A method for treating acrylate wastewater

Abstract

The present invention discloses a method for treating acrylate wastewater, comprising: Step 1: adding an initiator to the acrylate wastewater and then carrying out a polymerization reaction; Step 2: adjusting the pH of the wastewater system after the reaction in Step 1 to acidic, performing flocculation precipitation, and pressure filtration; Step 3: adjusting the pH of the wastewater system after pressure filtration in Step 2 to neutral, and introducing it into an ozone oxidation system for ozone oxidation; Step 4: introducing air into the wastewater system after the reaction in Step 3 for air purging, and finally the COD in the effluent reaches the standard for discharging into the sewer. This process is simple, efficient, with low equipment investment and operating costs, effectively solving the problem of treating acrylate wastewater containing antibacterial components and the problem of equipment fouling in the treatment of acrylate wastewater by traditional evaporation processes, and is particularly suitable for treating acrylate wastewater generated in the field of automotive wheels.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a method for treating acrylate wastewater. Background Art

[0002] Acrylates refer to the general term for esters of acrylic acid and its homologues. Due to their self-polymerization or copolymerization characteristics with other monomers, they are important monomers for manufacturing adhesives, synthetic resins, special rubbers, and plastics.

[0003] Automobile wheels are an important part of automobile components. With the growth of the Chinese automobile component industry, the wheel industry has gradually developed and grown. Since wheels are key moving parts of automobiles, their quality is an important guarantee for improving the overall running safety of automobiles. Current automobile wheels are mostly made by stamping and machining. However, at the microscopic level, there will be more or less gaps in the stamped parts. During the high-speed rotation of the wheels, the gaps will tear with the increase in speed and long-term use, thus affecting the running safety of the automobiles. Acrylates are a type of high-efficiency metal adhesive and are commonly used as sealants in the field of automobile wheels. They can fill the wheel gaps by impregnation and polymerize and stably exist under high-temperature conditions, thus making up for the defects of the wheels in this regard.

[0004] When applied to the field of automobile wheels, the quality requirements for acrylates are that they are not easy to polymerize during long-term storage below 40°C, can be quickly dissolved in water without precipitation, and can quickly polymerize and coagulate (the duration is less than 30 s) and do not foam above 90°C. To achieve the above characteristics, they are often applied in this field in the form of a formulation and contain various acrylates, and the inhibitor content is also relatively high.

[0005] Acrylates are organic substances mainly composed of carbon, hydrogen, and oxygen elements and are ideal organic carbon sources for biochemical bacteria. However, since the wheels need to be machined before acrylate treatment, a cutting fluid containing a bacteriostatic agent is required during the machining process. When impregnating with acrylates, the cutting fluid containing the bacteriostatic agent will be mixed with the acrylates, resulting in the final acrylate wastewater containing the bacteriostatic agent. Therefore, directly using biochemical methods to treat acrylate wastewater not only fails to achieve the expected effect but also causes a large number of biochemical bacteria to die.

[0006] Currently, there are many disclosed treatment methods for acrylate wastewater generated in non - automotive wheel hub fields, and most of them adopt biochemical or resource - based treatment methods. For example, CN 114349252 B discloses a comprehensive utilization process method for acrylate washing wastewater. Its process includes steps such as neutralization, activated carbon adsorption, chelating resin adsorption, and electrodialysis separation, and finally recovers methanesulfonic acid and acrylate in the wastewater. This process can comprehensively treat acrylate washing wastewater, effectively separate each component, and achieve the resource recovery of some products, but there are still defects such as a long treatment process, a large amount of wastewater generated during the regeneration of chelating resin resulting in high operating costs, and easy generation of secondary pollution. CN 111253525 B discloses a method for the treatment and resource utilization of (meth) acrylic acid wastewater. Its core is to utilize the easy radical polymerization reaction of acrylate to transform it into a gel product for use as the matrix material for manufacturing water - retaining and water - absorbing materials. This process can effectively treat acrylate in the wastewater and achieve resource utilization. However, whether the treated wastewater can meet the direct discharge or sewer connection standards remains to be verified. CN 110746527 B is similar to CN 111253525 B, with the former using light as an initiator and the latter using a chemical initiator. CN 110724223 B also discloses a resource utilization method for acrylate, which also uses an initiator for radical polymerization reaction to polymerize acrylate in the wastewater for use in the thickener field. There are also patents for resource recovery using the same mechanism, such as CN 110591011 B using special acrylate wastewater to prepare a fixing agent, and CN 110627970 B using pentaerythritol tetraacrylate wastewater to prepare a polyester antistatic agent. CN 105236649 B provides a treatment method mainly based on co - precipitation of CaSO 4 and Al 2 (SO 4 ) 3 supplemented by electrodialysis. This method can reduce the chemical oxygen demand (COD) in the wastewater from 70000 - 150000 mg / L to 2000 - 48000 mg / L, but still does not meet the sewer connection standard of COD less than 500 mg / L specified in the industry.

