JP2002292363A - Method for treating dioxins in wastewater from waste disposer and disposer therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating dioxins(DXN) in wastewater from a waste disposer, whereby the discharged water will fulfie severer regulations on a dioxin concentration in future which, and the costs of an installation, a maintenance, an exchange, and an operation is reduced, and to provide the disposer therefor. SOLUTION: A DXN-containing wastewater disposer 20 is a combination of (i) a DXN-containing wastewater system M that collects DXN-containing wastewater arising from the bringing into contact with a product of waste incineration in each treatment step and from the washing of substances with which it is brought into contact, (ii) a water collection tank 28 that receives the collected wastewater, and (iii) a waste water return means N that returns the wastewater from the tank 28 to the waste incineration step. By means of a selector 35, the wastewater is returned to a waste pit 22 or an furnace incinerator 23 to be used in a incineration step or is returned to a temperature- lowering tower 25 to be treated in a cooling step and is detoxified in a waste gas treatment step. Alternatively, the wastewater is simultaneously returned to the pit 22, incinerator 23, and the tower 25 and is treated and detoxified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to wastewater discharged from waste treatment facilities such as stokers for treating industrial waste (combustibles) and general waste, fluidized beds, kilns, and other incineration facilities, and gasification and melting treatment facilities. And a method for treating dioxins.

[0002]

2. Description of the Related Art Conventionally, wastewater treatment processes in waste treatment facilities, that is, wastewater treatment generated in a combustion treatment process, a gas cooling treatment process, and an exhaust gas treatment process are generally treated by a coagulation sedimentation method.
The treated water is further processed by a sand filtration method.

FIG. 2 is a schematic diagram showing an example of a wastewater treatment facility for performing the above wastewater treatment. The wastewater treatment equipment 1 has a sand filtration tower 4 disposed via a coagulation sedimentation tank 2 and a neutralization tank 3 on the downstream side.

The objects of wastewater treatment are generally platform washing water, car washing drainage, ash melting facility drainage, pure water drainage, ash sewage tank drainage, and the like.

[0005] The platform washing water and the car wash drainage are sent to an organic drainage tank 5, where they are pumped to an organic control tank 6 by a pump P1 and are aerated in a biological treatment tank 7 through the organic control tank 6 and an inorganic drain tank 8 is provided. Sent to

On the other hand, each wastewater from the ash melting facility 9, the pure water apparatus 10, and the ash sewage tank 11 is sent to the inorganic drainage tank 8. The drain of the drain pit 12 provided in the garbage pit and the treated water of the sludge concentration tank 17 are also sent to the inorganic drain tank 8. P2 is a pump for pumping the drain to the inorganic drain tank 8 under pressure.

[0007] These wastewaters are supplied from an inorganic drainage tank 8 to a pump P.
3 to the inorganic adjustment tank 13 and the inorganic adjustment tank 1
After 3, a neutralization treatment with caustic soda is performed in a reaction tank 14, and a coagulation treatment with a coagulant is performed in a coagulation tank 15.

The wastewater subjected to the neutralization treatment and the coagulation treatment is sent to the coagulation sedimentation tank 2. After the waste water is stirred by the stirrer 16, the aggregated sludge is removed by the pump P 4 in the sludge concentration tank 17.
To be pumped. The sludge concentrated in the sludge concentration tank 17 is pumped to a garbage pit or the like.

On the other hand, the treated liquid from which the coagulated sludge is separated in the coagulation sedimentation tank 2 is sent to a filtration water tank 18, pumped to a sand filtration tower 4 by a pump P 5, passed through the sand filtration tower 4, and stored in a discharge tank. And discharged to the outside of the system as needed, or used for reuse.

Although the purpose of the wastewater treatment equipment 1 shown in FIG. 2 is to originally remove heavy metals and organic substances in wastewater, dioxins adsorbed on suspended substances are also removed.

As for the removal of dioxins, the wastewater treatment equipment 1 was reviewed as emission standards were determined by the Dioxins Special Treatment Law, and ultraviolet irradiation was performed as an advanced treatment device after the coagulation sedimentation tank and sand filtration tower. It is also proposed to install a facility for accelerated oxidation treatment using ozone, hydroxide ions and the like, and a membrane separation facility.

[0012]

The wastewater treatment equipment 1 according to FIG.
A high dioxin removal rate can be obtained by coagulation sedimentation and sand filtration. The effluents treated by the effluent treatment equipment 1 are platform washing water, car washing effluent, ash melting equipment effluent, pure water effluent, ash sewage and the like, as described above.

