JPH1157786A - Treatment of waste liquor from incinerator scrubber and equipment therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove harmful substances in waste liquor discharged from an incinerator scrubber for scrubbing an exhaust gas from an incinerator with alkali and to reduce the storage amount of the waste liquor recovering and reusing the alkali. SOLUTION: In this equipment, suspended matter, COD components, fluorine components and radioactive nuclides are separated and removed as harmful substances from waste liquor discharged from an incinerator scrubber, then alkali is recovered from the resulting liquid waste to reuse the recovered alkali as a scrubbing liquor for the scrubber. At this time, the suspended matter consisting of heavy metals, etc., in the scrubber waste liquor is separated and removed with a first filter 4 and also, the COD components are subjected to electrolysis with a COD decomposition device 11 and further, the fluorine components are removed by allowing fluorine ions of the fluorine components to react with calcium chloride in a fluorine removal device 5 to form a precipitate and thereafter, separating and removing the precipitate with a second filter 7. After removing these harmful substances, the resulting waste liquor is subjected to electrodialysis with an alkali recovery device 12 to recover alkali. When the concn. of alkali reaches a prescribed value, the recovered alkali is reused as a scrubbing liquid for the scrubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment system for an incinerator scrubber used in a nuclear facility, and more particularly to a method for treating wastewater from an incinerator scrubber capable of removing harmful substances and radionuclides contained in the waste scrubber. And its device.

[0002]

2. Description of the Related Art Waste liquid from an incinerator scrubber is generated as a waste liquid having a high NaCl (salt) concentration when hydrogen chloride and chlorine gas generated when vinyl chloride is incinerated are treated with an alkali absorbing liquid.

FIG. 11 shows a schematic system diagram of an incinerator 22 and a scrubber 24. In FIG. 11, reference numeral 23 denotes an exhaust gas introduction pipe for supplying exhaust gas from the incinerator 22 into the scrubber 24, and reference numeral 25 denotes a scrubber.
A cleaning liquid circulation pipe for circulating the cleaning liquid in 24, a circulation pump 26, an exhaust gas introduction pipe 27, a scrubber exhaust gas pump 28, a scrubber waste liquid outflow pipe 29 for discharging the scrubber waste liquid in the scrubber 24, and 30 a scrubber discharged. It is a waste liquid.

[0004] The scrubber 24 is used to neutralize acidic gas (HCl (hydrogen chloride gas) generated when vinyl chloride is incinerated) generated when papers and plastics are burned in the incinerator 22. Is provided. That is, NaOH (sodium hydroxide) is generally used as a scrubber cleaning solution, and NaCl is generated by a reaction with HCl. HCl + NaOH → NaCl + H ₂ O

[0005] When burning plastics, various kinds of pyrolysis products are mixed in the exhaust gas, and some of them are dissolved in the scrubber cleaning solution. Organic compounds having high volatility and those having weak affinity for water do not remain in the scrubber but flow into the air as exhaust gas.

Therefore, the inside of the scrubber 24 is initially filled with a NaOH solution, but by continuing incineration, the concentration of NaOH is reduced as shown in FIG.
Finally, the NaCl concentration will increase. At the same time, some of the thermal decomposition products generated during combustion as impurities are dissolved in the scrubber liquid, and the COD concentration increases.

[0007] The COD concentration does not become a constant value because it varies depending on the type of burnable material, the temperature of the incinerator, and the like. It is not possible to specify how much fluorine components and radionuclides migrate into the scrubber solution.
It is estimated that the COD, SS concentration, and fluorine concentration fall within the ranges shown in Table 1.

[0008]

[Table 1]

[0009]

The exhaust gas contains a small amount of organic components (COD components) and radionuclides in addition to hydrogen chloride and chlorine gas. Conventionally, scrubber waste liquid is N
Recycling was performed until the aCl concentration increased, and finally stored in the state of waste liquid (NaCl) or in the state of salt powder through a dryer.

Usually, the scrubber waste liquid is stored in a liquid state or a powder state. For this reason, the amount of storage has increased over time and the expansion of waste tanks and waste storage has become common.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and removes harmful substances and radionuclides contained in a scrubber effluent, and further recovers an alkali component from the scrubber effluent to reuse it in the scrubber. It is an object of the present invention to provide a wastewater treatment system for incinerator scrubbers, which makes it possible to significantly reduce wastewater generation.

