A device for purifying car wash water

Abstract

The application discloses a device for purifying car washing water, which comprises a primary stripping tank, a secondary stripping tank, a tertiary stripping tank, a defoaming device and a water storage tank. The primary stripping tank is provided with a pipeline A at the bottom for entering the middle part of the secondary stripping tank. The secondary stripping tank is provided with a pipeline B at the bottom for entering the middle part of the tertiary stripping tank. The tertiary stripping tank is provided with a pipeline C at the bottom for entering the water storage tank. The primary stripping tank, the secondary stripping tank and the tertiary stripping tank are all provided with aeration elements at the bottom and are all communicated with the inlet end of the defoaming device through a defoaming pipe at the top. The defoaming device is provided with a defoaming pipe at the bottom. The device adopts a pure physical three-stage stripping process, can efficiently and stably remove LAS, emulsified oil stains and surface active substances which are difficult to be biodegraded in the car washing wastewater, does not need to add special demulsifying agents in the whole process, does not produce chemical by-products, does not cause secondary pollution, and the effluent water quality is stable and reliable. The defoaming device is arranged in a matched mode, and the mechanical shearing combined with the gravity effect is used to realize rapid elimination of foams.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a device for purifying car wash water. Background Technology

[0002] With the continuous growth of motor vehicle ownership in my country, the car wash industry has become one of the major water users and sources of wastewater discharge in cities. Statistics show that a single car wash typically uses 50-150 liters of water, with large car washes consuming over 10 tons of water per day. Car wash wastewater contains large amounts of pollutants such as silt, oil, surfactants (LAS), organic matter, and heavy metals. Direct discharge not only results in a huge waste of water resources but also causes long-term pollution of soil and surface water bodies. Under the dual pressure of increasingly stringent environmental policies and rising water resource fees, wastewater recycling has become an essential requirement for the industry.

[0003] The current mainstream process route is "pretreatment + coagulation sedimentation + filtration + disinfection". This process is mature, stable, reliable, and requires low investment, but it has limited effectiveness in removing anionic surfactants, volatile organic compounds, and some dissolved pollutants. This process is also prone to problems such as foam residue, viscous effluent, and odors after reuse. Some high-end equipment uses traditional membrane separation technology, which can achieve deep reuse, but generally suffers from high investment, large equipment size, susceptibility to clogging, frequent cleaning, and complex operation and maintenance.

[0004] In recent years, researchers both domestically and internationally have conducted extensive research on the removal of surfactants from car wash wastewater. Chinese patent CN117069336A discloses a car wash wastewater treatment device, including an oil separator, a surfactant removal mechanism, an organic matter filtration mechanism, a sterilization mechanism, and a clear water tank. The surfactant removal mechanism comprises multiple sequentially connected purification tanks, an aeration disc, an air compressor, a sludge discharge tank, and a sludge scraper. The connecting channels between adjacent purification tanks are arranged in an alternating, staggered manner. This device uses air flotation combined with sludge scraping to remove surfactants. Although it achieves multi-stage purification, it still relies on the mechanical scraper to remove floating foam.

[0005] Chinese patent CN201037125Y discloses a detergent removal device for car wash wastewater. This device consists of an aeration tank and a defoamer. The aeration tank has aeration bubble heads at the bottom, and the defoamer has motor-driven bubble-cutting blades. It can remove detergent without chemical additives, with a detergent removal efficiency of 80%–95%. However, this device only uses a single-stage aeration tank, limiting its LAS removal capacity, and it lacks a membrane separation unit, making it difficult to meet reuse standards for the effluent turbidity and suspended solids.

[0006] Chinese patent CN208361978U discloses an MBR membrane device for treating and reusing urban car wash wastewater. It includes a conditioning sedimentation zone, an oil-water separation zone, and an MBR zone connected in sequence. The device utilizes the MBR membrane to retain biochemically activated sludge bacteria, thereby improving biochemical efficiency and reducing floor space. Although this device incorporates membrane separation technology, its MBR zone primarily relies on biochemical treatment (activated sludge process), which has limited tolerance to LAS and surfactants. The membrane modules are in direct contact with high-concentration pollutant loads, making them prone to severe membrane fouling, requiring frequent chemical cleaning, and resulting in high operation and maintenance costs.

