JP2002143861A - Slime treating and slime treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively treat slime by intermittently adding hydrogen peroxide produced by electrolysis in the treatment site of slime to the slime treating system. SOLUTION: After hydrogen peroxide continuously produced by electrolysis in a hydrogen peroxide generator 35 is reserved in a hydrogen peroxide charger 37, a specified amount of the hydrogen peroxide is intermittently added to the slime treating system 32. The charger 37 reserves the hydrogen peroxide aqueous solution continuously supplied from the hydrogen peroxide generator 35 in a tank 20 and intermittently discharges the hydrogen peroxide aqueous solution from the tank 20 by using a siphon, float valve mechanism, timer type electromagnetic valve or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slime treatment apparatus and a slime treatment method for adding hydrogen peroxide as a slime control agent. The present invention relates to a slime treatment apparatus and a slime treatment method for preventing slime from being generated by intermittent addition to a system.

[0002]

2. Description of the Related Art Industrial water systems, including water systems for cooling, metalworking fluid systems, water systems for papermaking (papermaking process water, coating solutions for paper, latex, glue, etc.) and water systems for fabric production, swimming pools, etc.
Microorganisms are present in various water systems such as recreational water systems including fountains, ornamental ponds and ornamental running water systems, toilet water systems, water tank water systems, sanitary water systems such as septic tank water systems and sewage treatment water systems. While generating a viscous substance, it adheres and multiplies on the tube wall or vessel wall to form slime. When such slime is generated, for example, in a cooling water system, problems such as a decrease in heat exchange efficiency, corrosion of the piping surface, and blockage in the piping system are caused. In a papermaking water system, slime adhered to a wall surface falls off and causes product defects such as paper breakage and spots.

Conventionally, in order to prevent the generation of such water-based slime, a chlorine agent has been added to the water-based system as a slime control agent. However, the use of chlorinated agents is being avoided in recent years because hypochlorous acid generated from the chlorinated agent reacts with organic matter in water to form an organic chlorine compound.

[0004] Therefore, application of hydrogen peroxide as a slime control agent instead of a chlorine agent has been studied.

[0005] Since hydrogen peroxide is unstable and cannot be stored for a long period of time, and has a problem in safety during transportation, when hydrogen peroxide is used as a slime control agent, it must be used at a slime treatment site. It is necessary to produce hydrogen peroxide and add it to the slime treated system.

As one of the methods for producing hydrogen peroxide, a method has been proposed in which oxygen is electrolytically reduced by a cathode in an electrolytic cell to produce hydrogen peroxide. According to this method, hydrogen peroxide is produced continuously and at a constant production rate.

[0007]

When a slime control agent such as hydrogen peroxide is added to a slime treatment system,
Continuous addition of low concentrations of drug is not effective for slime control. On the other hand, continuous addition of a high-concentration chemical has a problem of corrosion of the piping system due to the oxidizing power of the chemical.

Accordingly, it is desired that hydrogen peroxide be added intermittently to the slime-treated system as a chemical solution having a predetermined concentration. Since hydrogen is produced continuously and at a constant production rate, if it is directly added to the slime-treated system, hydrogen peroxide will be continuously added to the slime-treated system, and the intermittent addition method It does not become. Intermittent production of hydrogen peroxide by continuously operating the electrolytic cell is not preferable from the viewpoint of maintaining the performance of the electrode of the electrolytic cell. For this reason, hydrogen peroxide is continuously added to the slime treatment system at a constant speed from an electrolytic cell continuously operated at a constant current, and the slime suppression effect tends to be insufficient.

The present invention solves the above-mentioned conventional problems, and effectively intermittently adds hydrogen peroxide produced by electrolysis at a slime treatment site to a slime treatment system to thereby provide an effective slime. An object of the present invention is to provide a slime processing device and a slime processing method for performing processing.

[0010]

According to the present invention, there is provided a slime treatment apparatus comprising: means for producing a hydrogen peroxide-containing liquid by electrolysis; means for receiving and storing the hydrogen peroxide-containing liquid produced by the means. Means for intermittently adding a predetermined amount of the hydrogen peroxide-containing liquid in the storage means to the slime treatment system.

