JP7105080B2 - Waste muddy water volume reduction treatment device and volume reduction treatment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a waste muddy water volume reduction treatment apparatus and a volume reduction treatment method, and in particular, waste muddy water containing contaminants such as fluorine, lead, arsenic, etc. generated by the slurry shield construction method can be reduced at the construction site. The present invention relates to a technique that is suitably applied for solubilization.

When constructing a tunnel using the shield construction method on ground that is likely to contain contaminants such as fluorine, lead, and arsenic, there is a risk that a dewatered cake that exceeds environmental standards will be produced. For this reason, by making the excavated soil muddy, it is possible to easily extract and separate contaminants (fluorine, lead, arsenic, etc.). Measures to extract and separate contaminants are being considered.

Here, in the muddy shield construction method, there are the following two methods for extracting and separating contaminants (fluorine, lead, arsenic, etc.) from waste muddy water. The first method is a method of adding iron powder to waste muddy water to adsorb soluble contaminants (such as soluble fluorine, lead, arsenic, etc.), and then recovering the iron powder with the adsorbed contaminants. be. The second method is to add an agent that promotes the extraction of contaminants (fluorine, lead, arsenic, etc.) to the waste mud, and then dehydrate the waste mud to obtain water in which the contaminants (fluorine, lead, arsenic, etc.) are dissolved. is a method of recovering

In addition, a method of insolubilizing contaminants (fluorine, lead, arsenic, etc.) while excavating is also being considered by adopting the mud pressure shield construction method and supplying iron powder and insolubilizing materials to the working face.

As described above, various techniques have been proposed for methods and facilities for treating contaminated soil (for example, see Patent Document 1, Patent Document 2, and Patent Document 3). The technique described in Patent Literature 1 is a method for separating arsenic from various arsenic-containing aqueous solutions such as industrial waste water and nickel sulfate aqueous solutions that are intermediate raw materials for nickel chemical products used as electronic materials. That is, the technique described in Patent Document 1 is to add a metallic iron powder to an arsenic-containing aqueous solution and stir and mix it, or to pass the arsenic-containing aqueous solution through a column or the like filled with the metallic iron powder, to obtain the metallic iron powder. This is a technique for recovering metallic iron powder in which arsenic is adsorbed as iron compounds by solid-liquid separation after reacting arsenic on the surface. Here, it is stated that the particle size of the metallic iron powder is 1 mm or less, preferably adjusted to 10 μm to 1 mm.

The technique described in Patent Literature 2 relates to a purification material for purifying contaminated soil containing heavy metals such as fluorine, boron, arsenic, chromium, lead, and selenium. That is, the purification material used in the technique described in Patent Document 2 is obtained by attaching the hydroxide or oxide of the rare earth element to the surface of the metal iron powder, thereby removing the same amount of the hydroxide or oxide of the rare earth element. It is said that the ability of the hydroxide or oxide of the rare earth element to adsorb heavy metals can be improved more than when it is used alone.

The technology described in Patent Document 3 is a technology for insolubilizing the excavated and discharged heavy metal contaminated soil at the current location when treating the heavy metal contaminated soil generated along with closed shield tunnel construction. The insolubilizing agent is injected from the front face of the excavation face of the closed shield tunnel into the heavy metal contaminated soil at the position and stirred and mixed on the cutter face. Furthermore, it is possible to ensure the standard of insolubilization by promoting the remixing and insolubilization reaction in the discharge pipe.

JP 2008-155105 A JP 2012-51967 A JP 2006-316599 A

However, for the above-described first method, it is necessary to comprehensively examine the entire apparatus from the generation of the shield drained mud to the generation of the dehydrated cake. In addition, with regard to equipment for recovering iron powder that has adsorbed arsenic, which is a contaminant, there are many cases in which equipment with a small processing capacity relative to the scale of the equipment is being considered. In order to treat muddy water, there are various problems, such as the need to introduce a large amount of iron powder recovery equipment at an unrealistic level.

In addition, in the second method described above, since the added extraction material remains in the dehydrated cake, the future safety of the dehydrated cake cannot be ensured. There are various problems such as

Furthermore, when the mud pressure shield construction method is adopted, contaminants (fluorine, lead, arsenic, etc.) must be insolubilized, and the treated soil contains contaminants (fluorine, lead, arsenic, etc.). must be managed permanently.

