JP5542561B2 - Flocculant addition management method - Google Patents

Description

  The present invention relates to a flocculant addition management method, and specifically relates to a technique that allows a flocculant to act at low cost and without waste according to turbidity.

  For example, in a construction site involving rock excavation, various earthworks, and dredging, muddy soil may be mixed with nearby water currents and rainwater to form muddy water. Since such muddy water cannot be discharged as it is into a river or the like, it is necessary to appropriately reduce the turbidity in a sand settling facility. There is a technique of adding various flocculants as a technique for reducing turbidity.

  As such a technique, for example, in a processing apparatus comprising an agitation tank that takes in raw water and adds a flocculant and stirs, a flocculant feeder that adds a flocculant to the agitation tank, and at least one precipitation tank, For the flocculant feeder, the amount of flocculant added can be adjusted based on the measured value by the measuring device that measures the turbidity of raw water and the measured value by the measuring device that measures the turbidity of treated water A polluted water treatment apparatus (see Patent Document 1) characterized by having an adjustment function has been proposed.

JP 2005-34821 A

  As in the prior art, if the turbidity of both raw water and treated water is measured, for example, if the measured turbidity value of the treated water is fed back to the determination process of the flocculant addition amount, the turbidity of at least two locations Issues such as increased cost due to the introduction of measuring equipment, and the need to perform feedback control based on two measured values (raw water and treated water), making it difficult to control the amount of flocculant added Is left. In addition, the nature of rocks and earth and sand, etc., vary depending on the location, and the nature of the generated muddy water changes as the construction progresses. These changes in turbid water need only be within the normal turbidity range that can be handled by the conventional technology, but if the turbidity suddenly increases and exceeds the normal high turbidity range, the conventional technology can handle it. There is also concern that it will not be possible. On the other hand, in order to cope with such a situation, if the amount of the flocculant added is always kept larger than the required amount, there is an inconvenience that the flocculant is wasted and the turbidity of the treated water is generated.

  Then, this invention aims at provision of the technique which can make a flocculant act without waste according to turbidity at low cost.

The flocculant addition management method of the present invention that solves the above problems is based on a geological map related to a construction target location, and collects soil samples for each region of different geological properties in the construction target location, , Creating a plurality of turbid water having different turbidity from each other,
For each turbid water with different turbidity created for each region, measure the amount of flocculant added to reduce the turbidity to a predetermined standard, and estimate the correlation between the turbidity and the necessary amount of flocculant for each region. A step of setting a correlation equation estimated for each region with respect to a control device that controls the addition mechanism of the flocculant;
Set the said correlation equation for the corresponding region including the current work target portion of the respective areas to the control unit, by the control device, the turbidity of the turbid water to be the processing target that put the current work target portion Obtain from a turbidimeter, apply the turbidity to the correlation equation for the relevant region, determine the required amount of flocculant, and control the addition mechanism so that the required amount of flocculant is added to the turbid water. A process of performing;
It is characterized by including.

  According to such a technique, a correlation equation between the turbidity and the necessary amount of the flocculant is estimated in advance for the construction target location, and the flocculant addition amount matching the raw water turbidity based on this correlation equation Can be controlled. In order to estimate the correlation equation, turbid water is prepared for a sufficiently wide range of turbidity (for example, 0 <turbidity ≦ 16000 ppm), and the amount of flocculant required for such turbid water is measured. As a correlation formula, a necessary addition amount for a wide range of turbidity can be specified.

  In addition, a turbidity measuring device may be introduced for the measurement of raw water, and the amount of flocculant added is controlled based on the measured turbidity of raw water, which complicates the equipment configuration. In terms of cost, it tends to be cheaper than before. Further, even when turbidity suddenly increases, the necessary coagulant addition amount can be determined without a large excess or deficiency by the above-mentioned correlation formula taking into consideration a wide turbidity range, and can be appropriately handled. . That is, it can be said that there is little concern that waste due to the addition of an excessive flocculant, a white turbidity of treated water, and the like will occur. Therefore, according to the present invention, the flocculant can be allowed to act at low cost and without waste according to the turbidity.

