JP2006021152A - Oily water separating method and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for separating oil from water by an electrolytic flotation method using electrolysis, in which scum formed by combining an eluted metal with oil in the liquid to be treated is recovered by floating the scum in the upper part of the liquid to be treated without precipitating the scum at the bottom of the liquid to be treated so that the stable performance of this apparatus can be kept while keeping the oil concentration in the treated liquid to be discharged below a preset value even if a treatment tank is not cleaned. <P>SOLUTION: When oily water separation is performed by electrolyzing the liquid which is to be treated and is housed in a separation tank 13 by using at least a pair of positive/negative electrodes 15, minute air bubbles are supplied slowly to each of electrodes from a nozzle 33 from the lateral side of each of electrodes 15 so that minute air bubbles surround each of electrodes when the liquid to be treated is electrolyzed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an oil-water separation method and an apparatus therefor, and in particular, an oil-water separation method in which oil contained in a liquid to be treated is levitated by electrolyzing a liquid to be treated stored in a treatment tank, and water and oil are separated. It relates to the device.

  Conventionally, as an oil-water separation technique, there is an electrolytic levitation method using electrolysis (hereinafter abbreviated as electrolysis) as described in Patent Document 1 below.

  In this electrolytic levitation method, the liquid to be treated is electrolyzed in the treatment tank, and the metal content of the electrode is eluted into the liquid to be treated by electrolysis, and this eluate and the oil in the liquid to be treated are combined to form a scum. The scum having a specific gravity smaller than that of the water floats on the top of the liquid to be treated, and bubbles generated by electrolysis help the scum rise, and conversely, the scum having a specific gravity larger than that of the water settles on the bottom of the treatment tank, Water and oil in the liquid to be treated are separated.

  And the to-be-processed liquid after oil-water separation, ie, the processed liquid, is suitably discharged from the processing tank.

Japanese Patent Laid-Open No. 2001-300542

  In the above prior art, the floating scum can be collected by a scraping device or the like, but the precipitated scum could not be collected unless the liquid put into the treatment tank is removed.

  Precipitated scum has good fluidity due to a slight difference in specific gravity with water, and when the amount of precipitation increases, it becomes easier to mix in the treated liquid, and the concentration of oil in the treated liquid that is discharged exceeds the set value. Therefore, it is necessary to periodically clean the inside of the treatment tank every short period.

  Therefore, an object of the present invention is to provide a scum that is a metal eluate associated with the oil content of the liquid to be treated without precipitating on the bottom of the liquid to be treated, even in an oil / water separator using electrolytic levitation using electrolysis. An object of the present invention is to provide an oil / water separator that can be recovered by floating on the upper part of the processing liquid, and can maintain a stable performance by keeping the oil concentration of the discharged processed liquid below a set value without cleaning the processing tank. .

The oil-water separation method of the present invention that achieves the above object is characterized in that in the oil-water separation method in which electrolysis is performed with at least one pair of positive and negative electrodes, the liquid to be treated contained in the treatment tank is electrolyzed. In addition, fine bubbles are gently supplied from the side of each electrode so as to surround each electrode.
In addition, the oil / water separator according to the present invention that achieves the above object is characterized in that a treatment tank that accommodates a liquid to be treated and electrolyzes the liquid to be treated is provided with at least a pair of positive and negative electrodes. In an oil / water separator having a floating oil receiver that collects scum generated and floated in the process of electrolysis, a liquid to be treated in which air is dissolved in a side wall of the treatment tank is used as a liquid to be treated in the treatment tank. A nozzle for spraying is provided.

  The arrangement of the nozzles on the side walls in the treatment tank is preferably such that the sprayed liquid to be treated proceeds in parallel with the electrode surfaces of the pair of positive and negative electrodes facing each other.

  Moreover, it is good to provide the deceleration part which decelerates the to-be-processed liquid injection speed from a nozzle in installation of the nozzle to the side wall part in a processing tank.

  Further, in order for the fine bubbles to surround the electrodes, the lowermost part of each of the positive and negative electrodes in the processing tank is preferably in the liquid to be processed from the nozzle.

  ADVANTAGE OF THE INVENTION According to this invention, the to-be-processed liquid jet flow from the nozzle which flows slowly in a horizontal direction with respect to the to-be-processed liquid in a processing tank can be formed. When the liquid to be treated is ejected from the nozzle, the air that has been decompressed and dissolved becomes fine bubbles, and slowly moves so as to surround the electrode with the fine bubbles together with the liquid to be treated that flows in the horizontal direction. Will stop.

