JP2006000784A - Method and system of treating slurry and fango - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To treat fungo or highly concentrated electrolyte-containing waste slurry generated in a civil construction site like soil improvement, more efficiently and more inexpensively than the conventional method. <P>SOLUTION: The slurry produced in the civil construction site is sent to a mixing apparatus 11 from a slurry storing tank 3 without diluting. At the same time, a given dispersing coagulant is sent to the mixing apparatus 11 in a formulated concentrate state without diluting, and added to the slurry for mixing. At least one or more kinds of surfactants selected from nonionic, anionic and cationic groups are added and mixed in advance in a production process at a factory (or at the site before coagulation) to the coagulant. In this way, the slurry can be coagulated in a short time without increasing the volume of the slurry to be treated, to form flock. As a result, the efficiency of a dewatering unit can be greatly increased, for example, and the cost can be reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a predetermined water-in-oil emulsion and / or a dispersion in a salt aqueous solution for mud soil generated from underground civil engineering work sites such as ground improvement and high-concentration mud water containing an electrolyte such as an alkaline substance. By treating with a flocculant composed of the following (generally referred to as “dispersion type flocculant”) and metal salts, followed by solid-liquid separation treatment, It belongs to the field of technology for reusing cake and treated water after volume reduction and dehydration.

  The present invention is provided in view of the first and second backgrounds described below.

[First background]
Currently, mud soil generated from underground civil engineering works such as ground improvement and high-concentration waste water containing electrolytes such as alkaline substances are mainly disposed of by the methods listed in (1) to (3) below. .
(1) Without any treatment, transport it to a waste disposal site with a vacuum vehicle in the discharged state and discard it.
(2) The discharged mud, mud and highly hydrous soil are settled and separated into a supernatant and earth and sand. The separated earth and sand are consolidated and then transported to a waste disposal site for disposal.
(3) Add and mix flocculant (organic polymer flocculant) to the discharged mud, mud, and highly hydrous soil, and further naturally separate into supernatant water and earth and sand using gravity. The separated solid content is transported to a waste disposal site and discarded. Further, the separated supernatant liquid is reused as construction water or discharged after adjusting the pH value appropriately.

  However, the methods described in the above (1) to (3), which have been conventionally performed, have the following problems.

  The method (1) has a problem in terms of economy when there is a large amount to be processed. Moreover, when a large amount of waste water is disposed of, it is difficult to secure a disposal site, and there is a problem from the viewpoint of environmental load.

  In the method (2), when the high water content contains a large amount of fine particles, precipitation / separation treatment (treatment for separating the supernatant liquid and earth and sand) cannot be performed. Even if precipitation / separation can be performed, a large-capacity sedimentation tank is required, and the effect of reducing the amount of highly hydrous soil is small.

  In the above method (3), the organic polymer flocculant added to and mixed with highly hydrous soil is used after being diluted in advance with fresh water in order to maximize its effect. . And when diluting, the density | concentration is set to about 0.1 to 0.2% (weight) with respect to fresh water. However, such a method has a problem in terms of construction cost because it requires an extra cost for securing the necessary amount of fresh water used for dilution. In addition, since the entire processing amount is increased by diluting with fresh water, there is a problem that not only the burden is increased and the effect and efficiency of the dehydrating machine are reduced, but also the processing cost is increased.

[Second background]
In various construction sites, natural dehydration using a polymer flocculant and mechanical dehydration using a dehydrating machine are performed.

  However, for muddy water and high water content containing electrolytes such as cement, an effective technique for treating agents and dehydration machines has not been provided. For this reason, it has hardly been reused after dehydration treatment or the like on highly hydrous mud containing electrolyte such as cement.

  However, under the present situation where the disposal site of industrial waste is decreasing, the treatment cost for muddy water and high water content is also becoming expensive, so the reuse of muddy water and high water content after treatment is strongly desired. .

