrane manufacturing is relatively high, and the life is short. Therefore, the high investment and operating costs of MBR have become one of the main problems encountered in the promotion and application of MBR.

With the widespread application of membrane bioreactors and the advancement of membrane manufacturing technology, the investment cost of MBR will be greatly reduced. From this, it can be predicted that membrane bioreactor operations will have more and more economical and technical competitive advantages. And there will be more and more combinations of different biological treatment processes and membrane separation units in the future. Membrane bioreactors have shown an increasingly strong application trend. Combining CASS process and membrane filtration technology into an integrated device to treat domestic sewage and carry out research on reuse, there have been no related reports in China. The process formed by the combination of membrane and sequencing batch bioreactor is a membrane bioreactor with low energy consumption, and the membrane separation process will not affect the activity of microorganisms, so it has a good application prospect.

Membrane bioreactors are divided into three categories: membrane bioreactors; membrane aeration bioreactors; extraction membrane bioreactors. Most of the membrane bioreactors used in sewage treatment are membrane separation bioreactors. Membrane separation bioreactors can be divided into separate and integrated membrane bioreactors according to the placement of membrane modules. The integrated membrane bioreactor means that the membrane module is placed inside the bioreactor, and the specific device is shown in Figure 1. There is an aeration device under the reactor, the air sent by the air compressor forms floating micro-bubbles, and at the same time of aeration, a shear stress is generated on the surface of the membrane, which is beneficial to the decontamination of the membrane surface. Flow out of the membrane module under negative pressure. Its characteristic is that no circulation pump is used, which can avoid the inactivation of microorganisms by shear force and save the pipeline configuration for circulation, and the operation cost is low. For microbial cells with weak shear resistance or small reaction volume, it is more beneficial to use the integrated type. However, when using an integrated membrane bioreactor, the membrane flux is relatively low, and membrane fouling is prone to occur, resulting in a decrease in membrane flux, and even making the membrane unusable, which seriously affects its wide application in practice. In addition, due to the manufacturing process, raw materials and other reasons, the cost of membrane manufacturing is high and the life is short. Therefore, the high investment and operating costs of MBR have become one of the main problems encountered in the promotion and application of MBR.

Circulating activated sludge process (CASS process) is a new form of sequencing batch activated sludge process. Usually, the CASS reaction tank is divided into three reaction zones: biological selector, anoxic zone and aerobic zone, and the volume ratio is generally 1:5:30. The drainage system is an important part of the design of the CASS treatment process, and it is also the most characteristic part of the design and the key part related to the success or failure of the system operation. However, the decanters in actual engineering are often difficult to meet the design requirements. There are more suspended solids in the effluent, high turbidity, and it is difficult to guarantee the quality of the effluent. The effluent of ordinary CASS equipment is not enough to meet the reuse standard.

Contents of the invention

The purpose of the present invention is to provide an integrated membrane bioreaction water treatment device, which has a long operation period of the equipment, greatly reduces the degree of membrane pollution, can maintain a high membrane flux, and ensures that the water quality of the equipment meets the "Water Quality Standard for Domestic Miscellaneous Water" .

In order to achieve the above-mentioned purpose, the idea of the present invention is: the present invention looks at the good application prospects of membrane bioreactors, and on the basis of studying the performance of various membrane modules, combines the circulating activated sludge system process (CASS process) with membrane filtration technology Combined into an integrated membrane bioreactor and applied to the field of sewage treatment. The integrated membrane bioreaction water treatment device in this patent aims at the shortcomings of ordinary MBR and CASS equipment, and uses a hollow fiber membrane system as the drainage system of the integrated equipment to ensure that the effluent of the equipment can meet the "Water Quality Standard for Domestic Miscellaneous Water" (CJ25 .1-89), and the unique drainage method and aeration method make the operation period of the equipment long, the degree of membrane fouling is greatly reduced, and a high membrane flux can be maintained. The present invention uses membrane biofiltration technology for sewage treatment, and is designed based on the circulating activated sludge method, combining it with membrane modules, adopting an integrated form, that is, placing the membrane modules in the CASS reaction tank to form Integrated membrane bioreaction water treatment device.

According to above-mentioned inventive concept, the present invention adopts following technical scheme:

An integrated membrane biological reaction water treatment device, comprising a reaction tank divided into anoxic zone and aerobic zone, agitator arranged in the anoxic zone, aeration pipe placed in the aerobic zone and its connection into The circulating activated sludge is composed of the air pump on the trachea, the water inlet pump on the water inlet pipe in the anoxic zone, the outlet pump on the outlet pipe in the aerobic zone, and the return pump on the sludge return pipe from the aerobic zone to the anoxic zone The water treatment device is characterized in that a membrane module is set in the aerobic zone, and the water outlet pipe is connected from the water outlet of the membrane module to the inlet of the water outlet pump.

