JP2004097916A - Treatment method for sludge water of ready-mixed concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform a process for dehydrating all of sludge water of a sludge water tank in a short time in a method for dehydrating sludge water containing a cement component discharged from ready-mixed concrete kneading equipment by a dehydrator. <P>SOLUTION: The sludge water of the water surface part of the sludge water tank is sent to the dehydrator to preferentially perform the dehydration treatment of a large amount of sludge water low in the concentration of cement and a high dehydration capacity is put to practical use to perform dehydration treatment in a short time. By filtering a small amount of sludge water high in the concentration of cement, all of the sludge water in the sludge water tank is subjected to dehydration treatment to further shorten a treatment time. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to a method for dewatering a sludge water containing a cement component discharged after collecting aggregates such as gravel and sand from a ready-mixed concrete kneading facility and a process for treating remaining ready-mixed concrete by a dehydrator. is there.
[0002]
[Prior art]
In the ready-mixed concrete kneading facility, sludge water containing cement, such as washing water from the kneading facility and runoff from the ready-mixed concrete, is discharged. In the process of treating raw concrete that has not been used in concrete product factories or construction sites, sludge water containing cement is also discharged after collecting aggregates such as gravel and sand from raw concrete. .
[0003]
The sludge water containing these cement components is temporarily stored in a sludge water tank, sent to a dehydrator such as a filter press, and solidifies the cement components as a dehydration cake to perform a dehydration process to make a stable state. The treated water filtered is stored in a treated water tank and reused as washing water and kneading water in the facility. Excess treated water is adjusted to a pH value or the like and discharged to the outside.
[0004]
As a method of dewatering sludge water, the sludge water in the sludge tank is kept in a static state for a certain period of time, and the cement contained in the sludge water is allowed to settle naturally, and the sludge water in the upper layer where the cement is thin is not directly dewatered. To the treated water tank, and the sludge water in which the lower layer of cement has settled is sent to a dehydrator to be subjected to dehydration treatment, and then sent to the treated water tank.
This is performed in order to shorten the time required for the dewatering process as much as possible and to finish the dewatering process of the sludge water as soon as possible.
[0005]
For example, when sludge water with a cement concentration of 3% is stored in a sludge water tank having a capacity of 60 m ³ and placed in a static state for 3 hours and allowed to settle naturally, about 4/5 of the total amount of sludge water has a cement concentration of 0.1%. Dilute upper layer sludge water is formed, and about 1/5 becomes sludge water precipitated in the lower layer. When the sludge water precipitated in the lower layer is subjected to dehydration treatment and filtered into sludge water having a cement concentration of 0.001%, a sludge water having a cement concentration of 4/5 and a cement concentration of 0.1% and a cement concentration of 1/5 having a cement concentration of 0/5 are contained in the treated water tank. 0.001% of sludge water is mixed, and sludge water with a cement concentration of 0.08% is stored in the entire treatment tank.
However, when discharging the sludge water to the outside of the facility, the cement concentration must be 50 ppm (0.005%) or less, and the above method cannot discharge the sludge water to the outside of the facility. Therefore, it is necessary to dehydrate all the sludge water in the sludge water tank to reduce the cement concentration of all the sludge water.
[0006]
Therefore, in order to discharge the sludge water to the outside of the facility, the entire amount of the sludge water in the sludge tank is sent to a dehydrator, and dewatered to a uniform cement concentration. However, if the treatment is performed so that the sludge water in the treated water tank can be discharged to the outside of the facility with the cement concentration being 0.001%, the sludge water dewatering process takes a long time and is discharged from the facility one after another. It is difficult to perform a dehydration treatment without storing sludge water.
[0007]
[Patent Document 1]
JP-A-7-195099
[Problems to be solved by the invention]
Therefore, in view of the above problems, it is an object of the present invention to provide a method for dewatering sludge water using a dewatering machine, in which the step of dewatering all the sludge water in a sludge water tank is performed in a short time.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a method for treating sludge water containing cement component discharged from a kneading facility for ready-mixed concrete by a dehydrator, the method comprising: Calculate the correlation curve between the treatment amount and the cement concentration of the sludge water, and detect the deflection point on the correlation curve where the dewatering amount of the dehydrator begins to rapidly increase as the cement concentration of the sludge water decreases, It is characterized by comprising a first step of dehydrating sludge water having a cement concentration of the deflection point or less and a second step of dehydrating the sludge water having a cement concentration of the deflection point or more in a sludge water tank.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. FIG. 2 shows a correlation curve between the amount of dehydration treatment per unit time of three types of dehydrators having different treatment capacities of the dehydrators and the cement concentration of the sludge water.
According to the correlation curve A between the amount of dewatering treatment per unit time of the dewatering machine and the cement concentration of the sludge water shown in FIG. 2, when the cement concentration of the sludge water becomes lower than a certain value, the lower the cement concentration of the sludge water becomes, the smaller the dewatering machine becomes. The point a at which the dehydration processing capacity of the is dramatically increased is detected. (Hereinafter, point a on this correlation curve is referred to as a deflection point.) Dewatering of sludge water having a cement concentration of this deflection point a or less can be performed in a short time in a large amount.
