A demulsification device and method for oily emulsified wastewater

Abstract

This invention discloses a demulsification device and method for oily emulsified wastewater. The demulsification device includes a raw liquid tank, a reaction tank, and a power source. The reaction tank includes an inlet near the bottom and a first outlet near the top, both connected to the raw liquid tank. A cylindrical penetrating titanium membrane electrode and a titanium mesh counter electrode are disposed within the reaction tank, with the titanium mesh counter electrode sleeved around the outer periphery of the penetrating titanium membrane electrode but not in contact. A second outlet is located above the internal cavity of the penetrating titanium membrane electrode and connected to the raw liquid tank. The positive terminal of the power source is connected to the penetrating titanium membrane electrode, and the negative terminal is connected to the titanium mesh counter electrode. This demulsification device utilizes anodic membrane interception and electrostatic adsorption to capture tiny oil droplets. An electric field is used to rearrange the surfactant groups in the oil droplets, and the oxidation effect of the anodic membrane destroys the surfactant groups at the oil-water interface, making the captured tiny oil droplets more prone to aggregation, ultimately achieving stratified demulsification.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, and specifically to a demulsification device and method for oily emulsified wastewater. Background Technology

[0002] With the rapid development of the petrochemical industry, traditional processes can no longer meet the increasingly complex water quality requirements. Currently, the main problems in treating electrostatic desalination wastewater are concentrated on the complexity of oils, the variety of organic matter, and the residue of demulsifiers. The oils in the multi-stage electrostatic desalination wastewater have been transformed into micron-sized oil-in-water and water-in-oil structures, resulting in complex oil-water interface properties. Compression of the electrostatic layer and netting / sweeping methods are no longer sufficient to destabilize and aggregate these colloidal oils. The emulsion particles are within 10 micrometers in size and possess a certain degree of stability. Simple gravity sedimentation cannot separate them from water; demulsification or flocculation is necessary. However, adding demulsifiers or flocculants often leads to secondary pollution and high costs.

[0003] Traditional treatment technologies include adsorption, gravity separation, centrifugal sedimentation, coagulation, and chemical degradation. Their main drawbacks are high cost and the potential for secondary pollution. Therefore, there is an urgent need for effective and environmentally friendly demulsification technologies that can efficiently demulsify without causing secondary pollution during the treatment process. Summary of the Invention

[0004] The purpose of this invention is to provide a demulsification device and method for oily emulsified wastewater. This demulsification device utilizes an anolyte membrane to trap and electrostatically adsorb tiny oil droplets. An electric field is used to rearrange the surfactant groups in the oil droplets, and the oxidation effect of the anolyte membrane destroys the surfactant groups at the oil-water interface, making it easier for the trapped tiny oil droplets to coalesce, ultimately achieving stratified demulsification.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The present invention provides a demulsification device for oily emulsified wastewater, comprising a raw liquid tank, a reaction tank, and a power source;

[0007] The reaction tank includes an inlet near the bottom of the tank and a first outlet near the top of the tank, which are respectively connected to the raw liquid tank.

[0008] The reaction tank is equipped with a cylindrical penetrating titanium film electrode and a titanium mesh electrode pair. The titanium mesh electrode pair is sleeved on the outer periphery of the penetrating titanium film electrode but does not contact it. A second water outlet is provided above the internal cavity of the penetrating titanium film electrode, and the second water outlet is connected to the raw liquid tank.

[0009] The positive terminal of the power supply is connected to the penetrating titanium film electrode, and the negative terminal is connected to the titanium mesh electrode.

[0010] According to the demulsification device of the present invention, preferably, both the reaction tank and the original liquid tank are vertical cylindrical.

[0011] According to the demulsification device of the present invention, preferably, both the original liquid tank and the reaction tank are equipped with a stirring device.

[0012] According to the demulsification device of the present invention, preferably, a peristaltic pump is provided on the connecting pipeline between the inlet, the first outlet and the second outlet of the reaction tank and the original liquid tank.

