MICROSCOPIC AND ENZYMATIC INVESTIGATIONS ON BIOFILMS OF WASTE-WATER TREATMENT SYSTEMS

In biological wastewater treatment inorganic and organic substances ar e fixed and metabolized by mixed populations of microorganisms forming either activated sludge flocs or biofilms. Not only the type of waste water but also the operational conditions promote the development of a n adapted biocenosis of microorganisms with specialized enzymatic func tions. Understanding the biological properties of the microorganisms, it is possible to assess the prevailing conditions in their natural en vironment. Regular microscopic and enzymatic investigations of activat ed sludge and biofilms thus improve the assessment of the stability of the processes and support troubleshooting in wastewater treatment pla nts. While the role of bacteria is often discussed, the importance of ciliated protozoes and metazoes for the maintenance of the stability o f biofilm systems is rarely mentioned. in this paper we intend to show some new results of direct microscopic observations in different sort s of biofilm systems focussing upon ciliated protozoes and metazoes. P ractical results will demonstrate the relation between enzymatic analy sis, microscopic investigations and performance of biofilm systems. (C ) 1997 IAWQ. Published by Elsevier Science Ltd.