CN105948236A - Integral membrane coagulation reactor (MCR) and water treatment technology - Google Patents

Abstract

The invention provides an integrated membrane coagulation reactor (MCR) and a water treatment process, comprising: a membrane tank, and a membrane module and an aeration device arranged in the same membrane tank. While aerating the bottom of the membrane tank, the coagulant is continuously injected into the membrane tank, and the aeration rate is ≥0.05L/min, so that the coagulant can be dissolved evenly in the membrane tank and the particle size of the flocs can grow steadily. The effective removal of pollutants by the coagulant can slow down the increase of the transmembrane pressure difference caused by the pollutant itself. The interception effect of the ultrafiltration membrane is used to ensure the quality of the effluent. In addition, the floc itself does not damage the membrane surface during operation. Due to the continuous formation of flocs in the membrane tank, the density is relatively high, and the sludge discharge is convenient and the amount of sludge is small. The invention can greatly reduce the occupied area while ensuring the removal efficiency of pollutants and slowing down membrane fouling. The invention can be used for drinking water treatment of polluted water sources, and can also be applied to treatment of urban sewage plants and purification of regenerated water.

Description

Integrated membrane coagulation reactor (MCR) and water treatment process

technical field

The invention belongs to the technical field of water treatment and membrane pollution control, and in particular relates to an integrated membrane coagulation reactor (MCR) and a water treatment process.

Background technique

The conventional water treatment process (coagulation-sedimentation-filtration-disinfection) has been applied for more than 100 years, but with the continuous improvement of water quality pollution and water quality requirements, the conventional process is becoming more and more unsuitable. When people are highly concerned about water quality health risks and are working hard to deal with the technical challenges it brings, new principles, new methods and new processes for water quality security are undergoing positive changes in the actual needs of solving problems. In the process, people regard the application of new materials as the focus of breakthroughs, trying to provide scientific methods and technology for improving traditional water treatment processes in the most basic way. For this reason, the theory and application of membrane purification have become a research hotspot in this field in recent years, and membrane treatment technology has also been widely used in actual water treatment projects.

Although the application of membrane technology in water treatment is becoming more and more common, membrane fouling has always been a bottleneck factor that reduces the efficiency of membrane water purification. In order to effectively slow down and control membrane fouling, a certain degree of coagulation pretreatment is usually carried out before the membrane treatment system. Up to now, two coagulation membrane combination processes have been explored: (1) Conventional membrane combination process, that is, pre-coagulation process. There are coagulation and sedimentation units before the membrane treatment system. The pollutants are first coagulated with the coagulant, and enter the membrane treatment system after passing through the precipitation unit; (2) direct filtration membrane combination process, that is, a short process process. There is no precipitation unit before the membrane treatment system. Pollutants enter the membrane treatment system directly after coagulation.

The conventional membrane combination process contains two treatment units of coagulation and sedimentation, which occupy a large area. On the other hand, the sludge density in the sedimentation tank is relatively small, resulting in a large amount of sludge discharge. At the same time, due to the existence of the sedimentation unit, larger particles tend to sink after coagulation, while smaller particles directly enter the membrane treatment system, resulting in an increased probability of adsorption/blocking of membrane pores and serious membrane fouling.

For the direct filtration membrane combination process, since there is no sedimentation unit, compared with the conventional membrane combination process, the occupied area is smaller. Pollutants enter the membrane treatment system directly after coagulation. The particles are large and difficult to adsorb/block the membrane pores. The degree of membrane pollution is relatively light, but the particles in the membrane tank are easy to settle, resulting in large sludge discharge volume and sludge discharge frequency.

Patent application CN101279805A discloses "Membrane Drinking Water Treatment Process and Equipment", a membrane drinking water treatment equipment, including: a pretreatment unit, a coagulation tank, a membrane separation tank; the pretreatment unit is provided with a coarse grid and a Y Type pipeline filter, etc., to pretreat the raw water to prevent impurities in the raw water from blocking the inlet pump and water meter; the coagulation tank is a mechanical coagulation tank, which coagulates the raw water; the membrane separation tank adopts a curtain membrane module structure , to filter the raw water.

Patent application CN 103566762 A discloses "A Submerged Ultrafiltration System". The coagulant is added to the suction port of the submerged ultrafiltration membrane water inlet pump, and the raw water added with the coagulant enters the submerged ultrafiltration membrane tank for filtration. . The combination process of online coagulation and submerged ultrafiltration membrane is adopted, and the ultrafiltration membrane backwash water is returned to the raw water pipeline for reuse. Moreover, there is a sludge discharge tank at the bottom of the submerged ultrafiltration system, which can discharge sludge regularly to ensure the stable operation of the submerged ultrafiltration system.