  Therefore, in view of the above-described problems of the prior art, the object of the present invention is to reduce the cost of high-concentration wastewater containing mud and electrolyte generated in large quantities in the civil engineering work site such as ground improvement as compared with the prior art. In addition, it is an object of the present invention to provide a method and system capable of efficiently processing.

  In addition, another object of the present invention is to provide a predetermined treatment for muddy water and highly hydrous soil discharged at a civil engineering work site in view of the situation where industrial waste disposal sites are decreasing. It is to recycle all or part of it, to reduce the construction cost of the entire civil engineering work, and to reduce the burden on the environment.

  The object described above is achieved by the present invention described in the following (1) to (6).

(1) A flocculant used when treating an object to be treated consisting of at least one of mud and electrolyte containing electrolyte generated at a civil engineering work site,
At least one or more surfactants selected from nonionic, anionic, and cationic groups are pre-added and mixed in the manufacturing process in the factory, or the civil engineering work site before agglomeration treatment on the workpiece A dispersion type flocculant comprising a water-in-oil emulsion and / or a dispersion in an aqueous salt solution added and mixed in the method.

(2) For processing using the dispersion type flocculant described in the above (1) without diluting an object to be processed consisting of at least one of mud containing electrolyte and mud generated at a civil engineering work site A method,
A method for treating muddy water and mud, comprising a step of adding and mixing the dispersion-type flocculant in the state of a stock solution without diluting it to cause an agglomeration reaction.

(3) Furthermore, it dissolves in an acid that is a compound having a hydrogen atom that can be substituted with a metal or a basic group for the object to be treated which has been aggregated and flocked through the addition and mixing steps of the dispersion type flocculant A step of adding and mixing the prepared metal salts,
The above (2), wherein the metal salt is added and mixed to lower the pH value of the object to be treated and to hydrophobize the water adsorbed and absorbed by the dispersion type flocculant in the flocs flocs. ) Method for treating muddy water and mud.

  (4) The method further includes a step of separating the object to be processed into a cake and moisture by performing a dehydration process on the object to be processed after the addition and mixing steps of the metal salts. The method for treating mud and mud according to (3) above.

(5) Furthermore, for all or part of the cake obtained through the dehydration step,
Any of the process of discarding as it is, the process of discarding after applying a neutral solidification process, and the process of reusing as a soil structure material after improving with a quick-setting agent or a porous inorganic mineral The method for treating muddy water and mud according to (4) above, comprising a step of selectively performing the treatment.

(6) A system for treating an object to be treated comprising at least one of mud and electrolyte containing an electrolyte generated at a civil engineering work site using the dispersion type flocculant described in (1) above. ,
A first container containing the dispersion type flocculant;
A second container containing a metal salt dissolved in an acid which is a compound having a hydrogen atom that can be substituted with a metal or basic group;
The mud storage means provided at the civil engineering work site and the first container are connected, the workpiece to be fed from the mud storage means, and the dispersion fed from the first container A mixing device for mixing the liquid type flocculant;
The mixing apparatus and the second container are connected, and the mixed object to be processed fed from the mixing apparatus and the metal salts fed from the second container are mixed and stirred. A stirring device for,
A dehydrating device connected to the stirring device, for performing a dehydration process on the stirred object to be processed fed from the stirring device;
The object to be treated is supplied to the mixing device from the mud storage means without being diluted and subjected to a mixing process,
The dispersion type flocculant is fed from the first container to the mixing device without being diluted, and is added to and mixed with the object to be processed. A muddy water and muddy soil treatment system.

  According to the present invention described above, the predetermined dispersion liquid type flocculant is added to the mud water discharged at the civil engineering work site for ground improvement or the like while being discharged (that is, without being diluted). It has become. In addition, this dispersion type flocculant is added in a small amount to the waste mud water or the like while remaining in the state of the stock solution (that is, without being diluted). Therefore, according to such a feature, it is possible to aggregate and form flocs in a short time without increasing the volume of muddy water to be treated. As a result, for example, it is possible to significantly increase the efficiency of the dehydrating machine, and achieve special effects such as enabling cost reduction.

