JP2011020025A - Oil-water separator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil separator capable of reducing the oil concentration of waste liquid and separating and recovering all floating oil even when buoyancy of microbubbles inside treatment target liquid is small, they float in the separator and oil and water are emulsified, in the oil-water separator for surfacing and separating the oil by the oil adsorbing and floating effects of the microbubbles. <P>SOLUTION: In an oil-water separation tank to which the fixed quantity of the oil-mixed waste liquid of an arbitrary flow rate is successively supplied, it is bisected in the direction of flow, a device for generating the microbubbles and a jetting nozzle are provided on the bottom part of the preceding stage, and a partition plate for making the microbubbles float without surfacing to a liquid surface even though they adsorb oil droplets by forced flow by a fixed quantity water supply means and overflow to a post stage is provided. For the post stage, a floating oil recovery chamber is provided to the upstream, a waste liquid discharge chamber is provided to the downstream communicating with the floating oil recovery chamber at the bottom part, and a waste liquid discharge port is provided to a position lower than the oil recovery port of the floating oil recovery chamber. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a measure for purifying oil that meets the wastewater standard value of the Water Pollution Control Law when discharged from a water collection tank or the like in the wash water of the object to which the oil adheres at a factory, substation or gas station. Wastewater treatment of oil-mixed waste liquid with a relatively high oil concentration generated when cleaning oil that adheres to equipment or workpieces, etc. The present invention relates to an oil-water separator used as a measure for separating and collecting oil as a pretreatment for sending water to a tank and reducing the load on a wastewater treatment tank.

  For example, in an electrostatic precipitator that removes mist-like oil floating in machine factories, foundries, etc., oil-water separation that separates oil in oil mixed cleaning wastewater generated when the inside of the device to which oil adheres is cleaned with cleaning liquid It relates to the device.

  Currently, many oil-water separators that float and separate oil components using the difference in specific gravity of oil and water are used for the treatment of oil-mixed waste liquids. In this type of apparatus, a technique for promoting the floating of oil using the oil adsorption and floating effect of fine bubbles has been devised. In other words, micro bubbles such as micro-sized or nano-sized bubbles have the property of adsorbing oil or sludge to the surface of the bubbles with a high surface adsorbing power, so when generating the fine bubbles in the treatment liquid in the tank, A separation target such as fat or sludge can be adsorbed on the bubble surface by the surface adsorption action of the fine bubbles, and the adsorption separation target can be floated and separated in the processing liquid in the tank by the buoyancy of the fine bubbles.

  These techniques are shown in Patent Documents 1 and 2 below.

  The oil / water separation apparatus described in Patent Document 1 discharges fine bubbles so that they rise in order from the lower part of the oil / water separation tank, and increases the lowering speed of the fine bubbles at a rate at which the liquid to be treated flows through the discharge pipe provided at the upper part of the oil / water separation tank It is an apparatus that aims to prevent oil from being mixed into the liquid to be treated so as to be slower than the speed.

  However, this apparatus complicates the apparatus because it is necessary to constantly adjust the air supply bubble by monitoring the liquid temperature of the liquid to be processed and the amount of pressurization of the circulation pump so that the fine bubbles rise in order. Further, depending on the oil concentration of the liquid to be treated that flows, there is a problem that the oil that has been emulsified is mixed into the liquid to be discharged and the separation efficiency is deteriorated, and there is a need for measures or control means such as switching the operation method, It cannot be said that the device is sufficiently simplified.

  The separation device described in Patent Document 2 is a device that floats oil with fine bubbles, and feeds and discharges the treatment liquid remaining in the separation tank to an isolation chamber communicated from the lower part of the separation tank.

  However, in this device, depending on the inflow amount of oil-mixed water, its oil concentration, the amount of fine bubbles generated, and its particle size, the oil-mixed water emulsified by fine bubbles that continue to float in the separation tank is separated from the drain separation chamber. There is a risk that treated water with a very high oil concentration will be discharged.

Japanese Patent No. 4126203 JP 2007-38195 A

  Therefore, the present invention is an oil-water separator that floats and separates oil by the oil adsorption and levitation effect of fine bubbles, and even when the oil and water of the liquid to be treated are emulsified, the buoyancy of the fine bubbles does not float small. An object of the present invention is to provide an oil separation device that can reduce the oil concentration of waste liquid wastewater and can separate and recover without leaving floating oil with a simple configuration without requiring complicated control means.

