JPH0523673A - Method and device for treating organic waste water - Google Patents

Abstract

PURPOSE:To effectively decompose an organic component of high concentration in an organic waste water by providing a spiral passage to outside direction from a central part and by providing a composite electrode arranging an anode, consisting of a soluble anode and insoluble anode, and cathod alternately in the central part introducing the organic waste water. CONSTITUTION:The composite electrode consists of two piece of the insoluble anode 14 extending to the diameter direction from the organic waste water introducing opening 12 as a center, two piece of the soluble anode 15 arranged at a right angle to the insoluble anode and four piece of the cathod 16 arranged between the adjacent insoluble anode 14 and the soluble anode 15. The organic waste water is fed into the electrolytic vessel 11, and when power is supplied between both electrodes, the organic waste water is in contact with the insoluble anode 14 to decompose the organic component. The decomposed organic component is floculated with the particulate generated by dissolution of the soluble anode 15 and is coagulated and sedimented. The organic waste water passes in the spiral passage 17, in which the particulate is sedimented furthermore, to become a clear treated waste water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating organic wastewater having a relatively high concentration to efficiently decompose organic components in the organic wastewater.

[0002]

2. Description of the Related Art With the development of various industries and improvement of domestic life, the amount of organic wastewater containing organic components is increasing. As these organic wastewaters, there are washing wastewater, dyeing wastewater, rice washing wastewater, car washing wastewater, etc., which are treated as follows. For example, in various printing processes such as corrugated board printing, highly concentrated cleaning wastewater is generated (SS
Order, COD value of 10,000 mg / l or more, chromaticity is opaque), and wastewater treatment is required to meet the legal regulations regarding discharged water quality regulations for environmental protection. Conventionally, discharged raw water is aggregated with lime → filtration (sludge removal) →
Polymer coagulation → sedimentation (sludge removal) → activated carbon adsorption [→ oxidizer treatment (eg sodium hypochlorite treatment)] → discharge treatment or raw water → activated sludge treatment → sedimentation (sludge removal) → activated carbon adsorption [ → Oxidizer treatment (for example, sodium hypochlorite treatment)] → Discharging is performed in this order. In this process, although it can be removed to some extent as SS in the case of using a normal treatment equipment, it does not meet the standards for discharged water quality In many cases, the COD value is around 100 mg / liter, and if it is to be removed up to around 10 mg / liter, enormous cost and large equipment are required. Furthermore, at the present time, it is necessary to add a strong oxidizing agent such as sodium hypochlorite at the time of discharge, and the limit of treatment of high-concentration organic wastewater by the conventional process is becoming clear. Processing has become a serious problem in the printing industry and the like.

Further, the dyeing industry develops with the development of the textile industry, and wastewater is an essential step in the dyeing industry, and the amount of wastewater such as dyeing wastewater increases in proportion to the amount of products. This dyeing waste water also needs to be discharged after processing such as decomposition of its organic components in the same manner as the cleaning waste water. Moreover, in the dyeing factory, a large amount of wastewater is discharged together with the fiber waste, and therefore the SS value, COD, and BOD value are generally high. Furthermore, in these dyeing steps and the washing steps accompanying them, there are many pasty substances and surfactants. Often used and chemically synthesized, these substances add to the complexity and complexity of wastewater treatment.

The treatment of domestic sewage such as human waste, bath effluent and laundry effluent is entrusted to the terminal treatment plant and is not a general concern. However, for example, rice bran juice discharged at home is an organic wastewater with a considerably high concentration, and the total amount discharged from each household is enormous. It can also be said that it is undigested and more difficult to treat than excrement from digestive processes such as human waste. There are rice washing wastewater for sake brewing and rice washing rice drainage for lunch boxes that are equivalent to domestic rice bran soup, and these are also produced as a large amount of organic wastewater. If this waste water for washing rice is stored or immediately discharged, it will be fermented under normal conditions momentarily, and a foul odor will be generated, and the pollution will be extremely advanced. If the pollution is advanced, further treatment will be difficult. At present, the activated sludge method is used to treat SS such as rice sewage wastewater, but the large amount of SS and the increase in load due to the progress of fermentation require a huge device. Has the drawbacks of.

