JP2954058B2 - Wastewater treatment apparatus and wastewater treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for treating wastewater containing oil, and more particularly, to the treatment of oil-containing water containing fine emulsified oil.

[0002]

2. Description of the Related Art Conventionally, coagulation sedimentation, distillation, centrifugation, pressurized flotation, filtration, coagulation pressure sedimentation, etc. have been proposed for treating oil in oil-containing water. The most widely used method is the coalescence method (Reference: Industrial Cleaning Technology Handbook, August 31, 1994, published by Realize Inc., Chapter 14 Related Technologies, pp. 296-300) ).

[0003] The coalescence method will be described with reference to the drawings. FIG. 3 is a configuration example of a wastewater treatment device for oil-containing water using a coalescence method. The oil-containing water 2 in the storage tank 1 is supplied to the oil treatment tank 4 by the pump 3. A coalescer filter 5 is mounted in the oil processing tank 4,
Oil treatment is performed by passing oil-containing water horizontally from inside to outside of the filter 5. The treated processing liquid 6 is returned to the storage tank 1 again from the outlet at the bottom of the oil processing tank.

Next, the principle of oil removal by the coalescer filter 5 will be described with reference to FIG. Most of the oil in the oil-containing water is finely dispersed oil 7 (having a particle diameter of about 10 μm or more) and is mixed with the oil due to physical force such as stirring by a liquid flow. When the dispersed oil 7 is supplied to the coalescer filter 5 in the direction A, the dispersed oil 7 is captured by the ultrafine fibers forming the coalescer filter 5, and the oil particles are then aggregated and coarsened to form oil particles. Growing large, finally oil particle diameter 1m
When it grows to about m, it is pushed out of the coalescer filter 5 by water pressure. Since the extruded coarse oil droplets 8 have a specific gravity difference from water (water specific gravity> oil specific gravity), they float up to the water surface in a short time and are separated from the water.

[0005]

However, in the conventional wastewater treatment method for oil-containing water, the particle size of the emulsified oil is too fine, so that the mechanical fiber structure alone cannot sufficiently exert the oil coagulation function. Therefore, emulsified oil (diameter 1) having a smaller particle diameter than oil dispersed in oil-containing water (particle diameter of about 10 μm or more)
(μm or less), the emulsified oil cannot be removed, and as a result, the oil contained in the oil-containing water and the removal efficiency deteriorate.

In addition, because of the filter structure that allows the processing liquid to flow in the horizontal direction, it is difficult for coarse oil droplets to float easily, and the coarse oil droplets processed near the outlet of the oil processing tank are affected by the flow of the processing liquid flowing out. You get caught and you can't fly.

[0007] Therefore, coarse oil droplets that cannot be lifted upward and are caught in the flow of the processing liquid are returned to the original storage tank again, and as a result, the oil-water separation efficiency is reduced.

[0008]

According to the present invention, there is provided a method for treating wastewater, comprising the steps of: pumping oil-containing water from a storage soda to an oil treatment tank (lower or bottom portion) via a pump; Oil / water separation comprising a resin fiber filled with a filter part provided inside the oil treatment tank and having fine particles of an inorganic compound having a three-dimensional network structure and a large number of protrusions on the surface and having a positive charge in water. The material is characterized by forcibly aggregating the oil droplets of the oil-containing water that have been fed by the material to make the oil droplets coarse, and separating the oil component by a difference in specific gravity with water.

The pumped oil-containing water is supplied from a lower portion of the filter portion, passes through the oil-water separator vertically stacked inside the filter from below to above, and is discharged from an upper portion of the filter. It is characterized by being performed.

