JPH10323698A - Waste water treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and costlessly decompose and remove coloring maters. SOLUTION: Electrodes or waste water is heated on electrolyzing the waste water. That is, solid foreign materials are filtered in a screen tank 2 and waste water is electrolyzed by use of electrodes heated at a specified temperature by external heat energy, in the primary electrolytic treatment tank 3. And then flocs in the waste water are settled in the primary settling tank 4. And further, the waste water is electrolyzed by use of electrodes heated at a specified temperature by external heat energy, in the secondary electrolytic treatment tank 5 and flocs in the waste water are settled in the secondary settling tank 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for treating industrial wastewater, and more particularly to a method for treating wastewater using electrolysis and thermal energy, which is suitable for treating wastewater containing pigments such as dyes and pigments.

[0002]

2. Description of the Related Art Generally, wastewater treatment methods include a chemical treatment method using chemicals, a biological treatment method using microorganisms, a physical treatment method such as electrolysis or electrooxidation, and these methods. Can be cited.

[0003] Physical and chemical treatment methods include a method using an oxidizing agent, an adsorption method using activated carbon, electrodialysis, and an ion exchange method. The method using an oxidizing agent has the advantage that the oxidizing agent reacts well with the organic substances in the wastewater and does not generate secondary pollutants, but it is expensive and the maintenance cost of the processing equipment is not small, so the price is low. And is not normally used except for special purpose wastewater treatment.
In addition, the adsorption treatment method using activated carbon has a high effect of removing general contaminants and odors, but has a low effect of removing dyes and pigments such as dyes, and the price of activated carbon itself is high. Over time, the activated carbon has to be regenerated, resulting in increased maintenance costs. Further, the electrodialysis method and the ion exchange method also have a disadvantage that they are not suitable for treating a large amount of wastewater. For this reason, recently, an electrolysis method, which is a physical treatment method, has been widely used as a wastewater treatment method.

[0004]

However, the conventional electrolysis method has a long reaction time, consumes a large amount of electrode plates, and generates a large amount of sludge. Costs are high. Although small-scale wastewater treatment is possible, large-scale wastewater treatment is uneconomical because facility costs are high, treatment capacity is low, and a large amount of electric energy is consumed.

[0005] Among the industrial wastewaters, in the dyeing wastewater,
Treatment of common dyes with dye or pigment components is particularly better than improving pH (hydrogen ion index), BOD (biological oxygen demand), COD (chemical oxygen demand) and SS (suspended matter) It is valued. Conventionally, a method using both biological treatment and chemical treatment has been widely used for the treatment of this dyeing wastewater. However, in such a method, there is a limit in treating wastewater containing a dye having an azo bond such as a dye or a pigment, and the efficiency of removing the dye is still unsatisfactory. In addition, a general electrolytic method can treat a small amount of waste liquid, but requires a reaction time of 30 minutes to 1 hour or more in an electrolytic cell, and a large amount of waste liquid is required because the decomposition performance of a dye is deteriorated. There is a problem that it is difficult to process.

Accordingly, the present invention solves the disadvantages of the above-described conventional wastewater treatment methods, and in particular, the disadvantages of the conventional treatment methods for wastewater containing dyes such as dye wastewater and pigment wastewater.
It is an object of the present invention to provide a wastewater treatment method which has a high dye removal efficiency and is improved from the prior art.

[0007]

SUMMARY OF THE INVENTION The present inventor greatly improves the dye removal efficiency of dyeing wastewater by using a method of applying thermal energy using steam or waste steam to the method of treating wastewater by electrolysis. I found that I can do it.

The present inventors have discovered that the efficiency of decomposition of pollutants can be increased by applying an appropriate amount of heat during the electrolytic treatment in the electrolytic method. The contaminants themselves have activation energies, and become unstable and agglomerate or destroy only when more energy is applied externally. The present invention uses such properties to remove contaminants.

