CN101327967B - Membrane method lake water purification treatment process and device thereof - Google Patents

Abstract

The invention relates to a lake water purification treatment process and a device thereof, in particular to a lake water purification treatment process and a device thereof by adopting a membrane integration process. The device is characterized by comprising a pipeline type intelligent pretreatment system, a porous membrane filtering device and a low-pressure reverse osmosis device. The invention adopts the membrane integration technology to carry out post-treatment on the lake water, the effluent quality and the stability are superior to those of the traditional water treatment method, and the invention has the characteristics of small occupied area, large treatment capacity in unit time and high automation degree.

Description

Membrane lake water purification process and its device

technical field

The invention relates to a lake water purification process and a device thereof, in particular to a lake water purification process and a device thereof by adopting a membrane integration process.

Background technique

There are many lakes in our country, which are an important part of our country's water use. There are more than 24,800 lakes in the country, including more than 2,800 natural lakes with an area of more than 1 square kilometer. Among them, the larger freshwater lakes include Poyang Lake, Dongting Lake, Taihu Lake, Hongze Lake, Chaohu Lake, etc. These lakes have become important local water sources.

With the improvement of living standards, people's requirements for water quality are getting higher and higher, and traditional treatment methods have been difficult to meet the requirements. Residents living around the lake generally only conduct preliminary sedimentation treatment on the lake water. However, with the increasingly serious industrial pollution and domestic pollution, most lakes in my country are facing severe challenges, and the quality of lake water is declining day by day. Some lakes can no longer be directly used as domestic water. The demand for lake water purification treatment has increased.

Most of the lake water is slightly polluted water, and the overall water quality is good, so the treatment is relatively simple. The Chinese patent "Device and method for river and lake water treatment" (ZL200510002120.6) discloses a lake water treatment device with filter cartridges. This method is an improvement to the traditional water treatment process, but the overall filtration accuracy is not high, and it is difficult to meet the requirements of residential water. "Methods for Treating Polluted River or Lake Water" (200710024787.5) mentioned the method of adding hydrogen peroxide for treatment. The Japanese patent "WATER CLEANING METHOD" (JP2007245001) reported a method of bubbling into the water source to degrade trace organic matter, and then filter by microfiltration or ultrafiltration. The Japanese patent "WATERTREATMENT APPARATUS" (JP2007160158) reported a non-electric power water purification device. The box-type membrane container was placed in the bottom of the lake, and the pressure difference of the lake was used for membrane filtration to obtain cleaner water. A press presses it into a water reservoir in the ground. Therefore, the purification method of lake water has attracted great attention all over the world.

Contents of the invention

The object of the present invention is to provide a membrane method lake water purification treatment device and its treatment process which is quick and easy, occupies less floor area and has a high degree of automation in order to overcome some deficiencies in the existing lake water purification methods.

The technical solution of the present invention is: a membrane method lake water purification treatment device, which is characterized in that it is composed of a pipeline type intelligent pretreatment system, a porous membrane filtration device and a low-pressure reverse osmosis device. Among them, the pipeline-type intelligent pretreatment system refers to a device that automatically adds chemicals according to the characteristics of the influent water quality. The pipeline-type intelligent pretreatment system consists of a pressure sensing instrument, a branch pipe with a regulating valve, instrument, total organic carbon (TOC) sensing instrument, chemical addition interface, regulating valve and PLC control system, in which a filter screen is built in the branch pipe with regulating valve; a pressure sensing instrument is installed at the entrance of the pipeline, and then divided into two channels There is a branch pipe with a regulating valve, and a disc-type metal filter is built in each branch pipe. The pipeline after the two branch pipes merge is equipped with a pressure sensor, a turbidity sensor, a total organic carbon (TOC) sensor and a chemical agent. Adding interface, the agent adding interface is equipped with a regulating valve, and the PLC control system is used for communication between the above instruments and the regulating valve.