The wastewater treatment apparatus of the present invention is a wastewater treatment apparatus for oil-containing water; a storage tank for storing oil-containing water; and at least one cylindrical or polygonal cylindrical upper surface having a predetermined height. It is covered with a detachable lid having a hole of a predetermined size as described above, is provided with a first inlet for supplying the oil-containing water at the center of the bottom surface, and has a three-dimensional network structure inside and a projection on the surface. A filter portion in which the oil-water separation material made of resin fibers having fine particles of an inorganic compound that is positively charged in water and is arranged in a cylindrical shape is filled in the inside of the cylindrical shape; and a cylindrical or polygonal shape having a predetermined height. A second inlet for supplying the oil-containing water to a central portion of the bottom portion, the second portion having an open top portion, and an oil discharge port for discharging oil separated from the upper portion of the cylindrical portion,
A processing liquid circulation port for circulating the processing liquid from which oil is separated to the storage tank at the lower part of the cylindrical or polygonal cylindrical shape, and the first inlet at the center of the bottom of the filter unit is provided. An oil treatment tank engaged with (joined, seated, locked, attached to) a second inlet; and filtering the oil-containing water stored in the storage tank through first and second inlets. And a pump for pumping the pressure inside the unit.

Further, the oil-water separation material is characterized in that the resin fibers having a predetermined thickness are vertically stacked and filled in the filter portion.

As described above, the present invention relates to a resin fiber filled in a filter and having a three-dimensional network structure, and a plurality of inorganic compounds arranged in a projecting manner on the surface of the resin fiber and having a positive charge in oil-containing water. Using an oil-water separation material provided with fine particles, an emulsified oil having a negative charge due to interfacial friction with water can be captured by fine particles of an inorganic compound, and oil-containing water treatment including the emulsified oil is performed.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a diagram showing a main configuration of a wastewater treatment device of the present invention. FIG. 2 is a diagram for explaining the principle of oil treatment by the oil-water separator.

The wastewater treatment apparatus shown in FIG. 1 includes a storage tank 1 for storing oil-containing water, an oil treatment tank 4, a pump 3 for pumping oil-containing water from the storage tank to the oil treatment tank, and a pressure gauge 21.
And a treatment oil liquid circulation valve 20. The oil treatment tank has a filter 15 for separating oil from oil-containing water pumped therein by a pump, an oil-containing water inlet 16 for supplying oil-containing water, and A treatment liquid circulation port 17 for circulating the dispersion liquid from which the oil has been separated to the storage tank, and an oil discharge port 18 for discharging the separated oil to the outside.

The oil-containing water 2 in the storage tank 1 is supplied by a pump 3 to an oil-treating water inlet 16 of an oil treatment tank 4. In the oil treatment tank 4, resin fibers forming a three-dimensional network structure,
A filter 15 on which an oil-water separation material 9 having a large number of protrusions arranged on the surface of the resin fiber and fine particles of an inorganic compound having a positive charge in oil-containing water is mounted in a stacked manner;
The oil-containing water 2 passes through the inside of the oil-water separation material 5 from below, so that the emulsified oil having a negative charge due to interfacial friction with water is captured by the fine particles of the inorganic compound, The emulsified oil is processed. The processing liquid 6 subjected to the oil processing is supplied from the processing liquid circulation port 17 at the bottom of the oil processing tank 4 to the storage tank 1.
Is returned to.

The oil-water separator 9 shown in FIG. 2 is made of a nonwoven resin fiber 10 having a three-dimensional network structure, and a large number of fine particles of an inorganic compound 11 are arranged on the surface thereof in a projecting manner. The resin fiber 10 can be manufactured by a known burst fiber method or the like, and requires a pre-process of mixing the particulate material with the resin fiber material.

As the resin fiber 10, a material having lipophilicity and high hydrophobicity is used. Among them, polyolefin resin fiber is excellent in terms of production and cost. In order to increase the contact area with the fine emulsified oil 12, the fiber diameter is 30 μm.
m or less is more preferable, as long as the fiber itself is a hollow fiber having a porous structure.

Examples of the inorganic compound 11 forming fine particles include: a substance which is positively charged in water by dissociation of its surface or by Nernst type charging;
For example, barium sulfate BaSO ₄ (Reference: Oct. 20, 1994, published by Maki Shoten, 28th edition of Chemical Engineering,
Pages 33 to 35) and aluminum oxide Al ₂
O ₃ , magnesium oxide MgO, magnesium hydroxide M
g (OH) _{2 and the} like are good.

