JP2004276019A - Treatment method for contaminated water, contaminated mud, and other contaminated object to be treated - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method for a contaminated object to be treated capable of treating contaminated water and mud, or the like, containing hazardous substances such as DXNS (dioxins) and heavy metals by relatively simple treatment facilities and processes at low costs, and obtaining filtered water under the emission regulations by surely capturing the hazardous substances to suppress the elution by enclosing the water in a dehydrated cake. <P>SOLUTION: The treatment method is for treating the contaminated water containing DXNS, or the like, generated in cleaning work at demolition work, or the like, in a waste incineration facility, the contaminated mud containing DXNS, or the like, of dredged spoil, or the like, of dredged bottom sediment of harbors, and the heavy metals contaminated soil (B mud slurry). Stone dust for capturing DXNS, or the like, and A mud slurry A<SB>S</SB>wherein an adsorbent is added to mud materials such as bentonite are placed in a filtration chamber such as a filter press 8. B mud slurry B<SB>S</SB>comprising the contaminated water is placed in the A mud slurry A<SB>S</SB>. The B mud slurry is dehydrated using the A mud layer as a filter and a desorption layer, and is subjected to solid/liquid separation to obtain the dehydrated cake C and filtrated water W. The DXNS and heavy metals, or the like, are enclosed inside the dehydrated cake (A mud and B mud) by capturing, desorbing, insolubilizing, or the like. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for treating an object to be contaminated, which contains harmful substances such as dioxins (hereinafter referred to as DXNs). For example, the present invention relates to a method for treating DXNs generated during a cleaning operation when dismantling a waste incineration facility. Treatment of contaminated water containing water, or addition to DXNs and heavy metals containing sediment deposited in harbors, lakes and marshes or soil containing DXNs and heavy metals to form a slurry, then classify and remove coarse particles After that, it is effectively applied to the treatment of contaminated mud containing a large amount of fine particles and DXNs and heavy metals.

  With the enforcement of the Act on Special Measures against DXNs, the need for dismantling old (incompatible with new emission standards) waste incineration facilities is increasing. The waste incineration facility is composed of an incinerator body, flue equipment, dust removal equipment, flue gas cooling equipment, smoke washing equipment, wastewater treatment equipment, waste heat boilers, and the like. Toxins such as DXNs are present as furnace wall deposits, incineration ash, and fly ash around these, especially inside, and DXNs are scattered in and around the workplace with the dismantling of these facilities. there is a possibility. For this reason, in the demolition of incineration facilities, prior to demolition, a method is adopted in which the entire workplace is covered and hermetically sealed, and debris on the furnace wall, incineration ash and fly ash are washed out to prevent diffusion.

  As a general cleaning method, a method of cleaning the inside of the facility with high-pressure jet water is adopted.For incinerator bodies, flue equipment, dust removal equipment, etc., workers wearing protective equipment perform cleaning with a cleaning nozzle. Do. The inside of the chimney with a height difference is cleaned by a method in which a special high-pressure injection device is suspended by a crane or the like.

  The existing treatment technologies for such contaminated water are roughly classified into the following two.

  (1) A method in which the generated contaminated water is collected in a muddy state in a tank car, etc., then carried out, and the muddy water is incinerated as it is in a treatment facility that complies with the new emission standards.

  (2) A method of installing a treatment facility in the demolition site of an incinerator and performing an intermediate treatment. As this treatment method, advanced treatments such as coagulation sedimentation, sand filtration, membrane separation, adsorption, and chemical treatment are generally performed. Basically, solid-liquid separation is performed, the supernatant water is reused as washing water, and the precipitate is subjected to a dehydration treatment using a filter press or the like. In this case, the filtrate contains soluble DXNs and the SS (Suspended Solid: suspended solids) contains DXNs. Chemical treatment is performed, and the water is released at the emission standard (10 pg-TEQ / L) or less. The reduced volume of the dewatered cake will be melted or fired at treatment facilities that comply with the new emission standards.

  Under the DXN Measures Special Measures Law, the sediment DXN content is set at an environmental standard of 150 pg-TEQ / g, and it is required that port sediment exceeding this standard be promptly addressed. Measures include excavating and removing contaminated sediment, covering sand, and solidifying in situ. In the excavation and removal process, after the contaminated sediment is dredged and reduced in volume, the detoxification process, landfill, and insolubilization process are performed according to the concentration of DXNs. Selected. In general, the volume of the dredged sediment is reduced by dewatering with a filter press after removing coarse particles.

  In this case, the DXNs and most of the harmful heavy metals are often adsorbed to the fine particles of the mud, the DXNs and the heavy metals are concentrated in the SS in the filtrate, and the soluble DXNs and the heavy metals are contained. Since it may be present, advanced treatments such as coagulation sedimentation, sand filtration, membrane separation, adsorption, and chemical treatment are required as post-treatments of the drainage.

In addition, as a prior art related to the present invention, the present applicant has filed an application for a dehydration and solidification method of a highly water-containing slurry (see Patent Document 1). The present invention is a method for efficiently dehydrating hard-to-dehydrate high-water-content slurry such as dredged bottom mud and construction sludge, and enabling effective use of a dewatered cake. Then, a specific treatment material A is added to one of the slurries to prepare a slurry A, and another specific treatment material B is added to the other slurry to prepare a slurry B. First, A slurry is applied to a filter press or the like. This is a so-called mud wrap method in which mud slurry is cast and dewatered, and then mud slurry B is cast and dewatered through a precoat layer of mud cake A.
JP 2000-24694A

  However, the conventional method (1) has a drawback that a large amount of sludge water is carried out and disposed, so that the cost of carrying out and disposal is high. In addition, although the method (2) reduces the volume, it uses a combination of multiple processing technologies and requires many processing equipment and processes, which makes equipment and on-site maintenance complicated, and There is a disadvantage that processing cost is high.

  In addition, the current series of processes for dewatering contaminated mud, insolubilizing dewatered cake, and purifying drainage is also a combination of multiple processing technologies, and requires many processing facilities and processes. There is a disadvantage that maintenance and the like become complicated and processing costs are high.

  The present invention has been made to solve the above-described problems, and can treat contaminated water or mud containing harmful substances such as DXNs and heavy metals with relatively simple treatment equipment and treatment steps. Provided is a method for treating a contaminated material which can be carried out at low cost, and can reliably capture and confine harmful substances such as DXNs and heavy metals in a dewatered cake, and can also obtain drainage below discharge standards. It is in.

  Claim 1 of the present invention is a method for treating a pollutant to be treated (contaminated water such as washing contaminated water, contaminated mud such as dredged soil, or contaminated soil) containing harmful substances (DXNs, heavy metals, etc.). A mud slurry composed of a mud material that captures harmful substances is cast into a dehydration treatment chamber, and a B mud slurry composed of a pollutant to be treated containing a harmful substance is cast into the A mud slurry. Then, the slurry of mud B is dewatered using the mud layer A as a precoat layer, solid-liquid separated into dewatered cake (mud A and mud B) and filtrate, and harmful substances are surely captured in the dewatered cake. This is a method for treating an object to be contaminated, characterized in that the treatment is performed below the emission standard.

  The feature of the present invention is that DXNs are hardly soluble in water, and the fact that most of them are derived from SS (floating suspended solids). The precoat layer (A mud layer: conventional Unlike contaminated water and contaminated mud, the SS component in contaminated water and contaminated mud (B mud) containing DXNs and heavy metals is captured in the dewatered cake. The soluble DXNs are adsorbed by the adsorbent, and the drainage water is discharged at a discharge standard or lower. The dewatered cake whose volume has been reduced is subjected to appropriate final disposal such as detoxification treatment or landfill disposal according to the concentration of contamination at treatment facilities that comply with the new emission standards.

