CN116605982A - A sewage treatment system with an external MBR membrane module for air lift cycle - Google Patents

Abstract

The invention discloses a sewage treatment system with an external MBR membrane module for an air lift cycle, comprising a sewage pretreatment system, a split membrane bioreactor and a backwash system; the sewage pretreatment system is connected to the split membrane bioreactor, The split membrane bioreactor is connected to the backwashing system; the split membrane bioreactor includes interconnected biochemical pools and membrane pools, the biochemical pools are connected to the sewage pretreatment system, and the membrane pools are connected to the backwashing system; The reflux system communicates with the biochemical pool, and is used to return the mixed liquid in the membrane pool to the aerobic section of the biochemical pool through the air stripping reflux system for denitrification. The membrane bioreactor process of the present invention greatly strengthens the function of the bioreactor through the membrane separation technology, and the interception effect of the membrane bioreactor through the microfiltration membrane can increase the amount of activated sludge to more than 5000mg/L, and the sludge load is increased. Compared with the conventional activated sludge method, the tank solution is smaller, and the sedimentation and filtration tanks of the traditional biological treatment method are omitted.

Description

A sewage treatment system with an external MBR membrane module for air lift cycle

technical field

The invention relates to a sewage treatment system with an external MBR membrane module for an air lift cycle, and belongs to the technical field of sewage treatment.

Background technique

Conventional MBR process membrane separation includes the following parts: circulation system, membrane module device, suction system, aeration cleaning system, backwashing dosing system. There are problems such as large floor space and high operating costs.

Contents of the invention

The purpose of the present invention is to provide a sewage treatment system with an external MBR membrane module for air lift cycle, which can solve the technical problems in the background technology.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A sewage treatment system with an external MBR membrane module for airlift circulation, including a sewage pretreatment system, a split membrane bioreactor and a backwash system; the sewage pretreatment system is connected to the split membrane bioreactor, and the split membrane bioreactor The reactor is connected to the backwashing system; the split membrane bioreactor includes interconnected biochemical pools and membrane pools, the biochemical pools are connected to the sewage pretreatment system, and the membrane pools are connected to the backwashing system; the membrane pools are connected to the biochemical The pool is connected, and is used to return the mixed liquid of the membrane pool to the aerobic section of the biochemical pool through the air stripping reflux system for denitrification reaction. An aeration device is installed at the bottom of the membrane module, and large air bubbles are used to aerate to generate turbulent flow, scour the surface of the hollow fiber membranes, and eliminate the dead corners that are prone to mud accumulation between the membranes to the greatest extent. The module adopts the method of collecting water at both ends, which makes full use of the membrane area. This system uses an air lift device to replace the mixed liquid reflux pump in the circulation system, and the air source of the air lift device comes from the scrubbing air of the membrane device and does not need to increase the gas volume. The liquid level difference, thereby returning the mixed liquid to the biochemical pool.

The combination of external membrane separation system and gas circulation system is a new type of membrane bioreactor wastewater treatment technology. It has the following advantages: 1. The activated sludge and macromolecular organic substances in the biological reaction tank are intercepted by using the membrane separation module, so that the concentration of activated sludge is increased, and the hydraulic retention time (HRTS) and sludge retention time (SRT) can be reduced. They are controlled separately, which is beneficial to reduce the difficulty of system control and improve the quality of effluent water; 2. The air lift device is used to replace the mixed liquid return pump, and the air source comes from the original scrubbing air of the membrane device, thereby reducing the overall energy consumption of the system.

In the aforementioned sewage treatment system with an external MBR membrane module for airlift circulation, the sewage pretreatment system includes a grid and a regulating tank, the grid is located upstream of the regulating tank, and there is a lift pump in the regulating tank, and the water outlet of the lift pump The end is located in the biochemical pool.

In the aforementioned sewage treatment system with an external MBR membrane module for airlift circulation, the system also includes a fan unit, the aerobic zone of the biochemical pool has an aerator, and the fan unit communicates with the aerator in the aerobic zone; There is an aerator in the pool, and the fan unit communicates with the aerator in the membrane pool.

In the aforementioned sewage treatment system with an external MBR membrane module for airlift circulation, there is a sludge discharge pipe at the bottom of the membrane tank. The mud discharge pipe outside the pool is provided with a mud discharge pump.

