JP2000126781A - Method for estimating and preventing bacterial slime trouble - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate slime trouble beforehand and to prevent the same by a simple method without arranging an electrical/mechanical apparatus. SOLUTION: Bacterial slime trouble caused by that bacteria propagate in circulating water and slime originating from bacteria is bonded to the inside of a piping is estimated beforehand to be prevented. In this case, a slime forming factor such as negative colloid is detected by using a chemical method such as the coloration change of an indicator and a slime control agent is charged before slime trouble is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a bacterial slime disorder such as blockage of pipes and reduction of heat exchange efficiency due to slime derived from bacteria adhering to pipes in a circulation path of cooling water or the like. And a method for preventing such problems.

[0002]

2. Description of the Related Art In recent years, the standard of living has been improved,
As water consumption has increased dramatically due to development,
Reuse by circulating and recovering industrial water such as water, particularly cooling water, is frequently performed. However, in cooling water in which open circulation is frequently used through cooling towers, there is an opportunity to cause problems in the circulation system such as corrosion and blockage of pipes or a decrease in heat exchange rate due to various contaminants from the outside. As the concentration rate of the circulating water increases, the degree of the obstacle tends to increase.

[0003] The obstacles to the circulation system include, for example, scale (or sludge) obstacles that cause deposits such as inorganic salts in the circulation pipes, corrosion obstacles in which the circulation pipes are corroded, and viscous substances derived from microorganisms in the circulation pipes. A slime disorder to which a substance (hereinafter, referred to as “slime”) adheres.

[0004] Among these obstacles, scale obstacles and corrosion obstacles are caused by the concentration of chemical substances (for example, inorganic salts and the like) in the cooling water or by the mixing of the chemical substances from the outside into the cooling water. The cause is an increase in the concentration of chemicals in water. Therefore, it can be suppressed by taking measures to prevent an increase in the concentration of chemical substances, such as using soft water instead of hard water as the cooling water, or periodically changing the cooling water.

[0005] On the other hand, slime disorders are disorders caused by the propagation of microorganisms such as mold, algae, and bacteria, and thus cannot be suppressed only by the same methods as scale disorders and corrosion disorders. Therefore, in order to prevent slime damage, it is necessary to properly grasp and manage the generation of slime in the cooling water, and to appropriately take measures such as pouring a slime controlling agent having a bactericidal / algicidal effect into the cooling water. Become.

Conventionally, as a method of grasping the slime generation state in cooling water, a temperature measuring resistor (an element whose electric resistance increases due to a temperature rise) maintained at a higher temperature than circulating water is immersed in circulating water. (Japanese Patent Application Laid-Open No. Hei 9-96873). According to the detection device, the slime adheres to the resistance temperature detector, heat diffusion from the resistance temperature detector is inhibited, and the temperature of the resistance temperature detector itself increases, so that the electrical resistance of the resistance temperature detector increases. Increase. Therefore, the slime generation state can be grasped by detecting the increase in the electric resistance.

[0007] According to the above-described method, since the resistance temperature detector serving as a sensor can be easily miniaturized and does not require a large installation area, the detection device can be directly installed in the circulation path without installing a bypass path. . That is, it is a very excellent method in that the state of slime generation can be accurately detected and managed in actual circulating water.

[0008]

However, since the above-described method is a method of detecting a slime generation state by attaching slime to a resistance temperature detector, the following problems have arisen.

First, since slime cannot be detected unless slime actually adheres to the resistance temperature detector, slime generated in a portion of the circulating water system other than the resistance temperature detector cannot be detected. . Secondly, since slime cannot be detected unless the slime grows to such an extent that the temperature of the resistance thermometer rises, it takes time from the generation of slime to detection, and measures such as injection of a slime control agent after the fact are taken. I had to become a target. Third, the use of an electrical / mechanical detection device requires installation and operation costs, and requires regular maintenance and management of the device, such as cleaning of the detection unit. I couldn't say.

The present invention has been made in view of such problems of the related art, and an object thereof is to provide a simple method without installing electric and mechanical devices and the like. An object of the present invention is to predict a slime disorder in advance and further prevent the slime disorder.

[0011]

Means for Solving the Problems As a result of diligent studies by the present inventors, the present inventors have found that slime damage can be predicted in advance by detecting a slime-forming factor produced by bacteria during slime formation. I arrived.