  In the case of treatment of contaminated water, A mud slurry composed of mud material that captures harmful substances (DXNs, heavy metals, etc.) is poured into a dehydration treatment chamber, and B mud composed of contaminated water containing harmful substances. The slurry is poured into the A mud slurry, and then the B mud slurry is dewatered using the A mud layer as a pre-coat layer, and solid-liquid separated into dewatered cakes (A mud and B mud) and drainage water. Ensure that harmful substances are trapped and that the drainage is treated below emission standards. That is, for example, this is a technology in which a treatment facility is installed in the demolition site of an incineration facility to carry out intermediate treatment of contaminated water, and contamination including DXNs generated in washing work or other facilities at the time of demolition of a waste incineration facility. It is a treatment of water (B mud slurry), dewaters B mud slurry using mud layer A composed of mud material as a filter and an adsorbing layer, and captures and adsorbs DXNs etc. in dewatered cake (A mud and B mud), It is sealed by insolubilization.

  In the case of treatment of contaminated mud such as dredged soil, A mud slurry composed of mud material that captures harmful substances (DXNs, heavy metals, etc.) is poured into a dehydration treatment chamber and is composed of contaminated mud containing harmful substances. The B mud slurry is poured into the A mud slurry, then the B mud slurry is dewatered using the A mud layer as a precoat layer, and solid-liquid separated into a dewatered cake (A mud and B mud) and filtrate. Hazardous substances are reliably captured in the dewatered cake, and harmful substances in the drainage water are processed to various emission standards or less. That is, it is a treatment of contaminated mud (B mud slurry) such as slurry containing fine particles containing DXNs and heavy metals after sediment and contaminated soil classification washing. The B mud slurry is dehydrated as an adsorption layer, and DXNs and the like are trapped in the dewatered cake, and sealed by adsorption, insolubilization, and the like.

  According to a second aspect of the present invention, in the treatment method according to the first aspect, the mud material of the A mud slurry is a non-aqueous material in which a particle group having a particle size of 75 μm or more is 10% by mass or less and an average particle size is 20 μm or less. This is a method for treating an object to be contaminated, wherein the object is made of conductive inorganic particles. In the case of treating contaminated water, non-water-soluble inorganic particles having a particle size of 75 μm or more in an amount of 10% by mass or less and an average particle size of 10 μm or less are preferred. In the case of treatment of contaminated mud, the average particle size is set to 20 μm or less to ensure efficient dewatering and cake removability.

  According to a third aspect of the present invention, in the treatment method according to the second aspect, when the water-insoluble inorganic particles are treated with contaminated water, one or more of stone powder (calcium carbonate, silica stone powder, etc.) or bentonite is used. And a method of treating contaminated mud, characterized in that in the case of treating contaminated mud, the mud is composed of a mixture of one or more of clay, stone powder and coal ash. is there. That is, in the case of treatment of contaminated water, since the A mud is a filter and an adsorption layer for capturing DXNs and the like, water-insoluble inorganic particles having a particle size appropriate for capturing the DXNs and the like, for example, Use artificial or externally supplied mud such as stone powder or bentonite. Also in the case of treating polluted mud, since the mud A is a filter and an adsorption layer for trapping DXNs and heavy metals, use non-water-soluble inorganic particles suitable for trapping these harmful substances and the like. .

  According to a fourth aspect of the present invention, in the treatment method according to any one of the first to third aspects, in the case of treating contaminated water in the A mud slurry, an inorganic coagulant (PAC, sulfate band, slaked lime, One or more of an organic coagulant (such as polyacrylamide) and an adsorbent (such as activated carbon and zeolite) are added. When treating contaminated mud, an inorganic coagulant and / or Alternatively, one or two or more of the adsorbents are added. That is, in the case of treatment of contaminated water, taking into consideration that soluble DXNs and the like are present in the B mud slurry, activated carbon or zeolite based on PAC (polyaluminum chloride) or slaked lime is used as the A mud treating agent. It is preferable to add an adsorbent such as A to the slurry A mud. In the case of treating contaminated mud, harmful substances are more reliably captured in consideration of the fact that mud slurry A itself does not cause excessive resistance to dewatering of mud B, and the presence of soluble DXNs in mud slurry B. It is a means to do.

  According to a fifth aspect of the present invention, in the treatment method according to any one of the first to fourth aspects, clay or stone powder (calcium carbonate, silica stone powder, or the like) is used for the B mud slurry in the case of treating contaminated water. A method for treating a contaminated object, characterized in that at least one of the following is added. That is, in the case of the treatment of the contaminated water, since the concentration of the B mud slurry changes, mud such as clay or stone powder is added as necessary.

  According to a sixth aspect of the present invention, in the treatment method according to any one of the first to fifth aspects, an inorganic coagulant (PAC, sulfate band, slaked lime, , A polyiron sulphate), an organic coagulant (such as polyacrylamide), or one or more of coagulating and solidifying materials such as cement and lime. This is a method for treating an object to be contaminated, wherein one or more of a lime-based material, a magnesia-based material and the like are added. That is, in the case of treatment of contaminated water, in order to insolubilize DXNs and the like trapped in the dewatered cake, the B mud slurry contains an inorganic or organic coagulant or a coagulating / solidifying material such as cement or lime. May be added. In the case of treating the contaminated mud, the B mud slurry is added with an inorganic coagulating / solidifying material in order to insolubilize (aggregate / contain) DXNs and the like trapped in the dewatered cake.

  A seventh aspect of the present invention is a method for treating an object to be contaminated, wherein a filter press is used for the dehydration treatment in the treatment method according to any one of the first to sixth aspects. That is, in the dehydration treatment, it is preferable to perform pressure dehydration using, for example, a filter press having a large number of filtration chambers. The present invention is not limited to this, and other dehydration processing devices may be used.

  An eighth aspect of the present invention is characterized in that, in the treatment method according to any one of the first to seventh aspects, a part of the beginning of the mud filtrate discharged in the dehydration treatment is recovered in the B mud slurry. This is a method for treating a contaminated object to be treated. That is, when the driving pipes to the dehydration processing apparatus such as a filter press share both the A mud and the B mud, the residual B mud in the previous process pipe and the next process A mud are mixed at the start of the next step driving, and the A mud is discharged. Since DXNs and the like are mixed in the filtrate, a part of the slurry A, which has started to be discharged, is collected in slurry B.

  According to a ninth aspect of the present invention, in the treatment method according to any one of the first to eighth aspects, in the case of treating contaminated water, the contaminated water obtained by washing the facility is separated into a solid and a liquid, and the supernatant is obtained. This is a method for treating an object to be contaminated, wherein water is reused as washing water, and a sediment is supplied as a B mud slurry to the next step. That is, this is the case of contaminated water (B mud slurry) generated during the cleaning operation when the waste incineration facility is dismantled. In order to suppress the final treatment amount of the contaminated water, the collected contaminated water is separated into solid and liquid in a storage tank or the like. The supernatant water is reused as washing water.

  According to the present invention as described above, using a mud wrapping method using a filter press or the like, dehydrating a B mud slurry such as contaminated water or contaminated mud as an A mud layer composed of mud material as a precoat layer, DXNs are trapped in dewatered cakes (mud A and mud B) and trapped by adsorption, insolubilization, etc., so that treatment of contaminated water or mud containing harmful substances such as DXNs and heavy metals is relatively difficult. It can be carried out at low cost with simple processing equipment and processing steps, and it is possible to reliably capture harmful substances such as DXNs and to obtain drainage below discharge standards.

