Composite demulsifier with adsorption bridging effect as well as preparation method and application of composite demulsifier

Abstract

The invention discloses a composite demulsifier with an adsorption bridging effect. The composite demulsifier is composed of polyaluminum chloride, polyaluminum ferric chloride and deionized water, wherein the mass ratio of polyaluminum chloride to polyaluminum ferric chloride is (1-4): 1; compared with the prior art, the method has the advantages that aluminum ions and iron ions play a differentiated role in stages in the demulsification process: firstly, Fe < 3 + > of polyaluminum ferric chloride is combined with organic molecules (such as fatty acid) on the surfaces of oil drops through coordinate bonds to form a Fe-organic complex, so that the hydrophobicity of floc is enhanced; meanwhile, hydrolysis products (such as Fe (OH) 3 colloid) of Fe < 3 + > are filled in floc gaps, so that the structural compactness is improved, and floc reinforcement is realized; long-chain macromolecules of the polyaluminum ferric chloride stretch under shearing force, dispersed flocs are connected into clusters with the diameter larger than 500 micrometers through molecular chain winding, the shearing strength is improved, and stable bridging is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of demulsifiers, and in particular to a composite demulsifier with adsorption bridging effect, a preparation method thereof and an application thereof. Background Art

[0002] In the process of industrial wastewater treatment, the treatment of high-concentration emulsified oil wastewater has become a technical bottleneck that urgently needs to be broken through. This type of wastewater is widely found in industries such as petrochemicals, metal processing, and machinery manufacturing. Its oil droplet size is small (usually <10μm), the surface charge is stable (Zeta potential <-30mV), and it often contains complex components such as surfactants and metal ions, forming a highly stable emulsion system. Traditional demulsification technology has difficulty in efficiently separating the oil and water phases, leading to problems such as blockage of the circulating water system, equipment corrosion, and secondary pollution, which seriously restricts the sustainable development of industrial production. At present, the industry mainly relies on chemical demulsifiers to achieve oil-water separation, among which inorganic and organic polymers are widely used due to their charge neutralization ability, but there are still significant limitations.

[0003] For example, polyaluminium chloride (PAC) can pass through Al 3+ It can quickly neutralize the negative charge on the surface of oil droplets, but its molecular weight is low (usually less than 8 million), and the flocs formed are loose and fragile, and are easy to disperse again under shear force; Polyaluminium Ferric Chloride (PAFC) contains Fe 3+ , has a high molecular weight (>10 million), but has a weak charge neutralization efficiency and is difficult to handle high-stability emulsions alone.

[0004] Specifically, CN119569202A discloses the use of PAC-based demulsifiers to improve Al 3+ Concentration enhances charge neutralization, but does not solve the problem of fragile floc structure; because the degree of polymerization of PAC is adjusted by alkalinity, the Al13 polynuclear structure in PAC is easily depolymerized when pH>8, which limits the applicable pH range.

[0005] In recent years, researchers have tried to improve the performance of composite demulsifiers or polymer modification. For example, CN119258598A proposed combining PAC with ferrous sulfate to improve the performance of the composite demulsifier. 2+ / Al 3+ Mixed hydrolysis generates composite flocs, but Fe 2 + Easily oxidized to Fe 3+ , resulting in harsh reaction conditions (strict oxygen control is required), and residual iron ions may cause water color problems.

[0006] Meanwhile, a kind of multipurpose synthetic purifier is proposed in CN119263428A, it is made up of ferric chloride, polyaluminium chloride ferric, dihydrate calcium chloride, ferrous sulfate, polyaluminium chloride and basic aluminium chloride, and the invention passes through the multiple effects such as ion exchange, demulsification, flocculation, adsorption redox;COD in waste water can be quickly removed, pH is neutralized, hydrophilicity is changed, compression diffusion layer, increases counterion effect, and finally reaches the purpose of redox. However, the method has certain deficiencies in actual applications, and there is mutual interference between complicated composition, such as basic aluminium chloride may produce precipitation with ferric chloride, ferrous sulfate and dihydrate calcium chloride etc. during hydrolysis, so as to cause effective ingredient to reduce;Ferric chloride, ferrous sulfate, polyaluminium chloride and basic aluminium chloride with electrical neutralization may cause excessive charge neutralization in water in a large amount, affect the adsorption bridging effect of polyaluminium chloride ferric on the contrary, so as to suppress its demulsification effect. To maintain the treatment effect of the reaction system, the ratio of the added purifier to water is as high as 1:1, and the ratio of polyacrylamide to synthetic purifier reaches 1:1.5-2. The higher amount of purifier added not only increases the cost of the agent, but also significantly increases the total water volume, resulting in increased water treatment operating costs; in addition, calcium chloride dihydrate easily forms precipitation with carbonate or hydroxide in the wastewater during use, causing operational problems such as scaling and clogging of the dosing equipment.