  In addition, to the dispersion type flocculant used in the present invention, one or two or more predetermined types of surfactants are added in advance in a manufacturing process in a factory (or at a construction site before agglomeration treatment with respect to waste mud water or the like). It has come to be. Thereby, the dispersion-type flocculant to be added can be mixed and dissolved in the muddy water or the like in a small amount and in a short time.

  In addition, according to the present invention, predetermined metal salts are added to the aggregated mud drainage water and the like in order to improve hydrophobicity. Thereby, since the said mud water etc. can be solid-liquid separated into a water | moisture content and a cake in a short time, it becomes possible to aim at the reduction | decrease of waste mud water efficiently.

  In addition, when the cake obtained in the solid-liquid separation process is subjected to neutral solidification, etc., it can be reused for earth structure materials, etc., so that the disposal cost can be reduced, etc. A special effect is also achieved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings and tables.

[Configuration of wastewater treatment system]
First, based on FIG. 1, schematic structure of the waste mud water treatment system utilized when implementing waste water treatment is demonstrated. FIG. 1 is a diagram showing a schematic configuration of a wastewater treatment system 1.

  The waste water treatment system (muddy water, mud treatment system) 1 used in the present invention mainly includes a mixing device 11, a stirring device 13, a dehydration device 15, and a first container 21 that contains a dispersion type flocculant. And a second container 22 for storing metal salts.

  In the wastewater treatment system 1, the mixing device 11 is connected to a mud storage means (for example, a mud tank, a pit, etc.) provided at a civil engineering work site such as ground improvement work through a hose. Although the kind of mixing apparatus connected to the said mud storage means is not specifically limited, For example, a well-known static mixer etc. can be used.

  The mud storage means is adapted to store mud and mud (including highly hydrous soil) discharged in conjunction with ground improvement work. Hereinafter, “mud storage tank” will be given as an example of the mud storage means, and “mud water” will be given as an example of an object to be treated according to the present invention, and embodiments relating to the present invention will be described.

  In the middle of the hose between the mixing device 11 and the mud tank 3, a pump (not shown) for sending the discharged mud water in the mud tank 3 toward the mixing device 11 and the pump is sent by the pump. And a first flow rate management device 31 for adjusting the flow rate of the discharged mud water.

  Moreover, in addition to the mud storage tank 3, the 1st container 21 is connected to the mixing apparatus 11 via the hose. The first container 21 contains a dispersion type flocculant (details will be described later) that are to be sent out toward the mixing device 11. In the middle of the hose between the mixing device 11 and the first container 21, a second flow rate management device 32 for adjusting the flow rate of the dispersion type flocculant fed toward the mixing device 11 is provided. ing.

  Among the dispersion-type flocculants, for water-in-oil emulsions, at least one surfactant selected from nonionic, anionic, and cationic groups is used in the production process in the factory (or In addition, it is added and mixed in advance at the construction site before the coagulation treatment with respect to the waste mud water. The addition of the surfactant is performed for the purpose of mixing and dissolving the water-in-oil emulsion in a small amount and in a short time in the mud water. The surfactant is a low HLB (hydrophilic lipophilic balance) surfactant. Specifically, polyoxyethylene (20) sorbitan trioleate, polyoxyethylene (4) sorbitan monostearate, polyoxyethylene (5) sorbitan monooleate and the like are preferable. Moreover, the dispersion in salt aqueous solution can be dissolved in water as it is.

  The stirring device 13 is connected to the mixing device 11 via a hose. In addition, a second container 22 is connected to the stirring device 13 via a hose. The second container 22 contains metal salts (details will be described later) that are to be delivered to the stirring device 13. In the middle of the hose between the stirring device 13 and the second container 22, a third flow rate management device 33 for adjusting the flow rate of the metal salts sent toward the stirring device 13 is provided. In addition, the kind of stirring apparatus 13 is not specifically limited, It is possible to use the mixer generally used.

  A dehydrator (solid-liquid separator) 15 is connected to the agitator 13 via a hose. The kind of the said dehydrating apparatus is not specifically limited, For example, it is possible to use a well-known screw press machine.