[0007] In summary, although there are research reports on the use of multi-stage series aeration for LAS removal and car wash wastewater treatment devices that integrate functions such as air flotation and defoaming, the following technical problems still exist: First, the LAS removal rate of two-stage series aeration is not high enough (about 86.5%), making it difficult to consistently meet the LAS ≤ 0.5 mg / L limit requirement in the "Water Quality Standard for Urban Wastewater Reuse for Miscellaneous Uses" (GB / T18920-2020); Second, existing air flotation methods often require the use of sludge scrapers or chemical defoamers, which leads to complex operation and maintenance or chemical residue problems. Summary of the Invention

[0008] The purpose of this invention is to provide a device for purifying car wash water, addressing the technical problems described in the background art.

[0009] The technical solution of the present invention: A device for purifying car wash water includes a primary stripping tank, a secondary stripping tank, a tertiary stripping tank, a defoamer, and a water storage tank. The primary stripping tank has a pipe A installed at its bottom that leads to the middle of the secondary stripping tank. The secondary stripping tank has a pipe B installed at its bottom that leads to the middle of the tertiary stripping tank. The tertiary stripping tank has a pipe C installed at its bottom that leads to the water storage tank. Aeration elements are distributed at the bottom of the primary, secondary, and tertiary stripping tanks. The tops of each tank are connected to the inlet of the defoamer via foam guide pipes. The defoamer has a foam outlet pipe installed at its bottom.

[0010] The aeration element includes several branch pipes installed at the bottom of the primary stripping tank, the secondary stripping tank and the tertiary stripping tank respectively, as well as aeration heads installed on the corresponding branch pipes, and a main pipe connected to all the branch pipes. The main pipe is connected to an aeration blower.

[0011] The defoamer includes a cylinder, a stirrer, and a motor. The stirrer is located inside the cylinder, and the motor is fixedly installed at the top of the cylinder and drives the stirrer to rotate. An air outlet pipe is connected to the top.

[0012] It also includes a flocculation tank and a sedimentation tank. The upper part of the flocculation tank is equipped with a pipe D that enters the bottom of the sedimentation tank. The upper part of the sedimentation tank is equipped with a pipe E that enters the middle of the primary stripping tank. The flocculation tank is equipped with an inlet pipe A, and a pipe mixer is installed on the inlet pipe A.

[0013] The inlet of the pipeline mixer is connected to a booster pump A and a metering pump via a tee connector.

[0014] The metering pump inlet is connected to a dosing tank.

[0015] The sedimentation tank is equipped with a sludge discharge pipe at the bottom, and the outlet end of the foam discharge pipe is connected to the sludge discharge pipe.

[0016] It also includes inlet pipe B, MBR membrane module, photocatalytic oxidation tank, booster pump B and photocatalytic oxidation module. Inlet pipe B is connected to the inlet of the first-stage stripping tank. The MBR membrane module is installed inside the third-stage stripping tank. The photocatalytic oxidation tank is connected in series on pipe C, and the inlet of pipe C is connected to the outlet of the MBR membrane module. The photocatalytic oxidation module is installed inside the photocatalytic oxidation tank. The booster pump B is installed on inlet pipe B.

[0017] The photocatalytic oxidation component includes a UV lamp assembly and a nano-TiO2 catalyst plate. The nano-TiO2 catalyst plate is vertically installed in the photocatalytic oxidation pool, and the UV lamp assembly is positioned next to the nano-TiO2 catalyst plate, with the two arranged in parallel.

[0018] The MBR membrane assembly includes a support frame and an MBR membrane disposed inside the support frame.

[0019] The beneficial effects of this invention are: The core of this invention employs a purely physical three-stage series stripping process, which can efficiently and stably remove LAS, emulsified oil, and surfactants that are difficult to biodegrade in car wash wastewater. The entire process requires no special demulsifiers, produces no chemical byproducts, avoids secondary pollution, and ensures stable and reliable effluent quality. By incorporating a defoamer, foam is rapidly eliminated through a combination of mechanical shearing and gravity, eliminating the need for chemical defoamers. This ensures safe and environmentally friendly operation with no chemical residues, reducing operating costs and effectively guaranteeing the quality of recycled water. For the flocculation sedimentation and three-stage stripping process configuration, this invention highly integrates four major functional units: flocculation, inclined tube sedimentation, three-stage stripping, and defoaming. The arrangement of each treatment link is compact and the space utilization rate is high. The whole set of equipment has a small footprint and low equipment investment. At the same time, daily operation and maintenance are simple and the overall cost of use is low.