[0009] The pollutants contained in the wastewater have their own charge and activation energy. In the case of treating a contaminant by an electrolysis method, energy corresponding to the substance is required in order to destabilize the contaminant by electrostatic repulsion and to dissociate and remove a dye bond. In the electrolysis method, heat energy is generated from the electrodes after a certain reaction time has passed. However, the thermal energy generated from this electrode alone is not enough to effectively improve the efficiency of wastewater treatment. The present inventor adds to the electrolysis method such that waste steam and / or heat of the steam is applied from inside and / or outside of the electrolysis tank to increase the temperature of the wastewater to be treated, whereby the electrolysis treatment is performed without heating. The present inventors have found that the efficiency of processing is dramatically improved as compared with the case where only the above is performed, and have completed the present invention.

When the heating in the waste liquid treatment method by electrolysis is performed by electricity, not only is the power consumption large, but also the electrode plate is corroded by ionization, and it is difficult to maintain and repair the electrode plate. There is a disadvantage that the efficiency reduction is added to the operation cost.

On the other hand, a method of applying thermal energy to wastewater is to wind a steam tube around the outside of the electrolytic cell and heat the electrolytic cell by passing steam or waste vapor through the tube of the tube. , Steam or waste steam can be directly introduced into the inside of the electrolytic cell to heat cold waste water (16 to 20 ° C.) which flows in at the initial stage. Can be kept low.

The heating temperature of the waste liquid is desirably 60 to 120 ° C., and the operation is performed so that the temperature becomes appropriate according to the wastewater to be treated.

The method for treating a dye by electrolysis to which the present invention is applied is to heat an electrolytic cell with steam or waste steam, or to apply heat energy by directly introducing steam or waste steam into the electrolytic cell to apply heat energy to the wastewater. It improves the efficiency of decomposition of chemical substances. As a result, according to the present invention, the azo covalent bond in the wastewater that could not be destroyed by the conventional technique was destroyed, and the efficiency of dye removal could be increased. Examples of the decomposition reaction of a dye containing an azo bond are shown in the following reaction formulas (1) and (2). The azo bond in the dye is dissociated as shown in the reaction formula (Chemical formula 1) and further oxidized, so that it is finally decomposed and removed as an oxide as shown in the reaction formula (Chemical formula 2). In the formula (x), x is 2 or 3, and y = 2x + 38.

[0014]

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[0015]

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[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a process for treating dyeing wastewater to which the present invention is applied. First, the wastewater to be treated is stored in the storage tank 1 and collected, and then the solid contaminants are primarily filtered by the screen in the screen tank 2. Thereafter, the wastewater is sent to the primary electrolytic treatment tank 3 and subjected to electrolysis while being heated to 80 ° C. or higher by waste steam or steam. As for the heating, the electrolytic treatment tank 3 may be externally heated by waste steam or steam, and the steam or waste steam is directly introduced into the electrolytic treatment tank 3 to heat the electrode plate or waste water in the electrolytic bath. Is also good. The processing conditions in the primary electrolytic processing tank 3 are, for example, using a DC 12 V, 15 A power supply, using a nickel-based electrode plate as the electrode plate, and a processing time of 5 minutes to
It can be 10 minutes. Under these treatment conditions, wastewater in most general printings takes 5 to 7 minutes, and wastewater containing pigments and / or dyes having an azo bond forms flocs after about 10 minutes, and about 80% of the dye It was observed to be removed.

Next, the wastewater subjected to the primary electrolysis treatment is sent to the primary sedimentation tank 4 to settle and / or float the flocs, to remove sediment or suspended matter and to discard the wastewater. And subject to electrolysis and heat treatment under the same conditions as the primary electrolyzer 3 to treat the remaining 20% of the dye. Thereafter, the wastewater treated in the secondary electrolytic tank 5 is sent to the secondary sedimentation tank 6, and the precipitated sludge is discarded. I do.

The treatment time (ie, the residence time of the wastewater in the electrolytic cell) can be adjusted by adjusting the amount of wastewater supplied to the electrolytic cell. Further, the temperature of the wastewater can be adjusted by the supply amount and temperature of steam for heating and the flow rate of the wastewater in the electrolytic cell (that is, the amount of wastewater supplied to the electrolytic cell).

