JPH1085563A - Separation of oil from waste water containing emulsified oil and device using this oil/water separation process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for separating oil from waste water from containing emulsified oil by which it is possible to perform oil/water separation at a higher pH value and remove contaminants from a diaphragm and an electrode by a simple means. SOLUTION: In a method for separating surfactant and the oil emulsified through its chemical reaction with the surfactant from the water of a drain containing these components, an anode and a cathode are installed in an anodic chamber 15 and a cathodic chamber 17 respectively which are separated by a porous diaphragm 18, and the drain is sent to the anodic chamber 15, in a diaphragm electrolytic step 13, in which a direct voltage is applied to a space between the anode and the cathode. The drain is electrolytically treated and part of an anodic treating liquid is allowed to pass through the diaphragm to a drained from the cathodic chamber 17, while the remainder of the anodic treating liquid is drained from the anodic chamber 15. Further, this liquid from the anodic chamber 15 is introduced into a filled layer 25 in which an adhesive material is packed to allow the liquid to come into contact with the adhesive material. After that, the liquid is guided into an oil/water separation step 2 to perform the separation process. The diaphragm electrolytic step 13 should preferably be operated in such a manner that the polarity of the electrode is alternately converted per specified treating time and thereby, the anodic chamber 15 is switched to the cathotic chamber 17 and the cathodic chamber 17 to the anodic chamber 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to oil-water separation of waste water containing an emulsified oil, and more particularly to oil-water separation by subjecting a water-based cleaning liquid, a water-soluble cutting oil and a coolant waste liquid simultaneously containing a surfactant and an oil to a diaphragm. Method and apparatus.

[0002]

2. Description of the Related Art Along with the revision of the London Convention on the Waste Disposal of Oceans, water-soluble cutting oil and coolant waste liquids, which have been largely disposed of by oceans, cannot be disposed of in the ocean. Development of effective land treatment technology is an urgent issue. In addition, since chlorofluorocarbon and trichloroethane, which have been widely used as industrial cleaning agents, have been confirmed to be ozone depleting substances, their production was discontinued by 1995 under an international agreement. Under such circumstances, there is an urgent need to develop a substitute for CFCs and trichloroethane, and aqueous detergents containing surfactants and alkalis as main components, semi-aqueous detergents in which water is mixed with organic solvents such as alcohols and glycol ethers, and Non-aqueous cleaning agents represented by hydrocarbon solvents are becoming mainstream.

[0003] However, in the case of non-aqueous cleaning agents, the running cost is high because they are washed with the cleaning agents themselves, and most of them are flammable substances. Or they have the disadvantage that they cannot be made larger. On the other hand, in the case of water-based and semi-water-based systems, especially in the case of water-based systems, a large amount of water is used to dilute the cleaning agent, so that the running cost is low. Relatively cheap. However, the use of a large amount of water at the same time makes a water treatment system capable of coping with the oil-water separation of the washing liquid and the drainage treatment of the rinse water an indispensable component of the washing system. For example, when a work (a body to be cleaned) is cleaned using an aqueous cleaning agent, dirt such as oil from the work gradually accumulates in the cleaning liquid with the cleaning, and the cleaning power of the cleaning liquid is reduced.
Naturally, in order to extend the service life of the cleaning liquid while maintaining the cleaning power of the cleaning liquid, it is necessary to constantly remove dirt such as oil from the cleaning liquid.

Conventionally, oil-water separation methods for water-based cleaning liquids include emulsification breaking / floating separation methods using chemicals such as emulsion breakers, electrostatic separation methods, coalescer methods for promoting coalescence and coarsening of oil particles, and microfiltration. Processing by a membrane separation method or the like has been performed using a membrane or an ultrafiltration membrane. However, each of these conventional techniques has a problem. For example, in the emulsification breaking / floating separation method using an emulsion breaker, there is a problem that the washing liquid after oil-water separation loses washing power and cannot be reused. Further, in the electrostatic separation method or the coalescer method, when the oil component in the cleaning liquid exists as fine emulsion particles, it is difficult to obtain the oil-water separation effect. In addition, the microfiltration membrane and the ultrafiltration method have a problem that the detergent component is removed together with the oil, and a problem that the apparatus is expensive.

