A reverse osmosis segmented low-pressure flushing system for treating automobile painting wastewater recycling water

Abstract

This invention provides a reverse osmosis segmented low-pressure flushing system for treating automotive painting wastewater, relating to the field of reverse osmosis flushing. The invention includes a primary reverse osmosis unit comprising a first-stage reverse osmosis section and a second-stage reverse osmosis section connected sequentially. The outlet end of the main flushing inlet pipe branches into a first-stage inlet pipe and a second-stage inlet pipe. The first-stage inlet pipe contains an adjustable-opening first-stage inlet valve body MCV-1, and the second-stage inlet pipe contains an adjustable-opening second-stage inlet valve body MCV-2. The first-stage outlet pipe contains a first-stage outlet valve body MV-1, and the second-stage outlet pipe contains a second-stage outlet valve body MV-2. This invention can better remove organic pollutants, colloids, bacteria, and scale from the surface of the reverse osmosis membrane, preventing these pollutants from accumulating on the membrane surface and clogging the membrane pores, ensuring a stable desalination rate, and obtaining better product water quality.

Description

Technical Field

[0001] This utility model relates to the field of reverse osmosis rinsing, and in particular to a reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater. Background Technology

[0002] Painting is a crucial step in automobile production. The painting process generates wastewater that is diverse in type, complex in composition, and high in pollutant concentration. Wastewater discharge is unpredictable, and the overall volume and quality of the wastewater vary significantly. Most existing painting wastewater treatment projects first collect different types of wastewater separately, perform physicochemical pretreatment, and then send them to a comprehensive wastewater equalization tank for biological treatment. Once the treated water meets discharge standards, it is directly discharged into the municipal sewer system. However, this approach still results in a waste of water resources.

[0003] To improve water resource utilization, a deep wastewater treatment process is adopted. The treated water from the biological system is filtered and adsorbed by a sand and carbon filter to remove suspended solids, colloids, and organic matter. Then, it passes through a softening resin tank to adsorb calcium and magnesium ions, preventing calcium sulfate, calcium carbonate, and magnesium carbonate precipitates in the reverse osmosis concentrate from exceeding their solubility and forming scale on the membrane surface, which is difficult to remove. The effluent from the softening resin tank is pressurized by a high-pressure pump, providing driving pressure. The membrane permeate flows into a pure water tank, while the concentrate is discharged to the wastewater treatment system for secondary treatment before being discharged. The permeate quality from the reverse osmosis membrane meets the water needs of the coating workshop, reducing the total amount of wastewater discharged and promoting a closed-loop industrial water recycling economy.

[0004] However, during long-term operation, various contaminants, such as colloids, microorganisms, inorganic scale, and metal oxides, gradually accumulate on the surface of reverse osmosis membrane systems. These deposits can cause a decline in the performance of the reverse osmosis membrane system. Regular low-pressure flushing is a simple and effective method for removing contaminants. Flushing the membrane surface with a large amount of clean water under low pressure and high flow conditions is highly effective in removing organic matter, bacteria, and calcium and magnesium ion scale.

[0005] However, conventional low-pressure flushing methods use raw water from reverse osmosis membranes for system-wide cleaning. Especially for deep treatment processes of coating wastewater, such system-wide flushing often fails to achieve the best cleaning results.

[0006] In summary, there is an urgent need for a segmented low-pressure flushing system based on reverse osmosis technology to improve the cleaning effect on reverse osmosis membranes. Utility Model Content

[0007] To address the aforementioned issues, the first aspect of this invention provides a reverse osmosis segmented low-pressure flushing system for treating automotive painting wastewater recycling. This system can better remove organic pollutants, colloids, bacteria, and scale from the surface of the reverse osmosis membrane, preventing these pollutants from accumulating on the membrane surface and clogging the membrane pores. It can also ensure a stable desalination rate and obtain better product water quality.

