JP3521076B2 - Sludge treatment device and sludge treatment method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sludge treatment apparatus and a sludge treatment method, and more specifically, sludge that is made harmless by separating harmful substances from sludge containing harmful substances and can be used as a backfill material. The present invention relates to a treatment device and a sludge treatment method.

[0002]

2. Description of the Related Art When sludge is treated, since sludge generally contains a large amount of water, it is necessary to separate sludge from water, that is, solid-liquid separation. However, the properties of sludge depend on the state of raw water and the coagulant used, and its components are generally composed of aluminum hydroxide, clay, colloids, microorganisms and other organic and inorganic substances, and have a high water content. It is gelatinous. Therefore, the filterability is poor, and the water content of the separated sludge is high, which causes a considerable burden on post-treatment such as transportation costs and landfill incineration. Therefore, a method of utilizing the aggregating action by chemical injection before post-treatment is used. When lime and ferric chloride, which are inorganic coagulants, are used as injection chemicals, the filterability is improved, but there is a problem that the amount of sludge to be disposed increases by injecting the chemicals.

Therefore, as a sludge treatment method for solving this problem, a method of freeze-thawing sludge using a freeze-thaw apparatus has been developed. For example, JP-A-5-263417
Japanese Unexamined Patent Publication (Kokai) discloses a technique in which raw sludge is subjected to freeze-thawing treatment to modify soil having a large amount of clay to a soil close to general soil having a large amount of silt, and used as a backfill material.

[0004]

However, when sludge is contaminated with harmful substances such as dioxins, PCBs, environmental hormones, persistent substances (POPs), and pesticides, simply freezing and thawing it is harmful. The substance cannot be rendered harmless and, of course, such sludge cannot be used as a backfill material. That is, since these harmful substances are highly toxic or chemically stable, it is required to surely separate and decompose these harmful substances to reduce their toxicity or render them harmless. In particular, since the sludge itself contains a large amount of water, the treatment itself is troublesome and time-consuming, and in the case of sludge containing harmful substances, a long treatment step for decomposing and detoxifying the harmful substances, The current situation is that large-scale equipment is required and a great deal of processing cost is required.

Therefore, in view of the above-mentioned problems of the prior art, the object of the present invention is to effectively treat harmful substances contained in contaminated soil or sludge containing a large amount of water without requiring a large treatment cost such as large-scale combustion equipment. Can be decomposed
An object of the present invention is to provide a sludge treatment device and a sludge treatment method that can be used as backfill materials.

[0006]

The above objects can be achieved by the inventions described in the claims. That is, the sludge together with characterizing feature of the sludge treatment apparatus according to the present invention, for storing the sludge
A freezing and thawing apparatus having a mud supply tank for adding and stirring a chemical for extracting harmful substances therein , a freeze thaw apparatus having a freeze thaw tank capable of freezing and thawing the sludge sent from the mud supply tank, and the freeze thaw A specific gravity separation device, which is connected to a tank and is capable of separating the above-mentioned chemical agent, which has extracted the harmful substances in the freeze-thawed sludge, from the other components by a specific gravity difference.

According to this structure, even sludge containing a large amount of water is efficiently dehydrated by the freeze-thaw device, and the harmful substances in the sludge are reliably separated from the sludge by the action of the chemical agent for extracting the harmful substances. As a result, sludge from which harmful substances have been removed can be effectively used as a backfill material. Therefore, if there is a suitable exhaust heat source such as an incinerator at the site where sludge is generated, it is possible to drive the freeze-thaw device by using that heat source to enable on-site treatment and separate harmful substances. The modified sludge can be used as a backfill material.

[0008] As a result, it is possible to effectively decompose harmful substances in contaminated soil or sludge containing a large amount of water without using large-scale combustion equipment and a great deal of treatment cost, and it can be used as a backfill material. It was possible to provide a sludge treatment device that does.

In the present invention, the term "sludge" is used to generically refer to a dirty mud substance containing a relatively large amount of water, including sludge generated in water treatment plants and sewage treatment plants, industrial wastewater treatment sludge, and landfill wastewater treatment. It is used as a concept that includes all types of sludge such as sludge and human waste treatment sludge.