  According to a tenth aspect of the present invention, in the processing method according to any one of the first to ninth aspects, a plurality of filtration chambers are arranged in a pressing direction for dehydrating the A mud slurry and the B mud slurry. A filter press is used to supply air pressure from the outside to a continuous driving channel formed in the pressing direction formed from the driving ports of the plurality of filter chambers to remove first the residual B mud at the driving port. A pollution treatment characterized by performing a secondary removal by passing a scraper having a shape capable of closing the cross section of the driving passage into the driving flow path, and then performing a tertiary removal by passing fresh water through the driving flow path. It is a method of processing objects.

  The tenth aspect is a case where a filter press is used in a dehydration treatment apparatus in a method for treating contaminated water for cleaning or contaminated mud (the inventions of the first to ninth aspects). The general procedure for using this filter press is as follows: A mud driving → B mud driving / pressure dewatering → open frame (dehydration cake removal) → closed frame →→→ A mud driving → B mud driving / pressure dewatering → Open frame (take out dehydrated cake) → Close frame → → → The same cycle is repeated. In addition, the B mud slurry composed of contaminated water and the like is used as a filter and an adsorbent layer for the A mud layer to be dewatered, solid-liquid separated into dewatered cake and filtrate, and DXNs and the like in the dewatered cake (A mud and B mud). Harmful substances are trapped, adsorbed, and insolubilized (solidified).

  As shown in the roles and procedures of the above-mentioned mud A and mud B, if the mud B composed of clean A mud and harmful polluted water, which is a filter layer, is mixed in the treatment process and the like, naturally, the treatment of the present invention is performed. The meaning of the technology has become smaller, while the A mud and B mud are alternately driven. In order to prevent mixing of mud A and mud B, it is ideal to completely separate the mud and mud storage / mixing tank, driving pump and piping system separately from each other in terms of equipment.

  However, even in this case, the driving port in the filter press following the driving pipe is naturally one system due to its structure. The next step A mud is mixed with the mud. Therefore, B mud remaining in the insertion port of the filter press was removed and washed before the A mud implantation in the next step.

  By performing primary removal by air pressure, secondary removal by a plunger or the like (several times if necessary), and tertiary removal by clear water, B mud remaining in the insertion port of the filter press is removed before A mud implantation in the next process Thus, it is possible to completely prevent the mixing of the mud of the previous step B with the mud of the next step A.

  According to a eleventh aspect of the present invention, in the treatment method according to any one of the first to tenth aspects, the treatment method is provided at a discharge port of a filter chamber of a filter press for performing a dewatering treatment of the A mud slurry and the B mud slurry. A method for treating an object to be treated for contamination, characterized in that an auxiliary filter cloth which is continuous with the filter cloth is provided on a surface of a fixing member of the filter cloth (a flange-shaped filter cloth fixing plate).

  The eleventh aspect is also a case where a filter press is used in a dehydration treatment apparatus in a method for treating contaminated water for washing or contaminated mud (the inventions of the first to tenth aspects). The basic mechanism of dewatering of a general-purpose filter press is that, by injecting pressure mud, only the water in the mud (strictly speaking, the ultrafine soil smaller than the filter cloth passes) passes through the filter cloth and the soil larger than the filter cloth The particles remain inside the filter cloth, whereby solid-liquid separation can be achieved. On the other hand, from many of the past examples of filter press dewatering, it has been confirmed that although the dewatering cake as a whole can be dewatered as required, the dewatering state near the center of the cake is not sufficient and is in a semi-solid state.

  This factor can be inferred from the basic mechanism and the filter plate structure described above. (1) A flange-shaped filter cloth fixing plate for fixing the filter cloth is present around the insertion hole at the center of the filter plate. (2) The filter cloth fixing plate is made of, for example, bakelite and is made of a material and structure that does not allow moisture to pass therethrough. (3) Therefore, the dehydration state is remarkably inferior in the vicinity of the cake center compared with other parts. (4) Furthermore, in the case of the diorap method, it is also assumed that the B mud layer is completely wrapped with the A mud layer so that the B mud does not directly contact the filter cloth. DXNs and the like are extremely likely to be mixed into the drainage water), but in places where water does not pass through on the center side of the flange diameter, it is impossible to form a mud layer because water does not pass through. is there. Conversely, on the filter cloth surface through which moisture permeates, formation of the mud layer A is reliable.

  Focusing on these, the dehydration of the water in the muddy water located at the center from the flange diameter can be promoted, and the formation of the A mud layer can be surely performed. That is, an auxiliary filter cloth was stuck on a flange-shaped filter cloth fixing plate in order to ensure water permeability up to the nearest part of the insertion port. According to this method, (1) a uniform dehydrated cake including the central portion of the dehydrated cake was formed. (2) A mud layer could be formed right near the injection port.

  According to a twelfth aspect of the present invention, in the treatment method according to any one of the first to eleventh aspects, harmful substances in the filtrate of the B mud slurry are decomposed by a photocatalyst, the solid content is separated by filtration, and the filtrate is filtered. This is a method for treating an object to be contaminated, characterized in that the treatment is performed below a wastewater standard.

  According to a thirteenth aspect of the present invention, in the treatment method according to the twelfth aspect, the decomposition of the harmful substance is performed by an oxide phase mainly composed of a silica component (a first phase) and a metal oxide phase other than silica (a second phase). ), Comprising a woven fabric of a silica-based conjugate fiber having a photocatalytic function in which the content of at least one component of the second phase is inclinedly increased toward the surface layer of the fiber. The present invention is a method for treating an object to be contaminated, which is performed by a purifying apparatus including a filter and an ultraviolet lamp.

  The inventions of Claims 12 and 13 are applied to a method for treating contaminated washing water or contaminated mud (the inventions of Claims 1 to 11). DXNs that are hardly dissolved in water and adhere to solids And a dehydration step of adsorbing DXNs and the like dissolved in water such as washing water, and a step of decomposing soluble DXNs and the like in the filtrate after this step with photocatalytic fibers.

  First, in the dewatering step, the solid content in the contaminated water (mud B) containing DXNs and the like is captured as a dewatered cake using the pre-coat layer (mud layer A) which is a feature of the mud wrap method, and is soluble in the pre-coat layer. Most of the DXNs are adsorbed (the dehydration step of the invention of claims 1 to 11). Next, soluble DXNs and the like in the filtrate discharged in the dehydration step are decomposed by a highly functional photocatalyst.

  The high-performance photocatalytic decomposition is a fiber comprising a composite oxide phase of an oxide phase mainly composed of a silica component (first phase) and a metal oxide phase other than silica (second phase, titanium oxide, etc.). A filter made of a woven fabric of silica-based composite oxide fibers having a photocatalytic function, wherein the proportion of at least one component of the second phase is inclinedly increased toward the surface layer of the fibers; (See JP-A-2003-10612).

  Conventionally, fine solids to which DXNs are adhered are taken into the dewatered drainage water, and the reduction of DXNs becomes insufficient. ), And the decomposition rate was reduced, resulting in a reduction in the throughput. Further, there is a problem that the load balance between the solid-liquid separation step by dehydration and the separation / decomposition step of DXNs becomes unbalanced, and there is a drawback that the step management becomes complicated and the processing cost increases.

  In the high-performance photocatalytic decomposition of the present invention, titanium oxide is less likely to fall off than a conventional glass filter having a titanium oxide coating on the surface, and high decomposition efficiency is obtained because titanium is concentrated on the filter surface. It has the following characteristics. Furthermore, since the solid content in water such as washing water or the content or ratio of insoluble or soluble components such as DXNs fluctuate greatly depending on dismantling properties, etc., the conventional method involves solid-liquid separation and DXNs. Although the processing capacity balance of the decomposition of liquor tends to be unbalanced, the present invention is excellent in the function of separating and decomposing DXNs and the like in the dehydration and subsequent drainage treatment steps, so that load adjustment is easy and efficient. Become.