In the above-mentioned sewage treatment system with an external MBR membrane module with an air lift cycle, the air lift device is used to replace the mixed liquid return pump in the traditional MBR system; the air source of the air lift device comes from the scrubbing air of the membrane device; The stripping tube of the stripping device is wrapped on the outside of the membrane device, and is submerged below the liquid surface together with the membrane device.

In the aforesaid sewage treatment system with an external MBR membrane module for airlift circulation, the backwash system includes a water production tank, the bottom of the water production tank communicates with the outlet end of the membrane device in the membrane tank through a backwash pipe, and the backwash pipe A backwash pump is arranged on the top; the backwash pipe is connected with the dosing pipe, the other end of the dosing pipe is connected with the fungicide storage tank, and a metering pump is arranged on the dosing pipe.

In the aforementioned sewage treatment system with an external MBR membrane module for air lift cycle, the water outlet end of the membrane device in the membrane tank is connected with the water production tank through a self-priming pump; the water outlet end of the membrane device in the membrane tank is located at its upper part, and The water inlet end of the inner membrane device is located at its lower part, and the aerator in the membrane tank is located below the water inlet end of the membrane device; the air lift reflux system is located above the membrane device.

In the aforementioned sewage treatment system with an external MBR membrane module for air lift cycle, this system adopts the following sewage treatment method: the sewage first passes through the grille, intercepts and removes large particles and floating objects, and then enters the regulating tank; For the adjustment of water volume and the uniformity of water quality, the load of subsequent treatment processes is reduced; the adjustment tank is equipped with a pre-aeration system, which prevents the precipitation of fine suspended matter in the adjustment tank through pre-aeration, and can also remove part of COD, reducing subsequent aerobic biological treatment. load.

In the aforementioned sewage treatment system with an external MBR membrane module for airlift circulation, the sewage treatment method also includes the following content: after pretreatment, the effluent enters the anoxic zone of the biological pool through the lift pump of the regulating tank, and the activity The sludge uses easily degradable BOD in the influent water as a carbon source to remove some organic matter and release phosphorus, and then enters the anoxic section; the mixed liquid in the aerobic section is returned to the anoxic section through steam lift for denitrification reaction, reducing nitrogen in the effluent Nutrients, the effluent from the anoxic pool enter the aerobic pool, and the removal of BOD, nitrification and phosphorus absorption are completed in the aerobic pool.

Compared with the prior art, the membrane bioreactor process of the present invention greatly strengthens the function of the bioreactor through the membrane separation technology, and has the following characteristics compared with the traditional process:

(1) Small footprint. Membrane bioreactor can increase the amount of activated sludge to more than 5000mg/L through the interception effect of microfiltration membrane, and the sludge load is increased, which is smaller than the pool solution required by conventional activated sludge method, which saves the cost of traditional biological treatment method. Sedimentation, filtration tanks, etc., thus saving floor space and civil engineering costs.

(2) The effluent water quality is good. The water-through pores of the membrane module are less than 0.1 μm, which can efficiently separate solids and liquids. The separation effect is much better than that of traditional sedimentation tanks, and the suspended solids and turbidity of the effluent are close to zero.

(3) Simple management. The high-efficiency interception effect of the membrane makes the microorganisms completely trapped in the reactor, realizes the complete separation of the hydraulic retention time (HRT) and the sludge age (STR) of the reactor, and the operation control is flexible and stable. Fully automatic control can be realized. The daily operation of the whole system can be operated only by observing the filtration pressure, which saves the detailed analysis of sludge return flow, sludge properties, sludge concentration and water quality components. The equipment part of the treatment system is composed of membrane modules and suction pumps (which can be omitted when the water flows out from the water). The membrane modules are assembled according to the area and can be easily dismantled, replaced or cleaned.

(4) The biochemical effect is good. The reactor operates under high volume load, low sludge load and long sludge age, which greatly improves the degradation efficiency of refractory organic matter. It is beneficial to the interception and reproduction of nitrifying bacteria, and the nitrification efficiency of the system is high. The combination of operation modes can also have the functions of denitrification and phosphorus removal. Due to the extremely high sludge concentration and low sludge load of the biological treatment system, and the synergy of high-grade filtration achieved by membrane separation, the entire system has a strong buffer capacity and can maintain good effluent quality when the system is impacted.

(5) Low operating cost. The air stripping device is used to replace the traditional mixed liquid reflux pump, which reduces investment and reduces operating energy consumption.