[0007] While these improvements have partially enhanced demulsification performance, key challenges remain: poor adaptability to high-concentration emulsified oil wastewater and insufficient floc stability. Furthermore, some demulsifiers rely on precious metals or complex processes, making them difficult to scale up. Therefore, the development of a low-cost, highly adaptable, and floc-stabilizing composite demulsifier is an urgent need for advanced industrial wastewater treatment. Summary of the Invention

[0008] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a composite demulsifier with adsorption bridging effect and its preparation method and application, so as to solve the problems of high cost, poor adaptability and insufficient floc stability of the composite demulsifier in the prior art.

[0009] To achieve the above objectives, the first aspect of the present invention adopts the following technical solution: a composite demulsifier with an adsorption bridging effect, wherein the composite demulsifier is composed of polyaluminum chloride, polyaluminum ferric chloride and deionized water, and the mass ratio of polyaluminum chloride to polyaluminum ferric chloride is 1 to 4:1.

[0010] The inventor unexpectedly discovered that the combination of polyaluminum chloride and polyaluminum ferric chloride has a compatibility effect in the demulsification process, and the demulsification mechanism is as follows:

[0011] The aluminum-based polymer of polyaluminum chloride and the iron-aluminum composite polymer of polyaluminum ferric chloride are bridged by hydroxyl (-OH) to form a "bimetallic multinuclear complex", that is, the polymer chain forms a "network structure", which adsorbs and aggregates oil droplets through the adsorption bridging effect of the multinuclear complex; the iron-based polymer of polyaluminum ferric chloride has a larger molecular weight, which enhances the demulsification ability of high-concentration emulsified oil (such as oily wastewater from aluminum rolling); aluminum ions quickly neutralize the negative charge on the colloid surface, and iron ions enhance the stability of flocs, synergistically forming strong and tough large flocs.

[0012] Specifically: First, Fe in polyaluminium ferric chloride 3+ The strong coordination ability of polyaluminium chloride preferentially combines with the negatively charged groups (such as -COO-, -SO3-) on the surface of the oil droplet to form the initial adsorption site; secondly, the Al 3+ Through hydroxyl groups and Fe 3+ Connect to form Al-O-Fe bonds, build a three-dimensional network skeleton to achieve bridging expansion; then the free Al 13 O4(OH) 24 (H2O) 12 7+ and Fe6O3(OH) 18 (H2O)9 9+ The polynuclear bodies are further cross-linked to form a network structure with a pore size of 10-50nm, which can capture multiple oil droplets at the same time and achieve network densification; this structure significantly increases the probability of oil droplet collision through the dual effects of "steric hindrance effect" and "multi-point anchoring", and the aggregation efficiency is 2-3 times higher than that of a single component.

[0013] Furthermore, the composite demulsifier is a solution with a concentration of 100 g / L.

[0014] Furthermore, the molecular weight of the polyaluminium chloride is 5 million to 8 million, and the molecular weight of polyaluminium ferric chloride is 8 million to 12 million.

[0015] The second aspect of the present invention adopts the following technical solution: a method for preparing the composite demulsifier with adsorption bridging effect described in the first aspect of the present invention, comprising the following steps:

[0016] Weigh polyaluminium chloride, polyaluminium ferric chloride and deionized water;

[0017] Add polyaluminium chloride and polyaluminium ferric chloride into deionised water and stir until completely dissolved.

[0018] Furthermore, the stirring speed used during the stirring process is 600-800 rpm, and the stirring time is 30-60 min.

[0019] The third aspect of the present invention adopts the following technical solution: an application, which applies the composite demulsifier with adsorption bridging effect described in the first aspect of the present invention to aluminum rolling oily wastewater for demulsification.