[0007] Currently, there are not many reports on the treatment of acrylate wastewater generated in the automotive wheel hub field. Adopting biochemical or resource - based treatment methods cannot well solve the acrylate wastewater generated in the automotive wheel hub field. The main reasons are as follows: (1) The acrylate wastewater in the automotive wheel hub field is mixed with cutting fluid containing bactericides, resulting in the difficulty for biochemical bacteria to survive; (2) There are many types of acrylates in this field, with complex compositions and mixed with cutting fluid, making separation difficult and the resource utilization value relatively low; (3) The COD content of the wastewater in this field is high (10000 - 15000 mg / L), and it is difficult for general treatment methods to achieve COD up - to - standard discharge.

[0008] Since the acrylic wastewater generated in the automotive wheel field has the above characteristics, the currently popular acrylic wastewater treatment methods cannot effectively treat it: (1) Electrodialysis: Due to the wide variety of acrylic ester substances in the wastewater, the purity of the recovered acrylic ester is not high and the reuse value is not high; (2) Biochemical method: Due to the presence of bactericides in the wastewater, the biochemical bacteria used are inactivated or even die on a large scale, and the wastewater cannot be effectively treated using biological treatment processes; (3) Evaporation and concentration: Currently, acrylic wastewater generated in the automotive wheel field is mostly treated by evaporation technology, and the evaporated wastewater can also be close to the pipe standard, but the equipment is seriously blocked, and the equipment needs to be heated and cleaned with alkaline water after each evaporation. The operation is cumbersome, the degree of continuity is low, and it will cause secondary pollution. Summary of the invention

[0009] The object of the present invention is to provide a method for treating acrylate wastewater, which is used to effectively treat acrylate wastewater generated in the field of automobile wheels, solve the problems of COD difficult to meet the discharge standards, difficult degradation of pollutants, biological toxicity and easy clogging of equipment in the current conventional process treatment of such wastewater, and at the same time take into account the goal of low treatment cost. The present invention designs a treatment process including steps such as polymerization, precipitation, oxidation and purging, which can effectively solve the problem of difficult treatment of such wastewater. The principle is to first chemically initiate polymerization of acrylate to generate low molecular weight polyacrylate, and then partially hydrolyze it under acidic conditions to generate polyacrylic acid, which can automatically flocculate and precipitate under acidic conditions. After separation and precipitation, the wastewater can reach the nanotube standard of COD less than 500 mg / L after ozone oxidation and air purging. The process is simple, efficient, low in investment and operation costs, has high industrial application value, and is particularly suitable for the treatment of acrylate wastewater containing bactericides.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0011] A method for treating acrylic acid ester wastewater comprises the following steps:

[0012] Step 1: adding an initiator to the acrylate wastewater to carry out a polymerization reaction;

[0013] Step 2: adjusting the pH of the wastewater system after the reaction in step 1 to acidic, flocculating and precipitating, and filtering;

[0014] Step 3: adjusting the pH of the wastewater system after the filter press in step 2 to neutral, and passing it into the ozone oxidation system for ozone oxidation;

[0015] Step 4: introducing air into the wastewater system after the reaction in step 3 for air purge.

[0016] Among them, the acrylate wastewater is acrylate wastewater generated in the field of automobile wheels. This type of wastewater contains various acrylate compounds, and its main components include hydroxyethyl methacrylate, 1,6 - hexanediol dimethacrylate, 2 - hydroxyethylpropyl methacrylate, triethylene glycol dimethacrylate, and ethylene glycol dimethacrylate, etc.; in addition, this type of wastewater also contains a small amount of antibacterial cutting fluid; the total COD content in the wastewater is 10,000 - 15,000 mg / L.

