JP3092013B2 - Oil-water separator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil / water separation apparatus, and more particularly to a method of passing water to be treated, such as sewage containing oil, oil ball particles and oil-containing sludge, through a water tank arranged in a plurality of stages in series. The present invention relates to an oil-water separation device that floats and separates oil, oil ball particles, oil-containing sludge, and the like by bonding them to air bubbles.

[0002]

2. Description of the Related Art Drainage such as floor washing water and rainwater is drained from oil or oil balls in a work place where oil may flow to the floor on a daily basis, such as a car repair or dismantling factory, a machine shop or a gasoline gas station. This is wastewater containing particles and oil-containing sludge. This wastewater is collected in gutters, sent to an oil-water separator, and discharged to sewage or rivers after oil is removed.

Conventional oil / water separators include a so-called API oil separator conforming to the design standards of the American Petroleum Institute, a PPI oil separator in which a plurality of rows of inclined plates are arranged in a tank,
Alternatively, there is a CPI oil separator using a wavy inclined plate, and in principle, an ordinary horizontal flow type sedimentation basin or a gravity separation type in which an inclined plate is combined therewith is mainly used.

In the conventional API oil separator, in order to keep the average flow velocity of the water to be treated in the tank below the limit value, the length of the tank must be increased as the size of the oil droplet to be removed becomes smaller. Therefore, there is a drawback that a large equipment area is required to almost completely remove suspended oil droplets in the water to be treated, and an additional filter type oil removing device must be provided.

[0005] In addition, the PPI oil separator and the CPI oil separator have a complicated structure inside the tank and are large in scale, require special techniques for handling and maintenance, and have a limit in the ability of the treatment capacity to follow fluctuations in the flow rate of the water to be treated. Therefore, when treating wastewater containing oil in an outdoor factory or the like, it is inevitable that the oil will be mixed into the wastewater in rainy weather.

[0006] Further, as one of the methods of floating separation of suspended substances in water, air bubbles are adhered to suspended substances having a density higher than that of water to reduce the apparent specific gravity and to quickly float. A pressurized flotation method for separation is also known, but in this case, it is necessary to generate fine bubbles, and a large scale is used to pressurize the water to be treated and dissolve the air before releasing it to atmospheric pressure. There is a drawback that a complicated equipment is required.

[0007]

The present invention is suitable as a wastewater treatment device for wastewater containing oil, oil balls, oil-containing sludge, etc., particularly in facilities where there is a risk of rainwater mixing. Accordingly, an object of the present invention is to provide an oil-water separator having a simple structure which can be configured with a relatively small facility area.

[0008]

According to the first aspect of the present invention, there is provided an oil-water separation apparatus for separating and floating oil by passing water to be treated such as sewage mixed with oil through a plurality of water tanks arranged in series. In the oil-water separation device, a receiving tank for receiving the water to be treated from the upper opening, a plurality of stages arranged in series from upstream to downstream to receive and sequentially calm the water to be treated from the lower part in the receiving tank. A sedation tank, an oil collection tank that takes in at least the surface oil water of the sedation tank at the downstream end as an overflow, a bubble generator that generates air bubbles in the water to be treated in the sedation tank, and an overflow that is taken into the oil collection tank. It is provided with a circulation pump means for returning to the receiving tank, and a drain means for discharging the oil-separated water to the outside from the bottom of the calming tank at the downstream end.

In the oil-water separator according to the second aspect of the present invention, the circulating pump includes means for removing solids from the overflow taken into the oil collecting tank, and the solids are removed. It is configured so that the later oil / water is returned to the receiving tank.

[0010] In the oil-water separation device according to the third aspect of the present invention, the bubble generating device includes a perforated nozzle arranged at the bottom of the calming tank, and an air supply device for sending air to the nozzle. .

[0011] In the oil-water separator according to the fourth aspect of the present invention, the sedation tank includes a pair of adjacent sedation tanks communicating with each other at a bottom portion. In addition to the above, another sedation tank which is communicated with the sedation tank on the downstream side of the adjacent sedation tank at the surface layer portion is further included.

In the oil-water separation device according to the invention, the receiving tank is connected to the calming tank at the upstream end by a rising flow path immediately above the sludge pool at the bottom.