However, removal of dioxins by coagulation sedimentation and sand filtration has already reached its limit, and it is not possible to expect a further increase in the removal rate. Therefore, if stricter emission standards are set by tightening regulations, I can not cope. Of the wastewater handled by the wastewater treatment equipment mentioned above, platform washing water, car washing wastewater, ash melting equipment wastewater, and pure water equipment wastewater do not contain dioxins, so they are installed in the conventional coagulation sedimentation and sand filtration treatments, and installed in the subsequent stage. The advanced treatment used for dioxin removal equipment reduces the load due to the decrease in concentration due to dilution, while increasing the treatment amount.

On the other hand, a proposal to install an accelerated oxidation treatment facility having a UV irradiation, an oxygen and ozone supply facility, a circulation pump, etc., and a membrane separation facility at a stage subsequent to the coagulation sedimentation tank and the sand filtration tower is expected in the future. It is thought that it can respond to stricter water quality standards due to stricter regulations, but requires installation areas for accelerated oxidation treatment equipment and membrane separation equipment in addition to conventional wastewater treatment equipment, and requires the use of special equipment and equipment. Large burden of installation cost, maintenance and replacement cost, etc.

[0015] In particular, the accelerated oxidation treatment equipment is provided with ultraviolet irradiation,
Since the power consumption of oxygen, ozone supply equipment, circulation pumps, and the like is large, the burden of operating costs is also large.

The present invention has been made to solve the above-mentioned problems, and can secure the concentration of effluent water that can cope with the tightening of regulations in the future, and reduce the burden of installation costs, maintenance and replacement costs, operation costs, and the like. It is an object of the present invention to provide a method and an apparatus for treating dioxins in wastewater of a waste treatment facility.

[0017]

Means for Solving the Problems The present inventors have organized and examined the respective problems in order to solve the above-mentioned problems of the wastewater treatment equipment. First, the goal was to have a high decomposition / removal capacity for dioxins, or to prevent dioxin-containing wastewater from flowing into wastewater treatment equipment, and to use a small and inexpensive dioxin treatment device.
As a countermeasure, only the dioxin-containing wastewater will be an independent system. As a countermeasure against waste, separate drainage from objects that come into contact with main ash, fly ash, and exhaust gas will be used. As a result, the following invention has been achieved.

According to the first aspect of the present invention, when the waste is treated in a waste treatment process including a waste treatment process, a waste gas cooling process, and an exhaust gas treatment process by a waste treatment facility, the waste treatment is performed. Collecting dioxin-containing wastewater produced by contacting and / or washing the contacted object,
A method for treating dioxins in wastewater from a waste treatment facility, wherein the dioxin-containing wastewater is returned to the treatment step for treatment and detoxification.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, dioxin-containing wastewater is contained in waste and treated in a combustion treatment step, and detoxified in an exhaust gas treatment step.

According to a third aspect of the present invention, in the first or second aspect of the invention, dioxin-containing wastewater is sprayed into a furnace installed in the combustion treatment step and treated in the combustion treatment step. It is detoxified in an exhaust gas treatment process.

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, the dioxin-containing wastewater is returned to the temperature reducing tower provided in the cooling step and evaporated in the cooling step. And detoxification in the exhaust gas treatment process.

According to a fifth aspect of the present invention, there is provided a process for treating dioxins in waste water generated in a waste treatment process including a combustion treatment, a cooling treatment, and an exhaust gas treatment in a waste treatment facility having a waste supply means. An apparatus, comprising: a dioxin-containing wastewater system for collecting dioxin-containing wastewater generated in the waste treatment step; a water collecting tank for receiving the collected wastewater; and returning the wastewater from the water collection tank to the waste treatment step. An apparatus for treating dioxins in wastewater of a waste treatment facility, wherein the dioxin is disposed in combination with wastewater return means.

The invention according to claim 6 is characterized in that, in the invention according to claim 5, a wastewater return means for returning dioxin-containing wastewater to a waste supply facility is provided.

The invention according to claim 7 is characterized in that, in the invention according to claim 5 or 6, a waste water return means for returning dioxin-containing waste water to the inside of a furnace installed in the combustion treatment step is provided. I do.

The invention according to claim 8 is the invention according to claim 5, 6, or 7, further comprising a wastewater return means for returning the dioxin-containing wastewater to the cooling tower installed in the cooling process. It is characterized by the following.

The wastes to be treated in the present invention are general wastes such as garbage and industrial wastes due to combustibles. Waste treatment facilities for treating the wastes include stokers, fluidized beds, incineration facilities such as kilns, and gas. It includes a chemical fusion treatment facility and the like.

In general, waste treatment equipment has a supply means such as a hopper or a short supply for supplying waste to a refuse incinerator, for example. A garbage storage area (pits) for temporarily storing garbage is provided.