  The present invention utilizes a mud wrap method using a filter press or the like, and dewaters a B mud slurry such as contaminated water or contaminated mud by using a mud layer A composed of mud material as a pre-coat layer to form a dewatered cake (A mud and DXNs, heavy metals, and the like are trapped, adsorbed, insolubilized, and the like in the mud B), and the following effects are obtained.

  (1) The treatment of contaminated water or muddy water containing harmful substances such as DXNs and heavy metals can be performed at a low cost with relatively simple treatment equipment and treatment steps. This is extremely advantageous in terms of on-site maintenance and cost as compared with the related art.

  (2) Harmful substances such as DXNs and heavy metals can be reliably captured, and drainage below discharge standards can be obtained.

  Further, according to the present invention, the following effects can be obtained by removing and washing the residual B mud in the driving hole in the filter press and providing the auxiliary filter cloth on the filter cloth fixing plate.

  (1) It is possible to completely remove the residual B mud in the injection port, without mixing B mud into the A mud layer, and by using a clean A mud layer which is a filter layer, DXNs etc. can be surely formed into a dewatered cake. It is possible to reliably obtain contaminated and drained water below the discharge standard.

  (2) The auxiliary filter cloth can form a uniform dewatered cake without a semi-solidified / semi-liquefied state including the central part of the dewatered cake, and can form the A mud layer right near the injection port. As a result, a clean A mud layer is formed in the entire filtering chamber, so that DXNs and the like can be reliably contained in the dewatered cake, and drainage below the discharge standard can be reliably obtained.

  (3) The general-purpose filter press can be used almost as it is without major modification, and the processing technology of the present invention can be implemented with low-cost processing equipment.

  Further, in the present invention, the soluble DXNs and the like in the drainage water after the dehydration step in the treatment method for the cleaning contaminated water and the contaminated mud are decomposed by a purifying device made of photocatalytic fibers and the like, and the solid content is filtered off. This produces the following effects.

  (1) The drainage water after the dehydration step can be reliably discharged to a level below the discharge standard for DXNs and the like.

  (2) By using high-functional photocatalytic decomposition, higher decomposition efficiency than before can be obtained, and it is possible to reliably reduce DXNs and the like in the filtrate and increase the throughput.

  (3) In addition, because of its excellent function of separating and decomposing DXNs and the like in the drainage treatment process, load adjustment is easy and efficient treatment is possible.

  Hereinafter, the present invention will be described based on the illustrated embodiments.

[First Embodiment]
The first embodiment is an example in which the present invention is applied to the treatment of contaminated water containing DXNs, heavy metals, and the like generated in a cleaning operation when dismantling a waste incineration facility. FIG. 1 is a schematic diagram of an equipment flow showing an example of a processing equipment of a first embodiment for carrying out a basic processing method of the present invention. FIG. 2 is a sectional view showing the processing steps in the filter press of the present invention in the order of steps.

In the embodiment of FIG. 1, the treatment equipment according to the present invention is installed in a demolition site of an incineration facility, and converts polluted water W ₀ containing DXNs and the like generated by washing with the washing nozzle 1 into a mud by a filter press. Rapid dewatering and volume reduction and solidification using the wrapping method, DXNs and the like are confined in the dewatered cake C, the dewatered cake C is incinerated, etc., and the drainage water W is discharged to a discharge standard or less. Mainly in order from the upstream side, the contaminated water collecting pit 2, the gravel / sand separation device 3, the supernatant water tank 4, the storage tank 5, the A mud mixing tank 6, the B mud mixing tank 7, the filter press 8, the filtration tank 9, It comprises a neutralization tank 10 and a water discharge monitoring tank 11. The details of the processing steps are as follows (see FIG. 1).

(1) Contaminated water W ₀ after cleaning by high-pressure injection of the cleaning nozzle 1 is collected in the contaminated water collecting pit 2, and after removing the gravel sand by the gravel / sand separation device 3, the storage tank is transferred by the transfer pump 20. 5 and the supernatant water is separated while being stirred by the stirrer 21. Here, in order to suppress the final treatment amount of the contaminated water, the supernatant water W ₁ of the storage tank 5 is sent to the supernatant water tank 4, and the supernatant water W ₁ is supplied to the cleaning nozzle 1 by the high-pressure injector 22 to collect and recycle. Use.

(2) Settling sludge water W ₂ (incinerated ash, residue (sand remaining in the facility, rust, refractory brick in the furnace, etc.)) containing DXNs etc. in the storage tank 5 is mixed with the B mud by the transfer pump 23 The slurry is sent to the tank 7 to produce a B mud slurry B _S. If necessary, a processing material B described later from the melting tank 14 or a mud material D described later from the mud making tank 12 is added. On the other hand, the A mud mixing tank 6, sends a mud material D to be described later from Sakudoroso 12, with the addition of treatment materials A to be described later from the dissolution tank 13, to produce the A mud slurry A _S.

(3) First, the mud slurry A _S is driven into the filter chamber in the filter press 8 by the driving pump 24, and then the piping is switched to drive the mud slurry B _S. As shown in FIG. 2, when the B mud slurry B _S is poured into the A mud slurry A _S placed in the filtration chamber 8a, the dehydration of the A mud slurry A _S proceeds, and the A A precoat layer is formed by the mud, dehydration of the B mud proceeds through the precoat layer and the filter cloth, and solid-liquid separation into a dewatered cake C (A mud and B mud) and filtered water W. After the completion of the dehydration, the mold is opened and the dehydrated cake C is taken out.

  Here, in the contaminated water generated in the washing operation at the time of dismantling the waste incineration facility, there are ash and residues containing DXNs or soluble DXNs. A mud is a filter and an adsorption layer for trapping DXNs, and the main material is composed of mud material D composed of water-insoluble inorganic particles such as stone powder (calcium carbonate, silica stone powder, etc.) or bentonite. As the mud material D, it is preferable to use those having a particle group of 75 μm or more in 10% by mass or less and having an average particle size of 10 μm or less.

  In addition, in consideration of the existence of soluble DXNs, most of them are derived from SS, but as a treatment material A for mud A, inorganic coagulants (PAC, sulfate band, slaked lime, polyiron sulfate, etc.) It is preferable to add an adsorbent (activated carbon, zeolite, etc.) based on an organic coagulant (polyacrylamide, etc.).

  Since the B mud slurry has a change in concentration (washing water is expected to have a low concentration), the slurry is muddy with a mud material D made of clay or stone powder (calcium carbonate, silica stone powder, etc.) as necessary. In addition, in order to insolubilize DXNs trapped in the dewatered cake, an inorganic coagulant (PAC, sulfate band, slaked lime, iron polysulfate, etc.) or an organic coagulant (polyacrylamide, etc.) A cement or lime-based coagulating / solidifying material may be added as the treatment material B. In the case of immediate incineration, the addition of the treated material B is unnecessary.

  (4) DXNs are trapped, adsorbed, insolubilized, and the like in the dewatered cake C (mud A and mud B) by the above-described configuration of the precoat layer, these treatments, additives, and the like. The reduced volume of the dewatered cake C from the filter press 8 is conveyed by a belt conveyor 25, and is melted or fired at a treatment facility or the like that conforms to the new discharge standard. On the other hand, the drainage W is discharged through the drainage tank 9, the neutralization tank 10, and the water discharge monitoring tank 11 at a discharge standard (DXN 10pg-TEQ / L) or less. The filtered water W from the filtered water tank 9 is returned to the supernatant water tank 4 and reused as washing water.

