Simulation of Long-Term Performance of an Innovative Membrane-Aerated Biofilm Reactor

Researchers have observed that the biofilm nitrification rate (NR) in membrane-aerated biofilm reactor (MABR) systems did not deteriorate at low winter temperatures. Using the pilot data, the temperature impacts were studied in two different approaches. A close-to-unity temperature coefficient (theta=1.007) and a constant half-velocity constant (KN,BF=5.7 mgN/L) were obtained from the semiempirical kinetic-based approach, indicating that the bulk NH4+-N concentration, rather than temperature, was determining the biofilm NR. The pilot performance was also simulated in GPS-X 7.0 using all typical kinetic values from scientific literatures except the hydrolysis rate constant. A lower hydrolysis rate constant (0.15 day-1) was used to match the data during calibration and it should be considered as a lumped effect of the pilot conditions. While the temperature effects on biological kinetics are well established, they were masked by the dynamic changes in the MABR biofilm. The apparently weak impact of temperature on the biofilm NR distinguishes the MABR technology as a novel solution for nitrification intensification. The two simulation approaches are proved effective as tools for the process design.