That is, according to the present invention, there is provided a method for predicting bacterial slime damage caused by bacteria growing in circulating water and slime derived from the bacteria adhering to a pipe, comprising: A method for predicting bacterial slime damage is provided, wherein the factor is detected using a chemical method.

In the prediction method of the present invention, it is preferable to detect a negative colloid in the circulating water as a slime-forming factor, and to detect a negative colloid in the circulating water using a substance that changes color by the presence of the negative colloid as an indicator. Is more preferred.

According to the present invention, there is provided a bacterium comprising detecting a slime-forming factor using the method for predicting bacterial slime damage as described above, and adding a slime controlling agent before the slime damage occurs. A method for preventing sexual slime disorder is provided.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a method for predicting a bacterial slime disorder, which comprises detecting a slime-forming factor using a chemical method. According to this method, it is possible to predict a slime disorder in advance and to prevent the slime disorder in advance by a simple method without installing an electric / mechanical device or the like. Hereinafter, the present invention will be described in detail.

The prediction method of the present invention is a method for predicting, among slime disorders, particularly bacterial slime disorders. As described above, microorganisms that cause slime damage may be bacteria, fungi, algae, etc., but moldy slime does not occur unless the circulating water is in an extremely eutrophic state. Because the occurrence is limited to the site where algae can photosynthesize, it is relatively easy to find and treat.

[0017] On the other hand, bacterial slime occurs more frequently than other slimes, and is generated in hard-to-find sites such as thin tubes near the heat exchanger in the circulation path of the circulating water, resulting in blockage of piping. -It is easy to cause troubles such as a decrease in heat exchange rate. Therefore, it can be said that the method of the present invention is a very useful method for preventing slime damage.

In the present invention, a method for detecting a slime-forming factor is employed in order to predict slime damage in advance. Slime disorders are caused by the growth of bacteria in the circulating water, the bacteria producing some form factors, and the bacteria forming the slime by adhering to the inner wall of the pipe due to the form factors. This is because it is considered that a slime disorder is caused, and therefore, if the formation factor can be detected, generation of slime can be detected at a stage before the slime disorder is reached.

In the present invention, a method of detecting the slime-forming factor by a chemical method, that is, by a chemical reaction without using an electrical or mechanical method is employed. According to such a method, since there is no need to install electrical and mechanical devices, there is no need for installation and operation costs, and there is no need for maintenance and management of the devices. Since the slime is detected by the change, it is possible to detect the slime even if it does not occur near the detection sensor. In general, it can be said that the detection sensitivity of the chemical method is sharper than that of the electric / mechanical method.

In the present invention, the method for detecting the slime-forming factor is not particularly limited as long as it can be detected using a chemical method, but it is preferable to detect a negative colloid in circulating water. This is a method utilizing the property that slime forming factors form negative colloids in circulating water.

When detecting a negative colloid in circulating water, it is more preferable to detect, as an indicator, a substance that changes color due to the presence of the negative colloid. According to such a method, the slime disorder can be predicted in advance by an extremely simple method of dropping the indicator into the circulating water and confirming the discoloration of the indicator.

Specifically, toluidine blue (hereinafter, referred to as toluidine blue)
It is called "TB". ) Is preferably used as an indicator. TB is a basic blue pigment, but has the property of being immediately adsorbed and discoloring reddish purple when negative colloids (ie, acidic colloids) are present, and because the reaction is extremely sensitive, This is because even a small amount of negative colloid can be easily detected.

If the above-mentioned TB or an indicator having similar properties is used, it is possible not only to qualitatively detect the negative colloid in the circulating water but also to quantitatively detect it. As a quantitative detection method of negative colloid,
For example, colloid titration described in “Colloid titration method” (author: Ryoichi Chide, published by Nankodo Co., Ltd.) can be used.

When the above-mentioned colloid titration is applied to the present invention, the amount of negative colloid in circulating water can be quantified by the following method, for example. First, the indicator liquid TB is added to the circulating water serving as the test liquid and colored red-purple,
Next, a standard solution of a positive colloid is gradually dropped onto the colored test liquid, and the dropping is completed when TB changes from reddish purple to blue.

Since the discoloration point of TB is the neutralization point (equivalent point) between the positive colloid and the negative colloid, the amount of the negative colloid in the circulating water is converted from the drop amount of the standard colloid standard solution at the time of the discoloration. (Hereinafter, such a method is referred to as “direct titration”).