[0013] According to the demulsification device of the present invention, preferably, both the penetrating titanium film electrode and the titanium mesh electrode are cylindrical.

[0014] According to the demulsification device of the present invention, preferably, the pore size of the membrane pores on the penetrating titanium membrane electrode is 0.5 μm to 20 μm; more preferably, it is 1 μm to 5 μm.

[0015] According to the demulsification device of the present invention, preferably, the gap distance between the titanium mesh electrode and the penetrating titanium film electrode is 0.5cm to 5cm.

[0016] According to the demulsifying apparatus of the present invention, preferably, the demulsifying method is carried out using the above-described demulsifying apparatus.

[0017] According to the demulsifying apparatus of the present invention, preferably, the demulsifying method comprises the following processes:

[0018] The oily emulsified wastewater in the raw solution tank is introduced from the inlet of the reaction tank and then discharged from the first outlet, forming an upward water flow. At the same time, the effluent from the permeable titanium membrane electrode is discharged into the raw solution tank from the second outlet, forming a cross-flow filtration with the water flow outside the permeable titanium membrane electrode. Tiny oil droplets in the oily emulsified wastewater are intercepted and adsorbed on the surface of the permeable titanium membrane electrode through membrane pore sieving and electrostatic attraction. The captured oil droplets aggregate on the membrane surface of the permeable titanium membrane electrode, forming an oil film. Under the action of fluid shear force, they desorb and float to the surface, becoming an oil layer separated from the emulsion phase.

[0019] According to the demulsification method of the present invention, preferably, the oil layer enters the floating oil collection tank.

[0020] According to the demulsification method of the present invention, preferably, the COD content in the oily emulsified wastewater is 200 mg / L to 15000 mg / L.

[0021] According to the demulsification method of the present invention, preferably, the reaction time of the demulsification method is 10 min to 120 min.

[0022] The beneficial effects of this invention include:

[0023] 1) The demulsification device of the present invention uses an anode membrane (penetrating titanium membrane electrode) to trap and electrostatically adsorb tiny oil droplets. The surfactant groups of the oil droplets are rearranged by the action of an electric field. The oxidation effect of the anode membrane is used to destroy the surfactant groups at the oil-water interface, making it easier for the trapped tiny oil droplets to coalesce, and finally achieving layered demulsification, which solves the problem of poor demulsification effect in the existing devices.

[0024] 2) The demulsification device and method of the present invention do not require the addition of chemical agents and do not cause secondary pollution during operation, thus solving the problems of high cost and secondary pollution to the environment caused by reagent demulsification in existing traditional demulsification methods. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the demulsification device for emulsified oily wastewater in a preferred embodiment of the present invention.

[0026] Figure 2 This is a cross-sectional view of the reaction tank in a preferred embodiment of the present invention.

[0027] Figure 3 This is a top view of the reaction tank in a preferred embodiment of the present invention.

[0028] Figure 4 This is a cross-sectional view of a through-type titanium film electrode in a preferred embodiment of the present invention.

[0029] Figure 5 The image shows the effect of emulsion demulsification treatment in Test Example 1.

[0030] Figure 6 This is a comparison chart of the demulsification effects of different inorganic salts in Test Example 2.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1-Stock solution tank;

[0033] 2-Reaction tank;

[0034] 3-Penetrating titanium film electrode;

[0035] 4-Titanium mesh counter electrode;

[0036] 5-Power supply;

[0037] 6-First outlet;

[0038] 7-Second outlet;

[0039] 8-Water inlet;

[0040] 9, 10 - Power connection cable;

[0041] 11-First connecting catheter;

[0042] 12-Second connecting catheter;

[0043] 13-Third connecting catheter;

[0044] 14, 15, 16 - Peristaltic pumps;

[0045] 17-Titanium mesh counter electrode tabs;

[0046] 18 - Internal cavity of the penetrating membrane electrode;

[0047] 19 - Outer wall of penetrating titanium film electrode. Detailed Implementation

[0048] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further clarifies the invention. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0049] This invention provides a preferred embodiment, such as... Figures 1-4 As shown, an environmentally friendly green demulsification device for emulsified oily wastewater includes a raw liquid tank 1, a reaction tank 2, and a power source 5.

