f
Facilitation factor: Parameter equal to the enhancement factor minus one.
Feed pretreatment: Process carried out on a crude feed stream, prior to feeding to a membrane separation system, to eliminate objectionable components such as biological agents and colloids that might impede the stable operation of the membrane.
Fixed ions: Immobile ions bound by covalent bonds with polymer chains of ion-exchange or other membrane (see Anchored (bound or fixed) carrier)
Flux: Ji, [kmol m2 s-1]: Number of moles, volume, or mass of a specified component i passing per unit time through a unit of membrane surface area normal to the thickness direction. {Note: other commonly used units for Ji include [m3/m-2 s-1], or [kg/m-2s-1] or [m3 (measured at standard temperature and pressure) m-2 s-1]}.
Forcing channel: A space in an apparatus that is limited by two (identical0 membranes; from this space the separated stream is directed under pressure through the membrane.
Forward osmosis: Process of osmotic pressure for obtaining energy, controlled dilution of solutions etc.
Fouling: Process resulting in loss of performance of a membrane due to the deposition of suspended or dissolved substances on its external surfaces, at its pore openings, or within its pores.