[0012]

According to the first aspect of the present invention, an acidic exhaust gas generated when papers and plastics are incinerated in an incinerator is neutralized and washed in a scrubber with a washing liquid containing an alkali. Among the harmful substances contained in the scrubber waste liquid after washing, suspensions such as metals are separated and removed by filtration,
The COD component is electrolyzed, and the fluoride ions are further reacted with calcium chloride to precipitate the precipitate. The precipitate is filtered and the harmful substances are removed. Then, the alkali is recovered by electrolytic dialysis and reused as a washing solution for the scrubber. It is characterized by doing.

According to the first aspect of the present invention, in a scrubber using an alkaline solution provided for treating harmful substances in a gas discharged from an incinerator, harmful substances contained in a scrubber waste liquid discharged from the scrubber In addition, the radionuclide is removed, and the alkali component is recovered from the waste liquid of the scrubber to enable reuse in the scrubber.
In addition, harmful substances and radionuclides contained in the scrubber waste liquid can be selectively removed.Also, since the alkali component is recovered from the scrubber waste liquid and reused in the scrubber, the amount of waste liquid to be stored and powder The amount can be greatly reduced.

According to a second aspect of the present invention, there is provided a collection tank for collecting scrubber waste liquid obtained by washing exhaust gas from an incinerator with a scrubber, a first filter connected downstream of the collection tank, and a first filter. A fluorine removing device connected to the filtrate outlet side of the filter, a chlorine gas absorbing device for supplying chlorine gas to the fluorine removing device, a second filter connected downstream of the fluorine removing device, A COD decomposition device supply tank connected to the filtrate outlet side of the filter, a COD decomposition device connected downstream of the COD decomposition device supply tank, and an alkali recovery device connected downstream of the COD decomposition device. An alkali recovery tank connected to the downstream side of the alkali recovery device is provided.

[0015] The invention of claim 2 considers a solution or powder containing no harmful substance as a final storage form of the scrubber waste liquid.
Remove suspended material.

According to the second aspect of the present invention, since a filter is provided to remove the suspended matter in the scrubber waste liquid, this operation not only removes the suspended matter, but also removes the suspended matter in the COD decomposer and the alkali in the latter stage of the system. It is possible to suppress the performance degradation of the recovery device.

According to a third aspect of the present invention, the first filter comprises a backwashable hollow fiber membrane filter in which a large number of hollow fiber membranes are incorporated in a filter main body. The method is characterized in that suspended substances are removed.

According to the third aspect of the present invention, by using a back-flushable hollow fiber membrane filter for removing suspended substances, it is possible to perform a treatment with excellent filtration accuracy, and since the back-flush can be performed, the length can be increased. Operation during the period is enabled.

According to a fourth aspect of the present invention, the COD decomposing apparatus comprises an electrolysis tank in which a Ti / Pt electrode or the like is incorporated and a DC voltage is applied, and among the harmful substances in the scrubber waste liquid, COD (chemical oxygen demand) is used. Amount).

According to the fourth aspect of the present invention, the hypochlorous acid having a strong oxidizing power for generating an organic component mainly containing aldehydes and the like contained in the exhaust gas near the anode of the COD decomposition apparatus (electrolysis apparatus). Decomposition with ions becomes possible. Further, it becomes possible to lower the concentration of trace organic substances, which are COD components, in the scrubber waste liquid to a sufficiently low concentration by the action of hypochlorite ions generated by electrolysis.

[0021] The invention of claim 5 is characterized in that an alkali recovery device is provided for recovering alkali (NaOH) from the processing solution of the COD decomposition device. According to the invention of claim 5, it is possible to recover the alkali from the scrubber waste liquid (a waste liquid having a high NaCl concentration), and there is a merit that the collected alkali can be reused as the scrubber liquid. As an alkali recovery apparatus, a two-chamber electrodialysis apparatus using a cation exchange membrane as a diaphragm is provided. That is, the scrubber waste liquid (NaC
Na ions in the (l-rich waste liquid) are attracted to the cathode side via the cation exchange membrane, so that the concentration of sodium hydroxide in the cathode chamber can be increased.

According to a sixth aspect of the present invention, there is provided an alkali recovery tank connected to the cathode chamber for concentrating sodium hydroxide recovered in the cathode chamber of the alkali recovery apparatus to a certain concentration. Is provided with a recycling line. According to the invention of claim 6, sodium hydroxide can be concentrated to a concentration required for the scrubber solution.