[0020] Furthermore, the use process of the composite demulsifier with adsorption bridging effect is as follows:

[0021] Adjusting pH: adding a pH regulator to the oily wastewater to adjust the pH to 6.0-10.0 to obtain a treated solution A;

[0022] Demulsification: Add demulsifier to treatment liquid A at an amount of 35-80 mg / L, stir and mix, and let it stand to obtain treatment liquid B;

[0023] Flocculation precipitation: Add a coagulant at a rate of 100-160 mg / L to the treated liquid B, stir and mix, then add a flocculant at a rate of 10-40 mg / L to the treated liquid B, let it stand until flocs are formed, and then separate the oil phase.

[0024] Furthermore, the pH regulator is sodium hydroxide.

[0025] Furthermore, the coagulant is polyaluminium chloride.

[0026] Furthermore, the flocculant is polyacrylamide.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The composite demulsifier with adsorption bridging effect of the present invention plays a differentiated role in the demulsification process in stages through aluminum and iron ions: first, Fe 3+ Through coordination bonds, Fe binds to organic molecules (such as fatty acids) on the surface of oil droplets to form Fe-organic complexes, which enhance the hydrophobicity of flocs. 3+ The hydrolysis products (such as Fe(OH)3 colloid) fill the gaps between the flocs, improve the structural density, and achieve floc strengthening; the long-chain polymers of polyaluminum ferric chloride stretch under shear force, and through "molecular chain entanglement", the dispersed flocs are connected into clusters with a diameter of >500μm, which improves the shear strength and achieves bridging stability.

[0029] 2. The composite demulsifier with adsorption bridging effect prepared by the present invention has high demulsification efficiency and strong adaptability, overcoming the problems that the traditional single polymer cannot construct a multi-dimensional structure with both charge neutralization and adsorption bridging; has poor adaptability to high-salt and high-COD wastewater, insufficient floc stability; and is difficult to apply on a large scale.

[0030] 3. Add the demulsifier to the oily wastewater after adjusting the pH at the preferred concentration, stir and mix thoroughly to achieve effective demulsification of the oily wastewater; further add the coagulant, stir and mix, then introduce the flocculant, stir and mix thoroughly to achieve rapid flocculation and precipitation of the treated liquid, let it stand to form flocs and then separate the oil phase to achieve efficient treatment of the oily wastewater.

[0031] 4. Fe in the polyaluminium ferric chloride of the present invention 3+ With Ca 2+ Competitive binding to the colloid surface reduces the disintegration of flocs caused by the "salt effect" and achieves effective anti-ion interference. In the pH range of 6-10, the Fe(OH)3 colloid of polyaluminum ferric chloride and the Al(OH)3 colloid of polyaluminum chloride form a complementary buffer system to maintain the stability of the flocs and achieve pH self-adaptation. The hydrophobic area of ​​the Al-Fe polynuclear body (such as Al-O-Fe bond) can adsorb non-ionic surfactants (such as TX-100) to form a "micelle-floc complex" to avoid the inhibition of surfactants on demulsification. It can be used for high concentration (>5000 mg / L) and complex emulsification systems (such as Na + , Ca 2+ , surfactants), and has broad spectrum applicability.

[0032] 5. The dosage of the composite demulsifier of the present invention reduces damage to the environment, achieves the effects of cost reduction, efficiency improvement, environmental protection and energy saving, and can be widely used in the treatment of oily wastewater in the fields of petrochemical industry, metal processing, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The performance comparison chart of Application Example 1, Application Example 2 and Application Example 3 is as follows;

[0034] Figure 2 This is a performance comparison chart of Application Example 3, Application Example 4, and Application Example 5;

[0035] Figure 3 This is a performance comparison chart of Application Example 3 and Application Examples 7-10;

[0036] Figure 4 This is a performance comparison chart of Application Example 3 and Application Examples 11-13;

[0037] Figure 5 This is a performance comparison chart of Application Example 3, Application Example 14, and Application Example 15;

[0038] Figure 6 This is a performance comparison chart of Application Example 11, Application Example 16, and Application Example 17;

[0039] Figure 7 The performance comparison chart of Application Example 3 and Application Example 6 is shown in FIG. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below through specific embodiments:

[0041] Example 1

[0042] Preparation of composite demulsifier with adsorption bridging effect

[0043] S1: Weigh 70g of polyaluminium chloride with a molecular weight of 5-8 million and 30g of polyaluminium ferric chloride with a molecular weight of 8-12 million and mix them;

[0044] S2: After mixing, add 900 mL of deionized water, stir at 500 rpm for 40 minutes, and adjust the volume to 1 L to obtain a 100 g / L demulsifier solution.

