Determination of biofilm thickness on a supported biofilm reactor membrane

A method for evaluating the thickness of biofilm in a reactor biofilm supported membrane (MSBR) of the type comprising an internal passage containing a gaseous phase, a liquid phase and a membrane permeable to gases that provides an interface between the gas phase and the liquid, the method comprising the steps of: - loading the internal passage in an inert gas. - closing the internal passage to establish an initial elevated pressure in the internal passage; - measuring the speed of pressure change within the lumen; and - correlating the rate of change of pressure (dP / dt) with the thickness of the biofilm.