JPS599234B2 - Treatment method for oil-containing wastewater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cleaning wastewater containing dispersed oil, emulsified oil, or a water-insoluble solvent using an oil adsorbent. The present invention relates to a method for purifying oil-containing wastewater using an oil adsorbent containing crude linter as an essential component.

Currently, regulations regarding the degree of pollution of wastewater are being tightened in order to improve the environment.

On the other hand, the amount of wastewater that requires purification is large and its types are diverse. In other words, there are a wide variety of oils and other substances contained in wastewater from petroleum refining, synthetic chemistry, mechanical work, food chemistry factories, gas stations, etc., and especially when oils form stable emulsions, they can be highly concentrated. Oil is contained in wastewater. Although various methods for purifying such oil-containing wastewater have been attempted, a method that is adaptable to the diversity of wastewater and requires low treatment costs has not yet been realized, and therefore, sufficient purification of wastewater has not been implemented. This may result in excessive wastewater treatment costs for companies. Therefore, there is a need to establish a cleaning method that is low in treatment and construction costs and can be applied to a wide range of wastewater amounts, oil content types, and concentrations. It provides law.

Conventionally, the method for treating wastewater containing emulsified oil is to absorb the oil with an oil adsorbent, and then separate and recover the oil from the adsorbent by incinerating the oil adsorbent or by squeezing, centrifuging, extraction, etc. is used.

Most oil adsorbents suitable for such purposes are made of fibers with a large surface area, and among them, synthetic fibers made of hydrocarbon polymers such as polypropylene, which have a large oil adsorption capacity, are mainly used.

However, oil adsorbents made of these synthetic fibers have a low ability to retain low viscosity oil, and incineration has problems because the amount of heat generated is too large.

Depending on the type of solvent contained in the wastewater, there are various disadvantages in practical use, such as the inability to maintain the structural shape and the high unit cost. The inventors of the present invention have conducted extensive studies on oil adsorbents that have high oil adsorption capacity, are resistant to solvents, are available at low cost in large quantities, and are not likely to cause secondary pollution when incinerated or otherwise disposed of after use. It was discovered that unrefined crude linta collected from cottonseed contains an appropriate amount of oil and fat, and has a high degree of water repellency and oil adsorption ability due to the high porosity inside the fibers. Rinter completed an invention (patent application 146597/1989) regarding an oil adsorbent made by mixing and molding thermoplastic synthetic polymers or semi-synthetic polymers, and confirmed that it could be used as a water surface floating type oil adsorbent. The present invention relates to the treatment of oil-containing wastewater based on the fact that an oil adsorbent containing crude linter as an essential component acts extremely effectively not only on oil floating on the water surface but also on oil emulsified and dispersed in water. be.

The method for treating oil-containing wastewater of the present invention will be explained in detail below.

When treating wastewater where the oil content forms relatively unstable emulsified oil droplets and the oil content is relatively low in concentration, put the fleece of a crude linter in a container made of net and throw it into the wastewater. Alternatively, by passing wastewater through a column containing coarse linter fleece, oil can be adsorbed and separated to obtain water with a low oil content.

When treating wastewater in which the oil content forms stable emulsified oil droplets and the oil content is relatively high in concentration, it is possible to use pine or ice-land molded with the fibers of a crude linter arranged in a substantially constant direction. Oil can be adsorbed and separated by forming a permeable layer and passing wastewater so that the fiber axis direction of most of the fibers coincides with the flow direction of the wastewater. In this case, only crude linter is used as the fiber. It can also be molded and used as a perforation layer, but 10 to 30% by weight of thermoplastic synthetic fibers or semi-synthetic fibers or both, or 5 to 30% by weight based on the crude linter.
A mixture of 10 to 50% by weight of refined natural fibers or both of them in a total amount of 10 to 50% by weight and molded can be used as the perforation layer.

In the case of a wastewater layer consisting almost only of coarse linter, the coarse linter has extremely high water repellency, so wastewater does not permeate into the flow layer well, and if wastewater is injected in this state, channeling may occur. However, it may not be possible to purify wastewater effectively. Refined natural fibers, such as purified lint, purified lint, and refined pulp, are highly hydrophilic, and when a small amount of this is dispersed and mixed with crude lint, it has the effect of promoting uniform permeation of wastewater into the filtration layer. There is.