Furthermore, even if the nature of the ground and ground to be constructed vary greatly depending on the location and a sudden increase or decrease in turbidity occurs, it is necessary to use the correlation equation estimated in advance for each region. Therefore, it is possible to appropriately determine the amount of flocculant to be added without undue deficiency. That is, even if the geological properties and the like differ depending on the location, it can be said that there is little concern that waste due to excessive addition of the flocculant, the clouding phenomenon of the treated water, and the like will occur.

Further, in the flocculant addition management method, a step of collecting a sample of earth and sand at a construction target location, comparing the sample with the geological map, and identifying a corresponding region including the current construction target location among the respective regions When,
Setting the correlation equation for said identified corresponding area to the control unit, by the control device, the turbidity of the turbid water to be the processing target that put the current work target portion obtained from the turbidity meter, the turbidity Determining the required amount of flocculant by applying a degree to the correlation equation for the corresponding region, and controlling the addition mechanism so that the determined required amount of flocculant is added to the turbid water;
May be included.

  According to such a technique, for a place to be actually constructed, a corresponding area in a natural ground or the like is specified according to the geological property, and the necessary amount of the flocculant is determined using the correlation equation regarding the area. Control can be performed. That is, the flocculant addition management according to the current geological properties can be performed, and the flocculant is added to the turbid water without excess or deficiency.

  Examples of the flocculant include aluminum flocculants and polymer flocculants. Among them, the aluminum-based flocculant is a flocculant which is said to have high solubility and immediate effect, such as sulfuric acid band and PAC (polyaluminum chloride). When excessively dissolved in turbid water, the pH decreases or white turbidity due to aluminum hydroxide. May occur, which may increase the turbidity. In addition, when the excess or deficiency of the aluminum-based flocculant occurs, the generation of flocs by the polymer-based flocculant also has an adverse effect, and the overall efficiency of turbidity reduction due to the addition of the flocculant becomes poor. However, as described above, according to the present invention, an appropriate amount of the flocculant is added according to the turbidity. The effect of improving the speed is also achieved.

  According to the present invention, the flocculant can be allowed to act at low cost and without waste according to turbidity.

It is a figure which shows the example of application of the flocculant addition management method in this embodiment. It is a flowchart which shows the process sequence example of the coagulant | flocculant addition management method in this embodiment. It is a figure which shows the example of an excavation cycle in this embodiment. It is a figure which shows the example of a relationship between the suspended matter density | concentration and turbidity in this embodiment. It is a figure which shows the example of the required addition amount of the flocculant in this embodiment. It is a figure which shows the example of a process result in this embodiment.

--- Application example ---
Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram illustrating an application example of the flocculant addition management method in the present embodiment. In the example shown in the figure, the raw water 1 generated in the construction or the like is once guided to the sand settling tank 2 and then the turbid water 3 as the supernatant water is introduced into the thickener 5 via the transfer line 4. The sand settling tank 2 plays a role of sinking particles having a relatively large particle size that settles in a few seconds. A suitable pressure pump 6 is installed in the upper part of the sand settling tank 2, and supernatant water, that is, muddy water 3 in the sand settling tank 2 flows into the transport line 4 via the pressure feed pump 6. The particles contained in the inflowing turbid water 3 are mainly so-called suspended suspensions that require the addition of a flocculant to settle. Suspended suspensions are charged and have electrostatic repulsive forces acting on each other. They do not settle themselves over time, and their particle size is so small that they are difficult to remove by ordinary physical treatment. . Therefore, if a flocculant that functions to neutralize the charge is added to the turbid water, the suspended suspensions lose their electrostatic repulsive force and aggregate with each other.

  Accordingly, when an appropriate amount of flocculant is added in the conveying line 4 in accordance with the turbidity of the turbid water 3, the turbid water 3 flowing into the thickener 5 is likely to form an appropriate floc to reduce the turbidity. Therefore, a flocculant addition pump 8 is connected to the transport line 4 via a line reactor 7. The flocculant addition pump 8 sucks the flocculant 10 from the flocculant tank 9 and supplies an appropriate amount of flocculant to the line reactor 7 via the flow rate adjustment valve 11. The line reactor 7 is a device that crosses the flow of the muddy water 3 sent from the sand settling tank 2 and the flow of the flocculant 10 from the flocculant addition pump 8 and mixes them together.