It is important to balance the particle diameter of the fine particles with the fiber diameter of the resin fiber 10. For example, if an inorganic compound having a particle diameter exceeding 20 μm is contained in a 20 μm fiber, the mechanical strength of the fiber is reduced. It is necessary to keep the particle diameter smaller than the fiber diameter.

When the oil-water separation material 9 is used and the emulsified oil 12 having a diameter of about 1 μm is supplied in the direction of arrow A as shown in FIG. 2B, the emulsified oil 12 forms a three-dimensional network structure. Pass through the gap between the resin fibers 10 to be formed. At this time, the emulsified oil 12 advances while contacting or colliding with the intermingled resin fibers 10, and thus also contacts the fine particles of the inorganic compound 11.

The surface of the fine particles of the inorganic compound 11 is positively charged by Nernst-type charging or dissociation of the surface. As shown in FIG. 2B, one emulsified oil 12 has water surrounding it. Since zeta potential is generated due to interfacial friction with the inorganic compound 11 and is negatively charged, it is electrically attracted to the fine particles of the inorganic compound 11 and captured.

The fine particles of the inorganic compound 11 are resin fibers 1
Since it protrudes into the gap of 0, the fiber interval is narrowed, and the opportunity for contact between the emulsified oil 12 and the resin fiber is also improved. The oil / water separator 9 is vertically stacked in the filter 15, and the oil / water separation is performed by the amount of the filled oil / water separator 9 according to the present principle.

The surface of the fine particles of the inorganic compound 11 is covered with oil over time, and the emulsified oil adsorption effect by electric force is weakened for a certain period of time, but the oil film formed by the captured oil is continuously supplied. Used for processing emulsified oil 12.

This phenomenon is continued until the inside of the oil-water separation material 9 becomes oil-saturated. After the oil-water separation material 9 becomes supersaturated, the large oil droplets 8 which have become larger than the emulsified oil 12 due to aggregation and coarsening are pushed out by water pressure. It separates from the oil-water separation material 9. Coarse oil drop 8
Rises to the water surface due to a specific gravity difference from water (water specific gravity> oil specific gravity) and accumulates in a layered manner, forming a layered oil 13 as shown in FIG.

Since the oil-containing water is supplied upward from below the filter 15 as shown in FIG. 2 (A), the liquid flow is such that the coarse oil droplets 8 can be easily discharged upward. The accumulated laminar oil 13 is drawn out of the oil treatment tank 4 by the oil recovery valve 14 through the oil discharge port 18, and the oil removal is completed.
It should be noted that the dispersed oil and other forms of oil can be separated by this treatment method in the same manner as in the related art.

The oil-water separation material 9 is used by filling it into the filter portion 15. The oil-water separation material 9 may be cut into a shape similar to the bottom area of the filter portion 15, and may be vertically stacked in the filter portion 15 for use. Alternatively, it is also possible to cut into strips, stack and fill them at an arbitrary filling bulk density, and use them. (Example 1) BaSO ₄ was selected as an inorganic compound, and an oil / water separator having a content of 35 wt% was cut into the same shape as the cross-sectional area of the filter portion 15, and then 100 sheets were vertically stacked inside the filter portion 15. I do.

From the oil-containing water inlet 16 below the filter unit 15, the oil-containing water (oil concentration: oil content:
(500 ppm) at a volume flow rate of 10 L / min to perform an oil-water separation treatment.

[0028]

[Table 1]

As the oil-water separation material, a new product having no oil adhesion and an oil-saturated product prepared by artificially absorbing oil to make it oil-saturated are prepared. Was used for a long time to confirm the oil-water separation power when the oil-water separation material became saturated with oil.

As a result of the oil-water separation treatment, as shown in the right column of Table 1, the oil concentration of all oil types was reduced to less than 1/50 of the initial concentration. Example 2 BaSO ₄ was selected as an inorganic compound, an oil-water separator having a content of 35 wt% was formed in a strip shape having a width of 20 mm and a flow of 1000 mm, and the filter portion was filtered at a rate of 0.10 g per cubic meter. Fill 15 Next, the oil-containing water inlet 1 below the filter section 15
From No. 6, the oil-containing water (500 ppm) of the oil shown in Table 2 which was mixed with an ultrasonic wave and a stirrer for 30 minutes and emulsified was passed at a volume flow rate of 10 L / min to perform an oil-water separation treatment.