  In order to solve the above-described problems, an oil / water separation apparatus according to the present invention includes an oil / water separation tank that separates oil and water, and a quantitative water supply unit that sequentially supplies waste liquid at an arbitrary flow rate to the oil / water separation tank. In the direction of the flow, and is divided into a front stage and a rear stage so that the supernatant liquid of the front stage overflows into the rear stage, and the front stage of the oil-water separation tank has a device for generating fine bubbles at the bottom and the fine bubbles An oil / water separation chamber that separates oil and waste liquid up and down by oil adsorption and levitation effect with fine air bubbles equipped with a jet nozzle, and the latter stage of the oil / water separation tank is further divided into two in the flow direction, and the upstream side floated A floating oil recovery chamber for recovering oil; a downstream side is a waste liquid drainage chamber into which the remaining waste liquid is separated and the remaining waste liquid flows; an inlet of the waste liquid drainage chamber is disposed at a lower portion of the floating oil recovery chamber; An oil recovery port leading to the outside of the device is provided at a position lower than the upper end of the partition plate in the recovery chamber, and a waste liquid drain port communicating to the outside of the device is provided at a position lower than the oil recovery port in the waste liquid draining chamber. It is characterized by this.

  According to the present invention, the fine bubbles that adsorb oil droplets in the oil / water separation chamber but do not float up to the liquid level and float are floated up to the upper part of the partition plate by the forced flow by the quantitative water supply means. The fine bubbles that have moved to the upper part of the partition plate have a greater buoyancy when they come into contact with the floating oil, and the fine bubbles that settle or float again in the oil mixed waste liquid are reduced. In addition, fine bubbles that have obtained a large buoyancy at the upper part of the partition plate come into contact with the atmosphere by a slight levitation movement, and burst due to pressure fluctuations. That is, the fine bubbles overflowing the partition plate disappear or have sufficient buoyancy at the later stage and do not settle downward again. Further, in the latter stage, oil separation and waste liquid drainage can be performed simultaneously and simultaneously using the difference in specific gravity, so that the apparatus can be simplified and the separation efficiency can be improved.

  According to the oil / water separation device of the present invention, the oil / water separation tank for separating oil and water, and the quantitative water feeding means for sequentially feeding the waste liquid of an arbitrary flow rate to the oil / water separation tank, the flow in the oil / water separation tank is provided. A partition plate that is divided into a front stage and a rear stage so that the supernatant of the front stage overflows into the rear stage is provided, and the front stage of the oil-water separation tank is provided with a device that generates fine bubbles at the bottom and a nozzle for ejecting the fine bubbles. The oil / water separation chamber separates oil and waste liquid up and down due to the oil adsorption and levitation effect due to the fine bubbles, and the latter stage of the oil / water separation tank is further divided into two in the flow direction, and the upstream side is a floating surface that collects the floating oil It is an oil recovery chamber, the downstream side is a waste liquid drain chamber into which the remaining waste liquid is separated and the remaining waste liquid flows in, the inlet of the waste liquid drain chamber is arranged at the lower part of the floating oil recovery chamber, and further in the floating oil recovery chamber The By providing an oil recovery port leading to the outside at a position lower than the upper end of the partition plate, the waste liquid drainage chamber has a structure in which a waste liquid draining port leading to the outside of the apparatus is provided at a position lower than the oil recovery port, The intended purpose can be achieved. That is, although the oil droplets are adsorbed in the oil / water separation chamber, the fine bubbles that do not float up to the liquid level and float are floated up to the upper part of the partition plate by a forced flow by the quantitative water supply means. The fine bubbles that have moved to the upper part of the partition plate have a greater buoyancy when they come into contact with the floating oil, and the fine bubbles that settle or float again in the oil mixed waste liquid are reduced. In addition, fine bubbles that have obtained a large buoyancy at the upper part of the partition plate come into contact with the atmosphere by a slight levitation movement, and burst due to pressure fluctuations. That is, the fine bubbles overflowing the partition plate disappear or have sufficient buoyancy at the later stage and do not settle downward again. Further, since oil separation and recovery and waste liquid drainage can be performed at the same time using the difference in specific gravity at the latter stage, it is possible to provide an oil / water separation apparatus capable of simplifying the apparatus and improving the separation efficiency.