The PLC control system adopted in the pipeline type intelligent pretreatment system is composed of a data acquisition part and a unit control part. The data acquisition part in the above-mentioned PLC control system refers to the system online collection of pipeline operating parameters, and the parameters are the pressure at the pipeline inlet, the pressure at the pipeline outlet, the turbidity and the TOC value at the pipeline outlet; the unit control in the described PLC control system Part of it means that the system runs pre-programmed programs for automatic analysis based on the collected pressure, turbidity and TOC data, and starts or adjusts the corresponding valves to open or close the two branch pipes, adjust the addition of flocculants and oxidants The amount, so as to achieve intelligent preprocessing. The branch pipe with the regulating valve has a built-in filter screen, and the filter screen is located between the two regulating valves; the filter screen is preferably a disc-type stainless steel filter screen, and the filter screen has an aperture of 4-400 mesh, preferably 4-100 mesh.

The above-mentioned intelligent pretreatment control process is specifically: the initial state regulating valve 1, 3 (A, D) is opened, and the regulating valve 2, 4 (B, E) is closed. When the turbidity DIC is 5-100 NTU, the control valve 5 (F) is opened and Adjust to make the addition of flocculant 1-500ml/min; when the turbidity TOC is 5-100mg/L, open the regulating valve 6 (G) and adjust to make the addition of oxidant 1-500ml/min.

The flocculant is ferric chloride, ferrous sulfate or polyacrylamide; the oxidant is ozone, hydrogen peroxide or sodium hypochlorite.

The porous membrane filtration system is composed of a booster pump and a porous membrane module, wherein the porous membrane of the porous membrane module is a ceramic membrane, an organic membrane or a metal membrane, and the pore diameter of the porous membrane is 5 nm to 15 μm; the preferred membrane pore diameter range is 20 to 10 μm. 800nm; The low-pressure reverse osmosis device is composed of a high-pressure pump and a reverse osmosis membrane module. The reverse osmosis membrane material is preferably aromatic polyamide or cellulose acetate.

The present invention also provides a membrane-based lake water purification process, the specific steps of which are as follows: the lake water is input into a pipeline-type intelligent pretreatment system by using a pressure-driven device, and the effluent from the pipeline enters the porous membrane filtration system and is filtered by a porous membrane, and the resulting infiltrated water is After reaching the standard of ordinary tap water, the effluent is pumped into a low-pressure reverse osmosis device to prepare direct drinking water.

In the lake water input pipeline type intelligent pretreatment system, the pressure at the inlet and outlet of the pipeline is 0.01-0.5MPa, the amount of flocculant added is 1ml/min-500ml/min, and the amount of oxidant added is 1ml/min-500ml/min .

The technical parameters of the porous membrane filtration process described therein are operating pressure 0.01-0.5 MPa, membrane surface flow velocity 0.01-5 m/s; preferred operating pressure is 0.05-0.25 MPa, and preferred membrane surface flow velocity is 0.05-1 m/s.

The technological parameter of the low-pressure reverse osmosis process described therein is an operating pressure of 0.5-2.5 MPa, and a preferred operating pressure is 0.5-1.5 MPa.

The pumping of the permeated water from the porous membrane into the low-pressure reverse osmosis device means that the permeated water from the porous membrane is input into the low-pressure reverse osmosis device through a booster pump. Effective removal.

An intermediate buffer system (tank) can be added between the porous membrane filtration device and the reverse osmosis membrane device, part of the outlet water of the porous membrane filtration device can be used as tap water, and the other part can be used as the inflow of the reverse osmosis device.

The membrane method lake water purification process of the present invention can be extended to the purification of other surface waters (such as spring water and river water).

Beneficial effect:

The present invention adopts pipeline-type intelligent pretreatment system and membrane integration technology to purify lake water, which has great advantages:

(1) Compared with the traditional water purification method, the present invention has the characteristics of small footprint and large processing capacity per unit time. Traditional water purification methods mainly use pre-sedimentation tanks for water pretreatment. Since sand and other media are used to filter flocs, it usually takes a long time for flocculation and sedimentation to achieve good results, and the treatment capacity per unit time is small. However, the pipeline-type intelligent pretreatment system of the present invention occupies only 2% to 5% of the traditional pretreatment tank, and the flocculation and filtration operate continuously, and the unit processing capacity is large.