The above-mentioned membrane module is a polyvinylidene fluoride hollow fiber membrane module.

The structure of the above-mentioned polyvinylidene fluoride hollow fiber membrane module is: two parallel tubes are respectively connected to the two ends of the polyvinylidene fluoride hollow fiber membrane bundle, and then the two ends of the two parallel tubes are connected to connect to the Outlet pipe from the aerobic zone.

The above-mentioned aeration pipes are 1 to 2 pipes with evenly distributed small perforations on the pipe walls, the ends of which are closed and the head ends are connected to the air intake pipes, and the aeration pipes are laid flat on the bottom of the aerobic zone of the reaction tank .

The above-mentioned air pump, water inlet pipe, water outlet pump, return pump and the electric motor of the agitator are all connected to an automatic control box, and the opening of them is controlled by the automatic control box, so as to realize water inlet aeration—drainage and water inlet aeration— Inlet aeration... Two-stage cycle operation mode.

Compared with the prior art, the present invention has the following obvious outstanding substantive features and significant advantages: the present invention arranges membrane modules in the aerobic zone of the reaction tank in the circulating activated sludge water treatment device, and plays a role of "secondary sedimentation" in the effluent. The role of the "pool" ensures the quality of the effluent water, and an aeration tube is placed at the bottom of the aerobic zone under the membrane module to greatly reduce the degree of membrane pollution, maintain a relatively high membrane flux, and the equipment has a long operating cycle.

Description of drawings

Fig. 1 is a structural schematic diagram of an embodiment of the present invention.

FIG. 2 is a top view of FIG. 1 .

Fig. 3 is a schematic structural view of the polyvinylidene fluoride hollow fiber membrane module in Fig. 1 .

Detailed ways

A preferred embodiment of the present invention is: referring to Fig. 1, Fig. 2 and Fig. 3, this integrated membrane bioreaction water treatment device comprises a reaction pool 1 divided into anoxic zone 2 and aerobic zone 4, arranged on The agitator 3 in the anoxic zone 2, the aeration pipe 6 placed in the aerobic zone 4 and the air pump 12 connected to the intake pipe 11, the water inlet pump 16 on the water inlet pipe 17 of the anoxic zone 2, and the aerobic zone 4 A circulating activated sludge water treatment device consisting of the outlet pump 10 on the outlet pipe 7 and the return pump 15 on the sludge return pipe 14 from the aerobic zone 4 to the anoxic zone 2, the aerobic zone 4 is set A membrane module 5 , the outlet pipe 7 is connected from the outlet of the membrane module 5 to the inlet of the outlet pump 10 . There is also a vacuum pressure gauge 8 on the above-mentioned outlet pipe 7, and an air flow meter 9 on the above-mentioned inlet pipe 11, and a vent pipe and a vent valve 13 on the lower bottom of the reaction tank 1. The membrane module 5 is a polyvinylidene fluoride hollow fiber membrane module. The structure of the membrane module is: two parallel pipes 18 are respectively connected to the two ends of the polyvinylidene fluoride hollow fiber membrane bundle 19, and then the two ends of the two parallel pipes 18 are connected to the aerobic zone 4 Outlet pipe 7. The aeration pipe 6 is a pipe with small perforations evenly distributed on the walls of two pipes, the ends of which are closed and the head end is connected to the air intake pipe 11, and the aeration pipe is tiled in the aerobic chamber of the reaction tank 1. Bottom of Zone 4. The motors of the above-mentioned air pump 12, water inlet pipe 16, outlet pump 10, return pump 15 and agitator 13 are all connected to an automatic control box. Water aeration—inlet water aeration...two-stage cycle operation mode.

During the operation of this example, the activated sludge is taken from Quyang Sewage Plant for domestication, that is, certain growth and reproduction conditions are provided for the activated sludge. During the sludge domestication, the membrane modules are taken out and soaked in clean water, and the domestication is completed after a certain period of time. , put the hollow fiber ultrafiltration membrane module into the device (placed below the lowest water level), and the device starts to run officially.

