A Sensitivity Analysis of Model Parameters Influencing the Biofilm Nitrification Rate: Comparison between the Aerated Biofilm Reactor (MABR) and Integrated Fixed Film Activated Sludge (IFAS) Process

The Membrane Aerated Biofilm Reactor (MABR) achieves energy-efficient aeration, total nitrogen removal, and increased treatment capacity. Commercial interest in MABRs has grown significantly given the launch of MABR products by three different technology providers in the past three years. An important tool for the design and implementation of full-scale MABR installations is process modeling. However, the mass transport scheme of the MABR differs from conventional biofilm systems, such as an integrated fixed film activated sludge (IFAS) process. A sensitivity analysis was conducted on the biofilm nitrification rate, a key biofilm system design parameter, for MABR and IFAS process models developed in GPS-X. The models differed in their most sensitive parameters. For the IFAS model, liquid diffusion layer thickness was most influential on the biofilm nitrification rate, while for the MABR, the reduction of ammonia diffusion in the biofilm when compared to water and biofilm thickness were the most significant. These results have implications for modeling and calibration of MABR biofilms. Further, these results inform future pilot work, where key factors influencing performance and stability of the GE ZeeLung™ technology will be evaluated.