With the development of private cars, car washing on a company scale represented by gas stations has been carried out, and the amount of car wash drainage has also increased considerably. As a characteristic of this type of car wash drainage, fats and oils such as wax are overwhelmingly larger than SS components such as sand dust, and a detergent is used for washing and removing these, and the car wash drainage contains a large amount of organic components. Organic wastewater is discharged. The treatment of the car wash wastewater is only a simple oil-water separation using an oil-water separator, and most of it is currently discharged. In each of these organic wastewater, the organic component in the organic wastewater is often a chemically synthesized high molecular weight organic compound, and these are substances that are decomposed or purified by self-cleaning action like natural materials. Absent. In order to decompose such a high molecular weight organic compound, at present, a batch system is adopted which is a combination of chemical operation unit processes (single operation).

In this batch system, a unit process is selected each time according to the component composition, properties, amount, etc. of the organic waste water based on the activated sludge method. The activated sludge process is relatively effective for low-concentration organic wastewater, but the high-concentration organic wastewater of percent order in terms of COD, that is, tens of thousands of mg / liter, has too much load and a large economic burden. Moreover, the device is inevitably getting bigger. In the lime coagulation operation that is sometimes used as a pretreatment for the activated sludge method, the sludge generated is difficult to filter and the sludge amount becomes very large. As a result, there remain major problems in sludge treatment methods and securing treatment sites. Even if the high-concentration organic wastewater of COD value of percent order can be removed by the activated sludge method up to, for example, about 100 mg / liter, residual organic components, fine particles, or substances not involved in the reaction are colored. It remains in the colloidal organic wastewater, which may interfere with the decolorization of the organic wastewater.

Further, in the activated sludge method, a complicated operation such as adding a coagulant to improve treatment efficiency and clearing a regulation value, sedimentation and concentration, filtering a supernatant, and adsorbing the filtrate on activated carbon is carried out. May be added, and the concentration of various salts may increase during discharge, resulting in a property not suitable for discharge. In order to solve these drawbacks of the activated sludge method, a method has been proposed in which organic wastewater is electrochemically treated to oxidize and decompose organic components. However, with this electrochemical treatment method, especially in the case of low-concentration organic wastewater, decomposed substances are suspended or it is difficult to remove by filtration for ultrafine particles, and separate steps such as adding chemicals are required. It has been pointed out that the disadvantages of the prior art, such as the increase in cost and the increase in size of the device, cannot be solved sufficiently as necessary.

[0008]

It is an object of the present invention to provide a method for treating organic wastewater capable of effectively decomposing the organic components of the organic wastewater without increasing the cost and increasing the size of the apparatus, which are the drawbacks of the prior art. And to provide a device.

[0009]

According to the present invention, firstly, in a method of treating organic wastewater with an electrolytic cell having an anode and a cathode to decompose organic components in the organic wastewater, the organic wastewater is soluble in the anode. A method for treating organic wastewater, characterized in that an anode and an insoluble anode are used, and secondly, a composite in which an organic wastewater inlet is installed and an anode and a cathode composed of a soluble anode and an insoluble anode are alternately arranged. The organic wastewater is characterized by comprising a central portion provided with an electrode, and a spiral flow path having an outlet for the treated organic wastewater provided at a tip portion outward from the central portion. It is a processing device.

The present invention will be described in more detail below. In the present invention, the organic wastewater is electrochemically treated to decompose (or alter) the organic components in the organic wastewater by a redox reaction to purify the organic wastewater. When an electric current is applied between electrodes having a certain potential difference, electrons are exchanged between the electrodes and the reaction substance to generate unstable active species such as radical ions, and then a chemical reaction continues to complete the reaction.
Therefore, the electrochemical treatment is first of all resource-saving because it requires almost no materials other than the substances involved in the reaction, such as oxidizing agents and reducing agents, and secondly, it is easy to downsize, simplify or automate the device. Therefore, it is energy-saving because most of the electric power used is used for the required purpose, and fourthly, it is pollution-free because it does not use an oxidizing agent or a reducing agent in the oxidation reduction as described above. It has various characteristics such that it does not require sludge treatment or is greatly reduced.

The decomposition of the organic components in the organic waste water according to the present invention also follows the law of electrochemistry, and the electrochemical treatment is a pollution-free process that can be performed by a clean reagent called "electron". Most of the drawbacks of the prior art can be solved by advancing a difficult reaction or easily advancing an economically disadvantageous reaction at low cost. In the usual electrochemical treatment by electrolytic reaction, decomposition and deterioration of organic components occur due to anodic oxidation, and an insoluble anode such as platinum or lead dioxide is used as the anode. In the decomposition of organic components using these insoluble anodes, the decomposed organic components become fine particles and float in the treatment liquid, and even if organic components such as colored colloids in organic waste water are efficiently decomposed. The decomposition product cannot be easily separated, and it is not an effective method for treating organic wastewater.

