Method for treating asbestos-turbid water

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

Technical Field

[0001] This invention relates to a method for treating asbestos-turbid water.

Background Art

[0002] Conventionally, during the demolition of structures using asbestos, in order not to scatter asbestos, wet treatment has been carried out while peeling asbestos from the structure with ultra-high water pressure and collecting the treated water containing asbestos. In this wet treatment, a large amount of asbestos-turbid water containing asbestos is generated. However, since asbestos needs to be strictly managed, the asbestos-turbid water generated during demolition work etc. must be separated into drainable water and sludge, and the sludge must be discarded as industrial waste. Also, in order to separate drainable water from asbestos-turbid water, for example, the asbestos-turbid water has been filtered using a filtration device equipped with a fine filter with a mesh size of 1 [μm] or less (hereinafter referred to as "fine filter").

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When filtering asbestos-turbid water, the fine filter quickly clogs. Therefore, the filtration devices have to be replaced one after another. As a result, there has been a problem that the filtration work takes both time and cost. Also, if continued to be used with a clogged fine filter, there was a risk that the asbestos-containing water that could not be treated by the fine filter would be directly discharged. An object of the present invention is to provide a method for treating asbestos-turbid water that has good workability and can surely separate the water that can be discharged and the sludge from the asbestos-containing water.

Means for Solving the Problems

[0005] A first invention is a method for treating asbestos-turbid water that separates asbestos-turbid water containing asbestos peeled off from a structure into dischargeable water and sludge, wherein the asbestos-turbid water generated in the process of peeling asbestos from the structure is sent to a reaction tank only for one unit of reaction treatment, left in the reaction tank for a predetermined treatment time to agglomerate and precipitate the solids in the asbestos-turbid water, and then the entire amount of the supernatant liquid in the reaction tank is sent to a relay tank. Each time the transportation of the supernatant liquid to the relay tank is completed, the precipitate in the reaction tank is sent to a sludge collection container, and the supernatant liquid stored in the relay tank is pumped to a dehydrator, and the primary filtrate discharged from this dehydrator is Having a mesh size of 1 [μm] or less continuously sent to a microfilter, and the secondary filtrate filtered by the microfilter is discharged.

[0006] A second invention includes solid-liquid separation means for separating large solids in the asbestos-turbid water, and the asbestos-turbid water after separating the large solids by this solid-liquid separation means is sent to the reaction tank.

[0007] A third invention sends the supernatant liquid generated in the sludge collection container to the reaction tank.

[0008] A fourth invention collects the residue of the dehydrator in a collection container different from the sludge collection container.

Effects of the Invention

[0009] In this invention, since a relay tank is provided between the reaction tank and the dehydrator, even if the processing capacity of the dehydrator is low, the reaction tank can be emptied, and the reaction treatment in the reaction tank can be continuously performed. In addition, since the fine filter is designed to send the primary filtrate squeezed out by the dehydrator, it is less likely to become clogged. Compared with the case of directly sending the asbestos-turbid water recovered from the structure to the fine filter, the number of filter replacements can be significantly reduced. Therefore, according to this invention, asbestos-turbid water can be continuously treated and separated into dischargeable water and sludge. As a result, the workability of the asbestos-turbid water treatment operation is improved, and the cost can also be reduced.

[0010] According to the second invention, since the large solid matter in the asbestos-turbid water is separated and then sent to the reaction tank, for example, the flocculant will not adhere to the large solid matter, and it can function effectively, enabling efficient flocculation sedimentation in the reaction tank.

[0011] According to the third invention, by reprocessing the moisture in the sludge recovery container where the sludge has been once recovered and separating the dischargeable water, the volume of the sludge in the sludge recovery container can be reduced. Therefore, the volume of the waste is reduced, and the disposal cost can be lowered.

[0012] According to the fourth invention, the volume reduction of the sludge to be discarded can be achieved efficiently. If the residue of the dehydrator, which originally has a low water content, is mixed with the sludge recovered from the reaction tank, it will give moisture to the residue. However, if the residue of the dehydrator and the sludge recovered from the reaction tank are recovered separately as in this invention, the volume of the sludge to be finally discarded can be efficiently reduced.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0014] (Embodiment) Embodiments of the present invention will be described below. FIG. 1 is a schematic diagram of a system for treating asbestos-turbid water according to this embodiment. FIG. 2 is a flowchart of the treatment according to the embodiment. This embodiment separates a wall material containing asbestos from a structure and separates the asbestos-turbid water generated at that time into drainable water and sludge containing asbestos.

