JPH043280B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a treatment device for wastewater containing fluorine and phosphorus, and particularly to a treatment of wastewater containing fluorine and phosphorus, which is treated by a two-step reaction process. Regarding equipment.

[Background of the Invention] As a method for efficiently removing fluorine and phosphorus from wastewater, there is a method that includes two reaction steps. There are methods for treating wastewater containing elements.

The treatment method according to Japanese Patent Publication No. 53-43743 consists of a first step in which insoluble substances produced by reacting fluorine in wastewater with calcium ions and phosphate ions at pH 3.5 to 7 are separated from water. , a second step of adjusting the treated water from the first step to a pH of 9 or higher and separating the generated insoluble materials, and returning the insoluble materials separated in the second step to the first step. This is how it was done.

FIG. 1 shows a conventional example of an apparatus for carrying out this treatment method, in which raw water is introduced into a first reaction tank 11 by a pump 10, and a pipe 1
Slaked lime and acid are supplied from 3 and 14, respectively, and the pH is 3.5 ~
The reaction takes place in step 7 and an insoluble substance is produced. This insoluble substance is separated from the liquid in the first sedimentation basin 15 and extracted from the bottom thereof. The supernatant liquid is sent to the second reaction tank 21, slaked lime is added through the pipe 22, and a reaction is carried out under conditions of pH 9 or higher to produce an insoluble substance. Next, it is introduced into the second sedimentation tank 23, where it is separated into solid and liquid, and the supernatant liquid is discharged as treated water.
The precipitate is extracted through the pipe 24 and transferred to the first reaction tank 1.
It will be returned to 1. In the figure, 16 and 25 are PH meters,
The pH in the reaction vessels 11 and 21 is detected.

Therefore, in this conventional device, the amount of chemical injection (slaked lime addition amount) that should be added at the maximum load when the raw water flow rate, fluorine concentration, and phosphoric acid concentration are maximum is set, and the amount of chemical injection is Slaked lime is added in conjunction with the raw water pump. That is, in the first reaction layer 11, a certain amount of slaked lime is always added, and the pH is 3.5 to 3.5.
The amount of acid added is adjusted in accordance with the detected value of the PH meter 16 so that the pH value becomes 7. Also, in the second reaction tank 21, a certain amount of slaked lime is always added. PH total 25
is used for pH monitoring.

As mentioned above, this amount of slaked lime corresponds to the maximum load, so in non-maximum load conditions, slaked lime is added in excess, and acid is also wasted as a result. .

To prevent wasteful consumption of such drugs,
In the past, workers constantly measured the quality of raw water, the amount of water, and the PH, and the valves 17, 18, and 2 were adjusted accordingly.
6 had to be adjusted, which caused problems in terms of labor costs and reliability.

[Object of the Invention] The object of the present invention is to solve the problems of the above-mentioned prior art, and to provide wastewater containing fluorine and phosphorus, in which the amount of chemicals added is always appropriate and the quality of the treated water is extremely stabilized. The purpose of this invention is to provide a processing device.

[Structure of the invention] In order to achieve this object, the fluorine-containing material of the present invention
Phosphorus-containing wastewater treatment equipment reacts fluorine in raw water with calcium ions and phosphate ions in a first reaction tank, separates it into solid and liquid, and then introduces it into a second reaction tank to raise the pH and react. In a treatment device for wastewater containing fluorine and phosphorus, which separates solid and liquid after
Detecting the flow rate of raw water, fluorine concentration, and PH of the first reaction tank, and calculating and adding the water-soluble calcium compound and PH adjuster to the first reaction tank based on these detected values, The phosphoric acid concentration of the liquid introduced into the second reaction tank and the PH in the second reaction tank are detected, and based on these detected values, the optimum amount of PH adjuster to be added to the second reaction tank is calculated and added. It is structured like this.

[Embodiments of the invention] Examples will be described below with reference to the drawings.

FIG. 2 is a system diagram of an apparatus for treating wastewater containing fluorine and phosphorus according to an embodiment of the present invention, in which the same or equivalent members as those in the apparatus of FIG. 1 are indicated by the same reference numerals.

In this embodiment, raw water is supplied from the introduction pipe 30 to the first
Slaked lime and acid are introduced into the reaction tank 11 and added through pipes 13 and 14. Then, air for stirring is blown from the bottom of the tank from the blowing pipe 19 to stir the mixture, and the reaction is carried out at a pH of about 3.5 to 7. The reaction liquid is separated into solid and liquid in the first solid-liquid separation tank 15, the precipitate is extracted from the bottom, and the supernatant water is sent to the second reaction tank 21 through the pipe 33.

