In Industrial Cooling Towers (CTs) & Sea Water Once through cooling water, biofouling is a major concern as they can have a crippling effect on cooling water circuits. Bio films are layers of bacterial colonies, which form saccharide or ‘sugar’ linkages between these colonies. This results in the formation of a film or slime layer on the substrate or any surface in the water circuit.
They utilise nutrients and other microbes present in water to propagate and increase in thickness. Biofilms are the result of evolution by microorganisms to survive in fast moving streams of water. They use the linkages to strongly adhere to any surface or substrate. The structure of these biofilms is referred to as “Woven Matrix Colony”. This makes their removal a major challenge in CTs.
The matrix is basically water. The microbes are dispersed in this matrix of water. Biofilms are made up of 85 to 95% water. The temperature and free nutrient availability in cooling towers make them ideal for biofilm growth. The protection afforded to the microbes by the slime allows for rapid multiplication in the numbers of bacterial colonies – causing the biofilm to increase in thickness, and it results in various problems in the cooling circuit.