[0017] After the acrylate in the acrylate wastewater is polymerized by an initiator, it can be directly flocculated and precipitated under acidic conditions without using a flocculant, and most of the COD in the wastewater can be removed. The main reason may be that part of the acrylate undergoes hydrolysis to generate polyacrylic acid, and polyacrylic acid has poor water solubility, resulting in self - precipitation phenomenon, and copolymerizes with other unhydrolyzed acrylates with it as the center, thus generating precipitation. After the wastewater is flocculated and precipitated, it is pressure - filtered. The solid is directly treated as solid waste, and the wastewater is oxidized by ozone with a catalyst. The remaining macromolecular organic matter in the wastewater can be oxidized and broken into small molecules, and finally the small molecules are separated from the wastewater by air blowing. After treatment, the COD of the wastewater can be less than 500 mg / L, meeting the sewage treatment plant's standard for discharging into the pipe network. The tail gas generated during the ozone oxidation process and the air blowing process enters the RTO incineration system (regenerative thermal oxidizer) for treatment.

[0018] In step 1, the initiator is any one or a combination of several of benzoyl peroxide, acetyl peroxide, tert - butyl methyl ketone peroxide, and azobisisobutyronitrile.

[0019] In step 1, the addition amount of the initiator is 0.005 - 0.015% of the mass of the acrylate wastewater.

[0020] In step 1, the reaction temperature of the polymerization reaction is 15 - 50 °C, and the reaction time is 1 - 48 h.

[0021] In step 2, an inorganic acid is added to the wastewater system after the reaction in step 1 to adjust the pH to acidic. Preferably, the pH is adjusted to 1 - 3; the inorganic acid is any one or a combination of two of dilute sulfuric acid and dilute hydrochloric acid.

[0022] In step 2, the pressure - filtration is to perform solid - liquid separation using a conventional plate - and - frame filter press.

[0023] In step 3, liquid alkali (sodium hydroxide solution) is added to the wastewater system after pressure - filtration in step 2 to adjust the pH to neutral. Preferably, the pH is adjusted to 6.5 - 7.5.

[0024] In step 3, before adjusting the pH to neutral, the wastewater system is restored to room temperature.

[0025] In Step 3, the ozone oxidation system consists of ozone gas and an ozone catalyst.

[0026] Among them, the ozone concentration of the ozone gas is 80 - 150 mg / L, and the average bubble size of the ozone gas is 100 - 500 μm; the ozone catalyst is a commercially available conventional ozone catalyst, and its active components include any two or three of cerium oxide, platinum oxide, manganese oxide, and palladium oxide, and its carrier includes any one or two of aluminum trioxide and titanium dioxide.

[0027] In Step 3, the gas-liquid ratio of the ozone oxidation is 3 - 10:1, the oxidation temperature of the ozone oxidation is 20 - 40 °C, and the oxidation time is 0.5 - 2 h.

[0028] In Step 4, the average bubble size of the gas for air purging is 0.5 - 1 mm; the gas-liquid ratio of the air purging is 10 - 20:1, and the purging time is 5 - 15 min.

[0029] A method for treating acrylate wastewater provided by the present invention is mainly applied to acrylate wastewater generated in the field of automotive wheels. This type of wastewater contains a variety of acrylate mixtures. After polymerization by an initiator in the wastewater, it can be dissolved under alkaline conditions and can automatically flocculate and precipitate under acidic conditions. Therefore, under acidic conditions, without adding a flocculant, most of the COD in the wastewater can be removed through flocculation and precipitation. Since the automotive wheels need to be cut before acrylate impregnation, the cutting fluid used in the process contains antibacterial components, which are biotoxic to the microorganisms in the biological treatment process, resulting in the inability to use low-cost biochemical treatment methods to treat such wastewater. Therefore, the present invention adopts an ozone oxidation process to first oxidize the acrylate polymer macromolecules into small molecules, and then separates the small molecule organic matter from the wastewater by air purging, so that the wastewater meets the standard for discharging into the sewer (the standard for discharging into the sewer of the sewage treatment station is COD ≤ 500 mg / L). Figure 1 It is a schematic diagram of the steps of the method for treating acrylate wastewater proposed by the present invention.

