CN101830607A - Alternate two-stage aerobic membrane bioreactor - Google Patents

Abstract

The invention provides an alternate two-stage aerobic membrane bioreactor. Including the first reactor MBR1, the second reactor MBR2, regulating tank I, flow meter, valve, centrifugal pump, automatic control motor box II, water storage tank IV, lye tank III, acid tank V, first blower GFJ1, Second blower GFJ2, perforated pipe aeration device, shallow aeration device. The invention can realize that after the high-concentration organic wastewater is hydrolyzed and acidified, the effluent directly enters the aerobic membrane bioreactor for treatment without having to undergo the methane-producing phase reaction, and the effluent water quality reaches the standard. Restore membrane flux, fully automatic control, safe, stable and efficient.

Description

Alternate two-stage aerobic membrane bioreactor

technical field

The invention relates to a sewage treatment device.

Background technique

Membrane bioreactors have only been developed for decades, but they are developing rapidly, mainly because membrane bioreactors (MBR) combine biological treatment units and membrane treatment technologies, and the quality of effluent water even reaches the standard for reclaimed water reuse. However, due to serious membrane fouling, limited organic load rate, low level of self-control, and discontinuous effluent, its further popularization and application are affected. The membrane bioreactor disclosed in the Chinese patent application number 02104266.7 is composed of a membrane module, a clean water tank, a water pipeline, a gas pipeline and a water pump. The membrane module is composed of a hollow fiber bundle, an aeration tube, an aeration nozzle, a collection Composed of water pipes, its characteristics are: online monitoring measures are used to effectively detect membrane pollution, pulsating aeration is used during backwashing, which increases the shaking of hollow fiber membranes, reduces membrane surface clogging and pollution, and prolongs membrane life. But there are the following problems: 1. Ordinary membrane bioreactors have limited ability to bear the sludge load, and are not suitable for direct treatment of high-concentration organic wastewater; 2. The self-control effect is poor; 3. The way of backwashing is hydraulic scouring and pulsating aeration. Eliminate deep membrane fouling, and the recovery of membrane flux is not as good as chemical solution flushing. The integrated membrane bioreaction water treatment device disclosed in the patent document with the patent application number 200610023281.8 is an integrated membrane bioreaction water treatment device formed by placing the membrane module in the CASS reaction tank. The circulating activated sludge process (CASS process) divides the reaction tank into three areas: biological selection area, anoxic area, and aerobic area. Microorganisms in different areas degrade organic matter under their respective optimal conditions, so the effluent water quality is good. However, the decanter of the water outlet system is often difficult to meet the design requirements, and the concentration of suspended solids in the outlet water is high, and the turbidity is high. The combination of the MBR water outlet method and the CASS process becomes an integrated membrane biological water treatment device. But there are following problems in this invention: 1, the operation period is long; 2, the water outlet is discontinuous. The alternate two-stage aerobic membrane bioreactor can effectively slow down membrane fouling, continuously discharge water, and realize fully automatic high-load operation.

Contents of the invention

The purpose of the present invention is to provide an alternate two-stage aerobic membrane bioreactor capable of realizing full automatic control, continuous water discharge and treatment of high-concentration organic wastewater.

The purpose of the present invention is achieved like this:

The alternate two-stage aerobic membrane bioreactor of the present invention comprises a first reactor, a second reactor, a regulating tank, a flow meter, a solenoid valve, a suction pump, a water storage tank, an alkali solution tank, an acid solution tank, a first Blower, second blower, perforated pipe aeration device, shallow aeration device; the first electromagnetic valve and the first flow meter are connected to the water outlet of the regulating tank; the regulating tank and the first reactor are connected by the water inlet pipeline, and the second electromagnetic valve The valve and the first COD online measuring instrument are connected between the first flowmeter and the first reactor; the regulating tank and the second reactor are also connected by the water inlet pipeline, and the solenoid valve and the COD online measuring instrument are connected on the water inlet pipeline. The three solenoid valves and the second COD online measuring instrument are connected between the first flowmeter and the second reactor; the third COD online measuring instrument is connected to the water outlet of the first reactor; a branch of the outlet pipeline of the first reactor The pipe is connected to the second reactor, the outlet water of the first reactor is used as the inlet water of the second reactor, and the fourth solenoid valve and the first centrifugal pump are connected to the branch pipeline; the outlet of the second reactor is connected to the fourth COD On-line measuring instrument; a branch pipeline of the outlet pipeline of the second reactor is connected to the first reactor, and the outlet water of the second reactor is used as the inlet water of the first reactor, and the branch pipeline is connected with a fifth electromagnetic valve and the second centrifugal pump; the other branch pipeline of the first reactor outlet pipeline is connected with the water storage tank, and the second flow meter is arranged in front of the water storage tank, and the fourth centrifugal pump, the seventh electromagnetic pump, and the seventh electromagnetic pump are successively connected to the branch pipeline valve; the other branch pipeline of the second reactor is connected to the water storage tank, and the third centrifugal pump and the sixth solenoid valve are connected to the branch pipeline in turn; and the sodium hypochlorite lye tank and the sulfuric acid solution are arranged side by side with the water storage tank tank; the outlets of the water storage tank, the lye tank and the acid tank are respectively connected with the tenth solenoid valve, the fourth flowmeter, the eleventh solenoid valve, the fifth flowmeter, the twelfth solenoid valve and the sixth flowmeter; The outlet pipelines of the water storage tank, alkali solution tank and acid solution tank are connected to the fifth centrifugal pump after they are combined, and after being lifted by the fifth centrifugal pump, they are respectively connected to the first reactor and the second reactor by two backwashing pipelines There is a thirteenth solenoid valve on the backwash pipeline connected to the first reactor, and a fourteenth solenoid valve on the backwash pipeline connected to the second reactor, and the liquid medicine transported in the backwash pipeline directly enters the Reactor: The first reactor and the first reactor are both equipped with membrane purging and aeration systems for dissolved oxygen.