(2) The present invention adopts the membrane integration technology to post-treat the lake water, and the effluent water quality and stability are better than traditional water treatment methods. The effluent quality of traditional flocculation sedimentation combined with coarse filtration such as sand filtration is poor and unstable. If there is interference in the system, there may be fine submicron impurity particles in the effluent. The technology of the present invention first adopts the porous membrane to filter the pretreated effluent, and these fine particles do not exist in the effluent water quality, and the water quality and stability are greatly improved.

(3) The present invention realizes the quality-based use function of lake water in a brief process. The permeate effluent treated by the porous membrane can be used as tap water, and the subsequent low-pressure reverse osmosis effluent can produce direct drinking water, which is very practical in some specific occasions.

Description of drawings

Figure 1 is a block diagram of the membrane lake water purification process.

Figure 2 is a schematic diagram of a pipeline-type intelligent pretreatment system; in the figure, A-regulating valve 1, B-regulating valve 2, C-filter, D-regulating valve 3, E-regulating valve 4, F-regulating valve 5, G-Regulating valve 6, H-Flocculant adding pipeline, I-Oxidant adding pipeline; 1-Pressure sensing instrument, 2-Turbidity sensing instrument, 3-TOC sensing instrument, 4-Pressure sensing instrument, 5-PLC control system.

Figure 3 is a schematic diagram of the membrane lake water treatment system; in the figure, J-water delivery pump, K-increasing pressure pump, L-high pressure pump, M-porous membrane module, N-low pressure reverse osmosis membrane module; 6-lake water, 7-tap water , 8- Straight drinking water.

Detailed ways

The present invention is further described below in conjunction with embodiment.

Example 1

As shown in accompanying drawings 1 and 3, the process of the present invention mainly comprises three units of pipeline type intelligent pretreatment system (as shown in Figure 2), porous membrane and low-pressure reverse osmosis, and is connected with related equipment. The lake water used comes from Xuanwu Lake, and the filter mesh used has a pore size of 10 mesh.

When the system is powered on, water starts to flow in. Initially, the reading of the pressure PIC(4) at the water inlet is 0.1MPa, the reading of the pressure PIC(1) at the water outlet is 0.09MPa, the turbidity DIC(2) is 26.0NTU, and the TOC(3) is 4.0mg/L. At this time, adjust the opening of regulating valves 1 to 6 according to the PLC automatic control system: regulating valves 1 and 3 (A, D) are opened, regulating valves 2 and 4 (B, E) are closed, regulating valve 5 (F) is opened and Automatically adjust to make the addition of flocculant FeCl ₃ 5ml/min, and the regulating valve 6 (G) is closed.

The porous membrane used is a commercially available 19-channel alumina ceramic membrane with a pore size of 200 nm, an operating pressure of 0.15 MPa, a membrane surface flow rate of 1 m/s, a filtration temperature of 23 °C, and a permeation flux of 410 L·m ^-2 ·h ^-1 . Turbidity is 0.08NTU, TOC is 1.4mg/L. meet drinking water standards.

Roll-type low-pressure reverse osmosis membrane is used for deep purification of the effluent treated by the porous membrane. The water to be treated is pressurized to 0.7MPa by a booster pump and enters the low-pressure reverse osmosis membrane system. The permeation flux is 15L·m ^-2 ·h ^-1 , 60% of the intercepted dope is circulated. Finally, after low-pressure reverse osmosis treatment, the removal rate of divalent ions in the system reached 99.5%, the divalent ions in the effluent were less than 10mg/L, and the water quality indicators reached the commercially available pure water standards.

Example 2

As shown in accompanying drawings 1 and 3, the process of the present invention mainly comprises three units of pipeline type intelligent pretreatment system (as shown in Figure 2), porous membrane and low-pressure reverse osmosis, and is connected with related equipment. The lake water used comes from Xuanwu Lake, and the filter mesh used is 30 mesh.