On the basis of ensuring the removal efficiency of pollutants, in order to further reduce floor space and sludge discharge, the present invention adopts an integrated membrane coagulation reactor (Membrane Coagulation Reactor, MCR). Aeration through the bottom of the membrane tank makes coagulation uniform and continuous floc formation. Utilize coagulation, especially flocs formed in situ, to efficiently remove pollutants, and at the same time, utilize the interception effect of membrane modules to ensure the quality of effluent water. Compared with the conventional membrane combination process and the direct filtration membrane combination process, the integrated membrane coagulation process not only further reduces the floor area, but also can make full use of the high efficiency of in-situ floc formation after coagulation to better remove pollutants and Reduce fouling of ultrafiltration membranes. In addition, the formed sludge has a higher density, and the sludge discharge is convenient and the sludge volume is smaller.

Contents of the invention

The object of the present invention is to provide a water treatment process and an integrated membrane coagulation reactor (Membrane Coagulation Reactor, MCR) that can effectively reduce the occupied area, facilitate operation and management, and efficiently remove pollutants.

To achieve the above object, the present invention takes the following schemes:

An integrated membrane coagulation reactor (MCR), including: a membrane tank, a membrane module and an aeration device arranged in the same membrane tank; the membrane tank is connected to the coagulant dosing tank through a pipeline series suction pump ; There is also a sludge discharge valve at the bottom of the membrane pool; the reactor is also equipped with an outlet of the membrane pool.

The invention realizes the integration of the coagulation process and the membrane process, and effectively reduces the occupied area while ensuring the removal efficiency of pollutants.

Further, according to the requirements of the membrane treatment process, the membrane module is also connected to a vacuum pressure gauge through a pipeline.

Further, the aeration device is arranged at the bottom of the membrane tank, 10-50 cm away from the upper membrane module.

Further, the aeration device is a perforated aeration tube or an aeration head, and the horizontal spacing of the aeration tube or aeration head is 5-50 cm, and a higher value is taken when the diameter of the aeration tube or aeration head is larger.

Furthermore, the aeration rate of the aeration device is greater than or equal to 0.05 L/min, and a higher value is taken when the degree of membrane fouling is serious.

Further, the membrane module is a low-pressure membrane module, which is submerged and includes a microfiltration membrane or an ultrafiltration membrane, and the end is a free end to facilitate sludge discharge.

The present invention also provides an integrated membrane coagulation water treatment process as follows:

Using the above-mentioned integrated membrane coagulation reactor, a certain concentration of coagulant is configured in the coagulant dosing tank, and under the condition of aeration at the bottom of the membrane tank, the coagulant is continuously pumped into the membrane tank through the suction pump, and waits for The treated water is directly injected into the membrane tank, where coagulation and membrane treatment are performed simultaneously, and the treated water is discharged through the outlet of the membrane tank; in order to ensure the treatment effect, the residence time of the water to be treated in the membrane tank must be ≥ 10min. The physical backwashing time is 20 to 30 minutes, and the backwashing water rate is twice that of the water inflow rate. Maintenance cleaning frequency is 5-10 days/time. When the membrane flux drops to 60-70% of the initial membrane flux, the membrane components must be chemically cleaned.

Further, the coagulant is an inorganic coagulant, and its type is preferably an aluminum salt coagulant, an iron salt coagulant or an aluminum-iron composite coagulant.

Further, the water level in the membrane tank in the treatment process is 100-200 cm higher than the membrane module.

Further, the mud discharge frequency of the process is 5-15 days/time. Every time when mud is discharged, stop the aeration, let it stand for 30 minutes and then discharge the mud, and the water level can drop to the membrane module.

The present invention has the following advantages:

1. Use the aeration at the bottom of the membrane tank to achieve the purpose of coagulation, give full play to the activity of forming flocs in situ, and remove pollutants efficiently.

2. Utilizing the continuous formation of flocs in the membrane tank and the high density of particles in the membrane tank, it is convenient to discharge mud and the amount of mud is small.

3. Small footprint, high water production rate and low water head loss, suitable for renovation of old water plants and construction of new water plants. The operation cost is low, and the operation and management are convenient.