[0031]

[Table 2]

As the oil / water separation material, a new product having no oil adhesion and an oil-saturated product prepared by artificially absorbing oil and having an oil-saturated state are prepared. Was used for a long time to confirm the oil-water separation power when the oil-water separation material became saturated with oil.

As a result of the oil-water separation treatment, as shown in the right column of Table 2, the oil concentration of all oil types was initially reduced to about 1/50 or less.

[0034]

As described above, according to the present invention, a resin fiber having a three-dimensional network structure is provided in an oil treatment tank, and a large number of protrusions are arranged on the surface of the resin fiber to generate a positive charge in oil-containing water. By installing an oil-water separator equipped with fine particles of inorganic compounds that take on, the emulsified oil that has a negative charge due to interfacial friction with water can be captured by the fine particles of inorganic compounds. Fine emulsified oil can be removed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main configuration of a wastewater treatment apparatus of the present invention.

FIG. 2 is a diagram for explaining the principle of oil treatment by an oil-water separator.

FIG. 3 is a diagram illustrating a configuration example of a conventional wastewater treatment device for oil-containing water using a coalescence method.

FIG. 4 is a view for explaining the principle of oil processing by a conventional coalescence method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Storage tank 2 Oil-containing water 3 Pump 4 Oil treatment tank 5 Coalescer filter 6 Treatment liquid 7 Dispersed oil 8 Coarse oil droplet 9 Oil-water separation material 10 Resin fiber 11 Inorganic compound 12 Emulsified oil 13 Layered oil 14 Oil recovery valve 15 Filter part Reference Signs List 16 oil-containing water inlet 17 treatment liquid circulation port 18 oil discharge port 19 oil-containing water injection valve 20 treatment liquid circulation valve 21 pressure gauge

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C02F 1/40 B01D 17/04 C02F 1/28

Claims (4)

(57) [Claims] 1. A method for treating oil-containing water wastewater, comprising: pumping oil-containing water from a storage soda to an oil treatment tank (lower or bottom portion) via a pump, and passing the oil-containing water to a filter provided inside the oil treatment tank. The oil-containing water that has been pumped is filled by an oil-water separation material composed of resin fibers having a three-dimensional network structure and a plurality of fine particles of an inorganic compound that is positively charged in water and has a three-dimensional network structure. A wastewater treatment method characterized in that oil droplets are forcibly aggregated to coarsen the oil droplets, and the oil content is separated by a difference in specific gravity with water. 2. The pumped oil-containing water is supplied from a lower part of the filter part, passes through the oil-water separator vertically stacked inside the filter from below to above, and is discharged from an upper part of the filter. The wastewater treatment method according to claim 1, wherein the wastewater treatment is performed. 3. A wastewater treatment device for oil-containing water; a storage tank for storing oil-containing water; and a cylindrical or polygonal cylindrical upper surface having a predetermined height and at least one predetermined size having a cylindrical upper surface. A first inlet for supplying the oil-containing water is provided at the center of the bottom surface, and a large number of three-dimensional meshes are arranged inside and protruded on the surface. A filter portion in which an oil-water separator made of resin fibers having fine particles of an inorganic compound having a positive charge in water is filled in the inside of the cylindrical shape; a cylindrical or polygonal cylindrical upper surface portion having a predetermined height Is opened, a second inlet for supplying the oil-containing water to a central portion of the bottom portion, an oil outlet for discharging the separated oil to the upper portion of the cylindrical shape, and a cylindrical or polygonal cylindrical shape. Circulating the processing liquid from which oil was separated at the bottom of the tank to the storage tank An oil treatment tank having a liquid circulation port, and a first injection port at the center of the bottom portion of the filter section engaged (joined, seated, locked, mounted) with the second injection port; A pump for pumping the oil-containing water stored in the storage tank into the filter unit through first and second inlets. 4. The wastewater treatment apparatus according to claim 3, wherein the oil-water separator is vertically filled with the resin fiber having a predetermined thickness in the filter portion.