[0020] For a three-stage stripping, MBR membrane, and photocatalytic oxidation process configuration, this invention adopts an innovative structure with pre-load reduction in the first and second stages of stripping and coupling of the third stage stripping with MBR membrane separation. This achieves solid-liquid separation while efficiently removing LAS and emulsified oil. The shared aeration element for both stripping and membrane scrubbing simplifies the piping process, reduces overall energy consumption, significantly reduces membrane fouling, extends membrane module lifespan, and improves equipment operational stability. The photocatalytic oxidation component can perform deep water treatment, thoroughly degrading residual recalcitrant organic matter and trace amounts of LAS, while also removing color and odor, further optimizing effluent quality and ensuring safe reuse.

[0021] This invention is based on the same core structure and designs two process configurations. It uses the same main components such as three-stage stripping, defoaming, and aeration. The modular design is reasonable and can be flexibly selected according to the influent water quality and effluent standards, making it applicable to a wider range of scenarios. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of another embodiment of the present invention; Figure 3 This is a schematic diagram of the defoamer of the present invention.

[0023] Attached reference numerals: 1-Primary stripping tank, 2-Secondary stripping tank, 3-Tertiary stripping tank, 4-Defoamer, 5-Water storage tank, 6-Pipe A, 7-Pipe B, 8-Pipe C, 9-Aeration element, 10-Foam outlet pipe, 11-Branch pipe, 12-Aeration head, 13-Main pipe, 14-Aeration blower, 15-Cylinder body, 16-Agitator, 17-Motor, 18-Air outlet pipe, 19-Foam guide pipe, 20-Flocculation tank, 21-Sedimentation tank, 22-Flocculant tank 23-Pipe D, 24-Inlet Pipe A, 25-Pipe Mixer, 26-T-connector, 27-Boost Pump A, 28-Metering Pump, 29-Dosing Tank, 30-Sludge Discharge Pipe, 31-Inlet Pipe B, 32-MBR Membrane Module, 33-Photocatalytic Oxidation Tank, 34-Photocatalytic Oxidation Module, 35-UV Lamp Assembly, 36-Nano TiO2 Catalytic Plate, 37-Support Frame, 38-MBR Membrane, 39-Boost Pump B. Detailed Implementation

[0024] Example 1 refer to Figure 1A device for purifying car wash water includes a primary stripping tank 1, a secondary stripping tank 2, a tertiary stripping tank 3, a defoamer 4, and a water storage tank 5. The bottom of the primary stripping tank 1 is equipped with a pipe A6 that enters the middle of the secondary stripping tank 2. The bottom of the secondary stripping tank 2 is equipped with a pipe B7 that enters the middle of the tertiary stripping tank 3. The bottom of the tertiary stripping tank 3 is equipped with a pipe C8 that enters the water storage tank 5. Aeration elements 9 are evenly distributed at the bottom of the primary stripping tank 1, the secondary stripping tank 2, and the tertiary stripping tank 3. The tops of each are connected to the inlet end of the defoamer 4 through foam guide pipes 19. The bottom of the defoamer 4 is equipped with a foam outlet pipe 10.

[0025] The aeration element 9 includes several branch pipes 11 installed at the bottom of the primary stripping tank 1, the secondary stripping tank 2 and the tertiary stripping tank 3 respectively, as well as aeration heads 12 installed on the corresponding branch pipes 11, and a main pipe 13 connected to all the branch pipes 11. The main pipe 13 is connected to an aeration blower 14.

[0026] This invention employs a three-stage stripping process. By adjusting the aeration volume and gas-liquid ratio of the aeration element 9, the gas-liquid contact area and mass transfer efficiency are increased, thereby enhancing the stripping strength. Based on the principle of purely physical gas-liquid separation, anionic surfactants (LAS), emulsified oil, various surfactants, and volatile organic compounds that are difficult to biodegrade in car wash wastewater are efficiently transferred from the liquid phase to the gas phase, achieving deep separation and stable removal of characteristic pollutants.

[0027] The three-stage stripping process of this invention does not require the addition of special demulsifiers or surfactants, does not produce chemical reaction byproducts, and has no risk of chemical residues or secondary pollution. It has a stable and reliable removal effect on LAS and emulsified oil stains, simple operating conditions, convenient maintenance, and is safe and environmentally friendly. It is a core key link to ensure that car wash wastewater meets standards for reuse after treatment.