  On the other hand, the scum in which the oil component and the metal eluate are combined has almost no kinetic energy when it is located in the vicinity of the electrode and is in the state of whether or not to start flying or sinking.

  If there is a scum that has almost no kinetic energy in a state in which the fine bubbles stop moving in the lateral direction or start to rise, the scum and the bubbles are likely to merge because they are close to each other.

  Thus, most scum rises with the bubbles and can be recovered from the floating oil receiver. If there is no scum that settles, not only will the cleaning of the treatment tank be almost eliminated, but there will also be no scum discharged in the treated liquid, and the oil concentration of the treated liquid to be discharged will be kept below the set value. High performance oil / water separation.

  The oil / water separator according to the embodiment of the present invention shown in FIG. 1 will be described below.

  The oil-water separator shown in FIG. 1 is used as an example for treating drain discharged from an air compressor.

  In FIG. 1, a treatment tank 11 includes a separation treatment tank (separation part) 13 for storing a liquid to be treated and separating oil and water in the tank, and a floating oil receiving part 14 for recovering the oil component floating and separated by the separation part 13. , And a plurality of pairs of positive and negative electrodes 15 are arranged inside the separating portion 13.

  A pipe 30 attached to the bottom of the separation unit 13 in the processing tank 11 is connected to a circulation pump 31 via a valve 36, and an outlet side pipe 37 of the circulation pump 31 is connected to a nozzle 33.

  The nozzle 33 is connected to the lower part of the side wall of the separation unit 13 via a speed reduction pipe 38, and the discharge port of the nozzle 33 opens laterally into the separation unit 13, passing through the circulation pump 31 from the pipe 30 and the nozzle 33. The path leading to (1) constitutes a circulation piping system for the liquid to be treated that circulates outside the tank.

  As an example of the circulation pump 31, a vortex pump is used. Although not shown, a gauge for measuring the pressure (water pressure) of the liquid to be treated is provided at the outlet of the circulation pump 31.

  Each electrode 15 has a lower height L2 when viewed from the bottom of the separation portion 13 is higher than a lower height L1 of the speed reduction tube 38 (L1 <L2), and is further ejected from the nozzle 33 into the separation portion 13. The flow direction of the liquid to be processed is provided so as to be parallel to the surface of each electrode 15.

  An air supply pipe 35 that supplies air via a valve 34 and a supply pipe 23 that has a supply pump 21 and a valve 22 and constitutes a supply pipe system for untreated liquid are connected to the pipe 30. .

  A discharge pipe 41 that discharges the processed liquid from the separation section 13 is provided above the separation section 13, and the discharge pipe 41 is lifted from a connection portion (tube seat) with the side wall of the separation section 13 and downstream thereof. Is piped to a position lower than the connecting portion with the separating portion 13 and has a valve 42 in the middle thereof. The highest position of the discharge pipe 41 is set lower than the highest position of the shielding plate 12 of the separating portion 13 to have a positional difference D1.

  Therefore, when supplying and storing the liquid to be processed in the separation unit 13, if the valve 42 is opened, the liquid to be processed flows out from the discharge pipe 41, and the liquid surface H 1 to be processed in the separation unit 13 is discharged from the discharge pipe. If the valve 42 is closed and the liquid to be processed is supplied into the separation unit 13, the liquid surface H 1 to be processed rises above the highest level of the discharge pipe 41. 41 has a function of discharging the liquid to be treated and adjusting the water level by opening and closing the valve 42. A floating oil liquid surface H2 of floating oil (scum) that has been raised by oil-water separation is formed above the liquid surface H1 to be treated.

  In the tube seat portion of the discharge pipe 41, the processing target liquid flowing into the discharge pipe 41 from the separation section 13 is mixed with fine bubbles, metal eluate, and oil particles (oil) that are rising in the separation section 13. A partition plate 16 to prevent is provided, and a pocket-like suction portion 17 is formed.

  The highest position of the partition plate 16 is lower than the highest position of the discharge pipe 41 to have a positional difference D2, and is higher than the pipe seat portion of the discharge pipe 41 to have a positional difference D3. If the lowering speed of the liquid to be treated in the pocket-like suction part 17 determined by the outflow amount of the liquid to be treated in the discharge pipe 41 and the inlet area of the pocket-like suction part 17 is slower than the rising speed of the bubbles in the separation part 13, the separation part. Fine bubbles, metal eluate and oil particles (oil) rising up 13 do not flow into the pocket-like suction part 17 and enter the discharge pipe 41.

