Biocides

Biocides for cooling towers are chemicals used to control the growth of microorganisms such as bacteria, fungi, and algae in water cooling systems. In a cooling tower, water circulates constantly, creating warm and humid conditions that are ideal for microbial growth. If not controlled, microbes can cause:

• Biofilm → a layer of slime that sticks to the surface of pipes/towers, reducing heat transfer efficiency.

• Microbiological corrosion → material deterioration due to microbial activity.

• Blockage of water flow → algae and mold can block circulation paths.

• Health risks → e.g. Legionella growth which can lead to legionellosis.

Types of biocides

1. Oxidizing biocides

   • Examples: chlorine, bromine, sodium hypochlorite.

   • Mode of action: oxidizes the cell walls of microorganisms so that the cells die.

   • Suitable for routine use in controlled doses.

2. Non-oxidizing biocides

   • Examples: isothiazoline, glutaraldehyde, DBNPA.

   • Mode of action: damages microbial metabolism or cell structure.

   • Effective against oxidizer-resistant microbes.

How to use

• Usually applied by regular dosing (continuous or periodic).

• Dosage is determined based on water quality (pH, TDS, microbial load).

• Monitoring is done by microbiological tests, ORP measurements (for oxidizing), or other chemical methods.

Main Objective

• Maintain the efficiency of the cooling system.

• Reduce maintenance costs due to fouling or damage.

• Ensure the health safety of the work environment.