(6) Membrane self-cleaning function. The fiber membrane is constantly swaying under the agitation of water flow and aeration, and realizes the automatic cleaning function through the friction with water flow and air bubbles, making it difficult to form dirt on the membrane surface. After running for a period of time, the membrane pores are partially blocked and need to be cleaned with a chemical solution, which can be used to wash a single set of membranes without affecting the normal work of other membranes.

Description of drawings

Fig. 1 is a structural representation of an embodiment of the present invention;

Figure 2 is a schematic diagram of the system of the biochemical pool and the membrane pool under normal operating conditions;

Figure 3 is the system schematic diagram of the biochemical pool and the membrane pool under the state of backwashing and chemical enhanced washing;

Fig. 4 is a schematic diagram of the system of the biochemical pool and the membrane pool in the state of online chemical cleaning.

Reference signs: 1-sewage pretreatment system, 2-grid, 3-regulating tank, 4-biochemical tank, 5-split membrane bioreactor, 6-gas lift reflux system, 7-gas lift reflux device, 8 -Sludge pump, 9-Backwash system, 10-Backwash pump, 11-Production water tank, 12-Fan unit, 13-Metering pump, 14-Bactericide storage tank, 15-Self-priming pump, 16-Membrane tank, 17-membrane device, 18-aerator, 19-lift pump.

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Detailed ways

Embodiment 1 of the present invention: a sewage treatment system with an external MBR membrane module for an air lift cycle, including a sewage pretreatment system 1, a split membrane bioreactor 5 and a backwashing system 9; a sewage pretreatment system 1 and a separate The one-piece membrane bioreactor 5 is connected, and the split-type membrane bioreactor 5 is connected with the backwashing system 9; the split-type membrane bioreactor 5 includes interconnected biochemical pool 4 and membrane pool 16, biochemical pool 4 and sewage pretreatment system 1 Communication, the membrane pool 16 is communicated with the backwash system 9; the membrane pool 16 is communicated with the biochemical pool 4 through the air stripping reflux system 6, and is used to return the mixed solution of the membrane pool 16 to the aerobic system of the biochemical pool 4 through the air stripping reflux system 6 denitrification reaction.

The sewage pretreatment system 1 includes a grid 2 and a regulating tank 3 , the grid 2 is located upstream of the regulating tank 3 , the regulating tank 3 has a lift pump 19 , and the outlet of the lift pump 19 is located at the biochemical tank 4 . Wherein, the gap of the grid 2 is 2 mm, and the material is SS304, which is used to intercept large-sized suspended solids and floating solids in the water, prevent the treatment equipment from clogging the water pump, and reduce the treatment load of the subsequent treatment process. The residence time of the regulating tank in the sewage is 6 hours, the effective volume of the regulating pond 3 is 120 cubic meters, and the effective depth is 3 meters.

This system also comprises fan unit 12, and the aerobic zone of biochemical pool 4 has aerator 18, and fan unit 12 communicates with the aerator 18 of aerobic zone; The aerator 18 in the tank 16 is in communication.

The bottom of the membrane pool 16 has a mud discharge pipe, one end of the mud discharge pipe is located in the membrane pool 16, the other end of the mud discharge pipe is located outside the membrane pool 16, and a mud discharge pump 8 is arranged on the mud discharge pipe outside the membrane pool 16.

The backwash system 9 includes a water production tank 11, the bottom of the water production tank 11 communicates with the outlet end of the membrane device 17 in the membrane tank 16 through a backwash pipe, and a backwash pump 10 is arranged on the backwash pipe; The medicine pipe is connected, and the other end of the medicine feeding pipe is connected with the fungicide storage tank 14, and a metering pump 13 is arranged on the medicine feeding pipe.

The water outlet end of the membrane device 17 in the membrane pool 16 is connected to the water production tank 11 through the self-priming pump 15; the water outlet end of the membrane device 17 in the membrane pool 16 is located at its upper part, and the water inlet end of the membrane device 17 in the membrane tank 16 is located at its lower part. The aerator 18 in the membrane tank 16 is located below the water inlet end of the membrane device 17;

This system adopts the following sewage treatment method: the sewage first passes through the grille 2, intercepts and removes large particles and floating objects, and then enters the regulating pool 3; the regulating pool 3 is used for water volume regulation and water quality equalization, reducing the load of subsequent treatment processes The adjustment tank 3 is equipped with a pre-aeration system, which prevents the fine suspended matter from settling in the adjustment tank 3 through pre-aeration, and can also remove part of COD, reducing the load of subsequent aerobic biological treatment.

