Ultrafiltration device for treating raw water in combination with synchronous flocculation

Abstract

The invention relates to the technical field of water treatment, in particular to an ultrafiltration device for treating raw water through synchronous flocculation and combination. Comprising an ultrafiltration unit and a synchronous flocculation unit, the ultrafiltration unit comprises an ultrafiltration membrane tank, an ultrafiltration membrane assembly, a micro-vortex fluidized filler and an aeration unit; raw water to be treated is injected into the ultrafiltration membrane tank, and an adsorbent is added to adsorb the raw water to be treated; a PVDF (Polyvinylidene Fluoride) ultrafiltration membrane assembly or a plate-type and tubular ceramic ultrafiltration membrane is arranged in the ultrafiltration membrane pool, the water outlet end of the ultrafiltration membrane assembly is connected with a water producing pump through a pipeline, the water outlet end of the water producing pump is connected with a backwashing water tank and produced water, and a certain amount of produced water is stored for backwashing during operation; during backwashing, ultrafiltration produced water in a backwashing water tank is used and is pumped back to the membrane assembly through a backwashing pump; the aeration unit is connected with the ultrafiltration membrane tank and is used for aeration cleaning during physical backwashing; the synchronous flocculation unit comprises a flocculant metering pump and a mechanical stirrer. According to the device, the service life of the membrane can be prolonged, the filtering effect is improved, and meanwhile, the follow-up maintenance frequency and cost are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to an ultrafiltration device for synchronous flocculation combined with raw water treatment. Background Art

[0002] Compared with conventional civil engineering water plants, integrated water treatment equipment has the characteristics of small footprint, less impact from topography, low investment price, simple operation and management, low operating cost and stable effect. In addition, ultrafiltration technology has been widely used due to its excellent turbidity removal effect and biosafety control effect.

[0003] At present, the integrated coagulation-sedimentation-filtration conventional water treatment process is mostly used in water treatment, such as SDJ, LEJI, and LEGS water purifiers. Some equipment has optimized the process by strengthening coagulation. However, due to the small scale of general integrated equipment and the limited time of water purification process, the removal capacity of turbidity, microbial pollutants, etc. will be subject to certain restrictions. Generally, the water treatment efficiency of short-process integrated equipment is poor. Therefore, there is an urgent need for a device that can improve water purification efficiency and shorten the overall process flow. Summary of the invention

[0004] The purpose of the present invention is to improve the water treatment efficiency of short-process integrated equipment and to provide an ultrafiltration device for treating raw water by synchronous flocculation. The ultrafiltration device adopts a hollow fiber membrane or a ceramic membrane as the core, and an online flocculation is simultaneously arranged in the submerged membrane pool to reduce the pollution of the incoming water to the membrane and improve the water purification efficiency. At the same time, the length of the overall process flow is shortened to achieve the goal of meeting the raw water treatment and water supply requirements.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A simultaneous flocculation combined with ultrafiltration device for treating raw water, characterized in that it comprises an ultrafiltration unit and a simultaneous flocculation unit; the ultrafiltration unit comprises an ultrafiltration membrane pool, an ultrafiltration membrane assembly, a micro-vortex fluidized filler and an aeration unit; raw water to be treated is injected into the ultrafiltration membrane pool, and an adsorbent is added to adsorb the raw water to be treated; a PVDF or ceramic ultrafiltration membrane assembly is arranged in the ultrafiltration membrane pool, the outlet end of the ultrafiltration membrane assembly is connected to a water production pump through a pipeline, the outlet end of the water production pump is connected to a backwash water tank and produced water, and a certain amount of produced water is stored during operation for backwashing; the backwash water tank is connected to the backwash pump, and the ultrafiltration produced water in the backwash water tank is used during backwashing, and is pumped back to the membrane assembly pool body through the backwash pump, and then enters the ultrafiltration membrane pool for cleaning; the aeration unit is connected to the ultrafiltration membrane pool, and aeration cleaning is performed during physical backwashing; the simultaneous flocculation unit comprises a flocculant metering pump and a mechanical agitator; water is passed into the ultrafiltration membrane pool through a raw water pump, and a mechanical agitator is arranged at the bottom of the ultrafiltration membrane pool.

