JPH0557161A - Method for regenerating hollow fiber filter medium - Google Patents

Abstract

PURPOSE:To improve cleaning effect by using a new cleaning composition in the regeneration of oil-polluted hollow fiber filter medium. CONSTITUTION:Hollow fiber filter medium polluted with deposited suspended substance is cleaned with the following cleaning composition (wt.%): ethanol 50-60, water 10-30, sodium metasilicate 5-10, potassium hydroxide 3-5, surfactant 1-2, xylene 0.1-0.5. Oil is saponified by sodium metasilicate and potassium hydroxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hollow fiber membrane filtering apparatus for filtering a stock solution containing a suspension through a hollow fiber membrane filtering material to obtain a filtrate, and the suspension attached to the hollow fiber membrane filtering material. The present invention relates to a method for regenerating a hollow fiber membrane-made filter material that is washed with a detergent to regenerate the filtration ability.

[0002]

2. Description of the Related Art Nuclear power facilities, especially nuclear power plants, generate waste water for washing clothes used by workers, hand washing, showers and the like, and radioactive waste water containing machine oil and the like. These wastewaters are characterized by high concentrations of organic components in sebum, proteins, bacteria and mineral oils. Such wastewater has an extremely low radioactivity concentration, contains a floating suspension of detergent components, lint, hair, dust and the like, and has a high chemical oxygen content (COD) due to the detergent components, shampoo and the like. When treating these wastewaters, the floating suspension removes large debris such as lint with a strainer, etc., and after filtering through a hollow fiber membrane filtration device, the radioactivity is measured and radioactivity below the specified concentration is measured. Confirm that it is released into the environment. The hollow fiber membrane filtering device comprises a hollow fiber membrane, for example, a plurality of elongated filamentous hollow fibers of an organic polymer compound, which are bundled in a tank and incorporated as a filter medium.

[0003]

When a suspension in water is filtered through a hollow fiber membrane, the filtered particles, oil, etc. adhere to the surface of the hollow fiber membrane, and the filtration efficiency gradually decreases.
In particular, if a sticky substance such as oil is attached, it is very difficult to regenerate it. In such a case, there is known a method of cleaning with hydrogen peroxide or a cleaning agent in which alcohol and a small amount of potassium hydroxide dissolved in alcohol are dissolved.

However, washing with hydrogen peroxide is not soluble and decomposes oil components by oxidizing power, so that the effect is not sufficient and there is a problem of deterioration of the hollow fiber membrane. Further, cleaning with alcohol is not sufficient in cleaning effect like hydrogen peroxide, and there is a problem such as fire. The method of adding a small amount of potassium hydroxide that is soluble in alcohol improves the cleaning effect to some extent, but since potassium hydroxide does not dissolve in alcohol in a large amount, the cleaning power does not increase significantly.

The present invention has been made to solve the above-mentioned problems, and it is a hollow fiber membrane filter material capable of efficiently cleaning and regenerating oil, bacteria and floating suspensions attached to the hollow fiber membrane. Is to provide a method of reproducing.

[0006]

According to the present invention, an undiluted solution containing a suspension is filtered through a hollow fiber membrane filter material, and the oil-contaminated hollow fiber membrane filter material is used in a weight percentage of methyl alcohol or ethyl alcohol. , At least one selected from butyl alcohol 50-60%, water 10-30%, at least one selected from sodium metasilicate or sodium orthosilicate, at least one selected from potassium hydroxide, sodium hydroxide and sodium carbonate 3-5%, surfactant 1-2
%, Xylene, benzene, toluene, and at least one selected from 0.1 to 0.5%.

[0007]

The reasons for limiting the composition and the component ratio of the detergent used in the present invention are as follows. (1) At least one selected from methyl alcohol, ethyl alcohol and butyl alcohol: 50-60%

The above alcohol is used to remove oil, and if it exceeds 60%, it is subject to the regulation of dangerous substances by the Fire Service Law, so if it is handled in large quantities, there is a possibility of burning and it is dangerous. On the other hand, if it is less than 50%, the cleaning effect on oil is thin and undesirable. About 10 to 30 tons of cleaning agent is required to clean the hollow fiber membrane filter media used in the nuclear power plant. It is dangerous to use such a large amount of alcohol in pure (~ 100%). Is. (2) Water: 10-30%

Water dissolves compounds such as sodium metasilicate, potassium hydroxide and a surfactant, and these compounds are not soluble in alcohol. The amount of water is 10
Departure from -30% is not desirable due to solubility. (3) At least one of sodium metasilicate and sodium orthosilicate: 5 to 10%

Sodium meta or orthosilicate is a dispersant for dispersing oil in alcohol or water, and its necessary amount is determined by the solubility of water-alcohol type solvent, and it may deviate from 5 to 10%. Not desirable. (4) At least one selected from potassium hydroxide, sodium hydroxide and sodium carbonate: 3 to 5%

These are for degreasing the oil content from the hollow fiber membrane, and the amount thereof is determined by the solubility of the water-alcohol solvent. Therefore, deviation from 3-5% is not desirable. (5) Surfactant: 1-2%

As the surfactant, for example, sodium dodecylbenzenesulfonate is used as the anionic surfactant, and nonylphenyl polyoxyethylene ether is used as the nonionic surfactant. Even if two types are used, the effects are the same.

When the amount of the surfactant is 1 to 2%, micelles are formed (the amphipathic substance dissolves the oil with the hydrophilic group and the lipophilic group facing inward), but the amount is out of the range of 1 to 2%. Is not desirable. (6) At least one selected from xylene, benzene, and toluene: 0.1 to 0.5% These are necessary to dissolve the oil component, and the amount is determined by the solubility in water, and it is out of the range of 0.1 to 0.5%. Is not desirable.