[0028] refer to Figure 3 The defoamer 4 includes a cylinder 15, a stirrer 16 and a motor 17. The stirrer 16 is located inside the cylinder 15, and the motor 17 is fixedly installed at the top of the cylinder 15 and drives the stirrer 16 to rotate. An air outlet pipe 18 is connected to the top.

[0029] In this invention, the defoamer 4 is used to eliminate bubbles generated by the three-stage defoaming process. Specifically, a large amount of foam is generated during the operation of the three-stage defoaming process. The foam is collected and introduced into the cylinder 15 by the foam guide tube 19. Relying on the multiple coupling effects of mechanical shearing, airflow disturbance and gravity foam breaking, the foam is quickly broken, eliminated and separated from the gas. The defoaming process is entirely physical and does not require the addition of defoaming agents.

[0030] In this invention, the water storage tank 5 is used to store the effluent after the three-stage blow-off treatment, so that it can be reused for car washing.

[0031] Example 2 It also includes a flocculation tank 20 and a sedimentation tank 21. The upper part of the flocculation tank 20 is equipped with a pipe D22 that enters the bottom of the sedimentation tank 21. The upper part of the sedimentation tank 21 is equipped with a pipe E23 that enters the middle of the primary stripping tank 1. The flocculation tank 20 is equipped with an inlet pipe A24, and a pipe mixer 25 is installed on the inlet pipe A24.

[0032] The inlet end of the pipeline mixer 25 is connected to a booster pump A27 and a metering pump 28 via a tee connector 26.

[0033] The metering pump 28 is connected to a dosing tank 29 at its inlet. The metering pump 28 facilitates the recording and control of flow rate, while the dosing tank 29 facilitates the addition of materials.

[0034] The sedimentation tank 21 is equipped with a sludge discharge pipe 30 at the bottom, and the outlet end of the foam discharge pipe 10 is connected to the sludge discharge pipe 30.

[0035] In this embodiment, the flocculation tank 20, sedimentation tank 21, primary stripping tank 1, secondary stripping tank 2, tertiary stripping tank 3 and defoamer 4 can be installed in a centralized manner, which can reduce space occupation.

[0036] In this embodiment, the arrangement of the pipeline mixer 25 and the dosing tank 29 facilitates the addition of PAC (polyaluminum chloride) into the pipeline mixer 25, and utilizes the turbulent water flow in the pipeline to achieve rapid and homogeneous mixing of the reagent and wastewater. The flocculation tank 20 is designed to facilitate the flocculation treatment of the mixed wastewater. Specifically, through the flocculation reaction, suspended particles, colloidal impurities, and fine emulsified pollutants in the water are destabilized and aggregated to form dense, settleable flocs.

[0037] In this embodiment, the sedimentation tank 21 is an inclined tube sedimentation tank. The inclined tube sedimentation tank is designed to facilitate the entry of wastewater after flocculation into the inclined tube sedimentation tank. Relying on the principle of shallow pool sedimentation and inclined tube rectification and separation, it can efficiently intercept and remove suspended solids, flocs and other substances in the water, greatly reducing the pollution load of suspended solids and colloidal particles in the influent of subsequent processes, and providing a pre-treatment water quality guarantee for the stable operation of the downstream three-stage stripping process and the reuse of wastewater that meets the standards.

[0038] The solution used in this embodiment for treating car wash wastewater includes the following steps: S1: Car wash wastewater flocculation sedimentation separation treatment: The pretreated car wash wastewater is sent to the pipeline mixer 25 through the lift pump A27, and polyaluminum chloride is added to the pipeline mixer 25 through the dosing tank 29 for mixing. The mixed car wash wastewater enters the flocculation tank 20 for flocculation reaction. The car wash wastewater after flocculation reaction enters the inclined tube sedimentation tank for mud-water separation to obtain supernatant and sludge. The sludge is discharged through the sludge discharge pipe 30, and the supernatant enters the stripping unit. S2: Stripping treatment. In the stripping unit, the supernatant enters the primary stripping tank 1, the secondary stripping tank 2 and the tertiary stripping tank 3 in sequence for three-stage series stripping treatment. The effluent enters the water storage tank 5 for reuse, and the generated foam enters the defoamer 4. S3: Defoaming treatment. Inside the defoamer 4, the motor 17 drives the agitator 16 to rotate, performing defoaming treatment on the foam by shearing, airflow disturbance and gravity defoaming. The generated gas is discharged through the air outlet pipe 18, and the generated defoaming water is discharged through the foam outlet pipe 10 and the mud discharge pipe 30 in sequence.