[0011]
In the sludge water filtration step, the sludge water is passed through a filter cloth provided in the dehydrator, whereby the cement content is filtered to obtain treated water. The cement component filtered by the filter cloth adheres to the filter cloth, and the adhesion of the cement component to the filter cloth increases by continuing the filtration of the sludge water. Initially, the cement component that adheres to the filter cloth as a thin film gradually adheres to the filter cloth as a thick layer, which hinders filtration of sludge water.
For this reason, when the sludge water having a low cement content is used, the sludge water adheres little to the filter cloth and does not hinder the filtration. On the other hand, when the sludge water having a high cement content is used, the sludge water adheres much to the filter cloth, hinders the filtration, and reduces the amount of dehydration treatment per unit time of the dehydrator.
[0012]
Further, the cement concentration of the sludge water in the water surface portion of the unstirred sludge tank is a value smaller than the cement concentration at the deflection point, since the cement becomes thin even if it is not settled for a certain time due to the natural sedimentation of the cement.
The present invention pays attention to the above points, sends the sludge water on the water surface of the sludge tank to the dehydrator, and preferentially performs a dehydration treatment on a large amount of small-concentration sludge water, taking advantage of the high dehydration treatment capacity for a short time. The sludge water having a high cement concentration is filtered with a small amount to perform a dewatering treatment of the sludge water in the entire sludge tank, thereby further reducing the treatment time.
[0013]
Explaining the deflection point of the correlation curve, in the example of the deflection point a in the correlation curve A of the dehydrator shown in FIG. 2, the tangent to the point on the correlation curve is the value of the cement concentration on the right side of the graph of FIG. In the region, the inclination shows a small angle close to horizontal, which indicates that the dewatering ability does not fluctuate greatly even if the cement concentration fluctuates.
When the cement concentration becomes gradually smaller, the inclination of the tangent becomes a larger angle, and when the inclination of the tangent becomes about 45 °, when the cement concentration becomes lower, the dewatering capacity of the dehydrator dramatically increases. Is obtained.
At the point where the cement concentration becomes smaller than the deflection point a, the inclination of the tangent suddenly becomes a large inclination of 45 ° or more. In these regions, the lower the cement concentration is, the higher the dewatering capacity becomes, and the more efficient the dewatering process becomes. It can be carried out.
The deflection point is located in the vicinity of a 45 ° point which is a neutral point between 0 ° and 90 ° of the inclination of the tangent line at a point on the correlation curve. Changes extremely.
[0014]
Hereinafter, examples of the present invention will be described.
The sludge tank for storing the sludge water discharged from the facility is provided with a water pump for sending the sludge water to the dehydrator. A water absorption pipe that sucks up the sludge water in the sludge tank to the water supply pump is provided from the sludge water tank to the water supply pump, and an intake port provided in the water suction pipe is provided with a float (floating tool), and the water level of the sludge water surface is increased. The intake port is moved up and down to take in the sludge water on the water surface and send it to the dehydrator.
The sludge water tank is provided with a stirring means for stirring the sludge water, and the stirring allows the concentration in the sludge water tank to be all uniform.
The treated water dehydrated by the dehydrator is stored in a treated water tank, reused as washing water and kneading water in the facility, and discharged to the outside after adjusting water quality such as pH value.
[0015]
FIG. 1 shows a flowchart of the dehydration treatment step of the present invention.
In the first step 1 of the dewatering treatment of the sludge water, the sludge water in the sludge tank is not placed in a static state for sedimenting the cement component, and the intake port is provided so as to be located on the water surface, Immediately, the sludge water on the water surface is taken in and sent to the dehydrator. At this time, the stirring means is not operated in order to maintain the state in which the sludge water on the water surface has a low cement concentration, and the stirring of the sludge water is not performed.
By not performing the stirring, the cement concentration of the sludge water on the water surface portion becomes equal to or less than the deflection point a on the correlation curve A, and the dewatering process of the dehydrator has a high dewatering capacity, so that a larger amount of sludge water can be processed in a short time. It becomes possible.
[0016]
For example, when the agitation is not performed in the sludge water having an average concentration of 3%, the cement concentration of the sludge water on the water surface becomes about 0.5% due to the natural sedimentation of the cement. According to the correlation curve A between the dewatering treatment amount of the dehydrator and the cement concentration of the sludge water shown in FIG. 2, the cement concentration at the deflection point a in this graph is about 3%, and the cement concentration of the sludge water on the water surface is 0%. Since 0.5% is a smaller concentration, a high dehydration capacity can be obtained in the dehydrator.
As the dewatering process of the sludge water proceeds, the amount of water in the sludge tank decreases, and the water level decreases. The intake is equipped with a float to keep the sludge water on the surface of the cement with low cement concentration sent to the dehydrator, and even if the water surface fluctuates up and down, the intake moves in accordance with the top and bottom of the water surface. Can be placed on the water surface.