After pretreatment, the effluent enters the anoxic zone of the biological pool through the lift pump 19 of the regulating tank 3, and the activated sludge uses the easily degradable BOD in the influent water as a carbon source to remove some organic matter and release phosphorus, and then enters the anoxic section; the aerobic section The mixed liquid is returned to the anoxic section through the steam force lifting method for denitrification reaction, reducing the nitrogen nutrients in the effluent, and the effluent of the anoxic pool enters the aerobic pool, and the removal of BOD, nitrification and phosphorus are completed in the aerobic pool. Absorption.

The effluent from the biochemical pool 4 enters through the gate of the membrane pool 16, and each set of membrane pools 16 is equipped with two membrane devices 17. The membrane modules in the membrane device 17 are arranged in one layer, and the self-contained aeration system is connected with the membrane scrubbing air duct. Connecting to the system corresponds to the inlet of the self-priming pump, and the vacuum suction force generated by the water pump draws the water in the membrane pool into the center of each hollow fiber membrane through the filter membrane wall, and then collects and discharges it into the filtered water main pipe.

When the membrane is working, stop or backwash automatically to prolong the service life of the membrane and ensure a stable water flow. The backwash water is filtered water. Aeration of large air bubbles at the bottom of the membrane device 17 generates turbulent flow, scours the surface of the hollow fiber, reduces the accumulation of pollutants on the membrane surface, and reduces the number of chemical cleanings.

After several days of continuous work, the suction negative pressure gradually increases, and the system needs to carry out chemical dosing backwashing, that is, using chemical agents, generally citric acid, sodium hypochlorite, etc., to inject cleaning agents into the backwashing pipeline through the metering pump 13 during backwashing. Clean the membrane to better remove the pollutants attached to the membrane surface and restore the membrane flux.

When the membrane surface is blocked and the transmembrane pressure difference is 20kPa higher than the initial stable operation, and the transmembrane pressure difference cannot be recovered by backwashing or backwashing with chemical dosing, chemical restoration cleaning is required or every six months to one year Do it once.

The chemical recovery cleaning of the membrane module can realize online cleaning without lifting off the membrane pool. Close the water inlet gate of the membrane tank to be cleaned, discharge the sludge in the tank into the regulating tank, backwash the water for cleaning, and then configure it with a higher concentration of chemical reagents for soaking and gas scrubbing to restore the membrane flux. The chemical cleaning agent can choose alkali cleaning or pickling according to the different pollutants. Generally, sodium hypochlorite, sodium hydroxide, citric acid, etc. are used.

As shown in Figure 2, it is the system schematic diagram of the biochemical pool and the membrane pool under normal operating conditions. In this state, N1/N2/N5/N6 is turned on, and N3/N4/N7 is turned off. The incoming air is raised and returned from N2 to the biochemical pool. During this period, the membrane module cooperates with the suction pump to carry out solid-liquid separation and discharge from N6.

Figure 3 is the system schematic diagram of the biochemical pool and the membrane pool in the state of backwashing and chemical enhanced washing. In this state, N1/N2/N5/N7 is turned on, N3/N4/N6 is turned off, and the water flow direction is sucked into the mixed liquid by N1. The air passed through N5 is lifted and returned to the biochemical pool from N2. During this period, the membrane module cooperates with the backwash pump for backwashing. The backwash solution uses membrane modules to produce water, and the chemical enhanced washing is realized by adding chemicals to the backwash solution with a metering pump. The circulation between the membrane module and the biochemical pool remains open during chemical enhanced washing. Prevent the accumulation of local agents from destroying the living environment of microorganisms.

Figure 4 is the system schematic diagram of the biochemical pool and the membrane pool in the state of online chemical cleaning. In this state, N3/N4/N5 is turned on, and N1/N2/N6/N7 is turned off. The incoming air is raised and returned from N4 to the chemical cleaning tank. The chemicals in the chemical backwashing tank are pre-configured. After the cleaning is completed, turn off N3/N4 and empty the cleaning waste. The cleaning box can also be removed to save space. The cleaning speed of this method is much faster than the traditional offline cleaning mode, and one membrane module can be cleaned alone or multiple membrane modules can be cleaned online at the same time. The traditional MBR process is difficult to achieve online chemical cleaning.

