Design and Analysis of Mixing for an Aeration Tank

The kinetics of substrate removal for the activated sludge process were examined for the axial dispersed plug flow model. By use of a laboratory aeration tank various other models were studied to determine their applicability. Several methods of fitting the experimental response curves to the theoretical curves were examined and a simplified technique presented for the dispersion model. This technique was used to study the effects of temperature, detention time, and air-flow on mixing. A full-scale prototype tank was compared to the laboratory results and a relationship developed between their axial dispersion coefficients. The possible occurrence of short-circuiting through the stagnant-core was studied. The use of the various equations and figures for design is presented in a worked example.