[0030] Beneficial effects:

[0031] 1. The present invention can effectively solve the problem of treating acrylate wastewater containing antibacterial components, and has a low operating cost;

[0032] 2. The present invention can solve the problem of equipment fouling when treating acrylate wastewater by traditional evaporation processes, and has a high degree of continuity and strong reliability. Description of the drawings

[0033] The following further specifically describes the present invention in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0034] Figure 1 Schematic diagram of the steps of the method for treating acrylate wastewater proposed by the present invention.

[0035] Figure 2 Comparison diagram before and after treating the dirt formed in the rotary bottle after treating acrylate wastewater by the evaporation process in Comparative Example 7. Specific embodiments

[0036] The present invention will be further described according to the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and do not limit the present invention.

[0037] The wastewater treated in the following examples is all conventional acrylate wastewater generated in the field of automobile wheels. The main components include 2-hydroxyethyl methacrylate, 1,6-hexanediol dimethacrylate, 2-hydroxyethylpropyl methacrylate, triethylene glycol dimethacrylate, and ethylene glycol dimethacrylate, etc. In addition, a small amount of antibacterial cutting fluid is also contained in this kind of wastewater. The total COD content in the wastewater is 10,000 - 15,000 mg / L.

[0038] The materials and reagents used in the following examples are all commercially available conventional reagents and can be obtained from commercial channels.

[0039] Example 1

[0040] Treat 1000 mL of acrylate wastewater containing 11050 mg / L COD by the acrylate wastewater treatment method provided by the present invention. The specific steps are as follows:

[0041] Step 1: Add 0.05 g of initiator benzoyl peroxide to 1000 mL of acrylate wastewater (COD concentration is 11050 mg / L), and react at 15°C for 48 h;

[0042] Step 2: Raise the temperature of the wastewater treated in Step 1 to room temperature, add dilute sulfuric acid, adjust the pH = 1, perform flocculation precipitation and then pressure filtration. The solid is treated as solid waste, and the wastewater (COD concentration is 2736 mg / L) enters Step 3 for treatment;

[0043] Step 3: Adjust the pH of the wastewater treated in Step 2 to neutral with liquid caustic soda, and then introduce it into the ozone oxidation system for ozone oxidation. Select an ozone catalyst with alumina as the carrier and cerium oxide, platinum oxide, and palladium oxide as the active components (purchased from Pingxiang Rongjian Environmental Protection Chemical Packing Co., Ltd., model LC01L2); the ozone concentration is 80 mg / L, the average size of ozone bubbles is 100 μm, the gas-liquid ratio is 10:1, the oxidation temperature is 20°C, and the oxidation time is 1 h. The treated wastewater (COD concentration is 2009 mg / L) enters Step 4 for treatment;

[0044] Step 4: Introduce air into the wastewater treated in Step 3. The average size of the bubbles is 0.5 mm, the gas-liquid ratio is 15:1, and the purging time is 10 min. After purging, the COD of the wastewater is 278 mg / L, meeting the standard for discharging into the sewer network.

[0045] Example 2

[0046] Use the acrylate wastewater treatment method provided by the present invention to treat 1500 mL of acrylate wastewater containing 13720 mg / L of COD. The specific steps are as follows:

[0047] Step 1: Add 0.22 g of initiator acetyl peroxide to 1500 mL of acrylate wastewater (COD concentration is 13720 mg / L), and react at 25 °C for 17 h.

[0048] Step 2: Keep the temperature of the wastewater treated in Step 1 at room temperature, add dilute hydrochloric acid to adjust the pH = 2.5, perform flocculation precipitation and then pressure filtration. The solid is treated as solid waste, and the wastewater (COD concentration is 2953 mg / L) enters Step 3 for treatment.

[0049] Step 3: Adjust the pH of the wastewater treated in Step 2 to neutral with liquid caustic soda, and then introduce it into the ozone oxidation system for ozone oxidation. Select an ozone catalyst with aluminum oxide as the carrier and cerium oxide, manganese oxide, and palladium oxide as the active components (purchased from Pingxiang Rongjian Environmental Protection Chemical Packing Co., Ltd., model LC01L3); the ozone concentration is 132 mg / L, the average size of the ozone bubbles is 325 μm, the gas-liquid ratio is 6:1, the oxidation temperature is 25 °C, and the oxidation time is 0.5 h. After treatment, the wastewater (COD concentration is 1983 mg / L) enters Step 4 for treatment.

