Biofilm characterization and activity analysis in water and wastewater treatment

Biofilm composition and activity are two important parameters for the successful operation and control of fixed film processes in water and wastewater treatment. Widely used parameters for biofilm characterization are biofilm thickness, total dry weight and total cell count. These parameters are, however, not sufficient to describe biofilm activity. Improved analytical methods and procedures are needed in order to understand the physiological behaviour of the fixed biomass. Common methods used to analyse biofilms are critically reviewed in terms of their principle, complexity, reproducibility, sensitivity and cost. Conventional and advanced analytical methods are classified in three main categories: (1) biofilm formation and structure; (2) biofilm composition described in terms of total biofilm amount, specific biofilm components and cellular components; and (3) biomass activity descriptors. The discussion focused on the potential of these methods for accurate biofilm characterization and biomass activity estimation in fundamental research and for the practical needs of wastewater treatment operation and control.