Each reactor is equipped with four membrane modules, and the membranes are polyethylene hollow fiber membranes.

The membrane purging and dissolved oxygen aeration system includes a perforated pipe at the bottom of the reactor and a shallow aeration pipe at the height of one-third of the upper part of the reactor; the first blower is sequentially connected with the fifteenth solenoid valve, the seventh The flowmeter constitutes the first air pipeline, which is connected to the inlet of the shallow aeration pipeline of the first reactor; the first blower is also connected to the sixteenth solenoid valve, and the eighth flowmeter constitutes the first Two air pipelines, the second air pipeline is connected with the inlet pipeline of the aeration device at the bottom of the first reactor; The air pipeline is connected to the inlet of the shallow aeration pipeline of the second reactor; the second blower is also connected to the eighteenth solenoid valve and the tenth flowmeter to form the fourth air pipeline, and the fourth air pipeline is connected to the The inlet pipeline of the bottom aeration device of the second reactor is connected.

The invention provides an aerobic membrane bioreactor with full automatic control, continuous water discharge and treatment of high-concentration organic wastewater. After hydrolysis and acidification, high-concentration organic wastewater can directly enter the membrane bioreactor without going through the methanogenic stage to reduce the concentration of organic matter (after hydrolysis and acidification, lactic acid can be collected, no methane is produced, and greenhouse gases are reduced). With high mud concentration and hollow fiber membrane interception, the effluent water quality can still reach a high standard. At the same time, due to the replacement of microbial phases due to alternate operation, the membrane fouling is slowed down due to the backwashing mode of water washing + air washing, alkali washing, and pickling due to the food chain effect.

The present invention is alternately operated by two membrane bioreactors connected in series, pumps the water out to the water storage tank with a centrifugal pump, and after running for a period of time (through online monitoring of the COD at the water inlet and outlet of the reactor, when the COD removal rate is 40%, the automatic The control system controls the alternation) The primary and secondary membrane bioreactors alternate. Due to the series and alternating operation of the reactors, after the low-load reactors in the early stage are transformed into high-load reactors, the microorganisms in the endogenous respiration can digest and absorb organic matter in excess, so they can withstand higher sludge loads and high-concentration organic wastewater. There is no need for a methanogenic reactor, and the effluent after hydrolysis and acidification can directly enter the reactor. During alternate operation, the organic load in the reactor changes, the aerobic microbial colony changes to a certain extent, and the bacterial flora changes. Due to the action of the food chain, the sludge and loose sludge layer deposited on the membrane surface can be reduced, and the membrane fouling can be slowed down. At the same time, the unique online backwashing method: water washing + air washing, alkali washing, and pickling can more efficiently remove membrane pollution and restore membrane flux to the maximum extent. When backwashing, one reactor is running normally and the other reactor is backwashing online, and the uninterrupted working method ensures the continuity of water outlet. In the present invention, valve 1, valve 4 and valve 5 are manual valves. When the centrifugal pump breaks down, the valves can be manually closed for maintenance; other valves are electromagnetic valves. The backwashing when the pollution is serious is controlled by the automatic control system (II in Figure 1 is the automatic control motor box), which is safe, reliable and stable in operation.