In the present invention, while effectively utilizing the decomposing ability of the organic component of the insoluble anode, a soluble anode such as iron, aluminum and carbon is used in combination with the insoluble anode, whereby the color is decomposed by the insoluble anode. It is characterized in that an organic component such as a colloid is flocculated with the fine particles generated by the dissolution of the soluble anode, and its flocculation, that is, its precipitation or settling is promoted and deposited as a solid which is easy to filter. For the soluble anode and the insoluble anode that can be used in the present invention, the conventionally known materials may be used as they are, and the electrode substrate having a flat plate shape, a cylindrical shape, a porous shape or the like can be used without limitation. As mentioned above, the insoluble anode is used for decomposition of organic components and the soluble anode is used for floc formation, and there is an optimum current density for each application, but it is optimal by adjusting the surface area of each anode. The current density of the insoluble anode can be set to 1 to 5 A /
The range of dm ² is 0.2 to 1 A / dm ^{2 for} the soluble anode. Since the soluble anode is for forming flocs and is dissolved and the weight thereof is reduced with the lapse of processing time, when the soluble anode is dissolved by electrochemical treatment and the floc forming ability is decreased, it may be appropriately replaced.

The both anodes may be arranged in any manner, but it is desirable to arrange them so that they are alternately arranged with the cathode which is the counter electrode, and that both anodes are mixed almost uniformly. For example, both anodes including the cathode are arranged. It can be arranged radially or parallel to each other. The method of the present invention may be carried out by a so-called batch process or a transient process, and may be carried out by using the device of the present invention described later or another device.

The device of the present invention has an inlet for organic waste water and has a central part in which a composite electrode in which such an insoluble anode and a soluble anode and a cathode are combined is installed, and in order to achieve miniaturization of the device. A spiral flow path is connected to the central part of the device having this composite electrode, and the flocs generated by the composite electrode are allowed to settle in this flow path, or a filtering device is installed at an appropriate place in the flow path to remove the flocs. After that, the treated organic waste water can be discharged from the tip of the flow path. Therefore, in the device of the present invention, the organic wastewater that is raw water is added to the inlet of the central portion and the organic wastewater is automatically treated by energizing between the anode and the cathode. Alternatively, it is possible to discharge the treated clear organic wastewater, which has been filtered and meets the normal discharge water quality standard, out of the system from the tip of the flow path. In order to prevent discharge from the tip of generated flocs without individually installing unit processes such as an electric treatment tank, a reaction tank and a sedimentation tank, it is possible to achieve the objective by a simple method such as installing a baffle plate. It is possible to easily improve the clarity of waste water. Before the electrochemical treatment of the organic waste water according to the present invention, an acid or an alkali may be added to adjust the pH so that impurities in the organic waste water are easily aggregated.

The present invention will now be described in more detail with reference to the accompanying drawings, but the present invention is not limited thereto. FIG. 1 is a schematic view illustrating an electrolytic cell equipped with a composite electrode that can be used in the method of the present invention. One flat plate insoluble anode 1 made of platinum or lead dioxide, or a platinum base metal oxide coated on a base material such as titanium, and two flat plate soluble anodes 2 made of iron, aluminum, etc. The insoluble anodes 1 are connected in parallel so as to be located in the center, and three cathodes 3 made of nickel plates or the like are installed between the anodes 1 and 2 and to the side of the soluble anode 2 on the right side. 3 are connected in parallel with each other, and the insoluble anode 1, the soluble anode 2 and the cathode 3 constitute a composite electrode.

The composite electrode thus connected is immersed in the organic waste water 5 in the box-shaped electrolytic cell 4 and the organic components in the organic waste water 5 are brought into contact with the insoluble anode 1 by applying an electric current between both electrodes. Then, the decomposition product is decomposed by anodic oxidation, and the decomposition product is brought into contact with the soluble anode 2 to form flocs together with the fine particles generated by the dissolution of the soluble anode 2 to promote aggregation,
Settles on the bottom plate of the electrolytic cell 4. The electrolytic cell of FIG. 1 is a so-called batch type treatment apparatus, and the treated organic waste water is taken out from the electrolytic cell 4, clarified by performing filtration and the like, and then discharged, and the organic component is again stored in the electrolytic cell. The organic waste water containing is supplied and the treatment is continued.