Further, in the illustrated example, since the driving pipes to the filter press 8 share the A mud and the B mud, the residual B mud and the next step A mud in the previous step pipe are mixed at the start of the next step driving, and the A mud is drained. Since DXNs and the like are also mixed in the mixture, a part of the beginning of the mud filtrate discharged is returned to the B mud mixing tank 7 (not shown) and collected in the B mud slurry B _S.

  In addition, although the case where the filter press is used has been illustrated above, the present invention is not limited to this, and other dehydration processing equipment may be used.

[Second embodiment]
The target of the second embodiment is a contaminated mud, and the contaminated mud is a fine-grained soil in which contaminants are concentrated after segregation of coarse particles of sediment or contaminated soil of a port or lake containing DXNs or heavy metals. For example, dredged contaminated sediment is adjusted according to its properties (softness) with fresh water so that coarse particles can be easily separated (or added with vibrating sieve), then trommel, vibrating sieve, scraping gate Separate coarse-grained soil that does not contain harmful substances using a hydrocyclone. The fine-grained soil containing harmful substances after the coarse-grain separation is to be treated. The processing equipment can be similarly processed using the same processing equipment as in FIG. 1 except for the part related to the contaminated cleaning water on the upstream side in FIG.

  The mud A serving as a supplement / adsorption layer for harmful substances such as DXNs is a mud slurry composed of water-insoluble inorganic particles having a particle group of 75 μm or more in an amount of 10% by mass or less and an average particle diameter of 20 μm or less. It is prepared by adding a flocculant and an adsorbent as needed. As the water-insoluble inorganic particles, one or a mixture of two or more of various kinds of clay such as bentonite and kaolinite or coal ash and the like can be suitably used. . Of these, coal ash preferably contains about 2 to 20% of unburned carbon capable of absorbing harmful substances. However, depending on the properties of the coal ash, the particle size distribution may be narrow, and the dewatering resistance of the A mud itself may be too small, even within the range of the predetermined particle size. In this case, before the mud A is completely filled in the filter chamber of the filter press, dehydration proceeds, and it is difficult to form a uniform mud cake. Therefore, if necessary, clay such as bentonite is added to coal ash to adjust the dewatering resistance. Usually, the addition amount of bentonite is preferably 50% or less based on the coal ash.

  These mud materials are hydrated to form a slurry having a water content of 300 to 2000%, preferably 500 to 1700%. When the water content is higher than 2,000% (dilute), the amount of the slurry poured into the filter press increases, the dewatering time becomes longer, and the material separation becomes large, resulting in poor handling. On the other hand, if the water content is lower than 300% (thick), the thickness of the A mud layer becomes uneven, and the required thickness of the A mud must be designed based on the thinnest part. The layer thickness increases and the amount of dewaterable contaminated mud (B mud) decreases.

  In consideration of the fact that the mud slurry does not cause excessive resistance to dewatering of the contaminated mud slurry (B mud) and the possibility of the presence of soluble DXNs and heavy metals, PAC, sulfate band, polyiron sulfate, etc. It is preferable to add an acidic flocculant such as activated carbon and / or an adsorbent such as activated carbon and zeolite. The addition amount of the acidic flocculant such as PAC, sulfate band, and iron polysulfate is 30 to 200 kg / tds · A (addition amount per 1 t of mud material dry matter). The A mud layer also has a function of neutralizing the alkaline drainage since the coagulating / solidifying material added to the contaminated mud described later is generally alkaline. This neutralizing effect also has the effect of properly exerting the ability of the adsorbent described below. That is, depending on the type of organic matter contained in the sediment, the organic matter (COD, TN) may be easily eluted into the filtrate by the action of alkali. ). Depending on the type and amount of the coagulating / solidifying material, the acidic coagulant alone may not be able to neutralize the B mud filtrate. Therefore, by using sodium aluminate together, the alkali neutralizing ability of the A mud is improved. It can also be done.

  Next, in order to increase the dewatering speed and consolidate and insolubilize DXNs trapped in the dewatered cake, a coagulation / solidification material is added to the contaminated mud slurry to prepare B mud.

  As the coagulating / solidifying material, various types of Portland cement, slaked lime, quicklime, or various types of cement-based, lime-based, cement-lime-based solidifying materials, or magnesia-based and magnesia-based coagulating / solidifying materials Add ingredients. The appropriate type of these coagulated / solidified materials is selected by a compounding test using actual target mud.

As magnesia, light-burned magnesia having a BET specific surface area of 10 to 150 m ² / g obtained by calcining magnesium carbonate or the like at about 900 ° C. can be suitably used. The fineness of the fineness is preferably 100 mesh (mesh size: 149 μm), and more preferably 200 mesh (mesh size: 74 μm) to 300 mesh (mesh size: 48 μm).

  Magnesia-based solidifying material is based on magnesia, with lime superphosphate, lime heavy superphosphate, sodium hexametaphosphate, sodium pyrophosphate, sulfate band, iron sulfate, various gypsum, blast furnace slag, various portland cement, alumina cement, etc. , The cohesive performance and solidification strength of magnesia are increased. Generally, the amount of these additives is 20% by mass or less based on magnesia.

  The amount of magnesia and magnesia-based solidified material added to the contaminated mud is usually 30 to 200 kg / tds · B, and the mixing time with the contaminated mud slurry is preferably 0.5 to 3 hours. Magnesia and magnesia-based solidification materials are characterized by a hydration reaction during the mixing time with the contaminated mud, causing the soil particles to aggregate very efficiently, thereby increasing the dehydration rate and greatly increasing the solidification strength. . Therefore, if the stirring time is short, a sufficient dehydration rate cannot be obtained. On the other hand, if the stirring time is too long, the amount of unreacted components that contribute to increasing the strength of the dewatered cake after dehydration decreases, and the elongation of the cake strength decreases.

  These A mud and B mud are cast into a filter press in the order of A mud and B mud. The filter press can use a low pressure (approximately 0.5 MPa) device, and a high-strength cake can be obtained by the effect of the coagulating and solidifying material added to the B mud. However, a high pressure (approximately 4 MPa) device may be used. . In this case, the water content of the cake is reduced, and a higher cake strength is obtained. Therefore, the amount of the coagulating / solidifying material may be reduced. Moreover, you may use the usual flocculant which does not have a solidification function.

  In addition, although the case where the filter press is used has been illustrated above, the present invention is not limited to this, and other dehydration processing equipment may be used.

This example is the case of the contaminated mud of the second embodiment.
(1) Target contaminated mud The characteristics of the target contaminated mud used in Examples and Comparative Examples are shown in Table 1 below. In the filter press dewatering, muddy water was used in which the target mud was classified and washed to remove coarse particles (under 0.3 mm).

(2) Processing Material The materials of the processing materials used in Examples and Comparative Examples are as follows.
Coal ash: Pulverized coal boiler ash with an unburned carbon content of 8% Bentonite: Poly aluminum chloride manufactured by Aso, Nippon Bentonite Co., Ltd .: Alumina content 10% aqueous solution, Magnesia manufactured by Asada Chemical Co., Ltd .: Light burned magnesia, BET Specific surface area 19cm ² / g
Slaked lime: Special name S (particle size 200 mesh or less) manufactured by Ube Materials Co., Ltd.

(3) Dehydration For dehydration, a small filter press (□ 400 × 15 mm × 9 chambers (volume: 15 liters), pump pressure: 0.4 MPa, flow rate: 0.8 m ³ / h) was used.