[0007] Furthermore, the flocculant is basic aluminum chloride PAC, the molecular formula of which is [Al2(OH)nCl 6-n ]m, where m≤10, n=3~5; the dosage concentration is 5mg / L or other dosage.

[0008] Furthermore, a micro-vortex fluidized filler with a certain filling density is provided in the pool body, and the filler size is not limited to 2-20 cm. A vortex form combining hollow and flow channels is provided inside. The filler can be suspended or floated and fluidized in the ultrafiltration membrane pool 1 under the action of water flow to promote the flocculation of the turbidity of the pool body, which is beneficial to the precipitation and scrubbing of pollutants attached to the ultrafiltration surface.

[0009] Furthermore, the ultrafiltration membrane assembly is a hollow fiber membrane or a ceramic ultrafiltration membrane, the average pore size of which is 0.05 μm, and the material is PVDF or ceramic.

[0010] Furthermore, the aeration unit includes an aeration pump, which passes gas into the ultrafiltration membrane pool through one or more pipelines, and the total aeration typical intensity is 10L / min / m 2 ; Aeration promotes the movement of suspended vortex fillers, increases the chance of collision with the ultrafiltration membrane, and reduces the formation of mud cake layer on the membrane surface.

[0011] Furthermore, the ultrafiltration membrane assembly is fixed about 5-10 cm below the liquid surface of the ultrafiltration membrane pool, and a filtration mode from outside to inside is adopted.

[0012] Furthermore, a water production pump and a backwashing pump are provided for the operation of the ultrafiltration system, and are used for the water production process and the backwashing process respectively.

[0013] Furthermore, the water treatment device performs air-water coordinated backwashing once every period of operation, and the backwashing flux is 40 to 60 LMH.

[0014] Furthermore, after each cycle is completed, a concentration discharge step is performed to discharge 1 / 3 to 1 / 5 of the raw water in the ultrafiltration membrane pool; after several cycles of operation, the ultrafiltration membrane pool is completely emptied to control the concentration of pollutants in the raw water in the ultrafiltration membrane pool.

[0015] Furthermore, the device is connected to a data recording and automatic control unit and is controlled by a PLC system; the data recording and automatic control unit includes a liquid level control system for detecting the liquid level height in the ultrafiltration membrane pool, the liquid level control system is connected to the raw water pump, and a pressure sensor is provided on the pipeline at the water outlet of the membrane assembly, and the pressure sensor is connected to the computer through a communication controller. At the same time, the system automatically controls the switch and start and stop status of each valve and water pump in the device according to feedback.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] This scheme sets a micro-vortex fluidized filler with a certain filling density in the ultrafiltration membrane pool, and its internal structure design allows the filler to be suspended or floated and fluidized in the ultrafiltration membrane pool under the action of water flow. This design can promote flocculation and scrub the ultrafiltration surface adhesion, effectively reducing the deposition of pollutants on the membrane surface. The aeration unit passes gas into the ultrafiltration membrane pool through an aeration pump, which increases the dissolution of gas in the water body, thereby promoting the movement of the suspended vortex filler, increasing the chance of collision with the ultrafiltration membrane, and reducing the formation of mud cake layer on the membrane surface. This physical backwashing also helps to maintain the permeability of the ultrafiltration membrane. The gas-water synergistic backwashing can effectively clean the surface of the ultrafiltration membrane, reduce the accumulation of membrane pollutants, and improve the water purification efficiency. The concentration discharge step helps to control the pollutant concentration in the ultrafiltration membrane pool and reduce the accumulation of pollutants. The automatic control system connects the data recording and automatic control unit and is controlled by the PLC system, in which the liquid level control system, pressure sensor and other devices can monitor and regulate the operating status of the ultrafiltration membrane pool in real time. This automatic control system can accurately control the operation of the device to ensure the accuracy and effectiveness of each step of the operation.