The freeze-thaw tank of the freeze-thaw apparatus is the sludge.
Is frozen and thawed with an ammonia absorption refrigerator.
In, equipped with a cooling tower for cooling the absorption refrigerator,
Freeze the cooling of the absorber that constitutes the ammonia absorption refrigerator.
Using the cold heat source that is generated when the sludge is melted
Cormorants it is preferable. According to this configuration, the drive energy of the refrigerator is
Further energy saving by lowering the energy of the energy and increasing the coefficient of performance
It is possible to achieve ruggedness and power saving.

Separated by the specific gravity separator and discharged.
It is preferable to provide a dehydrator for dehydrating the sludge. According to this configuration, the sludge from which the harmful substances have been removed is further dehydrated, so that it becomes easy to effectively use the sludge as general soil for various purposes.

[0012] It is preferable that the medicine from which the harmful substance is extracted is decomposed and connected to a decomposition treatment facility capable of detoxifying the harmful substance.

According to this structure, the drug containing the harmful substance can be surely rendered harmless, which is convenient.

It is preferable to have a premixing tank for preparing a premixture of sludge and ice nucleation active protein-like substance, and a mechanism for charging the premixture from the premixing tank to the freeze-thaw tank.

According to this constitution, by putting the mixture mixed in the premixing tank into the freeze-thaw tank, the freezing start temperature of the sludge rises and the ice-nucleus active protein-like substance uniformly dispersed is frozen from the periphery. With the large number of fine sludges that have started freezing as cores, the freezing of sludge in the freeze-thaw tank can be efficiently grown without unevenness, and the freezing efficiency can be made extremely high.

Further, the characteristic constitution of the sludge treatment method according to the present invention is that sludge is stored and that the sludge contained in the stored sludge.
Add a chemical to dissolve and extract harmful substances and stir
Freeze-thaw the sludge from which the harmful substances have been extracted.
Frozen and thawed in the
The drug from which harmful substances are extracted and other components are separated by the difference in specific gravity.
To separate .

According to this structure, the harmful substances in the contaminated soil or sludge containing a large amount of water can be effectively decomposed and treated as a backfill material without requiring a large-scale combustion facility or the like and a large treatment cost. A sludge treatment method that makes available can be provided.

The freeze-thaw device converts the sludge into ammonia.
Freeze and thaw with an absorption refrigerator, and
Frozen cooling of the absorber that makes up the monia absorption refrigerator
Use the cold heat source generated when the sludge is melted
Is preferred. According to this configuration, the drive energy of the refrigerator is
-Lower temperature and higher coefficient of performance, further energy saving
Reduction and power saving can be achieved. It is preferable to further dehydrate the sludge from which harmful substances have been separated. According to this configuration, sludge can be effectively used for various purposes as general soil, which is convenient.

It is preferable to further decompose the drug from which the harmful substances are extracted. According to this configuration, the drug containing the harmful substance can be rendered harmless, which is convenient.

When the sludge is frozen, it is preferable to put a mixture of the sludge and the ice nucleus active protein-like substance prepared in advance into the freeze-thaw apparatus.

According to this structure, since a mixture of sludge and ice nuclei active protein-like substance is prepared in advance, they are uniformly mixed and mixed, and when this is put into a freeze-thaw tank, the ice nuclei active protein-like substance is mixed. With the presence of the substance, the freezing start temperature of the sludge rises, and the freezing starts around the uniformly dispersed ice nuclei active proteinaceous substance. The sludge can be efficiently grown without causing unevenness, and the freezing efficiency can be made extremely high. Therefore,
This is convenient because the filtration specific resistance during dehydration becomes small, water can be easily removed, and the dehydration step can be performed more efficiently.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic structure of a sludge treatment device according to this embodiment. This sludge treatment device has a sludge supply tank 1 for temporarily storing sludge containing harmful substances such as dioxins, and a freeze-thaw tank 2 for freezing and thawing the sludge sent from the sludge supply tank 1. Thawing device for reforming silt to a silty substance, specific gravity separation device 3 for separating harmful substances in sludge by specific gravity difference, and sludge reformed to silty substance by separating and removing harmful substances by this specific gravity separation device 3. It is configured to include a dehydrating device 4 for dehydrating.

