JP3283634B2 - Mud water treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating muddy water for removing water contained in the muddy water, significantly reducing the volume and facilitating transportation. More specifically, muddy water of various properties
The present invention relates to a muddy water treatment method for forming a large and hard floc by a simple operation, separating and removing the same from moisture, thereby significantly reducing the volume of the muddy water and facilitating transportation.

[0002]

2. Description of the Related Art Conventionally, muddy water discharged in a tunnel construction method in a subway tunnel or the like, muddy water discharged in a well drilling work in an oil field or a hot spring, muddy water discharged in a pile driving method such as a reverse pit or an earth drill pit, and a river. The mud discharged from sludge treatment of ponds, sewage treatment, etc. is mixed with groundwater or river water to form a large amount of mud, but if it flows into rivers and sewers as it is, the flow will be gentle. It accumulates in places and causes clogging of river flows and sewers. However, such muddy water is mixed with groundwater and river water to form a large volume of muddy water. Need. Therefore, the mud discharged at the above construction site is used to remove the water in the mud and to dispose of only the solids having a reduced water content to a normal landfill or an industrial waste treatment land, etc. The mud concentration was lowered, the water layer portion was reduced, and only the mud water having a reduced water content was put in a tank and transported to a remote place by a truck or the like.

However, in recent years, the disposal place is also restricted, and there is no particular method for reducing the amount of treatment or a safe treatment method. Therefore, development of such a method is highly desired. Therefore, an acrylic coagulant and polyaluminum chloride (PAC) are blended into the discharged muddy water, and the muddy water is concentrated by allowing it to stand and settle to separate the aqueous layer (see Comparative Examples 3 and 4). ) Alternatively, sodium silicate is blended into the discharged muddy water, and sulfuric acid is added thereto to gel the sodium silicate, and the solid content of the muddy water is adsorbed and separated by the generated gel, and the solid content is separated. The water content of the solid content in the muddy water is reduced by squeezing the gel-like material having adsorbed thereon, and the solid material having the reduced water content is transported to a remote place by a truck or the like for disposal.

On the other hand, in the well drilling work in oil fields and hot springs, a natural gum aqueous solution and a boric acid compound aqueous solution are injected into the soil in order to increase the viscosity of the earth and sand. There is known a method of excavating while improving the overall viscosity.

[0005]

However, a method of concentrating the muddy water by mixing an acrylic flocculant and polyaluminum chloride (PAC) into the muddy water and separating the aqueous layer by standing and sedimenting the aqueous muddy water is compared with the conventional method. As clarified in Examples 3 and 4, muddy water can be dewatered to some extent, but the size of the aggregated particles is small, so that much time is required for the filtration / separation step, which poses a practical problem.

[0006] Further, sodium silicate is blended into the muddy water, and sodium silicate is gelled by adding sulfuric acid to the muddy water. The solid matter of the muddy water is adsorbed and separated by the formed gel, and this solid matter is separated. By squeezing the adsorbed gel, the method of lowering the water content of solids in the mud is difficult to generate large flocs or hard flocs when the concentration of the mud is high, or the seawater component contained in the mud,
Due to the inhibitory action of floc formation by metal salts, humic acid substances and organic substances, the formed flocs become smaller,
Softens. Therefore, when the concentration of the muddy water is high, the concentration must be reduced by adding fresh water, or when there is an inhibitor of the flocculant, a flocculant not affected by the inhibitor must be selected and used. However, the type of mud generated during construction in the same area changes, so that the work of inspecting an appropriate flocculant and adjusting the concentration thereof each time is extremely complicated.

A method of excavating a natural gum aqueous solution and borate compound aqueous solution by injecting the same into the soil to convert the natural gum aqueous solution into a rubbery state and to improve the viscosity of the whole soil is disclosed in US Pat. There is no intention to lower the water content and it is quite different in purpose from muddy water treatment methods. Furthermore, the mud drained from this cutting is
As with ordinary mud, even if it is incorporated into the soil before cutting, the obtained mud has no effect.