[0039] The following table shows the effect of treating car wash wastewater using the solution in this embodiment. Please refer to Table 1 for details: Table 1. Treatment effect of a car wash water

[0040] Based on the data on the treatment effect of a car wash water shown in Table 1, it can be seen that this treatment process has a significant removal effect on various pollutants, and all water quality indicators after treatment meet the prescribed limits. Specific analysis is as follows: pH value: 7.62 before treatment and 7.89 after treatment, both within the standard limit range of 6-9, and the change was not significant, indicating that the treatment process had little impact on the acidity and alkalinity of the water.

[0041] Turbidity: 81 NTU before treatment, reduced to 3 NTU after treatment, far below the limit of 5 NTU, with a removal rate of approximately 96.3%, indicating that the treatment process is very effective in removing suspended particulate matter.

[0042] BOD5 (five-day biochemical oxygen demand): 28 mg / L before treatment and 8 mg / L after treatment, which is lower than the limit of 10 mg / L. The removal rate is about 71.4%, indicating that organic pollutants in the water have been effectively degraded.

[0043] Ammonia nitrogen: 7.36 mg / L before treatment and 1.25 mg / L after treatment, which is far below the limit of 5 mg / L. The removal rate is about 83.0%, indicating that the denitrification effect is good.

[0044] Anionic surfactants: The concentration before treatment was 12.348 mg / L, and after treatment it was 0.329 mg / L, which is lower than the limit of 0.5 mg / L. The removal rate was as high as 97.3%, indicating that the removal of surfactants such as detergents was very thorough.

[0045] The solution adopted in this embodiment can efficiently purify car wash wastewater, and the treated water quality fully meets the discharge or reuse standards (limits), especially the removal effect on turbidity and anionic surfactants is the most outstanding.

[0046] Example 3 refer to Figure 2It also includes an inlet pipe B31, an MBR membrane module 32, a photocatalytic oxidation tank 33, a booster pump B39, and a photocatalytic oxidation component 34. The inlet pipe B31 is connected to the inlet of the first-stage stripping tank 1. The MBR membrane module 32 is installed inside the third-stage stripping tank 3. The photocatalytic oxidation tank 33 is connected in series on the pipe C8, and the inlet of the pipe C8 is connected to the outlet of the MBR membrane module 32. The photocatalytic oxidation component 34 is installed inside the photocatalytic oxidation tank 33, and the booster pump B39 is installed on the inlet pipe B31.

[0047] The photocatalytic oxidation component 34 includes a UV lamp group 35 and a nano TiO2 catalyst plate 36. The nano TiO2 catalyst plate 36 is vertically installed in the photocatalytic oxidation pool 33, and the UV lamp group 35 is correspondingly arranged on the side of the nano TiO2 catalyst plate 36. The two are arranged in parallel.

[0048] The MBR membrane module 32 includes a support frame 37 and an MBR membrane 38 disposed inside the support frame 37.

[0049] In this embodiment, the primary stripping tank 1, the secondary stripping tank 2, the tertiary stripping tank 3, the defoamer 4, and the photocatalytic oxidation tank 33 can be installed in a centralized manner, which can reduce space occupation.

[0050] In this embodiment, an MBR membrane module 32 is built into the three-stage stripping tank 3. The aeration has the dual functions of stripping enhancement and MBR membrane 38 scrubbing. While performing physical stripping, the MBR membrane 38 achieves efficient solid-liquid separation, retains microorganisms and fine suspended solids, and improves the clarity of the effluent.

[0051] This embodiment primarily utilizes physical processes, eliminating the need for specialized demulsifiers, producing no chemical byproducts, and causing no secondary pollution. It provides stable and reliable LAS removal while simultaneously mitigating membrane fouling at its source, extending membrane lifespan, and reducing maintenance complexity.

