Treatment method for fluorescent flaw detection cleaning wastewater

Abstract

The invention discloses a treatment method for fluorescent flaw detection cleaning wastewater, and belongs to the technical field of wastewater treatment. Fluorescence flaw detection cleaning wastewater is treated through a wastewater adjusting tank, a demulsification adjusting tank, an air floatation tank, a first pH adjusting tank, a Fenton oxidation tank, a second pH adjusting tank, an MCR membrane tank and an adsorption tank in sequence. Wherein the wastewater adjusting tank stabilizes water quality and water quantity; a demulsifier is added into the demulsification adjusting tank for demulsification; the air floatation tank realizes oil-water separation through flocculation reaction and air floatation treatment; deeply oxidizing organic matters in a Fenton oxidation pond; the pH adjusting tank is used for adjusting the pH to be neutral; the MCR membrane tank utilizes a hollow fiber ultrafiltration membrane to separate out suspended sludge; the adsorbent in the adsorption tank further reduces the COD of the wastewater to below the discharge standard. The whole technological process is simple, mature in technology, good in treatment effect and easy and convenient to operate and maintain.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a method for treating fluorescent flaw detection cleaning wastewater. Background Art

[0002] Fluorescence flaw detection is a method used to detect surface defects on components. The principle is to immerse the component in an oil-based fluorescent liquid, allowing it to adhere to the surface. The component is then drained and cleaned. Because water cannot completely clean the fluorescent liquid from the component's notch, it remains attached. Testing the fluorescent liquid can pinpoint the location of the notch.

[0003] However, the fluorescent penetrant cleaning process generates a certain amount of fluorescent cleaning wastewater, which contains large amounts of chemical components such as fluorescent powders and surfactants. Once these components enter natural water bodies, they are absorbed by aquatic plants and animals and, through the food chain, ultimately ingested by humans, posing a health hazard. Furthermore, the oils and surfactants in the wastewater form a film on the water surface during diffusion, preventing oxygen from reaching aquatic plants and animals, leading to their mortality and further polluting the aquatic environment. Further complicating matters, this wastewater contains a large amount of emulsifiers. Their function is to fully mix with the fluorescent penetrant, making it soluble in water and facilitating flushing. However, the presence of emulsifiers in the cleaning wastewater prevents oil droplets from agglomerating, remaining uniformly and stably in the aqueous solution. This significantly increases the difficulty of wastewater treatment.

[0004] However, conventional processes often only involve flocculation and demulsification, and the water produced by the flocculation process is separated from the mud and water only by gravity sedimentation. For example, the Chinese invention patent with authorization publication number CN104211209B discloses a method for treating fluorescent penetrant testing wastewater. However, fluorescent penetrant testing cleaning wastewater contains an oil phase, and the oil residue has a relatively low density, making it difficult to effectively separate it from water by gravity sedimentation. The utility model patent with authorization publication number CN205347046U discloses a fluorescent wastewater treatment system. This patent performs a main treatment process on the wastewater after demulsification treatment to achieve the designed discharge water quality, but the subsequent treatment process is too complicated, increasing the difficulty and cost of operation. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies in the prior art and provide a method for treating fluorescent flaw detection cleaning wastewater.

[0006] The specific technical solutions adopted in the present invention are as follows:

[0007] The present invention provides a method for treating fluorescent flaw detection cleaning wastewater, which comprises a wastewater regulating tank, an emulsion breaking regulating tank, an air flotation tank, a first pH regulating tank, a Fenton oxidation tank, a second pH regulating tank, an MCR membrane tank and an adsorption tank connected in sequence. The specific steps are as follows:

[0008] S1: The fluorescent flaw detection cleaning wastewater to be treated enters the wastewater regulating tank to stabilize the water quality and water volume;

[0009] S2: The stabilized wastewater enters the demulsification regulating tank where demulsifier is added for demulsification;

[0010] S3: The demulsified wastewater enters the flotation tank, which includes a flocculation reaction zone and an air flotation reaction zone arranged in sequence. A flocculant is added to the flocculation reaction zone, and the oil droplets in the wastewater mix with the flocculant to form oil residue flocs. The oil residue flocs enter the air flotation reaction zone for flotation treatment, and the oil residue flocs on the surface of the air flotation reaction zone are scraped off to complete oil-water separation.