[0045] Example 2

[0046] Preparation of composite demulsifier with adsorption bridging effect

[0047] S1: Weigh 80g of polyaluminium chloride with a molecular weight of 5-8 million and 20g of polyaluminium ferric chloride with a molecular weight of 8-12 million and mix them;

[0048] S2: After mixing, add 900 mL of deionized water, stir at 500 rpm for 40 minutes, and adjust the volume to 1 L to obtain a 100 g / L demulsifier solution.

[0049] Example 3

[0050] Preparation of composite demulsifier with adsorption bridging effect

[0051] S1: Weigh 50g of polyaluminium chloride with a molecular weight of 5-8 million and 50g of polyaluminium ferric chloride with a molecular weight of 8-12 million and mix them;

[0052] S2: After mixing, add 900 mL of deionized water, stir at 500 rpm for 40 minutes, and adjust the volume to 1 L to obtain a 100 g / L demulsifier solution.

[0053] Comparative Example 1

[0054] Preparation of single demulsifier

[0055] S1: Weigh 100g of polyaluminium chloride with a molecular weight of 6 million;

[0056] S2: Add polyaluminum chloride to 900 mL of deionized water, stir at 500 rpm for 40 minutes, and dilute to 1 L to obtain a 100 g / L demulsifier solution.

[0057] Comparative Example 2

[0058] Preparation of single demulsifier

[0059] S1: Weigh 100g of polyaluminium ferric chloride with a molecular weight of 12 million;

[0060] S2: Add polyaluminium ferric chloride to 900 mL of deionized water, stir at 500 rpm for 40 minutes, and dilute to 1 L to obtain a 100 g / L demulsifier solution.

[0061] Application Example 1

[0062] The demulsification process of the composite demulsifier includes the following steps:

[0063] (1) pH adjustment: 500 mL of oily wastewater (oil concentration 6500 mg / L, pH = 3.5) was taken and sodium hydroxide was added to adjust the pH of the wastewater to 7.0 to obtain treated solution A;

[0064] (2) Demulsification: The demulsifier prepared in Example 1 was added to the treated liquid A at an addition amount of 50 mg / L, stirred and mixed, and allowed to stand for 5 minutes to obtain the treated liquid B;

[0065] (3) Flocculation precipitation: Add polyaluminium chloride at a rate of 160 mg / L to the treated liquid B, stir and mix, then add polyacrylamide at a rate of 10 mg / L to the treated liquid B, let it stand for 10 to 30 minutes, form flocs, and then separate the oil phase;

[0066] (4) Performance testing: COD, petroleum, SS and color of the treated water samples are measured.

[0067] Application Example 2

[0068] The only difference from Application Example 1 is that the demulsifier prepared in Example 1 is replaced by the demulsifier prepared in Example 2.

[0069] Application Example 3

[0070] The only difference from Application Example 1 is that the demulsifier prepared in Example 1 is replaced by the demulsifier prepared in Example 3.

[0071] Application Example 4

[0072] The only difference from Application Example 1 is that the demulsifier prepared in Example 1 is replaced by the demulsifier prepared in Comparative Example 1.

[0073] Application Example 5

[0074] The only difference from Application Example 1 is that the demulsifier prepared in Example 1 is replaced by the demulsifier prepared in Comparative Example 2.

[0075] Application Example 6

[0076] The only difference from Application Example 1 is that the demulsifier prepared in Example 1 is replaced by a traditional commercial demulsifier (prepared by Chongqing Xinren Environmental Protection Technology Co., Ltd.).

[0077] Application Example 7

[0078] The only difference from Application Example 3 is that sodium hydroxide is added to adjust the pH of the wastewater to 6.0.

[0079] Application Example 8

[0080] The only difference from Application Example 3 is that sodium hydroxide is added to adjust the pH of the wastewater to 8.0.