[Process flow for workpieces]
Next, based on FIG.1 and FIG.2, the flow of the wastewater treatment using the wastewater treatment system 1 mentioned above is demonstrated in detail. FIG. 2 is a flowchart showing the flow of wastewater treatment using the wastewater treatment system 1 shown in FIG.

  Mud water discharged by civil engineering work such as ground improvement work is first stored in the mud tank 3. The wastewater stored in the mud storage tank 3 is sent out to the mixing device 11 by a pump without being diluted (step S1). In this process, the discharged mud water is sent through the first flow rate embedding device 31 while the flow rate is controlled.

At the same time, a predetermined amount (a small amount) of the dispersion type flocculant from the first container 21 is not diluted with the mixing device 11 via the second flow rate tube embedding device 32 as in the prior art. Then, the undiluted solution is delivered (step S3). And in the said mixing apparatus 11, the dispersion liquid type coagulant | flocculant and waste mud water are mixed (step S5). As a result, flocculation and flocking are performed in the waste mud water in a short time.
The ratio (mixing ratio) of the waste mud water to be mixed and the dispersion type flocculant is not particularly limited. For example, the content of the dispersion type flocculant per 1 m ^{3 of} the waste mud water is about 1 to 5 kg. Add and mix to the extent.

  After being mixed in the mixing device 11, the primary processed product (mixed waste mud water and dispersion type flocculant) that has been aggregated and flocked is sent to the stirring device 13. At the same time, a predetermined amount of metal salt is sent from the second container 22 to the stirring device 13 via the third flow rate embedding device 33 (step S7). And in the said stirring apparatus, a primary processed material and metal salts are mixed and stirred (step S9). And by addition of this metal salt, pH value falls and water in the aggregation floc hydrophobizes (hydrophobicity improves).

  Subsequently, the secondary processed product (mixed and stirred metal salt with respect to the primary processed product) is sent from the stirring device 13 to the dehydrating device 15. In the dehydrator 15, the hydrophobized floc is dehydrated. Then, after the dehydration process, the secondary processed product is solid-liquid separated into moisture and cake (step S11).

The whole or part of the “cake” obtained by the separation is selectively provided for disposal or use, for example, in any of the following (a) to (c).
(A) The cake obtained by separating is discarded as it is.
(B) Dispose after neutralization.
(C) Improve by using a quick setting agent or porous inorganic mineral and reuse it as a soil structure material.

On the other hand, all or part of the “moisture” obtained by the separation is subjected to, for example, the following treatment (d) or (e).
(D) Reuse as construction water.
(E) Discharge after adjusting the pH value appropriately.

[Details of dispersion type flocculant]
Next, the details of the dispersion type flocculant added to the discharged mud water will be described.

  The dispersion type flocculant used in the present invention is a material mainly composed of an organic polymer having an electrical adhesive force. This aggregating agent has a molecular weight of 1 million or more (preferably 2 million or more), and a water-in-oil emulsion or salt having a dispersed particle diameter of 100 μm or less made of an acrylic polymer having an ionization concentration of 0 to 100 mol%. A polymer flocculant having the form of a dispersion in an aqueous solution.

In addition, about the dispersion-type flocculent used by this invention, when a viscosity is too high, kneading | mixing will become non-uniform | heterogenous.
On the other hand, as seen in conventional flocculation treatment, when the polymer flocculant is used after being diluted with fresh water, a large amount of flocculant liquid is added to the waste mud water, resulting in a very high amount of waste mud water to be dehydrated. There is a problem that the load on the dehydrating apparatus increases as the number increases.
Therefore, the acrylic polymer flocculant dispersion liquid used in the present invention preferably has a viscosity of 10,000 mPas or less and a concentration of 10% or more. When the acrylic polymer flocculant dispersion liquid is configured as described above, it is possible to add the low-concentration dispersion polymer flocculant dispersion liquid as it is without diluting it.

