JPH08126803A - Control of sedimentation tank - Google Patents

Abstract

PURPOSE: To provide a control method of a sedimentation tank enabling to keep a level of a separation boundary constant by easily detecting concentration of treated waste water, keeping concentration of impurities in the treated waste water constant, detecting the separation boundary formed between the precipitate and the supernatant water by a sensor and discharging the precipitate from the bottom surface. CONSTITUTION: In this sedimentation tank for separating the precipitate 5 and the supernatant water 14 from the process waste water, the control method of the sedimentation tank provided with a concentration sensor 4 under a liquid surface comprises detecting the concentration of impurities floating in the supernatant water by a concentration sensor 4 and informing abnormality of the concentration of the treated waste water discharged from the sedimentation tank.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a settling tank for separating a process waste liquid generated in a process of manufacturing a laminated board or a printed wiring board into a precipitate and a supernatant water.

[0002]

2. Description of the Related Art A large amount of water, an alkaline solution or an acidic solution is used in various steps for manufacturing a laminated board or a printed wiring board. The above-mentioned water, alkaline solution, acidic solution, etc. used once contains aluminum, copper, solder, etc. and is treated as a process waste liquid. Since this process waste liquid cannot be discharged as waste water as it is because it contains the above impurities, it has been necessary to separate it into a liquid portion and a solid portion.

As a separation method, there is a precipitation tank as shown in FIG. This settling tank 13a has an upper intake port 1 of the tank.
The process waste liquid is taken into the settling tank 13a from 0, and the agitator 7a
By injecting the coagulant while stirring and mixing,
Impurities existing in the liquid are aggregated. Impurities in the waste liquid stirred by the stirring blade 7 are promoted to form a precipitate 5,
The sediment 5 separated by sedimentation is accumulated in the lower part of the sedimentation tank 13a because it is surrounded by the partition plate 15 and aggregates to form a separation interface 6 with the supernatant water 14.

Further, as the process waste liquid is taken in, the liquid level 12 of the supernatant water 14 rises, and the supernatant water 14 is discharged from the treated water outlet 11 as treated waste water. At this time, the separation interface 6 also rises in the same manner as the liquid surface 12 of the supernatant water 14 rises. Since the speed at which the separation interface 6 rises is substantially determined by the amount of the process waste liquid taken in, the precipitate 5 is periodically discharged from the bottom of the tank to the storage tank 9 by the pump 8.

However, if the concentration of impurities in the process effluent is high or if the coagulation by the coagulant is poor, the precipitate 5 does not accumulate and does not accumulate in the lower layer of the sedimentation tank, and the supernatant water 14 contains a large amount of impurities. There is a problem that the treated water is discharged from the treated water outflow portion 11 as treated waste water containing a large amount of impurities.

[0006]

The present invention has been made in view of the above circumstances, and its object is to:
The concentration of the treated effluent can be easily detected to keep the impurity concentration of the treated effluent constant, and the separation interface formed by the precipitate and the supernatant water is detected by the sensor, and the precipitate is discharged from the bottom surface to separate the separation interface. The object of the present invention is to provide a method for controlling a settling tank, which can keep the level of the constant.

[0007]

According to a first aspect of the present invention, there is provided a method for controlling a settling tank, wherein a settling tank for separating a process waste liquid into a precipitate and a supernatant water is provided with a concentration sensor below the liquid surface. It is characterized in that the concentration sensor detects the concentration of impurities floating in the supernatant water and notifies the concentration abnormality of the treated wastewater discharged from the settling tank.

The method of controlling a settling tank according to claim 2 of the present invention comprises an optical sensor below the liquid surface of the settling tank,
The optical sensor detects the separation interface between the precipitate and the supernatant water, and when the upper limit is detected, the precipitate is discharged from the bottom surface, and when the lower limit is detected, the discharge is stopped.

[0009]

The method for controlling a settling tank according to the present invention is a settling tank for separating a process waste liquid into a precipitate and supernatant water, and a concentration sensor is provided below the liquid surface, and the concentration sensor floats in the supernatant water. Since it detects the concentration of impurities present, it issues an alarm as a concentration abnormality of the treated wastewater discharged from the settling tank,
The outflow of treated wastewater containing impurities can be notified.

Further, an optical sensor is provided below the liquid surface of the settling tank, and the upper and lower limits of the separation interface between the precipitate and the supernatant water are detected by this optical sensor, and the precipitate is discharged from the bottom of the tank. Therefore, the amount of the sediment accumulated in the lower layer of the sedimentation tank can be kept constant, and the highly concentrated sediment can be discharged to the storage tank.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

[0012]

FIG. 1 is a sectional view of a settling tank according to an embodiment using the method for controlling a settling tank according to the present invention. FIG. 2 is an explanatory diagram of a concentration sensor used in the method of controlling the settling tank of the present invention.