Schematic which shows the structure of the oil-water separator by Embodiment 1 of this invention. Schematic showing an inclined plate provided in the oil-water separation chamber Schematic showing small balls mixed in the oil-water separation chamber Schematic showing the partition plate part between the oil-water separation chamber and the floating oil recovery chamber

  The invention according to claim 1 is an oil separation device that separates and recovers oil from oil-mixed waste liquid containing oil by utilizing a difference in specific gravity, an oil-water separation tank that separates oil and water, and waste liquid having an arbitrary flow rate. It comprises a quantitative water supply means for sequentially supplying water to the oil / water separation tank, and includes a partition plate that divides the inside of the oil / water separation tank into a front stage and a rear stage in a flow direction so that the supernatant liquid of the front stage overflows into the rear stage, The front stage of the oil-water separation tank is an oil-water separation chamber that separates oil and waste liquid up and down by the oil adsorption and floating effect by the fine bubbles equipped with a device that generates fine bubbles at the bottom and the fine-bubble jet nozzle, The latter part of the tank is further divided into two in the direction of flow, the upstream side is a floating oil recovery chamber for recovering the floating oil, and the downstream side is a waste liquid drain chamber for separating the floating oil and the remaining waste liquid flows in, and the waste liquid Drainage chamber The inlet is arranged at the lower part of the floating oil recovery chamber, and an oil recovery port is provided in the floating oil recovery chamber at a position lower than the upper end of the partition plate. The waste liquid drain port leading to the oil recovery port is provided at a position lower than the oil recovery port. It is levitated to the upper part of the partition plate by forced flow. The fine bubbles that have moved to the upper part of the partition plate have a greater buoyancy when they come into contact with the floating oil, and the fine bubbles that settle or float again in the oil mixed waste liquid are reduced. In addition, fine bubbles that have obtained a large buoyancy at the upper part of the partition plate come into contact with the atmosphere by a slight levitation movement, and burst due to pressure fluctuations. In other words, the fine bubbles overflowing the partition plate disappear in the later stage or have sufficient buoyancy and do not settle down again, so that the separation performance can be improved and the oil can be drained at a low oil concentration, reducing the load on the wastewater treatment tank. It has an effect that can be achieved. In the latter stage, oil separation and recovery and wastewater drainage can be performed simultaneously and simultaneously by utilizing the difference in specific gravity, so that the apparatus can be made compact and maintenance can be saved. In addition, since the waste liquid is not mixed in the recovered oil and the amount of waste can be reduced, the waste disposal cost can be reduced.

  Further, according to the second aspect of the present invention, since the inclined plate is disposed in the oil / water separation chamber, fine bubbles that adsorb oil droplets but do not float with a small buoyancy come into contact with the inclined plate with a slight rising movement and adsorb. Is done. Furthermore, it can obtain greater buoyancy by overlapping with other fine bubbles on the surface of the plate, and can float along the inclination of the plate, so that separation performance can be improved and drainage can be drained at a low oil concentration, so a wastewater treatment tank It has the effect | action which can aim at the load reduction to.

  Further, the invention according to claim 3 is a mixture of small spheres of material having a specific gravity smaller than water and having hydrophobicity in the oil / water separation chamber, so that fine bubbles that adsorb oil droplets but have low buoyancy and do not float, Separation performance because it is possible to get more buoyancy by associating with small spheres before they ascend to the upper water surface of the partition plate by forced flow by the quantitative water supply means, and by surfacing with other fine bubbles on the sphere surface to obtain greater buoyancy. Since the water can be drained at a low oil concentration, the load on the waste water treatment tank can be reduced.

  Further, in the invention according to claim 4, since the upper surface of the partition plate is made uneven, the oil mixed waste liquid containing fine bubbles moving on the upper portion of the partition plate becomes turbulent and has a probability of coming into contact with the floating oil and the atmosphere. The fine bubbles that overflow and overflow the partition plate disappear more or have sufficient buoyancy in the latter part of the oil / water separation tank and do not settle again below the mixed waste liquid, so that the separation performance can be improved and drained at a low oil concentration Therefore, it has the effect | action which can aim at the load reduction to a wastewater treatment tank.

  Further, the invention according to claim 5 is provided with means for blowing air vertically downward toward the upper surface of the partition plate, so that the oil mixed waste liquid containing fine bubbles moving on the upper portion of the partition plate is stirred in the vertical direction. The probability of contact with floating oil and the atmosphere increases, and the fine bubbles overflowing the partition plate disappear more or have sufficient buoyancy at the latter stage of the oil-water separation tank, and do not settle again below the mixed waste liquid, thus improving the separation performance It can be drained with a low oil concentration, and has the effect of reducing the load on the wastewater treatment tank.