The present invention has been proposed in view of the above-mentioned circumstances. An object of the present invention is to provide a waste muddy water volume reduction apparatus and a waste muddy water volume reduction method capable of efficiently and appropriately treating muddy water to be treated even when it is generated.

In order to achieve the above-described objects, the waste muddy water volume reduction treatment apparatus and volume reduction treatment method of the present invention have the following features. That is, the apparatus for reducing the volume of waste muddy water of the present invention is an apparatus for reducing the volume of waste muddy water containing contaminants including at least fluorine, lead, and arsenic. It has a group of devices used in

The apparatus for reducing the volume of waste mud according to the present invention comprises, as main components, a clay crushing apparatus for crushing clay lumps contained in waste mud, and sand contained in the waste mud after crushing the clay lumps. A sand washing classifier that washes and removes iron, a pH adjustment device that adjusts the waste mud from which sand has been removed to pH 5 to 5.5, and a porous iron in the pH-adjusted waste mud Waste mud containing no iron powder and iron powder with adsorbed contaminants are mixed using an iron powder addition device that adds powder and iron powder subjected to surface oxidation treatment at a ratio of 1:1, and a cyclone. An iron powder separator for gravity separation and a dewatering apparatus for dewatering the waste muddy water after the iron powder is separated are provided.

In addition, the sand washing and classifying device is a device that sucks waste muddy water from crushed clay lumps, discharges it at high pressure together with compressed air, and makes it collide with a plate-shaped member to separate the fine particles adhering to the sand. preferably contains

Furthermore, other equipment necessary for volume reduction of waste muddy water can be provided before or after each device. Other devices are detailed later as specific examples.

The waste mud volume reduction treatment method of the present invention is a method for volume reduction treatment of waste mud mixed with contaminants including at least fluorine, lead, and arsenic, comprising a clay crushing step and a sand washing and classification step. , a pH adjustment step, an iron powder addition step, an iron powder adsorption classification step, and a dehydration treatment step. For each step, an apparatus that constitutes the above-described volume reduction treatment apparatus can be used, but an apparatus other than the above-described apparatus may be used to carry out the treatment specified in each step.

The clay crushing process is a process for crushing clay lumps contained in the waste muddy water. The sand washing and classifying process is a process for washing and removing sand contained in the waste muddy water from which clay lumps have been crushed. The pH adjustment step is a step for adjusting the waste muddy water from which sand has been removed to pH 5 to 5.5 . The iron powder addition step is a step of adding porous iron powder and iron powder subjected to surface oxidation treatment to pH-adjusted waste mud at a ratio of 1:1. The iron powder adsorption and classification process is a process for adsorbing contaminants to iron powder and using a cyclone to separate waste muddy water containing no iron powder from iron powder with adsorbed contaminants by specific gravity. The dehydration process is a process for dehydrating the waste muddy water after the iron powder has been separated.

In the sand washing and classifying step, it is preferable to suck the waste muddy water from which clay lumps have been crushed, discharge it at high pressure together with compressed air, and cause it to collide with a plate-like member to separate the fine particles adhering to the sand. .

According to the apparatus for reducing the volume of waste muddy water and the method for reducing the volume of waste muddy water according to the present invention, for example, soil containing naturally occurring contaminants such as fluorine, lead, and arsenic generated in muddy shield construction can be removed at a construction site. During the volume reduction process, even if a large amount of waste mud containing these contaminants is generated, efficient and appropriate can be processed.

An explanatory view showing the configuration of a waste muddy volume reduction treatment apparatus according to an embodiment of the present invention. 1 is a flow chart of a waste muddy volume reduction treatment method according to an embodiment of the present invention;

Hereinafter, embodiments of a volume reduction treatment apparatus and a volume reduction treatment method for waste muddy water according to the present invention will be described with reference to the drawings. 1 and 2 illustrate a volume reduction treatment apparatus and a volume reduction treatment method for waste muddy water according to an embodiment of the present invention. FIG. 1 is an explanatory diagram showing the configuration of the volume reduction treatment apparatus, and FIG. is a flow chart of a volume reduction treatment method.

