JPH03108697A - Treatment method for radioactive liquid waste - Google Patents

Abstract

PURPOSE:To enable effective removal of soluble and insoluble substances from a radioactive liquid waste of low radioactivity concentration by feeding radioactive liquid waste through a vessel in which larger particle sized activated carbon is filled at upper layers and smaller sized one is filled at lower layers. CONSTITUTION:A vessel 3 is filled by activated carbon in an order that particle sizes is larger in an upper layer 4a and smaller in a lower layer 4b, and radioactive liquid waste passes through the vessel. As the activated carbon is filled by that method, insoluble substance in the waste water such as a short thread is removed by the upper layer and soluble substances such as a detergent is removed by a highly adsorptive activated carbon in the lower layer. Accordingly, both soluble and insoluble substances can be removed without any clogging and therefore the radioactive liquid waste containing those substances can be very conveniently treated.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Field of Industrial Application) The present invention relates to a method for treating radioactive waste fluid generated from nuclear facilities, and in particular to a method for treating radioactive waste fluid such as washing water for clothes, hand washing, showering, etc. This invention relates to a treatment method suitable for extremely low waste liquid.

(Prior Art) Nuclear facilities, especially nuclear power plants, generate wastewater such as water used by workers for washing clothes, washing hands, and showering. The characteristics of such wastewater are that the radioactivity concentration is extremely low.
Contains detergent ingredients and insoluble ingredients such as lint, hair, and dirt. Currently, when processing these waste liquids, large debris such as lint is removed using a strainer, etc., and then the radioactivity is measured and the radioactivity is confirmed to be below the specified concentration before being released into the environment. .

However, in this method, various organic components such as detergent and grime in the waste liquid are released as they are, which is not preferable from an environmental conservation perspective.

(Problems to be Solved by the Invention) Therefore, an attempt was made to remove soluble and insoluble substances contained in wastewater at once using activated carbon. However, activated carbon has particle sizes ranging from 3 mm to 10 μm, and those with large particle sizes have low adsorption performance, making it difficult to remove soluble substances such as detergents, and those with small diameters have poor adsorption performance. Although the efficiency is high, it can become clogged, reducing processing capacity and requiring frequent backwashing operations.

The present invention was made in response to such a situation, and an object of the present invention is to efficiently remove soluble and insoluble substances from a radioactive waste liquid with a low radioactive concentration.

[Structure of the invention] (Means and effects for solving the problem) The above purpose is to
This can be achieved by filling a container with activated carbon in such an order that the particle size of the activated carbon is large in the upper layer and decreasing in particle size in the lower layer, and passing the radioactive waste liquid into the container.

In the present invention, activated carbon is filled into a container using the method described above, so insoluble substances such as lint in wastewater are removed in the upper layer, and soluble substances such as detergent are removed by the activated carbon with high adsorption capacity in the lower layer. be done. Therefore, both soluble and insoluble substances can be removed without causing clogging, which is extremely convenient for treating radioactive waste liquid containing these substances.

(Example) Embodiments of the present invention will be described with reference to the drawings.

First, in order to test the treatment method of the present invention, simulated waste liquids shown in Table 1 below were prepared.

Table 1 Using this simulated waste liquid, the waste liquid was filtered using the testing apparatus shown in FIG. In Fig. 1, 1 is a liquid supply tank, 2 is a pump, 3 is an activated carbon filling container, 4 is activated carbon, and 5 is a pump.
is the pressure gauge, and 6 is the backwash tank.

7 is compressed air, and 8 is a tank for backwashing.

Example 1 (comparative example) Particle size 10pm surface area! The activated carbon filling container 3 was filled with activated carbon having a weight of 500 nr/g and an average pore radius of 30 to 50 A, and the simulated liquid was supplied to the waste water supply tank 1. Next, the pump 2 was operated to send the simulated liquid to the activated carbon filled container 3, and the pressure was measured with a pressure gauge 5 installed at the outlet of the activated carbon filled container 3. When the pressure reached twice the initial pressure, the pump 2 was stopped, compressed air 7 was sent to pressurize the backwash tank 6, and the activated carbon was stored in the backwash tank 8.

Example 2 (Comparative Example) Activated carbon having a particle size of 2000 μm, a surface area of 1200 rrf/g, and an average pore radius of 10 to +5 A was filled into the activated carbon filling container 3, and the simulated liquid was filtered in the same manner as in Example 1 except for the above. .

Example 3 (Embodiment of the present invention) The lower 2/3 of the activated carbon filling container 3 was filled with the same activated carbon as in Example 1, the upper 1/3 was filled with the same activated carbon as in Example 2, and the rest was the same as in Example 1. The simulated liquid was filtered. A longitudinal cross-sectional view of this activated carbon-filled container is shown in FIG. In this figure, 4a is the activated carbon with a large particle size used in Example 2, and 4b is the activated carbon with a small particle size used in Example 1.

Further, 11 is a waste liquid supply port, and 12 is a drainage outlet.

The results of the above tests are shown in Table 2.

Table 2 As shown in the above table, in Example 1 in which only activated carbon with a small particle size was used, the pressure increased significantly due to clogging, and the amount of waste liquid treated until backwashing was only 201 kg. In addition, in Example 2 in which only activated carbon with a large particle size was used, the increase in pressure was small, but the quality of the outlet water deteriorated significantly.

On the other hand, in Example 3, the increase in pressure was small, the amount of waste liquid treated before backwashing reached 1001, and the quality of the outlet water was also good.

[Effects of the Invention] As explained above, according to the present invention, soluble substances and insoluble substances can be efficiently extracted from waste liquid with extremely low radioactivity concentration, such as washing water for clothes and hand-washing showers generated from nuclear facilities. substances can be removed.

[Brief explanation of drawings]

Figure 1 is a system diagram of the equipment used in the embodiment of the present invention, Figure 2
The figure is a longitudinal cross-sectional view of an activated carbon-filled container used in an example of the present invention. 1... Waste liquid supply tank 2... Liquid supply pump 3... Activated carbon filling container 4... Activated carbon 4a... Activated carbon with large particle size 4b... Activated carbon with small particle size 5... Pressure Total 6... Backwash tank 7... Compressed air 8... Backwash bones are in the tank

Claims (1)

[Claims] A method for treating radioactive waste liquid, characterized by passing the radioactive waste liquid through a container filled with activated carbon having a large particle size in the upper layer and activated carbon having a small particle size in the lower layer.