Part 1 Large-scale biological aerated filtration: parameters affecting nitrifying biofilm reactors, M. Boller et al. Part 2 Tertiary nitrification: dynamics of a nitrifying bacteria population in a biofilm controlled by an oxygen microelectrode, H. Horn. Part 3 Denitrification: carbon utilization in denitrifying biofilters, J. la Cour Jansen et al. Part 4 Nitrogen and phosphorus removal: combined nitrogen and phosphorus removal in a full-scale continuous up-flow sand filter, B. Hultman et al. Part 5 Upgrading with biofilms: pre- or post-denitrification at biological filter works? a case study, A. Dee et al. Part 6 Full-scale case studies: paper mill effluent treatment using biofiltration, J.M. Rovel et al. Part 7 Modelling population dynamics: competition in biofilms, T.C. Zhang et al. Part 8 Anaerobic treatment and biofilm structure: fractal properties of the RBC biofilm structure, W.M. Zahid and J.J. Ganczarczyk. Part 9 Fluidized beds: advances in biofilm aerobic reactors ensuring effective biofilm activity control, V. Lazarova and J. Manem. Part 10 Modelling of multiphase fluidized beds: kinetic study and mathematical modelling of biofilm in an anaerobic fluidized bed, T. Imai et al. Part 11 Special denitrification: nitrogen removal characteristics of nitrification and denitrification filters, F. Cecen and I.E. Gonenc. Part 12 Mixed biofilm modelling: nitrogen removal from wastewaters by a bio-reactor with partially and fully submerged rotating biofilms, Y. Watanabe et al. Part 13 Diffusion: the calculation of simultaneous effective diffusion coefficients of the substrates in a fluidized bed biofilm reactor, H. Beyenal and A. Tanyolac. Part 14 Denitrification in potable waters: fluidized bed reactor operation for groundwater denitrification, M. Green et al. Part 15 Special substances: aerobic biodegradation of azo dyes in biofilms, H. Jiang and P.L. Bishop.