According to the slime treatment method of the present invention, a hydrogen peroxide-containing liquid is produced by electrolysis, and the obtained hydrogen peroxide-containing liquid is stored, and then a predetermined amount thereof is intermittently added to the slime treatment system. It is characterized by the following.

In the slime treatment apparatus and the slime treatment method of the present invention, hydrogen peroxide continuously generated by electrolysis at the slime treatment site is temporarily stored, and a predetermined amount is intermittently transferred to the slime treatment system. To obtain a good slime treatment effect.

In the slime treatment apparatus of the present invention, the means for producing the hydrogen peroxide-containing liquid includes an electrolytic cell having an anode chamber and a cathode chamber, and a first chamber and a second chamber partitioned by a cation exchange membrane. And a dialysis cell having a dialysis cell having an anode effluent flowing out of the anode chamber of the electrolytic cell is introduced into the first chamber, and a cathode effluent flowing out of the cathode chamber is introduced into the second chamber. Preferably, alkali metal ions in the cathode effluent permeate the cation exchange membrane and migrate into the anode effluent.

With this hydrogen peroxide producing means, a hydrogen peroxide solution having a small alkali content can be obtained as follows. That is, an aqueous solution of a neutral salt is used as an anolyte, alkali metal ions such as sodium ions in the anode compartment are moved to the cathode compartment, and hydrogen peroxide and Na
Generates an alkali metal hydroxide such as OH. And
The acidic anode effluent and the alkaline cathode effluent obtained by this electrolytic treatment are introduced into a dialysis tank for dialysis. When the anode effluent is passed through the first chamber of the dialysis cell partitioned by the cation exchange membrane and the cathode effluent is passed through the second chamber, Na ions and the like in the catholyte are passed through the dialysis cell. The alkali metal ions permeate the cation exchange membrane and move to the anode effluent having a low ionic potential. In this dialysis tank, hydrogen peroxide ions are anions and cannot pass through the cation exchange membrane. Therefore, by passing the solution through the dialysis tank, the anode effluent changes from a mixture of an acid such as sulfuric acid and a salt such as sodium sulfate to a solution mainly containing a salt component such as sodium sulfate, and is used again as the anode electrolyte. It is possible to do. On the other hand, the cathode effluent is a hydrogen peroxide solution having a low alkali metal ion concentration.

[0015]

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

First, a hydrogen peroxide producing apparatus suitable for the present invention will be described with reference to FIG.

FIG. 1 is a system diagram showing a configuration of a hydrogen peroxide producing apparatus according to an embodiment.

The electrolytic cell 1 is divided into an anode chamber 3 and a cathode chamber 4 by a cation exchange membrane 2. An anode 5 is installed in the anode chamber 3, and a cathode 6 is installed in the cathode chamber 4. A DC voltage is applied to the anode 5 and the cathode 6 by a voltage application device 7.

As the cation exchange membrane 2, an olefin-based membrane,
Fluoroolefin-based ones can be used, but fluoroolefin-based ones are preferred. Further, as the ion exchange group, a sulfone group or a carboxyl group is suitable.

As the anode 5, it is preferable to use an acid-resistant and insoluble electrode such as a noble metal. That is, since alkali metal ions are removed from the anode chamber 3 and hydrogen ions are generated, the inside of the anode chamber 3 becomes acidic. If the anode material that comes into contact with this acidic solution elutes as cations, it is attracted to the cathode side and precipitates on the cathode side of the cation exchange membrane, which causes problems such as the difficulty in flowing current. It is preferably used. An example of such an electrode is an electrode in which titanium is coated with platinum.

An aqueous solution of a neutral salt such as Na ₂ SO ₄ is preferably introduced into the anode chamber 3 from a neutralization tank 12 described later.

The neutral salts include sulfuric acid, hydrochloric acid, nitric acid,
Alkali metal salts of mineral acids such as phosphoric acid are suitable. Preferably, sodium sulfate is used. When a halide such as sodium chloride is used, it is necessary to select an electrode material having a low oxygen generation potential so as not to generate chlorine gas. Therefore, it is desirable to use a neutral salt whose anion is not halogen.

Water is introduced into the cathode chamber 4. The water is preferably water to which an electrolyte such as NaCl or NaOH has been added to soft water or pure water excluding the hardness component in order to reduce electric resistance.