[0008]

Means for Solving the Problems [Summary of the Invention] The present inventors have conducted intensive studies in view of the above problems, and as a result, a specific combination of compounding agents aggregates solids in muddy water. The present invention has been completed based on the finding that extremely large particles can be formed, and if the particles are separated by filtration, the water in the muddy water can be separated and removed very easily. is there. That is, the method for treating muddy water of the present invention is a method for separating and removing water by filtration by aggregating solids in muddy water, wherein a natural gum and a boron compound are added to the muddy water. is there.

[I] Detailed description of the invention [I] Treatment of muddy water (1) Muddy water Muddy water to be treated in the muddy water treatment method of the present invention includes a shield method in tunnel construction of a subway or the like.
Mud discharged from well drilling work in oil fields and hot springs, mud discharged by pile driving methods such as reverse pits and earth drill pits, mud discharged from sewage treatment, etc., and sludge treatment of rivers and ponds. Sludge and the like can be mentioned. The use of muddy water generated by the shield method among these muddy waters can remarkably exert its effect. These muddy waters are mixed with groundwater or river water at the time of cutting or the like, and contain a large amount of water and earth and sand. , The specific gravity is generally 1.1 to 1.
5, preferably 1.2 to 1.3, particle size generally 20 to
2,000 μm, preferably 100 to 1,000 μm,
A solid content having a hydrogen ion concentration (pH) of generally 7 to 13, preferably 7 to 11 is generally contained at a ratio of 10 to 50% by weight, preferably 20 to 30% by weight, and has a fluidity of 10 to 10% by weight.
cp to 5,000 cp, preferably 20 to 1,000 c
p. If the mud is allowed to flow into a river or sewer as it is, the mud accumulates in a place where the flow is gentle, causing clogging of the river flow or sewer.

(2) Compounding agents (a) Natural gum Natural gums to be compounded in the muddy water treatment method of the present invention include vegetable rubber and resinous substances contained in gasoline. Is preferred.

Vegetable gum The above-mentioned plant gum is a gum-like substance secreted from plant fruits and bark, and these are formed from a group of polysaccharides. The structure and composition vary depending on the type of plant to be collected, but the pure one is colorless and amorphous and insoluble in ethanol, but when dissolved in water it becomes a highly viscous liquid and exhibits acidity. In many cases, the chemical structure of such plant gums is unknown, but when hydrolyzed, pentose,
It produces hexoses and uronic acids. As the sugar, for example, D-galactose, D-mannose, L-
Arabinose, D-xylose, L-rhamnose and the like, and uronic acids include D-gulonic acid and D-galacturonic acid. Specific examples of such natural gums include guar gum, santa gum, and local bean gum. Of these, guar gum is preferably used.

(B) Boron compound The boron compound to be blended in the muddy water treatment method of the present invention includes a hydride, an oxygen compound, a nitrogen compound, a halogen compound, a sulfide, a carbide, an acetate or an organic boron containing boron. Specific examples thereof include boric acid; borate esters such as borate such as sodium borate and potassium borate; boron halide; acetate salts such as boryl acetate; boron sulfide; and borax. Among these boron compounds, it is preferable to use water-soluble boron compounds, especially boric acid, sodium borate, potassium borate, and borax.

(C) Other Components In the method for treating muddy water of the present invention, pulp fibers, sodium polyacrylate, and the like are added as optional components in addition to the above-mentioned components as long as the object of the present invention is not impaired. You can also.

(3) Compounding method (a) Addition of natural gum The compounding of natural gum in the method for treating muddy water of the present invention can also be carried out by adding finely divided natural gum as it is and thoroughly stirring and mixing. However, a method of mixing a natural gum with water to prepare a natural gum aqueous solution and then mixing the natural gum aqueous solution with the above-mentioned muddy water is a preferable method because it is easy to uniformly mix with the muddy water.

