JPH0643292A - Radioactive waste liquid disposal device - Google Patents

Abstract

PURPOSE:To improve the facility disposal efficiency and provide the stable recovery water quality by mixing the powder activated carbon into a radioactive waste liquid, and filtering the mixed slurry. CONSTITUTION:A wash waste liquid is collected in a wash waste liquid collecting tank 11, the powder activated carbon is added each time the tank 11 is batch-processed, and a chemical oxygen requirement constituent and an n-hexane extract constituent are adsorbed in it. The waste liquid in the tank 11 at the time of waste liquid disposal is mixed when the powder activated carbon is added by the circulation flow of a pump 12. The mixed powder activated carbon and the suspended solid constituent slurry are fed to a rotary filter 14 via a switch valve 13. The rotary filter 14 separates the waste liquid into the processed water and the concentrated/dehydrated object (cake). The concentrated/dehydrated object is filled into a drum can 16 via a cake discharge valve 15. The waste liquid added with the powder activated carbon is directly filtered, no condensing/precipitating time is required, precise filtering is performed with the rotary filter 14, thus the stable recovery water quality is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radioactive liquid waste treatment apparatus for treating laundry liquid waste or shower drain as radioactive liquid waste generated in a nuclear power plant.

[0002]

2. Description of the Related Art Generally, laundry waste liquid or shower drain generated in a nuclear power plant is subjected to an appropriate treatment to remove detergent components and dirt components transferred from the laundry to the waste liquid by washing and then treating the treated water. It can be reused in the plant or discharged outside the plant.

The treatment of laundry waste liquid or shower drain is
Management of the radioactive substance concentration of treated water or the water quality (SS (suspended solids) concentration, COD (chemical oxygen demand) concentration, n-hexane extract concentration, PH) specified by the environmental impact survey at each power plant It is implemented so that it is less than or equal to the value.

As one of the treatment systems for washing waste liquid or shower drain, there is an apparatus for adding powdered activated carbon and coagulating sedimentation. An example of this apparatus will be described below with reference to FIG.

As shown in FIG. 3, the laundry waste liquid or shower drain (laundry waste liquid in FIG. 3) is collected in a collecting tank 1 and transferred to a coagulating sedimentation tank 2 for each batch. Powdered activated carbon having a concentration of about 1000 ppm is added to the coagulating sedimentation tank 2 to adsorb the COD component and the n-hexane extract component in the laundry waste liquid.

Next, the coagulation sedimentation tank 2 has a concentration of 300 ppm.
Add a coagulant (van sulphate soil) corresponding to the degree of COD
The powdered activated carbon adsorbing the component and the n-hexane extract component and the SS (suspended solid matter) component are aggregated and precipitated. here,
Most of the radioactive substances contained in the laundry waste liquid are SS components, and most of the radioactive substances also become precipitates by this treatment.

Further, the supernatant water of the coagulating sedimentation tank 2 is collected,
It can be reused in the plant or released to the outside of the plant. The sediment in the coagulation sedimentation tank 2 is drain-stored in the sedimentation separation tank 3 and then concentrated and dehydrated by a centrifugal dehydrator 4 and filled in a drum can 5. The decant water in the sedimentation tank 3 and the water collected by the centrifugal dehydration treatment are collected in the collection tank 1.

[0008]

By the way, the above-mentioned apparatus for treating laundry waste liquid requires a coagulation sedimentation time of 4 to 5 hours in the coagulation sedimentation tank 2, and this time becomes a waiting time, which is an average of the entire equipment. There is a problem that the processing capacity decreases.

Further, the removal of the powdered activated carbon and the SS component is carried out by a floating separation method utilizing coagulation sedimentation,
Compared with the microfiltration method, the quality of recovered water is unstable, such as the sedimentation characteristics differing depending on the properties of the waste liquid.

Further, in order to drum the coagulated sediment, a sedimentation / separation tank 3, a centrifugal dehydrator 4 and piping,
There is a problem that pumps are required and the equipment becomes large.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a radioactive waste liquid treatment apparatus having a good equipment treatment efficiency, a stable recovered water quality, and a compact equipment scale.

[0012]

In order to solve the above-mentioned problems, a radioactive liquid waste treatment apparatus according to the present invention comprises a mixing means for mixing powdered activated carbon with a radioactive liquid waste generated in a nuclear power plant, and And a rotary filter for filtering the mixed slurry mixed.

[0013]

In the present invention having the above-mentioned constitution, by directly filtering the radioactive waste liquid to which the powdered activated carbon is added,
Coagulation-sedimentation time is unnecessary. In addition, stable filtration water quality can be obtained by performing microfiltration using a rotary filter. Furthermore, a flocculation-sedimentation tank, a sedimentation-separation tank, a centrifugal dehydrator, piping, and pumps are unnecessary.

[0014]

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

FIG. 1 shows an embodiment of the radioactive liquid waste treatment apparatus according to the present invention. This radioactive waste liquid treatment device has a laundry waste liquid collection tank 11 as a mixing means, and the laundry waste liquid is collected in the laundry waste liquid collection tank 11 and powdered activated carbon is added thereto. Then, the waste liquid in the tank at the time of adding the powdered activated carbon and at the time of treating the waste liquid is mixed by the pump 12.