[0005] A water-based detergent generally comprises a surfactant which has a detergency as a main component, and other organic and inorganic builders such as a rust preventive, an antifoaming agent, and an alkali component. Nonionic surfactants and anionic surfactants can be used as the surfactant that acts as the detergency. Nonionic surfactants having a cloud point temperature in the range of 30 to 60 ° C. from the viewpoint of detergency. Activators are often used. In use, the aqueous cleaning agent is diluted with water to a predetermined concentration and used as an aqueous cleaning solution. Nonionic surfactants dissolve in water below the cloud point temperature and exhibit surface activity, but above the cloud point temperature, hydrophilic groups dehydrate and the molecules associate to lose surface activity and the liquid temperature decreases. If it becomes higher, it precipitates in a floc or liquid form. Conversely, when the liquid temperature falls below the cloud point temperature, the hydrophilic group of the surfactant, which has become insoluble once, hydrates and is dissolved again in water to recover the surface activity.

[0006] Therefore, in the oil-water separation of the aqueous cleaning liquid mainly containing a nonionic surfactant, if the aqueous cleaning liquid is heated to a temperature higher than its cloud point, the surfactant loses surface activity. The oil can float and separate. However, in the presence of oil, the surfactant does not precipitate due to the interaction with the oil, but instead floats with the oil, and in some cases the original oil-water separation purpose of discharging only the oil outside the system cannot be achieved. Many. Further, the present inventors have previously prepared an aqueous detergent obtained by mixing a nonionic surfactant having a cloud point temperature of 20 to 40 ° C. with a nonionic surfactant having a cloud point temperature of 40 to 70 ° C. A water-based cleaning liquid that can float and separate dirt such as oil in the cleaning liquid by simply heating the cleaning liquid containing dirt such as oil to a temperature higher than the cloud point temperature of the cleaning agent, and an oil-based water used in cleaning. We proposed a separation method and developed a technology that can achieve excellent oil-water separation even under the conditions where the oil component coexists.

[0007] This technique, however, exhibits excellent functions with respect to a washing liquid containing a water-insoluble oil and a demulsifying type among water-insoluble oils. It could not be applied to a washing liquid containing an emulsified water-insoluble oil containing an active substance. Oils used in the field of machining metal parts include water-soluble cutting oils and water-soluble oils represented by coolants, and water-insoluble oils represented by press working oils and rolling oils. Further, among the water-insoluble oils, there are an emulsifying type and a demulsifying type. The water-soluble oil represented by the water-soluble cutting oil and the coolant contains a large amount of anionic surfactants such as sodium alkyl sulfonate, and also prevents anionic surfactants such as calcium sulfonate in water-insoluble oils. Some rust agents are included in large quantities. As described above, the oil-water separation method of the heating system applied to the water-based cleaning agent developed by the inventors and the cleaning agent cannot be applied to the oil containing a large amount of an anionic surfactant.

[0008] In order to solve these problems, the present inventors have previously proposed Japanese Patent Application No. 8-156384.
FIG. 2 shows a schematic configuration diagram of the device. In FIG. 2, the treated water from the anode chamber 15 is directly connected to the anodized liquid / water separation tank 2, and the anode 14 and the cathode 16 are fixed. By the way, the above technique has the following problems. (A) In the above technique, it is necessary to lower the pH of the anodizing solution to a pH at which oil-water separation occurs, that is, a pH value at which the emulsified oil component is sufficiently demulsified. If the oil-water separation can be performed at a higher pH, the oil-water separation ability can be improved. (B) the membrane and the electrode surface are gradually contaminated with the treatment,
As a result, the amount of permeated water from the anode chamber to the cathode chamber decreases, and the electrolysis voltage for maintaining a constant electrolysis current increases. Therefore, there is a need for a means of removing diaphragm and electrode contamination and restoring permeate flow and voltage.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the above-mentioned technology, enables oil-water separation at a higher pH, and removes membrane and electrode contamination by a simple means, and removes permeation. An object of the present invention is to provide a method and an apparatus for separating oil-water from emulsified oil-containing wastewater, which can recover the flow rate and the voltage.