On the other hand, synthetic fibers and semi-synthetic fibers such as polypropylene and cellulose acetate are lipophilic, but even though their hydrophilicity is extremely low, their water repellency is lower than that of crude linter, so even when they are mixed with crude linter. According to the new findings of the present inventors, surprisingly, it has the effect of sufficiently promoting permeation of the contained wastewater. When this synthetic fiber or semi-synthetic fiber is thermoplastic, it can be used as a thermal adhesive molding binder for mats or strands mainly made of coarse linter, and at the same time it can also have the effect of preventing chain ringing.

When used as a binder, if it is less than 10% by weight, the strength of the formed overlayer will be low, and if it is more than 30% by weight, a decrease in the amount of oil adsorption and problems during incineration will occur.

The method for preparing the oil-containing wastewater permeation layer material used in the present invention can be, for example, the following method. That is, the fibers, which are mainly coarse linters, are arranged in parallel with the production direction and piled up, formed into a mat, and tightly wound in a spiral shape with the longitudinal direction as the axis, forming a cylinder, which is perpendicular to the long axis. Cut it at appropriate intervals to obtain a disc-shaped molded product. One or more of these are stacked and inserted into a cylindrical column. Alternatively, a disk-shaped molded product having substantially the same cross section as the column may be obtained by direct molding. When the amount of molded articles packed in a column is the same, the efficiency of separation by filtration is better if several molded articles are stacked and the corresponding packing amount is filled than when one molded article is packed. Further, when a filter paper having a pore diameter of about 10 to 70 microns, particularly preferably a filter paper manufactured by Rinter, is used in combination at the middle or lower end of the stack of these molded products, a particularly excellent oil separation effect is exhibited. This is because when oil-containing wastewater is treated with hydrophilic fiber filtration paper, which has a pore size approximately the same as the emulsion particle size of the emulsified oil droplets, the emulsion breaks down on the surface of the filtration paper, and the oil droplets coalesce, promoting oil-water separation. This is to be done.

The synthetic fibers or semi-synthetic fibers used as a binder for adjusting water repellency and used in the crude linter of the present invention are fibers having melt adhesive properties such as polypropylene, polyethylene, ethylene vinyl acetate copolymer, ethylene propylene copolymer, There are fibers such as cellulose acetate.

In particular, fibers of ethylene propylene copolymer and ethylene vinyl acetate copolymer are preferred.

In addition, purified natural fibers for adjusting water repellency include purified linter,
Refined pulp, refined lint, etc. are available, and viscose manufactured fibers can also be used. Incorporation of these fibers for adjusting water repellency has the effect of reducing the resistance to permeation of oil-containing wastewater and, in turn, lengthening the life of the perforation layer.

In addition to the above-mentioned melt-adhesive fibers, binders for molding include powders of the above-mentioned polymers, or emulsion-type or solution-type adhesives for nonwoven fabrics such as thermally crosslinkable acrylic ester copolymers and vinyl acetate copolymers. is used. The perforation paper for breaking the oil droplet emulsion may be any sheet with pores of about 10 to 70 microns and made of a hydrophilic substance, such as linter paper, general cellulose, partially acetalized polyvinyl alcohol, etc. Fuchikashi paper is used.

The present invention will be explained in detail below with reference to Examples, but the present invention is of course not limited to the Examples.

Example 1 Water to which 130 PPi0 of heavy oil A was added was stirred using a homomixer at 7000 rpm for 1 minute and forcefully dispersed, and this was used as a model wastewater, and the cleaning ability of the oil adsorbent was measured.

The results are shown in Table 1. The model wastewater described above corresponds to wastewater containing relatively unstable dispersed oil droplets at a low concentration. As a wastewater treatment method, mats shown in Table 1 are placed on a support provided in a porcelain column with a diameter of 130 mm, and this is used as a filtration layer to collect 1000 cm of model waste water.
c was passed. The content of treated water is “JISKOlO2
The measurement was conducted in accordance with the n-hexane extractable substance measurement method described in ``Factory Waste Water Test Method''. As a comparison sample, a commercially available oil adsorbent was similarly cut and packed into a column.
The composition of the oil adsorbent is shown below. Crude linter O: Crude linter 100 (f) Crude linter A: Crude linter 90%, ethylene, propylene, copolymer fiber (hereinafter abbreviated as ElPl) 10% Crude linter B: Crude linter 80%, ElPl2O% Crude linter C : Crude linter 70%, ElPl3O% Crude linter mat The thickness and density of the oil adsorbent material is 7f per 1cTi! This is the measured value under a load of

Example 2 Three types of model wastewater were treated with an oil adsorbent.