[0015] The system according to the embodiment shown in FIG. 1 includes an ultra-high-pressure washer 1 that sprays ultra-high-pressure water to wash a surface to be treated containing asbestos, and a dumper truck 2 that collects and stores the asbestos-turbid water W1 containing asbestos-containing substances peeled off by the ultra-high-pressure washing water of the ultra-high-pressure washer 1. Further, in the order of the steps of treating the asbestos-turbid water W1, a solid-liquid separation means 3, a reaction tank 4, a relay tank 5, a dehydrator 6, and a micro-filter (filtration device) 7 are arranged, and a suction device 8 and a sludge collection container 9 are provided.

[0016] The solid-liquid separation means 3 is a basket-shaped member provided in the path for sending the asbestos-turbid water W1 from the dumper truck 2 to the reaction tank 4. By this solid-liquid separation means 3, large solids such as concrete debris in the asbestos-turbid water W1 sent from the dumper truck 2 are separated and recovered.

[0017] The reaction tank 4 is a tank that receives the asbestos-turbid water W1 from which large solids have been removed by the solid-liquid separation means 3 from the asbestos-turbid water W1 sent from the dumper truck 2 for one unit of reaction treatment, leaves it for a predetermined time, and aggregates and precipitates the sludge SL containing asbestos. In addition, a flocculant such as polyaluminum chloride (PAC) is introduced into the reaction tank 4 to aggregate the fine particles in the asbestos-turbid water and make them easier to precipitate. Further, a stirring device 4a is provided in the reaction tank 4. Also, one unit of reaction treatment is an amount corresponding to the capacity of the reaction tank 4.

[0018] 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. The capacity of the relay tank 5 is set to be sufficiently larger than the capacity of the reaction tank 4.

[0019] The dehydrator 6 is connected to the relay tank 5 via liquid pumping means (not shown), and is a device that squeezes out moisture from the supernatant liquid W2 pumped from the relay tank 5. Specifically, the dehydrator 6 has internally formed branched flow paths, each of the branched flow paths is provided with a filtration chamber, and filter media provided in each chamber filter the supernatant liquid W2 flowing into each flow path. At that time, while allowing the supernatant liquid W2 to pass through the filter media provided in each chamber, pressure is applied to the supernatant liquid W2 so that the moisture in the supernatant liquid W2 is sufficiently squeezed out. In this dehydrator 6, the filter media can be removed from the dehydrator 6, residues are recovered from the removed filter media, and the filter media can be washed.

[0020] Also, the microfilter 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 drainable water. The drain outlet of the dehydrator 6 is connected to the microfilter 7 via a pipe, and the primary filtrate W3 discharged from the dehydrator 6 is automatically supplied to the microfilter 7. The suction device 8 is a device for sucking the sludge SL, which is the sediment accumulated at the bottom of the reaction tank 4, and transferring it to the sludge recovery container 9. The sludge recovery container 9 is a drum can or the like, and is a container for recovering the sludge SL containing asbestos to be disposed of as industrial waste.

[0021] (Function, effect, etc.) Using FIG. 2, the treatment procedure of the asbestos-turbid water of this embodiment will be described. First, the operator sucks the generated asbestos-turbid water while cleaning the surface to be treated with the ultra-high pressure washer 1 (step S1), and stores it in the dumper truck (step S2). These steps S1 and S2 can be continuously performed until the capacity of the dumper truck 2 is full with the asbestos-turbid water W1. However, if the asbestos-turbid water W1 is stored in the dumper truck 2 in an amount more than one unit of the reaction treatment in the reaction tank 4, it may be temporarily interrupted.

[0022] When asbestos-turbid water W1 is stored in the dumper truck 2, in step S3, the operator activates the liquid feeding means to send the asbestos-turbid water W1 to the reaction tank 4 by an amount corresponding to one unit of the reaction process in the reaction tank 4, here about 4 [m 3 only to the reaction tank 4. The asbestos-turbid water W1 from which large solids have been removed by the solid-liquid separation means 3 is sent to the reaction tank 4.

