Why is microbiological growth a problem in cooling systems?

Microbiological growth can cause fouling in a cooling water system as well as pose a health risk. Algae and bacteria that form sessile deposits can cause under deposit corrosion leading to tube failure. The deposits are also capable of blocking off water flow reducing the efficiency of the cooling system. Bacteria are especially a health hazard in cooling systems as these operate at human body temperature making them an ideal incubator for waterborne human pathogen e.g. Legionella.
There two ways to minimize organic growth:
1. Electric antifouling systems consisting of a number of anodes and cathodes immersed in the cooling water flow. The electrical potential between electrodes kills bacterial and micro shellfishes.
2. Biocide programmes. Specially designed chemicals dosed into the cooling system to keep growth under control.