Definition of Term

foaminess

(English) This term relates to the persistence of foams and is widely used but not well defined. At least three processes take place during the whole life of a typical liquid foam: (1) foam rearrangement - the numbers, positions and linear dimensions of the bubbles change in time; (2) liquids present in the foam lamellae exhibit a continuous downflow movement because of gravitation; (3) lamellae burst - usually, there is a fourth process which influences the other three - evaporation. However, if foaming takes place in largely closed ecosystems, this process is negligible. The persistence of a foam is determined by the frequency of collapse of the lamellae. When all lamellae have collapsed, that is, all bubbles have burst, no foam remains. Measurements of foaminess or foam persistence are not consistent and depend on the method employed. Unfortunately, no standards exist to date which would be as consistent as are definitions for surface tension, viscosity, and analogous physical quantities. Foams do occur in intensive aquaculture systems in various forms and foaming separation is often used in water treatment procedures. In aquaculture systems, foaminess (foam collapse time) is frequently interpreted as the time required to completely allow the disintegration of foam bubbles under undisturbed conditions (i.e., stagnant water).

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