Use of microautoradiography and fluorescent in situ hybridization for characterization of microbial activity in activated sludge

In order to understand the function of the different microorganisms in acti vated sludge, it is important to know their identity, diversity and activit y. In this paper we describe how microautoradiography (MAR) and fluorescent in situ hybridization (FISH) can be used to characterize and enumerate fun ctionally important groups of microorganisms in activated sludge. The princ iples for the methods, some important methodological aspects and limitation s of the procedures and some important results are discussed. Special focus is on the examination of the in situ physiology of certain filamentous mic roorganisms and a discussion about the use of such information in mathemati cal models of the activated sludge processes. (C) 1999 IAWQ Published by El sevier Science Ltd. All rights reserved.