[0081] Application Example 9

[0082] The only difference from Application Example 3 is that sodium hydroxide is added to adjust the pH of the wastewater to 9.0.

[0083] Application Example 10

[0084] The only difference from Application Example 3 is that sodium hydroxide is added to adjust the pH of the wastewater to 10.0.

[0085] Application Example 11

[0086] The only difference from Application Example 3 is that the addition amount of the demulsifier is adjusted to 35 mg / L, the addition amount of polyaluminum chloride is adjusted to 160 mg / L, and the addition amount of polyacrylamide is adjusted to 10 mg / L.

[0087] Application Example 12

[0088] The only difference from Application Example 3 is that the addition amount of the demulsifier is adjusted to 65 mg / L, the addition amount of polyaluminum chloride is adjusted to 160 mg / L, and the addition amount of polyacrylamide is adjusted to 10 mg / L.

[0089] Application Example 13

[0090] The only difference from Application Example 3 is that the addition amount of the demulsifier is adjusted to 80 mg / L, the addition amount of polyaluminum chloride is adjusted to 160 mg / L, and the addition amount of polyacrylamide is adjusted to 10 mg / L.

[0091] Application Example 14

[0092] The only difference from Application Example 3 is that the addition amount of the demulsifier is adjusted to 50 mg / L, the addition amount of polyaluminum chloride is adjusted to 100 mg / L, and the addition amount of polyacrylamide is adjusted to 10 mg / L.

[0093] Application Example 15

[0094] The only difference from Application Example 3 is that the addition amount of the demulsifier is adjusted to 50 mg / L, the addition amount of polyaluminum chloride is adjusted to 130 mg / L, and the addition amount of polyacrylamide is adjusted to 10 mg / L.

[0095] Application Example 16

[0096] The only difference from Application Example 3 is that the addition amount of the demulsifier is adjusted to 35 mg / L, the addition amount of polyaluminum chloride is adjusted to 160 mg / L, and the addition amount of polyacrylamide is adjusted to 25 mg / L.

[0097] Application Example 17

[0098] The only difference from Application Example 3 is that the addition amount of the demulsifier is adjusted to 35 mg / L, the addition amount of polyaluminum chloride is adjusted to 160 mg / L, and the addition amount of polyacrylamide is adjusted to 40 mg / L.

[0099] Performance tests were performed on use cases 1-17, and the data shown in Table 1 was obtained.

[0100]

[0101]

[0102] Table 1

[0103] The optimization process of the ratio of polyaluminium chloride and polyaluminium ferric chloride can be combined with application examples 1, 2 and 3 to obtain the corresponding COD, petroleum and suspended solids removal efficiency diagrams. Figure 1 As shown in the figure, the demulsifier in Application Example 3 has the best treatment effect on aluminum rolling wastewater, and the removal efficiencies of COD, petroleum and suspended solids are 84.89%, 72.68% and 92.76% respectively. It can be seen that the composite demulsifier prepared by using polyaluminum chloride and polyaluminum ferric chloride has the best ratio of 1:1 by mass, which can fully utilize the synergistic effect of polyaluminum chloride and polyaluminum ferric chloride to construct a multi-dimensional structure with both charge neutralization and adsorption bridging, so that the floc structure is stable, thereby improving the treatment effect of aluminum rolling wastewater.

[0104] Combining the COD, petroleum and suspended solids concentration values ​​of Application Examples 3, 4 and 5, the corresponding removal efficiency graph can be obtained. Figure 2As shown in the figure, the removal efficiency of COD, petroleum and suspended solids of single polyaluminium chloride is the lowest, which are 35.1%, 57.17% and 67.58% respectively; all of them are far lower than the treatment effect of composite demulsifier on aluminum rolling wastewater. Although the effect of single polyaluminium chloride ferric is improved compared with single polyaluminium chloride, it is still lower than that of composite demulsifier, and the cost of single polyaluminium chloride ferric is relatively high. It can be seen that the composite demulsifier prepared by polyaluminium chloride and polyaluminium chloride ferric has an adsorption bridging effect, which can not only shorten the reaction precipitation time, but also improve the stability of flocs, facilitate subsequent solid-liquid separation, and help reduce the dosage of reagents and operating costs.