[0008] The segmented low-pressure flushing system provided by this utility model includes a first-stage reverse osmosis unit, which comprises a first-stage reverse osmosis unit and a second-stage reverse osmosis unit connected together; it also includes a flushing inlet main pipeline, the inlet end of which is connected to an external pump body for pumping in cleaning water, and a flow meter M installed in the flushing inlet main pipeline; the outlet end of the flushing inlet main pipeline branches into a first-stage inlet pipeline and a second-stage inlet pipeline, the outlet end of the first-stage inlet pipeline being connected to the inlet end or inlet pipeline of the first-stage reverse osmosis unit, and the second-stage inlet pipeline... The outlet end of the first inlet pipe is connected to the inlet end or inlet pipe of the second stage of reverse osmosis; the first inlet pipe is equipped with an adjustable inlet valve body MCV-1, and the second inlet pipe is equipped with an adjustable inlet valve body MCV-2; the first stage of reverse osmosis is connected to the external wastewater treatment system through a first outlet pipe, and the second stage of reverse osmosis is connected to the external wastewater treatment system through two outlet pipes; the first outlet pipe is equipped with an outlet valve body MV-1, and the second outlet pipe is equipped with an outlet valve body MV-2.

[0009] In one feasible embodiment, the flushing flow rate of the reverse osmosis section is 60-70 m³ / h. 3 / h.

[0010] In one feasible embodiment, the flushing flow rate of the second stage of reverse osmosis is 35-45 m³ / h. 3 / h.

[0011] In one feasible embodiment, the reverse osmosis section includes nine reverse osmosis membrane housings, each housing containing six reverse osmosis membranes, each membrane being eight inches in length.

[0012] In one feasible embodiment, the reverse osmosis second stage includes five reverse osmosis membrane housings, each housing containing six reverse osmosis membranes, and each reverse osmosis membrane being eight inches in length.

[0013] In one feasible embodiment, after flushing by the segmented low-pressure flushing system, the inlet pressure of the first and second reverse osmosis stages is 0.85–0.94 MPa, the permeate conductivity is 12–20 μS / cm, and the permeate flow rate is 31.5–33.0 m³ / cm. 3 / h.

[0014] In one feasible embodiment, the output current feedback of the inlet valve body MCV-1 is 4 to 20 mA.

[0015] In one feasible embodiment, the output current feedback of the two-stage inlet valve body MCV-2 is 4 to 20 mA.

[0016] In one feasible embodiment, the accuracy of both the first-stage inlet valve body MCV-1 and the second-stage inlet valve body MCV-2 is 1 to 3%.

[0017] In one feasible embodiment, the system also includes a PLC and a control panel connected to the PLC. The PLC is also connected to a flow meter M, a first-stage inlet valve body MCV-1, a first-stage outlet valve body MV-1, a second-stage inlet valve body MCV-2, and a second-stage outlet valve body MV-2, respectively.

[0018] The reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater provided by this utility model has the following features:

[0019] Beneficial effects:

[0020] 1) Stable desalination rate: Segmented low-pressure flushing can better remove organic pollutants, colloids, bacteria and dirt from the surface of the reverse osmosis membrane, preventing these pollutants from accumulating on the surface of the reverse osmosis membrane and clogging the membrane pores, thus ensuring a stable desalination rate and obtaining better product water quality.

[0021] 2) Reducing the impact of concentration polarization: The higher the concentration polarization factor, the greater the tendency for fouling and fouling on the surface membrane. When the ion product of sparingly soluble salts in the solution on the reverse osmosis membrane surface exceeds its solubility product, precipitation may form, increasing the osmotic pressure on the reverse osmosis membrane surface, thereby reducing the net driving pressure of the system and ultimately reducing the system's permeate flow. The segmented low-pressure flushing of this invention can reduce the impact of concentration polarization, maintain stable membrane flux, and maintain a high permeate flow.

[0022] 3) Reduce the frequency of chemical cleaning of reverse osmosis membranes: Surface fouling of reverse osmosis membranes exacerbates the performance degradation of the reverse osmosis membrane system. Permeate flow rate and desalination rate decrease over time, leading to deterioration of permeate water quality. The segmented low-pressure flushing of this invention can promptly and thoroughly remove fouling from the reverse osmosis membrane surface and alleviate significant performance degradation of the membrane system, extending the chemical cleaning cycle. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the reverse osmosis segmented low-pressure flushing system in this utility model.

[0024] Figure 2 This is a schematic diagram of the automotive painting wastewater treatment system of this utility model.

