Demulsifier for treating waste emulsion and demulsification process thereof

Abstract

The invention relates to the technical field of demulsifiers, and particularly discloses a demulsifier for treating waste emulsion and a demulsification process of the demulsifier. The invention discloses a demulsifying agent for treating waste emulsion. The demulsifying agent is prepared from the following raw material components in parts by weight: 1 to 1.2 parts of calcium chloride, 1 to 1.1 parts of polyaluminum chloride, 0.7 to 0.85 part of anionic polyacrylamide, 0.3 to 0.5 part of ferrous sulfate, 1 to 1.2 parts of a surfactant, 0.4 to 0.5 part of an auxiliary demulsifying agent, 0.1 to 0.2 part of a synergist and 0.1 to 0.2 part of a stabilizer. The demulsifier disclosed by the invention has a relatively good demulsification effect, so that the treatment effect on the waste emulsion is improved.

Description

Technical Field

[0001] The present application relates to the technical field of demulsifiers, and in particular to a demulsifier for treating waste emulsions and a demulsification process thereof. Background Art

[0002] Waste emulsion generally refers to the emulsion that has become ineffective after use in the metal processing process. Emulsion is a mixture of water, base oil, emulsifier, rust inhibitor, preservative, defoamer and other additives, which is used for cooling, lubrication, cleaning and rust prevention in the metal processing process. Waste emulsion needs to be purified or recovered by physical, chemical or biological methods to reduce the impact on the environment. In some cases, waste emulsion may need to be professionally treated to comply with local environmental regulations and standards. The commonly used treatment method is to use demulsifiers for demulsification, but the demulsification effect of commonly used demulsifiers is not good, which affects the treatment effect of waste emulsion. Summary of the invention

[0003] In order to improve the treatment effect of waste emulsion, the present application provides a demulsifier and a demulsification process for treating waste emulsion.

[0004] In the first aspect, the present application provides a demulsifier for treating waste emulsion, which adopts the following technical solution: A demulsifier for treating waste emulsion, wherein the raw materials of the demulsifier include the following components in parts by weight: 1-1.2 parts of calcium chloride, 1-1.1 parts of polyaluminium chloride, 0.7-0.85 parts of anionic polyacrylamide, 0.3-0.5 parts of ferrous sulfate, 1-1.2 parts of surfactant, 0.4-0.5 parts of demulsifier, 0.1-0.2 parts of synergist and 0.1-0.2 parts of stabilizer.

[0005] By adopting the above technical scheme, calcium chloride, polyaluminium chloride, anionic polyacrylamide and ferrous ammonium sulfate are used in combination to achieve a good demulsification effect; the surfactant first promotes the initial destruction of the emulsified structure of the oil-water mixture by reducing the interfacial tension, and then the demulsifier further strengthens the destruction process, and then the synergist interacts with the oil droplets to promote the coagulation of the oil droplets, and finally the stabilizer forms a protective layer on its surface to prevent the oil droplets from emulsifying again. This series of processes together ensures the high efficiency of the demulsifier in treating the waste emulsion. Therefore, the demulsifier in the present application is used to demulsify the waste emulsion, thereby improving the treatment effect of the waste emulsion.

[0006] In a specific embodiment, the surfactant includes one or more of polyoxyethylene alkyl ether, fatty alcohol polyoxyethylene ether, and alkylphenol polyoxyethylene ether.

[0007] By adopting the above technical scheme, polyoxyethylene alkyl ether, fatty alcohol polyoxyethylene ether and alkylphenol polyoxyethylene ether have good fluidity, are easy to disperse quickly in the oil-water system, easily form a stable interfacial film, reduce the oil-water interfacial tension, and thus promote oil-water separation.

[0008] In a specific embodiment, the demulsifier comprises a mixture of polyacrylate and polymethacrylate.

[0009] By adopting the above technical solution, the molecular structure of polyacrylate enables it to form chemical bonds with water molecules and oil molecules in the demulsification process, further destroying the emulsified structure. Polymethacrylate is in powder or gel form and is easy to be evenly dispersed in the mixture during stirring. It works synergistically with polyacrylate to cause the oil droplets in the emulsion to agglomerate, thereby improving the demulsification efficiency and effect.

[0010] In a specific embodiment, the synergist includes a mixture of fatty alcohol and sodium sulfate.