Technical characteristics of the present invention are mainly reflected in:

1. Generally, high-concentration organic wastewater needs to be anaerobically treated before being aerobically treated by a membrane bioreactor until the effluent reaches the standard. In the present invention, the series operation of the two-stage membrane bioreactor can make the high-concentration organic wastewater directly enter the membrane bioreactor after being hydrolyzed and acidified. At 40%, the automatic control system automatically controls the alternation) The two-stage reactors alternate, and the original low-load reactor is used as a new high-load reactor, which avoids the decline in processing capacity caused by a single reactor bearing a higher load when the operation is not alternated. Backwash is a frequent problem and therefore can withstand higher organic loads.

2. During normal operation, the effluent is intermittently sucked by the centrifugal pump, which can slow down membrane fouling. The outlet water is stored in the water storage tank and then continuously pumped out by the centrifugal pump F, so that the continuity of the outlet water can be guaranteed. The flowmeter a and flowmeter b at the water inlet and outlet are connected to the automatic control system. According to the flow detected online, the automatic control system controls the opening and closing of the valve at the water inlet and outlet to ensure that the liquid level in the reactor is maintained within a certain range.

3. When backwashing, the first membrane bioreactor (MBR1) performs backwashing first, and the second membrane bioreactor works normally to ensure that the effluent is relatively constant. The backwash adopts the combined backwashing method of hydraulic flushing (clean water flushing + air flushing) and liquid medicine flushing (1% sodium hypochlorite + 0.035% sulfuric acid) to remove membrane fouling. Clean water washing + air washing can eliminate the sludge deposited between the fiber membranes and the loose sludge layer on the membrane surface; sodium hypochlorite solution can remove microorganisms and organic pollutants on the membrane surface; sulfuric acid solution can remove inorganic scale on the membrane surface and inside. Low-concentration sulfuric acid and sodium hypochlorite lye will not kill microorganisms in the reactor, and the alternate operation of alkali washing and pickling ensures that the pH value in the reactor is relatively constant.

4. During backwashing, the liquid medicine is sucked by the centrifugal pump E, enters from the water inlet, and then pumped out by the centrifugal pump D or C to the regulating tank, and then undergoes biological treatment together with the raw sewage. In this way, the flow path of the liquid medicine enters the interior from the outside of the membrane module and then is sucked to the regulating tank, which is equivalent to soaking the membrane module in the liquid medicine, cleaning the inner and outer surfaces of the membrane at the same time, and the membrane flux recovery is large.

5. The opening and closing of the valve during normal work and backwashing are controlled by the automatic control system according to the online monitoring data. Start backwashing when the outlet flow is 40% of the end of backwashing, and stop backwashing when the flow rate after backwashing returns to 90% of the flow rate at the end of the previous backwashing, and work normally again. This is not only safe and reliable, but also ensures that the whole set of equipment operates at the highest load and highest efficiency point in the best state, improves the overall operating performance and reduces energy consumption.

6. Each reactor is equipped with a two-way aeration system for membrane purge and dissolved oxygen supply, and the air supply form is a shallow aeration device (at the height of one-third of the upper part of the reactor) - microporous aerator and a perforated tube aerator at the bottom. The two sets of aeration systems can provide sufficient dissolved oxygen and mix and stir at the same time. During backwashing, aeration is performed at the same time as clean water flushing, which can wash away the particulate dirt on the membrane surface and help restore the membrane flux. At the same time, the shallow microporous aeration system in the middle and upper part can reduce energy consumption, provide more air volume, enhance turbulence, and speed up the oxygen transfer rate.

7. There are four membrane modules in each reactor, and the membranes are polyethylene hollow fiber membranes. The hollow fiber of the fixed membrane is vertically placed on the bottom surface of the reactor, and the outlet pipe is composed of two ends of the hollow fiber pipe connected with a water collecting pipe parallel to the bottom of the reactor tank. The membrane module consists of two outlet pipes connected to two vertical pipes.

8. The backwash tank includes water storage tank Ⅳ, sodium hypochlorite lye tank Ⅲ and sulfuric acid tank Ⅴ, which are controlled by their respective valves and flow meters. Aerate while flushing with clean water, turn off the aeration system to settle the activated sludge when the drug solution is backwashed online, and use centrifugal pump D or C to pump out the drug solution.

9. A perforated tube aeration device is installed at the lower part of the reactor, and the perforated tube is evenly laid on the bottom of the reactor. A shallow aeration device - a microporous diffuser is installed at one-third of the height of the reactor, and the shallow aeration device is interspersed between the five gaps of the membrane module. The blower GFJ1 and blower GFJ2 provide the required air volume for the first reactor (MBR1) and the second reactor (MBR2) respectively, and the automatic control system controls the opening and closing of valve 15, valve 16, valve 17 and valve 18 respectively , so as to realize the control of the aeration amount of the shallow aeration device in the first and second reactors and the perforated tube aeration device at the bottom.