(4) Drainage test The following measurement was performed on the filtrate to evaluate the dewatering effect.
pH: JIS-K-0102.12.
COD: JIS-K-0102.17
T-N: JIS-K-0102.45
TP: JIS-K-0102.46
DXNs: Official method analysis

(5) Evaluation of dewatered cake: cone index and dissolution test of dewatered cake The dewatered cake obtained in the above (3) was unraveled, passed through a 9.5 mm sieve, and compacted into a mold having a diameter of 10 cm and a capacity of 1 liter. The cone index was measured by a method according to JIS A1228.

  The amount of DXNs eluted from the dehydrated cake was adjusted to pH 7.8 to 8.3 after unpacking the dehydrated cake at the age of 7 days and passing it through a method prescribed in the Coast Guard Law (Announcement No. 14: 2 mm sieve). The mixture was shaken with distilled water for 6 hours, and filtered with a 1 μm glass fiber filter paper) to measure DXNs in the test solution.

Table 2 shows the results of the dehydration experiment using the filter press (Examples 1 to 3 and Comparative Examples 1 and 2). Under the dehydration conditions in the range of the present invention, the dehydration time is shorter than that of a normal dehydration method (combination of PAC and slaked lime as a general flocculant), and the drainage is determined by the effect of the pre-coat layer on the concentration of DXNs based on the drainage. It has been confirmed that it is possible to: Further, the pH became low alkali of 10 or less, and the values of COD, TN and TP became lower than ordinary dehydration. Furthermore, it was confirmed that the strength of the dewatered cake was 7 days or more, and a high strength equivalent to Class II improved soil which is widely used (corn index immediately after loosening and compaction: 800 kN / m ² ) or more was obtained. The amount of DXNs eluted from the dehydrated cake had an insolubilizing effect by agglomeration and solidification of the magnesia-based solidifying material, and all values were 1 pg-TEQ / L or less within the scope of the present invention.

  In addition, although the case where the filter press is used has been illustrated above, the present invention is not limited to this, and other dehydration processing equipment may be used.

[Third embodiment]
In the third embodiment, when a filter press is used for dewatering in the treatment of contaminated water such as cleaning contaminated water, contaminated mud or contaminated soil such as dredged soil, removal and cleaning of residual B mud in the insertion port in the filter press This is a processing technique that forms a cake that is completely wrapped with a mud layer up to the vicinity of the injection port and that is uniformly dehydrated. FIG. 3 shows an example in which the present invention is applied to a treatment facility for cleaning contaminated water.

  In FIG. 3, the processing equipment is the same as the processing equipment of the first embodiment, except for the structure of the filter press and the piping, etc., and it is the same dio lap method as that of the first embodiment, and contains harmful substances such as DXNs. This is a technology that reliably captures harmful substances such as DXNs at low cost and obtains drainage below the discharge standard by using simple processing equipment and processing methods for processing contaminated water and contaminated mud. Further, the mud B slurry composed of contaminated water and the like is dewatered using the mud A layer as a filter and an adsorbing layer, and solid-liquid separated into a dewatered cake and filtrate, and DXNs and the like are contained in the dewatered cakes (A mud and B mud). Harmful substances are trapped, adsorbed, and insolubilized (solidified). In general, when using a filter press, the general procedure is as follows: A mud driving → B mud driving / pressurized dehydration → opening (dewatering cake removal) → closed frame →→→ A mud driving → B mud driving / pressing Dehydration → open frame (dehydrated cake removal) → closed frame → → → The same cycle is repeated below.

  As shown in the roles and procedures of the above-mentioned mud A and mud B, if the mud B composed of clean A mud and harmful polluted water, which is a filter layer, is mixed in the treatment process and the like, naturally, the treatment of the present invention is performed. The meaning of the technology has become smaller, while the A mud and B mud are alternately driven.

(A) Washing of filter press In order to prevent the mixing of A mud and B mud as described above, as equipment, as shown in Fig. 3, mixing tanks 6, 7 for A mud and B mud, a driving pump It is ideal that the 24 and the driving pipe 40 are separated and completely separated. However, even in this case, the injection port in the filter press following the pipe is naturally one system due to its structure. Then, the next step A mud is mixed. Therefore, B mud remaining in the insertion port of the filter press is removed and washed before the A mud implantation in the next step.

  As shown in FIGS. 3 to 5, the filter press 8 is configured by arranging a plurality of filter chambers 42 formed by a pair of filter frames 41 in the pressing direction (center axis). The filter cloth 43 is stuck on the surface of. A flange-shaped filter cloth fixing plate 44 is attached to an end of the filter frame 41 on the center axis side, and a driving hole 45 is formed by the filter cloth fixing plate 44. By being continuous, the driving channel 46 is formed at the center of the press.

  The general procedure of removal / washing is as follows: A mud driving → B mud driving / pressure dehydration → Removal / washing of residual B mud in the injection port → open frame (dehydrated cake removal) → closed frame → → → A mud driving → B mud driving Pressurized dehydration → Removal and washing of residual B mud in the injection port → Open frame (dehydrated cake removal) → Closed frame → → → The same cycle is repeated. Since this method discharges the residual B mud and the washing water in the injection port, a discharge pipe 47 is added to the applicable filter press 8 as shown in FIG.

  The following is a basic specific procedure for removing and cleaning the residual B mud in the injection port.

  (1) After the completion of the B mud driving and pressurized dehydration, the B mud remaining in the driving port is primarily removed by air pressure. That is, first, the consolidation state of the B mud in the driving port is released. As shown in FIG. 3, a compressor 49 is connected to the driving pipe 48 via a three-way valve to supply air into the driving flow path 46 in the press.

  (2) Next, secondary removal is performed. In the secondary removal, as shown in FIG. 5, a plunger (made of rocket-like urethane foam rubber or the like, having a diameter slightly larger than the inner diameter of the insertion port) 50 is inserted through the plunger insertion hand hole 51 of the driving pipe 48, This is done by pressurizing the back of the plunger (air, fresh water, clean bentonite water, etc.). The plunger 50 receives the pressing force on the back surface, scrapes out the residual B mud in the driving hole, and discharges and collects the residual B mud from the discharge pipe 47 together with the residual B mud. Repeat plunger scraping as necessary.

  (3) Next, tertiary removal is performed. The tertiary removal is performed by passing a required amount of fresh water or the like through the driving flow channel 46. As shown in FIG. 3, a water tank 52 of fresh water or the like is installed, and is connected to a mud driving pipe 40a via a three-way valve. The driving pipe 40a for the mud slurry A is connected to the non-press side of the driving pipe 48, and the driving pipe 40b for the mud slurry B is connected to the press side of the driving pipe 48. After these series of cleaning operations, the process proceeds to the next step.

  In addition, as shown in FIG. 3, the cleaning contaminated water stored in the drain tank 53 is configured to be circulated. In addition, the plunger is examined and adopted in size, shape, and material so as to obtain a scraping effect in accordance with the properties of the cake and the structure of the filter press.

  In addition, depending on the muddy water property such as containing a large amount of sand, it is supposed that dehydration is excessively promoted and dehydration hardens to the mud in the driving hole. In such a case, it may not be possible to cope with the above-described method based on simple primary to tertiary removal. In such a case, a mechanical perforation method is used prior to the primary removal. This can be dealt with by a conventional insertion rotary type maintenance equipment for drainage facilities (a well-known product name is Cantool). After the perforation, the above primary to tertiary removal is used together.