  In the invention of claim 6, the horizontal cross-sectional area of the floating oil recovery chamber is made smaller than the horizontal cross-sectional area of the waste liquid drainage chamber, so that the thickness of the floating oil layer flowing into the floating oil separation chamber is increased. Since the water level difference increases, the separation performance can be improved, and drainage can be performed at a low oil concentration, so that the load on the wastewater treatment tank can be reduced.

  Further, the invention according to claim 7 is the oil that floats above the floating oil recovery chamber by providing air blowing means so as to form a flow path for conveying the floating oil to the oil recovery port in the floating oil recovery chamber. Is reliably and quickly carried to the floating oil recovery port, so that the separation efficiency can be increased and drainage can be performed at a low oil concentration, so that the load on the wastewater treatment tank can be reduced. Further, since the liquid level always flows, the floating oil can be prevented from solidifying, and the operation can be saved.

  In the invention according to claim 8, air blowing means is provided in the floating oil recovery chamber toward the wall surface of the floating oil recovery chamber, and a vortex is generated in the upper layer of the floating oil recovery chamber, whereby a negative pressure is applied to the vortex center. At the surface of the mixed oil waste liquid in the floating oil recovery chamber, a flow that causes the floating oil to be drawn into the center of the vortex occurs, and the dispersed floating oil can be collected at the center of the vortex. Since the oil can be discharged from the floating oil recovery port to the outside of the machine, the amount of oil to be recovered can be increased, the separation performance can be improved, and drainage can be performed at a low oil concentration, so that the load on the wastewater treatment tank can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a configuration diagram of an oil-water separator in Embodiment 1 of the present invention.

  Oil mixed waste liquid generated at a factory, substation, gasoline station, etc. is temporarily stored in an oil mixed waste liquid storage tank (not shown), and is sent to the oil / water separation tank 1 via a quantitative water supply device (not shown). . The oil / water separation tank 1 is a container formed of, for example, stainless steel or polypropylene resin. The oil / water separation tank 1 is divided into three stages in the direction of the waste liquid flow, and comprises an oil / water separation chamber 2, a floating oil recovery chamber 3, and a waste liquid drain chamber 4 from the previous stage. The oil-mixed waste liquid (oil-water emulsion 11) fed from the fixed-quantity water feeding device flows from an oil-water separation chamber inlet 21 provided below the oil-water separation chamber 2. Here, the capacity | capacitance of the oil-water separation chamber 2 is made into about 1/8 of the capacity | capacitance of the oil content mixing waste liquid storage tank into which the whole quantity of process target liquid is poured. Furthermore, the flow rate of the quantitative water supply device can be set to a flow rate for supplying the entire amount of the liquid to be treated poured into the oil mixed waste liquid storage tank over 2 to 24 hours. The piping of this apparatus has a diameter of 10 mm or more in consideration of the viscosity and clogging of the oil mixed waste liquid. A fine bubble generator 5 is provided at the bottom of the oil / water separation chamber 2. The fine bubble generating device 5 may be a method in which, for example, compressed air passes through a porous ceramic or sintered alloy to generate bubbles, or air is mixed with oil using a negative pressure generated by a water flow. A method of generating fine bubbles by entraining in the waste liquid and shearing the air by relative movement with the water flow may be used. Note that the nozzles of the fine bubble generating device 5 are provided so that the fine bubbles 9 are distributed throughout the oil-water separation chamber 2.

  In addition, a partition plate 6 is provided between the oil / water separation chamber 2 and the floating oil recovery chamber 3 as a sill from which oil floating in the oil / water separation chamber 2 overflows into the floating oil recovery chamber 3. The partition plate 6 is arranged so that the supernatant liquid collected in the oil / water separation chamber 2 overflows into the floating oil recovery chamber 3. Further, the partition plate 6 is shaped so that the flow rate of the oil-mixed liquid overflowing the upper portion of the partition plate 6 is minimized by increasing the upper surface area.

  Next, a waste liquid drain chamber inlet 12 is provided at the bottom of the floating oil recovery chamber 3 so as to communicate with the waste liquid drain chamber 4. The waste liquid remaining after separating the floating oil 10 flows into the waste liquid drainage chamber 4. Here, a floating oil recovery port 7 that leads to the outside of the apparatus is provided at a position lower than the partition plate 6 inside the floating oil recovery chamber 3, and a waste liquid drain port 8 that similarly leads to the outside of the apparatus inside the waste liquid drain chamber 4. Is provided at a position lower than the partition plate 6 and the floating oil recovery port 7.

