JP3924738B2 - How to recycle dredged clay - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recycling process for construction sludge generated by dredging.
[0002]
[Prior art]
Conventionally, as a method for recycling construction sludge, a method is known in which a water-absorbing agent and a solidifying agent are added to and mixed with a sludge dewatered cake and subjected to solidification by a mixer to form a granular material, thereby producing granular soil.
[0003]
However, when the sludge sludge is recycled by the above-described method, the conventional sludge sludge method has a high water content (moisture content of 900 to 1000%), and it is not possible to directly solidify this. Since it is possible, solidification processing was performed after dewatering the dredged mud water.
[0004]
There is also known a method of dredging with a high-concentration dredger and making dredged water less water (water content ratio: 300 to 500%) than the above method, and directly solidifying it.
[0005]
[Problems to be solved by the invention]
However, in the conventional technology as described above, when dredging by the conventional sludge dripping method, it is necessary to concentrate dredged water so that it can be processed by the dehydrating device before dehydrating by the dehydrating device. There was a problem that an apparatus was required and efficiency was low.
[0006]
In addition, in the case of muddy water from a high concentration dredger, the water content in dredged mud is small (moisture content ratio: 300 to 500%), but when this is directly solidified, a large amount of chemicals such as water-absorbing agents and solidifying agents are used. The cost of chemicals increases because it is necessary, and in addition, there is a problem that only solidified soil with unstable quality can be made. Furthermore, since water is not separated, it cannot be dissolved and is now a problem. It could not be an effective measure against the sludge treatment plant shortage.
[0007]
The present invention has been made in view of the above-described state of the art, and an object of the present invention is to provide a low-cost recyclable clay recycling method with a simple configuration.
[0008]
[Means for Solving the Problems]
The feature of the present invention for solving the conventional problems as described above and achieving the intended purpose is to screen the dredged water dredged by the high concentration dredger and remove the gravel and impurities, and then the flocculant reaction feeding the vessel, then added to and mixed with coagulant in coagulant reaction vessel to produce flocs, feed the screw press on after turning off the water dredging mud which the flock is generated by sending the draining conveyor, the A dehydrating cake is obtained by dewatering in a screw press, and a solidifying agent is added to and mixed with the dewatered cake to form a granular soil.
[0009]
In addition, surplus water at the time of dehydration is sent to a surplus water treatment device, the supernatant separated from the sludge in the sedimentation tank of the surplus water treatment device is discharged, and the sediment containing sludge is sent to the flocculant reaction tank. preferable.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the clay recycling method according to the present invention will be described.
[0011]
FIG. 1 is a schematic diagram showing an outline of a clay recycling system according to the present invention.
[0012]
This system includes a dredging work section A that performs dredging work, a dewatering work section B that performs dewatering work, and a solidification processing section C that generates granular soil. The muddy water is dehydrated in the dewatering operation unit B to form a dehydrated cake, and the dehydrated cake is converted into a granular soil that is a recycled product in the solidification processing unit C.
[0013]
The dredging work unit A includes a high-concentration dredger 1 and a mud feeding device 2 that sends dredged water dredged by the high-concentration dredger 1 to the dewatering work unit B.
[0014]
The high-concentration dredger 1 is provided with a mud collector 4 at the tip of the dredger 1 and a mud pump (not shown) is installed in the mud collector 4, and the collected soft mud is taken in by the mud collector 4. The suction of excess water is prevented and high concentration dredging is enabled by controlling the mud collector moving speed and the suction amount based on the amount of mud sucked on the ship and flowing into the mud collector 4.
[0015]
The mud feeding device 2 equalizes the concentration of dredged water, a vibrating screen 5 that removes gravels and impurities from dredged mud, a mud storage tank 6 that temporarily stores dredged mud from which the impurities, etc. have been removed. And a supply pump 8 for feeding dredged mud water to the dehydrating work part B.
[0016]
The dewatering work section B processes the coagulant reaction tank 9 for adding flocculant to the dredged mud water fed from the dredging work section A to generate flocs, the screw press 10 as a dehydrator, and the remaining water during dehydration. The spillage treatment apparatus 11, the flocculating agent reaction tank 9, and the flocculating agent supply apparatus 12 that supplies the flocculating agent b to the sewage treatment apparatus 11, and the flocculating agent reaction tank 9 and the sewage treatment apparatus 11 are supplied with the flocculant a. And a flocculant supply device 13.
[0017]
In general, a polymer flocculant is used as the flocculant a, and an inorganic salt flocculant is used as the flocculant b.