The mud supply tank 1 stores a predetermined amount of sludge contaminated with harmful substances, and also agitates the stored sludge with a stirrer 5 to dissolve the harmful substances and extract an organic solvent (toluene, Dichloromethane, hexane, alcohols, etc.) are supplied. The drug to be used is not particularly limited as long as it can be separated (insoluble in water) by the difference in specific gravity with water and can dissolve and extract harmful substances.

The sludge sufficiently mixed with the organic solvent in the mud supply tank 1 is sent to the freeze-thaw tank 2 by the feed pump P. The principle of the freeze-thaw method pays attention to the fact that the water contained in sludge and the water adhering to the surface of the sludge exist, and when frozen, the water grows as ice crystals. When the particles are pushed by, the fine particles are combined into a large block and concentrated while condensing to improve the filtration characteristics. Furthermore, when the whole is frozen, the expansive force of ice formation gives a strong compressive force to the sludge, which destroys the sludge structure (protein or carbohydrate micelle structure or gel-like structure of gel-like substance) and The contained water flows out, and the dehydration effect becomes higher.

The freeze-thaw tank 2 is connected to the refrigerator 6, and the sludge in the freeze-thaw tank 2 is frozen by indirect contact with the refrigerant sent from the refrigerator 6 through the pipe.
Then, water in the sludge is discharged, and the frozen sludge is heated and melted and sent to the specific gravity separator 3 in the next step.

The refrigerator 6 is not particularly limited, but it is preferable to use an ammonia absorption refrigerator.
When ammonia is used as the refrigerant, it is convenient because it functions as a refrigerant that is inexpensive and has excellent thermodynamic properties without using CFCs that are harmful to the environment. As will be described later, the ammonia absorption refrigerator has a condenser that radiates and liquefies ammonia as a refrigerant, an evaporator that evaporates ammonia, and an absorber that absorbs the ammonia vapor evaporated in this evaporator into water that is an absorbent. And is configured. Then, a generator that pressurizes and feeds an aqueous ammonia solution sufficiently containing a refrigerant by an absorber with a solution pump, and a rectifier that raises the concentration of ammonia and sends it to a condenser may be provided. Furthermore, as a drive source for operating the absorption refrigerator, waste heat energy such as incineration of sludge and cogeneration may be supplied.

The specific gravity separation device 3 dissolves and extracts the harmful substances in the sludge in an organic solvent, and separates the harmful substances by the difference in specific gravity between the organic solvent and water. In this case, the harmful substances are extracted. The organic solvent has a smaller specific gravity than water and floats upward in the specific gravity separator 3. Therefore, the organic solvent separated above is removed to the outside of the specific gravity separation device 3 by pumping it out using an appropriate discharge device. Then, the water is discharged from the upper part of the sludge, and the modified sludge is discharged from the bottom part.

The harmful substances whose specific gravity has been separated together with the extract by the specific gravity separating device 3 are sent to a decomposition treatment facility 7 for decomposing the harmful substances. The decomposition treatment facility 7 may be a device such as a rotary kiln that decomposes by a high temperature thermal decomposition method, or an apparatus that decomposes by a chemical extraction decomposition method using NaOH or the like, and further metal sodium. It may be a decomposition treatment apparatus by the method, a decomposition treatment apparatus by the supercritical water oxidation method, or a combination apparatus capable of decomposing treatment by ultraviolet irradiation and microorganisms.

The sludge accumulated at the bottom of the specific gravity separator 3 is further sent to a dehydrator, where it is further dehydrated. The dehydration here is performed in a relatively short time because the dehydration from the sludge has progressed considerably in the freezing and thawing tank 2, and the dehydration efficiency is high. Therefore, according to this embodiment, the energy cost required for the dehydration process can be reduced.

