JP5596106B2 - Amoeba suppression method - Google Patents

Description

The present invention relates amoeba suppression method using the amoeba killing agent to kill the amoeba aqueous water amoeba in circulating cooling water of the refrigeration system or air-conditioning facility is inhabited.

  Legionella spp. That survive in water systems are known as pathogens for Legionella disease, but they can breed in circulating cooling water in air conditioning facilities and cause problems such as sending out large numbers of infected people at once through air conditioning equipment. Various methods have been proposed for the sterilization.

  However, even in the case of a drug having a sufficient effect in laboratory experiments against these Legionella spp., A sufficient effect is not always obtained in an actual aqueous system.

  After examining in detail the difference in efficacy between the laboratory and the actual environmental water system, it has been found that in the actual environmental water system, it is indispensable to sterilize Legionella spp. .

  Until now, Legionella was known to parasitize and multiply in predatory protozoa, such as amoeba, in the actual environmental water, but the conventional eradication technology of Legionella is the growth of Legionella. The problem was that it did not focus on the ecological characteristics of the.

  That is, as a result of detailed studies, it was found that Legionella spp. Can survive and proliferate in the presence of amoeba even in an environment where it cannot survive by itself.

  Here, considering the case where a fungicide for Legionella is added to an aqueous system in which Legionella and amoeba are suitably grown, if the fungicide does not affect the growth of Amoeba, Because it is active normally, it prey on Legionella spp. With a certain probability. Legionella genus preyed on by amoeba grows in the body without being affected by the fungicide in the water system and is not digested by amoeba. It bursts and comes out into the water system. Legionella spp. That have entered the water system gradually die out by being exposed to a fungicide, but Legionella spp. That have been preyed on by amoeba before they die will grow again in the body of amoeba.

  Therefore, in order to effectively sterilize Legionella spp. In such an aqueous system, it is necessary to suppress amoeba itself, which is a place for growth of Legionella spp. Examples of the amoeba serving as a host of such Legionella genus include Acanthamoeba, Naegleria, Hartmannella, Vannella and the like.

  In addition, amoeba has recently become a host of Legionella spp. (See Japanese Patent Application Laid-Open No. 11-57737 (Patent Document 1)), but it also enters the brain nasally and is highly lethal meningoencephalitis It has become known to have pathogenicity, such as causing keratitis in contact lens users. Here, Acanthamoeba, Negrelia and Balamthia are known as amoeba causing meningoencephalitis, and Acanthamoeba is known as amoeba causing keratitis, respectively.

  Amoeba that can cause various problems in this way lives in rivers, lakes, ponds, etc., or in artificial environment water such as circulating cooling water systems and circulating baths of air conditioning equipment such as buildings.

  With respect to such an amoeba, the present inventors have proposed a disinfectant according to Japanese Patent Application Laid-Open No. 2002-308713 (Patent Document 2). According to this proposed technique, although a high amoeba killing effect can be obtained, there are some inconvenient parts such as intense foaming in actual application to aquatic water.

JP-A-11-57737 JP 2002-308713 A JP-A-5-331002 Japanese Patent Laid-Open No. 10-45514

The present invention provides an amoeba suppression method using an amoeba killing agent that improves the above-described conventional problems, that is, has no foaming property and can reliably obtain high effects even in actual aqueous water. Objective.

In order to solve the above-mentioned problem, the method for suppressing the amoeba of the circulating cooling water according to the present invention provides 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl as the isothiazoline-based compound as described in claim 1 -4-Isothiazoline-3-one and two or more cationic polymers such as poly [oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride], poly (hexamethylenebiguanide) or salts thereof Amoeba inhabiting an amoeba fungicide containing, as active ingredients, one or more of condensation polymers of dimethylamine and epichlorohydrin and 2-bromo-2-nitropropane-1,3-diol It is the amoeba suppression method of circulating cooling water characterized by adding to the circulating cooling water .