[0011] S4: The effluent from the flotation reaction zone of the flotation tank first enters the first pH adjustment tank to adjust the pH to 2-3, and then enters the Fenton oxidation tank for Fenton reaction;

[0012] S5: The effluent from the Fenton oxidation tank enters the second pH adjustment tank to adjust the pH to 6-9;

[0013] S6: The effluent from the second pH regulating tank enters the MCR membrane tank, in which a hollow fiber ultrafiltration membrane is installed. The effluent from the second pH regulating tank passes through the hollow fiber ultrafiltration membrane to separate the suspended sludge, and the suspended sludge on the surface is scraped off to complete the mud-water separation.

[0014] S7: The effluent from the MCR membrane pool enters the adsorption pool, and an adsorbent for adsorbing reducing substances is added to the adsorption pool; in the adsorption pool, the COD of the wastewater drops below the discharge standard, and the wastewater treatment is completed.

[0015] Preferably, the amount of the demulsifier added is 1 to 2 mL / L.

[0016] Preferably, the flocculant is anionic polyacrylamide; the concentration of the anionic polyacrylamide is 0.5‰ to 1‰, and the addition amount is 2.5 to 5 ppm.

[0017] Preferably, a sulfuric acid solution is added into the first pH adjustment tank to adjust the pH value.

[0018] Preferably, ferrous sulfate and hydrogen peroxide solution for Fenton reaction are added into the Fenton oxidation tank.

[0019] Furthermore, the concentration of the hydrogen peroxide solution is 25% to 30%, and the added amount is 10 to 18 mL / L; the added amount of ferrous sulfate is 12.3 to 18.4 g / L.

[0020] Preferably, the second pH adjustment tank uses a sodium hydroxide solution with a volume concentration of 10% to adjust the pH.

[0021] Preferably, the pore size of the hollow fiber ultrafiltration membrane is less than 0.1 μm.

[0022] Preferably, the oil residue flocs in the flotation reaction zone of the flotation tank and the suspended sludge in the MCR membrane tank are collected together and then filtered using a screw filter press.

[0023] Preferably, the adsorbent added to the adsorption tank is activated carbon or adsorption resin; the added amount of the activated carbon is 0.7 to 1.5 g / L.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention firstly uses a demulsifier to accurately demulsify the emulsion according to the physical and chemical characteristics of the emulsion of the fluorescent flaw detection cleaning wastewater. This process has a very high demulsification efficiency and no secondary pollution is generated throughout the process. The operation process is also very simple and fast, laying a good foundation for subsequent wastewater treatment work.

[0026] (2) A flotation tank with a flocculation reaction zone and an air flotation reaction zone is used for the wastewater after demulsification. On the one hand, the small oil droplets after demulsification are converted into large-particle flocs through flocculation treatment, thereby further achieving oil-water separation; on the other hand, since the density of the flocs themselves is relatively light and the gravity sedimentation effect is relatively poor, the use of an air flotation device can attach a large number of micro-nano bubbles to the surface of the flocs, thereby making the flocs suspended on the surface of the wastewater, and completely achieving solid-liquid separation through a scraper. The whole process is fully separated in terms of oil-water and solid-liquid, thus avoiding adverse effects on subsequent processes;

[0027] (3) The Fenton process is used to deeply oxidize the wastewater after demulsification, which can convert the difficult-to-degrade large-molecule organic matter in the wastewater into small-molecule substances, and finally completely oxidize and decompose it, with high efficiency in treating soluble organic matter. The pH is then adjusted to neutral, and Fe(OH)3 precipitates are generated. MCR hollow fiber ultrafiltration membrane elements are used for filtration, with strong terminal security and effluent turbidity <1NTU.

[0028] (4) The activated carbon adsorption process is used to treat the water produced by the MCR membrane. The amount of activated carbon added is determined according to the influent water quality to meet the emission standards. The process is highly adjustable.

[0029] In general, the entire process provided by the present invention consists of three major steps: oxidative demulsification, advanced oxidation and deep adsorption. The process is simple and clear, the technology adopted is mature and reliable, and can provide a strong guarantee for the stable compliance of the effluent water quality. Daily operation and maintenance are also very simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Flow chart of the method for treating fluorescent flaw detection cleaning wastewater provided by the present invention;

[0031] In the figure: wastewater regulating tank 1, demulsification regulating tank 2, flotation tank 3, Fenton oxidation tank 4, first pH regulating tank 5-1, second pH regulating tank 5-2, MCR membrane tank 6, adsorption tank 7, screw filter press 8. DETAILED DESCRIPTION

[0032] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention may be combined accordingly, provided that there is no conflict between them.