As a standard solution of the positive colloid, a colloid solution of a water-soluble substance which generates a positive charge by ionization of an amino group such as polyvinylbutylpyridinium bromide and polyethyleneimine can be used.
However, methyl glycol chitosan (hereinafter, referred to as "neutral") can be used in the entire pH range and has a precipitate at the neutralization point so that the neutralization point can be detected without an indicator. It is preferable to use an aqueous solution of a glycol chitosan derivative such as “MGch”.

In addition, a method in which an excess amount of a positive colloid standard solution is added to a negative colloid in circulating water to precipitate a negative colloid, and then the remaining excess positive colloid is titrated using the negative colloid standard solution. Similarly, it is possible to quantify the negative colloid. This method is generally called back titration (indirect titration), and can be used more preferably in that it can accurately measure even a weakly electrolytic colloid as compared with the direct titration described above.

As the standard solution of the negative colloid used in the back titration, a colloid solution of a water-soluble substance which generates a negative charge by ionization of a carboxyl group, a sulfate group, or the like can be used. It is preferable to use an aqueous solution of polyvinyl alcohol potassium sulfate (hereinafter, referred to as “PVSK”) because of its sharpness.

By using the method for predicting bacterial slime damage described above, it is possible to prevent slime damage in advance. Specifically, a slime-forming factor can be qualitatively detected in the circulating water, and a slime-controlling agent is added in advance to prevent the slime-forming agent from occurring.

Such a method can be expected to more efficiently prevent slime damage by quantifying the slime-forming factor and calculating the input amount of the slime-controlling agent from the amount of the slime-forming factor. As the slime controlling agent, there are various types such as chlorine type, quaternary ammonium salt type, quaternary phosphonium salt type, organic sulfur type, organic bromine type, organic nitrogen sulfur type, etc. Chlorine-based ones can be suitably used in terms of low processing cost, and other types can be suitably used in terms of low corrosiveness.

[0031]

Hereinafter, the slime disorder prediction method of the present invention will be described in more detail. In Examples, the detection of the slime-forming factor was carried out by the following qualitative test and quantitative test. 0.1 (w / v)% T as indicator
B aqueous solution is 0.005N as a standard colloid standard solution.
The MGch aqueous solution of
A 0.0025N PVSK aqueous solution was used.

(Qualitative test) One drop of a TB indicator was added to the test solution, and the coloring was observed. The color of the TB was determined to be positive if the blue color of the TB turned red, and negative if the blue color of the TB was retained. If it was positive, it was judged that a negative colloid (ie, slime forming factor) was present, and if it was negative, it was judged that it was not qualitatively present (if it was present, it was very small). It is preferable that the amount of TB added be small as long as the color can be determined. This is because a positive reaction may be difficult to confirm due to excessive TB.

(Quantitative test) If the above qualitative test is positive, the test solution is measured in a 20 ml Erlenmeyer flask or the like, and while stirring with a stirrer, 1 drop of TB indicator and 1 ml of MGch standard solution are added. Observe the color of the test solution.

When the test liquid is colored blue, the positive colloid of MGch is in excess of the negative colloid in the test liquid. Therefore, the excess amount of the positive colloid is back titrated by dropping the negative colloid PVSK standard solution, the drop amount (ml) at the time when the red colloid is recorded, and the negative colloid concentration is calculated from the drop amount. According to this method, quantification is possible if the negative colloid is present at a concentration of at least 5 μmol / l.

The negative colloid concentration (μmol / l) can be calculated by the following equation (1). {(Fm × Cm × Vm) − (fp × Cp × Vp)} × 1000 / sample amount × 1000 (1) (however, fm: the factor of the MGch standard solution, Cm: M
Gch standard solution concentration (mol / l), Vm: volume (ml) of MGch standard solution added to test solution, fp: PV
SK standard solution factor, Cp: concentration of PVSK standard solution (mol / l), Vp: PVSK added to test solution
Standard solution volume (ml). )

The negative colloid concentration is low and PVSK
If the amount of the standard solution dropped is extremely small, a titration error may occur. In such a case, the more sparse P
By using a VSK standard solution and increasing the amount of dropping, accurate titration can be performed.

