JP2022124510A - Method for treating asbestos-contaminated water - Google Patents

Abstract

To provide a method for surely and efficiently separating asbestos-contaminated water into dischargeable water and sludge.SOLUTION: There is provided a method for treating asbestos-contaminated water, for separating asbestos-contaminated water W1 containing asbestos stripped from a structure by ultra-high pressure washing water into water W4 that can be discharged and sludge SL, the method including: sending one unit portion of reaction treatment of asbestos-contaminated water to a reaction tank 4, the asbestos-contaminated water being generated in a process of stripping asbestos from the structure; sending an entire amount of supernatant liquid W2 of the reaction tank 4 to a relay tank 5 after coagulating and settling a solid matter in the asbestos-contaminated water by leaving it in the reaction tank 4 for a predetermined treatment time; sending a sediment in the reaction tank 4 to a sludge collection container 9 every time a transportation of the supernatant liquid W2 to the relay tank 5 is completed; pumping the supernatant liquid W2 stored in the relay tank 5 to a dehydrator 6, and continuously sending primary filtrate W3 discharged from the dehydrator 6 to a fine filter 7; and discharging secondary filtrate W4 filtered by the fine filter 7.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for treating asbestos-contaminated water.

In order to prevent the scattering of asbestos when dismantling structures that use asbestos, the asbestos is stripped off from the structure using ultra-high water pressure, and the wet process is used to recover the treated water containing asbestos. It is done. This wet treatment generates a large amount of asbestos-contaminated water containing asbestos.
However, since asbestos must be strictly managed, asbestos-contaminated water generated during demolition work must be separated into water that can be discharged and sludge, and the sludge must be discarded as industrial waste.
Further, in order to separate the water that can be discharged from the asbestos-contaminated water, the asbestos-contaminated water is filtered using a filtering device equipped with a fine filter of 1 [μm] or less (hereinafter referred to as a “fine filter”).

JP 2019-209324 A Japanese Patent No. 6542940

Filtering asbestos-contaminated water quickly clogs the fine filter. Therefore, the filtering device must be replaced one after another. As a result, there is a problem that the filtration work takes time and costs.
Further, if the clogged fine filter is continued to be used, there is a possibility that the asbestos-containing water that cannot be treated by the fine filter and overflows may be discharged as it is.
SUMMARY OF THE INVENTION An object of the present invention is to provide a method for treating asbestos-contaminated water with good workability and capable of reliably separating the asbestos-containing water into dischargeable water and sludge.

A first invention is a method for treating asbestos-contaminated water that separates asbestos-contaminated water that has been separated from a structure by ultrahigh-pressure washing water into water that can be discharged and sludge, the method comprising: The asbestos-contaminated water generated in the process of removing asbestos was sent to a reaction tank for one unit of reaction treatment, and left in the reaction tank for a predetermined treatment time to coagulate and sediment solids in the asbestos-contaminated water. After that, the entire amount of the supernatant liquid in the reaction tank is sent to the relay tank, and every time the transportation of the supernatant liquid to the relay tank is completed, the sediment in the reaction tank is sent to the sludge collection container and stored in the relay tank. The filtered supernatant is pumped to a dehydrator, the primary filtrate discharged from the dehydrator is continuously sent to a fine filter, and the secondary filtrate filtered by the fine filter is discharged.

The second invention is provided with solid-liquid separation means for separating the large solids in the asbestos-contaminated water, and the asbestos-contaminated water after separating the large solids by the solid-liquid separation means is sent to the reaction tank.

A third aspect of the invention sends the supernatant generated in the sludge recovery vessel to the reaction tank.

A fourth aspect of the invention collects the residue of the dehydrator in a collection container different from the sludge collection container.

In this invention, since the relay tank is provided between the reaction tank and the dehydrator, even if the treatment capacity of the dehydrator is low, the reaction tank can be emptied, and the reaction treatment in the reaction tank can be continued continuously. can do.
In addition, since the primary filtrate squeezed out by the dehydrator is sent to the fine filter, clogging of the fine filter is less likely to occur. Therefore, the frequency of filter replacement can be greatly reduced.
Therefore, according to the present invention, asbestos-contaminated water can be continuously treated and separated into water and sludge that can be discharged. Therefore, the workability of the treatment of asbestos-contaminated water is improved, and the cost can be reduced.

According to the second invention, since the large solids in the asbestos-contaminated water are separated before being sent to the reaction tank, the flocculant, for example, does not adhere to the large solids and functions effectively. , the coagulation sedimentation in the reaction tank can be efficiently performed.

According to the third invention, the water in the sludge recovery container once collected is treated again to separate the water that can be discharged, thereby reducing the volume of the sludge in the sludge recovery container. Therefore, the volume of waste is reduced, and the disposal cost can be lowered.