[0018]
The flocculant reaction tank 9 includes a stirring tank 14 for adding and mixing the flocculant a to the fed mud water, and a mixing tank 15 for adding and mixing the flocculant b to the mud water. 15, the muddy water having a uniform concentration in the stirring tank 14 is sequentially fed into the mixing tank 15.
[0019]
In the mixing tank 15, the muddy water to which the flocculant a and the flocculant b are added is mixed by stirring with a screw-like stirrer 16 to generate floc.
[0020]
The dredged mud water in which the flocs are generated is sent to the draining conveyor unit 37, where the moisture is cut in advance and then sent into the screw press 10.
[0021]
The screw press 10 includes a screen cylindrical portion 17 having permeability and a screw shaft 18 in which blades are spirally attached. The screw shaft 18 is rotated by supporting both ends inside the screen cylindrical portion 17 by bearings. Held possible. Further, the screw shaft 18 can be directly connected to an electric motor or the like so as to be able to rotate, and the shaft diameter gradually increases toward the outlet.
[0022]
With this configuration, the screw press 10 is transferred while applying back pressure to the flock by the rotation of the screw shaft 18, and drains water from the outer peripheral surface of the screen cylindrical portion 17 to perform dehydration. At this time, by gradually increasing the screw shaft diameter toward the outlet side, the pressure increases as it approaches the outlet, and the dewatered cake is granular when discharged from the outlet. The remaining water at the time of dehydration is sent to the remaining water treatment device 11.
[0023]
The residual water treatment device 11 includes a precipitation tank 19 and a precipitation auxiliary device 20.
[0024]
The sedimentation tank 19 is provided with a discharge hole 21 at the top so that the supernatant can be discharged. On the other hand, a return pipe 23 connected to the flocculant reaction tank 9 is connected to the bottom via a pump 22. ing.
[0025]
The precipitation assisting device 20 includes a first stirring tank 24 and a second stirring tank 25, the two stirring tanks 24, 25 are in communication, and the second stirring tank 25 is in communication with the precipitation tank 19. The remaining water sent from the screw press 10 is first sent to the first stirring tank 24 where the flocculant a is added and stirred and sent to the second stirring tank 25. In the second agitation tank 25, the flocculant b is added and sent to the precipitation tank 19. By doing so, mud or the like contained in the excess water is easily aggregated and precipitated by the action of the flocculant.
[0026]
The flocculant supply device 12 includes a flocculant storage tank 26 for storing the flocculant b, and a supply pump 27 for supplying the flocculant b from the flocculant storage tank 26 to the flocculant reaction tank 9 and the residual water treatment device 11. It is composed of
[0027]
The flocculant supply device 13 includes a powder quantitative supply device 28, a fresh water tank 29, a flocculant dissolution tank 30, a flocculant storage tank 31 for storing the dissolved flocculant a, and a flocculant a for flocculant reaction. A supply pump 32 for supplying to the tank 9 and the residual water treatment device 11 is provided.
[0028]
In the flocculant dissolution tank 30, the polymer powder supplied from the powder quantitative supply unit 28 and the fresh water supplied from the fresh water tank 29 are mixed and stirred to dissolve the flocculant a, and the dissolved agglomeration is performed. The agent a is supplied to the flocculant storage tank 31 and stored there. The stored flocculant a is sent to the flocculant reaction tank 9 and the residual water treatment device 11 by the pump 32. In addition, it is also possible to use seawater instead of fresh water for the solution of the flocculant.
[0029]
The solidification processing unit C includes a solidifying agent supply device 33, a mixer 34 that mixes the dehydrated cake to which the solidifying agent is added, and generates the particles, and a conveyor 35 that transfers the generated particles. Yes.
[0030]
Next, the method for recycling clay according to the present invention will be described.
[0031]
First, the muddy water dredged by the high-concentration dredger 1 is sent to the vibrating screen 5 through the mud pipe 36, where the boulders and impurities are removed from the muddy water, and the muddy water from which the impurities are removed. Is temporarily stored in the muddy water storage tank 6.
[0032]
Next, the stored muddy water is sent to the agitation tank 7 where the muddy water is agitated to a uniform concentration, and the muddy water having a uniform concentration is fed into the flocculant reaction tank 9 by the supply pump 8.
[0033]
The muddy water sent to the flocculant reaction tank 9 first enters the stirring tank 14 and is stirred again to a uniform concentration, and after adding the flocculant a from the flocculant supply device 13, it is sent to the mixing tank 15. Here, the flocculant b is added from the flocculant supply device 12 to facilitate the aggregation of the mud. The muddy water is mixed by the stirrer 16 to generate a floc. The generated floc is drained in advance by the conveyor 37 or the like and sent to the screw press 10.