On the other hand, when the test liquid has already been colored red-purple at the time of adding the TB indicator, the negative colloid in the test liquid is in excess of the added positive colloid of MGch. . Therefore, the MGch standard solution was further dropped, and the dropping amount (ml) at the time of blue discoloration was recorded, and then 1 ml of the MGch standard solution was added similarly to the case where the test solution was colored blue, and PVSK was added. Perform a back titration with a standard solution.

When the qualitative test is negative, the amount of the negative colloid is extremely small, and it is difficult to detect by the above-mentioned method. However, after performing the following centrifugal concentration treatment, the titration is performed by the above-mentioned method. For example, negative colloids can be quantified as in the case where the qualitative test is positive.

15 ml of the test solution is measured into a membrane filter for centrifugal filtration (for 15 ml, having a cut-off molecular weight of 10,000, for example, Ultrafree 15 (manufactured by Millipore)), and centrifuged at 2000 G for 15 minutes. Perform separation.

The precipitate generated by the centrifugation is made up with distilled water to a total volume of 0.5 ml to prepare a concentrated solution (the concentrated solution is initially 30% of the test solution).
This means that it has been concentrated twice). When a drop of the TB indicator is dropped on the entire amount of the concentrated solution and the solution is colored reddish purple, the quantitative test is performed by the same operation as the quantitative test described above. On the other hand, when the blue color is maintained even when the TB indicator is dropped on the concentrate (ie,
Negative), it was judged that there was no negative colloid.

Before applying the method of the present invention to an actual circulating water system, slime-forming factors were extracted from existing slime, and it was evaluated whether the above-mentioned TB color reaction could be applied to the detection of slime-forming factors. .

First, slime-forming factors were extracted from existing slime by the following method. Slime adhering to a water pipe of a certain factory was collected, suspended in sterilized water, and the suspension was added to a normal agar medium (1/1) having the composition shown in Table 1.
(10 densities). The cells were cultured at a temperature of 30 ° C. for 24 to 48 hours, and the appeared colonies were separated.
saved.

[0043]

[Table 1]

The above-mentioned isolated bacteria were inoculated in 200 ml of a liquid medium containing 0.8% of nutrient broth and 0.1% of yeast extract, and cultured with shaking at 37 ° C. for 24 hours.
Centrifugation was performed at 5000 rpm for 15 minutes at 4 ° C.

Since the slime forming factor is presumed to be a macromolecule such as an acidic polysaccharide produced by bacteria, it is considered that the slime forming factor is precipitated by isopropyl alcohol having a strong dehydrating power. Therefore, after centrifugation, one volume of the supernatant from which the precipitated portion (cells) was removed was added to isopropyl alcohol (hereinafter referred to as “IPA”).
That. ) Was added in two volumes and shaken vigorously for 10 minutes.

After shaking, at 4 ° C., 10,000 r
After centrifugation at pm for 30 minutes, the supernatant was discarded and the precipitate was collected (hereinafter, referred to as “IPA precipitate”). In addition, a precipitate obtained by performing the same operation without inoculating the liquid culture medium with the isolate (hereinafter, referred to as “medium precipitate”) was also prepared as a control.

Next, the adhesion of the bacteria to the metal plate in the presence of the IPA precipitate was observed, and the correlation with the slime formation was confirmed. A piece of stainless steel
100 mg of PA precipitate (or medium precipitate) in distilled water 1
After the suspension was suspended in 00 ml or immersed in distilled water and taken out, the metal piece was further added to a suspension in which the adherent bacteria whose cell surfaces had been washed with physiological saline were suspended in physiological saline. Dipped and removed.

After the surface of the metal piece was washed lightly with physiological saline, it was placed on a petri dish, overlaid with an agar medium containing 0.8% nutrient broth, and cultured at 36 ° C. for 24 hours. The state of adhesion was observed. As a result, as shown in Table 2, bacterial adhesion was observed only on the metal pieces immersed in the IPA precipitate suspension, and it was confirmed that the IPA precipitate was a slime-forming factor.

[0049]

[Table 2]

When a qualitative test of TB coloration was performed on the IPA precipitate suspension, the medium precipitate suspension, and distilled water, only the IPA precipitate suspension was positive as shown in Table 2. Was. Therefore, it was confirmed that the TB color reaction can be applied to the detection of a slime-forming factor.

Example 1 Various kinds of circulating water having different slime conditions were collected in a cooling water system actually operating, and whether or not there was a correlation between the slime condition and the amount of negative colloid in the quantitative test. It was confirmed.

