Fouling

Fouling is the accumulation of unwanted material on solid surfaces that are in contact with a liquid or gas, leading to degraded performance. It is commonly categorized into biofouling, inorganic fouling, and organic fouling. Biofouling begins with the adsorption of an organic conditioning film, followed by microbial attachment and growth that forms biofilms and, over time, larger organisms. Inorganic fouling, often called scaling, consists of mineral deposits such as calcium carbonate, calcium sulfate, or silica. Organic fouling involves non-biological organic residues, polymers, or oils that adsorb and accumulate on surfaces.

Fouling occurs in a variety of settings, including ships’ hulls, heat exchangers, filtration membranes, and process piping. The specific mechanisms depend on fouling type but generally involve deposition, growth, and adhesion under the influence of flow, temperature, chemistry, and surface properties.

Impacts include increased fluid friction, reduced heat transfer, higher energy consumption, clogging, and the need for more frequent cleaning or maintenance. Biofouling can also alter surface chemistry and corrosion behavior, complicating material selection and design choices.

Prevention and control rely on design choices and operational practices such as anti-fouling coatings (biocidal or fouling-release), periodic mechanical cleaning, chemical cleaning to remove deposits, water treatment to control scale and microorganisms, filtration to remove particulates, and, in some cases, ultrasonic or other non-destructive cleaning methods. Environmental concerns lead to regulatory restrictions on certain biocidal coatings.

Fouling is a major concern in industries such as maritime transport, power generation, and water treatment, driving research into surface engineering, cleaning technologies, and process optimization. Key performance indicators include fouling resistance, deposit thickness, and the impact on heat transfer or flow resistance.