Preface. 1. Introduction to the microorganisms found in activated sludge processes; R.J. Seviour, L.L. Blackall. 2. The activated sludge process; R.J. Seviour, et al. 3. The normal microbial communities of activated sludge plants; R.J. Seviour. 4. Factors affecting the occurrence of filamentous bacteria in activated sludge plants; R.J. Seviour. 5. Current taxonomic status of filamentous bacteria found in activated sludge plants; R.J. Seviour, L.L. Blackall. 6. Bulking; L.L. Blackall. 7. Foaming; J. Soddell. 8. The microbiology of nitrogen removal in activated sludge systems; L.L. Blackall, P. Burrell. 9. Microbiological aspects of phosphorus removal in activated sludge systems; P.I. Bond, G.N. Rees. 10. Practical methods for the examination and characterization of activated sludge; K.C. Lindrea, et al. 11. Descriptions of the filamentous bacteria causing bulking and foaming in activated sludge plants; E.M. Seviour, et al. Flossary, References. Index.