[0050] Step 4: Introduce air into the wastewater treated in Step 3. The average size of the bubbles is 0.7 mm, the gas-liquid ratio is 13:1, and the purging time is 8 min. After purging, the COD of the wastewater is 327 mg / L, meeting the standard for discharging into the sewer network.

[0051] Example 3

[0052] Use the acrylate wastewater treatment method provided by the present invention to treat 2000 mL of acrylate wastewater containing 14300 mg / L of COD. The specific steps are as follows:

[0053] Step 1: Add 0.10 g of initiator tert-butyl peroxide to 2000 mL of acrylate wastewater (COD concentration is 14300 mg / L), and react at 30 °C for 24 h.

[0054] Step 2: Cool the wastewater treated in Step 1 to room temperature, add dilute sulfuric acid, adjust the pH to 3, perform flocculation precipitation and then pressure filtration. The solid is treated as solid waste, and the wastewater (with a COD concentration of 3177 mg / L) enters Step 3 for treatment;

[0055] Step 3: Adjust the pH of the wastewater treated in Step 2 to neutral with liquid caustic soda, and then introduce it into the ozone oxidation system for ozone oxidation. Select an ozone catalyst with a carrier of titanium dioxide and active components of cerium oxide, platinum oxide, and manganese oxide (purchased from Pingxiang Rongjian Environmental Protection Chemical Packing Co., Ltd., model LC02LI1); the ozone concentration is 150 mg / L, the average size of ozone bubbles is 500 μm, the gas-liquid ratio is 3:1, the oxidation temperature is 25 °C, and the oxidation time is 2 h. After the treatment, the wastewater (with a COD concentration of 1825 mg / L) enters Step 4 for treatment;

[0056] Step 4: Pass air into the wastewater treated in Step 3, with an average bubble size of 1 mm, a gas-liquid ratio of 20:1, and a purging time of 5 min; after purging, the COD of the wastewater is 134 mg / L, meeting the standards for discharging into the sewer.

[0057] Example 4

[0058] Use the acrylate wastewater treatment method provided by the present invention to treat 1000 mL of acrylate wastewater containing 15000 mg / L COD. The specific steps are as follows:

[0059] Step 1: Add 0.15 g of initiator azobisisobutyronitrile to 1000 mL of acrylate wastewater (with a COD concentration of 15000 mg / L) and react at 50 °C for 1 h;

[0060] Step 2: Cool the wastewater treated in Step 1 to room temperature, add dilute hydrochloric acid, adjust the pH to 3, perform flocculation precipitation and then pressure filtration. The solid is treated as solid waste, and the wastewater (with a COD concentration of 3109 mg / L) enters Step 3 for treatment;

[0061] Step 3: Adjust the pH of the wastewater treated in Step 2 to neutral with liquid caustic soda, and then introduce it into the ozone oxidation system for ozone oxidation. Select an ozone catalyst with a carrier of aluminum oxide and active components of cerium oxide and palladium oxide (purchased from Beijing Shanmei Shuimei Environmental Protection High-Tech Co., Ltd., model SM120); the ozone concentration is 100 mg / L, the average size of ozone bubbles is 350 μm, the gas-liquid ratio is 9:1, the oxidation temperature is 25 °C, and the oxidation time is 2 h. After the treatment, the wastewater (with a COD concentration of 2145 mg / L) enters Step 4 for treatment;

[0062] Step 4: Pass air into the wastewater treated in Step 3, with an average bubble size of 0.9 mm, a gas-liquid ratio of 13:1, and a purging time of 15 min; after purging, the COD of the wastewater is 421 mg / L, meeting the sewer discharge standard.

