JPH0629163B2 - Underwater organism control agent and aquatic organism adherence prevention method - Google Patents

Description

TECHNICAL FIELD The present invention relates to prevention of adhesion of aquatic organisms such as seawater.

[Conventional technology]

A thermal power plant that uses a large amount of seawater as transient cooling water,
At steel mills, petrochemical industries, etc., seawater organisms such as barnacles, mussels, bryozoa, and other insects adhere to the cooling water channels and heat exchangers, causing clogging of pipes, lowering of seawater sampling, and cooling efficiency. May cause functional deterioration such as deterioration of the device, and may cause various troubles such as damage of the device.

Conventionally, in order to prevent damage due to these attached organisms,
Chlorine, formalin, organic tin compounds, organic sulfur compounds, etc. have been used, but there are concerns about problems such as the amount and effect of addition, and environmental damage such as cumulative toxicity to fish and residual toxicity.

For example, TBTO widely used in organotin compounds
With regard to (tributyltin oxide), regulations have begun to be conducted on the problem of toxicity, and the effect of the addition of a drug cannot be expected from the usable amount.

In addition, organic sulfur compounds commonly used today,
Chlorine is also inferior in terms of effectiveness, and there are problems such as concern about toxicity.

As an example, dimethyldithiocarbamate, which is widely used as an organic sulfur compound, is inferior to barnacles effectively, and chlorine-based agents such as sodium hypochlorite have an anti-adhesion effect, but when residual chlorine is regulated. Effectiveness issues arise. In addition, THM (trihalomethane) may be generated.

[Problems to be Solved by the Invention]

An object of the present invention is to provide an agent for controlling organisms adhering to water and a method for controlling it, which does not cause environmental damage such as cumulative toxicity and residual toxicity.

[Means for Solving the Problems]

The present invention relates to an agent for controlling aquatic organisms that adheres to water, which comprises chlorine dioxide or a chlorine dioxide generator as an active ingredient, and a method for preventing the attachment of aquatic organisms using the agent.

As described above, the present invention has an effective chlorine amount 2.6 times that of chlorine instead of chlorine, and by using a highly water-soluble chlorine dioxide or a chlorine dioxide generator, the amount of chemicals used is reduced and, in turn, toxicity is increased. THM (trihalomethane) with
It has succeeded in preventing biofouling in water such as the ocean while preventing the generation of

The amount of chlorine dioxide used relative to water is at least 0.015 ppm or more, preferably 1 ppm or more.

The control agent of the present invention comprises a) chlorine dioxide itself, b) a chlorine dioxide-generating compound or composition, and c) the above a) or b).
Can be supported on a suitable carrier and can be classified into three types.

Examples of the chlorine dioxide-generating compound include alkali metal chlorite, particularly sodium chlorite. The amount used as sodium chlorite is at least 0.025 ppm, preferably 2 ppm or more. Sodium chlorite generates chlorine dioxide by reacting the following various compounds.

(i) By adding strong acid 4NaClO ₂ + H ₂ SO ₄ → 2ClO ₂ + Na ₂ SO ₄ + NaClO ₃ + NaCl + H ₂ O 5NaClO ₂ + 2H ₂ SO ₄ → 4ClO ₂ + 2Na ₂ SO ₄ + NaCl + 2H ₂ O (when Cl ^{− is} present) (ii) By adding hypochlorous acid 2NaClO ₂ + NaClO + H ₂ O → 2ClO ₂ + NaCl + 2NaOH (iii) By adding an oxide (Example) 5NaClO ₂ + 4CH ₃ COOH → 4ClO ₂ + 4CH ₃ COONa + NaCl + 2H ₂ O 5NaClO ₂ + 4RCOOR ′ + 2H ₂ O → 4ClO ₂ + 4RCOONa + 4R′OH R, R ′ is, for example, alkyl or phenyl.