In the oil-water separator according to the present invention, the receiving tank receives the reflux of the oil and water by the circulation pump means, and the final collection and removal of the oil is performed from the receiving tank by a vacuum car or the like. For this reason, the receiving tank has a larger capacity than the individual tanks of the calming tank.

In the oil-water separation device according to the present invention, the level of the overflow taken into the oil collecting tank in the oil collecting tank is detected to maintain the overflow of the circulation pump means. Control means for controlling the driving as described above.

[0015] In the oil-water separation device according to the ninth aspect of the present invention, the oil collecting tank is positioned in the calming tank at the downstream end so that an upper edge thereof is slightly sunk below the surface of the water to be treated. It has.

According to a tenth aspect of the present invention, there is provided an oil-water separator, wherein the independent vessel is suspended and supported in the water to be treated according to a floating principle. Are supported by a support so that the height position of the upper edge can be adjusted.

According to a twelfth aspect of the present invention, in the oil-water separation device according to the ninth aspect, the circulating pump means includes a submersible pump disposed in the independent vessel.

[0018]

In the oil-water separator according to the first aspect of the present invention, the water to be treated, such as mixed sewage such as oil, oil balls and oil-containing sludge, is passed through a plurality of water tanks arranged in series. When the oil is floated and separated, the water to be treated from the gutter or the like flows into the receiving tank from the upper opening.

In the receiving tank, turbulence is generated near the surface layer to cause mixing. However, in the bottom tank having a relatively deep water depth, the mixing due to the turbulent flow is slight. Separation is taking place. The water to be treated in the lower part of the receiving tank is guided to the upstream end of the multistage calming tank, and the turbulence of the flow is calmed down toward the downstream to promote the generation of floating oil.

Air bubbles are sent into the water to be treated in these calming tanks by the bubble generator, and the oil balls and oil-containing sludge particles in the water adhere to the air better than water on their surfaces. Because of the oily interface that is likely to occur, these air bubbles adhere to the surfaces of the oil ball particles and the oil-containing sludge particles, whereby these particles quickly float and become the surface residue.

An oil collecting tank is provided at least at the downstream end of these calming tanks. When the surface layer of the water to be treated flows into the oil collecting tank as an overflow, the floating residue floating on the surface layer is rapidly collected at a high flow velocity. It is taken into the oil tank. The overflow taken into the oil collecting tank contains a high proportion of floating residue, and the overflow is returned to the receiving tank from its upper opening by a circulation pump means. On the other hand, water containing almost no oil remains at the bottom of the downstream end of the calming tank, and thus the oil-separated water flows out from the downstream side of the calming tank to an external discharge system and is discharged. You.

In the oil / water separation device of the present invention, since the oil water having a high oil content is recirculated from the calming tank on the downstream side to the receiving tank on the upstream side by the oil collecting tank and the circulating pump means, the circulation of the oil water by the reflux is continued. As a result, the floating oil and floating residue gradually accumulate in the upper layer of the receiving tank. The floating oil and floating residue in the upper layer of the receiving tank can be easily visually confirmed when the receiving tank is observed from the upper opening, but of course, even if the state of the pool is automatically detected by an oil detector installed at an appropriate depth. Good.

When the floating oil and the floating residue accumulate to a certain extent in the upper layer of the receiving tank, the floating oil and the floating residue may be suctioned by a vacuum to be processed by an oil processing company. At this time,
It is convenient if the settled sludge collected at the bottom of the receiving tank is suctioned by vacuum.

In this manner, the separated oil and sludge can be efficiently collected by sucking and removing the floating oil, floating residue and sludge from the receiving tank regularly or irregularly. Since the oil is efficiently removed by the oil-water separation system of the type, almost no oil is recognized in the treated wastewater which is taken out from the bottom of the calming tank at the downstream end and discharged to the outside.

In the oil / water separator of the present invention, the configuration of each tank is extremely simple as compared with the conventional one, and the bubble generator does not need to be of the pressurized type. It can be prefabricated by welding assembly or can be provided as a molded article of fiber reinforced plastic. This eliminates the need for the curing period required for the conventional concrete cast-in-place structure, so that the oil-water separator can be installed overnight, for example, without hindering other business uses at the installation site such as a gasoline filling station. Can be realized.