[0018] The water treatment device of the present invention adopts synchronous flocculation treatment to reduce the pollution of the membrane by the influent and improve the water purification efficiency; compared with the conventional water purification process of coagulation-sedimentation-filtration, synchronous flocculation-ultrafiltration can shorten the length of the overall process flow while ensuring the removal effect of turbidity and microbial pollutants; the water treatment device has a relatively simple structure, is not easy to cause membrane pollution, occupies a small area, and is less affected by topography; for the situation where the turbidity and organic pollution of the raw water are both low, synchronous flocculation-ultrafiltration can effectively control the effluent water quality, and has excellent response characteristics to extreme water quality. It has a small investment scale, is easy to produce and install, has low operation and maintenance costs, is automatically controlled, and is easy to transform and upgrade. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a structural diagram of a specific embodiment of the present invention;

[0020] Figure 2 is a diagram of effluent turbidity in certain embodiments of the present invention;

[0021] Figure 3 UV in different types of water 254 and COD Mn Content diagram;

[0022] Figure 4 This is a graph showing changes in TMP during direct ultrafiltration and simultaneous flocculation ultrafiltration.

[0023] The numbers in the figure are: 1. Membrane tank; 2. Flocculant metering pump; 3. Water production pump; 4. Backwash water tank; 5. Aeration pump; 6. Mechanical agitator; 7. Raw water pump; 8. Liquid level control system; 9. Valve; 10. Data recording and automatic control unit; 11. Pressure sensor; 12. Communication controller. DETAILED DESCRIPTION

[0024] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0025] like Figure 1 , an ultrafiltration device for treating raw water by synchronous flocculation, the device consists of three parts: an ultrafiltration unit, a synchronous flocculation unit and a data recording and automatic control unit. The ultrafiltration unit includes a membrane pool 1, into which raw water to be treated is injected, and flocculant is synchronously pumped in through a flocculant metering pump 2 while the water is inletting. An ultrafiltration membrane assembly is arranged in the membrane pool 1, and the outlet end of the membrane assembly is connected to a water production pump 3 through a pipeline, and the outlet end of the water production pump 3 is connected to a backwash tank 4 and produced water. After the water production cycle is completed, the backwash pump uses the produced water in the backwash tank 4 for physical backwashing, and at the same time, the aeration pump 5 starts to work, and gas is passed into the membrane pool 1 through one or more pipelines, and the total aeration intensity is 10L / min / m 2 , and air-water coordinated backwashing is performed. The synchronous flocculation unit is connected to the membrane pool 1. In addition to the flocculant metering pump 2, it also includes a mechanical agitator 6. The mechanical agitator 6 runs continuously during the water production process to improve the flocculation effect. The raw water is introduced into the membrane pool 1 through the raw water pump 7. During the filtration process, the start and stop and the opening and closing of the corresponding valves are controlled by the feedback of the liquid level control system 8. After each cycle of operation, the pus discharge process is controlled by the emptying pipe and valve 9. The data recording and automatic control unit 10 controls the start and stop and opening and closing of each water pump and the corresponding valve, and is respectively connected to the liquid level control system 8, and the pressure sensor 11 on the inlet and outlet pipes. The pressure sensor 11 is connected to the computer through the communication controller 12.

[0026] The flocculant used was basic aluminum chloride (PAC) with a dosing concentration of 5 mg / L. Aeration was continued during the physical backwashing process with an aeration intensity of 10 L / min.

[0027] The ultrafiltration membrane assembly is fixed 6 cm below the liquid level of the membrane pool 1, and the filtration mode is from outside to inside. The water outlet of the membrane is connected to the water production pump by a pipeline. The water production pump provides filtration power. In addition, a backwash pump is set up separately to take water from the backwash water tank for the backwashing step. The constant flow filtration flux in the experiment is 40LMH. The device performs a 90s air-water coordinated backwash every 150min of operation, and the backwash intensity is 40LMH.

[0028] Figure 2The turbidity diagram of the effluent of the embodiment is shown in FIG. 1 . It can be seen from the figure that the turbidity of the effluent of the device can be stabilized below 0.05, and the turbidity removal rate reaches 98.8%. Figure 3 This is the organic matter index diagram. 254 The removal rates of chlorine and permanganate index reached 14.84% and 21.91% respectively. Figure 4 The diagram of the transmembrane pressure difference change of direct ultrafiltration and synchronous flocculation ultrafiltration. The experimental results show that synchronous flocculation can effectively improve the operating stability of the ultrafiltration device.