[0052] In this embodiment, the photocatalytic oxidation component 34 is mainly used to catalytically oxidize the effluent from the three-stage stripping tank 3. Specifically, the effluent treated by the aeration element 9 and MBR membrane 38 of the three-stage stripping tank 3 enters the photocatalytic oxidation tank 33. Under the synergistic effect of the photocatalytic material nano-TiO2 catalyst plate 36 and the ultraviolet light UV lamp group 35, the strong oxidizing free radicals ·OH in the water completely oxidize and decompose the anionic surfactant LAS into CO2 and H2O, preventing foam recurrence and making the effluent foam-free and non-sticky. At the same time, it effectively sterilizes, kills bacteria, viruses and algae, completely eliminates the odor of the water, and avoids the odor, mold, loss of shine and dust accumulation on the car body caused by reuse after car washing.

[0053] The solution used in this embodiment for treating car wash wastewater includes the following steps: A1: Aeration stripping treatment: The pretreated car wash wastewater is sequentially sent to the primary stripping tank 1 and the secondary stripping tank 2 for aeration stripping treatment to remove anionic surfactants, emulsified oil and volatile organic compounds from the wastewater. A2: MBR membrane 38 separation treatment: The effluent from the secondary stripping tank 2 is sent to the tertiary stripping tank 3, which contains the MBR membrane module 32. During the aeration stripping treatment, the MBR membrane 38 separation treatment is carried out to obtain the effluent from the MBR membrane module 32. A3: Photocatalytic oxidation deep treatment, the effluent from the MBR membrane module 32 is sent into the photocatalytic oxidation tank 33. Under the synergistic effect of photocatalytic materials and ultraviolet light, the strong oxidizing free radicals ·OH in the water completely oxidize and decompose the anionic surfactant LAS into CO2 and H2O.

[0054] In steps A1 and A2, the foam generated in the primary stripping tank 1, the secondary stripping tank 2 and the tertiary stripping tank 3 is collected and sent to the defoamer 4 for defoaming treatment.

[0055] In step A2, the aeration element 9 in the tertiary stripping tank 3 is turned on to aerate and strip pollutants from the effluent of the secondary stripping tank 2, and the MBR membrane module 32 is air-washed using flowing water.

[0056] In step A3, the UV lamp group 35 is started, and under the irradiation of the UV lamp group 35 and the action of the nano TiO2 catalyst plate 36, the effluent of the MBR membrane module 32 is subjected to catalytic oxidation treatment.

[0057] Specifically, in this embodiment, after conventional pretreatment, the wastewater is pumped to the primary stripping tank 1 by a booster pump B39. The wastewater then sequentially enters the primary stripping tank 1, the secondary stripping tank 2, and the tertiary stripping tank 3. Neither the primary nor secondary stripping tanks 1 or 2 have membranes. The tertiary stripping tank 3 is equipped with an MBR membrane 38. After entering the tertiary stripping tank 3, the wastewater undergoes aeration and filtration via the MBR membrane 38. Aeration enables stripping and membrane module cleaning, while the MBR membrane 38 achieves solid-liquid separation. The effluent from the membrane enters the photocatalytic oxidation tank 33 for further photocatalytic oxidation treatment before flowing into the storage tank 5, which can be reused for car washing. The foam generated during stripping enters the defoamer 4 via the foam guide pipe 19 for treatment.

[0058] The following is a comparison table of the actual treatment effects of the device of the present invention on car wash water; see Table 2 for details: Table 2 Comparison of Actual Treatment Effects of Car Wash Water

[0059] Based on the data from the three test batches in Table 2, the effects of suspended solids, turbidity, and anionic surfactants on the influent and effluent were analyzed, and the results are as follows: The removal rate was calculated based on Table 2, and the results are shown in Table 3. Table 3 Removal Rate Reference Table

[0060] Specific removal rates for each batch: Experiment 1: Suspended solids 93.4%, turbidity 96.4%, anionic surfactant 98.3%. Experiment 2: Suspended solids 95.3%, turbidity 96.4%, anionic surfactant 95.5% Experiment 3: Suspended solids 94.3%, turbidity 95.8%, anionic surfactant 97.6%. The results of three sets of car wash wastewater tests showed that this process has excellent removal effects on suspended solids, turbidity, and anionic surfactants. The average removal rate of all three indicators was higher than 94%, with anionic surfactants achieving an average removal rate of 97.12%, turbidity 96.20%, and suspended solids 94.35%. The overall pollutant removal efficiency was at a high level. Although the influent water quality fluctuated significantly, the concentrations of various pollutants in the effluent were controlled in an extremely low range: suspended solids ≤6 mg / L, turbidity ≤4 NTU, and anionic surfactants ≤0.345 mg / L. The effluent water quality was stable and controllable. Even under high influent load conditions (106 mg / L suspended solids and 95 NTU turbidity in test 3), the removal rate of various pollutants remained above 94%.