  Next, specific polymers will be described. Nonionic polyacrylamide, anionic acrylic acid, methacrylic acid, itaconic acid, maleic acid, acrylamide 2-methylpropane sulfonic acid, vinyl sulfonic acid, styrene Examples thereof include homopolymers such as sulfonic acid and copolymers with acrylamide.

  As cationic properties, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminopropylacrylamide, dimethylaminopropylmethacrylamide, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloylaminopropyltrimethyl. Examples thereof include homopolymers such as ammonium chloride, methacryloylaminopropyltrimethylammonium chloride, acryloyl 2-hydroxypropyl chloride, methacryloyl 2-hydroxypropyl chloride, and copolymerization with acrylamide.

  Methods for producing such dispersions are known. Specifically, water-in-oil emulsions are described in JP-B No. 34-10644, JP-B No. 52-39417 and JP-B No. 55-45783. Yes. A method for producing a dispersion in an aqueous salt solution is described in JP-B No. 46-14907 and JP-A No. 62-20511.

  In the case of commercially available water-in-oil emulsions, the amount of surfactant is usually adjusted so that it dissolves in fresh water, but it dissolves in waste mud containing a large amount of clay and colloids. Hard to do. On the other hand, in the case of the present invention, since the kind and amount of the surfactant are appropriately adjusted, it is possible to quickly dissolve and to rapidly aggregate the sludge. Specifically, the amount of the surfactant is preferably about 0.5% to 30% with respect to the water-in-oil emulsion with respect to the total amount of the surfactant including the surfactant called a phase inversion agent.

  When the dispersion type flocculant described above is mixed with a highly hydrous soil, the soil particles in the highly hydrous soil are aggregated in a very short time. The soil particles are held firmly and the separation of water is reduced. However, when metal salts dissolved in acid are added here, they are hydrophobized to promote the separation of water and increase the amount of separated water.

[Details of metal salts]
The details of the metal salts will be described. Specific metal salts include aluminum chloride, sulfate band, ferrous sulfate, ferric chloride, calcium chloride and the like.

[Example]
Next, Table 1 below shows examples of indoor blending tests applied to sludge generated by the highly alkaline jet grout method (ground improvement method) considered to be the most difficult to agglomerate, and highly hydrous soil.

  As shown in Table 1 above, even if it is a highly hydrous soil generated by the jet grout method, the high hydrous soil can be separated into moisture and cake satisfactorily by applying the treatment according to the present invention. Was confirmed.

[Excellent effect achieved by the present invention]
According to the present invention described above, a predetermined dispersion liquid type flocculant is added to the discharged mud water or the like discharged at a civil engineering work site while being discharged (that is, without being diluted). . In addition, this dispersion type flocculant is added in a small amount to the waste mud water or the like while remaining in the state of the stock solution (that is, without being diluted). Therefore, according to such a feature, it is possible to aggregate and form flocs in a short time without increasing the volume of muddy water to be treated. As a result, for example, it is possible to significantly increase the efficiency of the dehydrating machine, and achieve special effects such as enabling cost reduction.

  In addition, to the dispersion type flocculant used in the present invention, one or two or more predetermined types of surfactants are added in advance in a manufacturing process in a factory (or at a construction site before agglomeration treatment with respect to waste mud water or the like). It has come to be. Thereby, the dispersion-type flocculant to be added can be mixed and dissolved in the muddy water or the like in a small amount and in a short time.

  In addition, according to the present invention, predetermined metal salts are added to the aggregated mud drainage water and the like in order to improve hydrophobicity. Thereby, since the said mud water etc. can be solid-liquid separated into a water | moisture content and a cake in a short time, it becomes possible to aim at the reduction | decrease of waste mud water efficiently.

  In addition, when the cake obtained in the solid-liquid separation process is subjected to neutral solidification, etc., it can be reused for earth structure materials, etc., so that the disposal cost can be reduced, etc. A special effect is also achieved.