[0029] In summary, this scheme injects the raw water to be treated into the membrane pool, and simultaneously adds quantitative flocculants and suspended vortex spherical fillers in the pool for micro-flocculation, thereby improving the membrane pollution control effect. An organic ultrafiltration membrane assembly is provided in the membrane pool, which is used to filter the raw water and is connected to the water outlet system through a pipe to achieve the water purification effect. The filtration process can be completed by suction filtration through a centrifugal pump. The membrane assembly is also connected to a backwash centrifugal pump for physical backwashing. The aeration unit is connected to the air pressure, and aeration is performed through the aeration holes set at the bottom of the membrane assembly to clean the ultrafiltration membrane. In view of the characteristics of low turbidity and stable temperature of some raw water, the device uses PVDF organic ultrafiltration membrane as the core, and sets flocculants for synchronous flocculation and suspended vortex spherical fillers. On the one hand, it can promote the flocculation effect, and on the other hand, it can collide with the surface of the ultrafiltration membrane to reduce the pollution of the influent to the membrane and improve the water purification efficiency, while shortening the overall process length to meet the water purification target.

[0030] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A simultaneous flocculation combined with ultrafiltration device for treating raw water, characterized in that: It comprises an ultrafiltration unit and a synchronous flocculation unit; the ultrafiltration unit comprises an ultrafiltration membrane pool (1), an ultrafiltration membrane assembly, a micro-vortex hollow fluidized filler with a diameter of 2 to 20 cm and an aeration unit; the ultrafiltration membrane pool (1) is provided with an ultrafiltration membrane assembly, the water outlet end of the ultrafiltration membrane assembly is connected to a water production pump (3) through a pipeline, the water outlet end of the water production pump (3) is connected to a backwash water tank (4) and produced water, and a certain amount of produced water is stored during operation for backwashing; the backwash water tank (4) is connected to a backwash pump (5); the aeration unit is connected to the ultrafiltration membrane pool (1), and aeration cleaning is performed during physical backwashing; the synchronous flocculation unit comprises a flocculant metering pump (2) and a mechanical agitator (6); water is introduced into the ultrafiltration membrane pool (1) through a raw water pump (7), and a mechanical agitator (6) is provided at the bottom of the ultrafiltration membrane pool (1).

2. The simultaneous flocculation combined with ultrafiltration device for treating raw water according to claim 1, characterized in that: A micro-vortex hollow fluidized filler with a certain filling density is arranged in the pool body. The filler size is not limited to 2-20 cm. A vortex form combining a hollow and a flow channel is arranged inside. The filler can be suspended or floated and fluidized in the ultrafiltration membrane pool (1) under the action of water flow to promote flocculation and scrub pollutants attached to the ultrafiltration surface, thereby forming surface vibration and shear force.

3. The simultaneous flocculation combined with ultrafiltration device for treating raw water according to claim 1, characterized in that: The ultrafiltration membrane component is a hollow fiber membrane or a ceramic ultrafiltration membrane, and its average pore size is 0.05 μm.

4. The simultaneous flocculation combined with ultrafiltration device for treating raw water according to claim 1, characterized in that: The aeration unit comprises an aeration pump (5) for passing gas into the ultrafiltration membrane pool (1) through one or more pipelines, and the total aeration typical intensity is 10 L / min / m 2 , it can achieve 10s ultra-high intensity instantaneous flash-type aeration for vibration.

5. The simultaneous flocculation combined with ultrafiltration device for treating raw water according to claim 1, characterized in that: The ultrafiltration membrane assembly is fixed 5-10 cm below the liquid surface of the ultrafiltration membrane pool (1).

6. The simultaneous flocculation combined with ultrafiltration device for treating raw water according to claim 1, characterized in that: A water production pump (3) and a backwash pump (5) are respectively provided for the operation process of the ultrafiltration system, and are respectively used for the water production process and the backwash process. The backwash has the functions of high-speed flash flushing and utilizing the fluidization of the suspended filler to produce a surface scrubbing effect.

7. The simultaneous flocculation combined with ultrafiltration device for treating raw water according to claim 1, characterized in that: The device is connected to a data recording and automatic control unit (10) and is controlled by a PLC system; the data recording and automatic control unit (10) includes a liquid level control system (8) for detecting the liquid level height in the ultrafiltration membrane pool (1); the liquid level control system (8) is connected to a raw water pump (7); a pressure sensor (11) is provided on the pipeline at the outlet end of the membrane assembly; the pressure sensor (11) is connected to a computer via a communication controller (12); and the system automatically controls the switch and start / stop status of each valve (9) and water pump in the device according to feedback.

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