A model for oxygen consumption in aerobic heterotrophic biodegradation in dual-phase drainage systems

A mathematical model with two kinetics variations was developed for the description of oxygen consumption in aerobic heterotrophic processes in longitudinal aqueous dual-phase systems where biomass is suspended in the liquid and attached on the solid material surface. This pertains to sewers, drains, rivers and certain wastewater treatment reactors. The model parameters were related to the liquid and solid phases, such as suspended biomass concentration X, its maximum growth rate μmax, water volume V, biofilm oxygen up-take rate BUR, and the biofilm covered area WA. The Monod equation-based zero and first order kinetics were applicable depending on organics concentration. Simulation demonstrated the influence of relevant parameters on the oxygen profile. It illustrated that the suspended biomass can play a critically important role, which generally should not be neglected; the relative importance of the two biomass types is system dependent, and can be quantitatively assessed on the basis of the parameters mentioned above. The potential application of the model is discussed.