However, when the waste treatment equipment is small, the directly transported waste may be supplied to a hopper or the like without using a waste storage area (pit).
Claim 6 defines a waste supply means including a waste pit.

According to the present invention, by installing a water collecting tank for collecting and receiving dioxin-containing wastewater and a means for returning only dioxin-containing wastewater from the water collection tank to the waste treatment step, contact with waste incineration can be achieved. Then, only the dioxin-containing wastewater generated by washing and / or washing the contacted object is collected, returned to the above-mentioned treatment step, treated, and detoxified in the exhaust gas treatment step. Therefore, the dioxin-containing wastewater is treated in the waste treatment process as usual, and is rendered harmless in the exhaust gas treatment process.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a waste incineration facility will be described in detail with reference to the drawings as an example of an embodiment of a waste disposal facility according to the present invention. FIG. 1 is a schematic diagram showing an example of a refuse incinerator according to an embodiment of the present invention. The refuse incineration equipment 21 roughly divides the refuse incineration treatment process into a combustion treatment process, a gas cooling treatment process, and an exhaust gas treatment process, and shows typical examples of devices installed in each treatment process as described below.

A refuse pit 22 attached to a refuse input hopper, a combustion chamber provided with a grate and the like and an incinerator 23 provided with a boiler and the like are installed in the combustion processing step, and an economizer 24 and a temperature reducing apparatus are provided in the gas cooling processing step. A tower 25 is installed, and a dust collector 26 such as a bag filter and a chimney 27 are installed in the exhaust gas treatment process.

According to the above-described refuse incineration process, refuse is received by the refuse pit 22 and is then introduced into a refuse input hopper, where it is burned in the incinerator 23 and separated into combustion gas and main ash. The combustion gas is maintained at 800 ° C. or higher (preferably 850 ° C. or higher), is completely burned, and is discharged as exhaust gas in the next step. The exhaust gas is cooled to 200 ° C. or lower in an economizer 24 and a cooling tower 25 and is collected by a dust filter (bag filter) 2.
The exhaust gas that has been collected and purified in step 6 is released from the chimney 27 into the atmosphere via an induction ventilator.

In the present invention, the dioxin-containing wastewater treatment apparatus 20 includes a dioxin-containing wastewater system M that collects dioxin-containing wastewater generated by contacting and / or washing the incinerated material in each of the above-described treatment steps. , Receiving the collected dioxin-containing wastewater
And a waste water return means N for returning the waste water from the water collecting tank 28 to the refuse incineration treatment step.

The waste incineration is main ash, fly ash and exhaust gas.
The contacted object is installed in each process and the equipment that comes in contact with the garbage incineration material, the main ash in the process of processing the fly ash and loading it out of the system, the conveyor that comes in contact with the fly ash, the kneader, Targets include all processed bunkers and their installed floors. This is for collecting all dioxin-containing wastewater.

In the embodiment shown in FIG. 1, the dioxin-containing drainage system M (hereinafter referred to as DXN-containing drainage system M) is roughly classified into contact with main ash separated in the incinerator 23 and / or cleaning of the contacted objects. DXN-containing drainage system M1
DXN-containing drainage system M generated by contacting fly ash collected by M 2, economizer 24, cooling tower 25, and dust collector (bag filter) 26 and / or washing the contacted object
3, M4.

The main ash is generally supplied to the ash melting device 32 at 120
The slag is formed at 0 to 1600 ° C. to reduce the concentration and volume of dioxins. However, a part thereof is calmed down in the ash sedimentation tank 33, and the ash sediment is unloaded outside the system. The treated water (ash mud for convenience) in the ash sedimentation tank 33 is DXN
It is sent to the water collecting tank 28 in the contained drainage system M1. Further, DXN-containing washing water (referred to as floor washing water for convenience) generated when unloading the ash sediment from the ash sedimentation tank 33 is sent to the water collecting tank 28 in the DXN-containing drainage system M2.

On the other hand, after the fly ash is collected, the fly ash is sent to a fly ash treatment device 34 to reduce the volume and prevent the outflow of heavy metals contained therein for use in a landfill or the like. Melt solidification, cement solidification, chemical treatment, stabilization treatment with acids and other solvents and the like are performed.

At this time, the DX such as a conveyor, a kneader, a processed bunker, and a floor on which the conveyor is in contact with the fly ash.
The N-containing washing water (referred to as floor washing water for convenience) is sent to the water collecting tank 28 in the DXN-containing drainage systems M3 and M4.