[0010]

In order to solve the above-mentioned problems, the present invention provides a method of separating oil-water wastewater containing a surfactant and an oil emulsified by the action of the surfactant. An anode and a cathode are respectively provided in the anode chamber and the cathode chamber partitioned by, and the wastewater is sent to the anode chamber of a diaphragm electrolysis process in which a DC voltage is applied between the anode and the cathode, and subjected to electrolytic treatment. After a part of the anodizing solution is discharged from the cathode chamber through the diaphragm, and the remaining anodizing solution is discharged from the anode chamber, introduced into the packed layer filled with the adhering material, and brought into contact with the adhering material. , To an oil / water separation step to separate the oil / water. In the oil-water separation method,
In the diaphragm electrolysis step, the polarity of the electrode is preferably alternately changed every predetermined processing time, and the anode chamber is preferably switched to the cathode chamber and the cathode chamber is switched to the anode chamber.

Further, according to the present invention, in an oil-water separation apparatus for wastewater containing a surfactant and an oil component emulsified by the action of the surfactant, the anode chamber and the cathode chamber separated by a porous diaphragm are respectively provided with an anode and a cathode. A membrane electrolytic cell provided with a cathode, a packed tower filled with an adhering material, and an anodizing liquid oil / water separation tank are provided, and the wastewater is introduced into the anodizing liquid oil / water separation tank, and from the bottom of the oil / water separation tank. The liquid is sent to the anode chamber of the diaphragm electrolyzer, a part of the anodizing solution in the anode chamber is discharged from the cathode chamber through the diaphragm, and the remaining anodizing liquid flows upward from the anode chamber to the packed tower. After being brought into contact with the adhesion material by being guided by the above, each was connected so as to circulate in the anodizing liquid oil / water separation tank. In the device, the diaphragm cell can alternately change the polarity of the electrode, and simultaneously switch the anode chamber to the cathode chamber and the cathode chamber to the anode chamber, respectively, and switch the connection piping to the anode chamber and the cathode chamber. Good to do.

[0012]

Next, the present invention will be described in detail.
In the oil-water separation method of the present invention, the pH of the anodizing solution can be lowered to the pKa (acid dissociation index) value of the anionic surfactant in water by the diaphragm electrolysis in the anode chamber, and water from the anode chamber to the cathode chamber can be reduced. The oil content is concentrated by the anode compartment and the oil-water separation by the electroosmosis effect and the filtration effect by the transmembrane pressure difference between the anode compartment and the cathode compartment (0 to 0.2 MPa).
The concentration ratio is set to 0.5 to 5 times. Here, electroosmosis is
At the time of electrolysis, in particular, as cations such as Na ⁺ are electrophoresed from the anode chamber to the cathode chamber, water is separated into the membrane (in the present invention, a microfiltration membrane having an average pore diameter of 0.1 to 3.0 μm is used).
To penetrate from the anode compartment to the cathode compartment. Also, by mixing sodium phosphate or sodium tripolyphosphate and sodium sulfate, etc., in the wastewater to be treated as 0-30 mM electrolytic aids, respectively, scales on the cathode surface and the diaphragm due to hardness components such as calcium, magnesium and barium. It is possible to prevent adhesion and increase the conductivity of the treated water.

Further, in the oil / water separation apparatus of the present invention, in addition to the above, by circulating the anodizing solution between the anode chamber and the anodizing solution oil / water separation tank, the anionic surfactant accompanying the pH decrease is reduced. Prevention of clogging of the diaphragm by allowing the insolubilization reaction to take place in the anodizing liquid oil / water separation tank instead of in the anode chamber and increasing the flow rate (0.1 to 0.5 m / sec) on the anode chamber side membrane surface. By aiming, and maximizing the oil separation rate of one pass to the oil-water separator of the treated water,
Oil separation capacity per unit electrolysis current can be increased. Further, by providing an electric heater in the anodizing liquid oil / water separation tank, the oil separation efficiency can be increased by heating the processing liquid above the cloud point temperature of the nonionic surfactant,
By introducing the catholyte treatment liquid discharged from the cathode chamber into the catholyte treatment liquid oil / water separation tank, the oil component that has passed through the diaphragm is floated and separated, whereby the oil / water separation efficiency can be increased.