<Overview of Volume Reduction Treatment Apparatus and Volume Reduction Treatment Method>
A waste muddy water volume reduction processing apparatus and a volume reduction processing method according to an embodiment of the present invention are for volume reduction processing of contaminated muddy water containing fluorine, lead, arsenic, etc. generated in, for example, slurry shield construction. Apparatus and method, as shown in FIG. 1, a group of apparatuses disposed after the shield machine 10, which includes a clay crusher (crusher 30), a gravel classifier (second No. 2 classifier 50), sand cleaning classifier (third classifier 60 including cyclone 70, and each device installed in sand cleaning tank 80), pH adjusting device 110, iron powder adding device 150, cyclone It is equipped with an iron powder separator 160 and a dehydrator (filter press 190), and these devices are used to reduce the volume of waste muddy water.

It should be noted that the volume reduction treatment apparatus and volume reduction treatment method according to the present invention can be used not only for slurry shield construction, but also for surplus soil generated during mud pressure shield construction and ordinary excavation work by performing appropriate pretreatment. It can also be applied to

In addition, in the waste muddy water volume reduction treatment apparatus and volume reduction treatment method of the present invention, waste muddy water mixed with contaminants such as fluorine, lead, and arsenic is assumed to be treated, but contaminants other than these are assumed. (eg, boron, chromium, lead, selenium, etc.) can also be applied to waste muddy water. In the embodiments described below, it is assumed that the waste mud contains fluorine, lead, arsenic, etc., and may further contain other contaminants. will be explained as

<Washing and classification of sand / Classification of iron powder>
As shown in FIG. 1, the volume reduction treatment apparatus and volume reduction treatment method for waste muddy water of the present invention includes, as main steps, a sand cleaning and classification step and an iron powder adsorption and classification step.

The sand washing and classification step is a particularly important step in the waste muddy water volume reduction treatment apparatus and volume reduction treatment method of the present invention. Subsequent processing can be simplified. The main devices used in this sand washing and classifying process are the third classifying device 60 including the cyclone 70 and each device installed in the sand washing tank 80 .

The iron powder adsorption and classification step is a simplified step compared to the conventional technology in the waste mud volume reduction treatment apparatus and volume reduction treatment method of the present invention, and sand content in the waste mud is removed in advance. Therefore, there is no need for a magnetic separation device such as a drum type for separating the iron powder. A main device used in this iron powder classification process is an iron powder separator 160 using a cyclone.

<Clay Crusher>
The clay crushing device is a device for crushing clay lumps contained in the waste muddy water, and is constituted by a crusher 30 in this embodiment. Also, the first classifying device 20 is arranged before the crusher 30 , and the desludging tank 40 is arranged after the crusher 30 and the first classifying device 20 . The under-sieved material from the first classifier 20 is stored in the desludging tank 40 , and the residual material from the first classifier 20 is pulverized by the crusher 30 and then stored in the desludging tank 40 .

In general shield construction, waste muddy water discharged from the shield machine 10 is often sifted into sand exceeding 2 mm and fine particles of 2 mm or less, and the sieved residue is treated as sand as surplus soil. When excavating ground containing naturally occurring fluorine, lead, arsenic, etc., it is highly likely that the soil to be excavated will be soil. The possibility of inclusion cannot be ruled out. For this reason, in this embodiment, a clay crushing device for crushing the sieve residue is provided. As the clay crusher (crusher 30), for example, a roller mill, a toothed roller, a ball mill, a high-speed dissolver (agitator), or the like can be used.

The first classifier 20 is a device for sieving the waste mud to extract waste mud containing fine particles of 2 mm or less, and the clay lumps contained in the waste mud discharged from the shield machine 10 Sieve. Here, waste mud containing fine particles of 2 mm or less is assumed to contain contaminants, and is stored in the sludge dissolution tank 40 in order to separate the contaminants and perform volume reduction treatment. Further, as described above, the sieved residual portion exceeding 2 mm may contain clay lumps, so it is pulverized by the pulverizer 30 and then stored in the desludging tank 40 .

