Biofilm activity control is an important requirement for the successful operation of biofilm reactors for wastewater treatment. Widely used parameters for biofilm characterisation are the biofilm thickness and total dry weight. These characteristics are, however, not sufficient to describe biofilm activity. Understanding of the physiological behaviour of the fixed biomass needs improved analytical methods and procedures. Direct application of known methods for free biomass characterisation to biofilm analysis is not always possible and is not well studied and developed.

In this paper an integrated approach is proposed for representative estimation of biofilm activity, by means of appropriate analytical methods to control biofilm dynamics and wastewater treatment process performance. The relevance of this approach is tested using different nitrifying biofilms.