In the present invention, a packed bed as a coalescer is provided between the membrane electrolytic cell and the anodizing liquid oil / water separation tank. In the invention of the prior application, the emulsified oil-containing wastewater to be treated is introduced into an anodizing liquid oil / water separation tank, and is fed from the bottom of the oil / water separation tank to the anode chamber of the diaphragm electrolysis tank. Is discharged from the cathode chamber through the diaphragm, and the remainder is circulated from the anode chamber to the anodizing liquid oil / water separation tank.In the present invention, the anodizing liquid is discharged from the anode chamber to the anodizing liquid oil / water separation tank. Before circulating, the treatment liquid was guided to the packed bed in an upward flow, and was brought into contact with the adhering material filled in the packed bed. By once adhering the oil particles in the treatment liquid to the adhering material, the probability of collision between the oil particles increases, so that coalescence and coarsening of the oil particles are promoted, and the oil-water separation effect by a so-called coalescer is obtained. . As described above, as a result of synergistic effects of the oil-water separation by the membrane electrolysis and the coalescer, the oil-water separation pH is increased, and the oil-water separation performance is improved.

Here, the filling layer used as a coalescer may have any shape such as a cylindrical shape or a square shape, and any material may be used as long as the material to be filled is chemically stable and has a large specific surface area. Aggregates of fibers are preferred. For example, the particulate adhesive includes silica sand, zeolite, kaolin, and the like, and the fibrous adhesive includes slag wool and synthetic fibers. The larger the volume of the packed bed, the longer the contact time and the higher the effect of the coalescer, but the superficial velocity (SV, unit: h ^-1 ) of the processing liquid passing through the packed bed is 20 to
A range of 200 h ^-1 is sufficient. Furthermore, once the oil is adhered to the adhering material, the density of the oil particles in the adhering material increases, and the contact efficiency between the oil and the treatment liquid increases.
As a result, hydrophobic organic substances in the processing liquid, for example, nonionic surfactants and anionic surfactants that cannot be dissociated due to the acidity of the processing liquid are discharged to the oil component and removed together with the oil component. The effect is also obtained.

Further, in the present invention, the polarity of the electrode is alternately changed every fixed processing time, that is, the anode is switched to the cathode and the cathode is switched to the anode every fixed processing time, and at the same time, the connection between the anode chamber and the cathode chamber is made. Change the piping to be used. Normal,
Since the anode compartment is acidic, some anionic surfactants become insoluble, and the insoluble substance and the emulsified oil particles may adhere to the surfaces of the electrode and the diaphragm to cause contamination. On the other hand, since the cathode compartment is alkaline, insoluble alkaline earth metal hydroxide may be generated and adhere to the surface of the electrode and the diaphragm. In the present invention, if the polarity is changed after a certain processing time after the contamination has progressed to some extent, the acidic anode chamber becomes a cathode chamber and becomes alkaline, and the alkaline cathode chamber becomes an anode chamber and becomes acidic. The respective insoluble contaminants are dissolved and removed, and the permeate flow rate and electrolysis voltage of the diaphragm are restored. The shorter the interval between polarity conversions, the greater the pollutant removal effect. However, frequent polarity conversions have the disadvantage of shortening the electrode life. The polarity conversion interval may be determined within a range of 4 to 72 hours depending on the contaminant load (the concentration of the anionic activator, the concentration of the oil component, the concentration of the alkaline earth metal, etc.) of the liquid to be treated.

In the present invention, the surfactant contained in the waste water includes anionic surfactants such as sodium organic carboxylate, organic sodium sulfonate and organic sodium sulfate, and polyoxyethylene alkyl phenyl ether type, polyoxyethylene Alkyl ether type, polyethylene glycol type, sorbitan fatty acid ester type, polyoxyethylene sorbitan fatty acid ester type and pluronic type nonionic surfactants, and inorganic builder contained in wastewater include various sodium phosphates, Various sodium silicate, various sodium borate, and the like. The wastewater to be treated preferably has an alkalinity in the range of 0.1 to 10.0. Here, the alkalinity means 10 ml of treated water 0.1 N
It is the number of ml of 0.1N hydrochloric acid dropped when titrating with hydrochloric acid to the end point pH of 4.8.

