JPH0757357B2 - Circulation use method of factory treated water - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for purifying, recycling, and recycling the treated wastewater used for cleaning waste liquid of machined products and pretreatment for surface treatment, and recycling. The present invention relates to a recycling method of factory treated water that can efficiently purify and reuse waste liquid contaminated with chips, oils and fats.

[Prior Art] In a factory for manufacturing automobiles, tractors, etc., it is common to provide a cleaning process for machine parts that have been ground or cut, and also provide a cleaning process before performing various surface treatments such as painting. Is. Among these, for example, regarding the process of cleaning the above-mentioned machine parts, the present applicant has previously filed Japanese Patent Publication No. 59-8434, and has submitted a closed type cleaning device for purifying and reusing waste water after cleaning. FIG. 5 is an explanatory diagram showing an outline of reuse of cleaning water in the machining process.

In FIG. 5, it is assumed that the machine component after processing is conveyed along the arrow A and passes through the positions 21a, 21b, 21c in the conveying direction. Above the 21a to 21c is a nozzle 22a,
22b and 22c are provided, and wash water is jetted from them.
The cleanliness of the wash water does not change at the nozzles 22a, 22b, 22c, but the washing wastewater that drops from the position of 21a is the most polluted due to the order of washing, and the pollution degree decreases toward 21b, 21c and left. Become. Therefore, a partition plate 32 as shown in the figure is provided in the tank 23 that receives the fall of the washing wastewater, and the left side is divided into the washing wastewater diluting chamber B and the right side is divided into the washing wastewater concentrating chamber C,
These chambers B and C are communicated with each other at the bottom of the partition plate 32. It is circulated to the nozzles 22a to 22c through a circulation line 4 provided with a relatively clean cleaning wastewater (hereinafter referred to as “dilution wastewater”) pump 4a, a heating device (not shown) and the like in the dilution chamber B, and is reused. On the other hand, highly contaminated cleaning wastewater (hereinafter referred to as concentrated wastewater) in the concentrating chamber C is sent from the drawing line 5 provided with the pump 5a to the calandria 6 and heated by the high temperature steam supplied from the steam line 11. The steam obtained by this heating has recovered the cleanliness, is further purified through a demister or the like, and is then sent to the condenser 7, stored in the tank 9 as condensed water, and pumped through the line 16 by the pump 16a. After being combined with the diluted wastewater in the circulation line 4, it is reused. On the other hand, the highly polluted liquid (referred to as a concentrated liquid in the figure) further concentrated by the calandria 6 is sent from the discharge line 12 to the combustion furnace 14 and incinerated.

On the other hand, FIG. 4 is an explanatory diagram showing the reuse device of the washing water in the pre-process of the surface treatment, and the points different from the example of FIG. 5 are as follows. That is, the purified water D in the tank 3a is supplied to the treatment tank group 1 in FIG. 4 through the supply pipe 2a, and the waste water E is stored in the tank 3b through the discharge pipe 2b.
It is sent to Calandria 6 as in the illustrated example. Calandria 6
The vapor separated by is condensed and liquefied in the condenser 7 and then stored in the storage tank 24, and a part thereof is supplied to the processing tank group 1 through the bypass line 30 and corresponds to the position 21a in the case of FIG. Used as wash water. The remainder is further purified by the Diamals activated carbon adsorption tower 25 and the ion exchange resin membrane processing tower 26 and then supplied to the tank 3a, which is used as washing water corresponding to the positions 21b and 21c in the case of FIG. To be done.

[Problems to be Solved by the Invention] The method using the Diamals activated carbon adsorption tower 25 and the ion exchange resin membrane treatment tower 26 shown in FIG. There is a drawback in that it needs to be replaced and the production cost of pure water becomes high, and it has been desired to develop a method capable of treating at low cost.

Further, the treated water obtained by the condenser 7 shown in FIG. 5 and supplied from the line 16 has improved quality as compared with the diluted wastewater flowing in the circulation line 4,
Since a large amount of diluted wastewater merges and is mixed, the contaminated cleaning liquid is eventually supplied from the nozzles 22a to 22c, and as a result, the cleaning effect of the parts is reduced and the subsequent processes are adversely affected. Or, it would be very uneconomical to reach the time of total replacement of washing water sooner. Therefore, there has been a need for a method of improving the quality of treated water and diluted wastewater by some means.