Preparation of Natural Gum Aqueous Solution The above natural gum is mixed with water to prepare a natural gum aqueous solution.
It can be prepared by adding parts by weight, preferably 80 to 120 parts by weight, and stirring and mixing under a temperature condition of generally 5 to 50 ° C, preferably 10 to 30 ° C. For the preparation of the natural gum aqueous solution, glyoxal or the like is preferably blended as a dissolution promoter. Further, other compounding agents such as sodium polyacrylate may be added.

The amount of the natural gum is generally 0.05 to 0.3 parts by weight, preferably 0.1 to 100 parts by weight, based on 100 parts by weight of the muddy water.
0.3 parts by weight, particularly preferably 0.15 to 0.25 parts by weight. If the amount of the natural gum is significantly less than the above range, the strength of the aggregate block becomes insufficient,
Further, if the amount is excessively large, the whole treated muddy water gels and loses cohesiveness, which is not preferable.

Muddy Water / Natural Gum Mixture The muddy water / natural gum mixture obtained in this way has a viscosity of 2 to 10 poise, not too large in viscosity, and shows a liquid state with good fluidity. Gum can be easily mixed. However, in this state, the sediment suspended and dissolved in the muddy water is considered to be in a state of being adsorbed on the surface of the polymer of the natural gum, but the state in which the high-molecular-weight natural gum itself has not been aggregated yet To be
It is in a state where it passes through the filter even after filtration.

(B) Compounding of boron compound In the method for treating muddy water of the present invention, the compounding of the boron compound is as follows:
This can also be performed by adding the finely divided boron compound as it is and stirring and mixing well. However, after the boron compound is mixed with water to prepare a boron compound aqueous solution, the boron compound aqueous solution is mixed with the above-mentioned muddy water / natural water. The method of mixing with the gum mixture is a preferred method because it is easy to uniformly mix with the muddy water / natural gum mixture. The compounding of the boron compound is as follows:
Although a method of mixing with the above-mentioned muddy water / natural gum mixture is generally used, it is also possible to mix a boron compound and muddy water before mixing the natural gum with muddy water. In any order, substantially the same effect can be obtained.

Preparation of Boron Compound Aqueous Solution The above boron compound is mixed with water to prepare a boron compound aqueous solution.
It can be prepared by adding 200 parts by weight, preferably 100 to 200 parts by weight, and stirring and mixing under a temperature condition of generally 5 to 50 ° C, preferably 10 to 30 ° C.

The compounding amount of the boron compound The compounding amount of the boron compound is generally 0.05 to 0.5 parts by weight, preferably 0.0 to 100 parts by weight of the muddy water.
It is in the range of 5 to 0.2 parts by weight, particularly preferably 0.1 to 0.2 parts by weight. Also, Polymer Chemistry, Vol. 11, No. 105, pp. 23-27, describes that natural gums are crosslinked by adding a small amount of a boron compound to 1 part by weight of natural gum to form a strong rubbery gel. However, the rubber-like gel cross-linked in such a blending amount is an independent gel, which is not broken even by external pressure, and cannot dehydrate water taken in the rubber-like gel. . Therefore, the compounding amount of the boron compound in the present invention is 10 to 200 parts by weight, preferably 20 to 150 parts by weight, particularly preferably 50 to 10 parts by weight based on 100 parts by weight of the natural gum.
It is preferable to set the range to 0 parts by weight. Therefore, when the compounding amount of the boron compound with respect to the natural gum is less than the above range, the rubber-like elastic gel formed is of a hard and independent shape, so that water in the gel cannot be dehydrated, and When the amount of the boron compound in the natural gum exceeds the above range, the natural gum is insolubilized and the water in the rubber-like elastic gel formed cannot be dehydrated.