[0017]
As another example of moving the intake port, the position of the water surface is determined using a sensor, and the intake port is moved up and down to the position of the water surface portion by using an electric chamber brochure or a winch, or the position of the water surface is worked. The operator visually checks and manually operates the chamber blow. In addition, in the above example, the intake port is provided in the water suction pipe that sucks up the water supply pump, but without providing a water absorption pipe connecting the sludge water tank and the water supply pump, the water supply pump is provided in the sludge water tank, and the water suction pump absorbs water. The same effect can be obtained even if the water supply pump itself is moved up and down in accordance with the movement of the water surface by using a float or a chamber blow as in the above-mentioned example using the mouth as an inlet.
[0018]
In the second step 2, when the amount of water in the sludge tank decreases, the cement concentration of the remaining sludge water increases, and the cement concentration of the sludge water on the water surface approaches the deflection point a. Will decrease.
Therefore, the sludge water is stirred by the stirring means provided in the sludge water layer to make the cement concentration of the sludge water in the water tank uniform without excessively increasing, and the sludge water is sent to the dehydrator while preventing a decrease in dewatering capacity. Dewater all sludge water.
In addition, stirring the sludge water can also prevent workability deterioration due to solidification of the cement generated due to an increase in the cement concentration and adhesion to the water tank.
[0019]
In each of the correlation curves shown in FIG. 2, the sludge water treatment amount per unit time varies depending on the treatment capacity of each dehydrator, and the cement concentration at the deflection point of each correlation curve varies. This is because there is a difference in the surface area of the filter cloth for filtering the sludge water provided in each dehydrator according to the difference in the processing capacity of each dehydrator. In the correlation curve C of the dehydrator having a large processing capacity, the surface area of the filter cloth is also different. In the correlation curve A of the dehydrator having a large and small processing capacity, the surface area of the filter cloth is also small. For this reason, since the amount of the cement component filtered by the filter cloth differs, the sludge water treatment amount per unit time differs, and the position of the deflection point also differs. For example, the cement concentration at the deflection point a in the correlation curve A of the dehydrator having a processing capacity of 78 L is 3%, and the cement concentration at the deflection point b in the correlation curve B of the dehydrator having a processing capacity of 138 L is 4%. The cement concentration at the deflection point c in the correlation curve C of the dehydrator having a capacity of 230 L is 5.5%, and the numerical value of the deflection point varies depending on the processing capacity of each dehydrator.
[0020]
Through the above steps, the dewatering treatment of the sludge water can be performed on all the sludge water, and the treated water having a low cement concentration can be obtained. In addition, all the sludge water can be dehydrated in a short time.
[0021]
【The invention's effect】
As described above, according to the present invention, since the sludge water in all the sludge tanks is dewatered, treated water having a low cement concentration can be obtained.
In addition, since the sludge water with a low cement concentration is dewatered as the first step of the dehydration treatment, the dehydration treatment capacity of the first dehydration treatment is large, and a large amount of sludge water can be treated. Can respond urgently sometimes.
Similarly, since the initial dewatering amount of the sludge water is large, it is possible to easily cope with sudden generation of the sludge water, and it is possible to reduce the capacity of the sludge water tank as compared with the related art.
[0022]
Furthermore, since sludge water with a low cement concentration is treated in the first step as compared with the conventional dehydration treatment step in which the entire amount is made to have a uniform cement concentration, wear of the machine in the dehydration treatment is prevented and the cement content in the piping is reduced. Adhesion can be reduced.
In addition, since the inlet moves vertically above and below the water surface, the sludge water on the water surface having a low cement concentration is always sent to the dewatering machine, so that the dewatering machine can maintain the initial high dewatering capacity.
[Brief description of the drawings]
FIG. 1 shows a flowchart of a dehydration treatment step of the present invention.
FIG. 2 is a diagram showing a correlation curve between a dewatering treatment amount per unit time of a dehydrator and a cement concentration of sludge water.
[Explanation of symbols]
1 First step 2 Second step

Claims (3)

In a sludge water treatment method in which sludge water containing cement discharged from a kneading facility for ready-mixed concrete is dewatered by a dehydrator, a correlation curve between the amount of dewatering per unit time of the dehydrator and the cement concentration of the sludge water. Calculates, detects the deflection point on the correlation curve where the dewatering amount of the dewatering machine begins to rapidly increase as the cement concentration of the sludge water decreases, and dewaters the sludge water having a cement concentration of the deflection point or less. And a second step in which sludge water having a cement concentration equal to or higher than the cement concentration at the deflection point is stirred and dewatered in a sludge tank. The sludge water treatment method for ready-mixed concrete according to claim 1, wherein a cement concentration of the sludge water at the deflection point is 3 to 6%. 2. The first step, wherein an inlet for feeding the sludge water in the sludge tank to the dehydrator is provided on a water surface portion, and the intake port moves up and down according to the water surface. Of fresh concrete sludge water treatment.

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