[0034]
The floc sent to the screw press 10 is dehydrated to a water content ratio of about 100% by rotating the screw shaft 13, becomes a granular dehydrated cake, and is sent to the solidification processing unit C. In addition, surplus water containing sludge produced during the dehydration is sent to the surplus water treatment device 11.
[0035]
The surplus water sent to the surplus water treatment device 11 is first sent to the first stirring tank 24, where the flocculant b is added and stirred and mixed. And the coagulant | flocculant a is added and mixed with the residual water mixed with this coagulant | flocculant b in the 2nd stirring tank 25, and it makes it easy to settle the mud contained in the residual water, it is made to settle in the precipitation tank 19, The supernatant portion is continuously discharged to the outside through the discharge hole 21, and the lower sediment is sent to the flocculant reaction tank 9 through the return pipe 23 by the pump 22, and the above steps are repeated.
[0036]
On the other hand, the dehydrated cake sent to the solidification processing section C is conveyed to the mixer 34 by the conveyor 38 or the like, where a solidifying agent such as cement is added and stirred by the mixer 34 and then formed into a granular shape. It is discharged at.
[0037]
【The invention's effect】
As described above, the method for recycling dredged soil according to the present invention is performed by sieving dredged water dredged by a high concentration dredger to remove gravels and contaminants, and then sent to the flocculant reaction tank. The flocculant is added and mixed in to produce floc , and the mud water in which the floc is produced is sent to a draining conveyor section to remove moisture, and then sent to a screw press, dehydrated in the screw press and dehydrated cake As a result, the water content of the dewatered cake can be dewatered to about 100%, the volume can be reduced, and a granular soil with stable quality can be generated, which helps to solve the shortage of construction sludge treatment plant. In addition, since the dredged mud water in which the floc is generated is sent to the draining conveyor section and the moisture is cut off , the concentration process before the dehydration process, which has been conventionally required, can be omitted, and the system is simplified. It becomes.
[0038]
Further, by forming a particulate soil was added to and mixed with solidifying agent to dewatered cake, dehydrated cake is necessary to add water-absorbing agent is granulation rather name cost is reduced to reduce also the amount of the solid agent The Furthermore, since the dehydrated cake has a granular shape, there is an advantage that it can be easily mixed with a solidifying agent when performing the solidification treatment, and the mixer can be simple.
[0039]
Furthermore , by sending surplus water at the time of dehydration to a surplus water treatment device, discharging the supernatant separated from sludge in the sedimentation tank of the surplus water treatment device, and sending the sediment containing sludge to the flocculant reaction tank It is economical because it can process reusable sediment without waste.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a clay recycling system according to the present invention.
[Explanation of symbols]
A Dredging work section B Dehydration working section C Solidification processing section 1 High-concentration dredger 2 Mud feeder 3 Mud collector 4 Fluidizer (rotating cutter)
DESCRIPTION OF SYMBOLS 5 Vibrating sieve 6 Muddy water storage tank 7 Agitation tank 8 Supply pump 9 Coagulant reaction tank 10 Screw press 11 Waste water processing apparatus 12 Coagulant supply apparatus 13 Coagulant supply apparatus 14 Agitation tank 15 Mixing tank 16 Stirrer 17 Screen cylindrical part 18 Screw Shaft 19 Precipitation tank 20 Precipitation auxiliary device 21 Discharge hole 22 Pump 23 Return pipe 24 First stirring tank 25 Second stirring tank 26 Coagulant storage tank 27 Pump 28 Powder fixed quantity supply machine 29 Fresh water tank 30 Coagulant dissolution tank 31 Coagulant Storage tank 32 Supply pump 33 Solidifying agent supply device 34 Mixer 35 Conveyor 36 Mud pipe
37 Draining conveyor 38 Conveyor

Claims (2)

Multiplied by dredging muds dredged by high concentration dredger sieve, Daitsubute, after removal of the contaminants, feed the coagulant reaction vessel, was added and mixed coagulant in coagulant reaction vessel to produce a floc, the floc The produced mud water is sent to a draining conveyor section to cut moisture, and sent to a screw press, dehydrated in the screw press to form a dehydrated cake, and a solidifying agent is added to the dehydrated cake and mixed to form a granular soil. A method for recycling dredged soil characterized by   The surplus water at the time of dehydration is sent to a surplus water treatment device, the supernatant separated from the sludge in the sedimentation tank of the surplus water treatment device is discharged, and the sediment containing sludge is sent to the flocculant reaction tank. Recycling method of dredged soil described.

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