JP3271621B1 - Cleaning method of waste incinerator equipment - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To efficiently treat and reuse cleaning wastewater generated when high-pressure water removes contaminants attached to an incinerator facility when dismantling a waste incinerator facility or the like. After adding a dithiocarbamic acid-based chelating agent to the washing wastewater in the first reaction tank 1 to insolubilize Pd, Cd, and Hg, powdered activated carbon is added in the second reaction tank 3 to adsorb dioxins, and the third reaction is further performed. In a tank 4, a ferrous salt is added to reduce Cr, Se, As to insolubilize, and then in an agglutination reaction tank 5, an inorganic coagulant and an organic coagulant are added to perform coagulation treatment. The treated water is separated by the vessel 11 and reused for high-pressure water washing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning and removing contaminants adhered to an incinerator with high-pressure water when dismantling a refuse incinerator, and more particularly to treating wastewater generated by the high-pressure water cleaning. The present invention relates to a method for cleaning waste incinerator equipment which is reused as cleaning water.

[0002]

2. Description of the Related Art In incinerators such as refuse incinerators, during combustion, organic compounds such as phenol, benzene and acetylene, chlorinated aromatic compounds such as chlorophenol and chlorobenzene, and dioxin precursors such as chlorinated alkyl compounds. The body develops. These dioxin precursors are catalyzed by fly ash in the presence of organochlorine compounds such as polychlorinated-p-dibenzodioxins (PCDD), polychlorinated dibenzofurans (PCDF), and coplanar polychlorobiphenyl (hereinafter referred to as these). Are collectively referred to as "dioxins").

[0003] The generated dioxins are removed by a dioxin decomposer or adsorbent added during the incineration operation of refuse, or contained in incineration ash and discharged from the incinerator, and then decomposed. Some of them adhere to the furnace walls, flue, etc. and remain. Some of the dioxins adhere to ash and the like remaining in the incinerator and remain in the incinerator.

[0004] In the incinerator, heavy metals contained in waste such as incinerated garbage remain in ash and the like.

[0005]

[Table 1]

Incidentally, when waste incinerator facilities such as refuse incinerators are deteriorated or integrated for widening the area, and when peripheral equipment is renewed, etc.
It is necessary to dismantle the existing incinerator. At the time of this dismantling, the working environment will be significantly impaired by dioxins and heavy metals and other contaminants remaining in the incinerator. Notice on Prevention of Health Injury by Dioxins in Dismantling of Incineration Plants " In order to prevent dust generation during the decontamination work at the time of dismantling the incineration facility, this Circular requires that, for example, washing with high-pressure water to remove deposits in the incinerator equipment as follows. "Decontamination of demolition equipment Before demolition, decontaminate the target equipment by the following method. For places where the target part can be confirmed, such as inside the furnace wall and inside the equipment, decontaminate by high-pressure water washing. For confined areas such as flue, remove the flanges by hand and then remove the contamination by washing with high-pressure water. "

Conventionally, the removal of contaminants using high-pressure water in the dismantling work of waste incineration facilities has not yet been carried out in earnest, but according to the notification of the Ministry of Labor, cleaning with this high-pressure water is indispensable in the future. Become.

[0008] Tap water or industrial water is generally used as the washing water for the high-pressure water washing. In addition, the washing wastewater generated by washing is usually discharged according to the drainage standard of the area and the discharge standard such as sewerage.

[0009]

The amount of washing water used for the above high-pressure water washing varies depending on the scale of the waste incinerator equipment and the state of contamination, but it is expected that a large amount of washing water will be required. . Therefore, in order to reduce the amount of makeup water such as tap water and to greatly reduce the amount of water discharged to sewers, it is desired that the washing wastewater be treated to a reusable water quality and then reused as washing water.

When the waste incinerator facilities are classified according to the parts to be removed by the high-pressure water washing, incinerators, waste heat boilers,
Flues, gas cooling devices, dust collectors, chimneys, ash pits, wastewater treatment pits, etc.The contaminants are removed from the furnace facilities and pits, such as dust adhering to these parts of the furnace equipment. And soot, incineration ash, boiler dust, and sludge that remain and accumulate.