FIG. 2 is a transverse sectional view showing an example of the device of the present invention, and FIG. 3 is a vertical sectional view taken along the line AA of FIG. At the center of the electrolytic cell 11 having a substantially cylindrical appearance, an organic wastewater inlet 12 is formed on the bottom surface, and the organic wastewater supplied from the inlet 12 is agitated by a stirring blade 13 near the inlet 12. After being sufficiently agitated, it contacts the radially extending composite electrode. The composite electrode comprises two insoluble anodes 14 arranged so as to extend diametrically around the inlet 12 and the insoluble anode.
Two soluble anodes 15 arranged so as to extend diametrically around the inlet 12 in the direction perpendicular to the four, and four cathodes 16 arranged between the adjacent insoluble anodes 14 and the soluble anodes 15.
And consists of. A spiral flow path 17 is integrally connected to the central opening of the electrolytic cell body where the composite electrode is installed, and in the illustrated example, a double flow path is formed around the central part. The organic waste water that has passed through the flow path 17 is discharged to the outside of the system from an outlet 18 at the tip of the flow path 17. Further, in the illustrated example, a baffle plate 19 is installed in the flow path 17 inside the double flow path 17 to inhibit the flow of flocs aggregated or settled by the composite electrode to promote the settling and A filter 20 is installed at the tip of the filter 17 to filter the generated flocs and remove the flocs from the treated organic wastewater. The flow path 17 from the central portion of the electrolytic cell body 11 to the outlet 18 is formed so that the bottom surface thereof gradually descends as shown in FIG.

When the organic waste water is introduced from the organic waste water inlet 12 into the electrolytic cell main body 11 having the above-mentioned structure and the two electrodes are energized, the organic waste water is discharged in the same manner as in FIG. The organic component is decomposed by contacting with 14, and the decomposed organic component is flocculated with the fine particles generated by the dissolution of the soluble anode 15 to promote aggregation and sedimentation. As shown in FIG. 2, the organic wastewater having the flocs goes from the central portion to the treated organic wastewater outlet 18 through the spiral flow path 17. Since the flow path 17 from the central part of the electrolytic cell body 11 to the outlet 18 is inclined downward, the flow rate per unit area is reduced to promote floc sedimentation, and the baffle plate 19 further sediments. And a treated organic wastewater that is clear can be obtained. The flocs that have aggregated or settled are filtered by the filter 20 to sufficiently clarify the treated organic wastewater, and then discharged from the outlet 18 to the outside of the system.

[0018]

EXAMPLES Next, examples of the method for treating organic waste water according to the present invention will be described, but the examples do not limit the present invention. Example 1 Organic wastewater was treated using the electrolytic cell shown in FIG. As insoluble anodes, use two platinum-coated titanium plates of 500 mm in length and 250 mm in width, and 500 m in length as soluble anodes.
One aluminum plate having a length of m and a width of 250 mm was used, and four aluminum plates having a length of 500 mm and a width of 250 mm were used as cathodes. Each electrode was connected in the same manner as in FIG. 1 and placed in the electrolytic cell. Navy blue printing ink wastewater was used as the organic wastewater. This drainage is stored in an underground water tank, and 1.5 m ³ /
It is supplied to an isoelectric treatment tank at a rate of time, 0.7 kg of oxalic acid is added per 1 m ³ of waste water in the isoelectric treatment tank for pH treatment, and then the waste water is further electrolyzed at a rate of 1.5 m ³ / hour. The solution was supplied to the bath and a current was passed at a current density of 1 A / dm ² for transient electrochemical treatment. The floc-formed wastewater was taken out of the electrolytic cell and filtered, and then the COD value was measured to be 16 mg / liter. The filtered water was colorless and transparent, and the chromaticity was 0 and the turbidity was 0.

Example 2 Dyeing wastewater of towels was used as organic wastewater, two lead dioxide electrodes of 500 mm in length and 250 mm in width were used as insoluble anodes, and aluminum of 500 mm in length and 250 mm in width was used as a soluble anode. One plate is used, and the cathode is 500 mm long and horizontal
Uses four 250 mm SUS304 sheets with a current density of 1.5 A
The electrochemical treatment of the organic waste water was carried out in the same manner as in Example 1 except that / dm ² was used. C after filtering flocs
The OD value was less than 20 mg / liter, the filtered water was colorless and transparent, and the chromaticity was 0 and the turbidity was 0.

Comparative Example 1 The same organic waste water as in Example 1 stored in the underground storage tank of Example 1 was introduced to the above-ground treatment tank and 20 k per 1 m ³
g lime, 1.5 kg PAC (polyaluminum chloride)
And 0.1 kg of a polymer flocculant were added to remove the generated sludge, and then introduced into a settling tank to allow the flocculate to settle. Further, the waste water was introduced into a filter press type filter to filter flocs, and then treated with activated carbon. The treated effluent was clear pink with a COD value of about 300 ppm, a chromaticity of 30, and a turbidity of 50.