  By the way, originally, the present technology also has a feature that a general-purpose filter press can be applied almost as it is (without major modification). Therefore, it is conceivable to employ various filter presses in actual work or the like. Therefore, it is expected that the structure of the inner surface of the driving hole is also various. For example, a structure in which the inner surface of the driving hole is not smooth may be considered. Basically, it is premised that plunger scraping can be carried out as described above, so it is necessary to make advance modifications to a structure that allows plunger scraping. If you look, there is no problem.

(B) Structure of Filter Press FIG. 4 shows a filter plate configuration of a general-purpose filter router press. The basic mechanism of filter root press dewatering is that, by driving pressure mud, only the water in the mud (strictly, ultrafine soil smaller than the filter cloth passes) passes through the filter cloth, and soil particles larger than the filter cloth Is left inside the filter cloth, so that solid-liquid separation can be achieved. On the other hand, the following phenomena have been confirmed from many examples in the past of filter press dewatering. Although the required dehydration can be achieved as a whole of the dehydrated cake, the dehydration state in the vicinity of the center of the cake C is not sufficient and the cake C is in a semi-solidified state or a semi-liquefied state C ′. This factor can be inferred from the basic mechanism and the filter plate structure described above.

  (1) As shown in FIG. 4, a flange-shaped filter cloth fixing plate 44 for fixing the filter cloth 43 is present around the driving hole 45 at the center of the filter plate. (2) The filter cloth fixing plate 44 is made of, for example, bakelite and is made of a material and structure that does not allow moisture to pass therethrough. (3) Therefore, the dehydration state is remarkably inferior in the vicinity of the cake center compared with other parts. (4) It is also assumed that the B mud layer is completely wrapped with the A mud layer so that the B mud does not come into direct contact with the filter cloth. However, the possibility of mixing with the drainage becomes extremely high), but in places where water does not generally pass through the center side of the flange diameter, formation of the mud layer A is impossible because water does not pass through. Conversely, on the filter cloth surface through which moisture permeates, formation of the mud layer A is reliable.

  Focusing on these factors, a method was devised in which the dehydration of water in the muddy water located at the center from the flange diameter could be promoted and the formation of the A mud layer was reliable. Before describing the invented method, this need is first addressed. As shown in the above-mentioned washing of the filter press, the B mud remaining in the insertion port of the filter press can be solved by a method of removing and washing before the next step of A mud implantation. However, the method described above cannot remove and wash mud in the “semi-solidified or semi-liquefied state” existing on the outer peripheral portion from the injection port.

  On the other hand, if the semi-solid / liquid mud existing outside the injection port completely separates and falls off as a dehydrated cake at the time of opening the frame, there is not much problem at the time of the next step A mud driving, but the semi-solid / liquid In the actual state, the semi-solid / liquid mud is almost certainly attached to the filter cloth or the filter cloth fixing plate when the cake is taken out. Further, since the filter cloth fixing plate is made of a material and a structure that does not allow moisture to pass through, the A mud layer is not formed substantially on the center side of the flange diameter. Therefore, the semi-solid / liquid state B mud directly adheres to the filter cloth or the like.

  Therefore, as shown in FIG. 5, an auxiliary filter cloth 60 was stuck on a flange-shaped filter cloth fixing plate 44 in order to ensure water permeability up to a portion immediately adjacent to the insertion port 45. The auxiliary filter cloth 60 is attached to the inner side surface of the filter cloth fixing plate 44 and is continuously integrated with the filter cloth 43. An experiment was conducted to confirm the actual effect of this method, and the following results were obtained. (1) A uniform dewatered cake including the central part of the dewatered cake was formed. (2) A mud layer could be formed right near the injection hole.

  The addition of the above two methods (a method of removing and cleaning residual B mud in the injection port and a method of forming a uniform dewatered cake completely wrapped with the A mud layer by securing water permeability to the area immediately adjacent to the injection port) further expands the diop wrap method. It was done.

(C) Correspondence to long and long filter press The above shows the means of expanding the diolapping method. As described above, the application of this method is a washing water treatment containing DXNs and the like in a dismantling operation of a waste incineration facility, and a dehydration, volume reduction, and insolubilization (solidification) treatment of a sediment containing DXNs and the like. In general, the target amount of the dewatering / reducing / insolubilizing treatment of the sediment is large, so that a large filter press is naturally used. Large filter presses not only increase the size of the filter frame, but also increase the number of filter chambers. Accordingly, the length of the pipeline of the injection port becomes longer, and the flow resistance of the semi-solid / liquid mud remaining in the injection port becomes larger. Therefore, in the plunger removal / cleaning method using the mere air pressure and pressure water described in the above-described filter press cleaning, a situation in which the flow resistance is larger than the pressure of air / water may be considered. Cleaning becomes difficult or impossible.

  Therefore, a method for removing and cleaning when the length of the pipeline at the insertion port is long (large flow resistance) when using a large filter press or the like was devised. As shown in FIG. 6, a branch-type discharge pipe 70 for residual mud in the injection port (hereinafter referred to as a branch discharge pipe) is provided in a form that partitions the middle of the driving flow path. By providing the branch discharge pipes 70 at arbitrary intervals, it is possible to avoid the relationship that the flow resistance becomes larger than the pressing force. At the same time, an automatic opening / closing control valve 71 is provided in the branch discharge line 70, and an opening / closing control function such as an independent opening / closing operation is added.

  A specific control example of the branch discharge pipe will be described below. After closing the four branch discharge pipes 70 → A mud driving → B mud driving / pressure dehydration, the branch discharge pipe 70a is opened, and the branch discharge pipes 70b to 70d are closed, and the inlet end to the branch discharge by air pressure. The remaining mud up to the pipe 70a is removed by one stage. Next, the branch discharge pipe 70a is closed, 70b is opened, 70c · d is closed, and then the air is pressurized to remove two-stage residual mud between 70a and 70b. The same procedure is repeated to perform 3.4 step removal. In this way, the flow resistance in the pipe is temporarily released stepwise for each section, and thereafter, cleaning is performed by the same method using plunger and fresh water as described above. This method is an example, but it is possible to cope with a long filter press by making the best use of the above-mentioned method depending on the situation.

[Fourth embodiment]
This fourth embodiment is a treatment technique for decomposing harmful substances such as DXNs in mud filtration water B with a photocatalyst, filtering solids, and treating the filtrate to a discharge standard or less. Applied to the treatment of contaminated water. It can also be applied to the treatment of contaminated mud and contaminated soil such as dredged soil. FIG. 7 shows an example applied to the treatment of cleaning contaminated water.

  The embodiment of FIG. 7 is, for example, a technology for treating DXNs in facility cleaning sewage performed at the time of dismantling a waste incineration facility. The contaminated water generated in the cleaning operation is incinerated ash and facility structure surface debris as solids, As harmful organic substances, there are DXNs and the like which do not dissolve in water relatively firmly adhered to solids, DXNs and the like dissolved in washing water. This treatment technique is a method of efficiently separating and decomposing DXNs having different existing forms, and is roughly divided into two stages. That is, the first step is a solid-liquid separation in contaminated water and a dehydration step of removing a part of DXNs and the like dissolved in water, and the second step is a photocatalytic decomposition of DXNs and the like and DXNs and the like dissolved in the filtrate. It comprises a step of filtering off the adsorbed solids. The drainage water is discharged below the discharge standard for DXNs, etc., and the reduced volume of the dewatered cake is melted or burned (incinerated) at treatment facilities (eg, industrial waste incineration facilities) that comply with the new discharge standards. This is a processing method of the environmental load reduction type that decomposes.