  An oil discharge pipe 51 for discharging oil in the form of a scum S is provided at the bottom of the floating oil receiver 14.

  Although not shown in the drawing, piping that leads to the outside is provided at the bottom of the separation tank 13 and a valve is provided in the middle thereof, and these are used when it is necessary to discharge the liquid inside the separation unit 13.

  Alternatively, the supply pipe 23 may be connected to the lower part of the separation unit 13 to supply the untreated liquid to the separation unit 13.

  The separation unit 13 is provided with a temperature measuring device 61 so that the liquid temperature of the separation unit 13 can be measured. Although not shown, a temperature measuring device may be installed in the pipe 37 from the pipe 30 to the nozzle 33 via the circulation pump 31 to measure the liquid temperature of the separation unit 13.

Next, the operation will be described.
First, the continuous processing operation performed at a time when the absolute humidity is high will be described.

  As a preparation, the valve 42 is opened to fill the separation unit 13 with clean water or a treated liquid to be treated. When the liquid surface H1 to be treated is at the highest level of the discharge pipe 41, the circulation pump 31 is operated. At this time, the valve 22 is closed and the supply pump 21 is stopped.

  The valves 34 and 36 are in an open state, and fresh water or processed liquid to be processed flows through the pipe 30, whereby the air supply pipe 35 side becomes negative pressure, and dissolution air flows from the air supply pipe 35. The circulation pump 31 sufficiently agitates and pressurizes the inflowing air and the circulating liquid to be processed, so that the inflowing air is dissolved in the circulating liquid to be processed. The liquid to be processed and the dissolved air pressurized by the circulation pump 31 are decompressed by being discharged from the nozzle 33 into the liquid to be processed in the speed reduction pipe 38, and the air dissolved in the water becomes bubbles. The bubbles are decelerated in the decelerating tube 38 and sent to the separation unit 13.

  The amount of air dissolved in the liquid to be processed by pressurization by the circulation pump 31 follows the Henry's law under pressure, and the pressure applied to the fresh water or the liquid to be processed flowing through the pipe 30 and the pipe 30. The amount of dissolved air increases in proportion to the flow rate flowing through the. Further, the lower the temperature of the fresh water flowing through the pipe 30 or the processed liquid to be processed, the more air is dissolved. In actual operation, the operation is performed so that the pressure and flow rate are constant. When operated in this manner, the power of the circulation pump 31 becomes heat and is transmitted to the fresh water or the liquid to be processed flowing through the pipe 30, the liquid temperature rises, and the amount of dissolved air decreases.

  For this reason, the relationship between the flow rate of the liquid to be processed in the pipes 30 and 37, the liquid temperature of the liquid to be processed, the amount of pressurization by the circulation pump 31 and the amount of dissolved air is obtained in advance. The operation is performed by adjusting the amount of dissolving air flowing in from the air supply pipe 35 with the valve 34 so that the amount of air bubbles in the processing tank 11 rises almost uniformly.

  As described above, the air dissolved in the liquid to be treated is decompressed by being discharged from the nozzle 33 through the speed reduction pipe 38 and becomes bubbles, and floats in the separation unit 13. The amount of air dissolved is adjusted by the valve 34 so that fine bubbles that rise sequentially are discharged from the nozzle 33.

  A large bubble having a large diameter rises faster than a fine bubble because buoyancy works greatly. Large bubbles have a high ascent speed and high energy, so if they collide with the metal eluate from the electrode connected to the oil particles of the liquid to be treated, the oil and metal eluate are separated, reducing the oil-water separation performance. . Since it can be considered that the large bubbles are caused by the presence of air that has not been dissolved in the liquid to be treated even by pressurization of the circulation pump 31, the amount of dissolving air taken in from the air supply pipe 35 is controlled by the valve 34. Adjust so that excess air does not get in and keep large bubbles from rising continuously. Further, by providing the reduction pipe 38, the fine bubbles are sent to the separation unit 13 at a moderate speed. By slowing the feeding speed in this way, the fine bubbles in the separation unit 13 rise together and sequentially rise.