According to the present invention, the wastewater containing the emulsified oil is passed through the anode chamber in the membrane electrolysis step, and water is electrolyzed according to the following formula to generate hydrogen ions in the medium in the anode chamber. Let it. That is, the treated water can be made acidic by generating hydrogen ions such as H ₂ O → 1 / 2O ₂ + 2H ⁺ + 2e ⁻ . By generating hydrogen ions in the treated water, the pH of the treated water is determined from the pKa value of an anionic surfactant present in the treated water, for example, sodium alkyl sulfonate.
The to the alkylsulfonic acid anion reacts as shown in the following formula ^{_{low, R-SO 3 - + H}} + → R-SO 3 surfactant properties ready to a hydrogen is bound to the anion group such as H is lost Become insoluble. Thus, it is possible to suppress the interference of the anionic surfactant and the anionic surfactant with respect to the oil-water separation of the present invention. The acidity to be adjusted may be pH 8 or less and pH 1 to 7, but generally pH 3 to 7 is sufficient.

Further, according to the present invention, the oil water is concentrated by the electroosmotic effect. That is, as cations such as Na ⁺ are electrophoresed from the anode compartment to the cathode compartment, water penetrates the diaphragm (average pore diameter of 3 μ or less) and penetrates from the anode compartment to the cathode compartment. Oil water in the treated water of the oil / water separation tank is concentrated. The treated water whose pH has been adjusted through the anode chamber is sent to an oil-water separation tank, and the temperature of the treated water is heated to a predetermined appropriate temperature equal to or higher than the cloud point temperature of the nonionic surfactant contained therein. The treated water from which the oil has been separated and from which the oil has been removed is circulated to the anode chamber in the membrane electrolysis step. In the diaphragm electrolytic cell used in the present invention, the electrolytic cell is divided into an anode chamber and a cathode chamber by a porous diaphragm, and an anode and a cathode are provided in the anode chamber and the cathode chamber, respectively. As the porous diaphragm, an MF membrane which is usually an organic microfiltration membrane (average pore diameter: 0.1 to 3.0 μ) is used. The electrode is not particularly limited as long as it is an insoluble electrode, but an electrode obtained by plating platinum on a substrate such as titanium is preferable for the anode and the cathode, and a cheaper ferrite or stainless steel electrode can be used for the cathode. .

Next, the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration diagram of an example of the oil-water separation device of the present invention. In FIG. 1, wastewater containing oil emulsified from a receiving tank 1 is introduced into an anodizing liquid oil / water separation tank 2 from a treated water inlet 5. The anodizing liquid / water separation tank 2 is provided with an electric heater 3 and an air vent valve 4.
Chamber 1 in which the anode 14 of the diaphragm cell 13 is provided
5 In the diaphragm electrolyzer 13, an anode chamber 15 and a cathode chamber 17 are divided by a diaphragm 18, an anode 14 and a cathode 16 are provided in each chamber, and a predetermined DC current is applied from a power supply 19. In the treated water supplied to the anode chamber 15, an anionic surfactant such as sodium alkyl sulfonate loses surface activity due to hydrogen ions generated by electrolysis of the water.

The acidified treated water is introduced from the anode chamber 15 of the diaphragm electrolyzer 13 through the packed tower 25 filled with the adhering material into the anodized liquid / water separation tank 2 through the inlet 7.
In the oil-water separation tank 2, the non-ionic surfactant is heated by the electric heater 3 to a temperature higher than the cloud point temperature of the nonionic surfactant. The cleaning liquid sent to the anodizing liquid oil / water separation tank 2 can be floated and separated only by heating to a temperature range of 50 to 80 ° C, preferably 60 to 70 ° C. The washing liquid is retained in the oil / water separation tank 2 so as to have a residence time of not more than 20 minutes, and the separated oil is continuously or intermittently separated and discharged out of the system. Oil and water are separated while being circulated in the chamber 15.

On the other hand, the treated water flowing from the anode chamber 15 through the diaphragm 18 into the cathode chamber 17 is returned from the cathode chamber to the receiving tank 1 through the valve 29. When such a treatment is performed for a certain period, the diaphragm and the electrode surface gradually contaminate, the amount of permeated water from the anode chamber to the cathode chamber decreases, and the electrolysis voltage for maintaining a certain electrolysis current increases. In such a case, the switching plate 32 connected to the power supply 19 converts the anode and the cathode of the voltage applied to the electrolytic cell 13, and converts the anode chamber 15 into the cathode chamber and the cathode chamber 17 into the anode chamber. And valves 26 and 2
Switching is performed by closing 8, 31 and opening valves 27, 29, 30. As a result, contaminants attached to the diaphragm and the electrode surface are removed, and the amount of permeated water and the electrolytic current are restored.