[0011] By adopting the above technical scheme, fatty alcohol, as a surface-active compound, can adhere to the surface of oil droplets, change the surface properties of oil droplets, thereby reducing the repulsion between oil droplets and promoting oil droplet coagulation; the anions contained in sodium sulfate can interact with the ions on the surface of oil droplets, weaken the electrostatic repulsion between oil droplets, and the presence of sodium sulfate can increase the ionic strength in the solution. Therefore, the combination of fatty alcohol and sodium sulfate can further improve the demulsification effect.

[0012] In a specific embodiment, the stabilizer includes glyceryl monostearate.

[0013] By adopting the above technical solution, glyceryl monostearate can maintain the stability of the demulsifier and the sustainability of the demulsification effect; glyceryl monostearate exists in the form of powder and is easy to mix evenly with surfactants, demulsifiers and other ingredients. The molecular structure of this substance contains stearic acid chains, which can form a stable film layer with the surface of oil droplets during the demulsification process, prevent the emulsion from re-emulsification, and maintain the existing demulsification effect.

[0014] In a specific embodiment, the preparation of the demulsifier comprises the following steps: First, the surfactant, demulsifier, synergist and stabilizer are stirred at 55-65° C. for 30-60 minutes, and the solvent is added during the stirring process to obtain a mixed liquid. Then calcium chloride, polyaluminum chloride, anionic polyacrylamide and ferrous sulfate are added and stirred to mix evenly to obtain a demulsifier.

[0015] By adopting the above technical scheme, the surfactant, demulsifier, synergist and stabilizer are stirred for a specified time under specific temperature conditions, thereby achieving effective preparation of the demulsifier and ensuring the performance stability and efficient demulsification effect of the composite demulsifier; the addition of solvent and stirring can effectively improve the solubility and uniformity of the raw materials in the preparation process, thereby improving the performance and stability of the composite demulsifier.

[0016] In the second aspect, the present application provides a demulsification process, which adopts the following technical solution: A demulsification process comprises the following steps: Oil separation and demulsification: adding the waste emulsified liquid into the oil separation regulating tank, letting it stand, extracting the mixed liquid at the lower layer and entering the demulsification reaction tank A containing the demulsifier for demulsification, and obtaining the treated liquid A after demulsification; Flocculation and precipitation: the treated liquid A is first passed into the demulsification reaction tank B with coagulant PAC, and then passed into the demulsification reaction tank C with flocculant PAM for flocculation and precipitation to obtain the treated liquid B; Adjusting pH: passing the treated liquid B into the demulsification reaction tank D, adding alkali to adjust the pH to 6-9, and obtaining the treated liquid C; Sedimentation: Pass the treated liquid C into the sedimentation tank, let it settle, filter to remove the mud, and flotate the oil-water mixture to obtain the treated liquid D to complete the demulsification.

[0017] By adopting the above technical scheme, the waste emulsion is first added to the oil separation regulating tank, and allowed to stand to roughly isolate a part of the oil to ensure the subsequent demulsification efficiency; then added to the demulsification reaction tank A for demulsification, the demulsifier can destroy the balance of water and oil, reduce the interfacial tension, so that the water and oil are separated, the oil is gathered in the upper layer, and the water is located in the lower layer; then the upper oil layer is first introduced into the demulsification reaction tank B with the coagulant PAC, and then introduced into the demulsification reaction tank C with the flocculant PAM, PAC and PAM have the effects of adsorption bridging and sediment trapping, so that the sediment is precipitated to the lower layer, and then the obtained treated liquid B is adjusted to pH=6-9 by adding alkali to maintain certain living conditions for the growth of bacteria in the mixed liquid, and at the same time has the effect of flocculation, so as to prepare for the subsequent biochemical reaction, and finally the treated liquid C is introduced into the sedimentation tank, allowed to stand and settle, filtered to remove the mud residue, and the oil-water mixed liquid is subjected to flotation reaction to obtain the treated liquid D, and the demulsification is completed.

[0018] In a specific embodiment, in the oil separation and demulsification step, the weight ratio of the demulsifier to the waste emulsion is (25-65):1000.