[0063] Example 5

[0064] Treat 1000 mL of acrylate wastewater containing 123000 mg / L COD by using the acrylate wastewater treatment method provided by the present invention. The specific steps are as follows:

[0065] Step 1: Add a mixed initiator of 0.05 g of benzoyl peroxide and 0.05 g of azobisisobutyronitrile to 1000 mL of acrylate wastewater (COD concentration of 12300 mg / L), and react at 45 °C for 5 h;

[0066] Step 2: Cool the temperature of the wastewater treated in Step 1 to room temperature, add dilute sulfuric acid, adjust the pH to 1.8, perform flocculation precipitation and then pressure filtration, treat the solid as solid waste, and the wastewater (COD concentration of 2252 mg / L) enters Step 3 for treatment;

[0067] Step 3: Adjust the pH of the wastewater treated in Step 2 to neutral with liquid caustic soda, and then pass it into the ozone oxidation system for ozone oxidation. Select an ozone catalyst with titanium dioxide as the carrier and manganese oxide, platinum oxide, and palladium oxide as the active components (purchased from Beijing Shanmei Shuimei Environmental Protection High-Tech Co., Ltd., model SM740); the ozone concentration is 143 mg / L, the average size of ozone bubbles is 380 μm, the gas-liquid ratio is 6.5:1, the oxidation temperature is 35 °C, and the oxidation time is 0.8 h. After treatment, the wastewater (COD concentration of 1873 mg / L) enters Step 4 for treatment;

[0068] Step 4: Pass air into the wastewater treated in Step 3, with an average bubble size of 0.9 mm, a gas-liquid ratio of 18:1, and a purging time of 7 min; after purging, the COD of the wastewater is 332 mg / L, meeting the sewer discharge standard.

[0069] Example 6

[0070] Treat 1000 mL of acrylate wastewater containing 11890 mg / L COD by using the acrylate wastewater treatment method provided by the present invention. The specific steps are as follows:

[0071] Step 1: Add a mixed initiator of 0.07 g of acetyl peroxide and 0.06 g of tert-butyl hydroperoxide to 1000 mL of acrylate wastewater (COD concentration of 11890 mg / L), and react at 40 °C for 2 h;

[0072] Step 2: Cool the wastewater treated in Step 1 to room temperature, add dilute sulfuric acid, adjust the pH to 2, perform flocculation precipitation and then pressure filtration. The solid is treated as solid waste, and the wastewater (with a COD concentration of 2103 mg / L) enters Step 3 for treatment;

[0073] Step 3: Adjust the pH of the wastewater treated in Step 2 to neutral with liquid caustic soda, and then introduce it into the ozone oxidation system for ozone oxidation. Select an ozone catalyst with alumina as the carrier and cerium oxide, palladium oxide, and manganese oxide as the active components (purchased from Beijing Shanmei Shuimei Environmental Protection High-Tech Co., Ltd., model SM425); the ozone concentration is 98 mg / L, the average size of ozone bubbles is 150 μm, the gas-liquid ratio is 7.5:1, the oxidation temperature is 35 °C, and the oxidation time is 1.5 h. After the treatment is completed, the wastewater (with a COD concentration of 1873 mg / L) enters Step 4 for treatment;

[0074] Step 4: Pass air into the wastewater treated in Step 3. The average size of the bubbles is 0.7 mm, the gas-liquid ratio is 11.5:1, and the purging time is 15 min; after the purging is completed, the COD of the wastewater is 134 mg / L, reaching the standard for discharging into the sewer.

[0075] Example 7

[0076] Use the acrylate wastewater treatment method provided by the present invention to treat 1500 mL of acrylate wastewater containing 12570 mg / L of COD. The specific steps are as follows:

[0077] Step 1: Add a mixed initiator of 0.04 g of acetyl peroxide and 0.12 g of azobisisobutyronitrile to 1500 mL of acrylate wastewater (with a COD concentration of 12570 mg / L), and react at 50 °C for 1 h;

[0078] Step 2: Cool the wastewater treated in Step 1 to room temperature, add dilute hydrochloric acid, adjust the pH to 2.8, perform flocculation precipitation and then pressure filtration. The solid is treated as solid waste, and the wastewater (with a COD concentration of 2334 mg / L) enters Step 3 for treatment;

[0079] Step 3: Adjust the pH of the wastewater treated in Step 2 to neutral with liquid caustic soda, and then introduce it into the ozone oxidation system for ozone oxidation. Select an ozone catalyst with titanium dioxide as the carrier and cerium oxide and palladium oxide as the active components (purchased from Heraeus Precious Metals Technology (China) Co., Ltd., model K-0290); the ozone concentration is 119 mg / L, the average size of ozone bubbles is 350 μm, the gas-liquid ratio is 4:1, the oxidation temperature is 30 °C, and the oxidation time is 1.5 h. After the treatment is completed, the wastewater (with a COD concentration of 1937 mg / L) enters Step 4 for treatment;

[0080] Step 4: Introduce air into the wastewater treated in Step 3. The average size of the bubbles is 0.8 mm, the gas-liquid ratio is 19:1, and the purging time is 6 min. After purging, the COD of the wastewater is 392 mg / L, meeting the standard for discharging into the sewer network.