[0050] Both the raw material tank 1 and the reaction tank 2 are vertical cylindrical. The reaction tank 2 includes an inlet 8 near the bottom of the tank and a first outlet 6 near the top of the tank.

[0051] The inlet 8 is connected to the raw liquid tank 1 via a first connecting conduit 11, and a peristaltic pump 14 is installed on the first connecting conduit 11. The outlet 6 is connected to the raw liquid tank 1 via a second connecting conduit 12, and a peristaltic pump 16 is installed on the second connecting conduit 12.

[0052] Both the raw material tank 1 and the reaction tank 2 have their water flow controlled by magnetic stirrers. Reaction tank 2 is the main unit of the demulsification reactor, used to enhance the demulsification effect. Figure 2 and Figure 3 As shown, the reaction tank 2 is equipped with a penetrating titanium film electrode 3 and a titanium mesh counter electrode 4, both of which are cylindrical. The titanium mesh counter electrode 4 is sleeved around the outer periphery of the penetrating titanium film electrode 3 but does not contact it. Figures 2-4 As shown, the penetrating titanium film electrode 3 is cylindrical, and the outer wall 19 of the penetrating titanium film electrode surrounds and forms an internal cavity 18. A second water outlet 7 is provided above the internal cavity 18. Figure 1 As shown, the second outlet 7 is connected to the original liquid tank 1 via a third connecting conduit 13, and a peristaltic pump 15 is installed on the third connecting conduit 13.

[0053] The positive terminal of the power supply 5 is connected to the penetrating titanium film electrode 3 via a power connection line 10, and the negative terminal is connected to the titanium mesh counter electrode 4 via a power connection line 9, specifically connected to the titanium mesh counter electrode tab 17.

[0054] The pore size of the perforated membrane is preferably 0.5 μm to 20 μm. The gap distance between the titanium mesh electrode 4 and the perforated titanium membrane electrode 3 is preferably 0.5 cm to 5 cm.

[0055] use Figure 1 The process of demulsifying oily emulsified wastewater using a demulsifier is as follows:

[0056] Oily emulsified wastewater from the raw solution tank 1 is introduced into the reaction tank 2 via the inlet 8 at the bottom by a peristaltic pump 14, and then discharged via the first outlet 6 at the top by a peristaltic pump 16. Simultaneously, the effluent from the permeable titanium membrane electrode 3 is drawn into the raw solution tank 1 via the second outlet 7 by a peristaltic pump 15, forming a cross-flow filtration with the external water flow of the permeable titanium membrane electrode 3. During operation, tiny oil droplets are trapped and adsorbed on the surface of the permeable titanium membrane electrode 3 through membrane pore sieving and electrostatic attraction. The captured oil droplets coalesce on the membrane surface, and the surfactant groups of the oil droplets are rearranged by the electric field. The oxidation effect of the anolyte membrane destroys the surfactant groups at the oil-water interface, making it easier for the captured tiny oil droplets to coalesce. After forming an oil film, it desorbs and floats under the action of fluid shear force, becoming an oil layer separated from the emulsion phase and entering the floating oil collection tank.

[0057] Test Example 1:

[0058] This test example uses the above apparatus and method to demulsify emulsion wastewater with an oil concentration of 1%. The voltage is set to 0V or 5V, and the membrane pore size is 1μm or 5μm. COD is measured from the reaction tank at different reaction times, and the COD removal rate is calculated based on the initial COD. The results are as follows: Figure 5 As shown, the COD removal rate was significantly higher at 5V compared to the 0V experimental group, indicating that increasing the voltage facilitates the rapid occurrence of the electrochemical process. The COD removal rate in the emulsion wastewater decreased as the membrane electrode pore size increased from 1μm to 5μm. Furthermore, the COD removal rate increased with operating time under different conditions, but the increase slowed down after 40 minutes.