[0014]

EXAMPLE An example of a method for recycling a hollow fiber membrane-made filter material according to the present invention will be described with reference to FIG.

FIG. 1 shows a system diagram of a test apparatus for confirming the effect of this embodiment. In the figure, reference numeral 1 is a stock solution tank storing a stock solution 2, and a solution supply pipe 5 for feeding the stock solution 2 to a filtration device 4 having a hollow fiber membrane-made filter material 3 incorporated therein is connected to the stock solution tank 1. A liquid supply pump 6, a first valve 7 and a first pressure gauge 8 are sequentially connected to the liquid supply pipe 5. A filtrate outflow pipe 9 is connected to the upper end of the filtration device 4. The filtrate outlet pipe 9 has a second pressure gauge 10 and a second valve.
11, a flow rate adjusting valve 12, a flow meter 13, a thermometer 14 and an integrating flow meter 15 are sequentially connected. A cleaning agent tank 16 is connected to a side surface of the filtering device 4 via a third valve 17 by a cleaning agent feeding pipe 18. An air supply source 19 is connected to the lower end of the filtering device 4 by a bubbling gas supply pipe 21 via a fourth valve 20. In addition, at the lower end of the filtration device 4, the cleaning liquid outflow pipe 23
Is connected, and the other end of the liquid supply pipe 5 is connected to the cleaning liquid outflow pipe 23. The cleaning liquid outflow pipe 23 is connected to the cleaning liquid receiving tank 24 via the fifth valve 22. In the test apparatus, the stock solution 2 is simulated in the composition shown in Table 1 and stored in the stock solution tank 1.

[0016]

[Table 1]

Further, in the cleaning agent tank 16, in weight%, ethyl alcohol 60%, water 22.5%, sodium metasilicate
Fill a detergent consisting of 10%, potassium hydroxide 5%, surfactant 2% and xylene 0.5%.

Here, the first and second valves 7, 11 and the flow rate adjusting valve 12 are opened, and the third, fourth and fifth valves 17, 20,
Close 22. The liquid supply pump 6 is driven, a predetermined flow rate is set according to an instruction from the flow meter 13, and the stock solution 2 is continuously supplied into the filtration device 4. At this time, the inlet pressure of the filtration device 4 is measured by the first pressure gauge 8 and the outlet pressure thereof is measured by the second pressure gauge 10. When the specified pressure is reached, the liquid supply pump 6 is stopped. The first valve 7 and the second valve 11 are closed. Then, the third valve 17 is opened from the cleaning agent tank 16 to allow the cleaning agent to flow into the filtering device 4.
At this time, the fourth valve 20 is opened and air is blown into the filter device 4 from the air supply source 19 to perform bubbling. After a lapse of a predetermined time, the fifth valve 22 is opened and the cleaning liquid is stored in the cleaning liquid receiving tank 24 through the cleaning liquid outflow pipe 23. The hollow fiber membrane filter material 3 is regenerated by this washing operation. Then, the stock solution 2 simulated in Table 1 is supplied again to the filtration device 4, and the hollow fiber membrane-made filter material 3 is used for the filtration operation. The results of the washing operation of the hollow fiber membrane-made filter material 3 after the filtration operation are shown in Table 2.

[0019]

[Table 2]

As is apparent from Table 2, according to the present example, the hollow fiber membrane filter material having a high differential pressure due to oil, bacteria and floating suspension was washed with the detergent having the above composition, and It is recognized that the differential pressure has been restored.

[0021]

EFFECTS OF THE INVENTION According to the present invention, an oil-contaminated filter material made of hollow fiber membrane is efficiently regenerated by washing it with a detergent containing alcohol, water, sodium metasilicate, potassium hydroxide or the like as a main component by a saponification reaction. can do.

[Brief description of drawings]

FIG. 1 is a system diagram showing a test device for confirming the effect of a cleaning agent in an example of a method for recycling a hollow fiber membrane-made filter material according to the present invention.

[Explanation of symbols]

1 ... Stock solution tank, 2 ... Stock solution, 3 ... Hollow fiber membrane filter material, 4 ...
Filtration device, 5 ... Liquid supply pipe, 6 ... Liquid supply pump, 7 ... First valve, 8 ... First pressure gauge, 9 ... Filtrate outflow pipe, 10 ... Second pressure gauge, 11 ... Second valve , 12 ... Flow control valve, 13 ... Flow meter, 14
... thermometer, 15 ... integrated flow meter, 16 ... detergent tank, 17 ... third valve, 18 ... detergent supply pipe, 19 ... air supply source, 20 ... fourth
Valve, 21 ... Bubbling gas supply pipe, 22 ... Fifth valve, 23 ...
Cleaning solution outflow pipe, 24 ... Cleaning solution receiving tank.

Claims (1)

[Claims] 1. An undiluted solution containing a suspension is filtered through a hollow fiber membrane filter material, and the oil-contaminated hollow fiber membrane filter material is at least selected from methyl alcohol, ethyl alcohol and butyl alcohol in weight%. 50-60% of one kind, water 10
-30%, at least one of sodium metasilicate or sodium orthosilicate, at least one selected from potassium hydroxide, sodium hydroxide, sodium carbonate 3-5%, surfactant 1-2%, xylene, benzene,
A method for regenerating a hollow fiber membrane-made filter medium, which comprises washing with a detergent comprising 0.1 to 0.5% of at least one selected from toluene.