[0023]

The present invention will be described below in more detail with reference to examples. Example 1 An oil / water separator manufactured according to FIG. 1 was used for the test. In this apparatus, the diaphragm electrolytic cell was a sealed rectangular type made of polypropylene resin, the anode and the cathode were the same platinum-plated titanium electrodes, and the electrode area was 0.1 m ² . The porous membrane used was an organic synthesis microfiltration membrane (MF membrane) having a nominal pore size of 0.5 μm. Here, a filter cartridge (manufactured by Advantech Co., Ltd.) with a nominal filtration accuracy of 5 μm (thread-wound type and thread material is PPS) was used as the packed bed, and the superficial velocity (SV) was 100 h ⁻¹ . The internal volume of the anodizing liquid oil / water separation tank was 36 liters.

In the present embodiment, as the emulsified oil-containing wastewater to be treated, warm water washing water of W1 type water-soluble cutting oil is assumed.
Oil-water separation of the washing water was continuously performed. First, city water to which 0.02% of sodium tripolyphosphate was added was injected into the washing tank 1 and the anodized liquid oil / water separation tank 2 as washing water.
The amount of the injection washing water was 240 liters in total. The pH of the washing water was 8.9, and the temperature was kept at 50 ° C. by an electric heater installed in the washing tank 1. Subsequently, continuous injection of a water-soluble cutting oil manufactured by a certain company, W Type 1 No. 1 into the cleaning tank 1 was started, and the injection flow rate was set to 1.3 ml / min. The washing water in the washing tank 1 was stirred with a stirrer to disperse the water-soluble cutting oil. The cleaning water is circulated by the pump 9 at a flow rate of 8 liters / min between the anode chamber 15 of the electrolytic cell 13, the packed bed 25, and the anodized liquid oil / water separation tank 2 while maintaining a constant current of 25 amperes. Electrolysis was performed. At the start of electrolysis, the electrode 14 is an anode,
The electrode 16 is used as a cathode, the bulbs 26, 28 and 31 are fully opened,
The valves 27, 29 and 30 were fully closed. The flow rate of the cathode treatment liquid returned to the cleaning tank 1 is 0.42 liter / min, and the pH is 1
It had been around 1.0.

The pH of the anodizing solution gradually decreased from the start of electrolysis, and reached 6.0 after one hour. At this point, the valve 12 is operated and the flow rate is 0.45 liter /
Minutes, the anodizing solution was continuously returned to the washing tank. Thereafter, the pH of the anodizing solution was stably changing around 6.0. The polarity of the electrode was changed every 12 hours. In the first operation of the polarity conversion, the output polarity of the DC power supply is switched, and at the same time, the electrode 14 is used as the cathode, the electrode 16 is used as the anode, the valves 26, 28, and 31 are fully closed, and the valves 27 and
29 and 30 were fully opened. In the subsequent polarity conversion, the reverse operation of the previous operation was repeated. The oil separated by flotation was discharged from the oil-water separation tank 2 every several hours in the continuous test, and the oil concentration and TOC (total organic carbon concentration) of the washing water in the washing tank 1 were analyzed, and the electrolysis voltage was recorded. FIGS. 3A to 3C show changes over time in the oil concentration (a), TOC (b), and electrolysis voltage (c) of the washing water. From FIG. 3, it can be said that the oil-water separation of the water-soluble cutting oil cleaning water according to the present invention was effective and the electrolytic voltage was also stably changed.

COMPARATIVE EXAMPLE 1 In order to clarify the operation of the present invention, as a comparative example, oil and water were used under the same apparatus and conditions as in Example 1 except that the packed bed 25 was not provided and the polarity was not changed. A separation test was performed. The test data of the comparative example is also shown in FIG. As can be seen in FIG. 3, oil-water separation at a relatively high pH (here, pH 6.0) was not effective without a packed bed. In order to effectively perform the oil / water separation of the washing water without disposing the packed bed 25, it was necessary to reduce the flow rate returned to the washing tank and reduce the pH of the anodizing solution to 4.5. The electrolysis voltage gradually increased from around 30 volts at the start of electrolysis, and reached 95 volts after 48 hours. At this time, the test was stopped because the temperature of the cathode treatment solution rose to 85 ° C. and approached the heat-resistant limit temperature of the electrolytic cell.