Therefore, the washing wastewater generated by high-pressure water washing contains these contaminants separated and removed by high-pressure water, and a large amount of complex substances set in landfill standards, wastewater standards, and the like. The standard water quality is as shown in Table 1. The contaminants in this washing wastewater are p
The solubility varies depending on the quality of the waste water such as H, ionic strength and oil content. On the other hand, the use of high-pressure water as washing water requires the following, so when collecting and reusing washing wastewater, a series of water treatment systems must meet the following requirements. It is necessary to obtain recycled water.

(1) In order to prevent clogging of the high pressure water washer pump, the concentration of suspended solids is kept low. (2) Reduce dioxin and heavy metal concentrations sufficiently. The working atmosphere at the time of high pressure water washing becomes high temperature due to frictional heat caused by contact between high pressure water and contaminants, and the reused water component is vaporized and volatilized in the air. During dismantling, the entire workplace is isolated.In this isolated workplace, during high-pressure water washing work, respiratory protection such as an air line mask will be installed.However, dioxins and heavy metals will be circulated in the workplace system by circulating water. Hazardous substances such as should not tend to concentrate in the working system. (3) After dismantling, reduce the amount of salt deposits remaining on the surface of the discharged waste, and keep the salt concentration low to prevent corrosion problems in the equipment used. (4) Sewage discharge standards or drainage standards must be satisfied so that water can be drained out of the water treatment system for reuse.

Furthermore, the amount of washing water used in high-pressure water washing varies greatly with time, and the components and concentrations of contaminants also vary greatly depending on the place of occurrence. It is desirable to be able to sufficiently cope with fluctuations.

However, the high pressure water cleaning itself at the time of dismantling of the waste incinerator facilities is not in full swing at present, and the water treatment system for the cleaning wastewater generated by the high pressure water cleaning is also described above. There is no system that sufficiently satisfies such requirements.

Accordingly, the present invention provides a method for efficiently treating and reusing washing wastewater generated when high-pressure water is used to remove contaminants adhering to incinerator facilities when dismantling waste incinerator facilities and the like. It is an object of the present invention to provide a method for cleaning incinerator facilities.

[0016]

According to a first aspect of the present invention, there is provided a method for cleaning waste incinerator equipment, comprising the steps of: A treatment step of detoxifying the slurry discharged from the step, a water separation step of separating water from a treatment product flowing out of the treatment step, and the water separated in the water separation step as high-pressure water in the stripping step. And feeding to the peeling step.

According to this method, the washing wastewater (slurry) generated in high-pressure water washing can be recovered and made harmless, and the treated water can be separated and reused for high-pressure water washing.

As this detoxification step, it is preferable to carry out a heavy metal insolubilization step and a dioxin adsorption step.

According to a third aspect of the present invention, there is provided a method for cleaning waste incinerator equipment, comprising: a separating step of spraying high-pressure water onto the attached matter in the waste incinerator equipment to separate the attached matter; and a slurry discharged from the separating step. A detoxification treatment step, a water separation step of separating water from a treatment product flowing out of the treatment step, and feeding the water separated in the water separation step to the separation step as high-pressure water in the separation step. And a detoxification treatment step comprising: adding a dithiocarbamic acid-based chelating agent to the slurry and selecting one or two selected from the group consisting of lead, cadmium and mercury. A first reaction step of insolubilizing at least one kind of metal, a second reaction step of adding powdered activated carbon to the effluent of the first reaction step to adsorb dioxins, and an iron salt being added to the effluent of the second reaction step. Add chromium, A third reaction step for insolubilizing one or more metals selected from the group consisting of ren and arsenic, and agglomeration in which an inorganic coagulant and an organic coagulant are added to the effluent of the third reaction step to perform coagulation And a reaction step.