Slaked lime is added to the second reaction tank 21 from a pipe 22, stirred by stirring air blown from a blowing pipe 29, and reacted in a basic range of about PH9 or higher. The reaction liquid is subjected to solid-liquid separation in the second solid-liquid separation tank 23, and the supernatant water is discharged from the pipe 27 as treated water and sent to a neutralization process as required. In addition, the precipitate is transferred from the pipe 24 to the first reaction tank 1.
It will be sent back to 1. Incidentally, excess precipitate is extracted from the system through piping 28. In the figure, 41 and 43 are mechanisms for dissolving slaked lime in water and feeding it to the pipes 13 and 22, and are comprised of a slaked lime storage tank, a dissolving tank, a feeding pump, and the like. Further, 42 is an acid liquid feeding mechanism,
It consists of an acid storage tank, dilution tank, feeding pump, etc.

The introduction pipe 30 is equipped with a flow meter 31 and a fluorine meter 3.
2 is installed to detect the flow rate and fluorine concentration of raw water. In addition, the first solid-liquid separation tank 15 and the second
A phosphoric acid meter 3 is installed in the piping 33 connecting to the reaction tank 21.
4 is provided to detect the phosphoric acid concentration of the liquid (first treated water) introduced into the second reaction tank 21.

These flowmeter 31, fluorine meter 32, phosphoric acid meter 3
4, and the first and second reaction tanks 11,
The detected values of the PH meters 16 and 25 provided in 21 are input to the calculation unit 51 of the calculation controller 50, and
Based on these input values, the optimal amounts of slaked lime and acid to be added are calculated and output to the control section 52. Control unit 5
In step 2, the opening degrees of the valves 17, 18, and 26 are adjusted so as to achieve the calculated optimum addition amount.

In the present invention, slaked lime to the first reaction tank 11,
The amount of acid added depends on the raw water flow rate, fluorine concentration, and
Calculated based on the pH in the reaction tank. The amount added to the second reaction tank is calculated based on the phosphoric acid concentration of the first treated water and the pH in the second reaction tank (and the raw water flow rate if necessary).

In the first reaction tank 11, fluorine and phosphoric acid components in the raw water react with calcium ions to generate insoluble substances. Further, the precipitate returned from the second solid-liquid separation tank contains calcium and phosphoric acid, and these are also involved in the reaction and reused as sources of calcium and phosphoric acid. In cases where the phosphoric acid concentration in the wastewater is low, a means (not shown) for adding a phosphoric acid compound to the first reaction tank 11 is provided in addition to this return sludge to reduce the phosphoric acid concentration in the first reaction tank. You may try to do more.

The calcium compound added to the first reaction tank may be any water-soluble one, and in addition to slaked lime,
Calcium chloride, calcium oxide, calcium nitrate, etc. may also be used.

The amount of calcium compound added is slightly larger than the reaction equivalent required to produce calcium fluoride.

When adding a phosphoric acid compound to the first reaction tank 11, the phosphoric acid compound may be one that generates phosphate ions in water, such as a phosphate salt, or crude phosphoric acid. The amount of phosphate ions present is determined by the amount of residual phosphate ions in the first treated water relative to the amount of residual fluorine in the first treated water (supernatant liquid of the first solid-liquid separation tank 15 sent to the second reaction tank 21). It is preferable that the reaction equivalent amount or slightly more than that required to produce fluorine calcium phosphate remains.

The pH in the first reaction tank 11 is about 3.5 to 7, preferably about 4 to 6.

If the pH is less than about 3, the residual amount of fluorine in the treated water increases, and if the pH is more than about 7, the residual amount of fluorine increases and phosphate ions tend to precipitate, which is not preferable.

As a result of the above-described first reaction, most of the fluorine in the wastewater becomes calcium fluoride, and a portion becomes calcium fluorine phosphate, producing insoluble matter.

The supernatant liquid (first treated water) of the first solid-liquid separation tank 15 is sent to the second reaction tank 21, and slaked lime is added through the pipe 22 to adjust the pH to about 9 or more. In addition to slaked lime,
Sodium hydroxide, potassium hydroxide, etc. can also be used.

In the second reaction tank 21, there is no need to add a calcium compound as long as calcium ions in a reaction equivalent amount to phosphate ions remain in the first treated water. (not shown) may be provided. In that case,
By adding slaked lime as in the above example, both the objectives of pH adjustment and calcium addition can be achieved. Second
By raising the pH to 9 or higher in the reaction tank 21, the trace amount of remaining fluorine reacts with phosphate ions and calcium ions and becomes insolubilized, and the amount of fluorine that flows out into the treated water becomes extremely trace. Further, excess phosphate ions react with calcium ions to form calcium phosphate, which becomes an insoluble substance. This insoluble matter and the above-mentioned fluorine insoluble matter are separated into a second solid-liquid separation tank 23.
Co-precipitation occurs, and trace amounts of insoluble fluorine are efficiently precipitated. For sedimentation separation of insoluble substances, a commonly used flocculant may be added to promote sedimentation.

