The objective was to evaluate the response of the biological activity at the carbon solid-liquid interface of an expanded bed adsorber. The evaluation of the biological activity was performed by conducting non-flow kinetic studies, continuous flow kinetic studies, and oxygen uptake studies. The research was divided into two phases. Phase I consisted of the non-flow kinetics whereas Phase II consisted of the continuous flow kinetics and the oxygen uptake studies. The results indicate that the response of the biological film supported by granular carbon can be defined by conducting oxygen uptake studies. Biological activity of the attached film was established through the use of an energy-total energy constant. This constant can be used to predict oxygen demand for the attached film on granular carbon used in expanded bed adsorbers. (Modified author abstract)