10. The bottom of the reactor membrane module is provided with a vent pipe and a sludge discharge pipe; the upper part is provided with an overflow pipe to prevent the reactor from being submerged.

11. The data displayed by the flow meter a at the water inlet is Q _IN , and the data displayed by the flow meter b at the water outlet is Q _OUT , when the difference between the two is 90% of the reactor volume (this value is the upper limit) , automatically cut off the water inlet, continuous water outlet; when the difference between the two is 50% of the reactor volume (this value is the lower limit), continuous water inlet, close the water outlet. The above operations are controlled by the automatic control system to ensure the safe and reliable operation of the reactor.

Compared with the existing membrane bioreactor, the structure of the present invention has the advantages of:

1. The two-stage membrane bioreactors in series operate alternately, with a high organic load rate, which can withstand higher organic loads. After hydrolysis and acidification, high-concentration organic wastewater can directly enter this aerobic reactor without the need for methane-producing reactions. The effect is good. It avoids the problems of reduced processing capacity, short operation period and frequent backwashing due to the excessive load of the first-stage membrane bioreactor caused by non-alternate operation.

2. The way of alternate operation and alternate backwashing ensures the continuity of the effluent, and the quality of the effluent is basically not affected.

3. The shallow aeration device using the shallow aeration theory - the double aeration system of the microporous diffuser and the perforated tube aeration device at the bottom can not only provide sufficient dissolved oxygen, increase the degree of turbulence, and accelerate the oxygen release The transmission rate is also reduced because the shallow aeration device reduces energy consumption, increases the air volume, and promotes the scouring and shedding of sludge on the membrane surface.

4. This set of equipment adopts a fully automatic control system, which maintains the constant fluctuation of the water level in the reactor within a certain range, and maintains a certain hydraulic retention time. At the same time, the valve opening and closing of the normal operation, backwashing and aeration systems are all controlled by the automatic control system, so that the entire system operates efficiently and safely.

5. The backwash method of water washing + air washing, alkali washing and pickling can restore the membrane flux to the maximum extent, and the membrane cleaning is thorough.

Description of drawings

Fig. 1 is a principle flow chart of the present invention;

Figure 2-1 is a sectional view of membrane bioreactor 2-2; Figure 2-2 is a sectional view of membrane bioreactor 1-1;

Figure 3-1 is a top view of the membrane module, Figure 3-2 is a sectional view of 1-1 in Figure 3-1, and Figure 3-3 is a sectional view of 2-2 in Figure 3-1;

Figure 4-1 is a schematic structural diagram of the bottom aeration device, Figure 4-2 is a sectional view of 1-1 in Figure 4-1, and Figure 4-3 is a sectional view of 2-2 in Figure 4-1

Figure 5-1 is a schematic structural diagram of a shallow aeration device, Figure 5-2 is a sectional view of 1-1 in Figure 5-1, and Figure 5-3 is a sectional view of 2-2 in Figure 5-1.

Detailed ways

The present invention is described in more detail below in conjunction with accompanying drawing example:

Combined with Figure 1, this set of equipment consists of the following components: membrane bioreactor MBR1, membrane bioreactor MBR2, regulating tank Ⅰ, flow meter, valve, centrifugal pump, water storage tank Ⅳ, lye tank Ⅱ, acid solution tank Ⅴ, automatic Control motor box II, blower GFJ1, blower GFJ2, perforated tube aeration device, and shallow aeration device.