According to a seventh aspect of the present invention, there is provided a recycling line for guiding the processing solution of the COD decomposition apparatus to the anode chamber side of the alkali recovery apparatus, and further recycling the liquid processed in the anode chamber of the alkali recovery apparatus to the inlet of the COD decomposition apparatus. It is characterized by being provided.

According to the seventh aspect of the present invention, by operating the alkali recovery device after the COD decomposition rate is sufficiently increased by the recycling process, organic matter contamination on the surface of the membrane (ion exchange membrane) of the alkali recovery device is reduced. Can be prevented.

The invention according to claim 8 is a method for absorbing chlorine gas discharged during operation of a COD decomposer and an alkali recovery device, wherein the chlorine gas outlet side of the COD decomposer or the alkali recovery device is connected to the fluorine gas. A chlorine gas absorbing device is provided between the removing device and the removing device.

According to the eighth aspect of the present invention, it is possible to efficiently absorb chlorine gas generated at the anode of the COD decomposition apparatus and the alkali recovery apparatus, and to use the absorbing solution for removing the fluorine component.

According to a ninth aspect of the present invention, in order to use calcium hydroxide as the chlorine gas absorbent, a calcium hydroxide solution is housed in the chlorine gas absorbing device. According to the ninth aspect of the invention, chlorine gas can be efficiently collected, and the generated calcium chloride can be used as a fluorine component remover.

[0028] The invention of claim 10 considers a solution or powder containing no harmful substance as the final storage form of the scrubber waste liquid.
It is characterized by having a fluorine removing device for removing a fluorine component.

According to the tenth aspect of the present invention, of the harmful substances in the scrubber waste liquid, the fluorine component can be efficiently removed by the fluorine removing device. Calcium chloride generated by a chlorine gas absorber is used to remove fluorine components. As a result, calcium chloride generated when the chlorine gas generated at the anode of the COD decomposition device and the alkali recovery device is absorbed into the calcium hydroxide solution is introduced into the fluorine removal device, whereby the fluorine component in the waste liquid is precipitated by calcium fluoride. (Removed from waste liquid)
Becomes possible.

An eleventh aspect of the present invention is characterized in that the second filter is provided with a filter for solid-liquid separation of a precipitate generated in the process of removing the fluorine component. According to the invention of claim 11, it is possible to efficiently separate the calcium fluoride precipitate by using the filter.

According to a twelfth aspect of the present invention, an electrode of a COD decomposer is used to remove radionuclides among the harmful substances in the scrubber waste liquid. Or a bypass line is provided between the downstream side of the first filter and the downstream side of the second filter, and the downstream side of the bypass line is
It is characterized in that it is connected to the inlet side of the D decomposition device.

According to the twelfth aspect of the present invention, the radioactive nuclide can be collected (electrodeposited) on the electrode surface irrespective of the type of charge (+ or-), and the radioactive concentration of the scrubber waste liquid can be reduced. .

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an incinerator scrubber waste liquid treatment method and apparatus according to the present invention will be described with reference to FIGS. The incinerator scrubber waste liquid treatment method of the present embodiment converts the scrubber waste liquid described in FIGS. 11 and 12 from the scrubber waste liquid (= NaCl) to sodium hydroxide (NCl) by an electrochemical process.
aOH) is recovered and used again as a scrubber solution (washing solution).

That is, according to the first aspect of the present invention, acidic exhaust gas generated when papers and plastics are incinerated in an incinerator is neutralized and washed in a scrubber with a washing liquid containing an alkali. Among the harmful substances contained in the scrubber waste liquid, suspended substances such as metals are separated and removed by filtration, the COD component is electrolyzed, and fluoride ions are further reacted with calcium chloride to precipitate, and the precipitate is filtered, An incinerator scrubber waste liquid treatment method, wherein after removing the harmful substance, the alkali is recovered by electrolytic dialysis and reused as a washing liquid for the scrubber.

In order to recover NaOH from the NaCl solution, a two-chamber electrodialysis device is used as an alkali recovery device. Since the ion exchange membrane used in this electrodialysis apparatus is susceptible to solid matter (SS) and organic contamination (≒ COD), it is necessary to filter in advance and further decompose the organic matter.

