**2.6 Accumulation of biological fouling**

On a heat transfer surface the growth of biological materials results in biofouling. In this case biological micro and macro organisms are stick to the heat transfer surface. When microorganisms (e.g., algae, bacteria, molds etc.) and their products grow they form microbial fouling. Seaweeds, waterweeds, barnacles develop microbial fouling. These fouling may occur simultaneously. The growth of attached organisms is one of the common problems [15] in heat exchanger operation. Food processing industries, power plant condensers using seawater, etc. are experiencing biofouling.