[0081] Comparative Example 1

[0082] Treat 1000 mL of acrylate wastewater containing 11050 mg / L COD (the same acrylate wastewater treated in Example 1) by first flocculating and then evaporating, and compare the treatment effects with those of Example 1. The specific steps are as follows:

[0083] Step 1: Add 0.05 g of benzoyl peroxide (BPO) to 1000 mL of acrylate wastewater (COD concentration is 11050 mg / L), and react at 15°C for 48 h;

[0084] Step 2: Raise the temperature of the wastewater treated in Step 1 to room temperature, add dilute sulfuric acid, adjust the pH to 1, perform flocculation precipitation and then pressure filtration. The solid is treated as solid waste, and the wastewater (COD concentration is 2736 mg / L) enters Step 3 for treatment;

[0085] Step 3: Evaporate the wastewater treated in Step 2 to dryness under a vacuum condition of 80°C and -0.09 MPa, collect the condensed water, and detect its COD value to be 454 mg / L. After evaporation and concentration, scaling occurs in the equipment, but the scale formed can be dissolved under alkaline conditions. See the following Figure 2 , Figure 2 In the following, Figure a shows the scaled rotary bottle, Figure b shows the scaled rotary bottle with liquid caustic added, and Figure c shows the rotary bottle after scale removal by liquid caustic (to make the comparison of the rotary bottle before and after scale removal obvious, only the scale in the area impregnated by the liquid level in the rotary bottle is removed).

[0086] It can be seen from the results that after flocculation precipitation, although the effluent can meet the standard for discharging into the sewer network by evaporation, there are still two defects: one is that the COD content in the wastewater is higher than that in Example 1 and there is a risk of exceeding the standard; the other is that the equipment is prone to scaling after evaporation. Although the scale can be cleaned with liquid caustic, it is easy to produce secondary high-salt wastewater pollution.

[0087] In summary, by using the acrylate wastewater treatment method provided by the present invention, the COD content in the acrylate wastewater can be effectively reduced, the problem of equipment scaling caused by the traditional evaporation process can be solved, and the stable discharge of the wastewater up to the standard into the sewer network can be achieved.

[0088] The present invention provides an idea and method for treating acrylate wastewater. There are many methods and ways to specifically implement this technical solution. The above description is only a preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented by existing technologies.

Claims

1. A method for treating acrylic acid ester wastewater, characterized in that: The following steps are involved: Step 1: adding an initiator to the acrylate wastewater to carry out a polymerization reaction; Step 2: adjusting the pH of the wastewater system after the reaction in step 1 to 3, flocculating and precipitating, and filtering; Step 3: After the wastewater system after the pressure filtration in step 2 is restored to room temperature, the pH is adjusted to neutral, and then introduced into the ozone oxidation system for ozone oxidation; Step 4: introducing air into the wastewater system after the reaction in step 3 for air purge; The acrylic acid ester wastewater is acrylic acid ester wastewater generated in the field of automobile wheel hubs; In step 1, the initiator is tert-butyl ketone peroxide; the amount of the initiator added is 0.005% of the mass of the acrylate wastewater; the reaction temperature of the polymerization reaction is 30° C., and the reaction time is 24 hours; In step 3, the ozone oxidation system is composed of ozone gas and an ozone catalyst; the ozone catalyst has active ingredients of cerium oxide, platinum oxide and manganese oxide, and its carrier is titanium dioxide; the ozone concentration of the ozone gas is 150 mg / L, and the average bubble size of the ozone gas is 500 μm; the gas-liquid volume ratio of the ozone oxidation is 3:1, the oxidation temperature of the ozone oxidation is 25° C., and the oxidation time is 2 hours; In step 4, the average bubble size of the air purging gas is 1 mm; the gas-liquid volume ratio of the air purging is 20:1, and the purging time is 5 minutes.

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