[Means for Solving the Problems] The gist of the present invention is that the step of separating and removing the low boiling point oil component in the treated water is carried out by treating the condensed water after evaporation with a submerged combustion device. This has made it possible to eliminate various drawbacks in the conventional adsorption system.

[Operations and Examples] FIG. 1 is a schematic explanatory view showing an apparatus for reusing washing water using the method of the present invention, showing a case of washing wastewater treatment performed as a pre-step of surface treatment, and FIG. Similarly, it shows the case of reuse of cleaning water in the machining process. However, the method of the present invention is not limited to the case of using the above-mentioned exemplified apparatus, and may be a method in which changes are made in accordance with the gist of the preceding and the following.

FIG. 1 is characterized in that the Diamals activated carbon adsorption tower 25 and the ion exchange resin membrane treatment tower 26 in the example of FIG. As shown in FIG. 2 (cross-sectional explanatory view), the details of the submerged combustion device 15 are those in which a submerged burner 17 is provided inside a sealed box body 31, and a fuel gas supply pipe 19 and an air supply are provided. The fuel gas and the air respectively supplied from the pipe 18 are burned, and the generated combustion gas is jetted into the treatment liquid F together with the untreated liquid introduced from the supply pipe 28. Therefore, the treatment liquid F is heated by the heat of the combustion gas and stirred, and the low boiling point oil components and other organic components in the treatment liquid are taken out from the exhaust gas pipe 20 together with the droplets, and these droplets are removed by a demister or the like. After that, it is incinerated by the combustion furnace 14 (see FIG. 1).

Therefore, the low boiling point oil component contained in the treated water evaporated by the Calandria 6 [including MVR (vapor compression type evaporator) and other types of evaporators] in FIG. This can be almost completely removed by the submerged combustion device 15, and the water quality can be applied as the water for cooling the cation electrodeposition membrane in the step before the surface treatment or the cation electrodeposition dip washing water. Table 1 shows the water quality change when the waste water E is separated into the concentrated liquid and the treated water by the calandria 6, and the treated water is purified by the submerged combustion device 15.

Thus, it was found that when the submerged combustion device 15 was used, the residual oil content in the purified water was reduced and the COD was also improved.

FIG. 3 is a schematic explanatory view of a cleaning water reuse device in a machining process using the method of the present invention, and the points different in configuration from the example shown in FIG. 5 are as follows. That is, the submerged combustion device 15 is provided on the downstream side of the treated water tank 9 via the pipe 8, and the branch pipe 27 from the circulation line 4 via the valve 31.
Is characterized in that the branch pipe 27 is connected to the pipe 8. Then, a part of the diluted waste water is mixed with treated water and introduced into the submerged combustion device 15, and the low boiling point oil component in the mixed water is removed while heating the mixed water, and the cleaning aqueous solution supplied to the nozzle 22 is supplied. Improve quality. By doing so, a part of the diluted wastewater is always purified, so that the frequency of replacement can be reduced and the wastewater can be reused efficiently.

In the example shown in FIG. 3, another in-liquid combustion device is used in the discharge line 12.
It is also possible to provide 21 to prevent the components in the liquid from freezing or crystallizing by heating the concentrated liquid, and further to evaporate the liquid components in the liquid to facilitate incineration.

[Advantages of the Invention] According to the present invention, the quality of treated water and washing water condensed through a distillation apparatus such as an evaporator can be efficiently improved, and purification and reuse of waste liquid can be performed at low cost. .

[Brief description of drawings]

1 and 3 are schematic explanatory views showing an example of an apparatus used in the method of the present invention, FIG. 2 is a sectional explanatory view showing an example of an in-liquid combustion apparatus, and FIGS. 4 and 5 are used in a conventional method. It is a schematic explanatory drawing which shows the example of an apparatus. 2a …… Supply pipe, 2b …… Exhaust pipe 13 …… Steam supply line

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C02F 9/00 504 B 7446-4D

Claims (1)

[Claims] 1. An industrial wastewater containing an oily component is subjected to a distillation treatment to be separated into steam and concentrated water, and the obtained steam is condensed and then treated in a submerged combustion device to separate a low boiling point oil content. A method for recycling factory treated water, characterized in that purified water is reused as factory treated water.