Use of Nonsteady-state Biofilm Model to characterize heterotrophic and autotrophic biomass within aerobic granules

Abstract

A pseudo-analytical solution for a Nonsteady-state Biofilm Model (NSBM) was used to describe heterotrophic and autotrophic biofilms within aerobic granules. This model was validated with the experimental results obtained from a granule-based SBR process that removes organics and ammonia simultaneously. The calibrated model (with boundary conditions including involved species, operating conditions, granular characteristics and biological reactions) predicted effluent COD and NH4 values that were in good agreement with the measured values. The model simulation showed that the increase of the substrate concentration did not dramatically influence the flux trends if the biomass concentration in the reactor is insufficient (less than 1000 mg VSS/L). The heterotrophic and autotrophic biofilms develop layer by layer on the outside of the aerobic granules. These can form simultaneously in independent patterns for substrate utilization and biomass growth. The NSBM could be an effective prediction method for the understanding of aerobic granulation.