The mixed powdered activated carbon and the slurry of SS component are passed through a rotary filter 14 through an opening / closing valve 13 and then separated into treated water and a concentrated / dehydrated product (cake) through a cake discharge valve 15. To be done. The concentrated / dehydrated product is filled in the drum 16.

Here, the rotary filter 14 is shown in FIG.
As shown in FIG. 5, the filter plates 21 and the stirring plates 22 are alternately arranged in the pressure-resistant filter chamber 20 with a narrow gap, and the stirring plates 22 rotate at a constant speed during filtration. The filter plate 21 has a filtrate discharge mechanism 23, and filter cloth is stretched on both sides of the plate.

The raw material slurry is supplied under pressure from one of the filtration chambers 20 and is filtered and dehydrated while moving through the gap between the filtration plates 21. The cake is discharged in the form of a hard paste from the cake discharge valve 15 arranged on the other side of the filtration chamber 20, and the filtrate is discharged to the outside through the filtrate discharge mechanism 23 of the filter plate 21. The stirring plate 22 is a torque control device 24.
The torque is controlled by.

That is, the rotary filter 14 agitates the cake layer formed on the filter membrane by the agitating plate 22,
A filter that imparts fluidity to a cake having a certain thickness or more (more than a fixed cake layer), and the cake that has been concentrated and dehydrated is discharged outside the filter without interrupting the filtration process.

The rotary filter 14, like the powdered activated carbon slurry treated in this embodiment, is concentrated and
The dehydrated product is suitable for microfiltration treatment of a slurry having a thixotropic property.

There is a filter press as another general filter that can be adopted. This filter press uses a static cake layer, and the rotary filter is a unit because of the following reasons. The filtration area and the processing volume per unit time are large, which is suitable for the present invention.

That is, in the rotary filter, since the cake having a certain thickness or more (fixed bed or more) is in a fluidized state, the liquid flow rate is the same as when the fixed cake bed is passed, but the above filter is used. This is because the press requires a step of removing cake from the filter membrane as the cake layer grows.

Next, the operation of this embodiment will be described.

As shown in FIG. 1, the laundry waste liquid is collected in the laundry waste liquid collection tank 11, and the laundry waste liquid collection tank 1
Powdered activated carbon having a concentration of about 1000 ppm is added for each batch treatment of 1, and the COD component and the n-hexane extract component are adsorbed to this.

Next, the waste liquid in the tank 11 at the time of adding the powdered activated carbon and the waste liquid treatment is mixed by the circulating flow of the pump 12. The mixed powdered activated carbon and the SS component slurry are passed through the on-off valve 13 to the rotary filter 14 by the pump 12.

Then, the rotary filter 14 separates the waste liquid into treated water and a concentrated / dehydrated product (cake) through a cake discharge valve 15, and the concentrated / dehydrated product is filled in a drum 16.

As described above, according to the present embodiment, the coagulation-sedimentation time becomes unnecessary by directly filtering the waste liquid containing the powdered activated carbon. In addition, stable filtration water quality can be obtained by performing microfiltration using a rotary filter. Further, in this embodiment, the coagulation sedimentation tank, the sedimentation separation tank, the centrifugal dehydrator, the piping, and the pumps are unnecessary.

In the above embodiment, the laundry waste liquid has been described as the radioactive waste liquid, but the present invention is not limited to this, and a shower drain can also be applied.

[0029]

As described above, according to the radioactive waste liquid treatment apparatus of the present invention, by directly filtering the waste liquid to which the powdered activated carbon is added, the coagulation-sedimentation time which was conventionally required becomes unnecessary, and the treatment The time can be greatly reduced.

Further, by performing precision filtration using a rotary filter, a stable quality of recovered water can be obtained as compared with the conventional flocculation-precipitation (floating separation) method.

Further, the concentrated / dehydrated powdered activated carbon and SS component recovered from the rotary filter are equivalent to those recovered by the centrifugal dehydrator of the conventional system, and they are a coagulating sedimentation tank, a sedimentation tank, and a centrifugal dehydrator. Also, piping and pumps are not required. As a result, the equipment can be simplified.

[Brief description of drawings]

FIG. 1 is a schematic system diagram showing an embodiment of a radioactive liquid waste treatment apparatus according to the present invention.

FIG. 2 is a schematic diagram showing the internal structure of the rotary filter in FIG.

FIG. 3 is a schematic system diagram showing an example of a conventional laundry waste liquid treatment device.

[Explanation of symbols]

 11 Washing Waste Liquid Collection Tank (Mixing Means) 12 Pump 13 Open / Close Valve 14 Rotary Filter 15 Cake Discharge Valve 16 Drum Can

Claims (1)

[Claims] 1. A radioactive waste liquid treatment, comprising: a mixing means for mixing powdered activated carbon with a radioactive waste liquid generated in a nuclear power plant; and a rotary filter for filtering the mixed slurry mixed by the mixing means. apparatus.