JPS6244696A - Electrolytic processing method of waste water - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to the purification of nuclear power plant cooling water, radioactive liquid waste, general industrial wastewater, and the like.

[Background of the invention]

There are small amounts of corrosive substances in equipment such as condensers and heaters, or in piping, in the cooling water of nuclear power plants.

This corrosion product is mainly composed of iron oxide, iron hydroxide, etc., and is called cladding.

When this cladding is brought into a nuclear reactor, it adheres to the surface of the fuel rod and is irradiated with neutrons to activate cobalt, nickel, etc. in the cladding. Later, these radioactive cruds adhere to and accumulate on equipment, piping, etc., posing a problem in preventing radiation exposure for workers. In addition, the radioactive crud in the cooling water is collected as blow water from one equipment, treatment equipment regeneration, and backwash waste liquid to the radioactive waste treatment facility. Therefore, in order to prevent these cruds from entering the reactor as much as possible, they are removed by the condensate system, reactor purification system, radioactive liquid waste treatment system, etc.

Hitherto, as a crud removal method, a filtration demineralizer and a demineralizer have been used in combination as necessary, but a large amount of filtration agent, resin, etc. is generated as waste. In addition, non-auxiliary filters have problems such as reduced backwash recovery performance due to clogging and high cost.Currently, a new type of filter that generates less secondary waste and prevents clogging is being developed. The development of filters is desired.

In addition, as a related technique, for example, Japanese Patent Application Laid-Open No. 54-27
No. 259, Utility Model Publication No. 56-46874, etc.

[Purpose of the invention]

The purpose of the present invention is to provide an electrolytic cell filled with a porous conductive material via an insulating filter or a hydrophobic insulating material, etc. in the purification of nuclear power plant cooling water, radioactive liquid waste, general industrial wastewater, etc. An object of the present invention is to provide a method for removing iron oxide suspended solids, ions, etc. by applying electricity to the iron oxide.

[Summary of the invention]

The present invention relates to a method and apparatus for removing iron oxides, suspended solids, and ions contained in nuclear power plant cooling water radioactive liquid waste and general industrial wastewater, and relates to an insulating filter or a hydrophobic insulating filter. A direct current is applied to the polygonal column electrolytic structure filled with the porous conductive material through the porous conductive material, and the filling is positively and negatively charged through the insulator. This neutralizes the charge on the iron oxide or uses the electrical method to 'Jb#:14k='J15. *f:
In other words, in the negatively charged region of the bipolar filling, iron oxide, which has a positive surface potential in the neutral state, is removed by charge neutralization. Then, iron oxides having a negative surface potential are removed in the same manner, and iron oxides having a positive surface potential are moved to the insulating filter or the like side by the electrophoretic effect and captured and removed.

In addition, since the insulating filter and the like have positive and negative electrodes at both ends, ions are removed by occlusion electrodeposition.

The structure uses a cathode material with a pore size that does not allow the filling to flow out in the polygonal columnar outer shell, and an insoluble anode such as a ferrite rod or platinum plated rod that does not elute even when DC current is applied to the center of the unit. A porous conductive material is filled in a layer through an insulating filter or a hydrophobic insulating material.

In operation, water is passed in an upward flow from the bottom to the top of the electrolytic cell, and the energization method is set to a direct current within a range that causes water electrolysis.

[Embodiments of the invention]

Figure 1 shows a schematic diagram of a typical radioactive liquid waste treatment facility in a nuclear power plant.

This system is composed of a waste liquid receiving tank 1, a waste liquid transfer pump 2, a filtration device 3, a solution device 4, and a treated water tank 5.

The waste liquid containing iron oxides and ions collected in the waste liquid receiving tank 1 is distributed by the waste liquid transfer pump 2 to the filtration chlorinator 3, where the iron oxides are removed, and then the ions are removed by the demineralizer 4. After removal, it is transferred to the waste liquid collection tank 5.

Next, FIG. 2 shows a schematic system of radioactive liquid waste processing equipment as an example of equipment to which the present invention is applied.

An electrolytic purification system of the present invention instead of a filtration system and a desalination system Wt
By incorporating 6, iron oxides and ions can be removed, equipment costs can be reduced, and the amount of waste can be significantly reduced.

Next, an example of the schematic structure of the present invention is shown in FIG.

The device 7 is in the form of a pressure-resistant container, into which a polygonal columnar electrolytic structure 8 is fixed with a support 9 having a pore size large enough to prevent the filling material from flowing out.