[0019] By adopting the above technical solution, the addition amount of the demulsifier is further limited, so that the demulsification effect of the waste emulsion can be further improved.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. The present application uses calcium chloride, polyaluminium chloride, anionic polyacrylamide and ferrous sulfate to achieve a good demulsification effect; the surfactant first promotes the initial destruction of the emulsified structure of the oil-water mixture by reducing the interfacial tension, and then the demulsifier further strengthens the destruction process, and then the synergist interacts with the oil droplets to promote the coagulation of the oil droplets, and finally the stabilizer forms a protective layer on its surface to prevent the oil droplets from emulsifying again. This series of processes jointly ensures the high efficiency of the demulsifier in treating the waste emulsion, so the demulsifier in the present application is used to demulsify the waste emulsion, thereby improving the treatment effect of the waste emulsion; 2. The molecular structure of the polyacrylate in the present application enables it to form chemical bonds with water molecules and oil molecules in the demulsification process, further destroying the emulsified structure. The polymethacrylate is in the form of powder or gel, which is easy to be evenly dispersed in the mixture during stirring. It works synergistically with the polyacrylate to agglomerate the oil droplets in the emulsion, thereby improving the demulsification efficiency and effect. 3. The process in the present application first adds the waste emulsion into the oil separation regulating tank, allows it to stand, and roughly isolates a part of the oil to ensure the subsequent demulsification efficiency; then adds it into the demulsification reaction tank A for demulsification, the demulsifier can destroy the water-oil balance, reduce the interfacial tension, separate the water and oil, the oil gathers in the upper layer, and the water is located in the lower layer; then the upper oil layer is first passed into the demulsification reaction tank B with the coagulant PAC, and then passed into the demulsification reaction tank C with the flocculant PAM, PAC and PAM have the effects of adsorption bridging and sediment trapping, so that the sediment is precipitated to the lower layer, and then the obtained treated liquid B is adjusted to pH = 6-9 by adding alkali to maintain certain living conditions for the growth of bacteria in the mixed liquid, and at the same time has the effect of flocculation, preparing for the subsequent biochemical reaction, and finally passing the treated liquid C into the sedimentation tank, allowing it to stand and settle, filtering to remove the mud residue, and flotating the oil-water mixture to obtain the treated liquid D, and the demulsification is completed. DETAILED DESCRIPTION

[0021] The present application is further described in detail below with reference to the embodiments.

[0022] All raw materials in the examples can be obtained commercially. Surfactants include but are not limited to a mixture of one or more of polyoxyethylene alkyl ethers, fatty alcohol polyoxyethylene ethers, and alkylphenol polyoxyethylene ethers, and polyoxyethylene alkyl ethers are preferred in this application; fatty alcohols include but are not limited to a mixture of one or more of lauryl alcohol, octanol, tetradecanol, and hexadecanol, and lauryl alcohol is preferred in this application. Example

[0023] Example 1 Embodiment 1 provides a method for preparing a demulsifier, comprising the following steps: First, 1kg of surfactant, 0.4kg of demulsifier, 0.1kg of synergist and 0.1kg of stabilizer are stirred at 55°C for 60min, and a solvent is added during the stirring process to dissolve the raw materials to obtain a mixed liquid, and then 1kg of calcium chloride, 1kg of polyaluminium chloride, 0.7kg of anionic polyacrylamide and 0.3kg of ferrous sulfate are added and stirred to mix evenly to obtain a demulsifier; wherein the surfactant is polyoxyethylene alkyl ether; the demulsifier is a mixture of polyacrylate and polymethacrylate, and the weight ratio of polyacrylate to polymethacrylate is 1:1; the synergist is a mixture of fatty alcohol and sodium sulfate, and the weight ratio of fatty alcohol to sodium sulfate is 1:1, and the fatty alcohol is lauryl alcohol; the stabilizer is glyceryl monostearate; and the solvent is ethanol.

[0024] Example 2 Embodiment 2 provides a method for preparing a demulsifier, comprising the following steps: First, 1.1 kg of surfactant, 0.45 kg of demulsifier, 0.15 kg of synergist and 0.15 kg of stabilizer are stirred at 55 ° C for 60 minutes, and a solvent is added during the stirring process to dissolve the raw materials to obtain a mixed liquid, and then 1.1 kg of calcium chloride, 1.05 kg of polyaluminum chloride, 0.78 kg of anionic polyacrylamide and 0.4 kg of ferrous sulfate are added, and the mixture is stirred and mixed evenly to obtain a demulsifier; wherein the surfactant is a polyoxyethylene alkyl ether; the demulsifier is a mixture of polyacrylate and polymethacrylate, and the weight ratio of polyacrylate to polymethacrylate is 1:1; the synergist is a mixture of fatty alcohol and sodium sulfate, and the weight ratio of fatty alcohol to sodium sulfate is 1:1, and the fatty alcohol is lauryl alcohol; the stabilizer is glyceryl monostearate; and the solvent is ethanol.