Unlike the conventional ash wastewater tank, the water collecting tank 28 eliminates the drainage system from the water collecting tank 28 to the wastewater treatment facility adjacent to the refuse incineration facility, and receives the DXN-containing wastewater collected from the DXN-containing wastewater system M. This is a base from which DXN-containing wastewater is returned to the garbage incineration process. Also, as described above, DXN-containing wastewater is generated by contacting and / or cleaning objects in contact with garbage incineration, so that floor rinsing water of the main ash and fly ash treatment / export equipment and overflow of the floor sedimentation tank. It appears as water and the like, and has the property that the amount of generation greatly changes over time. Therefore, the water collecting tank 28 contributes to the stabilization of the processing step as a buffer tank absorbing the fluctuation of the flow rate. The number of the water collecting tanks 28 is not limited to one, and can be appropriately provided as needed. Therefore, the conventional ash sewage tank can be partially modified and used as the water collecting tank 28 of the present invention.

The drainage return means N for returning the wastewater from the water collecting tank 28 to the refuse incineration process comprises a drainage supply system 29, a supply device 30, and a blowing device 31.
, A pump P for the supply device 30, and a nozzle for the blowing device 31. The drainage return means N is provided with a switching device 35 in the drainage supply system 29, and as preferable examples, branch wastewater supply systems 29 a, 29 b, and 29 c are provided in the garbage pit 22, the incinerator 23, and the cooling tower 25.

The DXN-containing wastewater is returned to the garbage pit 22 by the switching device 35 and treated in the combustion treatment step, the DXN-containing wastewater is returned to the incinerator 23 and treated in the combustion treatment step, and the DXN-containing wastewater is returned to the cooling tower. It can be returned and evaporated in a cooling step, and detoxification can be performed in an exhaust gas treatment step. Further, they are combined with each other and, for example, DXN-containing wastewater is simultaneously returned to the garbage pit 22, the incinerator 23, and the temperature reducing tower 25 to incinerate the garbage. It can be treated in each processing step of the process, and can be rendered harmless in the exhaust gas treatment step.

In the embodiment shown in FIG. 1, a garbage incineration facility is taken up as an example of a waste treatment facility, and the garbage pit 22, the incinerator 23, and the cooling tower 25 have been described. However, the return destination is not limited to this. DXN-containing wastewater can be blown into a place where the DXN-containing wastewater can be returned, for example, in a device or the like installed in the waste treatment process.

According to the DXN-containing wastewater treatment apparatus 20 shown in FIG. 1, the waste incineration process is performed in the waste incineration process including the combustion process, the cooling process, and the exhaust gas process by the waste incineration facility 21. DXN-containing waste water generated by contacting and / or washing the contacted object is collected, and the DXN-containing waste water is returned to at least one treatment step of each incineration treatment step to be treated and rendered harmless in the incineration treatment step. be able to.

In a particularly preferred example, the dioxin-containing waste water is returned to the garbage pit 22 by the switching device 35 and treated in the combustion treatment step.
3 and treated in the combustion treatment step, and the DXN-containing wastewater is returned to the cooling tower and evaporated in the cooling step, and detoxification is performed in the exhaust gas treatment step. Furthermore, the dioxin-containing wastewater can be treated in each treatment step of the garbage incineration treatment step in combination with each other to be rendered harmless in the exhaust gas treatment step.

As described above, in the embodiment shown in FIG. 1, the DXN-containing wastewater generated in the garbage incineration process by the garbage incineration facility is not sent to the adjacent wastewater treatment facility. Can be reduced. Therefore, it is possible to cope with the case where the emission standard is further revised due to the strengthening of regulations. Further, since the wastewater treatment equipment does not include the treatment of the DXN-containing wastewater, it can be made more compact accordingly.

Further, an advanced oxidation treatment equipment such as ultraviolet irradiation as an advanced treatment equipment is provided downstream of the coagulation sedimentation tank and the sand filtration tower.
The concentration of dioxins can be reduced without installing a membrane separation facility.

In the present invention, the amount of dioxin-containing wastewater returned to the refuse incineration treatment step is set to be smaller than the input water amount determined by the refuse incineration treatment capacity per unit handled in each treatment step of the incinerator in the refuse incineration equipment. As an example, in waste incineration facilities, generally, the amount of wastewater that can be treated by garbage calorie calculation is defined in order to satisfy the efficiency of a waste heat boiler or the like in the waste incineration facilities. As an example of study, incineration capacity 100t / day, garbage calories 2400kcal / kg,
Allowable range of reduction of garbage calories is 1000kcal / kg
Then, the amount of wastewater that can be treated using the generally known garbage calorie estimation formula based on three component values is 14.3 t / day.