[0033] like Figure 1 As shown, the present invention provides a method for treating fluorescent flaw detection cleaning wastewater. The method uses a wastewater regulating tank 1, an emulsion breaking regulating tank 2, an air flotation tank 3, a first pH regulating tank 5-1, a Fenton oxidation tank 4, a second pH regulating tank 5-2, an MCR membrane tank 6, and an adsorption tank 7, which are connected in sequence.

[0034] The wastewater regulating tank 1 is used to store the fluorescent flaw detection cleaning wastewater to be treated. In the wastewater regulating tank 1, the water quality and water volume of the wastewater to be treated in the entire system are stabilized.

[0035] The stabilized wastewater enters the demulsification regulating tank 2 where demulsifier is added for demulsification. The amount of demulsifier added is 1-2 mL / L. Those skilled in the art can select different demulsifiers and addition amounts according to the actual wastewater conditions.

[0036] After demulsification, the wastewater enters the flotation tank 3, which includes a flocculation reaction zone and a flotation reaction zone, arranged in sequence. A flocculant is added to the flocculation reaction zone, allowing oil droplets in the wastewater to mix with the flocculant to form large, low-density oil residue flocs. These oil residue flocs then enter the flotation reaction zone for flotation treatment, where they are scraped off the surface of the flotation reaction zone to complete oil-water separation. It should be noted that anionic polyacrylamide can be used as the flocculant, with a concentration of 0.5‰ to 1‰ and an addition level of 2.5 to 5 ppm. Those skilled in the art may also select other flocculants and their addition levels based on the actual wastewater conditions.

[0037] The effluent from the flotation reaction zone of flotation tank 3 first enters the first pH adjustment tank 5-1. A sulfuric acid solution (1:1) is added to the first pH adjustment tank 5-1 to adjust the wastewater pH to 2-3. The effluent then enters the Fenton oxidation tank 4. Ferrous sulfate and hydrogen peroxide solution are added to the Fenton oxidation tank 4 for the Fenton reaction. The Fenton reaction can generate a large amount of highly oxidizing ·OH, which is used to efficiently oxidize reducing substances in the water. The concentration of the hydrogen peroxide solution that can be used is 25% to 30%, and the addition amount is 10-18 mL / L. The addition amount of ferrous sulfate is 12.3-18.4 g / L, and those skilled in the art can adjust it based on the actual wastewater conditions.

[0038] The effluent from the Fenton oxidation tank 4 enters the second pH regulating tank 5-2. A sodium hydroxide solution with a volume concentration of 10% is added to the second pH regulating tank 5-2 to adjust the pH to 6-9.

[0039] After pH adjustment, the effluent from the second pH adjustment tank 5-2 enters the MCR membrane tank 6, which is equipped with a hollow fiber ultrafiltration membrane with a pore size of less than 0.1 μm for mud-water separation. Suspended sludge is separated by the hollow fiber ultrafiltration membrane and then scraped off the surface, completing the mud-water separation and ensuring the turbidity of the effluent.

[0040] The effluent from the MCR membrane tank 6 enters the adsorption tank 7, where an adsorbent for adsorbing reducing substances is added. In the adsorption tank 7, the COD content of the wastewater is reduced to below the discharge standard, completing wastewater treatment. It should be noted that the adsorbent added to the adsorption tank 7 can be activated carbon or adsorption resin.

[0041] In addition, the oil residue flocs in the flotation reaction zone of flotation tank 3 and the suspended sludge in MCR membrane tank 6 are collected and filtered using screw filter press 8. The screw filter press can reduce the moisture content and volume of the sludge, thereby reducing the cost and difficulty of subsequent transportation, storage, and disposal.

[0042] Example 1

[0043] This embodiment provides a method for treating fluorescent flaw detection cleaning wastewater, and the specific steps are as follows:

[0044] (1) After the untreated fluorescent flaw detection cleaning wastewater (raw water COD concentration is 12625 mg / L) in the wastewater regulating tank 1 is stabilized, it enters the demulsification reaction tank 2.