Therefore, in this embodiment, as shown in FIG. 1, a first filter 4 is provided via a pump 3 on the downstream side of a collection tank 2 for collecting the scrubber waste liquid flowing from the scrubber waste liquid inflow line 1. A COD decomposer 12 is provided in front of the alkali recovery device 12.

Here, by using a hollow fiber membrane filter as the first filter 4, even if the inlet concentration is several thousand mg / l, the treatment liquid can be reduced to 0.1 mg / l or less. COD
The decomposition device 11 generates a substance having an oxidizing power (hypochlorous acid) by applying a DC voltage, and C
Even if the OD is about 1000 mg / l, it has the ability to reduce it to 10 mg / l or less. That is, by combining the first filter 4 and the COD decomposing device 11, the load on the cation exchange membrane of the alkali recovery device (electrolysis device) 12 is greatly reduced.

According to the invention of claim 2, as shown in FIG. 1, a collection tank 2 for collecting scrubber waste liquid obtained by washing exhaust gas from an incinerator with a scrubber, and a pump 3 downstream of the collection tank 2 are provided. Connected first filter 4
A fluorine removing device 5 connected to the filtrate outlet side of the first filter 4; a chlorine gas absorbing device 15 for supplying chlorine gas to the fluorine removing device 5 via a pump 16; 5 connected via a pump 6 to the downstream side of
, A COD decomposer supply tank 8 connected to the filtrate outlet side of the second filter 7, and a C connected via a pump 10 to the downstream side of the COD decomposer supply tank 8.
An OD decomposition device 11, an alkali recovery device 12 connected downstream of the COD decomposition device 11, and an alkali recovery device 12;
An incinerator scrubber waste liquid treatment apparatus, comprising: an alkali recovery tank connected via a recycling line 19 downstream of the incinerator.

In FIG. 1, reference numeral 1 denotes a scrubber waste liquid inflow line, which is a pipe flow path through which a waste liquid containing NaCl rich and containing harmful substances flows. Reference numeral 2 denotes a collection tank for storing the liquid to be treated from the scrubber waste liquid inflow line. Collection tank 2
The scrubber waste liquid collected in the above is sent to the first filter 4 by the pump 3 to remove suspended matter in the scrubber waste liquid. The waste liquid treated by the first filter 4 is collected in the fluorine removing device 5.

In the fluorine removing device 5, calcium chloride generated by the chlorine gas absorbing device 15 is supplied through a pump 16 in accordance with the level of fluorine concentration to precipitate fluorine ions present in the scrubber waste liquid. The sediment flows into the second filter 7 from the pump 6, is separated by the filter 7, and is collected in the COD decomposition device supply tank 8.

Since the scrubber waste liquid does not always contain fluorine ions (generated when a fluororesin is incinerated), if the fluorine ions are not contained, the first ion is used.
Is collected in the COD decomposition device supply tank 8 via a bypass line 9 connected between the filter 4 and the COD decomposition device supply tank 8. The waste liquid collected in the COD decomposition device supply tank 8 is sent to the COD decomposition device 11 by the pump 10.

As shown in FIG. 3, the COD decomposer 11 incorporates a Ti / Pt electrode having excellent corrosion resistance, etc., and has a function of applying a DC voltage to both electrodes to decompose the COD component in the waste liquid. Consists of That is, hypochlorite ions generated near the anode attack and decompose organic components (aldehydes), which are the main components of COD. This C
The OD decomposition apparatus 11 has a function of electrodepositing heavy metal ions or ionized radionuclides in the waste liquid on the electrode, in addition to the function of decomposing COD.

In a waste solution having a high NaCl concentration such as a scrubber waste solution, chlorine gas is generated along with the electrolytic reaction.
The chlorine gas is sent to the chlorine gas absorber 15 through the pipe 14,
Absorb in a calcium hydroxide solution as an absorbing solution. The gas processed by the chlorine gas absorbing device 15 is sucked by a pump and sent to an exhaust gas system.

The scrubber waste liquid treated by the COD decomposition device 11 enters the anode chamber 12a of the alkali recovery device 12, and the Na ions in the scrubber waste liquid are attracted to the anode 12b and move as shown in FIG. A cation exchange membrane 12d is provided between the anode chamber 12a and the cathode chamber 12c. Na ions are separated by the cation exchange membrane 12d, but Na ions (Na ⁺ ) have a positive charge. Therefore, it is possible to pass through the cation exchange membrane 12d. Reference numeral 12e indicates a cathode.