Comparative Example 2 Organic drainage under the same conditions as in Example 1 except that the insoluble anode of Example 1 was used instead of the soluble anode (three insoluble anodes were used and no soluble anode was used). Was treated, the wastewater after treatment was a transparent pink color, and COD
The value was 60 ppm, the chromaticity was 30 and the turbidity was 50.

[0022]

The method of the present invention is characterized in that a soluble anode and an insoluble anode are used together as an anode when the organic waste water is electrochemically treated to decompose the organic components (claim 1). In the electrochemical treatment according to the method of the present invention, which is different from the usual electrochemical treatment, the organic component decomposed by the insoluble anode is effectively used together with the fine particles dissolved from the soluble anode while effectively utilizing the resolution of the organic component of the insoluble anode. It can be flocculated to promote its aggregation, precipitation or sedimentation, and be deposited as a solid which is easy to filter. Therefore, the drawback of the treatment of organic wastewater by the conventional electrochemical treatment, that is, it is difficult to separate the colored colloidal substance, etc., which is generated by the fine particles generated by the decomposition of the organic component from the organic wastewater, is solved. It is suitable for the treatment of colored organic wastewater which produces a small amount of fine particles. Moreover, since the treatment occurs according to the laws of electrochemistry, there is no problem of contamination of the treated organic wastewater due to the use of oxidizing agents or reducing agents, and it is possible to treat the organic wastewater at low cost without worrying about the occurrence of pollution. it can.

Further, the device of the present invention includes a central part in which a composite electrode in which an anode and a cathode composed of a soluble anode and an insoluble anode are alternately arranged is installed, and a spiral flow path extending outward from the central part. (Claim 2), when the organic wastewater is treated using the apparatus, not only the decomposition of organic components and formation of flocs can be sufficiently performed as in the case of the method of the present invention,
The treated organic wastewater containing almost no flocs can be discharged to the outside of the system by promoting the flocculation or sedimentation of the flocs in the flow channel, and the flow channel has a spiral shape, thus increasing the size of the apparatus. It can be prevented as much as possible. Further, in the apparatus, at least one of a filtering device, a slant plate and a sedimentation tank can be installed instead of installing individual unit processes in a spiral flow path (Claim 3), whereby the flocs are filtered. And can be almost completely removed from the treated organic wastewater. Further, when the height of the bottom surface of the spiral flow path is lowered from the central part toward the tip part to form an inclination (claim 4), the cross-sectional area of the flow path through which the treated organic wastewater flows Is gradually increased and the flow velocity is decreased, so that sedimentation of the flocs is promoted, and an increase in treatment efficiency can be intended.

[Brief description of drawings]

FIG. 1 is a schematic view illustrating an electrolytic cell equipped with a composite electrode that can be used in the method of the present invention.

FIG. 2 is a cross-sectional view showing an example of the device of the present invention.

FIG. 3 is a vertical sectional view taken along the line AA of FIG.

[Explanation of symbols]

1 ... Insoluble Anode 2 ... Soluble Anode 3 ... Cathode 4 ... Electrolytic Tank 5 ... Organic Wastewater 11 ... Electrolytic Tank 12 ... Organic Wastewater Inlet 13 ... Agitation Wing 14
..Insoluble anode 15 ... Soluble anode 16 ... Cathode 17
・ ・ ・ Flow path 18 ・ ・ ・ Organic wastewater outlet 19 ・ ・ ・ Baffle plate 20 ・ ・ ・ Filter

Claims (4)

[Claims] 1. A method for decomposing organic components in an organic wastewater by treating the organic wastewater with an electrolytic cell having an anode and a cathode, wherein a soluble anode and an insoluble anode are used. How to treat organic wastewater. 2. A central portion having an organic waste water inlet and a composite electrode in which an anode and a cathode composed of a soluble anode and an insoluble anode are alternately disposed, and a tip portion facing outward from the central portion. An apparatus for treating organic wastewater, comprising: a spiral flow path provided with an outlet for the treated organic wastewater. 3. The organic wastewater treatment device according to claim 2, wherein at least one of a filtering device, an inclined plate and a settling tank is installed in the spiral flow path. 4. The organic wastewater treatment device according to claim 2, wherein the height of the bottom surface of the spiral flow path is lowered toward the tip.