  The flow rate adjusting valve 11 is connected to a computer 20 as a control device for controlling the valve opening / closing mechanism. For example, the computer 20 sends a signal (data indicating turbidity) sent from a turbidimeter 25 (for example, measurable turbidity range: 10 to 19990 mg / L) installed in the sand settling tank 2 to a predetermined interface. The valve opening / closing mechanism calculates a required amount of the flocculant required according to the magnitude of the turbidity value indicated by the signal and sets the opening corresponding to the required amount (flow rate). Notify The computer 20 substitutes the value of the turbidity into the correlation equation previously stored in the storage means when calculating the necessary amount. The correlation equation is an equation showing the relationship between the turbidity of the turbid water 3 to be treated and the amount of the flocculant 10 that lowers the turbidity to a predetermined standard. The correlation equation estimation procedure will be described later. The correlation equation is more suitable if it is created for each region having different geological properties based on the geological map relating to the construction target location.

  Moreover, as the flocculant 10 in this embodiment, PAC (polyaluminum chloride) and a polymeric flocculant are mentioned, for example. PAC neutralizes the charge of suspended suspension contained in turbid water 3 and aggregates each other, and then forms a flock by acting a polymer flocculant on the suspended suspension where aggregation has progressed. Therefore, the turbidity can be reduced. The application example of the flocculant 10 is merely an example, and the flocculant to be employed varies depending on the properties of the turbid water and the required flocculant effect (of course, only one kind of flocculant may be used). Further, for adjusting the pH of the muddy water 3, for example, carbon dioxide may be supplied to the transport line 4. In the example shown in FIG. 1, a carbon dioxide supply mechanism 12 and a pH measurement device 13 are arranged in preparation for the case where the pH of the muddy water 3 is high. Therefore, the supply mechanism 12 acquires the pH measurement value of the muddy water 3 from the pH measurement device 13, and supplies a predetermined amount of carbon dioxide gas to the transport line 4 when the pH measurement value is equal to or greater than a predetermined reference. .

  Further, the thickener 5 includes a dehydrating means such as a filter press, and the floc contained in the muddy water 3 is filtered with a filter cloth of the filter press to generate a cake, which is discharged to the outside. In addition, the water separated from the muddy water 3 by the thickener 5 is sent to the treated water tank 40 where it is discharged into rivers etc. after the water quality meets the predetermined management standards (water pollution prevention law, local government regulations, etc.). .

--- Procedure control procedure ---
Then, the example of a procedure of flocculant addition management is demonstrated. FIG. 2 is a flowchart illustrating an example of a processing procedure of the flocculant addition management method in the present embodiment, and FIG. 3 is a diagram illustrating an example of an excavation cycle in the present embodiment. Here, a mountain tunnel excavation site is taken as an example of muddy water generation site. As shown in FIG. 3, the excavation cycle of a mountain tunnel consists of excavation of a face using an excavator or the like, slippage to the outside of the mine, primary spraying of concrete onto the wall such as the face, installation of a steel support, The next spraying operation and the rock bolt driving operation are repeated. In addition, after the concrete secondary spraying work, the batcher plant and the truck mixer truck are cleaned outside the mine. Among these, in particular, muddy water generated during excavation and slipping work, drilling water accompanying rock bolting work, cleaning water for various equipment generated after concrete spraying work and machine maintenance, cleaning water for batcher plants and truck mixer trucks, etc. Tends to be raw water of muddy water 3. Naturally, turbid water having a different concentration is generated for each operation in the above cycle.

  Therefore, for example, in a tunnel ground that is a construction target location, samples such as rocks and earth and sand to be handled at the time of the predetermined work in the cycle are collected, and a plurality of muddy waters having different turbidity are created from the samples (s100). When creating muddy water, for example, a rock mass collected from a natural ground is put into a crushing device to reduce the particle size to a predetermined diameter to produce a powder, and a predetermined amount of water is added to a certain amount of powder. To turbid water with the specified turbidity. Of course, such a muddy water generation method is merely an example, and an appropriate method may be employed depending on the situation in the field and the equipment that can be prepared. In addition, it is more suitable if the collection of the said sample is performed about each area | region of a different geological property based on the geological map regarding the natural ground of the construction object location. In this case, a plurality of muddy waters having different turbidity from each other are created for each region.