According to this method, contaminants such as heavy metals and dioxins contained in the washing waste water and suspended substances are efficiently removed to obtain a treated water of reusable water quality.
This can be reused for high-pressure water washing.

In other words, the present inventors added the necessary items to the wastewater standard items as the water quality of the reused water satisfying the requirements (1) to (4) described above, and Water quality standards were set.

[0022]

[Table 2]

According to the third aspect of the present invention, the heavy metals and dioxins are sequentially insolubilized in the first to third reaction steps, and the insolubilized substances are coagulated and separated in the coagulation reaction step. Good reuse water satisfying the above water quality items can be obtained.

Further, according to this method, it is possible to sufficiently cope with fluctuations in water quality and water amount through a multi-step reaction process.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of a method for cleaning waste incinerator equipment of the present invention.

In the present invention, first, slurry-like cleaning wastewater containing exfoliated matter, which is generated in high-pressure water washing for spraying high-pressure water onto contaminants adhering to the waste incinerator facility and exfoliating the contaminated matter, is used as the raw material. After being received in the water tank 1, it is sent to the first reaction tank 2, and a dithiocarbamic acid-based chelating agent is added to the first reaction tank 2 to mainly lead (Pb) and cadmium (C).
d) Insoluble treatment of divalent heavy metals such as mercury (Hg).

The addition amount of the dithiocarbamic acid-based chelating agent in the first reaction tank 2 is appropriately determined according to the concentration of the heavy metal in the cleaning wastewater to be treated.
It is about 100 mg / L. The first reaction tank 2
Is a tank for insolubilizing divalent heavy metals such as Pb, Cd, and Hg. As an additive agent, a dithiocarbamic acid-based chelating agent is optimal, but not limited to a dithiocarbamic acid-based chelating agent. Sulfides, silicates, phosphates, carbonates and the like having the insolubilizing ability of the above.

The reaction solution in the first reaction tank 2 is
An adsorbent such as activated carbon, lignite, coke, or zeolite, preferably powdered activated carbon, is added to the reaction tank 3 to adsorb and remove dioxins dissolved in the liquid. There is no particular limitation on the powdered activated carbon added here, but those having an average particle diameter of 10 to 40 μm, particularly about 15 to 35 μm, in terms of handleability, adsorptivity, especially sedimentation in the subsequent coagulation sedimentation tank 6, etc. preferable. The amount of the powdered activated carbon to be added is appropriately determined according to the concentration of dioxins in the treated wastewater, but is generally about 10 to 150 mg / L.

The second reaction tank 3 is a tank for the purpose of adsorbing dioxins.
Powdered activated carbon is optimal, but not limited to powdered activated carbon, and a silicate-based adsorbent such as zeolite or another carbon-based adsorbent may be used.

The effluent of the second reaction tank 3 is then fed to a third reaction tank 4 to which an iron salt, preferably a ferrous salt is added.
Chromium (C) by reduction with ferrous salt and co-precipitation with coexisting calcium, aluminum and iron salt hydroxides
r ⁶⁺ ), selenium (Se), arsenic (As) and the like are insolubilized. As the ferrous salt, ferrous sulfate (FeSO
₄ ), ferrous chloride (FeCl ₂ ) and the like are preferable, and the amount of addition thereof is appropriately determined according to the concentration of heavy metals such as Cr ⁶⁺ in the cleaning wastewater to be treated.
It is about L. The pH of the third reaction tank 4 is pH 7-1.
Preferred 2.5 Of particular pH8.5~9.5 for insolubilization, but arsenic, selenium, the reduction of such ^{Cr 6+} is pH
If these concentrations are high, the pH is lowered once by adding an acid such as hydrochloric acid, and then an alkali is added.