As a result, as shown in Table 3, a correlation was observed between the amount of PVSK dropped and the amount of slime in the quantitative test. Further, as shown in Table 3, the TB color reaction was negative for non-bacterial slimes (moulds and algae-based slimes). Therefore, the method of the present invention specifically detected only bacterial slimes. It was confirmed that it was a way to obtain.

The amount of slime was evaluated qualitatively based on the state of slime adhered to a cooling resin corrugated sheet (hereinafter referred to as “filler”) arranged at intervals of 5 to 10 mm in the actual cooling tower. went. That is, slime was not visually observed on the filler, and slime was not felt even if touched, but slime was not visually observed,
Those that felt slimy when touched were evaluated as "less", and those where slime was clearly visually observed were evaluated as "high".

[0054]

[Table 3]

Example 2 A model circulating cooling water system 1 as shown in FIG. 1 was continuously operated for 24 hours, and the relationship between the amount of negative colloid in the cooling water and the slime adhered to a pipe was investigated. The model circulation cooling water system 1 is configured by connecting a cooling tower 2, a holding water tank 3, a circulation pump 4, and a heat exchanger 5 via a pipe 6. The cooling tower 2 includes a cooling fan 2a, a filler 2
b so that water can always be supplied by the supply pump 7.

A part of the outlet pipe 6a of the heat exchanger was formed of a transparent vinyl chloride pipe, and was used as a looking 6b for observing a slime adhesion state in the pipe. In addition,
The operating conditions of the model circulating cooling water system 1 were such that the refrigerating capacity was 3 refrigeration tons, the retained water amount was 100 l, the circulating water amount was 30 l / min, and the makeup water amount was 0.3 l / min.

Evaluation of the amount of slime in Example 2
It is performed by visually observing the looks 6b of the heat exchanger outlet pipe 6a, and “none” indicates that no slime is observed in the looks 6b, and “less” indicates that the slime is adhered to the looks 6b but the opposite side can be seen through. And the case where the looking 6b was covered with slime and the opposite side could not be seen through was evaluated as "many".

As a result, as shown in Table 4, the color reaction of TB was positive even at the stage of the 8th day of operation where slime could not be confirmed by visual judgment of the looking 6b,
The occurrence of slime has been detected. That is, according to the method of the present invention, it was confirmed that slime damage can be predicted at an early stage of the generation, at which slime generation is invisible. Further, when glutaraldehyde was added at a concentration of 200 mg / l as a slime controlling agent, it was confirmed that the negative colloid which is a slime-forming factor disappeared and the amount of slime attached was reduced.

[0059]

[Table 4]

[0060]

As described above, since the predicting method of the present invention detects a bacterial slime-forming factor by a chemical method, it is possible to predict a slime disorder in advance. Further, if the slime-forming factor is detected by a color reaction of the indicator or the like, it is not necessary to install an electric / mechanical device or the like, and it is possible to easily predict a slime disorder. Furthermore, by using the prediction method of the present invention,
Since the slime-forming factor in the circulating water can be qualitatively detected and the slime controlling agent can be added in advance, it is possible to prevent slime damage beforehand.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a model circulation cooling water system used in Example 2.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Model circulation cooling water system, 2 ... Cooling tower (2a ... Cooling fan, 2b ... Filling material), 3 ... Water tank, 4 ... Circulation pump, 5 ... Heat exchanger, 6 ... Piping (6a ... Heat exchange) Outlet piping, 6b: Looking), 7: Replenishing pump.

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Claims (4)

[Claims] 1. A method for predicting bacterial slime damage caused by bacteria growing in circulating water and slime derived from the bacteria adhering to pipes, wherein a slime-forming factor is analyzed by a chemical method. A method for predicting bacterial slime damage, wherein the method is used for detection. 2. The method for predicting bacterial slime damage according to claim 1, wherein a negative colloid in circulating water is detected as the slime-forming factor. 3. The method for predicting bacterial slime damage according to claim 2, wherein the negative colloid in the circulating water is detected using a substance that changes color due to the presence of the negative colloid as an indicator. 4. A method for detecting a slime-forming factor using the method for predicting bacterial slime damage according to any one of claims 1 to 3, and adding a slime controlling agent before slime damage occurs. A method for preventing bacterial slime disorders, which is characterized by the following.