The sludge produced by settling in the second solid-liquid separation tank 23 is returned to the first reaction tank 11 in this embodiment. This sludge contains calcium and phosphoric acid, and by returning this sludge, the amount of calcium ions and phosphate ions added to the first reaction tank 11 can be reduced. In addition, piping 24 or 28
A sludge return amount adjusting means may be provided in the sludge return amount adjusting means, and this may be controlled by the arithmetic controller 50.

To reduce the amount of residual fluorine in the final treated water,
It is desirable to increase the amount of phosphate ions as much as possible in the reaction in the second reaction tank, but by returning the sludge, the amount of phosphate ions in the first treated water will increase, so the amount of fluorine in the final treated water will be reduced. Can be made in trace amounts. Note that, for this purpose, a means (not shown) for adding phosphoric acid to the second reaction tank 21 may be provided.

Since the device shown in FIG. 2 is an embodiment of the present invention,
The present invention is not limited to the apparatus of the above embodiment.

For example, the precipitate in the second solid-liquid separation tank 23 may be discharged without returning to the first reaction tank 11.

Further, in the above embodiment, the output value of the PH meter 16 is inputted to the calculation unit 51, but the PH adjuster adjusts the amount of PH adjuster added from the pipe 13 based on the output value of the PH meter 16.
A separate regulator may also be provided.

In addition, in the above embodiment, the amount of medicine added is adjusted by adjusting the opening degree of the valve, but it may be adjusted by other adjustment methods, for example, by changing the discharge amount of the chemical liquid feed pump. Furthermore, in addition to the sedimentation type solid-liquid separation tank, a filtration type or centrifugal type solid-liquid separation device may be used, and a stirrer rotationally driven by an electric motor may be used as stirring means for the reaction tank. good.

Furthermore, in order to detect the raw water introduction amount, the rotation speed of a pump for feeding raw water to the reaction tank may be detected, and the pump discharge amount (raw water feed amount) may be determined from this rotation speed. In addition, when an intermediate pump is provided between the first solid-liquid separation tank 15 and the second reaction tank 21, the discharge amount of this intermediate pump and the PH meter 2
5 and the phosphoric acid meter 34, the amount of the drug added to the second reaction tank may be calculated.

[Effects of the Invention] As detailed above, the fluorine/phosphorus-containing wastewater treatment device of the present invention is designed to control the amount of chemicals added such as PH regulators and calcium salts in accordance with the raw water load. The amount of medicine added is always maintained at the optimum value. Therefore, there is no need to add excessive chemicals, reducing treatment costs and reducing the amount of sludge generated.

Since the reaction in the reaction tank is carried out under optimal conditions, the quality of the treated water is stabilized and fluorine and phosphorus do not exceed the quality standards of the treated water.

Therefore, the reliability of the device is high.

Labor saving can be achieved.

Various excellent effects such as these can be achieved.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a conventional device, and FIG. 2 is a system diagram of an embodiment device. 11... First reaction tank, 15... First solid-liquid separation tank, 16, 25... PH meter, 21... Second reaction tank,
23...Second solid-liquid separation tank, 31...Flowmeter, 32
...Fluorine meter, 34...Phosphate meter, 50...Arithmetic controller.

Claims (1)

[Claims] 1 Water-soluble calcium compound addition means, first pH
a first reaction tank having a regulator addition means and a first PH meter; a first solid-liquid separation means for receiving the reaction liquid from the first reaction tank; a second PH regulator addition means and a second PH meter;
a second reaction tank into which the liquid is introduced from the first solid-liquid separation means; a second solid-liquid separation means which receives the reaction liquid from the second reaction tank; a fluorine meter for detecting the fluorine concentration of the raw water; a phosphate meter for detecting the phosphoric acid concentration of the liquid introduced into the second reaction tank; Calculate the amount of PH adjuster and water-soluble calcium salt necessary to maintain the PH within a predetermined range and carry out the reaction based on the detected values of the raw water flow rate detection means, the fluorine meter, and the first PH meter. At the same time,
PH required to maintain the PH of the second reaction tank within the specified range
a calculator for calculating the amount of the regulator to be added based on the detected values of the phosphate meter and the second PH meter; A controller for controlling a first PH adjuster addition means and a second PH adjuster addition means.