[0023] In step S4, a flocculant such as polyaluminum chloride (PAC) is added to the reaction tank 4, stirred and dissolved by the stirring device 4a, and then left standing for a predetermined time to cause the fine particles to flocculate and precipitate. The required treatment time in the reaction tank 4 varies depending on the solid concentration and the volume, but for asbestos-turbid water W1 of a standard concentration of about 4 [m 3 , it is left standing for 5 to 10 minutes. When the predetermined treatment time has elapsed, in step S5, the operator operates the water feeding means to send the supernatant liquid W2 in the reaction tank 4 to the relay tank 5. When all of the supernatant liquid W2 has been sent to the relay tank 5, the process proceeds to step S6.

[0024] In step S6, the operator uses the suction device 8 to suck the sludge SL, which is the precipitate accumulated at the bottom in the reaction tank 4, and transfers it to the sludge collection container 9 such as a drum can. When all of the sludge SL has been transferred to the sludge collection container 9 and the reaction tank 4 is empty, the process returns to step S3, and again, the asbestos-turbid water W1 is sent from the dumper truck 2 to the reaction tank 4. The processing from step S3 to step S6 is repeated until the asbestos-turbid water W1 stored in the dumper truck 2 becomes empty.

[0025] On the other hand, in step S5, when the supernatant liquid W2 in the reaction tank 4 is sent to the relay tank 5, the relay tank 5 receives the supernatant liquid W2 (step S7). That is, step S5 and step S7 are almost at the same timing. When the supernatant liquid W2 is stored in the relay tank 5, in step S8, the operator activates the pumping means to pump the supernatant liquid W2 to the dehydrator 6. At this time, the operator can also activate the pumping means to pump the supernatant liquid W2 to the dehydrator 6 when the storage of the supernatant liquid W2 in the relay tank 5 starts. In step S9, the fed supernatant liquid W2 is filtered by the dehydrator 6, and the primary filtrate W3 is sent to the microfilter 7. In step S10, the secondary filtrate W4 that has been filtered by the microfilter 7 and discharged is discharged.

[0026] Steps S7 to S10 are continued until the supernatant liquid W2 stored in the relay tank 5 runs out. Also, if the sludge recovery container 9 that has recovered the sludge SL is left unattended, the supernatant liquid W5 will seep out. Therefore, this supernatant liquid W5 is returned to the reaction tank 4 and coagulated and precipitated together with the asbestos-turbid water W1 in step S4.

[0027] By the above steps S1 to S10, the asbestos-turbid water can be separated into the secondary filtrate W4, which is water that can be discharged, and the sludge SL. Note that since the residue of the dehydrator 6 has had sufficient water squeezed out, it is collected in a recovery container (for example, a gunny sack) different from the sludge recovery container 9 and discarded.

[0028] 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 starting the dehydration treatment with the dehydrator 6, the reaction tank 4 can also start the reaction treatment for the coagulation and precipitation of the newly sent asbestos-turbid water W1. Here, assuming that there is no relay tank 5, the supernatant liquid W2 has to be sent directly from the reaction tank 4 to the dehydrator 6, and during the entire period of the dehydration treatment with the dehydrator 6, the supernatant liquid W2 will remain in the reaction tank 4. Therefore, the dehydration treatment with the dehydrator 6 and the reaction treatment with the reaction tank 4 cannot be carried out simultaneously. On the other hand, by providing the relay tank 5 between the reaction tank 4 and the dehydrator 6, the dehydration treatment with the dehydrator 6 and the reaction treatment with the reaction tank 4 can be carried out simultaneously.

[0029] In particular, when the processing capacity of the dehydrator 6 is low, its processing capacity becomes a bottleneck, and the influence on the reaction process and other processes upstream thereof becomes significant. On the other hand, by providing the relay tank 5 between the reaction tank 4 and the dehydrator 6, even when the processing capacity of the dehydrator 6 is low, the influence on the reaction process and other upstream processes can be suppressed.

[0030] Also, since the capacity of the relay tank 5 is larger than that 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, a new supernatant liquid W2 can be sent from the reaction tank 4 to the relay tank 5. And each time the transportation of the supernatant liquid W2 is completed, the sludge SL in the reaction tank 4 can be recovered. Therefore, regardless of the progress of the processing of the dehydrator 6, once the reaction process is completed, the reaction tank 4 can be emptied, and again, the asbestos-turbid water W1 can be sent to the reaction tank 4 to continuously perform the reaction process of coagulation and sedimentation.