Claims (6)

1. The sewage treatment system with the air stripping circulation external MBR membrane component is characterized by comprising a sewage pretreatment system (1), a split membrane bioreactor (5) and a backwashing system (9); the sewage pretreatment system (1) is communicated with the split type membrane bioreactor (5), and the split type membrane bioreactor (5) is communicated with the backwashing system (9); the split membrane bioreactor (5) comprises a biochemical tank (4) and a membrane tank (16) which are communicated with each other, the biochemical tank (4) is communicated with the sewage pretreatment system (1), and the membrane tank (16) is communicated with the backwashing system (9); the membrane tank (16) is communicated with the biochemical tank (4) through the gas stripping reflux system (6), and is used for refluxing the mixed solution of the membrane tank (16) to the aerobic section of the biochemical tank (4) through the gas stripping reflux system (6) for denitrification reaction;

the sewage pretreatment system (1) comprises a grid (2) and an adjusting tank (3), wherein the grid (2) is positioned at the upstream of the adjusting tank (3), a lifting pump (19) is arranged in the adjusting tank (3), and the water outlet end of the lifting pump (19) is positioned in the biochemical tank (4);

the system adopts the following sewage treatment method: the sewage firstly passes through a grid (2) to intercept and remove large particles and floaters, and then enters an adjusting tank (3); the regulating tank (3) is used for regulating water quantity and homogenizing water quality, so that the load of the subsequent treatment process is reduced; the regulating tank (3) is provided with a pre-aeration system, fine suspended matters in the regulating tank (3) are prevented from precipitating through pre-aeration, partial COD can be removed, and the load of subsequent aerobic biological treatment is reduced;

the pretreated effluent enters an anoxic zone of a biological tank through a lifting pump (19) of an adjusting tank (3), and activated sludge enters an anoxic zone after removing part of organic matters and releasing phosphorus by taking easily degradable BOD in the influent water as a carbon source; the mixed liquid of the aerobic section flows back to the anoxic section for denitrification reaction in a vapor lifting mode, nitrogen nutrients in the effluent are reduced, the effluent of the anoxic tank enters the aerobic tank, and BOD removal, nitrification and phosphorus absorption are completed in the aerobic tank.

2. The sewage treatment system with the gas stripping cycle external MBR membrane assembly according to claim 1, wherein the system further comprises a fan set (12), an aerator (18) is arranged in an aerobic zone of the biochemical tank (4), and the fan set (12) is communicated with the aerator (18) in the aerobic zone; an aerator (18) is arranged in the membrane tank (16), and the fan group (12) is communicated with the aerator (18) in the membrane tank (16).

3. The sewage treatment system with the air stripping circulation external MBR membrane assembly according to claim 1, wherein a sludge discharge pipe is arranged at the bottom of the membrane tank (16), one end of the sludge discharge pipe is positioned in the membrane tank (16), the other end of the sludge discharge pipe is positioned outside the membrane tank (16), and a sludge discharge pump (8) is arranged on the sludge discharge pipe positioned outside the membrane tank (16).

4. The sewage treatment system with the gas stripping cycle external MBR membrane assembly according to claim 1, wherein the backwashing system (9) comprises a water production tank (11), the bottom of the water production tank (11) is communicated with the outlet end of a membrane device (17) in a membrane pond (16) through a backwashing pipe, and a backwashing pump (10) is arranged on the backwashing pipe; the backwashing pipe is communicated with the dosing pipe, the other end of the dosing pipe is communicated with the bactericide storage tank (14), and the dosing pipe is provided with a metering pump (13).

5. The sewage treatment system with the gas stripping cycle external MBR membrane assembly according to claim 1, wherein the water outlet end of the membrane device (17) in the membrane tank (16) is communicated with the water production tank (11) through a self-priming pump (15); the water outlet end of the inner membrane device (17) of the membrane tank (16) is positioned at the upper part of the inner membrane device, the water inlet end of the inner membrane device (17) of the membrane tank (16) is positioned at the lower part of the inner membrane device, and the aerator (18) in the membrane tank (16) is positioned below the water inlet end of the membrane device (17); the stripping reflux device (7) is integrated in the membrane device (17).

6. The wastewater treatment system with the air stripping cycle external MBR membrane module of claim 5, wherein the air stripping device is adopted to replace a mixed liquor reflux pump in the traditional MBR system; the air source of the air stripping device is from scrubbing air of the membrane device (17); the stripping tube of the stripping device is wrapped outside the membrane device (17) and is immersed below the liquid level together with the membrane device.