INTRICACIES OF MODELING THE EMERGING INTEGRATED FIXED-FILM ACTIVATED SLUDGE (IFAS) PROCESS

摘要

The Integrated Fixed-film Activated Sludge (IFAS) process is a technology that provides the means for effective nitrogen removal in a smaller footprint than those for conventional biological nitrification processes. It is particularly attractive for retrofitting carbonaceous-only activated sludge treatment plants as, in many cases, it can be added without the need for expanding reactor or clarifier volume. Improvements to the design of IFAS plants have been developed using process models based on the GPS-X Hybrid model, which was originally conceived for the Kaldnes Moving Bed Biofilm Reactor (MBBR), but contains all the features needed to model IFAS. The model was calibrated using pilot plant data. This paper presents the calibration steps along with typical operating data for the pilot plant. The paper also includes a discussion of the most pertinent calibration parameters, in particular the anoxic oxygen half-saturation coefficient and the hydrolysis rates used to calibrate nitrate concentrations. Nitrate concentrations measured in the pilot plant are much lower than would be predicted using a conventional activated sludge model, because of the high level of simultaneous nitrification and denitrification (SND) observed.