In the present invention, it is actually desirable to constitute the prefabricated structure or the molded body as described above.
The present invention is also applicable to concrete structures. Further, in the present invention, the bubble generating device is not limited to a device for supplying air bubbles to all of the sedation tank, or air bubbles may be supplied from the bubble generating device to the receiving tank. Further, in the apparatus of the present invention, it is not obstructive to promote the floating of particles by vertically disposing a baffle plate parallel to the flow slightly in an appropriate sedation tank.

In the oil-water separator according to the second aspect of the present invention, the circulating pump includes means for removing solids from the floating residue taken into the oil collecting tank. Only the oil water from which the oil has been removed is returned to the receiving tank, and this oil water contains a high concentration of oil.
As a result, the floating oil mainly accumulates on the surface layer in the receiving tank, and most of the floating residue is separately removed and collected in the circulation pump means, and is again treated by the wetting phenomenon when the floating residue flows into the receiving tank. There is no danger of sinking in water.

In the oil-water separator according to the third aspect of the present invention, the bubble generator includes a perforated nozzle arranged at the bottom of the calming tank and an air supply device for sending air to the nozzle. Thus, the bubble generating device can be easily constituted by a normal air pump (compressor) and a pipe and a porous nozzle or a porous nozzle having a pipe-shaped or flat box-shaped nozzle having a large number of small holes.

In the oil-water separator according to the fourth aspect of the present invention, the sedation tank includes a pair of adjacent sedation tanks that communicate with each other at a bottom portion, whereby the floating oil is settled on the upstream sedation tank. The separated water flows into the downstream calming tank from the bottom and maximizes the gravity separation efficiency of the remaining oil particles to efficiently float, thus efficiently floating and separating oil in each adjacent calming tank Is achieved.
In this case, it is preferable that the bottom communication port between the adjacent sedation tanks has a wide opening in order to make the flow as laminar as possible without disturbance.

[0030] In the oil-water separation device according to the fifth aspect, another sedation tank connected to the downstream sedation tank of the adjacent sedation tank at the surface portion is further provided, and the other sedation tank is provided. The above-mentioned oil collecting tank can be set up. In this way, the floating oil floating on the surface of the upstream calming tank shifts as a laminar flow in the other calming tank, and the oil rises in the upstream calming tank immediately before. The floating oil can be taken into the oil collecting tank without disturbing the separation. Also in this case, it is needless to say that the communication at the surface layer is preferably achieved by a wide or full width passage.

In the oil-water separation device according to the invention, the receiving layer is communicated with the upstream end of the calming tank by a rising flow path immediately above the bottom of the sludge reservoir. The water to be treated near the bottom of the receiving tank is made to flow upward by a pipe or the like and introduced into the upstream end of the calming tank, thereby preventing the sludge at the bottom of the receiving tank from flowing into the calming tank side due to excessive mixing of oil particles. It is simultaneously avoided and reliably prevented.

In the oil-water separation device according to the present invention, the receiving tank receives the return of the oil water by the circulation pump means, and the final collection and removal of the oil is performed by suction from the receiving tank by a vacuum or the like. Therefore, the capacity of the receiving tank is made larger than the individual tanks of the sedation tank to increase the accumulated capacity of the floating oil, and the interval of the suction operation is given a margin.

In the oil / water separator according to the present invention, the circulating pump detects the level of the surface oil in the surface oil water of the sedation tank at the downstream end which overflows into the oil collection tank. Control means for driving and controlling the means so that the overflow is maintained, whereby even if the water depth of the upper edge of the oil collecting tank is constant, the circulation processing of the oil water is performed stably in accordance with the flow rate of the inflowing wastewater. In addition, it is possible to prevent oil from being mixed in the discharged water.

In the present invention, a plurality of circulating systems of floating oil by such an oil collecting tank and a circulating pump means may be provided in a multiplex manner. In this case, it is preferable to collect the floating oil in a plurality of downstream calming tanks. Oil tanks are preferably arranged so that all reflux from each oil collection tank is circulated to the receiving tank. Further, in this case, the control means may include a function of selectively operating some of the circulating systems according to the flow rate of inflow of sewage from outside.