The effluent from the third reaction tank 4 is then fed to a neutralization and coagulation reaction tank 5 where an inorganic coagulant and an organic coagulant are added to perform coagulation treatment. Examples of the added inorganic coagulant include polyaluminum chloride and aluminum sulfate. Examples of the organic coagulant include a partially hydrolyzed polyacrylamide, an acrylamide / acrylic acid copolymer, and acrylamide / acrylic acid-2-acid. Anionic organic coagulants such as acrylamide-2-methylpropanesulfonic acid copolymer, carboxymethylcellulose and sodium alkinate, and nonionic organic coagulants such as polyacrylamide are exemplified. The addition amount of the inorganic flocculant and the organic flocculant depends on the amount of the insolubilized substance in the influent water, but generally, the inorganic flocculant is 50 to 500 mg / L and the organic flocculant is 0.5 to
It is preferable to add about 5 mg / L.

In the neutralization-aggregation reaction tank 5, it is preferable to adjust the pH conditions to satisfy the discharge standard. However, the alkaline condition is less acidic than the acidic condition, and the elution of heavy metals is smaller. Sodium hydroxide (NaO
It is preferable to adjust the pH to a weak alkalinity of 7.5 to 8.5 by adding an alkali such as H).

The effluent from the neutralization and coagulation reaction tank 5 is then fed to a coagulation and sedimentation tank 6 for solid-liquid separation. After the separated sludge is fed to the sludge tank 7, the sludge is dewatered by a dehydrator 8 such as a filter press. Since the resulting dehydrated cake contains dioxins and heavy metals adsorbed on activated carbon, it is transferred to a management-type treatment plant after confirming that the standards are satisfied by the dissolution test and the like of the Environment Agency Notification No. 13. dispose.

The dehydrated filtrate obtained by this dehydration treatment is received in the filtrate tank 9 and is sent to the raw water tank 1 to be reprocessed together with the washing and drainage.

On the other hand, the separated liquid (supernatant water) in the coagulating sedimentation tank 6
Is fed to the filter 11 through the intermediate tank 10, and the SS that has flowed out in the flocculation settling tank 6 is further removed. This filter 1
As 1, a simple filter filled with a filter material having an adsorption function such as sand, granular styrofoam filter material, granular activated carbon, etc. may be used.
The concentrate containing SS is returned to the raw water tank 1 and reprocessed together with the washing wastewater.

The filtered water obtained by the filter 11 is one from which heavy metals and dioxins have been removed and SS has been removed to a high degree. As described above, the washing water of the high-pressure water washing contains salts. If they are removed, problems such as residual salts and corrosion will occur. Therefore, desalination is performed by a desalination device 12 such as a reverse osmosis membrane (RO) separator or an evaporator.

The treated water of the desalination unit 12 is sent to the high-pressure water washing step via the treated water tank 13 and reused as washing water. If the treated water amount is larger than the required amount of washing water, It is discharged as appropriate or returned to the filter 11 in some cases for reuse.

According to the method shown in FIG. 1, heavy metals, dioxins, SS, and salts in the washing wastewater are highly removed to obtain treated water of good quality suitable as washing water for high-pressure water washing. be able to.

Further, by providing a multistage reaction tank for removing contaminants and providing a raw water tank, an intermediate tank, and a treated water tank, it is possible to sufficiently cope with fluctuations in water quality and water amount.

In particular, by ensuring the residence time of each tank as follows, it is possible to sufficiently cope with a large fluctuation in the water load. Raw water tank residence time: 90 to 120 minutes First reaction tank residence time: 5 minutes or more, 10 to 30 minutes Second reaction tank residence time: 5 minutes or more, 30 to 120 minutes Third reaction tank residence time: 5 minutes or more, 10 to 30 minutes Neutralization / aggregation reaction tank residence time: 5 minutes or more, 10 to 30 minutes Intermediate tank residence time: 30 minutes or more, 30 to 60 minutes Treatment water tank residence time: 120 minutes or more

[0042]

The present invention will be described more specifically with reference to the following examples.

Example 1 According to the method shown in FIG. 1, the cleaning wastewater having the water quality shown in Table 4 discharged by high-pressure water cleaning in a refuse incinerator was treated at a treatment amount of 15 m ³ / hr.