[0025] Figure Labels

[0026] Reverse osmosis stage 1

[0027] Reverse osmosis stage 2

[0028] Flushing main water inlet pipe 3

[0029] A section of water inlet pipe 4

[0030] Second-stage water inlet pipe 5

[0031] A section of water outlet pipe 6

[0032] Second-stage water outlet pipe 7

[0033] Pump body 8

[0034] Water tank 9 Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model. In the description of the present utility model, it should be noted that the terms "left side", "right side", "upper side", "lower side", "above", "below", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present utility model. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0037] Furthermore, in the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0038] The first aspect of this utility model provides a reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater, applicable to reverse osmosis systems in automotive painting wastewater treatment systems. (See reference...) Figure 1 The system includes a primary reverse osmosis unit, comprising a first-stage reverse osmosis unit 1 and a second-stage reverse osmosis unit 2 connected sequentially. It also includes a flushing inlet main pipe 3, the inlet of which is connected to an external pump body 8 for pumping in flushing water. A flow meter M is installed in the flushing inlet main pipe 3 to monitor the water flow rate. The outlet of the flushing inlet main pipe 3 branches into a first-stage inlet pipe 4 and a second-stage inlet pipe 5. The outlet of the first-stage inlet pipe 4 is connected to the inlet of the first-stage reverse osmosis unit 1 or its inlet pipe. The outlet of the second-stage inlet pipe 5 is connected to the inlet of the second-stage reverse osmosis unit 2 or its inlet pipe. The inlet pipe of the first-stage reverse osmosis unit 1 refers to the pipe connecting the previous process to the first-stage reverse osmosis unit 1, and the inlet pipe of the second-stage reverse osmosis unit 2 refers to the pipe connecting the first-stage reverse osmosis unit 1 and the second-stage reverse osmosis unit 2. The first inlet pipe 4 is equipped with an adjustable inlet valve body MCV-1, and the second inlet pipe 5 is equipped with an adjustable inlet valve body MCV-2. Adjustable opening means that the opening degree of the gate valves MCV-1 and MCV-2 can be adjusted, typically within a range of 0-100% with an accuracy of 1-3%. The first reverse osmosis section 1 is connected to an external wastewater treatment system via an outlet pipe 6, and the second reverse osmosis section 2 is connected to the external wastewater treatment system via two outlet pipes 7. The first outlet pipe 6 is equipped with an outlet valve body MV-1, and the second outlet pipe 7 is equipped with an outlet valve body MV-2. The first outlet pipe 6 and the second outlet pipe 7 are used to discharge the cleaned wastewater to the external wastewater treatment system.

[0039] As an explanation, after the reverse osmosis system of the automotive painting wastewater treatment system has been running continuously for 2-3 hours, the fouling on the surface of the reverse osmosis membranes in the first stage 1 and the second stage 2 will gradually increase, leading to a decrease in membrane element performance. Therefore, it is necessary to clean the first stage 1 and the second stage 2. During cleaning, the external pump 8 (low-pressure flushing pump) pumps cleaning water into the flushing inlet main pipe 3, while the flow meter M monitors the flow rate of the cleaning water flowing through the flushing inlet main pipe 3. Then, the first stage 1 of reverse osmosis is cleaned first. The first stage inlet valve body MCV-1 will adjust its opening according to the feedback from the flow meter M, so that the cleaning water flowing through the first stage inlet pipe 4 is maintained at a low pressure. Then, the cleaning water flows into the first stage 1 of reverse osmosis for cleaning. The wastewater generated after cleaning the first stage 1 of reverse osmosis will flow into the first stage outlet pipe 6. At this time, the first stage outlet valve body MV-1 will be fully opened, allowing the wastewater to flow into the external wastewater treatment system. After cleaning the first inlet pipe 4, the second inlet pipe 5 is cleaned. The opening of the second inlet valve body MCV-2 is adjusted according to the feedback from the flow meter M, so that the cleaning water flowing through the second inlet pipe 5 is maintained at a low pressure. Then the cleaning water flows into the second reverse osmosis stage 2 for cleaning. The wastewater generated after cleaning the second reverse osmosis stage 2 flows into the second outlet pipe 7. At this time, the second outlet valve body MV-2 is fully opened, allowing the wastewater to flow into the external wastewater treatment system. When the second reverse osmosis stage 2 is also cleaned, it will automatically switch to normal water flow. The results show that after flushing by the segmented low-pressure flushing system, the inlet pressure of the first reverse osmosis stage 1 and the second reverse osmosis stage 2 is 0.85-0.94 MPa, the permeate conductivity is 12-20 μs / cm, and the permeate flow rate is 31.5-33.0 m3 / h.