<Thawing tank>
The sieving tank 40 is a storage tank for temporarily storing the sieved residue sieved by the first classifier 20 and the under-sieved material crushed by the crusher 30 . That is, the dissolving tank 40 is a storage tank for temporarily storing the entire amount of the waste mud discharged from the shield machine 10 after disintegrating (dissolving) clay lumps and the like having a size of 2 mm or more. be. Waste mud stored in the desludging tank 40 is delivered to the sand washing tank 80 via the second classifier 50 . Although not shown, the dissolution tank 40 is equipped with a pump for sending the waste mud to the second classifier 50 .

<Gravel classifier>
The gravel classifier is a device for removing gravel exceeding 2 mm from waste muddy water in which clay lumps have been crushed, and is composed of a second classifier 50 . Waste mud is sent to the sand washing tank 80 from the desludging tank 40 via the second classifier 50 . As described above, the second classifier 50 removes gravel exceeding 2 mm contained in the waste mud stored in the desludging tank 40 and sends it to the sand washing tank 80 .

<Sand cleaning classifier>
The sand washing and classifying equipment consists of a group of equipment for washing and classifying the sand contained in the waste muddy water. A group of devices for washing and classifying sand consists of a suction pump 90 for sucking waste mud stored in the sand washing tank 80, and discharging the waste mud sucked by the suction pump 90 together with compressed air at high pressure. It consists of an injection nozzle 100 that collides with the inner wall (plate-shaped member) of the sand washing tank 80 and a third classifying device 60 that includes a cyclone 70 . The suction pump 90 and the injection nozzle 100 are connected to each other by an injection hose. In addition, although not shown, the sand washing tank 80 includes a pump for sending the waste mud to the third classifier 60 including the cyclone 70, and a compressor for accelerating the waste mud sucked by the suction pump 90 at the time of discharge. ing.

In the sand washing tank 80 , waste muddy water containing sand sucked by the suction pump 90 is jetted from the jet nozzle 100 together with compressed air, and collides with the inner wall of the sand washing tank 80 . At this time, the fine particles adhering to the surface of the sand particles are separated from the sand particles, resulting in sand to which contaminants are not adhered. Further, the waste muddy water temporarily stored in the sand washing tank 80 is screened by the cyclone 70 and the third classifier 60 to remove sand particles having a size of 0.075 mm or more and less than 2 mm. The sieved sand is treated as primary treated soil (washed sand). On the other hand, the unsieved material that has passed through the cyclone 70 and the third classifier 60 is returned to the sand washing tank 80 . Then, the waste muddy water that has been added with water and has an appropriate water content is subjected to the above-described treatment repeatedly, thereby removing sand with a size of 0.075 mm or more and less than 2 mm.

<pH adjuster>
The waste mud containing fine particles of less than 0.075 mm classified by the cyclone 70 is temporarily stored in the adjustment tank 120 and then delivered to the waste mud receiving tank 130 . A pH adjuster is added to the waste muddy water receiving tank 130 from the pH adjuster 110 . Further, in the present embodiment, iron powder is added to the waste muddy water by the iron powder adding device 150 . The pH adjuster 110 is a device on the assumption that the iron powder is reused, and adjusts the waste muddy water to about pH 5 in order to prevent the iron powder from dissolving more than necessary.

Experimental results have also been obtained that the removal rate of fluorine is improved by adjusting the pH of the waste muddy water to about 5. For example, after adding iron powder to waste muddy water containing 0.05 mg/L of lead and 4 mg/L of fluorine and stirring for 1 hour, the fluorine removal rate was about 70% at pH 5 and about 60% at pH 5.5. It was about 7% at pH 6. That is, when pH 5 and pH 6 are compared, the fluorine removal rate can be increased about 10 times by setting the pH to 5.

Among the waste mud temporarily stored in the adjustment tank 120, the waste mud containing fine particles of less than 0.075 mm is temporarily stored in the mud feed tank 140, and then drilled in the shield machine 10. reused as Although not shown, the adjusting tank 120, the waste mud receiving tank 130, and the mud feeding tank 140 are provided with pumps for sending out the waste mud to a device disposed in the subsequent stage.