According to the fourth invention, it is possible to efficiently reduce the volume of sludge to be discarded. Although the residue of the dehydrator originally has a low water content, if it is mixed with the sludge recovered from the reaction tank, the residue will be moistened. However, if the residue of the dehydrator and the sludge recovered from the reaction tank are recovered separately as in the present invention, the volume of the sludge to be finally discarded can be efficiently reduced.

FIG. 1 is a schematic diagram of a system for implementing embodiments of the invention. It is a flow chart of processing of an embodiment.

(embodiment)
Embodiments of the present invention are described below. FIG. 1 is a schematic diagram of the system for treating asbestos-contaminated water of this embodiment. FIG. 2 is a flowchart of the processing of the embodiment.
In this embodiment, asbestos-containing wall materials are separated from a structure, and asbestos-contaminated water generated at that time is separated into water that can be discharged and sludge containing asbestos.

The system of the embodiment shown in FIG. A dumper truck 2 for collecting and storing asbestos-contaminated water W1 containing substances is provided. In addition, a solid-liquid separation means 3, a reaction tank 4, a relay tank 5, a dehydrator 6, and a fine filter (filtration device) 7 are arranged in the order of processes for treating the asbestos-contaminated water W1, and a suction device 8 and sludge recovery are arranged. A container 9 is provided.

The solid-liquid separation means 3 is a basket-like member provided in a route for sending the asbestos-contaminated water W1 from the dumper truck 2 to the reaction tank 4. As shown in FIG. The solid-liquid separating means 3 separates and recovers large solids such as concrete scum in the asbestos-contaminated water W1 sent from the dumper truck 2. As shown in FIG.

The reaction tank 4 receives asbestos-contaminated water W1 from which large solids have been removed by the solid-liquid separation means 3 from the asbestos-contaminated water W1 sent from the dumper vehicle 2, for one unit of the reaction treatment, and left for a predetermined time. is a tank for coagulating and sedimenting sludge SL containing A flocculant such as polyaluminum chloride (PAC) is added to the reaction tank 4 to flocculate fine particles in the asbestos-contaminated water to facilitate precipitation. In addition, the reaction tank 4 is provided with a stirring device 4a. One unit of reaction processing is an amount corresponding to the capacity of the reaction tank 4 .

The relay tank 5 is a tank for storing the supernatant liquid W2 sent from the reaction tank 4 after the treatment in the reaction tank 4 is finished. The capacity of the relay tank 5 is set sufficiently larger than the capacity of the reaction tank 4 .

The dehydrator 6 is a device that is connected to the relay tank 5 via a liquid pumping means (not shown) and squeezes moisture from the supernatant liquid W2 pumped from the relay tank 5 . Specifically, the dehydrator 6 is formed with branched flow paths inside, and each of the branched flow paths is provided with a filtration chamber. W2 is filtered. At this time, pressure is applied to the supernatant liquid W2 while passing it through the filter media provided in each chamber, so that the water content of the supernatant liquid W2 is sufficiently squeezed out. In this dehydrator 6, a filter medium can be removed from the dehydrator 6, and residue can be recovered from the removed filter medium and the filter medium can be washed.

Further, the fine filter 7 is a filter capable of capturing particles of several [μm] or less, and is a device that filters the primary filtrate W3 squeezed out by the dehydrator 6 and discharges the secondary filtrate W4 as water that can be discharged. is. A drain port of the dehydrator 6 is connected to the fine filter 7 via a pipe so that the primary filtrate W3 discharged from the dehydrator 6 is automatically supplied to the fine filter 7 .
The suction device 8 is a device for sucking the sludge SL, which is a sediment accumulated on the bottom of the reaction tank 4, and transferring it to the sludge recovery container 9.
The sludge collection container 9 is a drum or the like, and is a container for collecting sludge SL containing asbestos to be disposed of as industrial waste.

(action, effect, etc.)
A procedure for treating asbestos-turbid water in this embodiment will be described with reference to FIG.
First, an operator sucks up the generated asbestos-contaminated water while washing the surface to be treated with the ultra-high pressure washer 1 (step S1), and stores it in a dumper vehicle (step S2). These steps S1 and S2 can be performed continuously until the capacity of the damper truck 2 is filled with the asbestos-contaminated water W1. However, when asbestos-contaminated water W1 is stored in the dumper truck 2 for one unit or more of the reaction process in the reaction tank 4, the process may be temporarily interrupted.

After the asbestos-contaminated water W1 is stored in the dumper truck 2, in step S3, the operator operates the liquid feeding means to pour the asbestos-contaminated water W1 for one unit of reaction treatment in the reaction tank 4, here the reaction tank 4. Approximately 4 [m ³ ] is sent to the reaction tank 4 according to the capacity of . The asbestos-contaminated water W1 from which large solids have been removed by the solid-liquid separation means 3 is sent to the reaction tank 4 .