[0059] After the above process, 1% of the emulsion wastewater (with an average oil droplet diameter of less than 10 micrometers) was treated, the oil layer floated to the surface, and the COD concentration removal rate reached more than 90%.

[0060] Test Example 2:

[0061] This test case investigates the effect of the presence of inorganic salts on the demulsification effect of the demulsification device of this invention in actual oily wastewater containing salt. The voltage was set to 3V, and the membrane pore size was 1μm. The effects of two different types of inorganic salts, sodium sulfate and sodium chloride, on the demulsification process were examined. Specifically, the concentration of sodium sulfate in the 1% oil emulsion wastewater was 10mM, and the concentration of sodium chloride was 30mM. The experimental results are as follows: Figure 6 As shown, the COD removal rates of the emulsions under the three inorganic salt conditions were 86.9% (without inorganic salts), 91.6% (with sodium sulfate), and 92.4% (with sodium chloride), respectively. Comparing the demulsification effect of the emulsions under different inorganic salt conditions, it was found that the demulsification device achieved a better COD removal rate in the emulsion containing inorganic salts than in the case without inorganic salts.

[0062] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for demulsifying oily emulsified wastewater, characterized in that, The demulsification device for implementing the demulsification method includes a raw liquid tank, a reaction tank, and a power supply; The reaction tank includes an inlet near the bottom of the tank and a first outlet near the top of the tank, which are respectively connected to the raw liquid tank. The reaction tank is equipped with a cylindrical penetrating titanium film electrode and a titanium mesh electrode pair. The titanium mesh electrode pair is sleeved on the outer periphery of the penetrating titanium film electrode but does not contact it. A second water outlet is provided above the internal cavity of the penetrating titanium film electrode, and the second water outlet is connected to the raw liquid tank. The positive terminal of the power supply is connected to the penetrating titanium film electrode, and the negative terminal is connected to the titanium mesh electrode. The process of the demulsification method is as follows: The oily emulsified wastewater in the raw solution tank is introduced from the inlet of the reaction tank and then discharged from the first outlet, forming an upward water flow. At the same time, the effluent from the permeable titanium membrane electrode is discharged into the raw solution tank from the second outlet, forming a cross-flow filtration with the water flow outside the permeable titanium membrane electrode. Tiny oil droplets in the oily emulsified wastewater are intercepted and adsorbed on the surface of the permeable titanium membrane electrode through membrane pore sieving and electrostatic attraction. The captured oil droplets aggregate on the membrane surface of the permeable titanium membrane electrode, forming an oil film. Under the action of fluid shear force, they desorb and float to the surface, becoming an oil layer separated from the emulsion phase.

2. The demulsification method according to claim 1, characterized in that, The oil layer enters the floating oil collection tank.

3. The demulsification method according to claim 1, characterized in that, The COD content in the oily emulsified wastewater is 200 mg / L ~ 15000 mg / L.

4. The demulsification method according to claim 1, characterized in that, The demulsification method has a reaction time of 10 min to 120 min.

5. An apparatus for treating oily emulsified wastewater, used to implement the demulsification method according to any one of claims 1-4.

6. The demulsifying device according to claim 5, characterized in that, Both the reaction tank and the raw liquid tank are vertical cylindrical.

7. The demulsifying device according to claim 5, characterized in that, Both the stock solution tank and the reaction tank are equipped with stirring devices.

8. The demulsifying device according to claim 5, characterized in that, Peristaltic pumps are installed on the connecting pipes between the inlet, first outlet, and second outlet of the reaction tank and the raw liquid tank.

9. The demulsifying device according to claim 5, characterized in that, Both the penetrating titanium film electrode and the titanium mesh electrode are cylindrical.

10. The demulsifying device according to claim 5, characterized in that, The pore size of the membrane pores on the penetrating titanium membrane electrode is 0.5 μm ~ 20 μm.

11. The demulsifying device according to claim 5, characterized in that, The gap between the titanium mesh electrode and the penetrating titanium film electrode is 0.5 cm to 5 cm.

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