Application of mass transfer to rotating biological contactors

Abstract

Mass transfer principles are presently not incorporated in design of most biological reactors. In fixed-film processes, concentration gradients associated with mass transfer can significantly affect system performance. The objective of this study was to develop and verify a model for rotating biological contactors that includes all significant mass transfer resistances, while retaining simplicity for practical applications. In addition to model verification with domestic and papermill pilot plant data, the following applications are presented: calculation of active biofilm depth in terms of either substrate or oxygen depletion, determination of the effect of pure oxygen on system performance as a function of waste strength, determination of the effect of media diameter on the scale-up of pilot plant data, and calculation of optimum stage design as a function of influent waste strength.