In step S4, a coagulant such as polyaluminum chloride (PAC) is added to the reaction tank 4, dissolved by stirring with the stirring device 4a, and allowed to stand for a predetermined time to coagulate and precipitate the fine particles. The treatment time required in the reaction tank 4 varies depending on the concentration of solid matter and the volume, but if the standard concentration of asbestos-contaminated water W1 is about 4 [m ³ ], leave it for 5 to 10 minutes. .
After a predetermined treatment time has elapsed, the worker operates the water supply means to send the supernatant liquid W2 of the reaction tank 4 to the relay tank 5 in step S5. When the entire amount of the supernatant liquid W2 has been sent to the relay tank 5, the process proceeds to step S6.

In step S6, the worker sucks the sludge SL, which is a sediment, accumulated at the bottom of the reaction tank 4 using the suction device 8, and transfers it to a sludge recovery container 9 such as a drum can. When all the sludge SL is transferred to the sludge recovery container 9 and the reaction tank 4 becomes empty, the process returns to step S3, and the asbestos-contaminated water W1 is sent from the dumper truck 2 to the reaction tank 4 again.
The processing from step S3 to step S6 is repeated until the asbestos-contaminated water W1 stored in the dumper truck 2 is empty.

On the other hand, when the supernatant liquid W2 of the reaction tank 4 is sent to the relay tank 5 in step S5, the relay tank 5 receives the supernatant liquid W2 (step S7). That is, step S5 and step S7 are performed at substantially the same timing.
After the supernatant liquid W2 is stored in the relay tank 5, the operator operates the pumping means to pump the supernatant liquid W2 to the dehydrator 6 in step S8. At this time, the worker can operate the pumping means to pump the supernatant liquid W2 to the dehydrator 6 when the supernatant liquid W2 starts to be stored in the relay tank 5 .
In step S 9 , the sent supernatant liquid W 2 is filtered by the dehydrator 6 and the primary filtrate W 3 is sent to the fine filter 7 .
In step S10, the secondary filtrate W4 filtered by the fine filter 7 and discharged is discharged.

Steps S7 to S10 are continued until the supernatant liquid W2 stored in the relay tank 5 is exhausted.
In addition, if the sludge collection container 9 in which the sludge SL is collected is left to stand, the supernatant liquid W5 will seep out. .

Through the steps S1 to S10 described above, the asbestos-contaminated water can be separated into the secondary filtrate W4, which is water that can be discharged, and the sludge SL.
Since the residue of the dehydrator 6 has been sufficiently squeezed out of water, it is collected in a collection container (for example, jute bag) different from the sludge collection container 9 and discarded.

In this embodiment, since the relay tank 5 is provided between the reaction tank 4 and the dehydrator 6, the supernatant liquid W2 is sent from the reaction tank 4 to the relay tank 5, and while the dehydration treatment is started in the dehydrator 6, the reaction Also in the tank 4, the reaction process for coagulation and sedimentation of the newly sent asbestos-contaminated water W1 can be started. Here, assuming that there is no relay tank 5, the supernatant liquid W2 must be directly sent from the reaction tank 4 to the dehydrator 6, and the Liquid W2 remains. Therefore, the dehydration treatment in the dehydrator 6 and the reaction treatment in the reaction tank 4 cannot be performed simultaneously. On the other hand, by providing the relay tank 5 between the reaction tank 4 and the dehydrator 6, the dehydration treatment in the dehydrator 6 and the reaction treatment in the reaction tank 4 can be performed simultaneously.

In particular, when the processing capacity of the dehydrator 6 is low, the processing capacity becomes a bottleneck, and the influence on the reaction process, which is the process on the upstream side, becomes significant. On the other hand, since the relay tank 5 is provided between the reaction tank 4 and the dehydrator 6, even if the processing capacity of the dehydrator 6 is low, the influence thereof reaches the reaction process on the upstream side. can be suppressed.

Further, since the capacity of the relay tank 5 is larger than the capacity of the reaction tank 4, even if the processing capacity of the dehydrator 6 is low and the supernatant liquid W2 remains in the relay tank 5, new supernatant liquid from the reaction tank 4 can be obtained. W2 can be sent to the relay tank 5 . Then, the sludge SL in the reaction tank 4 can be collected every time the transportation of the supernatant liquid W2 is finished. Therefore, regardless of the progress of the treatment in the dehydrator 6, when the reaction treatment is completed, the reaction tank 4 is emptied, and the asbestos-contaminated water W1 is again sent to the reaction tank 4 to continue the reaction treatment for coagulation and sedimentation. can be done systematically.