[0027]

According to the present invention, the following effects can be obtained. a) By disposing a packed layer as a coalescer between the anode chamber of the diaphragm electrolysis tank and the anodized liquid oil / water separation tank, the oil / water separation pH can be raised and the oil / water separation performance can be improved. b) Because the contact efficiency between the oil and the treatment liquid in the packed bed is high,
It is possible to extract a hydrophobic organic substance in the treatment liquid into an oil component and remove it together with the oil component from the system. c) By alternately changing the polarity of the electrode every certain processing time, the permeation flow rate from the anode chamber to the cathode chamber and the electrolysis voltage for maintaining a certain electrolysis current are maintained for a long time within a certain range. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one example of an oil-water separation device of the present invention.

FIG. 2 is a schematic configuration diagram showing an oil-water separation device of the prior application.

FIG. 3 shows oil concentration (a) according to treatment time, TOC
(B) Graph showing the change in electrolysis voltage (c).

[Explanation of symbols]

1: receiving tank, 2: anodizing liquid oil / water separation tank, 3: electric heater, 4: air release valve, 5: treated water inlet, 6: anodizing liquid outlet, 7: anodizing liquid inlet, 8: oil storage Tank, 9: liquid feed pump, 10: pressure gauge, 11: pressure regulating valve, 12: anodizing liquid return valve, 13: diaphragm electrolytic cell, 14: anode: 1
5: anode compartment, 16: cathode, 17: cathode compartment, 18: diaphragm,
19: DC power supply, 20: Cathode treatment oil / water separation tank, 21:
Cathode treatment liquid inlet, 22: Cathode treatment liquid outlet, 23: Air release valve, 24: Prefilter, 25: Packing tower, 26-3
1: Valve, 32: Switching plate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C02F 1/46 CCK C02F 1/46 CCK 1/469 103

Claims (4)

[Claims] 1. An oil-water separation method for wastewater containing a surfactant and an oil emulsified by the action of the surfactant, wherein an anode and a cathode are provided in an anode chamber and a cathode chamber partitioned by a porous membrane, respectively. The wastewater is fed to the anode chamber of the diaphragm electrolysis step in which a DC voltage is applied between the anode and the cathode, and is subjected to electrolytic treatment, and a part of the anodized solution is passed through the diaphragm to pass from the cathode chamber. The emulsified oil component is discharged by discharging the remaining anodized solution from the anode chamber, introducing the mixture into the packed bed filled with the adhering material, and bringing the adhering material into contact with the adhering material. Oil-water separation method for contained wastewater. 2. An oil / water separator for waste water containing a surfactant and an oil component emulsified by the action of the surfactant, wherein an anode and a cathode are provided in an anode chamber and a cathode chamber partitioned by a porous membrane, respectively. A diaphragm electrolytic cell, a packed tower filled with an adhering material, and an anodizing liquid oil / water separation tank are provided, and the wastewater is introduced into the anodizing liquid oil / water separation tank, and the diaphragm electrolytic cell is introduced from the bottom of the oil / water separation tank. To the anode chamber, a part of the anodizing solution in the anode chamber passes through the diaphragm and is discharged from the cathode chamber, and the remaining anodizing solution is guided upward from the anode chamber to the packed tower and adhered. An oil / water separator for emulsified oil-containing wastewater, wherein each of them is connected so as to circulate in the anodized liquid / water separator tank after contact with the material. 3. The membrane electrolysis process according to claim 1, wherein the polarity of the electrode is alternately changed every predetermined processing time, and the anode chamber is switched to the cathode chamber and the cathode chamber is switched to the anode chamber. Oil-water separation method for emulsified oil-containing wastewater. 4. The diaphragm electrolyzer can alternately change the polarity of the electrodes, switch the anode chamber to the cathode chamber, switch the cathode chamber to the anode chamber, and simultaneously switch the connection pipe between the anode chamber and the cathode chamber. 3. The oil / water separator for wastewater containing emulsified oil components according to claim 2, wherein the oil / water separator is constituted.