[0025] Example 3 Embodiment 3 provides a method for preparing a demulsifier, comprising the following steps: First, 1.2kg of surfactant, 0.5kg of demulsifier, 0.2kg of synergist and 0.2kg of stabilizer are stirred at 55°C for 60min, and a solvent is added during the stirring process to dissolve the raw materials to obtain a mixed liquid, and then 1.2kg of calcium chloride, 1.1kg of polyaluminium chloride, 0.85kg of anionic polyacrylamide and 0.5kg of ferrous sulfate are added and stirred to mix evenly to obtain a demulsifier; wherein the surfactant is polyoxyethylene alkyl ether; the demulsifier is a mixture of polyacrylate and polymethacrylate, and the weight ratio of polyacrylate to polymethacrylate is 1:1; the synergist is a mixture of fatty alcohol and sodium sulfate, and the weight ratio of fatty alcohol to sodium sulfate is 1:1, and the fatty alcohol is lauryl alcohol; the stabilizer is glyceryl monostearate; and the solvent is ethanol.

[0026] Example 4 Embodiment 4 provides a method for preparing a demulsifier, comprising the following steps: First, 1.1 kg of surfactant, 0.45 kg of demulsifier, 0.15 kg of synergist and 0.15 kg of stabilizer are stirred at 60 ° C for 45 minutes, and a solvent is added during the stirring process to dissolve the raw materials to obtain a mixed liquid, and then 1.1 kg of calcium chloride, 1.05 kg of polyaluminum chloride, 0.78 kg of anionic polyacrylamide and 0.4 kg of ferrous sulfate are added, and the mixture is stirred and mixed evenly to obtain a demulsifier; wherein the surfactant is polyoxyethylene alkyl ether; the demulsifier is a mixture of polyacrylate and polymethacrylate, and the weight ratio of polyacrylate to polymethacrylate is 1:1; the synergist is a mixture of fatty alcohol and sodium sulfate, and the weight ratio of fatty alcohol to sodium sulfate is 1:1, and the fatty alcohol is lauryl alcohol; the stabilizer is glyceryl monostearate; and the solvent is ethanol.

[0027] Example 5 Embodiment 5 provides a method for preparing a demulsifier, comprising the following steps: First, 1.1 kg of surfactant, 0.45 kg of demulsifier, 0.15 kg of synergist and 0.15 kg of stabilizer are stirred at 65 ° C for 30 minutes, and a solvent is added during the stirring process to dissolve the raw materials to obtain a mixed liquid, and then 1.1 kg of calcium chloride, 1.05 kg of polyaluminum chloride, 0.78 kg of anionic polyacrylamide and 0.4 kg of ferrous sulfate are added, and the mixture is stirred and mixed evenly to obtain a demulsifier; wherein the surfactant is polyoxyethylene alkyl ether; the demulsifier is a mixture of polyacrylate and polymethacrylate, and the weight ratio of polyacrylate to polymethacrylate is 1:1; the synergist is a mixture of fatty alcohol and sodium sulfate, and the weight ratio of fatty alcohol to sodium sulfate is 1:1, and the fatty alcohol is lauryl alcohol; the stabilizer is glyceryl monostearate; and the solvent is ethanol.

[0028] Example 6 The difference between Example 6 and Example 4 is that the demulsifier is polyacrylate; the remaining steps are consistent with Example 4.

[0029] Example 7 The difference between Example 7 and Example 4 is that the demulsifier is polymethacrylate; the remaining steps are consistent with Example 4.

[0030] Example 8 The difference between Example 8 and Example 4 is that the synergist is fatty alcohol; the remaining steps are consistent with Example 4.

[0031] Example 9 The difference between Example 9 and Example 4 is that the synergist is sodium sulfate; the remaining steps are consistent with Example 4.

[0032] Comparative Example Comparative Example 1 Comparative Example 1 provides a method for preparing a demulsifier, comprising the following steps: 1 kg of calcium chloride, 1 kg of polyaluminium chloride, 0.7 kg of anionic polyacrylamide and 0.3 kg of ferrous sulfate were stirred and mixed to obtain a demulsifier.