The dehydrated sludge is a modified sludge having a relatively low viscosity and a large amount of silt, and can be effectively used as a backfill material. In other words, by freezing and thawing sludge with a high water content using a freeze-thaw device, coarsening of the particles that make up the sludge progresses,
Clay with fine particles is modified to silty with large particles. As a result, the water permeability is improved and it can be used as general soil for various purposes. In order to promote the reforming of sludge, freezing and thawing may be repeated multiple times by a freeze-thaw device.

[Other Embodiments] (1) As shown in FIG. 2, a freeze-thaw tank 2 in which sludge contaminated with harmful substances is frozen and thawed by an absorption refrigerator 6.
And a cooling tower T for cooling the absorption refrigerator 6, and a pre-mixing tank 20 for preparing a pre-mixture of sludge and ice nucleus active proteinaceous substance in advance, and a freeze-thaw tank for pre-mixing the pre-mixture from the pre-mixing tank 20. When the sludge is frozen, it may have a mechanism for throwing it in 2 to put the mixture of the sludge and the ice nucleus active protein-like substance prepared in advance into the freeze-thaw tank 2 to freeze / thaw it. .

That is, the absorption refrigerating machine 6 absorbs the condenser C for liquefying a refrigerant such as ammonia by heat radiation, the evaporator E for evaporating ammonia, and the ammonia vapor evaporated by the evaporator E into the water as the absorbent. And an absorber A that causes the absorption. The absorber A is equipped with a generator that pressurizes and feeds an aqueous ammonia solution containing a sufficient amount of refrigerant with a solution pump (not shown), and a rectifier that raises the ammonia concentration and sends it to the condenser C. You may let me. Furthermore, as a drive source for operating the absorption refrigerator 6, although not shown, it is preferable to supply waste heat energy such as incineration of sludge and cogeneration.

The high-pressure, high-concentration ammonia vapor is sent to the condenser C, where it is heat-exchanged with the cooling water from the cooling tower T and condensed and liquefied. The condenser C may be provided with an extraction device that removes a gas component that does not condense. Since the non-condensable gas deteriorates the heat transfer characteristics such as condensation or absorption, it is convenient to remove the non-condensed gas because the heat transfer characteristics can be maintained well. Incidentally, FIG.
Reference number 14 is a cooling water pump for sending cooling water.

Further, a brine circuit is connected to the evaporator E and the absorber A. This brine circuit includes a cold brine circuit B1 including a low temperature cold brine tank 11 and a cold brine pump 12 that feeds cold brine, a hot brine tank 9 and a hot brine pump 10 that feeds warm brine. And a pair of cold temperature switching valves 13 and 13 'for switching between the hot brine circuit B2 and the cold brine circuit B1. A cold brine circuit B1 is connected to the evaporator E, and a warm brine circuit B2 is connected to the absorber A.
Are connected. When the sludge sent to the freeze-thaw tank 2 is frozen, the cold brine cooled by the evaporator E of the absorption refrigerator 6 is sent directly to the freeze-thaw tank 2 to freeze the sludge. It should be noted that reference numeral 17 is a heat storage tank, and for example, cold heat is guided to this heat storage tank at night in summer to perform ice heat storage, and heat is guided to the heat storage tank at night in winter and used as hot water. Of course, the heat storage tank 17 is not always necessary in the present embodiment, but if it is provided, the heat can be effectively used and the power consumption can be reduced, which is convenient.
Drawing number 8 and 8'is a switching valve for utilizing the heat storage tank 17, and drawing number 15 is a brine heat exchanger.

As the ice nucleation active protein-like substance,
Erwinia herbicola and Pseudomonus fl are ice-nucleating bacteria
Uorescens, Pseudomonas syringage, etc. are cultivated by using L medium or the like to collect the bacteria, physically destroy and sterilize them, and lyophilize them, and then pulverize them into powder form.