  The muddy water and muddy soil treatment method and treatment system according to the present invention have been described in detail above. Note that the configuration of the present invention is not limited to the configuration of the above-described embodiment, and various modifications can be made within the scope of the invention described in the claims.

  The present invention is a method and system capable of treating a high-concentration waste mud containing a large amount of mud and electrolyte generated at a civil engineering work site such as ground improvement at a lower cost and more efficiently than conventional ones. It is used suitably for providing.

  In addition, in view of the situation where the disposal site of industrial waste is decreasing, the present invention performs a predetermined treatment on muddy water and highly hydrous soil discharged at a civil engineering construction site, and then all or one of them. It is used suitably for reusing a part, reducing the construction cost of the entire civil engineering work, and reducing the burden on the environment.

It is a figure which shows schematic structure of a wastewater treatment system. It is a flowchart which shows the flow of the wastewater treatment using the wastewater treatment system shown in FIG.

Explanation of symbols

1 Wastewater treatment system (muddy water, mud treatment system)
3 Mud storage tank (mud storage means)
DESCRIPTION OF SYMBOLS 11 Mixing device 13 Stirring device 15 Dehydrating device 21 1st container 22 2nd container 31 1st flow management device 32 2nd flow management device 33 3rd flow management device

Claims (6)

A flocculant used when treating an object to be treated consisting of mud generated at a civil engineering work site and mud containing electrolyte,
At least one or more surfactants selected from nonionic, anionic, and cationic groups are pre-added and mixed in the manufacturing process in the factory, or the civil engineering work site before agglomeration treatment on the workpiece A dispersion type flocculant comprising a water-in-oil emulsion and / or a dispersion in an aqueous salt solution added and mixed in the method. It is a method for processing using the dispersion type flocculant of Claim 1 without diluting the to-be-processed object which consists of at least any one of the mud and the muddy water containing electrolyte which generate | occur | produce in the civil engineering construction site, ,
A method for treating muddy water and mud, comprising a step of adding and mixing the dispersion-type flocculant in the state of a stock solution without diluting it to cause an agglomeration reaction. further,
Addition of metal salt dissolved in acid, which is a compound having a hydrogen atom that can be substituted for a metal or basic group, to the object to be treated which has been aggregated and flocked through the addition and mixing steps of the dispersion type flocculant , Including the step of mixing,
3. The metal salt is added and mixed to lower the pH value of the object to be treated and to hydrophobize water adsorbed and absorbed by the dispersion type flocculant in the flocs. The muddy water and mud disposal method described. further,
4. The method according to claim 3, further comprising a step of separating the object to be processed into a cake and moisture by performing a dehydration process on the object to be processed after the adding and mixing steps of the metal salts. Of muddy water and mud. further,
For all or part of the cake obtained through the dehydration step,
Any of the process of discarding as it is, the process of discarding after applying a neutral solidification process, and the process of reusing as a soil structure material after improving with a quick-setting agent or a porous inorganic mineral The method for treating muddy water and mud according to claim 4, further comprising a step of selectively performing the treatment. A system for treating an object to be treated comprising at least one of mud and electrolyte containing mud generated at a civil engineering work site using the dispersion type flocculant according to claim 1,
A first container containing the dispersion type flocculant;
A second container containing a metal salt dissolved in an acid which is a compound having a hydrogen atom that can be substituted with a metal or basic group;
The mud storage means provided at the civil engineering work site and the first container are connected, the workpiece to be fed from the mud storage means, and the dispersion fed from the first container A mixing device for mixing the liquid type flocculant;
The mixing apparatus and the second container are connected, and the mixed object to be processed fed from the mixing apparatus and the metal salts fed from the second container are mixed and stirred. A stirring device for,
A dehydrating device connected to the stirring device, for performing a dehydration process on the stirred object to be processed fed from the stirring device;
The object to be treated is supplied to the mixing device from the mud storage means without being diluted and subjected to a mixing process,
The dispersion type flocculant is fed from the first container to the mixing device without being diluted, and is added to and mixed with the object to be processed. A muddy water and muddy soil treatment system.

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