The chemicals used were as follows, and the processing conditions and the like for each part were as shown in Table 3. Dithiocarbamic acid-based chelating agent Powdered activated carbon: average particle size 20 μm Inorganic coagulant: polyaluminum chloride Organic coagulant: partial hydrolyzate of polyacrylamide

[0045]

[Table 3]

The water separated from the flocculation and sedimentation tank received in the intermediate tank was filtered through a simple filter (Crytalite Filter (registered trademark) manufactured by Kurita Kogyo Co., Ltd.) and then desalted with an RO membrane separator.

On the other hand, the separated sludge in the coagulation sedimentation tank was dewatered by a filter press to obtain a dewatered cake. The dehydrated filtrate was circulated to a raw water tank together with the concentrated water of the simple filter to be treated.

As a result, the treated water having the water quality shown in Table 4 (all other water quality items satisfied the criteria in Table 2) was used at 14 L / water.
hr, and this treated water can be effectively reused as washing water for high-pressure water washing without causing clogging of pumps, corrosion problems of equipment, and problems of concentration of contaminants. Was.

The dewatered cake having a water content of 60% obtained by the filter press was disposed at a disposal site.

[0050]

[Table 4]

[0051]

As described in detail above, according to the method for cleaning waste incinerator equipment of the present invention, contaminants adhering to the incinerator equipment are removed with high-pressure water when dismantling the waste incinerator equipment or the like. The cleaning wastewater generated at the time can be efficiently treated and reused, and the supply water such as tap water used for high-pressure water cleaning can be saved, and the discharge water to the sewer can be significantly reduced. .

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of a method for cleaning waste incinerator equipment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw water tank 2 1st reaction tank 3 2nd reaction tank 4 3rd reaction tank 5 Neutralization coagulation reaction tank 6 Coagulation sedimentation tank 7 Sludge tank 8 Dehydrator 9 Filtrate tank 10 Intermediate tank 11 Filtration device 12 Desalination device 13 Treatment water tank

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI C02F 1/62 C02F 1/62 D EZ F23G 5/44 ZAB F23G 5/44 ZABZ F23J 1/00 F23J 1/00 Z 1 / 06 1/06 (72) Inventor Shunji Fukumoto 2-2-22 Kitahama, Chuo-ku, Osaka-shi, Osaka Inside Kurita Engineering Co., Ltd. (56) References JP-A-8-302250 (JP, A) JP-A-11- 104437 (JP, A) JP-A-10-34105 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B08B 3/00-7/04 C02F 1/00-1/62 F23G 5/44 F23J 1/00-1/06

Claims (3)

(57) [Claims] 1. A stripping step of spraying high-pressure water to deposits in a waste incinerator facility to strip the deposits, a treatment step of detoxifying a slurry discharged from the stripping step, Waste incineration, comprising: a water separation step of separating water from a treated material flowing out; and a step of feeding the water separated in the water separation step to the separation step as high-pressure water in the separation step. Furnace equipment cleaning method. 2. The method for cleaning waste incinerator equipment according to claim 1, wherein the detoxification treatment step includes a heavy metal insolubilization step and a dioxin adsorption step. 3. A stripping step of spraying high-pressure water to deposits in a waste incinerator facility to strip the deposits, a treatment step of detoxifying a slurry discharged from the stripping step, and A method for cleaning waste incinerator equipment, comprising: a water separation step of separating water from a processed material flowing out; and a step of feeding water separated in the water separation step to the separation step as high-pressure water in the separation step. In the detoxification step, a dithiocarbamic acid-based chelating agent is added to the slurry, and the slurry is selected from the group consisting of lead, cadmium, and mercury.
A first reaction step of insolubilizing one or more metals, a second reaction step of adding powdered activated carbon to the effluent of the first reaction step to adsorb dioxins, and an effluent of the second reaction step A third reaction step of adding an iron salt to the mixture to insolubilize one or more metals selected from the group consisting of chromium, selenium, and arsenic; and an inorganic flocculant and an organic flocculant in the effluent of the third reaction step. A coagulation reaction step of performing coagulation by adding an agent to the waste incinerator equipment.