<Iron powder adding device/Iron powder separating device>
The iron powder adding device 150 adds iron powder to the waste mud which has been adjusted in pH and sent to the pollutant adsorption tank 170, so that the iron powder adsorbs pollutants such as fluorine, lead, and arsenic. It is a device. In the contaminant adsorption tank 170, iron powder is added to waste muddy water, and contaminants such as fluorine, lead, and arsenic are adsorbed and removed by the iron powder. Contaminants such as fluorine, lead, and arsenic are removed by the iron powder, and the waste mud from which the iron powder is separated is sent to the purification mud tank 180 . Although not shown, the contaminant adsorption tank 170 is provided with a pump for sending out the waste muddy water to a device arranged in the subsequent stage.

The iron powder separator 160 consists of a cyclone and is a device for gravity separation into waste muddy water containing no iron powder and iron powder to which contaminants such as fluorine, lead and arsenic are adsorbed. The iron powder separated by specific gravity by the iron powder separator (cyclone) 160 is directly fed from the cyclone into the contaminant adsorption tank 170 and reused a predetermined number of times. The waste muddy water sent to the contaminant adsorption tank 170 has already had its sand removed, so it is composed of fine particles and iron powder, which have extremely different specific gravities, and can be easily separated by specific gravities. is.

Therefore, it is possible to simplify the apparatus without using a magnetic separator. That is, in the present invention, it is possible to reduce costs and equipment troubles. Japanese Patent Application No. 2016-35087 (Japanese Patent Application Laid-Open No. 2017-148760) already filed by the applicant of the present application includes a magnetic separation device for recovering iron powder. Since it is removed, the magnetic separator can be omitted.

Since iron powder separated from waste muddy water adsorbs contaminants such as fluorine, lead, and arsenic, it is treated with acid, alkali, ascorbic acid, or a combination thereof after being reused a predetermined number of times. This allows the contaminants to be separated and the adsorption capacity of the contaminants to be restored. Separated contaminants such as fluorine, lead, and arsenic should be disposed of appropriately.

<Iron powder>
The iron powder used in the apparatus for reducing the volume of waste muddy water of the present invention is a porous iron powder and a surface-oxidized iron powder obtained by surface-oxidizing the porous iron powder. An experimental result has been obtained that the surface-oxidized iron powder can increase the fluorine adsorption rate as compared with the iron powder not subjected to the surface-oxidized treatment. For example, the fluorine removal rate in waste muddy water containing 0.05 mg/L of lead and 4 mg/L of fluorine is about 7% for porous iron powder whose surface is not oxidized, and about 60% for surface-oxidized iron powder. there were. When the surface-oxidized iron powder and the porous iron powder are used together, they are blended at a ratio of 1:1. The amount of iron powder added to waste mud is about 2 to 16%. Therefore, when the contaminants in the waste mud contain fluorine, the iron powder adding device 150 preferably adds iron powder whose surface has been oxidized. When arsenic is contained, it is preferable to add iron powder whose surface has been oxidized and porous iron powder.

Part or all of these iron powders have a large number of fine pores extending from the surface to the inside, and have a particle size of 150 μm or more and 300 μm or less and an apparent density of 1.3 g/cm ³ or more and 1.5 g/cm ³ or less. , a specific surface area of 0.12 m ² /g or more and 0.36 m ² /g or less. In addition, it is desirable that iron powder having a particle size of 150 μm or more accounts for 90%. Also, the apparent density can be 1.3 g/cm ³ or more and 2.0 g/cm ³ or less. The value of the specific surface area is measured according to JIS Z 8830:2013 by the BET multipoint method/adsorption side relative pressure (P/P ₀ =0.001 to 0.30). The critical significance of such properties of the iron powder will be explained.

<Particle size of iron powder>
If the particle size of the iron powder is less than 150 μm, there is a risk that the muddy water and the iron powder cannot be reliably separated when performing specific gravity separation. On the other hand, when the particle size of the iron powder exceeds 300 μm, the dispersibility of the iron powder in the muddy water to be treated decreases during the process of adsorbing heavy metals to the iron powder, and the adsorption efficiency of heavy metals decreases.