[0045] (2) Demulsification reaction tank 2 was added with demulsifier at 1 mL / L. In this embodiment, the demulsifier used was Yangjing produced by Anhui Zhonghuan Environmental Protection Technology Co., Ltd. After testing, the COD concentration of the wastewater after demulsification was 2948 mg / L.

[0046] (3) The effluent from the demulsification reaction tank 2 first enters the flocculation reaction zone in the flotation tank 3. Anionic polyacrylamide (flocculant) is added at a concentration of 1‰ at a rate of 4ppm to the flocculation reaction zone. The oil droplets in the wastewater react with the flocculant to form large, low-density oil residue flocs. The wastewater then enters the flotation reaction zone. The flotation reaction zone uses a gas-liquid mixing pump to dissolve air at high pressure. The generated micro-nano bubbles adhere to the oil residue flocs, which are suspended on the surface of the flotation reaction tank and scraped off by a scraper, ultimately achieving the purpose of oil-water separation.

[0047] (4) The effluent from flotation tank 3 enters the first pH adjustment tank 5-1, where sulfuric acid solution (1:1) is added to adjust the pH to 2-3. The effluent then enters the Fenton oxidation tank. In Fenton oxidation tank 4, ferrous sulfate at a concentration of 15 g / L and hydrogen peroxide (30%) at a concentration of 15 mL / L are added to initiate the Fenton reaction, generating a large amount of highly oxidizing ·OH, which effectively oxidizes the reducing substances in the water. Testing revealed that the COD concentration of the wastewater after the Fenton reaction was 182 mg / L.

[0048] (5) The effluent from the Fenton oxidation tank 4 enters the second pH adjustment tank 5-2, where sodium hydroxide solution (10%) is added to adjust the pH to 6-9.

[0049] (6) The effluent from the second pH adjustment tank 5-2 enters the MCR membrane tank 6, which is equipped with a hollow fiber ultrafiltration membrane (pore size < 0.1 μm) for mud-water separation. The hollow fiber ultrafiltration membrane removes suspended solids from the water, completing the mud-water separation. During the wastewater treatment process, the flotation tank and the MCR membrane tank produce a large amount of oil flocs and suspended sludge, which are collected and filtered through a screw filter press before being transported for disposal.

[0050] (7) The effluent from the MCR membrane tank 6 enters the adsorption tank 7, where 1 g / L of activated carbon is added to adsorb the reducing substances in the water. Testing shows that the COD concentration of the wastewater after adsorption is 78 mg / L.

[0051] After the treatment in this embodiment, the COD in the fluorescent flaw detection cleaning wastewater is reduced to below 100 mg / L, meeting the first-level emission standard in the "Integrated Wastewater Discharge Standard" (GB8978-1996).

[0052] Example 2

[0053] This embodiment provides a method for treating fluorescent flaw detection cleaning wastewater. The specific steps and setting parameters are consistent with those in Example 1, as follows:

[0054] After the untreated fluorescent flaw detection cleaning wastewater (raw water COD concentration is 8429 mg / L) in the wastewater regulating tank 1 is stabilized, it enters the demulsification reaction tank 2, the flocculation reaction zone and the flotation reaction zone in the flotation tank 3, the flotation tank 3, the first pH adjustment tank 5-1, the Fenton oxidation tank 4, the second pH adjustment tank 5-2, the MCR membrane tank 6, and the adsorption tank 7 in sequence.

[0055] Testing revealed a COD concentration of 1973 mg / L in the wastewater after demulsification. The COD concentration in the wastewater after the Fenton reaction was 136 mg / L. The COD concentration in the wastewater after activated carbon adsorption was 56 mg / L. After treatment using this example, the COD in the fluorescent flaw detection cleaning wastewater dropped below 100 mg / L, meeting the Class I discharge standard in the Integrated Wastewater Discharge Standard (GB8978-1996).

[0056] Example 3

[0057] This embodiment provides a method for treating fluorescent flaw detection cleaning wastewater. The specific steps and setting parameters are consistent with those in Example 1, as follows:

[0058] After the untreated fluorescent flaw detection cleaning wastewater (raw water COD concentration is 9628 mg / L) in the wastewater regulating tank 1 is stabilized, it enters the demulsification reaction tank 2, the flocculation reaction zone and the flotation reaction zone in the flotation tank 3, the flotation tank 3, the first pH adjustment tank 5-1, the Fenton oxidation tank 4, the second pH adjustment tank 5-2, the MCR membrane tank 6, and the adsorption tank 7 in sequence.