When a DC voltage is applied between the anode 5 and the cathode 6 by the voltage application device 7, the anode chamber 3 becomes acidic (for example, sulfuric acid). The cathode chamber 6 becomes alkaline, and oxygen generated by electrolysis is reduced to generate H ₂ O ₂ .

The sulfuric acid acidic effluent from the anode compartment 3 is passed through the anode effluent passage chamber (first chamber) 9 of the dialysis tank 8, where H ₂ O ₂ and alkali metal ions from the cathode compartment 4 are passed. The contained effluent is passed through the cathode effluent passage chamber (second chamber) 10 of the dialysis tank 8. A cation exchange membrane 11 is defined between the two chambers 9 and 10. It is preferable to provide a mesh-shaped flow path material made of a fluororesin or the like in these chambers 9 and 10.

As described above, while each of the effluents passes through these chambers 9 and 10, alkali metal ions such as Na in the cathode effluent are transferred to the cation exchange membrane 11 toward the anode effluent having a low ion concentration. And migrate through. Therefore, from the cathode effluent passage chamber 10, H ₂ O having a low alkali metal ion concentration is obtained.
₂ containing liquid is taken out.

Permeation of alkali metal ions such as Na ions
Come and SO₄Ion is Na₂SO ₄Room 9
The effluent is sent to the neutralization tank 12 via the pipe 9a. This
Of the liquid detected by the pH meter 13 in the neutralization tank 12
Tank so that H has a predetermined weakly acidic or neutral pH
The concentrated NaOH aqueous solution in 14 operates the pump 15 and the valve 16.
Through the neutralization tank 12. In this neutralization tank 12
Is supplied to the anode chamber 3 of the electrolytic cell 1 through a pump 17.
Paid and reused.

When a plurality of electrolytic cells are provided, the anode effluent from one electrolytic cell may be reused as the anolyte for another electrolytic cell.

With such an apparatus for producing hydrogen peroxide,
By keeping the amount of water supplied and the amount of power supplied to the electrolytic cell constant, a H ₂ O ₂ aqueous solution having a constant concentration can be obtained at a constant flow rate.

In the present invention, an aqueous hydrogen peroxide solution continuously produced in such a hydrogen peroxide producing apparatus is temporarily stored in a storage tank, and a predetermined amount of the aqueous solution is intermittently added to the slime treatment system from the storage tank. .

Next, hydrogen peroxide storage / addition means for storing an aqueous hydrogen peroxide solution continuously fed from such a hydrogen peroxide production apparatus and intermittently adding a predetermined amount thereof will be described with reference to FIG. This will be described with reference to FIG.

FIG. 2 shows hydrogen peroxide storage and storage according to the embodiment.
It is sectional drawing which shows an addition means.

The hydrogen peroxide storing and adding means shown in FIG. 2A receives the aqueous hydrogen peroxide solution supplied from the hydrogen peroxide producing apparatus via the pipe 21 into the tank 20,
When the water level in 0 rises to a predetermined water level (the highest level of the siphon pipe 22), the aqueous solution of hydrogen peroxide in the tank 20 is intermittently supplied from the siphon pipe 22 to the slime processing system by the siphon principle. Things.

When the water level in the tank 20 drops to the level at the inlet of the siphon pipe 22, the siphon breaks,
The liquid is stored again in the tank 20.

The hydrogen peroxide storing and adding means shown in FIG. 2B receives the aqueous hydrogen peroxide solution supplied from the hydrogen peroxide producing apparatus via the pipe 21 into the tank 20,
By opening and closing a float valve 26 that closes an opening of an injection pipe 23 provided at the bottom of the tank 20 with the buoyancy of a float 24, the aqueous solution of hydrogen peroxide in the tank 20 is intermittently supplied to the slime treatment system. is there.

The float valve 26 is supported by a shaft support member 27 so as to be vertically rotatable. The float 24 is connected to the float valve 26 by a bore 25, and the float 24 rises as the water level in the tank 20 rises.