Description of drawings

Figure 1: Schematic diagram of the integrated membrane coagulation reactor of the present invention;

Among them, 1-membrane tank, 2-membrane module, 3-aeration device, 4-suction pump, 5-coagulant dosing tank, 6-vacuum pressure gauge, 7-membrane tank outlet, 8-sludge discharge valve.

detailed description

The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings. Unless otherwise specified, technical means not described in the implementation manners can be implemented by means known to those skilled in the art. In addition, the embodiments should be considered as illustrative rather than limiting the scope of the invention, the spirit and scope of which is defined only by the claims. For those skilled in the art, without departing from the spirit and scope of the present invention, various modifications, replacements and improvements to the material components, dosage, size and shape in these embodiments also belong to the protection scope of the present invention , and the specific parameters defined by the present invention should have a permissible error range.

In order to better understand the present invention, the main parts or components involved in the figures are numbered. The same number indicates the same or similar parts or components, which have basically the same function, but their specific size, shape, and structure in different drawings or embodiments are not necessarily the same.

Example 1

This embodiment is raw water treatment, and the content of dissolved organic carbon (DOC) in the water to be treated is 2-10 mg/L. Conventional coagulation membrane treatment process (conventional equipment including independent coagulation unit, precipitation unit and membrane treatment unit) is adopted. Continue to add aluminum salt coagulant, calculated as aluminum, 5mg/L per day. Among them, the mechanical stirring is fast rotation (200rpm) 1min, slow rotation (50rpm) 15min. Pump the raw water into the coagulation tank, pass through the sedimentation tank, and then enter the membrane tank at a rate of 1m ³ /h. The hydraulic retention time in the membrane tank is 0.5h. The sludge is discharged through the sedimentation tank, and the frequency of sludge discharge is 3 days/time. After 30 days of continuous operation, the transmembrane pressure difference increased to 48kPa, and the removal rate of DOC in the effluent was 79%.

Example 2

This embodiment is raw water treatment, and the content of dissolved organic carbon (DOC) in the water to be treated is 2-10 mg/L. Short-flow process (conventional equipment including independent coagulation unit and membrane treatment unit) is adopted. Continue to add aluminum salt coagulant, calculated as aluminum, 5mg/L per day. Among them, the mechanical stirring is fast rotation (200rpm) 1min, slow rotation (50rpm) 15min. The raw water is pumped into the coagulation tank, and enters the membrane tank at a rate of 1m ³ /h, and the hydraulic retention time in the membrane tank is 0.5h. Continuous operation for 30 days, mud discharge frequency is 3 days/time. Stand still for 30 minutes each time the sludge is discharged, and open the sludge discharge valve at the bottom of the membrane tank to discharge half of the sediment. After 30 days of continuous operation, the transmembrane pressure difference increased to 42kPa, and the removal rate of DOC in the effluent was 81%.

Example 3

Referring to Fig. 1, in an exemplary embodiment of the present invention, an integrated membrane coagulation reactor includes: a membrane tank 1, a membrane module 2 and an aeration device 3 arranged in the same membrane tank; 1. The suction pump 4 is connected in series with the coagulant dosing tank 5 through the pipeline. The membrane module 2 is also connected with the vacuum pressure gauge 6 through pipelines. The reactor is also provided with a water outlet 7 of the membrane pool. A sludge discharge valve 8 is also provided at the bottom of the membrane pool 1 .

This embodiment is raw water treatment, and the content of dissolved organic carbon (DOC) in the water to be treated is 2-10 mg/L. Using the integrated membrane coagulation reactor and water treatment process of the present invention, as shown in Figure 1, the coagulant dosing tank 5 contains aluminum salt coagulant, and the membrane module 2 and the aeration device 3 are placed in the same membrane tank 1 Inside.

The aluminum salt coagulant is continuously injected into the membrane pool 1 through the suction pump 4, calculated as aluminum at 5 mg/L per day. Among them, the aeration rate is 0.05L/min. Continuous operation for 30 days, mud discharge frequency is 10 days/time. Stand still for 30 minutes each time the mud is discharged, open the mud discharge valve 8, and discharge half of the sediment. The raw water is pumped into the membrane tank, and enters the membrane tank at a rate of 1m ³ /h, and the hydraulic retention time in the membrane tank is 0.5h. After 30 days of continuous operation, the transmembrane pressure difference increased to 38kPa, and the removal rate of DOC in the effluent was 86%.

Example 4

This embodiment is raw water treatment, and the content of dissolved organic carbon (DOC) in the water to be treated is 2-10 mg/L. Using the integrated membrane coagulation reactor and water treatment process of the present invention, as shown in Figure 1, the coagulant dosing tank 5 contains iron salt coagulant, and the membrane module 2 and the aeration device 3 are placed in the same membrane tank 1 Inside.