In this way, a mixture of sludge and ice nuclei active protein-like substance is prepared in advance, so that these are mixed uniformly and mixed, and when this is put into a freeze-thaw tank, the ice nuclei active protein-like substance is mixed. The freezing temperature of the sludge rises due to the presence of the sludge, and the freezing starts around the uniformly dispersed ice nuclei active proteinaceous substance. The freezing can be efficiently grown without causing unevenness, and the freezing efficiency can be made extremely high. Therefore,
The filtration specific resistance at the time of dehydration becomes small, water is easily eliminated, and the dehydration process can be efficiently performed. In addition, since the ice nucleation active protein-like substance used is obtained from ice nucleation active bacteria and does not remain viable, it does not cause contamination or other problems, is easy to handle, and has high work efficiency. Is. By efficiently freezing an object to be treated such as sludge, the energy required for freezing can be reduced, and moreover, the efficiency of the dehydration treatment in the next step can be improved to further improve the dehydration property.

(2) In the above embodiment, the absorber constituting the ammonia absorption refrigerator may be cooled by the cold heat source generated when the frozen sludge is melted. In other words, the absorber is normally cooled by a cooling tower, but if a cold heat source generated when the frozen sludge is thawed is used in addition to this, the driving energy of the refrigerator is lowered and the coefficient of performance is increased. Further, energy saving and power saving can be achieved.

(3) The hot brine circuit and the cold brine circuit may be always operated for a plurality of freeze-thaw tanks. That is, the cold brine circuit is operated to freeze the sludge in one freeze-thaw tank, while the warm brine circuit is operated to thaw the sludge already frozen in the other freeze-thaw tank. By sequentially performing such an operation on a plurality of freeze-thaw tanks, the pre-dewatering treatment of sludge can be efficiently performed, and the treatment efficiency can be increased.

(4) In the above embodiment, an example was shown in which an organic solvent for extracting harmful substances was introduced into the mud supply tank, but instead of this, the organic solvent may be introduced into the specific gravity separator. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a sludge treatment device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a freeze-thaw device that constitutes a sludge treatment device according to another embodiment.

[Explanation of symbols]

1 mud tank 2 Freeze-thaw tank 3 Specific gravity separator 4 dehydrator 7 Decomposition equipment 20 premixing tank

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-11-5099 (JP, A) JP-A-4-126600 (JP, A) JP-A-54-4278 (JP, A) JP-A 64-- 70199 (JP, A) JP-A-2-76595 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 11 / 00-11 / 20

Claims (6)

(57) [Claims] 1. The sludge is stored and harmful in the sludge.
And feeding the mud tank for stirring was charged with drug for extracting a substance, the
And freeze-thaw device having a freezing molten bath possible freezing and thawing the sludge fed from the paper sludge tank, which is connected with the freezing molten bath, said agent extracted harmful substances freeze-thaw treated sludge A sludge treatment device comprising: a specific gravity separation device that can separate the other components by a specific gravity difference. 2. A freeze-thaw tank of the freeze-thaw apparatus is provided with the dirt.
When mud is frozen and thawed by ammonia absorption refrigerator
Both are equipped with a cooling tower for cooling the absorption refrigerator,
For cooling the absorber that constitutes the ammonia absorption refrigerator,
Utilizing the cold heat source generated when the frozen sludge is thawed
The sludge treatment device according to claim 1, which is performed . 3. Sludge and ice nucleation active protein-like substance in advance
A premix tank to create a premix of
The sludge treatment device according to claim 1 or 2, which has a mechanism for charging the premixed mixture into the freeze-thaw tank . 4. Sludge is stored and contained in the stored sludge.
Add a chemical to dissolve and extract the harmful substances
Freeze the sludge to which this chemical has been added and the harmful substances have been extracted.
Freeze / thaw treatment by freeze / thaw device, freeze / thaw treatment
Specific gravity difference between chemicals that extracted harmful substances in sludge and other components
Sludge treatment method to separate by. 5. The freezing and thawing device ammonifies the sludge.
A) Freezing and thawing with an absorption refrigerator,
Freeze the cooling of the absorber that constitutes the
A contract performed using the cold heat source generated when the sludge is melted
The sludge treatment method of claim 4 . 6. It was prepared in advance when the sludge was frozen.
The sludge and the ice nucleus active protein-like substance were uniformly dispersed.
A premix is charged into the freeze-thaw apparatus.
Sludge treatment method.