When the liquid accumulates in the tank 20 until the buoyancy of the float 24 becomes equal to or more than a predetermined value, the float valve 26 is pulled up through the bore 25, whereby the peroxide in the tank 20 is opened through the opening of the injection pipe 23. The aqueous hydrogen solution flows out. The float valve 26 has a specific gravity smaller than that of water. Once the float valve 26 is pulled up from the opening of the injection pipe 23, the float valve 26 is kept away from the opening until all the liquid in the tank 20 flows out. When the entire amount of the aqueous solution of hydrogen peroxide in the tank 20 is discharged, the float valve 26 closes the opening of the injection pipe 23 again, and the aqueous solution of hydrogen peroxide is stored in the tank 20.

The hydrogen peroxide storage / addition means shown in FIG. 2 (c) receives the aqueous hydrogen peroxide solution supplied from the hydrogen peroxide producing device via the pipe 21 into the tank 20,
By opening the solenoid valve 28 of the injection pipe 23 provided at the bottom of the cylinder 0 for a predetermined period of time by a timer,
The aqueous solution of hydrogen peroxide in the tank 20 is intermittently supplied to the slime treatment system.

In any of the hydrogen peroxide storage / addition means, a hydrogen peroxide aqueous solution flows into the tank 20 at a constant flow rate from the hydrogen peroxide producing apparatus. From this tank 20, a siphon pipe 22, a float valve mechanism or a timer solenoid valve 2
In step 8, a predetermined amount of an aqueous solution of hydrogen peroxide is added to the slime treatment system at predetermined intervals.

In the present invention, hydrogen peroxide storage and storage
The addition means is capable of storing an aqueous solution of hydrogen peroxide continuously fed from the hydrogen peroxide production device and adding a predetermined amount of the aqueous solution of hydrogen peroxide to the slime treatment system at predetermined intervals. It suffices if there is, and it is not limited to what is shown in FIG.

According to the present invention, a predetermined amount of the hydrogen peroxide continuously produced by the electrolysis is intermittently injected into the slime treatment system, so that the hydrogen peroxide has a relatively high concentration. The slime is injected into the treatment system, and effective slime treatment can be performed without causing problems such as corrosion of the base material in the slime treatment system.

The concentration of hydrogen peroxide injected into the slime treatment system and the frequency of intermittent injection are determined as appropriate according to the water quality and operating conditions of the slime treatment system. In processing, 100-
It is preferable to add a hydrogen peroxide aqueous solution of about 10,000 ppm once every 1 to 72 hours in an amount of about 0.1 to 20% of the circulating water amount.

[0043]

The present invention will be described more specifically below with reference to examples and comparative examples.

Example 1 A slime treatment experiment was performed by adding hydrogen peroxide in the circulating cooling water system shown in FIG.

The circulating water system of the cooling tower shown in FIG.
The first cooling water is supplied to a heat exchange unit (refrigerator condenser) 33 by a feed pipe 32 provided with a pump P to exchange heat, and then returned to the cooling tower 31 by a return pipe 34. The hydrogen peroxide generated in the vessel 35 is fed from a pipe 36 to a hydrogen peroxide input device 37, where it is temporarily stored, and then intermittently injected into a feed pipe 32 from a pipe 38. The return pipe 34 is provided with a SUS short pipe 39 for measuring the amount of slime adhered and a short pipe 40 to which a copper piece 40A for measuring corrosion loss is attached. 41 is a makeup water supply pipe, and 42 is a blow pipe.

The specifications and operating conditions of this cooling tower are as follows:
It is. Cooling tower: CT-1 (Shinwa Sangyo SBC-80E)
S) Water holding volume: 1.2m³  Circulating water volume: 63m³/ Hr (80RT) Evaporated water volume: 650 L / hr Scattered water volume: 30 L / hr Blow water: 130 L / hr Residence time: 7 hours Makeup water: Atsugi city water Concentration magnification: 5 times