Continuously inject the iron salt coagulant into the membrane tank 1 at 5 mg/L per day in terms of iron. Among them, the aeration rate is 0.05L/min. Continuous operation for 30 days, mud discharge frequency is 10 days/time. Stand still for 30 minutes each time the mud is discharged, open the mud discharge valve 8, and discharge half of the sediment. The raw water is pumped into the membrane tank, and enters the membrane tank at a rate of 1m ³ /h, and the hydraulic retention time in the membrane tank is 0.5h. After 30 days of continuous operation, the transmembrane pressure difference increased to 39kPa, and the removal rate of DOC in the effluent was 84%.

Example 5

This embodiment is raw water treatment, and the content of dissolved organic carbon (DOC) in the water to be treated is 2-10 mg/L. Using the integrated membrane coagulation reactor and water treatment process of the present invention, as shown in Figure 1, the coagulant dosing tank 5 contains aluminum salt coagulant, and the membrane module 2 and the aeration device 3 are placed in the same membrane tank 1 Inside.

The aluminum salt coagulant is continuously injected into the membrane cell 1, calculated as aluminum at 5 mg/L per day. Among them, the aeration rate is 0.1L/min. Continuous operation for 30 days, mud discharge frequency is 10 days/time. Stand still for 30 minutes each time the mud is discharged, open the mud discharge valve 8, and discharge half of the sediment. The raw water is pumped into the membrane tank, and enters the membrane tank at a rate of 1m ³ /h, and the hydraulic retention time in the membrane tank is 0.5h. After 30 days of continuous operation, the transmembrane pressure difference increased to 36kPa, and the removal rate of DOC in the effluent was 85%.

Example 6

This embodiment is raw water treatment, and the content of dissolved organic carbon (DOC) in the water to be treated is 2-10 mg/L. Using the integrated membrane coagulation reactor and water treatment process of the present invention, as shown in Figure 1, the coagulant dosing tank 5 contains aluminum salt coagulant, and the membrane module 2 and the aeration device 3 are placed in the same membrane tank 1 Inside.

The aluminum salt coagulant is continuously injected into the membrane cell 1, calculated as aluminum at 5 mg/L per day. Among them, the aeration rate is 0.5L/min. Continuous operation for 30 days, mud discharge frequency is 10 days/time. Stand still for 30 minutes each time the mud is discharged, open the mud discharge valve 8, and discharge half of the sediment. The raw water is pumped into the membrane tank, and enters the membrane tank at a rate of 1m ³ /h, and the hydraulic retention time in the membrane tank is 0.5h. After 30 days of continuous operation, the transmembrane pressure difference increased to 31kPa, and the removal rate of DOC in the effluent was 82%.

Example 7

This embodiment is raw water treatment, and the content of dissolved organic carbon (DOC) in the water to be treated is 10-25 mg/L. Using the integrated membrane coagulation reactor and water treatment process of the present invention, as shown in Figure 1, the coagulant dosing tank 5 contains aluminum salt coagulant, and the membrane module 2 and the aeration device 3 are placed in the same membrane tank 1 Inside.

Continuously inject the aluminum salt coagulant into the membrane cell 1, calculated as aluminum at 10 mg/L per day. Among them, the aeration rate is 0.05L/min. Continuous operation for 30 days, mud discharge frequency is 10 days/time. Stand still for 30 minutes each time the mud is discharged, open the mud discharge valve 8, and discharge half of the sediment. The raw water is pumped into the membrane tank, and enters the membrane tank at a rate of 1m ³ /h, and the hydraulic retention time in the membrane tank is 0.5h. After 30 days of continuous operation, the transmembrane pressure difference increased to 33kPa, and the removal rate of DOC in the effluent was 87%.

Example 8

This embodiment is raw water treatment, and the content of dissolved organic carbon (DOC) in the water to be treated is 20-50 mg/L. Using the integrated membrane coagulation reactor and water treatment process of the present invention, as shown in Figure 1, the coagulant dosing tank 5 contains aluminum salt coagulant, and the membrane module 2 and the aeration device 3 are placed in the same membrane tank 1 Inside.

Continuously inject the aluminum salt coagulant into the membrane cell 1, 20mg/L per day in terms of aluminum. Among them, the aeration rate is 0.05L/min. Continuous operation for 30 days, mud discharge frequency is 10 days/time. Stand still for 30 minutes each time the mud is discharged, open the mud discharge valve 8, and discharge half of the sediment. The raw water is pumped into the membrane tank, and enters the membrane tank at a rate of 1m ³ /h, and the hydraulic retention time in the membrane tank is 0.5h. After 30 days of continuous operation, the transmembrane pressure difference increased to 27kPa, and the removal rate of DOC in the effluent was 92%.