[0031] As described above, in this embodiment, the processes of steps S3 to S6 in FIG. 2 and the processes of steps S7 to S10 are executed in parallel, and the overall processing efficiency can be improved. In addition, since the primary filtrate W3 squeezed out by the dehydrator 6 is sent to the microfilter 7, the microfilter 7 is less likely to be clogged, and the number of filter replacements can be significantly reduced compared to the case where, for example, the asbestos-turbid water W1 is directly sent to the microfilter 7. Therefore, both the workability of the processing operation and the cost of the filter can be suppressed.

[0032] Note that the above solid-liquid separation means 3 is not essential, but in this embodiment, the large solid matter in the asbestos-turbid water W1 is separated by the solid-liquid separation means 3 and then sent to the reaction tank 4. Therefore, in this embodiment, for example, the coagulant does not adhere to the large solid matter, functions effectively, and the coagulation and sedimentation in the reaction tank 4 are also performed efficiently.

[0033] Also, by returning the moisture (supernatant liquid W5) in the sludge recovery container 9 from which the sludge SL has been recovered to the reaction tank 4 again, the moisture in the sludge recovery container 9 can be reduced, and the ratio of the solid content of the sludge recovered in the sludge recovery container 9 can be increased. Further, the moisture in the sludge recovery container 9 can be reacted again and separated into aggregated and precipitated sludge and dischargeable water.

[0034] Also, 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, it will give moisture to the residue. However, in this embodiment, since the residue of the dehydrator 6 is recovered separately from the sludge recovery container 9, volume reduction by reducing the moisture of the waste can be achieved efficiently.

[0035] The disposal cost of industrial waste depends on the volume of the sludge and the number of sludge recovery containers. However, in this embodiment, since moisture can be sufficiently separated from the asbestos-containing sludge, the disposal cost can be reduced. For example, when sludge containing a large amount of moisture is recovered, the number of drum cans, which are the recovery containers, increases. However, when the moisture in the sludge is reduced as much as possible, the number of necessary drum cans (sludge recovery containers) decreases, and the disposal cost varies greatly. In this embodiment, since it becomes possible to dispose of the drum cans in which sludge with moisture removed as much as possible is recovered, the disposal cost can be significantly reduced compared to the conventional case.

Industrial Applicability

[0036] It is useful at the demolition work site of structures where asbestos has been used.

Explanation of Reference Numerals

[0037] 3 Solid-liquid separation means 4 Reaction tank 5 Relay tank 6 Dehydrator 7 Fine filter 8 Suction device 9 Sludge recovery container W1 Sludge-turbid water W2 Supernatant liquid W3 primary filtrate W4 secondary filtrate W5 supernatant (from the sludge recovery container)

Claims

1. A method for treating asbestos-turbid water containing asbestos separated from a structure, which separates the asbestos-turbid water into drainable water and sludge, comprising: sending the asbestos-turbid water generated during the process of separating asbestos from the structure to a reaction tank by one unit of reaction treatment; leaving it in the reaction tank for a predetermined treatment time to cause solid matter in the asbestos-turbid water to coagulate and settle; sending the entire amount of the supernatant liquid in the reaction tank to a relay tank; each time the transportation of the supernatant liquid to the relay tank is completed, sending the precipitate in the reaction tank to a sludge collection container, and pressuring the supernatant liquid stored in the relay tank to a dehydrator and continuously sending the primary filtrate discharged from this dehydrator to a microfilter having pores of 1 [μm] or less; A method for treating asbestos-turbid water, wherein the secondary filtrate filtered by the microfilter is discharged.

2. equipped with solid-liquid separation means for separating large solid matter in the asbestos-turbid water, and sending the asbestos-turbid water after separating the large solid matter by this solid-liquid separation means to the reaction tank The method for treating asbestos-turbid water according to Claim 1.

3. sending the supernatant liquid generated in the sludge collection container to the reaction tank The method for treating asbestos-turbid water according to Claim 1 or 2.

4. The method for treating asbestos-turbid water according to any one of Claims 1 to 3, wherein the residue of the dehydrator is collected in a collection container different from the sludge collection container.

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