  For turbid water of different turbidity generated in the above step s100, a flocculant is added to reduce the turbidity to a predetermined standard (example: 2 ppm), and the required amount is measured (s101). A correlation equation with the necessary amount of the agent is estimated for each region (s102). In this case, for example, a certain amount of the flocculant 10 is added to turbid water having a certain turbidity, and the turbidity change at that time is measured and observed. Then, the total amount of the flocculant 10 added when the predetermined standard turbidity is reached is specified as “necessary amount”.

  Note that the measured value obtained by the turbidimeter 25, that is, turbidity has a correlation with the suspended substance concentration (so-called SS concentration), and the correlation equation is obtained as shown in FIG. 4 as an example. It was. In the example of the figure, the correlation formula is suspended substance concentration = 0.705 × turbidity + 46.634. Therefore, the suspended substance concentration can be calculated by substituting the turbidity value, which is the measurement value of the turbidimeter 25, into this equation. If the correlation equation is set in advance in the arithmetic device, arithmetic program, etc. of the turbidimeter 25, the measured value output as the turbidimeter 25 becomes the suspended substance concentration value.

  FIG. 5 is a diagram showing an example of the required addition amount of the flocculant in the present embodiment. As a result of performing the necessary amount of specific work related to the flocculant 10 as described above, as shown in the graph of FIG. 5, the suspended substance concentration (0 to 25000) and the flocculence are obtained for each flocculant of PAC and polymer flocculant. The relationship of the required amount (ml / min) of the agent 10 was obtained. As can be seen from these graphs, the necessary amount of PAC and polymer flocculant increases as the concentration of suspended solids increases. A correlation equation between the turbidity, that is, the suspended solid concentration and the necessary amount may be estimated from the data of the graph. In estimating the correlation formula, for example, an existing program for formulating graph data may be used.

  Subsequently, the control unit that controls the addition mechanism of the flocculant 10 (that is, the flocculant addition pump 8) is used as the correlation equation estimated in step s102 (that is, the automatic control device that controls the opening and closing mechanism of the flow rate adjusting valve 11). (S103). The setting of the correlation formula is a process of storing the data of the correlation formula in a storage unit such as a memory of the computer 20.

  If the above steps are executed, the preliminary preparation for the flocculant addition management is completed. Therefore, it is assumed that tunnel excavation work or the like is performed by actually rotating the excavation cycle described above. The raw water 1 generated by performing such work passes through a predetermined pipe and the like and is introduced into the sand settling tank 2, and the turbid water 3 as the supernatant water flows into the transport line 4. On the other hand, the turbidimeter 25 is installed in the sand settling tank 2 as described above, and the turbidimeter 25 measures the turbidity of the supernatant water of the settling tank 2, that is, the turbid water 3.

  In addition, the computer 20 receives a notification from a terminal such as a construction management office connected via the network to which region (geological property) the currently constructed site corresponds (s104). When notifying about this area, the person in charge of construction collects samples such as earth and sand at the construction site, collates the sample with the geological map, and includes the current construction site in each area indicated by this geological map. It is assumed that the corresponding area is specified and this information is input from the terminal. That is, with such an input operation, the computer 20 is set for a corresponding area including the current construction target portion among the areas constituting the ground or the like.

  On the other hand, the computer 20 acquires the turbidity of the turbid water 3 to be treated from the turbidimeter 25 (s105), and the computer 20 reads out the correlation formula regarding the corresponding region notified in the step s104 from the storage means. The required amount of flocculant is determined by applying the turbidity value obtained in step s105 to the correlation equation for the corresponding region (s106).

  The computer 20 notifies the opening / closing mechanism of the flow rate adjusting valve 11 of a command to set the required amount of the flocculant, that is, the flow rate determined here, so that the required amount of flocculant 10 is added to the muddy water 3. Control is performed (s107).