As shown in FIG. 1, an embodiment of a settling tank using the method for controlling a settling tank according to the present invention is as follows:
An intake port 10 formed on the upper side surface of the settling tank 13,
It is composed of an agitator 7a, a partition plate 15, and a pump 8, and a concentration sensor 4 and an optical sensor 3 are arranged so as to be located below the liquid surface.

The stirrer 7a is provided with a stirring blade 7 for stirring the taken-in process waste liquid. Further, as the concentration sensor 4, a light emitting and receiving type laser sensor is used, and the amplifier 2
Is connected to and a signal is sent to the control device. As shown in FIG. 2, the density sensor 4 is composed of a light projecting section 4a, a light receiving section 4b and an amplifier 2, and a constant light 20 is emitted from the light projecting section 4a.
Is emitted to the light receiving portion 4b, but the light emitting portion 4a and the light receiving portion 4b
When the impurity 21 exists between the light receiving element 4b and b, the light receiving amount of the light receiving portion 4b fluctuates, and this value is calculated by the amplifier 2 to obtain the density.

The optical sensor 3 detects the separation interface 6, and is arranged at the upper limit level 6a and the lower limit level 6b in order to control the level of the separation interface 6. The optical sensor 3 is not particularly limited, but a reflection type optical sensor is preferable, and a fiber type sensor whose level can be easily adjusted and which has good water resistance is preferable.

An example of using the above settling tank will be described below with reference to the drawings. First, the process waste liquid is taken into the settling tank 13 inside the partition plate 15 from the upper inlet 10 of the tank. Then, the aggregating agent is injected while stirring with the stirrer 7a, and by stirring, the impurities existing in the liquid are aggregated. Impurities in the waste liquid stirred by the stirring blade 7 are promoted to coagulate, and precipitates 5
Next, it accumulates in the lower layer and forms a separation interface 6 with the supernatant water 14.

The concentration sensor 4 installed near the liquid surface 12 of the supernatant water 14 measures the impurity concentration near the liquid surface 12 of the supernatant water 14 and calculates the concentration using the value measured by the amplifier 2. If the concentration is high, the intake of the process waste liquid is stopped to prevent the liquid surface 12 from rising, and an alarm of abnormal concentration is issued. Further, if the concentration is low, the process waste liquid is further taken in, the liquid surface 12 of the supernatant water 14 is raised, and is discharged from the treated water outflow portion 11 as treated waste water.

Further, as the precipitation of impurities progresses, the separation interface 6 of the precipitate 5 rises. The level of the separation interface 6 is detected by the optical sensor 3, and when the upper limit level 6a is reached, the amplifier 1 connected to the optical sensor 3 operates the pump 8 installed at the bottom of the settling tank 13 to settle the precipitate. 5 is discharged to the storage tank 9.

By discharging the precipitate 5 to the storage tank 9, the level of the separation interface 6 decreases, and when the separation interface 6 becomes lower than the lower limit level 6b, the pump 8 is stopped by the amplifier 1 to stop the discharge of the precipitate.

As described above, the separation interface 6 between the precipitate 5 and the supernatant water 14 can be adjusted to a desired level by repeatedly stopping the operation of the pump 8.

[0021]

As described above, according to the method for controlling a settling tank of the present invention, by measuring the concentration of supernatant water below the liquid surface of the settling tank, the concentration of treated wastewater is kept constant and impurities It is possible to prevent the outflow of the treated wastewater containing a high concentration of. Moreover, since the separation interface of the aggregated impurities can be detected and the level of this separation interface can be controlled to a desired position, the aggregation separation can be automatically performed continuously.

[Brief description of drawings]

FIG. 1 is a sectional view of a settling tank according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a concentration sensor used in the present invention.

FIG. 3 is a sectional view of a conventional settling tank.

[Explanation of symbols]

 1 Amplifier 2 Amplifier 3 Optical Sensor 4 Concentration Sensor 5 Precipitate 6 Separation Interface 7 Stirring Blade 8 Pump 10 Intake Port 11 Treated Water Outflow Portion 12 Liquid Level 13 Precipitation Tank 14 Clear Water

Claims (2)

[Claims] 1. A settling tank for separating a process waste liquid into a precipitate and a supernatant water, a concentration sensor is provided below the liquid surface, and the concentration sensor detects the concentration of impurities floating in the supernatant water. A method for controlling a sedimentation tank, which comprises notifying an abnormal concentration of treated wastewater discharged from the sedimentation tank. 2. An optical sensor is provided below the liquid surface of the settling tank, the optical sensor detects the separating interface between the precipitate and the supernatant water, and when the upper limit is detected, the precipitate is discharged from the bottom surface, and the lower limit is set. The method for controlling a settling tank according to claim 1, wherein the discharging is stopped when the above is detected.