The hydrogen peroxide generator 35 is shown in FIG.
The specifications and operating conditions of each part are as follows.
Was. [Electrolyzer 1 for hydrogen peroxide production] Anode: Acid-resistant DSE electrode (Dimensionally Stable E
lectrode) (Permelec Electrode Co., Ltd.) Electrode area: 5dm²  Cation exchange membrane: Nafion 117 (manufactured by DuPont) Film thickness 0.3 mm Negative electrode: graphite powder having an average diameter of 7 μm (TGP-7 Tokai Ka)
And Polytetrafluoroethylene Disc
Load version 30J (Mitsui Fluorochemicals Co., Ltd.)
Mix in a volume ratio of 2: 1 and evaporate the solvent at room temperature.
After that, the mixture was processed into a sheet,
What was fired for a minute was used as a gas diffusion electrode,
The cathode is placed on top of the supply electrode plate consisting of 6 plates.
And [Dialysis tank 8] Cation exchange membrane: Nafion 117 (manufactured by DuPont) Membrane area 30 dm²  Flow path thickness: 0.5 mm each Flow path material: PTFE mesh [Operating conditions] Anolyte: 400 ppm NaCl aqueous solution Flow rate 2 L / hr Catholyte: Pure water Flow rate 2 L / hr Current: 15 A Voltage: 6 V Add to neutralization tank 12 NaOH concentration in the tank 14 to be changed: 10 N

When the hydrogen peroxide generator 35 was operated under the above conditions, the effluent of the dialysis tank (the effluent into the pipe 9a) of the anode effluent had an average acid concentration of 0.015N, which was necessary for neutralization. The amount of caustic soda is 0.24k / kg of hydrogen peroxide
g. The effluent of the cathode effluent from the dialysis tank 8 is:
The alkali / hydrogen peroxide molar ratio was 0.2, the hydrogen peroxide concentration was 2500 ppm, and the outflow was 2 L / hr.

From the hydrogen peroxide generator 35, 2 L / hr
The hydrogen peroxide aqueous solution having a hydrogen peroxide concentration of 2500 ppm, which is supplied in a fixed amount, is stored in the hydrogen peroxide injector 37, and 48 L of the hydrogen peroxide aqueous solution in the hydrogen peroxide injector 37 is discharged once a day.
The cooling water was injected into the feed pipe 32 at a frequency of times.

At this time, the slime adhesion amount, LTD (dirt index) and corrosion rate were examined by the following methods.
It was shown to. [Slime adhesion amount] After operation for 41 days, inner diameter 16 mm,
The adhering matter adhering to the inner surface of the SUS short tube 39 having a length of 301 mm is scraped off, and the suspension The mixture was filtered through a 5C filter paper, and the amount of the deposit was determined as the SS amount. [LTD (dirt index)] LTD (Leaving Temperature)
Difference) is obtained by correcting the temperature difference between the refrigerant condensation temperature in the refrigerator condenser in the heat exchange section and the cooling water outlet temperature by the following equation. Since the LTD becomes larger when dirt adheres to the condenser tube, the LTD is used as an index indicating the dirt adhesion state.

[0051]

(Equation 1)

The refrigerant used was Freon "R11", and the condensation temperature was determined from the discharge pressure. Further, the rated cooling water inlet / outlet temperature difference was 5.5 ° C., and the LTD after 41 days of operation was determined. [Corrosion rate] Copper piece 40A in short pipe 40 after operation for 41 days
Was examined for corrosion weight loss (mg), and the corrosion rate per day (100 cm ² ) (mdd) was calculated.

Example 2 The amount of water supplied to the hydrogen peroxide generator 35 was set to be 10 times that of the first embodiment, and the hydrogen peroxide generator 35 provided a hydrogen peroxide concentration of 2500.
Example 1 except that 20 L / hr of a hydrogen peroxide aqueous solution of ppm was stored in a hydrogen peroxide input device 37 and 480 L was injected into the cooling water feed pipe 32 once a day. The operation was carried out in the same manner, and the slime adhesion amount, LTD (dirt index) and corrosion rate were similarly examined. The results are shown in Table 1.

Comparative Examples 1 and 2 In Examples 1 and 2, the hydrogen peroxide charging device 37 was not provided, and the 2500 ppm aqueous hydrogen peroxide solution from the hydrogen peroxide generator 35 was used at 2 L / hr (Comparative Example 1) or 20 L / hr. hr
The operation was performed in the same manner as in (Comparative Example 2) except that the cooling water was continuously injected into the feed pipe 32. Similarly, the slime adhesion amount, LTD (dirt index) and corrosion rate were examined, and the results are shown in Table 1. Was.

