food grade product line by Water Services Ltd

Conditions in a typical industrial or electric power plant cooling water systems are close to ideal medium for biological and marine growth like living organism referred to as Biofouling. This cooling water system provides an ideal medium (32-38 ^oC in the water temperature and 8-9 in pH) for the biological growth because it provides air, heat and light. The water source contains all the naturally occurring organisms and nutrients that are required for biological growth. Also inorganic and organic phosphates are often used for corrosion control, thus adding additional nutrients. This requires, above all, a clean heat exchanger and heat transfer and cooling efficiency.

There is no need to emphasize the fact that algae proliferate in the cooling towers and basins open to the air, particularly in summer. In a recirculating system, the water in the tower is cooled by evaporation and thereby becomes more concentrated with dissolved solids, since biofouling often serves as the "glue" that binds other deposits to the heat transfer surfaces. If the main purpose of a cooling tower is to cool the discharge water, concentration cycles will be low. If the purpose is to conserve water and reduce discharge water volume, the water will be held in the system much longer and become more concentrated with dissolved solids, thus increasing the fouling potential.

For biofouling control, to kill the algae and slime type growths, to keep the plant cooling water pipework clear of growths to attain maximum heat transfer efficiency, the chlorine gas is generally added at the circulating pump suctions or water intake screens of a recirculating cooling tower system. Also the object of chlorinating cooling water is to kill the water borne organisms before they have a chance to attach themselves to the internals of the cooling system and block the water flow, reducing the cooling efficiency.

Once the growth is established to a degree that it reduces the cooling efficiency, chlorination will not remove the growth; the only solution is to mechanically clean the system then chlorination will keep it clean by killing the organisms before they attach themselves to the internal of the cooling system.

The classes of microbiological organisms that proliferate in open recirculating cooling systems are Algae, Fungi and Bacteria.