  More specifically, in FIG. 7, the dewatering step is the same as that of the first embodiment, and the same processing apparatus as that of the first embodiment is used except for the processing apparatus of the mud filtrate B. That is, similarly to the first embodiment, the mud A is a layer for capturing adsorbed solids such as DXNs and the like, and an adsorbing layer for water-soluble DXNs. Accordingly, an adsorbent (treatment material) A such as an inorganic or organic coagulant or activated carbon or zeolite is added.

  Next, in the filter press 8, B mud is driven in after A mud. B mud is settled sludge water excluding supernatant water, and is dehydrated through a precoat layer (A mud layer), and solid-liquid separated into a dewatered cake C and filtrate W. When the solid content concentration in B mud is low, it can be dealt with by adding mud material D. In addition, a cement-based or lime-based solidifying material (treatment material) B can be added to the B mud as necessary in order to prevent re-mudification of solids. However, the solidified material B is not required to be carried out for immediate incineration without temporary storage.

  As described above, most of the water-soluble or insoluble DXNs can be finally captured in the dehydrated cake C by the dehydration step alone. On the other hand, the drainage water W after dehydration is conventionally reduced to a drainage standard (DXN 10 pg-TEQ / L) or less through a drainage tank 9 and, if necessary, a neutralization tank 10 and a monitoring tank 11 to a public water area. In the present invention, DXNs and the like are decomposed by the photocatalytic fiber. In this step, the filtrate is taken from the drainage tank 9 or the neutralization tank 10 into the photocatalytic fiber decomposing device 30 and decomposed by using a plurality of decomposing devices 30 in series or in parallel according to the throughput of the filtrate. Usually, this decomposition is performed by circulating the drainage water, so that a water storage tank 31 having a required capacity is provided. The filtrate that has decomposed DXNs and the like is finally discharged from the monitoring tank 11 to public waters.

  In addition, although the case where the filter press is used has been illustrated above, the present invention is not limited to this, and other dehydration processing equipment may be used.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic of the equipment flow which shows an example of the processing equipment for implementing the basic processing method of this invention. It is sectional drawing which shows the basic process in the filter press of this invention in order of a process. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic of the equipment flow which shows an example of the processing equipment which added the washing | cleaning method of the filter press etc. to the basic processing method of this invention. It is sectional drawing which shows the filter plate structure, cake image, etc. of a general purpose filter press. It is sectional drawing which shows the filter plate structure, cake image, etc. of the filter press of this invention. It is sectional drawing of the press which shows removal and washing | cleaning of the mud in the injection port flow path of this invention in a long filter press. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic of the equipment flow which shows an example of the processing equipment which added the drainage processing with a photocatalyst to the basic processing method of this invention.

Explanation of reference numerals

A _S : A mud slurry B _S : B mud slurry C: Dewatered cake D: Mud material W ₀ : Contaminated water W: Filtration water 1: Cleaning nozzle 2: Contaminated water collecting pit 3: Gravel sand Separation device 4 ... Supernatant tank 5 ... Storage tank 6 ... A mud mixing tank 7 ... B mud mixing tank 8 ... Filter press 9 ... Filtration tank 10 ... Neutralization tank 11 ... Water discharge monitoring tank 12 ... mud tank 13 ... dissolution tank A
14 Dissolution tank B
20 transfer pump 21 stirrer 22 high-pressure injector 23 transfer pump 24 driving pump 25 belt conveyor 30 disassembling device 31 water reservoir 40 driving piping 41 filter Frame 42 Filter chamber 43 Filter cloth 44 Filter cloth fixing plate 45 Driving port 46 Driving flow path 47 Drain pipe 48 Driving pipe 49 Compressor 50 Plunger 51 …… Plunger insertion hand hole 52 …… Water tank 53 …… Drain tank

Claims (13)

  This is a method for treating contaminated mud containing contaminated water, dredged soil, and other contaminated substances containing harmful substances. A mud slurry composed of mud material that captures harmful substances is cast into a dehydration chamber. A mud slurry B composed of an object to be treated for pollution containing harmful substances is cast into the mud slurry A, and then the mud slurry is dewatered using the mud layer A as a pre-coat layer to form a dewatered cake and drainage water. A method for treating an object to be contaminated, wherein solid-liquid separation is performed, harmful substances are reliably captured in a dewatered cake, and drainage is treated to a discharge standard or less.   2. The treatment method according to claim 1, wherein the mud material of the A mud slurry comprises water-insoluble inorganic particles having a particle group of 75 μm or more in an amount of 10% by mass or less and an average particle diameter of 20 μm or less. The method of treating the object to be contaminated.   The treatment method according to claim 2, wherein the water-insoluble inorganic particles are mud material composed of one or two or more kinds of stone powder or bentonite in the case of treating contaminated water, and in the case of treating contaminated mud, A method for treating an object to be treated for contamination, characterized by being a mud material comprising one or a mixture of two or more of clay, stone powder and coal ash.   In the treatment method according to any one of claims 1 to 3, one or two of an inorganic coagulant, an organic coagulant, and an adsorbent in the case of treating contaminated water in the A mud slurry. A method for treating an object to be treated for contamination, characterized in that in the case of treating contaminated mud, one or more of an inorganic coagulant and / or an adsorbent are added.   5. The treatment method according to claim 1, wherein at least one of clay and stone powder is added to the B mud slurry in the case of treating contaminated water. How to process the object.   The treatment method according to any one of claims 1 to 5, wherein the B mud slurry contains an inorganic coagulant, an organic coagulant, or a cement or lime-based coagulant when treating contaminated water. One or more solidified materials are added, and in the case of treatment of contaminated mud, one or two or more coagulated and solidified materials such as cement, lime, and magnesia are added. A method for treating a contaminated target object.   The processing method according to any one of claims 1 to 6, wherein a filter press is used for the dehydration processing.   The method for treating a contaminated object according to any one of claims 1 to 7, wherein a part of the A mud filtrate that has started to be discharged in the dehydration treatment is collected in a B mud slurry. .   In the treatment method according to any one of claims 1 to 8, in the case of treating contaminated water, the contaminated water obtained by washing the facility is separated into solid and liquid, and the supernatant water is reused as washing water. And supplying the sediment as a B mud slurry to the next step.   The treatment method according to any one of claims 1 to 9, wherein a plurality of filter chambers are arranged in a press direction for a dehydration treatment of the A mud slurry and the B mud slurry. A shape capable of temporarily removing the residual B mud at the injection port by supplying air pressure from the outside to an injection flow path that is continuous from the injection port formed in the filter chamber in the press direction, and then closing the cross section of the injection flow path. A secondary removal by passing the scraper through the driving flow path, and then performing a tertiary removal by passing fresh water through the driving flow path.   The treatment method according to any one of claims 1 to 10, wherein a surface of a filter cloth fixing member provided at a driving port of a filter chamber of a filter press for performing dehydration treatment of A mud slurry and B mud slurry. A method for treating an object to be contaminated, wherein an auxiliary filter cloth continuous with the filter cloth is provided.   The treatment method according to any one of claims 1 to 11, wherein a harmful substance in the filtrate of the B mud slurry is decomposed by a photocatalyst, a solid content is separated by filtration, and the filtrate is treated to a wastewater standard or lower. A method for treating a contaminated target object. 13. The processing method according to claim 12, wherein the decomposition of the harmful substance is performed from a composite oxide phase of an oxide phase mainly composed of a silica component (first phase) and a metal oxide phase other than silica (second phase). A filter comprising a woven fabric of a silica-based composite fiber having a photocatalytic function in which the proportion of at least one component of the second phase is inclinedly increased toward the surface layer of the fiber, and an ultraviolet lamp. A method for treating an object to be contaminated, wherein the method is performed by a purification device provided.

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