Comparative performance of biofilm reactor types

Development of a unified model of biofilm‐reactor kinetics is based on substrate‐utilization kinetics, mass transport, biofilm growth, and reactor analysis. The model is applied to steady‐state conditions for complete‐mix, fixed‐bed, and fluidized‐bed reactors with and without recycle. The results of modeling experiments demonstrate that simple loading factors and kinetic relationships are insufficient to describe the performance of a variety of biofilm processes. Instead, the interactions among utilization kinetics, biofilm growth, and reactor configuration determine the performance. For example, fluidized‐bed reactors can achieve superior performance to complete‐mix and fixed‐bed reactors because the biofilm is evenly distributed throughout the reactor while the liquid regime has plug‐flow characteristics. When it is possible, experimental results which demonstrate key concepts are presented.