In the oil-water separation device according to the ninth aspect of the present invention, the oil collecting tank is located in the sedation tank at the downstream end so that the upper edge thereof is slightly sunk below the surface of the water to be treated. It has. This is because the oil collecting tank is arranged in the water surface area of the calming tank, the overflow is taken in from the entire periphery of the oil collecting tank, and the flow of the surface tank is made to flow from the entire periphery to the center in the calming tank at the downstream end. The purpose is to make it possible to collect quickly, and to prevent uneven flow toward any edge on the surface layer of the calming tank at the downstream end, and to eliminate poor separation due to uneven distribution of floating oil on the surface layer. .

In the oil-water separator according to the tenth aspect of the present invention, the independent vessel is floated and supported in the water to be treated by the principle of a float, thereby naturally achieving the immersion depth of the independent oil collecting tank by buoyancy balance. In this case, another floating member may be attached to the independent container, or the container itself may be configured to function as a floating member.

[0037] In the oil-water separator according to the eleventh aspect, the height of the upper edge of the independent vessel is supported by a column so as to be adjustable, whereby the immersion depth of the independent oil collecting tank is adjusted to the level of the water to be treated. It can be adjusted accordingly.

According to a twelfth aspect of the present invention, in the oil-water separator according to the ninth aspect, the pump of the circulating pump means is a submersible pump disposed in the independent vessel. This facilitates maintenance and inspection. In this case, if the independent oil collecting container with the pump is configured to be detachable from the sedation tank, the collected oil can be collected from the receiving tank to another container by using this.

The various features of the present invention will be more clearly understood from the following description of the embodiments with reference to the drawings.

[0040]

FIG. 1 is a schematic longitudinal sectional view of an oil / water separator according to a preferred embodiment of the present invention. FIG. 2 is a plan view thereof.

1 and 2, this apparatus constitutes a unit 1 in which a main tank structure is integrated by welding a metal plate, molding fiber-reinforced plastic, or the like. The unit 1 as a whole has a multi-stage tank structure in which a plurality of rigid tanks are arranged in a line toward the side, and connection portions 1a and 1b with the side grooves are formed at the upstream end and the downstream end, respectively. ing.

The entrance-side connecting portion 1a opens to the receiving tank 10, and downstream of the receiving tank 10, first to third sedation tanks 11 to 13 and an inspection tank 14 are arranged in order. The most downstream inspection tank communicates with the discharge side groove 1b at the downstream end.

A plurality of nosles 4 made of porous stone are horizontally disposed at the bottom of the second calming tank 12, and air from an air compressor 6 is supplied to the nozzle 4 from outside of the tank via a pipe (hose) 8. Supplied. As a result, fine air bubbles are generated from the nozzles 4 and adhere to oil ball particles or oil-containing sludge particles in the water to be treated in the tank and cause them to float.

From the receiving tank 10, water to be treated in a relatively lower part thereof is discharged to the surface of the first calming tank 11 through a rising pipe 15, and coarse sludge is provided at a lower end of the rising pipe 15. A simple filter is installed to prevent the particles from flowing down.

The first sedation tank 11 has a wide lower hole 16 formed in a partition wall of the first sedation tank 12 and a second lower sedation tank.
It is in direct communication with the sedation tank 12.

The second calming tank 12 is in direct communication with the third calming tank 13 at the surface layer by a wide recess 17 formed on the upper edge of the partition wall with the third calming tank 13.

With such a communication structure, the water to be treated that has flowed into the receiving tank 10 from the inlet-side connecting portion 1a is transferred to the second calming tank 1
It follows the path meandering up and down to 2.

The flow from the second calming tank 12 to the third calming tank 13 is a simple horizontal shift flow of only the surface layer.

A floating oil collecting tank 20 of a floating type is arranged in the third calming tank 13, and the oil collecting tank 20 has a submersible pump 21 inside. The pump 21 is controlled by the control panel 30 so as to operate only while the level of the water to be treated in the oil collecting tank 20 is detected to be higher than a predetermined level by a level switch (not shown) fixed to the oil collecting tank 20. The to-be-processed water pumped and assembled by the pump 21 is preferably returned to the receiving tank 10 via the sediment removal filter 26 by a pipe 22 including a flexible portion.

In this case, in order to prevent the pump 21 in the oil collecting tank 20 from sucking air, even when the switch does not generate a detection output, the water to be treated enters the oil collecting tank 20 at a level higher than the pump suction port. In this state, the float balance of the oil collecting tank 20 is balanced so that the oil collecting tank 20 is in a state where its upper edge is sunk at a predetermined depth from the water level of the third calming tank 13. It is. Therefore, the surface water to be treated continuously flows into the oil collecting tank 20, but the pump 21 is driven so that the level of the inflowing water to be treated in the oil collecting tank does not catch up with the third calming tank water level.