Muddy water / Natural gum / boron compound mixed liquid The muddy water / natural gum / boron compound mixed liquid produced by adding / mixing a boron compound to the above-mentioned muddy water / natural gum mixed liquid has an amount of boron compound added. Although the rubber-like elastic gel is formed in a small initial stage, if the boron compound is further added and stirred, the rubber-like elastic gel is fragmented, and as a result, the viscosity of the mixed solution gradually decreases, and the low stirring is performed. The mixture can be easily stirred even by force, and a large floc is generated, and the water in the gel becomes a granular solid which is easily dehydrated. The generated granular solid has a muddy water floc size of 0.1 to 2 mm that is agglomerated using a normal aggregating agent.
In general, the shape is extremely large, such as about 3 to 10 mm, preferably about 5 to 50 mm, and
Since it is a hard floc, it can be easily separated from clear water by filtration or the like.

(4) Separation / removal of water (filtration) Since the particulate solid is in a state in which earth and sand suspended and dissolved in muddy water is adsorbed on the surface of the polymer of natural gum, a filter press is used. Floating and dissolving in muddy water by separating the granular solids and clarified water by filtering with a relatively coarse mesh such as a belt press, centrifugal separation, vibrating sieve or cloth, etc. Soil and sand can be removed together with natural gum. The air permeability is 5 to 50 in the conventional filter press, and 5 to 50 in the belt press.
Although the thing of 0 to 300 was used, such a fine thing can be used in the method of the present invention,
Since the separation ability is reduced in the case of such a particle size, in order to increase the separation ability, a filter cloth having a mesh size or more, preferably a filter press having a permeability of 100 or more, particularly preferably a permeability of about 200 to 300 is used. Is done.
In a belt press, a filter cloth having an air permeability of 50 or more, particularly preferably about 100 to 200, is used. Most preferably, it is good to carry out with a sieve of about 200 to 300 mesh.

(5) Transportation and Disposal The above-mentioned granular solid matter from which water has been removed is collected, transported by a dump truck or the like to a landfill site, an industrial waste disposal site, and discarded. However, since the volume of the particulate solid is remarkably reduced to 1/2 to 1/10 of the volume of the muddy water before treatment, not only the transportation cost can be saved, but also the landfill and industrial waste treatment land can be saved. Can be used for a long time. Further, since natural gum in muddy water buried in landfills and industrial waste disposal sites is a natural product, it is not decomposed by microorganisms in the soil and remains.

[II] Mud Water Treatment Apparatus A mud water treatment apparatus used in the method for treating muddy water of the present invention will be specifically described below with reference to the drawings, with reference to an embodiment thereof. FIG. 1 is a plan view of a muddy water treatment device used in the muddy water treatment method of the present invention, and FIG.
FIG. 3 is a left side view thereof.

As shown in FIG. 1, the muddy water treatment apparatus 1 used in the muddy water treatment method of the present invention basically includes a line mixer 2, a reaction tank 3 having a stirrer 3a, a vibrating sieve 4, and a control panel 5 The muddy water treatment apparatus 1 treats muddy water 6 discharged from a construction site, continuously separates and removes water, and recovers it as a solid content such as earth and sand having a low water content. . First, the muddy water 6 discharged from the construction site is supplied from a muddy water supply port 7, mixed with the natural gum aqueous solution 9 supplied from a natural gum aqueous solution supply port 8 in the line mixer 2, and further mixed with a boron compound. It is mixed in the line mixer 2 with the boron compound aqueous solution 11 supplied from the aqueous solution supply port 10 to form a muddy water / natural gum / boron compound mixed liquid 12. And this mixture 1
2 and water 14 supplied by a dilution pump 13 are mixed and diluted, and the diluted mixed liquid 12 is supplied to a reaction tank 3 provided with a stirrer 3a. Reaction tank 3 equipped with this stirrer 3a
The mixed solution 12 that is sufficiently stirred and mixed in the reaction vessel 3
In the inside, the rubbery elastic gel is formed or divided by a boron compound to finally obtain a granular solid 15. Next, the processing liquid containing the generated particulate solids 15 is discharged from the upper part of the reaction tank 3 and is discharged onto the vibrating sieve 4 vibrated by the motor 16. In the vibrating sieve 4, the water 17 which does not contain earth and sand which has passed through the mesh is temporarily stored in a storage tank 18 arranged below the vibrating sieve 4 and then discharged to a river or a sewer. On the other hand, the granular solid matter 15 from which the water has been removed is collected, transported by a dump truck or the like to a landfill site, an industrial waste disposal site, and discarded.