A valve 1, a centrifugal pump G and a flow meter a are connected to the water outlet of the regulating pool. The regulating tank and the first reactor MBR1 are connected by the water inlet pipeline, and the valve 2 and the second COD online measuring instrument are connected on the water inlet pipeline of the regulating pool and the first reactor MBR1, and the valve 2 and the second COD online measuring instrument are connected at the flow rate Between meter a and the first reactor MBR1. The regulating tank and the second reactor MBR2 are also connected by the water inlet pipeline, the valve 3 and the first COD online measuring instrument are connected on the water inlet pipeline, and the valve 3 and the first COD online measuring instrument are connected between the flow meter a and the second reactor MBR2 between. The water outlet of the first reactor MBR1 is connected with the third COD online measuring instrument. A branch pipe of the outlet pipeline of the first reactor MBR1 is connected to the second reactor MBR2, and the outlet water of the first reactor MBR1 is used as the inlet water of the second reactor MBR2, and the valve 4, pressure gauge YLB1 and Centrifugal pump A. Similarly, the fourth COD online measuring instrument is also connected to the water outlet of the second reactor MBR2. A branch pipeline of the outlet pipeline of the second reactor MBR2 is connected to the first reactor MBR1, and the outlet water of the second reactor MBR2 is used as the inlet water of the first reactor MBR1. On this pipeline, a centrifugal pump B, pressure Table YLB2 and valve 5. The other branch of the water outlet pipeline of the first reactor MBR1 is connected to the water storage tank. A flow meter b is installed in front of the water storage tank. The water outlet pipeline is connected with a pressure gauge YLB4 centrifugal pump D, valve 7, valve 7 and flow meter in sequence. b connected. Similarly, another outlet branch pipeline of the second reactor MBR2 is also connected to the water storage tank, and the pipeline is connected with a pressure gauge YLB3, a centrifugal pump C, a valve 6 in sequence, and the valve 6 is connected with a flow meter b. Sodium hypochlorite lye tank and sulfuric acid acid tank are arranged side by side with water storage tank. The outlets of the water storage tank, the lye tank and the acid tank are respectively connected with a valve 10, a flow meter d; a valve 11, a flow meter e; a valve 12, a flow meter f. The outlet pipelines of the water storage tank, alkali solution tank and acid solution tank are connected to the centrifugal pump E after they are merged, lifted by the centrifugal pump E, and then connected to the first reactor and the second reactor respectively by two backwashing pipelines. A valve 13 is provided on the backwash pipeline connected to the first reactor, and a valve 14 is provided on the backwash pipeline connected to the second reactor, and the liquid medicine transported in the backwash pipeline directly enters the reactor. Blower GFJ1 is sequentially connected with valve 15 and flowmeter g, and this air pipeline is connected with the inlet of the shallow aeration pipeline of the first reactor MBR1; blower GFJ1 is also connected with valve 16 and flowmeter h, and this air pipeline The road is connected with the air inlet pipeline of the bottom aeration device of the first reactor MBR1, and the blower GFJ2 is connected with a valve 17 and a flow meter i in turn, and this air pipeline is connected with the inlet of the shallow aeration pipeline of the second reactor MBR2; The blower GFJ2 is also connected with a valve 18 and a flow meter j, and this air pipeline is connected with the inlet pipeline of the bottom aeration device of the second reactor MBR2.

The valves (solenoid valves), centrifugal pumps, flow meters, and COD on-line measuring instruments of the entire reaction device are connected with the motor box of the automatic control system to realize fully automatic control.

Combining Figure 2-1 and Figure 2-2, each reactor is equipped with four membrane modules, the membrane material is polyethylene hollow fiber membrane, the hollow fiber tube is perpendicular to the bottom of the reactor, and the centrifugal pump is parallel to the reactor from the bottom The water collection pipe on the bottom side sucks the water out. A perforated tube aeration device is installed at the bottom of each reactor, and a shallow aeration device is installed between the membrane modules at one-third of the height of the reactor. Blower GFJ1 and blower GFJ2 are used to provide air for the two reactors. The lower part of the reactor is equipped with a vent pipe and a mud discharge pipe, and the upper part is provided with an overflow pipe.

Combined with Figure 1, the two reactors operate in series during normal operation. The first reactor MBR1 transports water to the second reactor MBR2 through the centrifugal pump A, which is realized by controlling the centrifugal pump A through the automatic control system; the second reactor MBR2 transports water to the first reactor MBR1 through the centrifugal pump B, through the control The start and stop of centrifugal pump B is realized. The effluent of the first reactor MBR1 is pumped and transported to the water storage tank by the centrifugal pump D, which is realized by the opening and closing of the control valve 7; The opening and closing realization. A flow meter b is installed between the outlet water of the reactor and the water storage tank to measure the outlet water flow. The water in the water storage tank is continuously sucked out by the centrifugal pump F.

During online backwashing, as shown by the dotted line in the figure, the centrifugal pump E is used to pump water from the water storage tank IV, the alkali tank III and the acid tank V in sequence, and the flow meters d, e and f respectively Control flow, valve 10, valve 11, valve 12 control opening and closing. The alkali solution tank III is a 1% sodium hypochlorite solution with a mass fraction, and the acid solution tank V is a 0.035% sulfuric acid solution with a mass fraction. A valve 13 is provided on the backwash circuit of the first reactor MBR1, and a valve 14 is provided on the backwash circuit of the second reactor MBR2. The medicinal liquid entering the first reactor MBR1 is sucked out of the reactor by the centrifugal pump D and transported to the regulating pool, and a valve 9 is arranged between the first reactor MBR1 and the regulating pool; the medicinal liquid entering the second reactor MBR2 is used The centrifugal pump C sucks out of the reactor and transports it to the regulating tank, with a valve 8 therebetween. A flow meter c is installed between valve 8 and valve 9 and the regulating tank to measure the flux recovery after membrane cleaning.