[0040] As a supplement, the segmented low-pressure flushing system also includes a PLC and a control panel connected to the PLC. The PLC is also connected to a flow meter M, a first-stage inlet valve MCV-1, a first-stage outlet valve MV-1, a second-stage inlet valve MCV-2, and a second-stage outlet valve MV-2. For example, the PLC adjusts the ratio of the first-stage inlet valve MCV-1 and the second-stage inlet valve MCV-2 according to the value of the flow meter M and the design program, and controls the opening and closing status of the first-stage outlet valve MV-1 and the second-stage outlet valve MV-2, thereby achieving the purpose of precisely adjusting the segmented cleaning flow.

[0041] In one specific embodiment, the flushing flow rate of the reverse osmosis stage 1 is 60-70 m³ / h. 3 / h. In another specific embodiment, the flushing flow rate of the second stage of reverse osmosis is 35-45m³ / h. 3 / h.

[0042] In one specific embodiment, the reverse osmosis stage 1 includes nine reverse osmosis membrane housings, each housing containing six reverse osmosis membranes, and each reverse osmosis membrane being eight inches in length. In another specific embodiment, the reverse osmosis stage 2 includes five reverse osmosis membrane housings, each housing containing six reverse osmosis membranes, and each reverse osmosis membrane being eight inches in length.

[0043] In one specific embodiment, the output current feedback of the first-stage inlet valve body MCV-1 is 4–20 mA. In another specific embodiment, the output current feedback of the second-stage inlet valve body MCV-2 is 4–20 mA.

[0044] The second aspect of this utility model also provides an automotive painting wastewater treatment system. See Figure 2 The system includes a physicochemical and biochemical treatment system, a sand and carbon filter, a softening resin tank, and a reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater, all connected in sequence. The outlet of the first reverse osmosis stage 1 is further provided with a product water pipeline, and the outlet of the second reverse osmosis stage 2 is further provided with two product water pipelines. Both the outlet of the first and second product water pipelines are connected to an external water tank 9.

[0045] In this embodiment, the first inlet valve body MCV-1 is a proportional regulating electric valve with analog output signal feedback (4-20mA current signal), and the first outlet valve body MV-1 is an electric valve with digital output signal. The second inlet valve body MCV-2 is a proportional regulating electric valve with analog output signal feedback (4-20mA current signal), and the second outlet valve body MV-2 is an electric valve with digital output signal.

[0046] The first stage of reverse osmosis (RO) consists of 9 membrane housings, each containing 6 8-inch anti-fouling low-pressure RO membranes, for a total of 54 low-pressure membranes. The second stage of RO consists of 5 membrane housings, each containing 6 8-inch anti-fouling low-pressure RO membranes, for a total of 30 low-pressure membranes. According to the RO membrane manufacturer's user manual and design specifications, the low-pressure flushing flow rate for a single 8-inch membrane housing is 6–9 m³ / h. 3 The flushing flow rate of the first stage of reverse osmosis is designed at 65m³ / h. 3 / h, the flushing flow rate of the first stage of reverse osmosis is designed to be 40m³ / h. 3 The low-pressure flushing program is programmed in the PLC software, and the flushing flow rate value for each segment is displayed on the control panel. The flushing flow rate value can be modified accordingly on the control panel.

[0047] Based on the operating characteristics of reverse osmosis membranes, low-pressure flushing is required when the reverse osmosis membrane system is started or every 2 hours of operation. The first-stage inlet valve MCV-1 and the second-stage inlet valve MCV-2 are linked to the flow meter M. When the low-pressure flushing conditions are met, the first-stage inlet valve MCV-1 opens and adjusts its opening in real time to maintain the flushing flow rate; the first-stage outlet valve MV-1 fully opens; and the external pump 8 (low-pressure flushing pump) operates. The low-pressure flushing time for the first stage of reverse osmosis (reverse osmosis) is set to 3 minutes, which can be modified on the touchscreen. After the first stage of reverse osmosis (reverse osmosis) is flushed, the second-stage inlet valve MCV-2 opens and adjusts its opening in real time to maintain the flushing flow rate; the second-stage outlet valve MV-2 fully opens; and the external pump 8 (low-pressure flushing pump) operates. The low-pressure flushing time for the second stage of reverse osmosis (reverse osmosis) is set to 3 minutes, which can be modified on the touchscreen.

