Effects of influent substrate concentration on the kinetics of natural microbial populations in continuous culture

In order to determine whether the influent substrate concentration exerts an effect upon the kinetics of soluble substrate removal by natural microbial populations growing in continuous culture experiments were run using a multicomponent substrate. A two-level factorial experimental design was employed with reactor dilution rate and influent substrate concentration as the independent variables. Analysis of the results indicated that both variables exerted a significant effect (1% level) upon the effluent soluble COD. It was possible to model the system using the linear approximation of the Monod equation resulting in an equation of the general form: S=K′S₀D + K″S₀The findings of the study indicate that engineers responsible for the design and operation of wastewater treatment facilities should consider the influent substrate concentration when choosing a mean cell residence time for the system.