The cathode chamber 12c of the hydroxide ion (OH ^-) are attracted to the anode 12b Conversely, sodium hydroxide concentration in the cathode chamber 12c can not transmit cation exchange membrane 12d is increased in the course of processing time. The scrubber waste liquid treated in the anode chamber 12a flows into the COD decomposition apparatus supply tank 8 through the recycle line 13 connecting the anode chamber 12a of the alkali recovery apparatus 12 and the COD decomposition apparatus supply tank 8 until the COD concentration is sufficiently reduced. And then recycled and processed.
As in the case of the COD decomposer 11, chlorine gas is generated at the anode due to the electrolytic reaction. However, as in the case of the COD decomposer 11, the chlorine gas is led to the chlorine gas adsorber 15 through the chlorine gas flow pipe 14, whereby chlorine is removed. .

In the cathode chamber of the alkali recovery apparatus 12, sodium hydroxide is concentrated by the pump 18 through the alkali recovery tank 17. When fully concentrated, pump 20
Is returned to the incinerator scrubber and reused as a cleaning liquid.

FIG. 2 shows the first to third embodiments for removing suspended substances (SS) among the harmful substances in the scrubber waste liquid.
3 shows changes in the inlet concentration and the outlet concentration when the filter 4 is used. Scrubber effluents may corrode piping materials (carbon steel, stainless steel) due to high salt concentration and produce suspended matter. However, installing a filter efficiently removes corrosion products (suspended matter). Can be removed. By removing the suspended solids (SS), it is possible to suppress a decrease in performance in the subsequent stages of the fluorine removing device 5, the COD decomposing device 11, and the alkali recovering device 12.

FIG. 3 shows a COD decomposing apparatus 11 according to the fourth embodiment.
Schematically shows the structure of The COD decomposer 11 is an electrolytic cell to which a DC voltage is applied, and a scrubber waste liquid (NaCl)
Produces hypochlorite ions at the anode. Since this hypochlorite ion has an excellent ability to decompose organic substances, it can efficiently decompose COD components (= mainly organic components).

The COD decomposer 11 also causes electrodeposition of heavy metal ions and ionized radionuclides on the anode or cathode surface (precipitation on the electrode surface by the same reaction as plating). FIG. 4 shows the change in the processing time and the COD concentration in the COD decomposition apparatus 11 in FIG. With processing,
A reduction in COD was observed.

FIG. 5 shows the structure of the alkali recovery unit 12 for recovering alkali from the treatment liquid of the COD decomposition unit 11 according to claims 5 to 7. The alkali recovery device 12 is a two-chamber electrolytic dialysis tank provided with a cation exchange membrane as a diaphragm. The alkali recovery unit 12 applies N.C.
The a ions and the like move to the cathode chamber, and the alkali concentration in the cathode chamber can be increased.

In the COD decomposer 11, C contained in the scrubber waste liquid is removed.
After recycling and sufficiently decomposing the OD component, the alkali recovery device 12 is turned on to recover the alkali. This alkali recovery device 12 is also provided with a recycling line on the cathode chamber side, and is concentrated until it can be reused by a scrubber. FIG. 6 shows the recovered alkali (N
FIG. 4 is a graph showing a change in aOH) concentration, and it is recognized that the NaOH concentration increases with time.

FIG. 7 shows an apparatus 15 for absorbing chlorine gas generated from the COD decomposition apparatus 11 and the alkali recovery apparatus 12 in the eighth and ninth aspects. As shown in FIG. 7, the chlorine gas absorbing device 15 is a suction device containing a calcium hydroxide solution, and draws in chlorine gas with a pump to change the chlorine gas into calcium chloride. The detoxified exhaust gas is sent to an exhaust gas treatment system, and the generated calcium chloride is supplied as a reactant for a fluorine removing device.

FIG. 8 shows a fluorine removing apparatus 5 used when a fluorine component is mixed in the scrubber waste liquid in the tenth aspect. Fluorine ions in the waste liquid react with calcium chloride (CaCl ₂ ) supplied from the chlorine gas absorbing device 15 to become hardly soluble calcium fluoride. That is,
In FIG. 8, a stirrer 21 is provided in the fluorine removing device 5, a calcium chloride solution is supplied from above the device 5, and the calcium chloride solution is sent from the bottom to the second filter via the pump 6.