As described above, in this embodiment, the processing of steps S3 to S6 in FIG. 2 and the processing of steps S7 to S10 are executed in parallel, thereby improving the overall processing efficiency.
Further, since the primary filtrate W3 squeezed out by the dehydrator 6 is sent to the fine filter 7, the fine filter 7 is less likely to clog. Compared to the case, the number of times the filter needs to be replaced can be drastically reduced.
Therefore, it is possible to suppress the cost of the filter as well as the workability of the treatment work.

Although the solid-liquid separation means 3 is not essential, in this embodiment, the solid-liquid separation means 3 separates the large solids in the asbestos-contaminated water W1 and then sends them to the reaction tank 4 . Therefore, in this embodiment, for example, the flocculant does not adhere to large-sized solids, functions effectively, and flocculation and sedimentation in the reaction tank 4 is also efficiently performed.

In addition, by returning the water (supernatant liquid W5) in the sludge collection container 9 in which the sludge SL has been collected to the reaction tank 4 again, the water content in the sludge collection container 9 is reduced, and the amount of sludge collected in the sludge collection container 9 is reduced. High percentage of solids can be achieved. Furthermore, the water in the sludge recovery container 9 can be reacted again to separate the sludge that has aggregated and precipitated and the water that can be discharged.

Moreover, if the residue of the dehydrator 6, which originally has a low water content, is mixed with the sludge SL recovered from the reaction tank 4, the residue will be moistened. However, in this embodiment, since the residue of the dehydrator 6 is collected separately from the sludge collection container 9, the water content of the waste can be efficiently reduced.

The disposal cost of industrial waste depends on the volume of sludge and the number of sludge collection containers, but in this embodiment, water can be sufficiently separated from the asbestos-containing sludge, so the disposal cost can be reduced. can. For example, when sludge containing a lot of water is collected, the number of drums used as collection containers increases. is reduced, and disposal costs are significantly different. In this embodiment, it is possible to dispose of the drums from which the sludge from which water has been removed as much as possible has been collected, so that the disposal cost can be greatly reduced compared to the conventional method.

It is useful at demolition work sites of structures using asbestos.

3 Solid-liquid separation means 4 Reaction tank 5 Relay tank 6 Dehydrator 7 Fine filter 8 Suction device 9 Sludge collection container W1 Sludge-contaminated water W2 Supernatant liquid W3 Primary filtrate W4 Secondary filtrate W5 Supernatant liquid (of sludge collection container)

A first invention is a method for treating asbestos-contaminated water containing asbestos that has been stripped from a structure and is separated into water that can be discharged and sludge, wherein the asbestos is stripped from the structure. The asbestos-contaminated water generated in the process is sent to a reaction tank for one unit of reaction treatment, and left in the reaction tank for a predetermined treatment time to coagulate and sediment solids in the asbestos-contaminated water. The entire amount of the supernatant liquid in the tank is sent to the relay tank, and every time the transportation of the supernatant liquid to the relay tank is completed, the sediment in the reaction tank is sent to the sludge collection container, and the supernatant liquid stored in the relay tank is transferred. is pumped to a dehydrator, the primary filtrate discharged from the dehydrator is continuously sent to a fine filter, and the secondary filtrate filtered by the fine filter is discharged.

Claims (4)

A method for treating asbestos-contaminated water, which separates asbestos-contaminated water containing asbestos separated from structures by ultrahigh-pressure washing water into water that can be discharged and sludge,
Sending the asbestos-turbid water generated in the process of stripping asbestos from the structure to a reaction tank for one unit of reaction treatment,
After allowing the solid matter in the asbestos-contaminated water to coagulate and settle for a predetermined treatment time in the reaction tank,
Sending the entire amount of the supernatant liquid of the reaction tank to the relay tank,
Every time transportation of the supernatant liquid to the relay tank is completed, the sediment in the reaction tank is sent to the sludge collection container,
The supernatant liquid stored in the relay tank is pumped to a dehydrator, and the primary filtrate discharged from the dehydrator is continuously sent to a fine filter,
A method for treating asbestos-contaminated water by discharging the secondary filtrate filtered through the fine filter. Equipped with solid-liquid separation means for separating large solids in the asbestos-turbid water,
2. The method for treating asbestos-contaminated water according to claim 1, wherein the asbestos-contaminated water after separating the large solids by the solid-liquid separation means is sent to the reaction tank. 3. The method for treating asbestos-contaminated water according to claim 1 or 2, wherein the supernatant liquid generated in said sludge recovery vessel is sent to said reaction tank. The method for treating asbestos-contaminated water according to any one of claims 1 to 3, wherein the residue from the dehydrator is recovered in a recovery container different from the sludge recovery container.

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