(iv) In the case of adding reducing agent (Example) NaClO ₂ + 2NaHSO ₃ → NaCl + 2NaHSO ₄ NaClO ₂ + 2Na ₂ SO ₃ → NaCl + 2Na ₂ SO ₄ After that, it is preferred that the reaction components come into contact as soon as possible. In addition, the order of addition is preferably such that sodium chlorite is added first, and then the additive component is added at a position within 10 m.

The composition of the present invention may include an aqueous solution of chlorine dioxide stabilized with a percarbonate, such as sodium percarbonate. When this aqueous solution is made acidic, chlorine dioxide is liberated.

Examples of the carrier include zeolite, diatomaceous earth, pumice stone, alumina activated carbon, silica gel, montmorillonite and the like. It is also possible to use gelatin, agar, PVA, etc. as a composition gelled with an aqueous solution of chlorine dioxide or a chlorine dioxide-generating compound.

It is considered that the first stage of the effective chlorine generation process of chlorine dioxide is an oxidation reaction, and it is considered that ClO ₂ ⁻ is instantaneously reacted and then ClO ₂ ⁻ is oxidized.

Next, the following tests were conducted in order to confirm the effectiveness of the control agent of the present invention.

〔Test method〕

The test was performed using Artemia larvae, which are said to have a relatively high correlation with biological activity in barnacles, which are the main animal species in seawater fouling organisms (Artemia scale method).

The Artemia reared larvae used in the test are floated with commercially available brine shrimp dried eggs in a 28 ° C thermostat with artificial seawater. Only one day after levitation, only the larvae that floated were separated into separate containers, and further tested using only the larvae that had been bred for one day. If you do not use the larvae, the error will increase.

100m in a 200m beaker so that the evaluation chemicals have a specified concentration
Adjust and put about 50 Artemia larvae in it,
The state was observed with the passage of time and the inhibition rate and lethality rate were calculated. Suppression rate is expressed as a percentage of the total number of deaths and deaths, and lethality rate is the exact rate of deaths. If Artemia generally dies, it will settle to the bottom, slimming,
The color becomes slightly whitish. If the change was not obvious, it was considered to have died unless stimulated with a thin glass rod and moved. In addition, after the last 24 hours, only those that were not clearly visible were taken out and checked for life or death with a microscope.

The results are shown in Table 1.

Example 1 Each drug was evaluated using a model water channel as shown in FIG. Seawater is supplied to the model waterway 1 by an underwater pump 2. Three
Is a medicine tank, and a predetermined amount of the stored medicine is supplied to the model waterway 1 by a chemical pump. Incidentally, 4 is a branch header.

Immerse a 10 × 20 cm vinyl-made adhering plate near the outlet side of this model waterway, pass seawater transiently at about 0.3 m / sec and inject each chemical with a predetermined amount of chemical pump and after 90 days have elapsed The amount of marine organisms attached was investigated. Table 2 shows the results of conversion of the adhered amount into the number per 1 m ² .

From the above results, with regard to the effect of preventing the adhesion of organisms in seawater, sodium chlorite alone shows the effect of the conventional treatment, but by activating sodium chlorite to chlorine dioxide, a remarkable effect can be obtained.

Example 2 Except that a retention tank was provided at the end of the model water channel for a retention time of 30 minutes, an adhering plate was immersed before and after that, and sodium chlorite and sodium hypochlorite were used in combination as the chemical agent. An adhesion test was conducted in the same manner. The results are shown in Table 3.

[Effect] (1) Compared with sodium hypochlorite, which is an effective chlorine generator, it is effective in a small amount.

Furthermore, there is no generation of trihalomethane and no environmental pollution.

(2) The reaction product is composed of only the ions present in seawater and has no residual or cumulative toxicity.

[Brief description of drawings]

FIG. 1 is for explaining one embodiment of the present invention.

Claims (2)

[Claims] 1. An agent for controlling aquatic organisms that adheres to water, which comprises chlorine dioxide or a chlorine dioxide generator added to the water of a transient cooling water system of seawater as an active ingredient. 2. A method for preventing adherence of aquatic organisms, which comprises adding sodium chlorite and sodium hypochlorite to the transient cooling water of seawater.