Moreover, the amoeba suppression method of the circulating cooling water of this invention is that the said cationic polymer is poly [oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride] as described in Claim 2. It is the amoeba suppression method of the circulating cooling water of Claim 1 characterized by the above-mentioned.

  The amoeba disinfectant of the present invention is an amoeba disinfectant that does not have foaming properties and can reliably obtain a high effect even in actual aqueous water.

  The present invention contains an isothiazoline compound and a cationic polymer as active ingredients. At this time, a high synergistic effect that cannot be obtained by using these isothiazoline compounds and cationic polymers alone is obtained, and a high amoeba killing effect can be obtained even at a low concentration.

  It is known that isothiazoline compounds are low toxicity drugs. The isothiazoline compounds used in the present invention include 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 1,2-benzisothiazoline-3-one, 2 -N-octyl-4-isothiazolin-3-one etc. are mentioned, Among these, 1 type or 2 types or more are selected and used. Here, particularly preferred isothiazoline compounds include 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one.

  On the other hand, a cationic polymer is a low-toxic chemical and is used as an algicide by JP-A-5-331002 (Patent Document 3) or JP-A-10-45514 (Patent Document 4). As is known, it is not enough to kill or suppress amoeba alone.

  Examples of the cationic polymer used in the present invention include poly [oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride], poly (hexamethylenebiguanide) or a salt thereof, a condensation polymer of dimethylamine and epichlorohydrin, and the like. Of these, one type or two or more types are selected and used. Here, as a particularly preferred cationic polymer, poly [oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride] can be mentioned.

  The blending ratio of these isothiazoline compounds and cationic polymers is preferably 10: 1 to 1: 100 (including the boundary value) in terms of the weight ratio of the active ingredients, because it provides a high effect. ˜1: 20 (including the boundary value) is preferable because a particularly high effect is obtained. Here, these two drugs are dissolved in water and are stable as one drug.

  In the present invention, the isothiazoline-based compound and the cationic polymer are 0.1 mg / L or more and 1000 mg / L or less, more preferably 1 mg / L or less as a total addition concentration of active ingredients with respect to aqueous water for the purpose of killing or suppressing amoeba. L is added so as to be 100 mg / L or more.

  The amoeba fungicide of the present invention is, for example, acrylic acid-based, maleic acid-based, methacrylic acid-based, sulfonic acid-based, itaconic acid-based, as long as the effects of the present invention are not impaired for the purpose of improving its properties. Or scale inhibitors such as isobutylene polymers and copolymers thereof, phosphoric acid polymers, phosphonic acid, phosphinic acid, or water-soluble salts thereof, for example, aldehydes such as glutaraldehyde and phthalaldehyde , Hydrogen peroxide, hydrazine, chlorine-based disinfectants (such as sodium hypochlorite), bromine-based and iodine-based disinfectants, dithiol-based compounds, thiocyanate-based compounds such as methylenebisthiocyanate, pyrithione-based compounds, quaternary Non-polymer cationic compounds such as ammonium salt compounds and quaternary phosphonium chlorine compounds Anti-lime agents such as azoles such as benzotriazole and tolyltriazole, amine compounds such as ethylenediamine and diethylenetriamine, and aminocarboxylic acid compounds such as nitrilotriacetic acid, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, such as gluconic acid, Various water treatment agents such as organic carboxylic acids such as acid, oxalic acid, formic acid, tartaric acid, phytic acid, succinic acid, and lactic acid can be used in combination, and such cases are also included in the present invention.

  As such, when 2-bromo-2-nitropropane-1,3-diol is added to the amoeba killing agent of the present invention, the control effect on bacteria such as Legionella spp. Is also particularly preferable.

  The amoeba-suppressing method of the present invention is performed by adding an amoeba-killing agent as described above to aqueous water. In this case, the amoeba-suppressing agent is added to aqueous water that is not detected by amoeba to prevent the amoeba. In addition, it may be added to the aquatic water where the amoeba already lives to suppress the amoeba.

  Examples of the amoeba fungicide of the present invention will be specifically described below.