FIG. 9 shows changes in the inlet concentration and the outlet concentration when the second filter 7 is used to separate the calcium fluoride precipitate generated by the fluorine removing device 5 in claim 11. Since the amount of calcium chloride added is changed according to the level of the fluorine concentration in the waste liquid, the amount of generated calcium fluoride also differs greatly. The precipitate formed in the fluorine removing device is separated by a filter, and the outlet concentration can be kept sufficiently low.

Next, a twelfth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. When the combustible material to which the radionuclide is attached is burned, the nuclide may be transferred to the exhaust gas and further dissolved in the scrubber waste liquid. The state of the ion and the type of charge of the radionuclide dissolved in the scrubber wastewater naturally differ depending on the nuclide.

In the present embodiment, an electrode of the COD decomposer 11, for example, a Ti / Pt electrode is used to remove radioactive nuclides among harmful substances in the scrubber waste liquid. Therefore, following the system shown in FIG.
The scrubber waste liquid containing a radionuclide flows into the collection tank 2 shown in FIG. 1 via a pump 3, or the outlet side of the first filter 4 connected to the collection tank 2 shown in FIG. Of the bypass line 9
Is connected to the outlet side of the second filter 7, that is, the downstream side, or directly to the inlet side of the COD decomposer 11.

Since the COD decomposer 11 and the electrolyzer of the alkali recovery unit 12 using a DC source are connected in series, the radionuclide from the scrubber waste liquid containing the radionuclide is efficiently applied to the electrode surface. Can be recovered.

FIG. 10 shows changes in the treatment time and the radioactivity concentration of the COD decomposer 11 when the radionuclide is contained in the scrubber waste liquid. Although Co-60 was added as a radionuclide to the scrubber waste liquid, it was recognized that the radioactivity concentration decreased as the COD concentration changed over the treatment time.

[0059]

According to the present invention, after separating and removing suspended substances, COD, fluorine components and radionuclides as harmful substances from incinerator scrubber waste liquid, alkali is recovered from the waste liquid and used as a scrubber cleaning liquid. Can be reused. For this reason, the storage amount in the state of a solution or powder can be significantly reduced as in the related art.

[Brief description of the drawings]

FIG. 1 is a system diagram for explaining a first embodiment of an incinerator scrubber waste liquid treatment method and apparatus according to the present invention.

FIG. 2 is a characteristic diagram showing changes in the concentration at the inlet and the outlet of the filter when the suspended matter (SS) is removed by the first filter among the harmful substances in the waste liquid of the scrubber in FIG.

FIG. 3 is a schematic cross-sectional view showing a COD decomposer for decomposing COD components in the scrubber waste liquid in FIG.

4 is a graph showing the relationship between the processing time of the COD decomposer in FIG.
FIG. 4 is a curve diagram showing a change in D density.

FIG. 5 is a schematic cross-sectional view showing an alkali recovery apparatus for recovering alkali from a treatment liquid of the COD decomposition apparatus in FIG.

FIG. 6 is a characteristic diagram showing changes in the processing time and the concentration of recovered alkali in the alkali recovery apparatus in FIG.

FIG. 7 is a schematic sectional view showing a chlorine gas absorbing device for absorbing chlorine gas generated from a COD decomposition device and an alkali recovery device in FIG.

FIG. 8 is a schematic cross-sectional view showing a fluorine removing apparatus used when a fluorine component is mixed into the scrubber waste liquid in FIG.

FIG. 9 is a diagram showing changes in the inlet concentration and the outlet concentration when a filter is used to separate the calcium fluoride precipitate generated by the fluorine removing device in FIG.

FIG. 10 is a curve diagram showing changes in treatment time and cobalt-60 radioactivity concentration in the COD decomposition apparatus in FIG.

FIG. 11 is a system diagram showing a scrubber waste liquid generation process from an incinerator for explaining a conventional example.