<Apparent density of iron powder>
If the iron powder has an apparent density of less than 1.3 g/cm ³ , the number of micropores increases and the strength of the iron powder decreases. If there is no strength problem, the apparent density of the iron powder can be allowed up to 1.0 g/cm ³ . On the other hand, when the iron powder has an apparent density of more than 1.5 g/cm ³ , the number of micropores is reduced and the heavy metal adsorption efficiency is reduced.

<Specific surface area of iron powder>
If the specific surface area of the iron powder is outside the range of 0.12 m ² /g or more and 0.36 m ² /g or less, heavy metals cannot be efficiently adsorbed, and the amount of heavy metals that can be removed decreases.

<Porous iron powder/surface-oxidized iron powder>
The iron powder used in the present embodiment has a property of having a large number of fine pores extending from the surface to the inside, that is, by making the iron powder porous (sponge-like), the surface area of the iron powder itself increases, and heavy metals Adsorption efficiency is improved. In addition, as described above, by subjecting the surface to an oxidation treatment, the adsorption of fluorine can be enhanced.

<Purifying mud tank>
The purified mud tank 180 is a storage tank for storing the waste mud purified by removing contaminants such as fluorine, lead, and arsenic in the pollutant adsorption tank 170, adjusting the pH, and adding a coagulant. be. In the clarified mud tank 180, a pH adjuster and a flocculating agent are added to the waste mud, and then the waste mud is sent to a dehydration treatment device (filter press 190). Although not shown, the clarified mud water tank 180 is provided with a pump for sending waste muddy water (purified muddy water) to a device disposed in the subsequent stage.

<Dehydration equipment>
The dewatering device (filter press 190) is a device for dewatering waste mud (purified mud) sent from the purified mud tank 180. FIG. That is, the amount of waste mud can be reduced by dehydrating the mud from which all the iron powder has been collected by the dewatering device (filter press 190). The device for dehydration is not limited to the filter press 190, and a vacuum pressurized dehydrator or the like can be used. By using a vacuum pressurized dehydrator that performs dehydration by adding cement as a dehydration device, a self-hardening dehydrated cake is produced, further reducing the risk of elution of contaminants (hazardous substances) in the future. can be reduced. The filtered water discharged from the dewatering device (filter press 190 ) is temporarily stored in the mud feeding tank 140 and then reused as drilling mud in the shield machine 10 .

<Method for reducing volume of waste muddy water>
The method for reducing the volume of waste muddy water according to the embodiment of the present invention reduces the volume of waste muddy water containing contaminants such as fluorine, lead, arsenic, etc., using the above-described waste muddy water volume-reducing equipment. process. That is, as shown in FIG. 2, the method for reducing the volume of waste mud according to the embodiment of the present invention includes a clay crushing step (S1 ), sand cleaning and classification step (S2), pH adjustment step (S3), iron powder addition step (S4), iron powder adsorption and classification step (S5), and dehydration treatment step (S6). The specific numerical values (treatment time, treatment temperature, pH, etc.) in each process are as described in the waste muddy water volume reduction treatment apparatus.

Specifically, the clay clumps contained in the waste mud are crushed (S1), the sand is washed away from the waste mud in which the clay clumps are crushed (S2), and the sand is removed from the waste mud. Adjust the pH (S3). Subsequently, iron powder is added to the pH-adjusted waste mud (S4). Subsequently, after the contaminants are adsorbed on the iron powder, a cyclone is used to separate the waste muddy water containing no iron powder from the iron powder to which the contaminants are adsorbed (S5). In order to cause the iron powder to adsorb the contaminants, the waste mud to which the iron powder has been added is agitated at a prescribed temperature for a prescribed time. At this time, when fluorine is contained as a contaminant, porous iron powder having an oxidized surface is added to improve the ability to remove fluorine.

The iron powder that has been gravity-separated is directly added for a predetermined number of times. The iron powder that has been reused a predetermined number of times is treated with acid, alkali, ascorbic acid, or a combination of these to separate contaminants and restore the ability to adsorb contaminants, followed by the iron powder addition step ( In S4), it is recycled.

Subsequently, the waste muddy water from which the iron powder has been separated is dehydrated (S6). The filtered water discharged from the dehydrator (for example, the filter press 190) is reused as drilling mud in the shield machine 10.