[0033] Application Examples Application Example 1 Application Example 1 provides a demulsification process, comprising the following steps: Oil separation and demulsification: the waste emulsified liquid is added into the oil separation regulating tank, allowed to stand, and the mixed liquid at the lower layer is drawn into the demulsification reaction tank A containing the demulsifier in Example 1 for demulsification, oil and water separation, and the oil at the upper layer is the treated liquid A; wherein the weight ratio of the demulsifier to the waste emulsified liquid is 25:1000; Flocculation and precipitation: The treated liquid A is first passed into the demulsification reaction tank B with coagulant PAC, and then passed into the demulsification reaction tank C with flocculant PAM for flocculation and precipitation. The precipitation is located in the lower layer, and the treated liquid B is obtained in the upper layer; Adjusting pH: passing the treated liquid B into the demulsification reaction tank D, adding alkali to adjust the pH to 7, and obtaining the treated liquid C; wherein the alkali is sodium hydroxide; Sedimentation: The treated liquid C is passed into the sedimentation tank for static sedimentation, and the sludge is removed by filtration. The oil-water mixture is subjected to air flotation reaction to obtain the treated liquid D, and the demulsification is completed.

[0034] Application Example 2 The difference between Application Example 2 and Application Example 1 is that the demulsifier is the demulsifier in Example 2; the remaining steps are consistent with Application Example 1.

[0035] Application Example 3 The difference between Application Example 3 and Application Example 1 is that the demulsifier is the demulsifier in Example 3; the remaining steps are consistent with Application Example 1.

[0036] Application Example 4 The difference between Application Example 4 and Application Example 1 is that the demulsifier is the demulsifier in Example 4; the remaining steps are consistent with Application Example 1.

[0037] Application Example 5 The difference between Application Example 5 and Application Example 1 is that the demulsifier is the demulsifier in Example 5; the remaining steps are consistent with Application Example 1.

[0038] Application Example 6 The difference between Application Example 6 and Application Example 1 is that the demulsifier is the demulsifier in Example 6; the remaining steps are consistent with Application Example 1.

[0039] Application Example 7 The difference between Application Example 7 and Application Example 1 is that the demulsifier is the demulsifier in Example 7; the remaining steps are consistent with Application Example 1.

[0040] Application Example 8 The difference between Application Example 8 and Application Example 1 is that the demulsifier is the demulsifier in Example 8; the remaining steps are consistent with Application Example 1.

[0041] Application Example 9 The difference between Application Example 9 and Application Example 1 is that the demulsifier is the demulsifier in Example 9; the remaining steps are consistent with Application Example 1.

[0042] Application Example 10 The difference between Application Example 10 and Application Example 4 is that in the oil separation and demulsification step, the weight ratio of the demulsifier to the waste emulsion is 45:1000; the remaining steps are consistent with Application Example 4.

[0043] Application Example 11 The difference between Application Example 11 and Application Example 4 is that in the oil separation and demulsification step, the weight ratio of the demulsifier to the waste emulsion is 65:1000; the remaining steps are consistent with Application Example 4.

[0044] Application Example 12 The difference between Application Example 12 and Application Example 1 is that the demulsifier is the demulsifier in Comparative Example 1; the remaining steps are consistent with Application Example 1.

[0045] Performance testing Waste oil treatment effect: The original waste emulsion and the treated liquid D in the application example were sampled and tested separately, and the test was conducted in parallel 6 times. The average value was taken to obtain the COD, oil, ammonia nitrogen and sulfide content.

[0046] Table 1 Test results of waste oil Combining Application Examples 1-3 and Application Example 12, the demulsifier in Application Examples 1-3 has a better treatment effect on the waste emulsion. It can be seen that when preparing the demulsifier, surfactants, demulsifiers, synergists, and stabilizers are added. The surfactant first promotes the initial destruction of the emulsified structure of the oil-water mixture by reducing the interfacial tension, and then the demulsifier further strengthens this destruction process. Subsequently, the synergist interacts with the oil droplets to promote the coagulation of the oil droplets. Finally, the stabilizer forms a protective layer on its surface to prevent the oil droplets from emulsifying again. This series of processes together ensures the high efficiency of the demulsifier in treating the waste emulsion, thereby improving the treatment effect of the waste emulsion.

[0047] Combining Application Example 2, Application Example 4 and Application Example 5, the demulsifier in Application Example 4 has the best treatment effect on the waste emulsion. It can be seen that when preparing the demulsifier, the stirring temperature and time in Example 2 are optimal, thereby obtaining the best demulsification effect of the demulsifier.