Next, the results of the treatment analysis of the dyeing wastewater treated by the above-described method will be shown. The wastewater to be treated is process wastewater from Korea Chemical Co., Ltd. (located in Korea) and is treated under the conditions shown in Table 1 below, and the dye removal efficiency is measured by the spectrophotometric method (platinum-cobalt standard method) Was measured by Table 2 shows the results. In addition, the electrolysis was performed by adding a small amount of a polymer flocculant after conducting an experiment with source water without adding an electrolyte.

[0020]

[Table 1]

[0021]

[Table 2]

From the analysis results shown in Table 2, it can be seen that the dye removal efficiency according to the present example is 80 to 90% or more, which is very excellent.

[0023]

Industrial Applicability The present invention relates to a method for treating industrial wastewater by electrolysis, in which wastewater or steam is used to heat an electrolytic cell or an electrode plate in the electrolytic cell during the electrolytic treatment to produce wastewater. Add heat energy to increase wastewater treatment efficiency. Thus, according to the present invention, the pigment of the hardly degradable dyeing wastewater, which has been difficult with the conventional wastewater treatment technology, can be efficiently removed.

According to the method for treating industrial wastewater using electrolysis and heat energy of the present invention, the treatment efficiency in dye removal of dyeing wastewater, which was not able to obtain sufficient treatment efficiency with the prior art, is greatly improved. Therefore, the operation time is reduced as compared with the conventional method. Further, the present invention can be implemented by adding a simple thermal energy supply equipment to a conventional electrolysis apparatus, so that the equipment installation cost for implementation is low, and the operation cost is also low,
Very economical. The invention can also be applied to the treatment of large amounts of wastewater.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a process for treating dyeing wastewater according to the present invention.

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Claims (6)

[Claims] 1. A primary filtration step for removing solid foreign matter by filtering wastewater in a screen tank, and introducing the filtered wastewater into a primary electrolytic treatment tank and heating the wastewater to a predetermined temperature by external heat energy. A primary electrolysis step of electrolyzing contaminants in the introduced wastewater using the electrode plate thus formed to form flocs; and a primary precipitation step of removing flocs from the wastewater that has undergone the primary electrolysis, Wastewater that has undergone the primary precipitation stage is introduced into a secondary electrolytic treatment tank, and contaminants in the introduced wastewater are electrolyzed to form flocs using an electrode plate heated to a predetermined temperature by external thermal energy. A secondary electrolysis step, and a secondary precipitation step for removing flocs from the wastewater that has passed through the secondary electrolysis step. . 2. The method according to claim 1, further comprising a second filtration step of filtering the wastewater having undergone the second precipitation step through an activated carbon filter or a sand filter.
A method for treating dyeing wastewater or pigment wastewater as described in the above. 3. The primary electrolysis and secondary electrolysis steps include: heating the electrolysis tank with waste steam or steam;
2. The method according to claim 1, wherein the temperature of the wastewater in the electrolytic treatment tank is maintained at 60 to 120 [deg.] C., and the wastewater is electrolyzed in the electrolytic treatment tank for 5 to 10 minutes and discharged.
A method for treating dyeing wastewater or pigment wastewater as described in the above. 4. The primary electrolysis and the secondary electrolysis steps include introducing waste steam or steam into the electrolytic treatment tank to maintain the temperature of the wastewater in the electrolytic treatment tank at 60 to 120 ° C. 2. The method for treating dyeing wastewater or pigment wastewater according to claim 1, wherein the wastewater is electrolyzed in the electrolytic treatment tank for 5 to 10 minutes and discharged. 5. A wastewater treatment method comprising the step of electrolyzing wastewater in an electrolytic cell, wherein the electrolytic cell is heated by externally supplying energy.
A wastewater treatment method comprising electrolyzing contaminants in wastewater at a temperature of 0 to 120C. 6. An energy source of the energy supplied from the outside is waste steam or steam, and the heating of the electrolytic cell supplies the waste steam or vapor to a pipe wound around an outer peripheral portion of the electrolytic cell. The wastewater treatment method according to claim 5, wherein the method is performed.