[0059] Testing revealed a COD concentration of 2237 mg / L in the wastewater after demulsification. The COD concentration in the wastewater after the Fenton reaction was 142 mg / L. The COD concentration in the wastewater after activated carbon adsorption was 52 mg / L. After treatment using this embodiment, the COD in the fluorescent flaw detection cleaning wastewater dropped below 100 mg / L, meeting the Class I discharge standard in the Integrated Wastewater Discharge Standard (GB8978-1996).

[0060] Example 4

[0061] This embodiment provides a method for treating fluorescent flaw detection cleaning wastewater. The specific steps and setting parameters are consistent with those in Example 1, as follows:

[0062] After the untreated fluorescent flaw detection cleaning wastewater (raw water COD concentration is 10731 mg / L) in the wastewater regulating tank 1 is stabilized, it enters the demulsification reaction tank 2, the flocculation reaction zone and the flotation reaction zone in the flotation tank 3, the flotation tank 3, the first pH adjustment tank 5-1, the Fenton oxidation tank 4, the second pH adjustment tank 5-2, the MCR membrane tank 6, and the adsorption tank 7 in sequence.

[0063] Testing revealed a COD concentration of 2454 mg / L in the wastewater after demulsification. The COD concentration in the wastewater after the Fenton reaction was 166 mg / L. The COD concentration in the wastewater after activated carbon adsorption was 67 mg / L. After treatment using this embodiment, the COD in the fluorescent flaw detection cleaning wastewater dropped below 100 mg / L, meeting the Class I discharge standard in the Integrated Wastewater Discharge Standard (GB8978-1996).

[0064] Comparative Example 1

[0065] The specific steps of the treatment method for fluorescent flaw detection cleaning wastewater provided in this comparative example are as follows:

[0066] (1) After the untreated fluorescent flaw detection cleaning wastewater (raw water COD concentration is 12625 mg / L) in the wastewater regulating tank 1 is stabilized, it enters the demulsification reaction tank 2.

[0067] (2) Demulsification reaction tank 2 was dosed with demulsifier at 0.2 mL / L. In this embodiment, the demulsifier used was Yangjing produced by Anhui Zhonghuan Environmental Protection Technology Co., Ltd. After testing, the COD concentration of the wastewater after demulsification was 6846 mg / L.

[0068] (3) The effluent from the demulsification reaction tank 2 first enters the flocculation reaction zone in the flotation tank 3. Anionic polyacrylamide (flocculant) is added at a concentration of 1‰ at a rate of 4ppm to the flocculation reaction zone. The oil droplets in the wastewater react with the flocculant to form large, low-density oil residue flocs. The wastewater then enters the flotation reaction zone. The flotation reaction zone uses a gas-liquid mixing pump to dissolve air at high pressure. The generated micro-nano bubbles adhere to the oil residue flocs, which are suspended on the surface of the flotation reaction tank and scraped off by a scraper, ultimately achieving the purpose of oil-water separation.

[0069] (4) The effluent from flotation tank 3 enters the first pH adjustment tank 5-1, where sulfuric acid solution (1:1) is added to adjust the pH to 2-3. The effluent then enters the Fenton oxidation tank. In Fenton oxidation tank 4, ferrous sulfate at a concentration of 15 g / L and hydrogen peroxide (30%) at a concentration of 15 mL / L are added to initiate the Fenton reaction, generating a large amount of highly oxidizing ·OH, which effectively oxidizes the reducing substances in the water. Testing revealed that the COD concentration of the wastewater after the Fenton reaction was 585 mg / L.

[0070] (5) The effluent from the Fenton oxidation tank 4 enters the second pH adjustment tank 5-2, where sodium hydroxide solution (10%) is added to adjust the pH to 6-9.

[0071] (6) The effluent from the second pH adjustment tank 5-2 enters the MCR membrane tank 6, which is equipped with a hollow fiber ultrafiltration membrane (pore size < 0.1 μm) for mud-water separation. The hollow fiber ultrafiltration membrane removes suspended solids from the water, completing the mud-water separation. During the wastewater treatment process, the flotation tank and the MCR membrane tank produce a large amount of oil flocs and suspended sludge, which are collected and filtered through a screw filter press before being transported for disposal.