Example 9

This embodiment is raw water treatment, and the content of dissolved organic carbon (DOC) in the water to be treated is 100-200 mg/L. Using the integrated membrane coagulation reactor and water treatment process of the present invention, as shown in Figure 1, the coagulant dosing tank 5 contains aluminum salt coagulant, and the membrane module 2 and the aeration device 3 are placed in the same membrane tank 1 Inside.

Continuously inject the aluminum salt coagulant into the membrane cell 1, calculated as aluminum at 30 mg/L per day. Among them, the aeration rate is 0.05L/min. Continuous operation for 30 days, mud discharge frequency is 10 days/time. Stand still for 30 minutes each time the mud is discharged, open the mud discharge valve 8, and discharge half of the sediment. The raw water is pumped into the membrane tank, and enters the membrane tank at a rate of 1m ³ /h, and the hydraulic retention time in the membrane tank is 0.5h. After 30 days of continuous operation, the transmembrane pressure difference increased to 37kPa, and the removal rate of DOC in the effluent was 88%.

Example 10

This embodiment is raw water treatment, and the content of dissolved organic carbon (DOC) in the water to be treated is 200-500 mg/L. Using the integrated membrane coagulation reactor and water treatment process of the present invention, as shown in Figure 1, the coagulant dosing tank 5 contains aluminum salt coagulant, and the membrane module 2 and the aeration device 3 are placed in the same membrane tank 1 Inside.

The aluminum salt coagulant is continuously injected into the membrane cell 1, calculated as aluminum at 50 mg/L per day. Among them, the aeration rate is 0.05L/min. Continuous operation for 30 days, mud discharge frequency is 10 days/time. Stand still for 30 minutes each time the mud is discharged, open the mud discharge valve 8, and discharge half of the sediment. The raw water is pumped into the membrane tank, and enters the membrane tank at a rate of 1m ³ /h, and the hydraulic retention time in the membrane tank is 0.5h. After 30 days of continuous operation, the transmembrane pressure difference increased to 41kPa, and the removal rate of DOC in the effluent was 93%.

Claims (10)

1. an integral type film coagulation reactor, including: membrane cisterna, and it is arranged at the membrane module in same membrane cisterna and aerator； Membrane cisterna is connected with coagulant dosage pond by pipeline in-line pumping pump；Mud valve it is additionally provided with bottom membrane cisterna；Described reaction Device is additionally provided with membrane cisterna outlet.

2. a kind of integral type film coagulation reactor as claimed in claim 1, it is characterised in that described aerator is arranged at membrane cisterna Interior bottom, distance top membrane module 10～50cm.

3. a kind of integral type film coagulation reactor as claimed in claim 1, it is characterised in that described aerator is boring aeration Manage or aeration head, and the level interval of aeration tube or aeration head is 5～50cm.

4. a kind of integral type film coagulation reactor as claimed in claim 1, it is characterised in that the aeration rate of described aerator >= 0.05L/min。

5. a kind of integral type film coagulation reactor as claimed in claim 1, it is characterised in that described membrane module is low-pressure membrane group Part, its form is immersion, and end is free end.

6. integral type film coagulation reactor as claimed in claim 1 a kind of, it is characterised in that described membrane module also by pipeline with Pressure vacuum gauge is connected.

7. an integral type film coagulation water processes membrane process method, it is characterised in that utilize the arbitrary described integral type of claim 1-6 Film coagulation reactor, configures finite concentration coagulant in coagulant dosage pond, bottom membrane cisterna in the case of aeration, logical Crossing suction pump and coagulant persistently pumps into membrane cisterna, pending water is directly injected into membrane cisterna, synchronizes to carry out coagulation and film in membrane cisterna Filtering, the water after filtration is discharged through membrane cisterna outlet；For ensureing treatment effect, pending water time of staying palpus in membrane cisterna ≥10min；When the 60～70% of flux depression to initial film flux, membrane module must be carried out Chemical cleaning.

8. integral type film coagulation water treatment technology as claimed in claim 7, it is characterised in that described coagulant is inorganic Coagulant, its kind is aluminum salt, iron salt coagulant or ferroaluminium composite coagulant.

9. integral type film coagulation water treatment technology as claimed in claim 7, it is characterised in that membrane cisterna in described process technique Interior water level exceeds membrane module 100～200cm.

10. integral type film coagulation water treatment technology as claimed in claim 7, it is characterised in that the spoil disposal frequency of described technique It it is 5～15 days/time；Every time during spoil disposal, stopping aeration, stand spoil disposal after 30min, water level decreasing is to membrane module.