Claims

1. A device for purifying car wash water, characterized in that: It includes a primary stripping tank (1), a secondary stripping tank (2), a tertiary stripping tank (3), a defoamer (4), and a water storage tank (5). The bottom of the primary stripping tank (1) is equipped with a pipe A (6) that enters the middle of the secondary stripping tank (2). The bottom of the secondary stripping tank (2) is equipped with a pipe B (7) that enters the middle of the tertiary stripping tank (3). The bottom of the tertiary stripping tank (3) is equipped with a pipe C (8) that enters the water storage tank (5). The bottom of the primary stripping tank (1), the secondary stripping tank (2), and the tertiary stripping tank (3) are all equipped with aeration elements (9). The top of each of them is connected to the inlet end of the defoamer (4) through a foam guide pipe (19). The bottom of the defoamer (4) is equipped with a foam outlet pipe (10).

2. The device for purifying car wash water according to claim 1, characterized in that: The aeration element (9) includes several branch pipes (11) installed at the bottom of the primary stripping tank (1), the secondary stripping tank (2) and the tertiary stripping tank (3), respectively, as well as aeration heads (12) installed on the corresponding branch pipes (11), and a main pipe (13) connected to the branch pipes (11), with an aeration blower (14) connected to the main pipe (13).

3. The device for purifying car wash water according to claim 1, characterized in that: The defoamer (4) includes a cylinder (15), a stirrer (16) and a motor (17). The stirrer (16) is located inside the cylinder (15), and the motor (17) is fixedly installed at the top of the cylinder (15) and drives the stirrer (16) to rotate. An air outlet pipe (18) is connected to the top.

4. The device for purifying car wash water according to claim 1, characterized in that: It also includes a flocculation tank (20) and a sedimentation tank (21). The upper part of the flocculation tank (20) is equipped with a pipe D (22) that enters the bottom of the sedimentation tank (21). The upper part of the sedimentation tank (21) is equipped with a pipe E (23) that enters the middle of the primary stripping tank (1). The flocculation tank (20) is equipped with an inlet pipe A (24). A pipe mixer (25) is installed on the inlet pipe A (24).

5. The device for purifying car wash water according to claim 1, characterized in that: The inlet end of the pipeline mixer (25) is connected to a booster pump A (27) and a metering pump (28) via a tee joint (26).

6. The device for purifying car wash water according to claim 5, characterized in that: The metering pump (28) is connected to a dosing tank (29) at its inlet.

7. The device for purifying car wash water according to claim 4, characterized in that: The sedimentation tank (21) is equipped with a sludge discharge pipe (30) at the bottom, and the outlet end of the foam discharge pipe (10) is connected to the sludge discharge pipe (30).

8. The device for purifying car wash water according to claim 1, characterized in that: It also includes inlet pipe B (31), MBR membrane module (32), photocatalytic oxidation tank (33), booster pump B (39) and photocatalytic oxidation component (34). Inlet pipe B (31) is connected to the inlet of the first-stage stripping tank (1). MBR membrane module (32) is installed inside the third-stage stripping tank (3). Photocatalytic oxidation tank (33) is connected in series on pipe C (8). The inlet of pipe C (8) is connected to the outlet of MBR membrane module (32). Photocatalytic oxidation component (34) is installed inside photocatalytic oxidation tank (33). Booster pump B (39) is installed on inlet pipe B (31).

9. The device for purifying car wash water according to claim 8, characterized in that: The photocatalytic oxidation component (34) includes a UV lamp group (35) and a nano TiO2 catalyst plate (36). The nano TiO2 catalyst plate (36) is vertically installed in the photocatalytic oxidation pool (33), and the UV lamp group (35) is correspondingly arranged on the side of the nano TiO2 catalyst plate (36). The two are arranged in parallel.

10. The apparatus for purifying car wash water according to claim 8, characterized in that: The MBR membrane module (32) includes a support frame (37) and an MBR membrane (38) disposed inside the support frame (37).

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