[0026]

【Example】

Example 1 Excavation was performed at a subway construction site using a drilling fluid containing 10% by weight of Gunma 250 mesh bentonite and 0.1% by weight of sodium nitrohumate as a dispersant, and the specific gravity of 1.23 was discharged. 25 wt. of an aqueous solution containing 1.0 wt.% guar gum prepared by separately dissolving guar gum in 100 wt. parts of a pH 12.1 bentonite-containing muddy water (cement content 5 wt.%, slime content 32 wt.%) Was added and mixed thoroughly at room temperature for 1 minute.
Next, 20 parts by weight of an aqueous solution containing 1.6% by weight of sodium borate, which was separately prepared by dissolving sodium borate in water, was added to the stirring liquid, and the mixture was sufficiently stirred and mixed at room temperature for 2 minutes. At this time, after the stirring was started, the mixture became a rubber-like elastic gel and increased in viscosity, but thereafter, the viscosity of the gel became weak and large flocs were generated. Then, the resulting solution is placed on a generally commercially available insect repellent net made of plastic (mesh interval: 1 mm × 1 mm), squeezed by hand, and filtered to remove a solid content having a water content of 48.7% by weight. Obtained. At this time, the floc was a large floc having a mesh size of 1 to 7 mm and a diameter of 4 to 7 mm so as not to come out of the gap between the plastic insect repellent nets of 1 mm × 1 mm, and could be easily separated from water. Table 1 shows the obtained results.

Example 2 A drilling solution containing 10% by weight of 250 mesh bentonite from Gunma and 0.1% by weight of CMC as a thickener was excavated by a shield method at a sewage works site and discharged. Bentonite-containing mud having specific gravity of 1.16 and pH of 11.0 (cement content: 0.5% by weight, slime content: 2
15 parts by weight of an aqueous solution containing 1.0% by weight of guar gum separately prepared by dissolving guar gum in water was added to 100 parts by weight of 6% by weight), and the mixture was sufficiently stirred and mixed at room temperature for 1 minute. Next, 25 parts by weight of an aqueous solution containing 1.6% by weight of sodium borate separately prepared by dissolving sodium borate in water was added to the stirring liquid, and the mixture was sufficiently stirred and mixed at room temperature for 2 minutes. At this time, after the stirring was started, the mixture became a rubber-like elastic gel and increased in viscosity, but thereafter, the viscosity of the gel became weak and large flocs were generated. The resulting liquid was placed on a generally commercially available insect repellent net made of plastic (mesh interval: 1 mm × 1 mm), and was then squeezed and filtered by hand to obtain a solid having a water content of 53% by weight. .
At this time, the floc was a large floc having a mesh size of 1 to 8 mm and a diameter of 4 to 8 mm which did not come out of a gap between the plastic insect nets having a mesh interval of 1 mm × 1 mm, and could be easily separated from water. Table 1 shows the obtained results.

Example 3 Specific gravity 1.43, pH 9.5 collected from the bottom of a park pond
15 parts by weight of an aqueous solution containing 1.0% by weight of guar gum prepared by separately dissolving guar gum in water is added to 100 parts by weight of sludge containing the silt clay-based organic material described above, and sufficiently stirred at room temperature for 1 minute. And mixed. Next, 20 parts by weight of an aqueous solution containing 1.6% by weight of sodium borate, which was separately prepared by dissolving sodium borate in water, was added to the stirring liquid, and the mixture was sufficiently stirred and mixed at room temperature for 2 minutes. At this time, after the stirring was started, the mixture became a rubber-like elastic gel and increased in viscosity, but thereafter, the viscosity of the gel became weak and large flocs were generated. Then, this product solution is generally used as a commercially available plastic insect repellent net (mesh interval: 1 mm × 1).
mm), the mixture was squeezed by hand and filtered to obtain a solid having a water content of 58% by weight. At this time, the flock was a hard flock having a mesh interval of 1 mm × 1 mm so as not to come out of a gap between the plastic insect repellent nets and a large flock having a diameter of 3 to 6 mm, and could be easily separated from water. Table 1 shows the obtained results.