The system starts to feed water when it is powered on. Initially, the reading of the pressure PIC(4) at the water inlet is 0.2MPa, the reading of the pressure PIC(1) at the water outlet is 0.19MPa, the turbidity DIC(2) is 23.0NTU, and the TOC(3) is 15.0mg/L. At this time, adjust the opening of regulating valves 1 to 6 according to the PLC automatic control system: regulating valves 1 and 3 (A, D) are opened, regulating valves 2 and 4 (B, E) are closed, regulating valve 5 (F) is opened and Automatically adjust to make the addition of flocculant FeCl ₃ 4ml/min, open the regulating valve 6 (G) and adjust to make the addition of oxidant NaClO 3ml/min. After a certain period of filtration (15 days), when the reading of the pressure PIC(1) at the water outlet drops below 0.12MPa, the PLC automatically opens the regulating valves 2, 4 (B, E), and closes the regulating valves 1, 3 (A, D), normal operation, and remove and clean the filter screen at the same time.

The porous membrane used is a commercially available 37-channel alumina ceramic membrane with a pore size of 50 nm, an operating pressure of 0.2 MPa, a membrane surface flow rate of 0.2 m/s, a filtration temperature of 24 °C, and a permeation flux of 210 L·m ^-2 ·h ^-1 . The turbidity of the effluent is 0.1NTU, and the TOC is 3.4mg/L. meet drinking water standards.

Roll-type low-pressure reverse osmosis membrane is used for deep purification of the effluent treated by porous membrane. The water to be treated is pressurized to 1.0MPa by a booster pump and enters the low-pressure reverse osmosis membrane system. The permeation flux is 25L·m ^-2 ·h ^-1 , 50% of the intercepted dope is circulated. Finally, after low-pressure reverse osmosis treatment, the removal rate of divalent ions in the system reached 99.5%, the divalent ions in the effluent were less than 10mg/L, and the water quality indicators reached the commercially available pure water standards.

Example 3

As shown in accompanying drawings 1 and 3, the process of the present invention mainly comprises three units of pipeline type intelligent pretreatment system (as shown in Figure 2), porous membrane and low-pressure reverse osmosis, and is connected with related equipment. The lake water used comes from Taihu Lake, and the filter mesh used has a pore size of 80 mesh.

The system starts to feed water when it is powered on. Initially, the pressure PIC(4) at the water inlet reads 0.2MPa, the pressure PIC(1) at the water outlet reads 0.19MPa, the turbidity DIC(2) is 31.0NTU, and the TOC(3) is 25.0mg/L. At this time, according to the PLC automatic control system, adjust the opening of regulating valves 1 to 6: regulating valves 2 and 4 (B, E) are opened, regulating valves 1 and 3 (A, D) are closed, regulating valve 5 (F) is opened and Automatically adjust to make the addition of flocculant FeCl ₃ 100ml/min, open the regulating valve 6 (G) and adjust to make the addition of oxidant NaClO 80ml/min. After a certain period of filtration (12 days), when the reading of the pressure PIC(1) at the water outlet drops below 0.12MPa, the PLC automatically opens the regulating valves 1, 3 (A, D), and closes the regulating valves 2, 4 (B, E), normal operation, remove and clean the filter screen at the same time.

The porous membrane used is a commercially available hollow fiber organic membrane with a pore size of 500 nm, an operating pressure of 0.05 MPa, a membrane surface flow rate of 0.05 m/s, a filtration temperature of 23 °C, a permeation flux of 80 L·m ^-2 ·h ^-1 , and turbid water. The density is 0.1NTU, TOC is 3.6mg/L, which meets the standard of drinking water.

Roll-type low-pressure reverse osmosis membrane is used for deep purification of porous membrane treated water. The water to be treated is pressurized to 1.5MPa by a booster pump and enters the low-pressure reverse osmosis membrane system with a permeation flux of 30L·m ^-2 ·h ^-1 , 40% of the intercepted dope is circulated. Finally, after low-pressure reverse osmosis treatment, the removal rate of divalent ions in the system reached 99.5%, the divalent ions in the effluent were less than 10mg/L, and the water quality indicators reached the commercially available pure water standards.