At present, in most garbage incineration facilities, the above-mentioned dioxin-containing wastewater amount is several t / kg, and even if they are completely treated according to the present invention, they do not exceed the wastewater treatment capacity of the garbage incineration facility.

Although the waste incineration equipment has been described above as an example of the embodiment, it goes without saying that similar effects can be obtained for waste other than waste, for example, industrial waste of combustible materials. In addition, a stoker incinerator is used as the garbage incineration equipment, but the invention is not limited to this, and an incineration facility such as a fluidized bed or a kiln, a gasification and melting facility, or the like can also be used.

[0050]

As described above, the present invention provides a dioxin-containing wastewater system for collecting dioxin-containing wastewater generated in a waste treatment process, a water collecting tank for receiving the collected wastewater, and a method for collecting the wastewater from the water collecting tank. A simple treatment device for dioxins in wastewater installed in combination with wastewater return means that returns the wastewater to the treatment process can ensure the concentration of effluent water that can respond to stricter regulations in the future, installation costs, maintenance and replacement costs, The burden of operating costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment according to the present invention.

FIG. 2 is a diagram showing an example of a facility for treating dioxins in wastewater in a conventional garbage incineration facility.

[Explanation of symbols]

Reference Signs List 20 Dioxin-containing wastewater treatment apparatus 21 Garbage incineration equipment 22 Garbage pit 23 Incinerator 24 Economizer 25 Cooling tower 26 Dust collector 27 Chimney 28 Water collecting tank 29 Drainage supply system 29a, 29b, 29c Branch drainage supply system 30 Supply device 31 Injection Device 32 Ash melting device 33 Ash precipitation tank 34 Fly ash treatment device 35 Switching device M, M1, M2, M3, M4 Dioxin-containing wastewater system N Wastewater return means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C07B 35/06 F23G 7/04 601Z 37/06 B01D 53/34 134E C07D 319/24 B09B 3/00 303J F23G 7/04 601 ZAB (72) Inventor Junichi Ito 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term in Nihon Kokan Co., Ltd. (Reference) 3B201 AA46 BB21 BB82 BB88 BC00 CC00 4D002 AA21 AC04 BA05 BA12 BA13 CA01 EA02 4D004 AA46 AB07 CA24 CC03 DA02 DA06 4D034 AA26 CA04 CA13 CA19 DA05 4H006 AA05 AC13 AC26 BD41 BD52 BD84

Claims (8)

[Claims] When a waste is treated in a waste treatment process including a waste treatment process, a waste gas cooling process, and an exhaust gas treatment process by a waste treatment facility, the waste material is brought into contact with the waste treated material. And / or collecting dioxin-containing wastewater generated by washing a contacted object, returning the dioxin-containing wastewater to the above-mentioned treatment step, and treating and detoxifying the dioxin-containing wastewater. Method. 2. The dioxins in wastewater of a waste treatment facility according to claim 1, wherein the wastewater containing dioxins is contained in the waste, treated in a combustion treatment step, and detoxified in an exhaust gas treatment step. Processing method. 3. The method according to claim 1, wherein the wastewater containing dioxins is sprayed into a furnace installed in the combustion treatment step, treated in the combustion treatment step, and detoxified in the exhaust gas treatment step. 2. A method for treating dioxins in wastewater of a waste treatment facility according to item 2. 4. The dioxin-containing wastewater is returned to a cooling tower provided in a cooling treatment step, and evaporated in the cooling treatment step.
4. The method for treating dioxins in wastewater of a waste treatment facility according to claim 1, wherein the detoxification is performed in an exhaust gas treatment step. 5. A treatment apparatus for treating dioxins in waste water generated in a waste treatment step including a combustion treatment, a cooling treatment, and an exhaust gas treatment in a waste treatment facility having a waste supply facility, A dioxin-containing drainage system for collecting dioxin-containing wastewater generated in the waste treatment process, a water collecting tank for receiving the collected wastewater, and a wastewater return means for returning the wastewater from the water collection tank to the waste treatment process are assembled. A device for treating dioxins in wastewater of a waste treatment facility, which is installed together. 6. An apparatus for treating dioxins in wastewater of a waste treatment facility according to claim 5, further comprising means for returning wastewater containing dioxin-containing wastewater to a waste supply facility. 7. A wastewater treatment facility according to claim 5, further comprising a wastewater return means for returning the dioxin-containing wastewater to the inside of a furnace installed in the combustion treatment step. Dioxin processing equipment. 8. A waste treatment facility according to claim 5, wherein waste water return means for returning dioxin-containing waste water to a cooling tower installed in a cooling treatment step is provided. For treating dioxins in wastewater.