[0072] (7) The effluent from the MCR membrane tank 6 enters the adsorption tank 7, where 1 g / L of activated carbon is added to adsorb the reducing substances in the water. Testing shows that the COD concentration of the wastewater after adsorption is 413 mg / L.

[0073] Comparative Example 2

[0074] The specific steps of the treatment method for fluorescent flaw detection cleaning wastewater provided in this comparative example are as follows:

[0075] (1) After the untreated fluorescent flaw detection cleaning wastewater (raw water COD concentration is 12625 mg / L) in the wastewater regulating tank 1 is stabilized, it enters the demulsification reaction tank 2.

[0076] (2) Demulsifier was added to demulsifier tank 2 at a rate of 1 mL / L. After testing, the COD concentration of the wastewater after demulsification was 2948 mg / L.

[0077] (3) The effluent from the demulsification reaction tank 2 first enters the flocculation reaction zone in the flotation tank 3, where anionic polyacrylamide (flocculant) at a concentration of 1‰ is added at a rate of 4ppm. The wastewater then enters the flotation reaction zone.

[0078] (4) The effluent from flotation tank 3 enters the first pH adjustment tank 5-1, where sulfuric acid solution (1:1) is added to adjust the pH to 2-3. The effluent then enters the Fenton oxidation tank. In Fenton oxidation tank 4, ferrous sulfate at a concentration of 10 g / L and hydrogen peroxide (30%) at a concentration of 10 mL / L are added to initiate the Fenton reaction. Testing reveals that the COD concentration of the wastewater after the Fenton reaction is 314 mg / L.

[0079] (5) The effluent from the Fenton oxidation tank 4 enters the second pH adjustment tank 5-2, where sodium hydroxide solution (10%) is added to adjust the pH to 6-9.

[0080] (6) The effluent from the second pH regulating tank 5-2 enters the MCR membrane tank 6, which is provided with a hollow fiber ultrafiltration membrane (membrane pore size <0.1 μm) for mud-water separation.

[0081] (7) The effluent from the MCR membrane tank 6 enters the adsorption tank 7, where 1 g / L of activated carbon is added to adsorb the reducing substances in the water. Testing shows that the COD concentration of the wastewater after adsorption is 231 mg / L.

[0082] Comparative Example 3

[0083] The specific steps of the treatment method for fluorescent flaw detection cleaning wastewater provided in this comparative example are as follows:

[0084] (1) After the untreated fluorescent flaw detection cleaning wastewater (raw water COD concentration is 12625 mg / L) in the wastewater regulating tank 1 is stabilized, it enters the demulsification reaction tank 2.

[0085] (2) Demulsifier was added to demulsifier tank 2 at a rate of 1 mL / L. After testing, the COD concentration of the wastewater after demulsification was 2948 mg / L.

[0086] (3) The effluent from the demulsification reaction tank 2 first enters the flocculation reaction zone in the flotation tank 3, where anionic polyacrylamide (flocculant) at a concentration of 1‰ is added at a rate of 4ppm. The wastewater then enters the flotation reaction zone.

[0087] (4) The effluent from flotation tank 3 enters the first pH adjustment tank 5-1, where sulfuric acid solution (1:1) is added to adjust the pH to 2-3. The effluent then enters the Fenton oxidation tank. In Fenton oxidation tank 4, ferrous sulfate at a concentration of 15 g / L and hydrogen peroxide (30%) at a concentration of 15 mL / L are added to initiate the Fenton reaction. Testing reveals that the COD concentration of the wastewater after the Fenton reaction is 178 mg / L.

[0088] (5) The effluent from the Fenton oxidation tank 4 enters the second pH adjustment tank 5-2, where sodium hydroxide solution (10%) is added to adjust the pH to 6-9.

[0089] (6) The effluent from the second pH regulating tank 5-2 enters the MCR membrane tank 6, which is provided with a hollow fiber ultrafiltration membrane (membrane pore size <0.1 μm) for mud-water separation.

[0090] (7) The effluent from the MCR membrane tank 6 enters the adsorption tank 7, where 0.5 g / L of activated carbon is added to adsorb the reducing substances in the water. Testing shows that the COD concentration of the wastewater after adsorption is 132 mg / L.