The third sedation tank 13 and the downstream inspection tank 14 are connected by a riser pipe 18 having one end opening in the lower part of the third sedation tank 13. It is open near the water surface level of the inspection tank 14.

The inspection tank 14 has an oil barrier 19 in the middle of the flow, and the flow passes through the lower end of the oil barrier 19 and flows out from the outlet connection portion 1b to the drain groove. I have. Note that the oil barrier 19 may be a part of the wall structure of the unit 1.

In the oil / water separator of this embodiment, the water to be treated for mixing the oil / water from the gutter flowing into the receiving tank 10 from the inlet connection part 1a flows into the surface oil layer of the receiving tank 10 to wind the oil. The receiving tank 10 is also used for collecting oil from the surface layer of the receiving tank 10 into a separate tank or the like by vacuum. Therefore, as shown by a chain line in FIG.
May be provided.

The water to be treated, which has flowed into the receiving tank 10, flows down while entraining suspended particles such as oil and oil balls and oil-containing sludge particles in the layer, and floats the oil particles by a slight calming effect. While mixed with some suspended particles, the particles flow into the first calming tank 11 from the surface thereof through the two risers 15 in the width direction. In this case, the flow of the coarse particles in the water is prevented from flowing down at the inlet of the riser 15, and therefore, these coarse particles accumulate as sludge at the bottom of the receiving tank 10.

In the first calming tank 11, two rising pipes 15 are provided.
The flow of water near the surface causes less disturbance, so that the treated water effectively floats calmed oil particles.
The water to be treated, which is low in oil particles in the lower layer, then flows into the second calming tank 12 from below through the wide hole 16, where the hole 16 is wide and is not disturbed.

The water to be treated which has flowed into the second calming tank 12 from below is caused to float by exerting a sufficient buoyancy effect on the oil particles, and fine bubbles from the nozzle 4 adhere to the suspended particles during the floating. By reducing the apparent specific gravity, these suspended particles also float quickly, so that the oil particles, oil ball particles and oil-containing sludge particles in the water to be treated are almost floated as floating residues.

The water to be treated in the surface layer of the second calming tank 12 shifts horizontally through the wide recess 17 and flows into the third calming tank 13 together with the residue and the floating oil.
As described above, the oil collecting tank 20 sucks the surface water to be treated as described above, so that most of the surface residue and floating oil flow into the oil collecting tank 20. What escaped the inflow into the oil collection tank 20 was water containing almost no oil particles, which flowed from the lower layer of the third calming tank 13 through the riser pipe 18 to the surface level of the inspection tank 14, It passes under the shield plate 19 and flows out of the outlet connection portion 1b into the drainage groove. The upstream side of the plate 18 of the inspection tank 14 is used for visual inspection of the surface of the final drainage, and if oil is recognized on the surface, the surface water is recirculated.

On the other hand, the water to be treated collected in the oil collecting tank 20 is a floating residue-containing oil / water mixture containing a large amount of oil, since most of the floating residue and floating oil in the surface layer of the third calming tank 13 are recovered. This mixed solution is guided by a pump 21 to a residue removal filter 24 via a pipe 22, and the oil water separated from the residue by the filter 24 is circulated to the receiving tank 10. In this case, the oil water outlet of the filter 24 may be on the upstream side of the partition plate 23 shown by a dashed line in FIG. 1, whereby the surface portion of the receiving tank 10 on the downstream side of the partition plate 23 is used as an oil recovery work area by vacuum or the like. Can be used as a dedicated portion, and an increase in the water content of the recovered oil due to the inflowing oil water at that portion can be prevented. The floating residue separated by the filter 24 is scraped off as a solid containing oil by a scoop or the like.

In the above-described embodiment, the case where the oil collecting tank 20 is a floating type floating tank has been described. However, this is merely an example, and the present invention is not limited to this.

In the modification shown in FIG. 3, a tank chamber 33 is provided on the side wall of the sedation tank via an opening 31, and a gate 32 which can be lifted and lowered from below in the opening 31 is provided in the tank chamber to make the opening level variable. The pump 21 is disposed in the chamber 33 to form an oil collecting tank.