(Preparation of E. coli-coated agar medium)
Agar for bacterial testing is dissolved in ion-exchanged water so that the concentration is 1.5% (w / v), sterilized at 121 ° C. for 15 minutes, and then dispensed in a sterile petri dish with a diameter of 90 mm to 15-20 mL. Was made. Next, an appropriate amount of E. coli cultured separately on a standard agar plate medium is collected and suspended in sterilized ion-exchanged water to prepare a concentrated E. coli suspension, which is heat-treated at 60 ° C. for 1 hour, and then sterilized. It diluted with ion exchange water so that OD600 might be set to 0.5. Then, 0.3 mL of this solution was applied to the entire surface of the agar plate and dried to such an extent that Escherichia coli was fixed on the surface of the agar, thereby preparing an Escherichia coli-coated agar medium.

<Example 1>
A sample obtained by adding 1.2 × 10 ⁴ nutrients of Acanthamoeba 96 cultured for 2 days using the E. coli-coated agar medium prepared above to sterile tap water was used as test water.

  10 mL of this test water was put into a tissue culture flask, and chemicals indicated by abbreviations in Table 1 were added so that their active ingredients had concentrations shown in Table 2, and then allowed to stand at 28 ° C. One day after the addition of the chemical, a part of the test water is sampled and serially diluted as necessary. Then, 1 mL of the test water is applied to an E. coli-coated agar medium, cultured at 28 ° C. for 7 days, and the number of plaques generated on the medium is determined. The number of surviving amoeba was examined by counting. The results are shown in Table 2. In addition, “<1” in the table indicates a detection lower limit (1 piece / mL).

<Example 2>
The active component concentration of CMI in the cooling water is 0.5 mg / L and the effective component concentration of PO is 5 mg with respect to the untreated cooling water system water (number of amoeba: 1500/100 mL or more) that is actually operating. Amoeba suppression treatment was performed so as to maintain each / L. The number of amoeba one day after the start of the treatment was less than 2/100 mL, and it was less than 2/100 mL even one week after the start of the treatment. In addition, measurement of the number of amoeba in cooling water is described in pages 95-98 of the new edition Legionellosis Prevention Guidelines (supervised by the Ministry of Health and Welfare, Health Sanitation Bureau Planning Division, Publisher: Building Management Education Center, November 1999, first edition) (The same applies hereinafter).

<Example 3>
Treatment method for cooling water system water actually used for cooling (number of amoeba: 8800/100 mL) that controls microorganisms by maintaining the active ingredient concentration of CMI in cooling water at 5 mg / L The amoeba suppression treatment was performed so that the active ingredient concentration of CMI in the cooling water was maintained at 1 mg / L and the active ingredient concentration of PO was 20 mg / L. The number of amoeba one day after the start of the treatment was less than 2/100 mL, and it was less than 2/100 mL even one week after the start of the treatment.

<Example 4>
Treatment of cooling water system water for cooling that is actually operating (amoeba number: 10000/100 mL or more) that controls microorganisms by maintaining the active ingredient concentration of PO in cooling water at 25 mg / L Amoeba suppression treatment is performed by changing the method and adding chemicals once a day so that the active ingredient concentration of CMI is 2 mg / L and the active ingredient concentration of PO is 20 mg / L with respect to the retained water. It was. The number of amoeba one week after the start of the treatment was less than 2/100 mL, and it was less than 2/100 mL even one month after the start of the treatment.

Claims (2)

As an isothiazoline-based compound, one or two of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one, and as a cationic polymer, poly [oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride], poly (hexamethylene biguanide) or a salt thereof, killing amoeba containing one condensation polymer of dimethylamine with epichlorohydrin, or a two or more as an active ingredient A disinfectant,
2-bromo-2-nitropropane-1,3-diol,
Is added to the circulating cooling water inhabiting the amoeba. The method of suppressing amoeba of circulating cooling water according to claim 1, wherein the cationic polymer is poly [oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride] .