  Subsequently, the floating oil 10 and the waste liquid separated by the oil / water separation chamber 2 and the partition plate 6 individually raise the water levels in the floating oil recovery chamber 3 and the waste liquid drainage chamber 4 according to the respective inflow amounts, and the floating oil recovery port 7 or when the height of the waste liquid drain port 8 is exceeded, the oil falls or drains the waste liquid.

  Here, one floating oil recovery chamber 3 and one waste liquid drain chamber 4 are provided in the subsequent stage of the oil / water separation chamber 2, but a plurality of similar waste liquid drain chambers are continuously provided in the subsequent stage of the waste liquid drain chamber 4, If the waste liquid is drained from the waste liquid drain chamber 4 at the rearmost stage, the separation performance is enhanced.

  Here, the horizontal cross-sectional area of the floating oil recovery chamber 3 and the waste liquid drain chamber 4 is the same, but if the horizontal cross-sectional area of the floating oil recovery chamber 3 is smaller than that of the waste liquid drain chamber 4, the inside of the floating oil recovery chamber 3 The thickness of the floating oil 10 increases, and the difference in water level from the waste liquid increases and the separation performance increases.

  Further, here, the floating oil recovery port 7 is provided in the center of the horizontal section of the floating oil recovery chamber 3 and opens upward, and is arranged so as to overflow downward when the liquid level of the floating oil 10 exceeds the opening height. Thus, only the supernatant of the floating oil 10 can be discharged, and the concentration of the oil to be recovered increases.

  In FIG. 2, the inclined plate 13 provided in the oil-water separation chamber 2 is shown. The inclined plate 13 is a thin plate made of, for example, polypropylene resin, and a plurality of plates are arranged at equal intervals and arranged at a constant angle so that the downstream direction becomes higher. Here, the angle of the inclined plate 13 is about 30 to 80 degrees. Although the oil droplets are adsorbed in the oil / water separation chamber 2, the fine bubbles 9 that do not float up to the liquid level and float are brought into contact with the inclined plate 13 and adsorbed by a slight floating movement. Furthermore, it is possible to obtain a greater buoyancy by overlapping with the other fine bubbles 9 on the surface of the inclined plate 13 and to rise to the liquid surface along the inclination of the plate, so that the separation efficiency is increased.

  FIG. 3 shows a small ball 14 mixed in the oil / water separation chamber 2. The small sphere 14 is a material having a specific gravity smaller than that of water and having hydrophobicity, and is formed of, for example, a polypropylene resin. The small sphere 14 is a sphere having a diameter of about 10 to 50 mm, but is not necessarily a sphere. In the oil / water separation chamber 2, fine bubbles that adsorb oil droplets but have low buoyancy and do not rise are brought into contact with and adsorbed on the small sphere 14 before rising to the upper surface of the partition plate by forced flow by the quantitative water supply means. By overlapping with the fine bubbles 9, a greater buoyancy can be obtained and the buoyancy can be achieved, thereby increasing the separation efficiency.

  FIG. 4 shows the partition plate upper surface 15 having an uneven shape. Due to the concavo-convex shape, the flow of the oil-mixed waste liquid containing the fine bubbles 9 moving above the partition plate 6 becomes turbulent, and the probability that the fine bubbles 9 come into contact with the floating oil 10 and the atmosphere increases. The fine bubbles 9 overflowing the partition plate 6 disappear in the floating oil collection chamber 3 or have sufficient buoyancy and rise again without sinking downward, so that the oil adsorbed on the fine bubbles 9 is collected. And separation performance is enhanced.

  In addition, a means (air blowing means 16) for blowing air vertically downward toward the partition plate upper surface 15 is provided. Here, the air blowing flow rate and the flow velocity are adjusted to such an extent that the oil mixed waste liquid does not flow backward on the partition plate upper surface 15. By blowing air, the oil-mixed waste liquid containing the fine bubbles 9 that move on the upper surface 15 of the partition plate is agitated in the vertical direction, and the probability of coming into contact with the floating oil 10 and the atmosphere increases. The fine bubbles 9 overflowing the partition plate 6 disappear in the floating oil collection chamber 3 or have sufficient buoyancy and rise again without sinking downward, so that the oil adsorbed on the fine bubbles 9 is collected. And separation performance is enhanced.