The working process of the reactor in one cycle:

During normal operation, the first reactor MBR1 is used as the primary membrane bioreactor, and the second reactor MBR2 is used as the secondary membrane bioreactor. Open valve 2 and close valve 3, and the raw sewage enters the first reactor MBR1. In the first reactor MBR1, microorganisms degrade organic substances, and the waste water is initially purified. The effluent from the first reactor MBR1 is sucked out by the centrifugal pump A and transported to the second reactor MBR2, the organic matter is degraded again in the second reactor MBR2, the water body is purified, and then the effluent is pumped by the centrifugal pump C to treat The qualified water is sent to the water storage tank IV, and a certain water level is maintained in the water storage tank IV, and the water is continuously pumped out by the centrifugal pump F. At this time, valve 2, valve 4, and valve 6 are opened, and other valves are all closed. The working state of the centrifugal pump is intermittent suction to reduce membrane pollution. The working cycle of the centrifugal pump is 12 minutes of suction, 2 minutes of stop pumping, and the suction pressure is 0.25MPa (displayed by the pressure gauge in front of the centrifugal pump). After running for a period of time (on-line monitoring of COD at the inlet and outlet of the reactor, when the COD removal rate is 40%, the automatic control system controls the alternation), the first reactor MBR1 and the second reactor MBR2 exchange working status, and the second reaction The device MBR2 is used as the primary membrane bioreactor, and the feed water directly enters the second reactor MBR2. The effluent from the second reactor MBR2 is sucked by the centrifugal pump B to the water inlet of the first reactor MBR1, after being reprocessed by the first reactor MBR1, the effluent is pumped out by the centrifugal pump D to the water storage tank IV. The working state of the centrifugal pump is still pumping for 12 minutes, stopping for 2 minutes, and the suction pressure is 0.25MPa. At this time, valve 3, valve 5, and valve 7 are opened, and the others are all closed. During normal operation, the two sets of aeration devices in each reactor work continuously at the same time. The indication of flow meter a is the inflow flow Q _IN , and the flow of flow meter b is the output flow Q _OUT . When Q _OUT is 40% Q _IN , it indicates that the membrane is seriously polluted and online backwashing starts.

When backwashing, the first reactor MBR1 is backwashed first, and the second reactor MBR2 works normally. The opening and closing conditions of the valves on the water inlet and outlet pipelines are as follows: valve 1, valve 3, and valve 6 are opened, and valve 2, valve 4, valve 5, and valve 7 are closed. The raw water directly enters the second reactor MBR2, and after being biodegraded by the second reactor MBR2, the water is directly pumped out by the centrifugal pump C to the water storage tank. The first reactor MBR1 is backwashed online. The flow rate of backwashing is 40% Q _IN , and the online backwashing is divided into three stages: water washing + air washing, alkali washing and pickling. First perform online water washing + air washing to remove the loose sludge layer on the membrane surface. At this time, valve 10 and valve 13 are opened, valve 11, valve 12 and valve 14 are closed, and the water in the water storage tank IV is sucked to the first reactor MBR1 by the centrifugal pump E, and aeration is performed at the same time, and valve 15, valve 16, Valve 17, valve 18 are all opened. The time of online water washing + air washing is 2 hours, followed by online alkali washing, and the online alkali washing time is 30 minutes. At this time, valve 10 and valve 12 are closed, and valve 11 is opened; in the aeration system, valve 15 and valve 16 are closed, and valve 17 is closed. 1. The valve 18 is opened, the air blower GFJ1 is closed, the air blower GFJ2 is opened, and the opening and closing conditions of other valves remain unchanged. Turn off the aeration system during medicine washing to settle the sludge, and at the same time pump out the medicine solution by the outlet centrifugal pump D, so that the entire membrane is soaked in the medicine solution, and the medicine solution flows from the outer surface of the membrane to the inner surface so that the membrane is thoroughly cleaned , which is beneficial to maximize the recovery of membrane flux. Finally, on-line pickling is carried out. The on-line pickling time is 30 minutes. Valve 10 and valve 11 are closed, and valve 12 is opened. During the entire backwashing process of the first reactor MBR1, the opening and closing conditions of the valves on the backwashing outlet pipeline are as follows: valve 9 is open and valve 8 is closed. After the on-line pickling is completed, the above backwashing process is repeated until the recovery of the membrane flux reaches the predetermined standard. A flow meter c is connected behind the valve 9 to display the recovery of the membrane flux after cleaning. When the flow rate Q _RE of the flow meter c returns to the flow rate Q ₀ after the previous backwashing (the automatic control system updates the record after each backwashing 90% of this value), it indicates that the backwashing is over, and the backwashing to the first reactor MBR1 is stopped. Subsequently, the first reactor MBR1 starts to work normally, and the online backwashing of the second reactor MBR2 starts. The online backwashing process of the second reactor MBR2 is the same as above, and the valve opening and closing conditions during backwashing are: (1) During water washing: valve 1, valve 2, valve 7, valve 8, valve 10, valve 14, valve 15, Valve 16, valve 17, valve 18 open, centrifugal pump C, centrifugal pump D, centrifugal pump E, centrifugal pump F, centrifugal pump G open, blower GFJ1, blower GFJ2 open; valve 3, valve 4, valve 5, valve 6, Valve 9, valve 11, valve 12, and valve 13 are closed, and centrifugal pump A and centrifugal pump B are closed. (2) During alkali cleaning: valve 1, valve 2, valve 7, valve 8, valve 11, valve 14, valve 15, valve 16 open, centrifugal pump C, centrifugal pump D, centrifugal pump E, centrifugal pump F, centrifugal pump G open, blower GFJ1 open; valve 3, valve 4, valve 5, valve 6, valve 9, valve 10, valve 12, valve 13, valve 17, valve 18 close, centrifugal pump A, centrifugal pump B close, blower GFJ2 close . (3) Pickling: valve 1, valve 2, valve 7, valve 8, valve 12, valve 14, valve 15, valve 16 open, centrifugal pump C, centrifugal pump D, centrifugal pump E, centrifugal pump F, centrifugal pump G is on, blower GFJ1 is on; valve 3, valve 4, valve 5, valve 6, valve 9, valve 10, valve 11, valve 13, valve 17, valve 18 are off, centrifugal pump A and centrifugal pump B are off, blower GFJ2 is off .