<Advantageous effects of the present invention compared with the prior art>
Hereinafter, it will be explained that the volume reduction treatment apparatus and the volume reduction treatment method for waste muddy water according to the present invention exhibit advantageous effects as compared with conventionally conceived apparatuses and methods. It is difficult to recover iron powder from waste mud exceeding about 700 m ³ with the conventional device configuration for pumping up iron powder-mixed waste mud water from the iron powder mixing tank to the magnetic separator and recovering clarified mud water. This is because, in the method of pumping up the waste mud water containing iron powder from the iron powder mixing tank to the magnetic separator and recovering the clarified mud water, it is necessary to process the waste mud water exceeding about 700 m ³ within 2 to 3 hours. Therefore, a processing capacity of about 230 to 350 m ³ /h is required, and a plurality of processing units (for example, 5 to 8 units) are required.

In addition, in the method of supplying the muddy water to be treated from the lower side of the rotating drum in a magnetic separation apparatus such as a drum type, when muddy water containing a large amount of sand is treated, the water channel under the rotating drum is clogged with earth and sand. Since there is a risk of causing defects, there is concern about making it a treatment facility suitable for the site. In this respect, in the waste muddy water volume reduction processing apparatus and volume reduction processing method according to the present invention, since sand is removed from the waste muddy water in advance, there is no need to use a magnetic separation device such as a drum type. Such a problem does not occur.

10 shield machine 20 first classifier 30 crusher 40 desludging tank 50 second classifier 60 third classifier 70 cyclone 80 sand washing tank 90 suction pump 100 injection nozzle 110 pH adjuster 120 adjustment tank 130 waste muddy water Receiving tank 140 Sludge tank 150 Iron powder adding device 160 Iron powder separating device (cyclone)
170 pollutant adsorption tank 180 purified mud tank 190 dehydration treatment device (filter press)

Claims (4)

A device for reducing the volume of waste muddy water mixed with contaminants containing at least fluorine, lead, and arsenic,
a clay crushing device for crushing clay lumps contained in the waste muddy water;
a sand cleaning and classifying device for cleaning and removing sand contained in waste mud from which clay lumps have been crushed;
a pH adjusting device that adjusts the waste muddy water from which sand has been removed to pH 5 to 5.5 ;
an iron powder addition device for adding porous iron powder and iron powder subjected to surface oxidation treatment to pH-adjusted waste mud at a ratio of 1:1;
An iron powder separator that uses a cyclone to separate waste muddy water containing no iron powder and iron powder with adsorbed contaminants by specific gravity;
a dewatering device for dewatering the waste muddy water after the iron powder has been separated;
A volume reduction treatment device for waste muddy water, comprising: The sand washing and classifying device is a device that sucks waste muddy water from which clay lumps have been crushed, discharges it at high pressure together with compressed air, and makes it collide with a plate-shaped member to separate fine particles adhering to sand. 2. The apparatus for reducing the volume of waste muddy water according to claim 1 , comprising: A method for reducing the volume of waste muddy water containing contaminants containing at least fluorine, lead, and arsenic, comprising:
a clay crushing step of crushing clay lumps contained in the waste muddy water;
A sand cleaning and classification process for cleaning and removing sand contained in waste mud in which clay lumps have been crushed;
A pH adjustment step of adjusting the waste muddy water from which sand has been removed to pH 5 to 5.5 ;
an iron powder addition step of adding porous iron powder and iron powder subjected to surface oxidation treatment to pH-adjusted waste mud at a ratio of 1:1;
An iron powder adsorption classification step of adsorbing contaminants to iron powder and using a cyclone to separate waste muddy water containing no iron powder and iron powder with adsorbed contaminants by specific gravity;
A dehydration process for dehydrating the waste muddy water after the iron powder has been separated;
A method for reducing the volume of waste muddy water, comprising: In the sand washing and classifying step, the waste muddy water in which clay lumps have been crushed is sucked and discharged at high pressure together with compressed air, and is caused to collide with a plate-shaped member, thereby peeling off the fine particles adhering to the sand. The method for reducing the volume of waste muddy water according to claim 3 .

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