The discussers found this subject of interest having earlier explored this same area of nitrification in an attempt to reduce the required aeration residence times for nitrification in a coupled trickling filter/activated sludge system. The work was initiated in a pilot study of the TF/SC process at the Duck Creek site in Garland and continued in pilot studies at the city of Atlanta. Further work was done analyzing the first months of operation of the TF/SC plant at Duck Creek where the IAWPRC activated sludge model was used to analyze the seeding of nitrifiers from the trickling filter to the contact tank. The discussers even gave the process a name: The TF/PAS process (The Trickling Filter/Pushed Activated Sludge Process). Only some of the work has been reported on (Richards, 1984; Parker and Richards, 1986). It is from this background that the discussers raise a series of questions about the authors’ very interesting contribution.