See the following table for the opening and closing of the electromagnetic valve during the working process and backwashing process:

Blower GFJ2 open open open open open open closed closed open

The liquid level control of this design is realized as follows: When T*(Q _IN -Q _OUT )=90% V (T is the hydraulic retention time, V is the volume of the reactor), stop the water intake, and the centrifugal pump G stops pumping Suction; when T*(Q _IN -Q _OUT )=50% V, keep water inflow, stop water outflow, close valve 6 or valve 7; when the value of Q _IN -Q _OUT is between the two limit values, it is the same as normal situation at runtime.

Among the above valves, valve 1, valve 4, and valve 5 are manual valves, and the rest are electromagnetic valves. The opening and closing states of the valves are all realized by the automatic control system and data management system. Fully automatic control of aeration, water in and out, The backwashing method can ensure the safe, stable and efficient operation of the reactor.

Combining Figure 3-1 to Figure 3-3, the figure shows three views of the membrane module, the reactor is 1.5m long, 1.2m wide and 2.0m wide. There are four membrane modules in the reactor, the membranes are polyethylene hollow fiber membranes, the distance between the membranes is 300mm, and the distance between the membranes and the reactor in the length direction is 300mm; The distance between the membrane modules is 250mm; the height of the membrane module is 1200mm, and the distance from the upper end of the reactor is 500mm. A water collection pipe is installed at the center of the lower part of the membrane module to collect the effluent treated by the membrane bioreactor.

Combined with Figure 4-1 to Figure 4-3, the figure shows the three views of the perforated tube aeration device at the bottom. The blower GFJ1 or blower GFJ2 is connected to the main aeration pipe. The aeration main pipe is 100mm away from the reactor wall; the aeration main pipe is connected to the aeration main pipe, the main pipe is 1200mm long, and the main pipe is 150mm away from the reactor wall; four aeration branch pipes are evenly distributed on the main pipe at intervals of 400mm, and the aeration branch pipe is long 800mm, 200mm away from the reactor wall, branch pipe with an upward and downward inclination angle of 45° symmetrically and uniformly open orifices, the orifice size is 5mm, and the orifice spacing is 75mm.

Combining Figure 5-1 to Figure 5-3, the microporous diffuser of the shallow aeration device is immersed in one-third of the height of the membrane module, 1100mm away from the lower end of the reactor, and the blower GFJ1 or blower GFJ2 is connected to the main aeration pipe, which is 1100mm away from the reactor. 100mm above the 400mm membrane module on the top of the device is the main pipe of the microporous aeration device, which is connected with five branch pipes, and the branch pipes go deep into the membrane module; the distance between the branch pipes is 250mm, 300mm, 300mm, 250mm in turn The distance between the reactor walls is 250 mm. A microporous diffuser is installed on the aeration branch pipe to provide microbubbles with a size of 0.1mm, and the service area is about 0.5m ² /piece. Two microporous diffusers are installed on each branch pipe.