That is, in the same manner as in Example 1, A heavy oil 800 PFI 210
Model wastewater containing 600 PyB of cleaning oil (No. 2 kerosene) was prepared, and 1000 cc of waste water was treated in the same manner as in Example 1 with a filter layer made of an oil adsorbent.

The results are shown in Table 2.

In the table, coarse linter mat/linter paper means that linter paper (manufactured by Daicel, basis weight 227y) is placed on the support in the column.
r/Lice thickness 0.07 CITL) Density 0.32 Ir/Cl)
The filtration layer is made by laying a layer of coarse linter mat on top of it. Coarse linter mat/Linter paper/
Rough linter mat/linter paper is a filtration layer made by layering linter paper and mat on top of the above combination. (FeSO42OPPm) in the table shows model wastewater treated with a filter layer after adding 20 ppm of ferrous sulfate as an oil droplet coarsening aid.

(The same applies to Table 3) The results in Table 2 are FeSO42
By using OPPm, the oil concentration in treated water is reduced to 2p.
pm to 0.5PyB, and 1.2ppm to 0.7pp
It is shown that the number decreased to m. Example 3 Three types of model wastewater were treated with an oil adsorbent.

That is, in the same manner as in Example 1 or 2, lubricating oil (Idemitsu Kosan Daphne Mechanical Oil 75) 900PPf1 cutting oil (Idemitsu Kosan Daphnicut TA-35) 900PF, engine oil (Nippon Oil PAN-xSElOW-4)
0) Model wastewater containing 700 ppm was prepared and treated in the same manner as in Example 1 or 2.

The model wastewater used in this example corresponds to wastewater in which emulsified oil droplets are relatively stable and the oil concentration is high.

The measurement results are shown in Table 3.

The results in Table 3 show that, as in Table 2, by adding FeSO42OPPm to the model wastewater, the oil concentration in the treated water was significantly reduced in all cases.

Note: Crude linter E: Composition of 80% crude linter and 20% refined linter.

Example 4 Model wastewater containing a non-aqueous solvent was prepared and treated with an oil adsorbent.

That is, a model wastewater containing 2,812 ethylbenzenes was prepared in the same manner as in Example 1, and treated with a filter layer made of an oil adsorbent.

Claims (1)

[Scope of Claims] 1. A method for treating wastewater containing linter, which comprises cleaning wastewater containing crude linter using an oil adsorbent containing crude linter as an essential component. 2. The method for treating wastewater containing wastewater according to claim 1, which uses an oil adsorbent formed by mixing 10 to 30% by weight of thermoplastic synthetic fibers and/or semi-synthetic fibers with crude linter and molding the mixture. 3. Claim 1 using an oil adsorbent formed by mixing 5 to 30% by weight of refined natural fibers with crude linter and molding the mixture.
Method for treating contained wastewater as described in section. 4 10 to 50% by weight of purified natural fibers and thermoplastic synthetic fibers and/or semi-synthetic fibers in total based on crude linter
A method for treating wastewater containing wastewater according to claim 1, which uses an oil adsorbent formed by mixing and molding. 5. Oil-containing wastewater according to claim 1 or 2 or 3 or 4, wherein the fiber axes of the crude linter are arranged in a substantially constant direction, and the oil-containing wastewater is made to flow in the direction of the fiber axes. Processing method. 6. A method for treating oil-containing wastewater using a combination of an oil adsorbent containing crude linter as an essential component and a filter paper. 7. The method for treating oil-containing wastewater according to claim 6, which uses a filter paper and an oil adsorbent in which 10 to 30% by weight of thermoplastic synthetic fibers and/or semi-synthetic fibers are mixed with crude linter. 8. Claim 6, which uses a filter paper and an oil absorbent mixture of crude linter with 5 to 30% by weight of refined natural fibers.
Method for treating contained wastewater as described in section. 9. The method according to claim 6, in which an oil adsorbent in which a total amount of 10 to 50% by weight of refined natural fibers, thermoplastic synthetic fibers and/or semi-synthetic fibers are mixed with respect to crude linter and filter paper is used in combination. Method for treating oil-containing wastewater. 10 Claim 6 or 7, in which oil adsorbents containing crude linter as an essential component are stacked so that their fiber axes are aligned, and a filter paper is inserted in the middle and/or at the lower end.
The method for treating oil-containing wastewater according to paragraph 8 or paragraph 9.