What are the main components of bactericidal and algicidal agents used in power plants?
Biocides and algicides used in power plants are primarily employed to control the growth of microorganisms (such as bacteria, algae, and fungi) in cooling water systems, preventing the formation of biofilms, corrosion, and scaling in equipment such as cooling towers and heat exchangers. Their main components typically include the following categories:
1. Chlorine-based compounds
Chlorine dioxide (ClO₂): This has strong oxidizing properties and can effectively kill bacteria, algae, fungi, and other microorganisms. It is widely used for disinfection in cooling water systems. Chlorine dioxide does not form harmful chlorine residues when it decomposes in water, making it suitable for use in most power plants.
Sodium hypochlorite (NaOCl): Another common disinfectant with strong bactericidal properties, it effectively eliminates algae and bacteria. However, sodium hypochlorite has the drawback of producing chlorine gas and byproducts (such as trihalomethanes), necessitating strict control of usage quantities.
Chlorine (Cl₂): A common broad-spectrum bactericide, but its corrosive nature and environmental impact from byproduct generation require special attention during use.
2. Oxidizing disinfectants
Hydrogen peroxide (H₂O₂): A strong oxidizing agent that effectively kills microorganisms, including bacteria, algae, and fungi. Hydrogen peroxide decomposes into water and oxygen when it reacts with organic matter in water, leaving almost no residue in the environment, making it environmentally friendly.
Ozone (O₃): Ozone is a highly efficient oxidizing agent that can effectively kill bacteria and algae, but due to its instability and operational complexity, specialized equipment is typically required to generate and inject ozone.
3. Copper-based disinfectants
Copper ions (Cu²⁺): Copper is a potent biological inhibitor that can destroy the cell walls of algae and bacteria and interfere with their metabolic processes. It is commonly used to control algae growth, especially in environments with hard water or high mineral content.
4. Quaternary ammonium compounds
Quaternary ammonium salts (e.g., benzalkonium chloride, cetyl trimethyl ammonium chloride, etc.): Quaternary ammonium-based disinfectants can effectively eliminate bacteria and algae in water. These compounds have good residual efficacy, maintaining antimicrobial effects in water for extended periods, making them suitable for long-term microbial control.
5. Organic acids
Organic acids (such as acetic acid, oxalic acid, citric acid, etc.): These acidic substances inhibit microbial growth by lowering the pH of water. They are effective in controlling algae and are often used in combination with other disinfectants.
6. Polymer-based disinfectants
Polymeric biocides (e.g., polyquaternary ammonium salts): Some polymers have strong adsorption properties and can bind to the cell membranes of algae and bacteria, thereby achieving algicidal and bactericidal effects. These compounds are typically used for long-term control.
7. Phosphate-based compounds
Phosphates (e.g., polyphosphates): Polyphosphates have some bactericidal activity, primarily by inhibiting the growth of algae and bacteria to prevent their reproduction.
Common ingredients in algicide and bactericide brands:
Biocides (e.g., Mecre, Kaida, Bailitong, etc.): These products typically contain hydrogen peroxide, chlorine dioxide, quaternary ammonium salts, or copper-based compounds, offering broad-spectrum algicidal and bactericidal effects.
Main applications:
Cooling water systems: Used to prevent the proliferation of algae and bacteria in equipment such as cooling towers, condensers, heat exchangers, and cooling pools.
Circulating water systems: Prevent algae proliferation, fungal growth, reduce biofilm formation, and minimize scaling and corrosion.
Other equipment cleaning: Biocides are sometimes used to remove microbial and algal buildup in equipment and pipelines.
Summary:
Biocides and algicides used in power plants typically consist of chlorides, oxidizing chemicals (such as hydrogen peroxide and ozone), copper-based compounds, quaternary ammonium salts, polymers, and other components. These chemicals prevent the growth and reproduction of algae, bacteria, and other microorganisms in water systems by oxidizing, chelating, or destroying microbial cells, ensuring the efficiency of cooling water systems and the long-term operation of equipment.