[0048] The results show that after flushing by the segmented low-pressure flushing system, the inlet pressure of the reverse osmosis stage 1 and reverse osmosis stage 2 is 0.85–0.94 MPa, the permeate conductivity is 12–20 μS / cm, and the permeate flow rate is 31.5–33.0 m³ / h. A comparison of the process parameters between this invention and a conventional low-pressure flushing system is detailed in Table 1.

[0049] Table 1

[0050]

[0051]

[0052] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present utility model, and these improvements and substitutions should also be considered within the protection scope of the present utility model.

Claims

1. A reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater, characterized in that: It includes a first-stage reverse osmosis unit, which includes a first-stage reverse osmosis unit (1) and a second-stage reverse osmosis unit (2) connected in sequence; It also includes a flushing water inlet main pipe (3), the inlet end of which is connected to an external pump body, the pump body being used to pump in cleaning water, and a flow meter M in the flushing water inlet main pipe (3); the outlet end of the flushing water inlet main pipe (3) is branched into a first inlet pipe (4) and a second inlet pipe (5), the outlet end of the first inlet pipe (4) being connected to the inlet end or inlet pipe of the first reverse osmosis section (1), and the outlet end of the second inlet pipe (5) being connected to the inlet end or inlet pipe of the second reverse osmosis section (2); the first inlet pipe (4) is equipped with a first inlet valve body MCV-1 with adjustable opening, and the second inlet pipe (5) is equipped with a second inlet valve body MCV-2 with adjustable opening; The first stage of reverse osmosis (1) is connected to the external wastewater treatment system through a water outlet pipe (6), and the second stage of reverse osmosis (2) is connected to the external wastewater treatment system through two water outlet pipes (7); a water outlet valve body MV-1 is provided in the first water outlet pipe (6), and a water outlet valve body MV-2 is provided in the second water outlet pipe (7).

2. The reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater according to claim 1, characterized in that: The flushing flow rate of the reverse osmosis stage (1) is 60-70 m³ / h. 3 / h.

3. The reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater according to claim 1, characterized in that: The flushing flow rate of the second stage (2) of the reverse osmosis is 35-45 m³ / h. 3 / h.

4. The reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater according to claim 1, characterized in that: The reverse osmosis section (1) includes 9 reverse osmosis membrane housings, each housing containing 6 reverse osmosis membranes, each membrane being 8 inches in length.

5. The reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater according to claim 1, characterized in that: The reverse osmosis stage (2) includes 5 reverse osmosis membrane housings, each housing containing 6 reverse osmosis membranes, each membrane being 8 inches in length.

6. The reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater according to claim 1, characterized in that: After flushing by the aforementioned segmented low-pressure reverse osmosis flushing system, the inlet pressure of the first-stage reverse osmosis unit is 0.85–0.94 MPa, the permeate conductivity is 12–20 μS / cm, and the permeate flow rate is 31.5–33.0 m³ / cm. 3 / h.

7. The reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater according to claim 1, characterized in that: The output current feedback of the MCV-1 inlet valve body is 4-20mA.

8. The reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater according to claim 1, characterized in that: The output current feedback of the two-stage inlet valve body MCV-2 is 4-20mA.

9. The reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater according to claim 1, characterized in that: The accuracy of both the first-stage inlet valve body MCV-1 and the second-stage inlet valve body MCV-2 is 1-3%.

10. The reverse osmosis segmented low-pressure rinsing system for treating automotive painting wastewater according to claim 1, characterized in that: It also includes a PLC and a control panel connected to the PLC. The PLC is also connected to a flow meter M, a first-stage inlet valve body MCV-1, a first-stage outlet valve body MV-1, a second-stage inlet valve body MCV-2, and a second-stage outlet valve body MV-2, respectively.

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