[0105] Combining the COD, petroleum and suspended solids concentration values ​​of Application Example 3 and Application Examples 7-10, the corresponding removal efficiency diagram can be obtained. Figure 3 As shown in the figure, under the condition of pH 6.0-10.0, the removal rates of COD, petroleum and suspended solids are relatively small, indicating that the composite demulsifier is less restricted by pH and has a wide range of applications.

[0106] Combining the COD, petroleum and suspended solids concentration values ​​of Application Example 3 and Application Examples 7-10, the corresponding removal efficiency diagram can be obtained. Figure 4 As shown in the figure, by adjusting the amount of demulsifier used, it can be found that when the amount of demulsifier used is 50 mg / L, the removal effect is the best. Combining the COD, petroleum and suspended solids concentration values ​​of Application Examples 3 and 14-15, the corresponding removal efficiency diagram can be obtained. Figure 5 As shown in the figure, the removal efficiency increases continuously with the increase of the amount of polyaluminium chloride used as a coagulant, and the optimal amount is determined to be 160 mg / L. Combining the COD, petroleum and suspended solids concentration values ​​of Application Example 11 and Application Examples 16-17, the corresponding removal efficiency graph can be obtained. Figure 6 As shown in the figure, with the increase of the dosage of polyacrylamide, there is no significant difference in the treatment effect, so the optimal dosage of polyacrylamide is 10 mg / L.

[0107] By comparing Application Example 3 and Application Example 6, we can get the removal efficiency diagram of COD, petroleum and suspended solids of composite demulsifier and commercial demulsifier. Figure 7 As shown, the treatment effect of Application Example 3 is better than that of Application Example 6 in all indicators. The removal rates of COD, petroleum and suspended solids by commercial demulsifiers are 43%, 59.84% and 88.2% respectively, while the removal rates of COD, petroleum and suspended solids in sewage by the composite demulsifier of Application Example 3 are increased by 41.89%, 12.84% and 4.56% respectively compared with Application Example 6.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A composite demulsifier with adsorption bridging effect, characterized in that: The composite demulsifier is composed of polyaluminum chloride, polyaluminum ferric chloride and deionized water, and the mass ratio of polyaluminum chloride to polyaluminum ferric chloride is 1 to 4:

1.

2. The composite demulsifier with adsorption bridging effect according to claim 1, characterized in that: The composite demulsifier is a solution with a concentration of 100 g / L.

3. The composite demulsifier with adsorption bridging effect according to claim 1, characterized in that: The molecular weight of the polyaluminium chloride is 5 million to 8 million, and the molecular weight of the polyaluminium ferric chloride is 8 million to 12 million.

4. A method for preparing the composite demulsifier with adsorption bridging effect according to any one of claims 1 to 3, characterized in that: The following steps are involved: Weigh polyaluminium chloride, polyaluminium ferric chloride and deionized water; Add polyaluminium chloride and polyaluminium ferric chloride into deionised water and stir until completely dissolved.

5. The method for preparing a composite demulsifier having an adsorption bridging effect according to claim 4, wherein: The stirring speed used during the stirring process is 600-800 rpm, and the stirring time is 30-60 min.

6. An application, characterized in that: The composite demulsifier with adsorption bridging effect according to any one of claims 1 to 3 is applied to aluminum rolling oily wastewater to demulsify the oily wastewater.

7. The use according to claim 6, characterized in that: The use process of the composite demulsifier with adsorption bridging effect is as follows: Adjusting pH: adding a pH regulator to the oily wastewater to adjust the pH to 6.0-10.0 to obtain a treated solution A; Demulsification: Add demulsifier to treatment liquid A at an amount of 35-80 mg / L, stir and mix, and let it stand to obtain treatment liquid B; Flocculation precipitation: Add a coagulant at a rate of 100-160 mg / L to the treated liquid B, stir and mix, then add a flocculant at a rate of 10-40 mg / L to the treated liquid B, let it stand until flocs are formed, and then separate the oil phase.

8. The use according to claim 7, characterized in that: The pH regulator is sodium hydroxide.

9. The use according to claim 7, characterized in that: The coagulant is polyaluminium chloride.

10. The use according to claim 7, characterized in that: The flocculant is polyacrylamide.

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