Biofouling and Cooling Water Systems

The industrial cooling water systems provide an ideal medium (32-38 oC in the water temperature and 8-9 in pH) for biofouling. The water source contains all the naturally occurring living organisms and nutrients that are responsible for uncontrolled multiplication of the living organisms. Apart from biofouling, the biological growth plays an important role in promoting corrosion through the formation of acid metabolic products resulting in corrosion damage to the heat transfer and other process equipments.

Biofouling has been recognized as an important contributor to impaired heat transfer causing decrease in efficiency and increased power consumption. In fact, it has been unequivocally demonstrated that because of the unique surface characteristics of bio-films, their hydrodynamic and insulating properties far exceed those of an equivalent thickness of inorganic scales or corrosion deposits. Biofouling can also destroy cooling tower lumber. More seriously, such contaminants can be harmful to humans coming in contact like operational and maintenance personnel. The most notable example has been the outbreaks of Legionnaires' disease, affecting people in hotels, hospitals, office buildings, and other locations, who have come into contact with cooled air from an air conditioning system contaminated from cooling tower water of the air conditioning plant.

What is Biofouling?

Biofouling is the growth of living organisms like bacteria, algae and fungi on the surface in contact with the water for a period of time. Biofouling is a complex process and begins with the formation of a thin layer of micro organisms on the solid surface when conditions such as pH, temperature and availability of the nutrients are right. A number of organisms including bacteria, protozoa, amoebae, fungi, barnacles and other organisms have been shown to form bio-films that create nuisances in man-made environments after the equipment functioning. The growth of a bio-film can progress to a point where it provides a foundation for the growth of seaweed, barnacles, and other organisms. Bio-films occur and are a problem in the water service utilities, many industrial processes including the food, pharmaceutical, paint, oil processing and manufacturing, and engineering industries using water either in the process (chemical, pharmaceutical and food) or as a utility (cooling, lubrication etc). Power generation stations are frequent targets of fouling invertebrates, including zebra mussels, colonial hydroids, bryozoans, and sponges. An optimal combination of abundant food, warm temperatures, flowing water can result in serious growths in the intake chambers, filters, condenser tube sheets, and other structures. While the populations may die off seasonally, they leave behind dormant reproductive bodies capable of producing a new, larger generation when conditions are favorable.

More information on Biofouling:

• Biofouling: Why, Where and When?

• Biology of Cooling Waters

• Steps in Biofilm Formation

• Our solution : HyCator™: BFP for prevention of Biofouling