[0055]

[Table 1]

The following is clear from Table 1.

That is, in Comparative Examples 1 and 2 in which the aqueous hydrogen peroxide solution continuously produced by the hydrogen peroxide generator was continuously added to the circulating cooling water system as it was, the injection amount of the aqueous hydrogen peroxide solution was small. In Comparative Example 1, the effect of preventing the adhesion of slime and dirt is not sufficient, and in Comparative Example 2 in which the amount of the hydrogen peroxide solution injected is large, the effect of preventing the adhesion of slime and dirt is good, but there is a problem of pipe corrosion. .

On the other hand, in Examples 1 and 2 in which the aqueous hydrogen peroxide solution was stored in the hydrogen peroxide injector and intermittently injected,
Good slime and dirt adhesion preventing effects can be obtained without causing pipe corrosion.

[0059]

As described above in detail, according to the slime treatment apparatus and the slime treatment method of the present invention, hydrogen peroxide generated by electrolysis at the slime treatment site is intermittently supplied to the slime treatment system. Slime treatment can be performed effectively by adding slime.

In particular, according to the slime processing apparatus of the second aspect, hydrogen peroxide can be produced at low cost, and the processing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a hydrogen peroxide producing apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a hydrogen peroxide storage / addition unit according to the embodiment of the present invention.

FIG. 3 is a system diagram showing a circulating cooling water system in which a slime treatment experiment was performed in the example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrolysis tank 2 Cation exchange membrane 3 Anode chamber 4 Cathode chamber 5 Anode 6 Cathode 8 Dialysis tank 11 Cation exchange membrane 12 Neutralization tank 20 Tank 22 Siphon tube 23 Injection pipe 24 Floating 28 Electromagnetic valve 31 Cooling tower 33 Heat exchange part 35 Hydrogen peroxide generator 37 Hydrogen peroxide injector

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 1/50 550 C02F 1/50 550C 550D 560 560F B01D 61/46 B01D 61/46 61/58 61/58 C02F 1/46 C02F 1/46 Z 1/469 1/72 1/72 C25B 1/30 C25B 1/30 C02F 1/46 103 (72) Inventor Nobuhiro Oda 3-4-2 Nishishinjuku, Shinjuku-ku, Tokyo Kurita Water Industries Ltd. (72) Inventor Masaharu Uno 1145, Ishikawa, Fujisawa City, Kanagawa Prefecture B-102 (72) Inventor Shuhei Wakita 5-5-9, Tsujido Motomachi, Fujisawa City, Kanagawa Prefecture II-3 F-term (reference) 4D006 GA17 JA42A JA42C KA03 KA52 KA54 KA55 KA56 KD17 KE15Q KE18Q MA03 MC30 PB07 PB08 4D050 AA02 AA08 AA10 AA12 AB06 AB31 BB09 BC10 BD04 4D061 DA02 DA07 DA08 DB02 DB09 EA02 EA09 EB04 EB13 EB30 EB39 ED12 ED13 FA16 GC05 GC12 4K021 AB15 BA02 BB03 BB04 DB01 DB31 EA06

Claims (3)

[Claims] 1. A means for producing a hydrogen peroxide-containing liquid by electrolysis, a means for receiving and storing the hydrogen peroxide-containing liquid produced by the means, and a position of the hydrogen peroxide-containing liquid in the storage means. A means for intermittently adding a fixed amount to the slime treatment system. 2. The method according to claim 1, wherein the means for producing the hydrogen peroxide-containing liquid comprises: an electrolytic cell having an anode chamber and a cathode chamber; and a first chamber and a second chamber partitioned by a cation exchange membrane. A dialysis cell having an anode effluent flowing out of the anode chamber of the electrolytic cell is introduced into the first chamber, and a cathode effluent flowing out of the cathode chamber is introduced into the second chamber, A slime treatment apparatus, wherein alkali metal ions in the cathode effluent pass through the cation exchange membrane and migrate into the anode effluent. 3. A slime characterized by producing a hydrogen peroxide-containing liquid by electrolysis, storing the obtained hydrogen peroxide-containing liquid, and then intermittently adding a predetermined amount thereof to the slime treatment system. Processing method.