The invention can realize that after the high-concentration organic wastewater is hydrolyzed and acidified, the effluent directly enters the aerobic membrane bioreactor for treatment without having to undergo the methane-producing phase reaction, and the effluent quality reaches the standard. Restore membrane flux, fully automatic control, safe, stable and efficient.

Claims (3)

1. An alternate two-stage aerobic membrane bioreactor, comprising a first reactor, a second reactor, a regulating tank, a flow meter, a solenoid valve, a suction pump, a water storage tank, an alkali solution tank, an acid solution tank, The first blower, the second blower, the perforated pipe aeration device, and the shallow aeration device; the characteristics are: the first solenoid valve and the first flowmeter are connected to the water outlet of the regulating tank; the regulating tank and the first reactor are connected by the water inlet pipe The second solenoid valve and the first COD online measuring instrument are connected between the first flowmeter and the first reactor; the regulating tank and the second reactor are also connected by the water inlet pipeline, and the solenoid valve and the first COD online measuring instrument are connected on the water inlet pipeline. The COD online measuring instrument, the third solenoid valve and the second COD online measuring instrument are connected between the first flow meter and the second reactor; the first reactor outlet is connected to the third COD online measuring instrument; the outlet of the first reactor A branch pipe of the water pipeline is connected to the second reactor, and the outlet water of the first reactor is used as the inlet water of the second reactor, and the fourth solenoid valve and the first centrifugal pump are connected to the branch pipe; the second reactor The water outlet is connected to the fourth COD online measuring instrument; a branch pipe of the outlet pipe of the second reactor is connected to the first reactor, and the outlet water of the second reactor is used as the inlet water of the first reactor, and the branch pipe The fifth solenoid valve and the second centrifugal pump are connected on the road; another branch pipeline of the outlet pipeline of the first reactor is connected with the water storage tank, and a second flow meter is arranged in front of the water storage tank, and a fourth flow meter is connected to the branch pipeline in turn. Centrifugal pump, the seventh solenoid valve; another branch pipeline of the second reactor is connected with the water storage tank, and the branch pipeline is connected with the third centrifugal pump and the sixth solenoid valve in sequence; sodium hypochlorite alkali is arranged side by side with the water storage tank Liquid tank and sulfuric acid tank; water storage tank, lye tank, and acid tank are respectively connected with the tenth solenoid valve, the fourth flowmeter, the eleventh solenoid valve, the fifth flowmeter, and the twelfth solenoid valve , the sixth flowmeter; the water outlet pipelines of the water storage tank, the alkali tank and the acid tank are connected to the fifth centrifugal pump after they are combined, and after being lifted by the fifth centrifugal pump, they are respectively connected to the first by two backwashing pipelines. The reactor and the second reactor, the thirteenth electromagnetic valve is arranged on the backwash pipeline connected to the first reactor, the fourteenth electromagnetic valve is arranged on the backwash pipeline connected to the second reactor, and the backwash pipeline The transported chemical solution directly enters the reactor; both the first reactor and the first reactor are equipped with membrane purging and dissolved oxygen aeration systems. 2. The alternating two-stage aerobic membrane bioreactor according to claim 1, characterized in that: each reactor is equipped with four membrane modules, and the membranes are polyethylene hollow fiber membranes. 3. The alternating two-stage aerobic membrane bioreactor according to claim 1 or 2 is characterized in that: membrane purging and aeration system for dissolved oxygen include a perforated pipe positioned at the bottom of the reactor and a three-way distance from the upper part of the reactor. The shallow aeration pipe at one-half of the height; the first blower is sequentially connected with the fifteenth solenoid valve and the seventh flowmeter to form the first air pipeline, and the first air pipeline and the shallow aeration pipe of the first reactor The pipeline inlet is connected; the first blower is also connected with the sixteenth solenoid valve and the eighth flowmeter to form the second air pipeline, and the second air pipeline is connected with the inlet pipeline of the bottom aeration device of the first reactor ; The second air blower is connected with the seventeenth electromagnetic valve and the ninth flow meter in turn to form the third air pipeline, and the third air pipeline is connected to the inlet of the shallow aeration pipeline of the second reactor; the second air blower simultaneously The eighteenth electromagnetic valve and the tenth flow meter are also connected to form a fourth air pipeline, and the fourth air pipeline is connected with the inlet pipeline of the bottom aeration device of the second reactor.

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