[0091] The COD of the effluents of Comparative Examples 1 to 3 were all higher than 100 mg / L, which did not meet the first-level emission standard in the Integrated Wastewater Discharge Standard (GB8978-1996).

[0092] The embodiment described above is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Persons skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent substitution or equivalent transformation falls within the scope of protection of the present invention.

Claims

1. A method for treating fluorescent flaw detection cleaning wastewater, characterized in that: The wastewater regulating tank (1), demulsification regulating tank (2), flotation tank (3), first pH regulating tank (5-1), Fenton oxidation tank (4), second pH regulating tank (5-2), MCR membrane tank (6) and adsorption tank (7) are connected in sequence. The specific steps are as follows: S1: The fluorescent flaw detection cleaning wastewater to be treated enters the wastewater regulating tank (1) to stabilize the water quality and water volume; S2: The stabilized wastewater enters the demulsification regulating tank (2) where demulsifier is added for demulsification; S3: The wastewater after demulsification enters the flotation tank (3), which includes a flocculation reaction zone and an air flotation reaction zone arranged in sequence; a flocculant is added to the flocculation reaction zone, and the oil droplets in the wastewater are mixed with the flocculant to form oil residue flocs; the oil residue flocs enter the air flotation reaction zone for air flotation treatment, and the oil residue flocs on the surface of the air flotation reaction zone are scraped off to complete oil-water separation; S4: The effluent from the flotation reaction zone of the flotation tank (3) first enters the first pH adjustment tank (5-1) to adjust the pH to 2-3, and then enters the Fenton oxidation tank (4) to perform Fenton reaction; S5: The effluent from the Fenton oxidation tank (4) enters the second pH adjustment tank (5-2) to adjust the pH to 6-9; S6: The effluent from the second pH regulating tank (5-2) enters the MCR membrane tank (6), in which a hollow fiber ultrafiltration membrane is provided; the effluent from the second pH regulating tank (5-2) passes through the hollow fiber ultrafiltration membrane to separate the suspended sludge, and the suspended sludge on the surface is scraped off to complete the mud-water separation; S7: The effluent from the MCR membrane pool (6) enters the adsorption pool (7), and an adsorbent for adsorbing reducing substances is added to the adsorption pool (7); the COD of the wastewater in the adsorption pool (7) drops below the discharge standard, and the wastewater treatment is completed.

2. The method for treating fluorescent flaw detection cleaning wastewater according to claim 1, characterized in that: The amount of the demulsifier added is 1-2 mL / L.

3. The method for treating fluorescent flaw detection cleaning wastewater according to claim 1, characterized in that: The flocculant is anionic polyacrylamide; the concentration of the anionic polyacrylamide is 0.5‰ to 1‰, and the addition amount is 2.5 to 5ppm.

4. The method for treating fluorescent flaw detection cleaning wastewater according to claim 1, characterized in that: A sulfuric acid solution is added into the first pH adjustment tank (5-1) for adjusting the pH value.

5. The method for treating fluorescent flaw detection cleaning wastewater according to claim 1, characterized in that: Ferrous sulfate and hydrogen peroxide solution for performing Fenton reaction are added into the Fenton oxidation tank (4).

6. The method for treating fluorescent flaw detection cleaning wastewater according to claim 5, characterized in that: The concentration of the hydrogen peroxide solution is 25% to 30%, and the added amount is 10 to 18 mL / L; the added amount of ferrous sulfate is 12.3 to 18.4 g / L.

7. The method for treating fluorescent flaw detection cleaning wastewater according to claim 1, characterized in that: The second pH regulating tank (5-2) uses a sodium hydroxide solution with a volume concentration of 10% to regulate pH.

8. The method for treating fluorescent flaw detection cleaning wastewater according to claim 1, characterized in that: The membrane pore size of the hollow fiber ultrafiltration membrane is less than 0.1 μm.

9. The method for treating fluorescent flaw detection cleaning wastewater according to claim 1, characterized in that: The oil residue flocs in the flotation reaction zone of the flotation tank (3) and the suspended sludge in the MCR membrane tank (6) are collected together and then subjected to filter pressing treatment using a screw filter press (8).

10. The method for treating fluorescent flaw detection cleaning wastewater according to claim 1, characterized in that: The adsorbent added to the adsorption tank (7) is activated carbon or adsorption resin; the added amount of the activated carbon is 0.7-1.5 g / L.

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