FIG. 12 is a curve diagram showing a change in concentration of a scrubber solution in the scrubber in FIG. 11;

[Explanation of symbols]

1 ... Scrubber waste liquid inflow line, 2 ... Collection tank, 3 ...
Pump, 4 ... filter, 5 ... fluorine removal device, 6 ... pump, 7 ... filter, 8 ... COD decomposition device supply tank, 9 ...
Bypass line, 10… pump, 11… COD decomposer, 12
... alkaline recovery equipment, 13 ... recycling line, 14 ... chlorine gas circulation pipe, 15 ... chlorine gas absorption equipment, 16 ... pump, 17
... alkali recovery tank, 18 ... pump, 19 ... recycling line, 20 ... pump, 21 ... stirrer, 22 ... incinerator, 23 ... exhaust gas introduction pipe, 24 ... scrubber, 25 ... cleaning liquid circulation pipe, 26
... Circulation pump, 27 ... Exhaust gas discharge pipe, 28 ... Scrubber exhaust gas pump, 29 ... Scrubber waste liquid outflow pipe, 30 ... Scrubber waste liquid.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01D 61/44 500 C02F 1/52 Z C02F 1/44 1/58 M 1/461 9/00 502M 1/469 502P 1/52 G21F 9/02 ZAB 1/58 521Z 9/00 502 9/06 ZAB 511A G21F 9/02 ZAB 521A 521 9/10 ZABF 9/06 ZAB C02F 1/46 101C 511 103 521 9/10 ZAB (72) Inventor Kenji Fujihata 1 Tokoba, Komukai Toshiba-cho, Kawasaki City, Kanagawa Prefecture

Claims (12)

[Claims] 1. An acidic exhaust gas generated when papers and plastics are incinerated in an incinerator, neutralized and washed in a scrubber with a washing liquid containing an alkali, and harmful substances contained in the scrubber waste liquid after the washing. Among them, suspensions such as metals are separated and removed by filtration, the COD component is electrolyzed, and fluoride ions are further reacted with calcium chloride to precipitate. After filtering this precipitate to remove the harmful substances, A method for treating wastewater from an incinerator scrubber, wherein the alkali is recovered by electrolytic dialysis and reused as a washing liquid for the scrubber. 2. A collection tank for collecting a scrubber waste liquid obtained by washing exhaust gas from an incinerator with a scrubber, a first filter connected downstream of the collection tank, and a filtrate outlet of the first filter. Removing device connected to the side, a chlorine gas absorbing device supplying chlorine gas to the fluorine removing device, a second filter connected downstream of the fluorine removing device, and a filter of the second filter. COD connected to the liquid outlet side
Decomposer supply tank, COD decomposer connected downstream of this COD decomposer supply tank, alkali recovery unit connected downstream of this COD decomposer, and alkali recovery connected downstream of this alkali recovery unit An incinerator scrubber waste liquid treatment device comprising a tank. 3. The incinerator scrubber waste liquid treatment apparatus according to claim 2, wherein said first filter comprises a backwashable hollow fiber membrane filter. 4. The incinerator scrubber waste liquid treatment apparatus according to claim 2, wherein said COD decomposition apparatus comprises an electrolysis tank. 5. The incinerator scrubber waste liquid treatment apparatus according to claim 2, wherein said alkali recovery apparatus comprises a two-chamber type electrodialysis apparatus using a cation exchange membrane as a diaphragm. 6. The incinerator scrubber according to claim 5, wherein a recycle line is provided in the cathode chamber for concentrating sodium hydroxide recovered in the cathode chamber of the alkali recovery apparatus to a certain concentration. Waste liquid treatment equipment. 7. A recycling line for introducing a treatment liquid of the COD decomposition apparatus to an anode chamber side of the alkali recovery apparatus and recycling a liquid passing through the anode chamber to an inlet of the COD decomposition apparatus. The incinerator scrubber waste liquid treatment apparatus according to claim 2. 8. An incinerator scrubber waste liquid treatment apparatus according to claim 2, further comprising a chlorine gas absorbing device for absorbing chlorine gas discharged as the COD decomposition device and the alkali recovery device are operated. . 9. The incinerator scrubber waste liquid treatment device according to claim 8, wherein a calcium hydroxide solution is stored in the chlorine gas absorption device. 10. The incinerator scrubber waste liquid treatment apparatus according to claim 2, wherein a supply line for calcium chloride generated by the chlorine gas absorption apparatus is provided in the fluorine removal apparatus. 11. The incinerator scrubber waste liquid treatment apparatus according to claim 2, further comprising a second filter for solid-liquid separation of a precipitate generated in a fluorine component removal process of said fluorine removal apparatus. . 12. The downstream side of the first filter and the second filter.
3. An incinerator scrubber waste liquid treatment apparatus according to claim 2, wherein a bypass line is provided between the filter and the downstream side of the filter, and the downstream side of the bypass line is connected to the inlet side of the COD decomposer. .