  In this way, only a necessary amount of the flocculant 10 corresponding to the turbidity of the turbid water 3 is supplied from the flocculant addition pump 8 to the line reactor 7 via the flow rate adjustment valve 11. The suspended suspension contained in the turbid water 3 is neutralized by PAC and aggregates with each other. Further, in the transport line 4, a polymer type flocculant line reactor 7 is installed downstream of the PAC line reactor 7, and as in the case of the PAC, only the necessary amount of flocculant according to the turbidity of the turbid water 3 is provided. 10 is supplied from the flocculant addition pump 8 to the line reactor 7 via the flow rate adjusting valve 11, so that the suspended suspensions that are aggregated with each other are further combined to form an appropriate floc.

  The muddy water 3 in which an appropriate floc is formed in the transport line 4 and the turbidity is reduced flows into the thickener 5. The floc contained in the muddy water 3 is filtered by a filter cloth of a filter press to form a cake and is discharged to the outside. In addition, the water separated from the muddy water 3 by the thickener 5 is sent to the treated water tank 40 where it is discharged into rivers etc. after the water quality meets the predetermined management standards (water pollution prevention law, local government regulations, etc.). It will be.

  As a result of applying the flocculant addition management method of the present embodiment to an actual tunnel excavation site, the inventors of the present application have found that the suspended solid concentration of the turbid water 3, the amount of flocculant 10 added, and the treated water in the treated water tank 40 Each time change of turbidity was obtained as each graph 600-620 shown in FIG. As shown in each graph of FIG. 6, the instruction from the computer 20 to the flocculant addition pump 8, that is, the addition amount of the flocculant (graph 610) is fairly faithful to the turbidity change of the turbid water 3 (graph 600). As a result, it can be seen that the turbidity of the treated water (graph 620) is maintained at a substantially constant low level of about 2 ppm. That is, it can be said that the flocculant 10 is added to the turbid water 3 without excess or deficiency according to the turbidity, and the turbidity of the treated water is also fixed to a low level.

  For reference, a comparison test between the flocculant addition management method of the present embodiment and the conventional method (addition of a certain amount of flocculant regardless of turbidity) was performed. As a result, it was found that the amount of the flocculant used can be effectively reduced as compared with the conventional muddy water treatment. Therefore, the effectiveness of the flocculant addition management method of this embodiment is clear.

  As mentioned above, according to this embodiment, it becomes possible to make a flocculant act according to turbidity at low cost without waste.

  As mentioned above, although embodiment of this invention was described concretely based on the embodiment, it is not limited to this and can be variously changed in the range which does not deviate from the summary.

1 Raw water 2 Settling tank 3 Supernatant water (turbid water flowing into thickener)
4 Conveying Line 5 Thickener 6 Pressure Pump 7 Line Reactor 8 Coagulant Addition Pump 9 Coagulant Tank 10 Coagulant 11 Flow Control Valve 12 Carbon dioxide Supply Mechanism 13 pH Measuring Device 20 Computer 25 Turbidimeter 40 Treatment Water Tank

Claims (2)

A step of collecting a plurality of muddy waters having different turbidity from each sample from each sample by collecting soil samples for each region having different geological properties in the construction target location based on a geological map relating to the construction target location. When,
For each turbid water with different turbidity created for each region, measure the amount of flocculant added to reduce the turbidity to a predetermined standard, and estimate the correlation between the turbidity and the necessary amount of flocculant for each region. A step of setting a correlation equation estimated for each region with respect to a control device that controls the addition mechanism of the flocculant;
Set the said correlation equation for the corresponding region including the current work target portion of the respective areas to the control unit, by the control device, the turbidity of the turbid water to be the processing target that put the current work target portion Obtain from a turbidimeter, apply the turbidity to the correlation equation for the relevant region, determine the required amount of flocculant, and control the addition mechanism so that the required amount of flocculant is added to the turbid water. A process of performing;
The flocculant addition management method characterized by including this. In claim 1,
Collecting a sample of earth and sand at a construction target location, comparing the sample with the geological map, and identifying a corresponding region including a current construction target location among the regions;
Setting the correlation equation for said identified corresponding area to the control unit, by the control device, the turbidity of the turbid water to be the processing target that put the current work target portion obtained from the turbidity meter, the turbidity Determining the required amount of flocculant by applying a degree to the correlation equation for the corresponding region, and controlling the addition mechanism so that the determined required amount of flocculant is added to the turbid water;
The flocculant addition management method characterized by including this.

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