  Further, as shown in FIG. 2A, the flow direction and the surface of the electrode 15 are parallel so that the flow direction from the speed reduction pipe 38 into the separation portion 13 does not affect the rising speed of the fine bubbles. Is arranged. Then, as shown in FIG. 2 (b), the electrode 15 and the speed reduction tube 38 are viewed in the direction of the arrow in FIG. 2 (a), so that the position of the electrode 15 is inward by a distance D4 from the side wall position of the speed reduction tube 38. I have to.

  When the nozzle 33 is arranged on one side of the electrode 15 as shown in FIG. 2A, a flow is formed so that fine bubbles spread to the other side of the electrode 15.

  As shown in FIG. 3, when the nozzles 33 are arranged on both sides of the electrode 15, the flow may be such that fine bubbles ejected from each nozzle 33 reach the center of the electrode 15.

  Because of this arrangement, the flow is less likely to be turbulent in the separation section 13, and the electrode 15 is surrounded by fine bubbles, and the fine bubbles rise uniformly and slowly when they lose their lateral movement speed. It becomes like this.

  While maintaining this operating state, the valve 22 is opened and the supply pump 21 is driven to operate the supply system of the liquid to be processed, and the fresh water or the processed liquid to be processed is not circulated through the circulation system of the liquid to be processed. The liquid to be processed in the processing state is mixed, and the electrode 13 is energized so as to have a preset current.

  Then, oil particles are ejected from the nozzle 33 together with the fine bubbles, and the metal eluate is eluted from the electrode 15. Around the electrode 15, the fine bubbles and the oil particles have a slight horizontal movement speed, and the metal eluate descends at a low speed. The surface area is increased by the amount of the metal eluate attached. Since the surface area is increased, the scum in which the oil particles and the metal eluate are combined easily adheres to the fine bubbles, adheres to the fine bubbles, and the scum rises above the liquid surface to be treated.

  The lower part of the electrode 15 is made higher than the lower part of the decelerating pipe 38 (L2> L1), the direction in which the separation part 13 flows from the nozzle 33 and the surface of the electrode 15 are parallel, and the decelerating pipe Since the liquid to be treated is slowly ejected horizontally from 38, a gentle upward laminar flow is formed, and the generation of convection is suppressed in the separation unit 13 and turbulence hardly occurs. The oil particles and fine bubbles that flow out slowly pass between the electrodes, adhere to the metal eluate, and rise uniformly. Since the scum surely coalesces with the fine bubbles and floats, a small electrode is sufficient.

  When oil particles are jetted together with fine bubbles from the nozzle 33, the power of the supply pump 21 and the circulation pump 31 becomes heat, which is transferred to the mixed liquid to be processed, and the temperature rises, so that the amount of air that can be dissolved decreases. By decreasing, excess bubbles (large bubbles) that cannot be dissolved are generated.

  As described above, surplus bubbles have a large bubble diameter and a high ascending speed, and flow turbulence occurs in the tank, and fine bubbles adhering to oil are separated to prevent oil-water separation.

  Therefore, as described above, the relationship between the liquid temperature and the amount of dissolved air is obtained in advance, and the amount of dissolving air that flows in from the air supply pipe 35 at the liquid temperature obtained by the temperature measuring device 61 is generated in the processing tank 11 by bubbles. Since the valve 34 is readjusted so that the amount of the air will rise almost uniformly, operation is not performed, so surplus air is not generated and the oil / water separation performance is not deteriorated. In addition, a decrease in the liquid temperature due to mixing of the untreated liquid to be processed may be predicted, and the operation may be performed by fixing the flow rate at a temperature in which the amount of dissolution air is reduced in advance by the amount of decrease. However, the circulating flow rate may be reduced. A means for removing large bubbles may be provided in the pipe 37 or the speed reduction pipe 38.

  From the discharge pipe 41, the processed liquid to be processed corresponding to the unprocessed liquid supplied from the pipe 23 is sucked and discharged at a speed slower than the rising speed of the fine bubbles adhering to the scum.

  The pressure at the outlet of the circulation pump 31 is preferably about 0.3 to 0.8 MPa in consideration of reducing the required power and reducing the diameter of the fine bubbles. Considering that the amount of dissolved air is proportional to the pressure, the circulating water flow rate is 30 to 100 times the amount of untreated liquid to be treated supplied from the untreated liquid supply system, and the untreated liquid is circulated. Since it is diluted 30 to 100 times with water, the oil content of the liquid to be treated supplied to the separation unit 13 has a low concentration.