Wastewater is injected into the anoxic zone at the front end of the CASS reaction tank through a metering pump without aeration. The amount of water inflow is judged by the hydraulic retention time (HRT). The wastewater is denitrified in this zone, and the amount of organic matter is initially reduced, and then the wastewater flows into the main reaction zone (aerobic zone), in which nitrification and organic matter degradation are carried out, the aeration volume in the aerobic zone is determined by a rotameter, the most important purpose of aeration is to provide oxygen for the growth of microorganisms, and the other is through stirring, Make the activated sludge fully contact with the wastewater, and at the same time slow down the membrane fouling. The biologically treated sewage is discharged through the membrane module, and the membrane module plays the role of the secondary sedimentation tank. The sludge in the main reaction area is returned to the anoxic area through the sludge return pump to ensure the amount of denitrified sludge. The sludge is discharged manually, and the sludge discharge time is calculated according to the sludge age SRT.

After a period of operation, it was determined that the optimal process operating conditions of the device were hydraulic retention time HRT=4h, dissolved oxygen DO kept between 2.0-3.5mg/L, temperature controlled around normal temperature, and pH between 6.5-8.0 During the period, the removal effect of the experimental device on the pollutants of the actual domestic sewage under this process condition is as follows:

(1) The influent COD _Cr varies from 215 to 689 mg/L, and the effluent COD _Cr is always lower than 50 mg/L, basically fluctuating around 30 mg/L. The removal rate has been maintained above 85%.

(2) The concentration of ammonia nitrogen in the influent varies between 13 and 41 mg/L, and the removal rate of ammonia nitrogen is stable after one week of official operation. The ammonia nitrogen in the effluent has been lower than 5mg/L, and the lowest is only 0.3mg/L. The maximum removal rate reaches 97.69%.

(3) When the turbidity of the influent water changes between 86.7 and 278, the turbidity of the effluent water does not change much, basically lower than 1.0, and the turbidity removal rate is stable at more than 99%, which is better than the "Water Quality Standard for Domestic Miscellaneous Water" "(CJ25.1-89).

(4) The pH value of the influent water varied between 7.0 and 7.5, and the pH value of the effluent water remained stable at around 7.2; SS was not detected in the effluent water.

The results showed that the COD _Cr and ammonia nitrogen, turbidity, and pH of the effluent were all better than those in the "Water Quality Standard for Domestic Miscellaneous Water" (CJ25.1-89), and no SS could be detected in the effluent. After disinfection, the effluent can be directly reused for urban miscellaneous water such as toilet flushing, road cleaning, fire protection, landscaping, car washing, and construction. It shows that the new integrated membrane bioreactor - circulating activated sludge system process + polyvinylidene fluoride (PVDF) hollow fiber membrane filtration process has a good treatment effect when used in the actual domestic sewage treatment.

Claims (5)

1. An integrated membrane bioreaction water treatment device, comprising a reaction tank (1) divided into anoxic zone (2) and aerobic zone (4), an agitator arranged in the anoxic zone (2) (3), put the aeration pipe (6) in the aerobic zone (4) and the air pump (12) on the air intake pipe (11) connected thereto, the water inlet pump on the water inlet pipe (17) in the anoxic zone (2) (16), the outlet pump (10) on the outlet pipe (7) of the aerobic zone (4), and the return pump (10) on the sludge return pipe (14) from the aerobic zone (4) to the anoxic zone (2) 15) A circulating activated sludge water treatment device is characterized in that a membrane module (5) is arranged in the aerobic zone (4), and the outlet pipe (7) is connected from the outlet of the membrane module (5) The water port is connected to the inlet of the water outlet pump (10). 2. The integrated membrane bioreaction water treatment device according to claim 1, characterized in that said membrane module (5) is a polyvinylidene fluoride hollow fiber membrane module. 3. The integrated membrane bioreaction water treatment device according to claim 2, characterized in that the structure of the polyvinylidene fluoride hollow fiber membrane module is: two parallel pipes (18) are respectively connected to the polyvinylidene fluoride The two ends of the hollow fiber membrane bundle (19) and the two parallel pipes (18) are connected to the outlet pipe (7) of the aerobic zone (4). 4. The integrated membrane bioreaction water treatment device according to claim 1, characterized in that the aeration pipes (6) are 1 to 2 pipes with small perforations evenly distributed on the pipe wall, the ends of which are closed and the ends are closed. The end is connected to the air inlet pipe (11), and the aeration pipe is flatly laid on the bottom of the aerobic zone (4) of the reaction tank (1). 5. The integrated membrane bioreaction water treatment device according to claim 1, characterized in that said air pump (12), water inlet pipe (16), water outlet pump (10), return pump (15) and agitator The motors in (13) are all connected to an automatic control box, and their openings are controlled by the automatic control box to realize water inlet aeration—drainage and water inlet aeration—water inlet aeration...two-stage cycle operation mode.

Images