The waste liquid is passed through the electrolytic structure 8 from the lower part, collected from the upper part, and purified in the electrolytic structure 8. The direct current required for this is operated by an external power source 10 by connecting the anode and cathode of the electrolytic structure 8 in parallel.

Next, the details of the electrolytic structure are shown in FIG.

The outer shell (cathode) 11 of the polygonal columnar electrolytic structure is fixed by a support 9, and an insoluble anode 12 is inserted in the center thereof. A porous conductive material 13 is formed between the two, and an insulating filter or a hydrophobic insulating material 15 is inserted between them with spacers 14 for venting gas being interposed at both ends.

Note that for the connection between the anode part 16 and the cathode part 17 and the support body 9, an electrical insulating material is provided, or only the anode part is insulated.

The function of the structure is that the filling material becomes bipolarized as an anode and a cathode and is charged by direct current. The cathode part electrically stores cations such as cobalt ions, and the anode part electrically stores anions such as chlorine ions. Further, iron oxides are deposited by charge neutralization in charged regions having a polarity opposite to the respective surface potentials.

Further, iron oxides having surface potentials of the same polarity move due to the electrophoretic effect and are captured and held by an insulating filter or the like. In this way, each impurity can be removed.

An experiment to demonstrate the effects of the present invention will also be described.

It is difficult to simulate the cooling water and radioactive liquid waste of a real nuclear power plant, and experiments show the effectiveness of removing Co ions and α-Fe203. In addition, the experimental method was a water flow method in consideration of applicability to actual equipment.

First, FIG. 5 shows the electrolytic cell used in the experiment. The size of the electrolytic cell is 40 x 40 x 150 m, and an electrolytic section is provided in the middle. The electrolytic part contains activated carbon fiber 18 as a filler,
(Log-DRy) Nylon fiber Ig-DRy 20 was inserted as an insulating filter in the center with nylon thread 19 interposed at both ends as a spacer for degassing. The supporting electrode is a platinum plated plate 21 of 40 x 100 mm for both the anode and cathode.
was used. In the experiment, a cobalt chloride solution with a predetermined concentration and a solution containing iron oxide (Ill) with an average particle size of 1 μm were used, and changes in the respective iron and ion concentrations were measured under a constant current. For concentration analysis, an atomic absorption spectrometer was used in both cases.

) Yo f, M(7)□6i□□69ooh.

□, Yo, 14, 3 mg/A of a-Fe, 03
Using 40ff of the containing liquid, changes in iron concentration with respect to water flow time are observed.

It can be seen from this that in the non-current state, the iron oxide cannot be completely removed, but when 0.05 A of current is applied, it is rapidly removed. In this way, the surface potential of iron oxide particles in distilled water is positively charged, so the filler is kept in the negatively charged region, and the insulating filter in the positively charged region also has many It has been confirmed that iron oxides are captured.

Next, the removal characteristics of Co ions are shown in FIG.

The stock solution is 11/Q using 4011 cobalt chloride solution.
The energization state is similar to that of iron oxide. It is thought that when electricity is applied, the activated carbon fiber becomes bipolar through the insulating filter, and the pores occlude ions that are oppositely charged to the respective electrodes.

The above experimental results show that iron oxides and ions can be removed at a high removal rate.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram of a radioactive liquid waste treatment facility in a power generation nuclear power plant according to an embodiment of the present invention, FIG. 2 is a schematic system diagram of a radioactive liquid waste treatment facility of the present invention, and FIG. 4 is a schematic structural diagram of the purification device of the present invention, FIG. 4 is a structural diagram of the electrolytic structure of the purification device of the present invention, FIG. The figure is an explanatory diagram showing experimental results demonstrating the present invention. 1... Waste liquid receiving tank, 2... Waste liquid transfer pump, 3...
... Filtration demineralizer, 4 ... Demineralizer, 5 ... Treated water tank, 8 ... Electrolytic structure, 10 ... External power supply, 11.
... Outer shell of electrolytic structure, 18 ... Activated carbon fiber, 21
...Platinum plated plate.

Claims (1)

[Claims] 1. In the electrolytic treatment method for iron oxides, suspended solids, and ions contained in cooling water of nuclear power plants, radioactive liquid waste, general industrial wastewater, etc., an insulating material and porous material are used between the supporting anode and the cathode. 1. An electrolytic treatment method for wastewater, which comprises alternating conductive materials and having a charged part and a trapping part to separate and remove iron oxides and ions.