  The floating oil (a combination of scum and fine bubbles) accumulated on the upper part of the separation unit 13 temporarily closes the valve 42 provided in the middle of the discharge pipe 41 during continuous operation, and the liquid surface H1 to be treated inside the separation unit 13 and When the floating oil liquid level H2 rises and the floating oil liquid level H2 exceeds the height of the shielding plate 12, the floating oil overflows and flows down to the floating oil receiving portion 83.

  When the floating oil in the separation unit 13 decreases, the valve 42 is opened slowly, the liquid to be processed is discharged from the discharge pipe 41, the liquid level H1 to be processed is lowered, and the continuous processing is continued.

  In addition, hydrogen and oxygen are generated as bubbles from the positive and negative electrodes during electrolysis, but the bubble diameter is large and the rising speed is fast, so that scum is not collected sufficiently. To do.

  In addition, when fine bubbles are supplied together with the liquid to be processed from the bottom of the separation unit, a fast upward flow is formed around the supply port, and an early downward flow is generated around the scum. Not only is it difficult, but scum rides in convection and repeats settling and rising, making it difficult to discharge. By supplying fine bubbles slowly in the horizontal direction (substantially horizontal), convection at the separation part could be suppressed, and the scum was united with the bubbles evenly and most of the scum was discharged as floating oil.

  Furthermore, in order to suppress the occurrence of convection, a large-diameter reduction pipe is provided in the attachment portion (tube seat) of the pipe 30 to the bottom of the separation portion 13 so as to reduce the pumping speed of the liquid to be treated in the separation portion 13. It is good to.

Next, the intermittent treatment operation performed in winter when the absolute humidity is low will be described.
First, as a preparation, the circulating pump 31 is operated in a state in which the separation unit 13 is filled with fresh water or a processed liquid to be processed, as in the continuous processing operation. Although the valve 22 is closed, the valve 34 and the valve 36 are open, and the dissolving air flows from the air supply pipe 35.

  The power of the circulation pump 31 becomes heat and is transmitted to the liquid to be processed flowing through the pipe 30 to increase the temperature of the liquid to be processed in the separation unit 13, so that the density of the liquid to be processed is reduced. In order to reduce the density of the liquid to be processed, a heating unit for increasing the temperature of the liquid to be processed may be disposed in the separation unit 13.

  When the liquid to be processed rises to a predetermined temperature, the operation of the circulation pump 31 in the circulation system is stopped, the valve 34 is closed, the valve 22 of the liquid supply system to be processed is opened, and the supply pump 21 is operated. A liquid to be processed in a processing state is supplied. The liquid to be treated flows into the separation unit 13 directly from the pipe 30 and from the pipe 37 and the nozzle 33 through the speed reduction pipe 38.

  Since the liquid to be treated has a lower temperature and a higher density than the fresh water in the separation unit 13 or the processed liquid to be treated, the liquid to be treated accumulates at the bottom of the separation unit 13 and is treated with a low concentration of processed oil having a low temperature and a low density. The liquid is pushed up to the top of the separation unit 13 and discharged from the discharge pipe 41 via the valve 42. For example, the volume from the upper end of the shielding plate 12 to the bottom of the separation unit 13 is 40 L, the temperature of fresh water or treated liquid to be treated is 320 K, the temperature of untreated liquid to be treated is 283 K, and the liquid to be treated is untreated. When the supply is performed at 20 L / h, only the processed liquid to be processed can be discharged by 30 L or more.

  When only the treated liquid to be treated is discharged, the valve 22 and the valve 42 are closed to stop the supply of the untreated liquid to be treated, and the circulation pump 31 performs circulation outside the tank, and the set current is supplied. The electrode 13 is energized. The valve 34 and the valve 36 are opened so that the dissolving air flows from the air supply pipe 35.

  As with continuous processing, the system is operated so that the pressure and flow rate are constant. Also in this case, the power of the circulation pump 31 becomes heat and is transmitted to the liquid to be processed flowing through the pipe 30, the liquid temperature rises, and the amount of dissolved air decreases. For this reason, the relationship between the liquid temperature and the amount of dissolved air is obtained in advance, and the amount of dissolving air to be introduced from the air supply pipe 35 at the liquid temperature obtained by the temperature measuring device 61 rises almost uniformly in the processing tank 11. The operation is adjusted by the valve 34 so that the amount is adjusted. For this reason, large bubbles due to excess air are not continuously generated, and the oil / water separation performance is not deteriorated.

