The attachment of microorganisms (bacteria, algae, and fungi) and macroorganisms (barnacles, sponges, fishes, seaweed, etc.) on heat-transfer surfaces where the cooling water is used in as drawn condition from river, lake, sea and coastal water, etc., is commonly referred to as biological fouling. On contact with heat-transfer surfaces, these organisms can attach and breed, sometimes completely clogging the fluid passages, as well as entrapping silt or other suspended solids and giving rise to deposit corrosion. Concentration of microorganisms in cooling-water systems may be relatively low before problems of biofouling are initiated. Corrosion due to biological attachment to heat transfer surfaces is known as microbiologically influenced corrosion.
The techniques that can be effective in controlling biological fouling include the following:
1. Select materials that posses good biocidal properties.
2. Mechanical cleaning techniques like upstream filtration, air bumping, back flushing, passing brushes, sponge rubber balls, grit coated rubber balls, and scrapers.
3. Chemical cleaning techniques that employ biocides such as chlorine, chlorine dioxide, bromine, ozone, surfactants, pH changes, and/or salt additions.
4. Thermal shock treatment by application of heat, or deslugging with steam or hot water.
5. Ultraviolet radiation.
Hi friends,
ReplyDeleteBiological fouling is the undesirable accumulation of microorganisms, plants, algae, and animals on wetted structures. Biofouling is especially economically significant on ships hulls where high levels of fouling can reduce the performance of the vessel and increase its fuel requirements. It is also found in almost all circumstances where water based liquids are in contact with other materials. Thanks a lot.....
Evaporative Cooling Tower