Example 4 A drilling fluid containing 10% by weight of 250 mesh bentonite from Gunma and 0.1% by weight of sodium nitrohumate as a dispersant was excavated at a subway construction site, and the specific gravity discharged was 1 Sodium borate 1.6 wt% separately prepared by dissolving sodium borate in water with respect to 100 wt% of a bentonite-containing mud (pH: 12.1; cement content: 5 wt%, slime content: 32 wt%) 7.5 parts by weight of the aqueous solution was added, and the mixture was sufficiently stirred and mixed at room temperature for 2 minutes. Next, 30 parts by weight of an aqueous solution containing 1.0% by weight of guar gum prepared by separately dissolving guar gum in water was added to the stirring liquid, and the mixture was sufficiently stirred and mixed at room temperature for 2 minutes. At this time, after the stirring was started, the mixture became a rubber-like elastic gel and increased in viscosity, but thereafter, the viscosity of the gel became weak and large flocs were generated. Then, the resulting solution is placed on a generally commercially available insect repellent net made of plastic (mesh interval: 1 mm × 1 mm), squeezed by hand, and filtered to remove a solid content having a water content of 59.0% by weight. Obtained.
At this time, the floc was a large floc having a mesh size of 1 to 15 mm and a diameter of 5 to 15 mm, which did not come out of the gap between the plastic insect nets having a mesh interval of 1 mm × 1 mm, and could be easily separated from water. Table 1 shows the obtained results.

Comparative Examples 1-2 The muddy water treatment was performed in the same manner as in Example 1 except that the amounts of guar gum and sodium borate were changed. Table 1 shows the obtained results.

Comparative Examples 3 and 4 Mud water treatment was performed in the same manner as in Example 1 except that sodium polyacrylate was used instead of guar gum, and PAC (polyaluminum chloride) was used instead of sodium borate. . Table 1 shows the obtained results.

[0032]

[Table 1]

[0033]

The method for treating muddy water according to the present invention is as follows.
Large and hard flocs can be formed by simple operations such as adding two types of chemicals to muddy water of various properties. Since the volume can be significantly reduced to 1/2 to 1/10 of the volume of the waste, there is an advantage that not only the transportation cost can be saved but also the landfill and the industrial waste disposal land can be used for a long time. .

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment of a muddy water treatment apparatus used in the muddy water treatment method of the present invention.

FIG. 2 is a front view of the muddy water treatment apparatus of FIG.

FIG. 3 is a left side view of the muddy water treatment apparatus of FIG.

[Description of Signs] 1 Muddy water treatment device 2 Line mixer 3 Reaction tank 3a Stirrer 4 Vibrating sieve 5 Control panel 6 Muddy water 7 Muddy water supply port 8 Natural gum aqueous solution supply port 9 Natural gum aqueous solution 10 Boron compound aqueous solution supply port 11 Boron compound aqueous solution 12 Muddy water / Natural gum / boron compound mixture 13 Dilution pump 14 Water 15 Granular solid matter 16 Motor 17 Moisture free of earth and sand 18 Storage tank

Claims (3)

(57) [Claims] 1. A method of coagulating solids in mud and separating and removing water by filtration , wherein a natural gum and a boron compound are added to the mud. Method. 2. The amount of the natural gum added to the muddy water is:
The method for treating mud according to claim 1 , wherein the amount is 0.05 to 0.3 parts by weight based on 100 parts by weight of mud. The amount of wherein the boron compound is added to the muddy water, 10 to 100 parts by weight with respect to the natural gum 100 parts by weight, processing method mud according to claim 1 or 2.