This book has been a long time in preparation. Initially it grew out of
our frustrating attempts over the past ten years to identify the
filamentous bacteria seen in large numbers in most activated sludge
plants, and the realization that we know very little about them and the
other microbial populations in these systems. Unfortunately this book
does not provide many answers to the problems these filamentous bacteria
can cause, but we hope it might encourage microbiologists and engineers
to communi- cate more with each other and to spend some time trying to
understand the tax- onomy, ecology and physiology of activated sludge
microbes. It is now very timely, for example, to try to provide these
filamentous bacteria with proper taxonomically valid names and to
determine their correct place in bacterial classifications. This book is
not meant to compete directly with the books by Gray (1989, 1990) nor
the excellent manual published by Jenkins and coworkers (1993b), which
has been invaluable to us and others trying to identify filamentous
bacteria. Wanner's book (1994a) also provides an excellent account of
the problems of bulking and foaming caused by filamentous bacteria.
These publications and others by Eikelboom's group have made an enormous
contribution to the study of filamentous bacteria, and will con- tinue
to do so.