Claims (11)

1. A membrane method lake water purification treatment device is characterized in that it is made up of a pipeline-type intelligent pretreatment system, a porous membrane filtration device and a low-pressure reverse osmosis device; wherein said pipeline-type intelligent pretreatment system consists of a pipeline, a pressure transmitter Sensing instrument, branch pipe with regulating valve, turbidity sensing instrument, total organic carbon (TOC) sensing instrument, agent adding interface, regulating valve and PLC control system, the pressure is installed at the inlet of the branch pipe with regulating valve The sensing instrument is then divided into two branch pipes with regulating valves. The pipeline after the two branch pipes merge is equipped with a pressure sensing instrument, a turbidity sensing instrument, a total organic carbon (TOC) sensing instrument and a chemical addition interface. A regulating valve is installed on the agent adding interface, and a PLC control system is used for communication between the above instruments and the regulating valve. 2. The device according to claim 1, characterized in that the built-in strainer in the branch pipe with the regulating valve, the strainer is located between the two regulating valves; the strainer is a disc type stainless steel strainer, the strainer aperture 4 to 400 mesh. 3. The device according to claim 2, characterized in that the aperture of the filter screen is 4-100 mesh. 4. device according to claim 1, it is characterized in that described PLC control system is made up of data acquisition part and unit control part; Wherein the data acquisition part in the PLC control system refers to system online acquisition pipeline operation parameter, and parameter is The pressure at the inlet of the pipeline, the pressure at the outlet of the pipeline, the turbidity and TOC value at the outlet of the pipeline, the unit control part of the PLC control system means that the system runs the pre-programmed program according to the collected pressure, turbidity and TOC data. Automatically analyze, and start or adjust the corresponding valves to open or close the two branch pipes, adjust the amount of flocculant and oxidant added, so as to realize intelligent pretreatment. 5. The device according to claim 4, characterized in that said flocculant is ferric chloride, ferrous sulfate or polyacrylamide; said oxidizing agent is ozone, hydrogen peroxide or sodium hypochlorite. 6. The device according to claim 1, wherein the porous membrane filtration device is composed of a booster pump and a porous membrane assembly, wherein the porous membrane of the porous membrane assembly is a ceramic membrane, an organic membrane or a metal membrane, and the porous membrane The pore size is 5nm to 15μm; the low-pressure reverse osmosis device is composed of a high-pressure pump and a reverse osmosis membrane module. 7. The device according to claim 6, characterized in that the membrane pore diameter of the porous membrane ranges from 20 to 800 nm. 8. A membrane method lake water purification treatment process utilizing the device described in claim 1, its specific steps are as follows: the lake water is input to the pipeline type intelligent pretreatment system by using a pressure drive device, and the pipeline outlet water enters the porous membrane filtration system and adopts porous membrane filtration , the resulting infiltrated effluent reaches the standard of ordinary tap water, and the effluent is pumped into a low-pressure reverse osmosis device to prepare direct drinking water. the 9. The process according to claim 8, characterized in that the lake water is input into a pipeline-type intelligent pretreatment system, the pressure at the inlet and outlet of the pipeline is 0.01-0.5MPa, the amount of flocculant added is 1ml/min-500ml/min, and the oxidant Adding amount is 1ml/min～500ml/min. 10. The process according to claim 8, characterized in that the process parameter of the porous membrane filtration process is an operating pressure of 0.01 to 0.5 MPa, and a membrane surface velocity of 0.01 to 5 m/s; the process parameter of the low-pressure reverse osmosis process is The operating pressure is 0.5-2.5 MPa, and the circulation volume of the dope intercepted in the reverse osmosis process is controlled at 20-90%. 11. The process according to claim 10, wherein the process parameters of the porous membrane filtration process are characterized in that the operating pressure is 0.05～0.25MPa, and the membrane surface velocity is 0.05～1m/s; the process parameters of the low-pressure reverse osmosis process The operating pressure is 0.5~1.5MPa. the

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