[0048] In combination with Application Examples 4, 6 and 7, the demulsifier in Application Example 4 has the best treatment effect on the waste emulsion. It can be seen that when preparing the demulsifier, the demulsifier is preferably a mixture of polyacrylate and polymethacrylate. The molecular structure of polyacrylate enables it to form chemical bonds with water molecules and oil molecules in the demulsification process, further destroying the emulsified structure. Polymethacrylate is in the form of powder or gel, which is easy to be evenly dispersed in the mixture during stirring. Therefore, the synergistic effect of the two can be used to make the oil droplets in the emulsion agglomerate, thereby improving the treatment effect on the waste emulsion.

[0049] In combination with Application Examples 4, 8 and 9, the demulsifier in Application Example 4 has the best treatment effect on the waste emulsion. It can be seen that when preparing the demulsifier, the synergist is preferably a mixture of fatty alcohol and sodium sulfate. Fatty alcohol, as a surface-active compound, can adhere to the surface of oil droplets, change the surface properties of oil droplets, thereby reducing the repulsion between oil droplets and promoting oil droplet coagulation; the anions contained in sodium sulfate can interact with the ions on the surface of oil droplets, weaken the electrostatic repulsion between oil droplets, and the presence of sodium sulfate can increase the ionic strength in the solution. Therefore, the synergistic effect of the two is utilized to further improve the treatment effect of the waste emulsion.

[0050] Combining Application Example 4, Application Example 10 and Application Example 11, it can be seen that when demulsifier is used for demulsification, when the weight ratio of demulsifier to waste emulsified liquid is (25-65):1000, the demulsification effect on the waste emulsified liquid is better.

[0051] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A demulsifier for treating waste emulsion, characterized in that: The raw materials of the demulsifier include the following components in parts by weight: 1-1.2 parts of calcium chloride, 1-1.1 parts of polyaluminium chloride, 0.7-0.85 parts of anionic polyacrylamide, 0.3-0.5 parts of ferrous sulfate, 1-1.2 parts of surfactant, 0.4-0.5 parts of demulsifier, 0.1-0.2 parts of synergist and 0.1-0.2 parts of stabilizer.

2. A demulsifier for treating waste emulsion according to claim 1, characterized in that: The surfactant includes one or more of polyoxyethylene alkyl ether, fatty alcohol polyoxyethylene ether, and alkylphenol polyoxyethylene ether.

3. A demulsifier for treating waste emulsion according to claim 1, characterized in that: The demulsifier comprises a mixture of polyacrylate and polymethacrylate.

4. A demulsifier for treating waste emulsion according to claim 1, characterized in that: The synergist comprises a mixture of fatty alcohol and sodium sulfate.

5. A demulsifier for treating waste emulsion according to claim 1, characterized in that: The stabilizer includes glyceryl monostearate.

6. A demulsifier for treating waste emulsion according to claim 1, characterized in that: The preparation of the demulsifier comprises the following steps: First, the surfactant, demulsifier, synergist and stabilizer are stirred at 55-65° C. for 30-60 minutes, and the solvent is added during the stirring process to obtain a mixed liquid. Then calcium chloride, polyaluminum chloride, anionic polyacrylamide and ferrous sulfate are added and stirred to mix evenly to obtain a demulsifier.

7. A demulsification process, characterized in that: The following steps are involved: Oil separation and demulsification: adding the waste emulsified liquid into the oil separation and adjustment tank, letting it stand, extracting the mixed liquid at the lower layer and entering the demulsification reaction tank A containing the demulsifier according to any one of claims 1 to 6 for demulsification, and obtaining the treated liquid A after demulsification; Flocculation and precipitation: the treated liquid A is first passed into the demulsification reaction tank B with coagulant PAC, and then passed into the demulsification reaction tank C with flocculant PAM for flocculation and precipitation to obtain the treated liquid B; Adjust pH: pass the treated liquid B into the demulsification reaction tank D, add alkali to adjust the pH to 6-9, and obtain the treated liquid C; Sedimentation: Pass the treated liquid C into the sedimentation tank, let it settle, filter to remove the mud, and flotate the oil-water mixture to obtain the treated liquid D to complete the demulsification.

8. A demulsification process according to claim 7, characterized in that: In the oil separation and demulsification step, the weight ratio of the demulsifier to the waste emulsion is (25-65):1000.

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