  The valve 42 is closed, and fine bubbles are present in the liquid to be processed in the separation unit 13, and the liquid surface H 1 to be processed is higher than the highest position of the discharge pipe 41. In this state, the scum, which is a metal eluate from the oil and the electrode, is combined with fine bubbles on the upper side of the liquid surface H1 to be treated inside the separation unit 13 and accumulates as floating oil, but the shielding plate is more than the floating oil liquid level H2. 12 is raised (the floating oil liquid level H2 in FIG. 1 is the one during continuous processing operation, and in the intermittent treatment operation, the slightly lower position is the floating oil liquid surface H2). During the circulation, the floating oil does not overflow from the shielding plate 12 to the floating oil receiving portion 14.

  The oil below the separation unit 13 is ejected together with the fine bubbles to the separation unit 13 by circulation outside the tank, and is combined with the metal eluate from the electrode 15 to form a scum. Separate oil and water.

  When the liquid to be treated in the separation unit 13 is reduced to the target oil concentration and a treated liquid is obtained, the circulation pump 31 is stopped, the valve 34 is closed, the valve 22 and the valve 42 are opened, and the electrode 15 is energized. And the supply pump 21 is operated to supply the untreated liquid to be treated from the bottom of the separation unit 13. During this period, the processed liquid to be processed in the upper part of the separation unit 13 flows out from the discharge pipe 41 by the same amount as the newly supplied unprocessed liquid to be processed.

  When the supply pump 21 and the circulation pump 31 are alternately operated and stopped for supplying and circulating the liquid to be treated as described above, and the difference between the floating oil liquid level H2 and the liquid surface H1 is increased, When the floating oil has accumulated on the upper part of the separation unit 13, the valve 42 of the discharge pipe 41 is closed during operation of the supply pump 21, and the liquid surface H 1 to be processed is flush with the shielding plate 12. It overflows from the upper end of the shielding plate 12 and is discharged to the floating oil receiver 14.

  As described above, according to the present invention, even in an oil / water separator using electrolytic levitation using electrolysis, scum, which is a metal eluate associated with the oil content of the liquid to be treated, is precipitated on the bottom of the liquid to be treated. It is possible to float on the upper part of the liquid to be treated and collect the oil and water with high performance without cleaning the inside of the treatment tank.

It is a figure which shows the oil-water separator which becomes one Embodiment of this invention. It is a figure explaining the arrangement | positioning relationship of the deceleration pipe and electrode of the oil-water separator shown in FIG. It is a figure explaining the other arrangement | positioning relationship of the reduction pipe and an electrode in an oil-water separator.

Explanation of symbols

11 ... Processing tank
12 ... Shield plate
13 ... Separation processing tank (separation part)
14 ... Floating oil receiver
15: Positive and negative electrodes
16 ... Partition plate
17 ... Pocket-shaped suction part
21 ... Supply pump
22, 34, 36, 42 ... valve
23, 30, 35, 37, 41, 51 ... piping
31 ... circulation pump
33 ... Nozzle
38 ... Deceleration pipe
61 ... Temperature measuring instrument

Claims (6)

In the oil-water separation method in which electrolysis is performed with at least one pair of positive and negative electrodes for the liquid to be treated contained in the separation treatment tank,
An oil-water separation method characterized in that fine bubbles are gently supplied from the side of each electrode so as to surround each electrode when electrolysis is performed. 2. The oil / water separation method according to claim 1, wherein fine bubbles are supplied from the side so as to move in parallel with the surface of each electrode. 2. The oil / water separation method according to claim 1, wherein the fine bubbles are generated when the liquid to be treated which is pumped out of the separation treatment tank and in which the air is dissolved is ejected from the nozzle. A separation treatment tank in which at least a pair of positive and negative electrodes are arranged for containing the liquid to be processed and electrolyzing the liquid to be processed, and a floating oil receiving portion for collecting the scum generated and floated during the electrolysis In the provided oil-water separator,
An oil-water separator characterized in that a nozzle for injecting a liquid to be treated in which air is dissolved into the side wall of the separation treatment tank to the liquid to be treated in the separation part is provided. 5. The oil / water separator according to claim 4, wherein air to be treated is pumped out of the separation processing tank by air supply means and sprayed from a nozzle provided in the separation processing tank to separate the processing liquid. An oil-water separator having a circulation piping system that returns to a treatment tank and a supply piping system that supplies an untreated liquid to be treated to the separation treatment tank. 5. The oil / water separator according to claim 4, wherein the air supply means has an air supply amount corresponding to the pressure, flow rate and temperature of the liquid to be treated.

Images