Section headings and selected papers: Preface. Wastewater and Biomass Characterization. Characterization of wastewater for modelling of activated sludge processes, M. Henze. Temperature effects on wastewater characterization and the release of soluble inert organic material, U. Sollfrank et al.Processes. Processes and modelling of nitrification denitrification biological excess phosphorus removal systems - a review, M. C. Wentzel et al.Modelling and Simulation. Estimation of kinetic parameters of heterotrophic biomass under aerobic conditions and characterization of wastewater for activated sludge modelling, J. Kappeler & W. Gujer. Designing experiments to determine the coefficients of activated sludge models by indentification algorithms, L. Larrea et al. Nitrification kinetics in single-sludge biological nutrient removal activated sludge systems, C. W. Randall et al.Filaments and Solid Separation. Towards a comprehensive model of activated sludge bulking and foaming, D. Jenkins. Comparison of biocenoses from continuous and sequencing batch reactors, J. Wanner. Secondary Clarifiers for Activated Sludge. Modelling of the secondary clarifier combined with the Activated Sludge Model No. 1, R. Dupont & M. Henze. Wastewater treatment process theory and practice: the emerging convergence, D. S. Parker et al. Keyword index.