  Further, air blowing means 16 is provided in the floating oil recovery chamber 3 so as to form a flow path for carrying the floating oil 10 to the floating oil recovery port 7. By blowing air, the oil that has floated to the upper layer of the floating oil recovery chamber 3 can be reliably and promptly conveyed to the floating oil recovery port 7 and the separation performance is enhanced. In addition, since the liquid level always flows, the floating oil can be prevented from solidifying.

  The floating oil recovery chamber 3 is provided with air blowing means 16 toward the wall surface of the floating oil recovery chamber 3. By blowing air, a vortex is generated in the upper layer of the floating oil recovery chamber 3, a negative pressure is generated at the center of the vortex, and a flow in which the floating oil 10 is drawn into the center of the vortex is generated and dispersed. The floating oil 10 can be collected at the center of the vortex, and the oil collected at the center can be discharged from the floating oil collection port 7 to the outside of the machine, so that the amount of oil to be collected is increased and the separation performance is improved.

  The oil / water separator according to the present invention is a measure for purifying to an oil that meets the wastewater standard value of the Water Pollution Control Law when discharged from a water collection tank or the like in the treatment of oil-mixed water generated at factories, substations, gas stations, etc. Oil / water separation equipment used as a coolant, or processing of coolant such as metal cutting and polishing in factories, etc., or oil mixed washing wastewater with a relatively high oil concentration generated when cleaning oil adhering to equipment or workpieces It can be used in an oil / water separator used as a measure for separating and recovering oil as a pretreatment for sending water to a wastewater treatment tank and reducing the load on the wastewater treatment tank.

DESCRIPTION OF SYMBOLS 1 Oil-water separation tank 2 Oil-water separation chamber 3 Floating oil collection chamber 4 Waste liquid drainage chamber 5 Fine bubble generator 6 Partition plate 7 Floating oil collection port 8 Waste liquid drain port 9 Fine bubble 10 Floating oil 11 Oil-water emulsion 12 Waste liquid drain chamber entrance 13 Inclined plate 14 Small ball 15 Partition plate upper surface 16 Air spraying means 21 Oil water separation chamber inlet

Claims (8)

An oil separation device that separates and recovers oil from oil-mixed waste liquid containing oil by utilizing a specific gravity difference, and sequentially feeds an oil-water separation tank that separates oil and water, and an arbitrary flow rate of waste liquid to the oil-water separation tank. The oil / water separation tank is divided into a front stage and a rear stage in the direction of flow, and a partition plate is provided so that the supernatant liquid of the front stage overflows into the rear stage, and the front stage of the oil / water separation tank has a bottom portion. And an oil / water separation chamber for separating oil and waste liquid up and down by the effect of oil adsorption and levitation by the fine bubbles equipped with a device for generating fine bubbles, and the latter stage of the oil / water separation tank The upstream side is a floating oil recovery chamber that collects floating oil, the downstream side is a waste liquid drainage chamber that separates the floating oil and the remaining waste liquid flows in, and the inlet of the waste liquid drainage chamber is the floating oil recovery chamber Recovery In addition, an oil recovery port that communicates outside the apparatus is provided at a position lower than the upper end of the partition plate in the floating oil collection chamber, and a waste liquid drain port that communicates outside the apparatus is provided in the waste liquid drain chamber. An oil / water separator characterized by being provided at a position lower than the oil recovery port. The oil / water separator according to claim 1, wherein an inclined plate is disposed in the oil / water separator chamber. 3. The oil / water separator according to claim 1, wherein hydrophobic spheres having a specific gravity smaller than water are mixed in the oil / water separation chamber. The oil-water separator according to any one of claims 1 to 3, wherein the upper surface of the partition plate has an uneven shape. The oil-water separator according to any one of claims 1 to 4, further comprising means for blowing air vertically downward toward the upper surface of the partition plate. The oil / water separator according to any one of claims 1 to 5, wherein a horizontal cross-sectional area of the floating oil recovery chamber is smaller than a horizontal cross-sectional area of the waste liquid drainage chamber. The said floating oil collection | recovery chamber was equipped with the air spraying means which sprays air so that the flow path which conveys floating oil to the said oil collection port may be formed. Oil-water separator. The oil / water separator according to any one of claims 1 to 7, wherein the air blowing means is provided toward a wall surface of the floating oil recovery chamber to generate a vortex in the upper layer of the floating oil recovery chamber.

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