In the modification shown in FIG. 4, the oil collecting tank 40 is not floatable, but is supported by a column 41 installed vertically along the wall of the sedation tank so that the oil collecting tank 40 can be adjusted in height. I have.

Other modifications are also possible. For example, the oil collecting tank may be arranged in a plurality of calming tanks, and the outer shape of the oil collecting tank is not limited to a circular shape but may be various rectangular shapes.

[0063]

As described above, the oil-water separator of the present invention employs a unique circulation system and a bubble mixing system, so that oil, oil ball particles and oil-containing sludge particles can be efficiently separated in a short time. It is possible to effectively cope with the change in the inflow of the water to be treated by controlling the circulation pump, and the bubble generating device can be simply configured with ordinary parts and requires almost no maintenance. Furthermore, since the structure of the tank unit is relatively simple and the installation does not take much time, it is suitable as an oil-water separation device for economical oil-containing sewage in a business facility where rainwater may be mixed, for example, at a gas station. It can be constructed in a short time with a relatively small equipment area due to the unit and unitization.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing an oil-water separator according to a preferred embodiment of the present invention.

FIG. 2 is a schematic plan view of the oil-water separation device according to the embodiment.

FIG. 3 is a partial schematic cross-sectional view showing a modification of the embodiment.

FIG. 4 is a partial schematic sectional view showing another modification of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unit 4 Nozzle 6 Air compressor 8 Piping (hose) 10 Receiving tank 11 1st calming tank 12 2nd calming tank 13 3rd calming tank 14 Inspection tank 20 Oil collecting tank 21 Pump 22 Piping 24 Filter 30 Control panel

Claims (12)

(57) [Claims] An oil-water separation device for separating and separating oil by floating water to be treated such as sewage mixed with oil through a plurality of water tanks arranged in series in a plurality of stages. A plurality of stages of sedation tanks arranged in series from upstream to downstream to receive and treat the water to be treated from the lower part in the receiving tank, and take in the surface oil water of at least the sedation tank at the downstream end as overflow. An oil collection tank, a bubble generator for generating air bubbles in the water to be treated in the sedation tank, a circulating pump means for returning an overflow taken in the oil collection tank to the receiving tank, and a bottom portion of the sedation tank at the downstream end An oil-water separation device, comprising: a drainage unit that discharges oil-separated water from the water to the outside. 2. The circulating pump means includes means for removing solid matter from the overflow taken into the oil collecting tank, and is configured to return the oil water from which the solid matter has been removed to the receiving tank. The oil / water separation device according to claim 1, wherein the oil / water separation device is used. 3. The oil-water separator according to claim 1, wherein the bubble generator includes a perforated nozzle disposed at a bottom of the calming tank, and an air supply device for sending air to the nozzle. 4. The oil-water separator according to claim 1, wherein said sedation tank comprises a pair of adjacent sedation tanks communicating with each other at a bottom. 5. The sedation tank includes a pair of adjacent sedation tanks that communicate with each other at a bottom portion, and further includes another sedation tank that is communicated with a downstream sedation tank of the adjacent sedation tanks at a surface portion. 2. The oil-water separation device according to 1. 6. The oil / water separator according to claim 1, wherein the receiving tank is connected to the sedation tank at the upstream end by a rising flow path immediately above the sludge pool at the bottom. 7. The oil-water separator according to claim 1, wherein the capacity of the receiving tank is larger than that of each of the calming tanks. 8. A control means for detecting a level of the overflow taken into the oil collecting tank in the oil collecting tank and controlling the driving of the circulating pump means so as to maintain the overflow. The oil-water separation device according to claim 1, wherein: 9. The oil-water separation device according to claim 1, wherein the oil collecting tank includes an independent vessel arranged such that an upper edge thereof is slightly set below the surface of the water to be treated in the calming tank at the downstream end. . 10. The oil-water separation device according to claim 9, wherein the independent vessel is suspended and supported in the water to be treated by a float principle. 11. The oil-water separator according to claim 9, wherein the independent container is supported by a column so that a height position of the upper edge can be adjusted. 12. The oil / water separation device according to claim 9, wherein the circulation pump means includes a submersible pump disposed in the independent container.