Distribution of oxygen consumption in an aeration tank:
comparison of engineering approaches and computerized simulation

Summary

A review of engineering and numerical approaches to describing the distribution of oxygen consumption in the aerobic zone of an aeration tank, a key element of biological wastewater treatment systems is presented. The schemes indicated in the engineering literature (EPA Design Manual, S. Jeyanagam, R. Venner, J. Tchobanoglos, D. Rosso, D. A. Danilovich, and A. N. Epov) are considered. The listed approaches are compared with the results of the computerized simulation performed in the GPS-X software environment using the ASM3 model and the series-connected reactor model. The simulation was carried out for different temperature conditions reflecting seasonal variation. It is shown that the oxygen distribution schemes adopted in engineering practice do not take into account the effect of temperature, flow velocity and longitudinal dispersion, what can lead to significant deviations in the design of aeration tanks. A unified approach to comparing oxygen distribution processes is proposed. Practical recommendations for the use of computerized simulation to specify design solutions are presented.

Key words

biological treatment , aeration tank , GPS-X , series-connected reactor model , ASM3 , temperature conditions , oxygen consumption

Calculation of the longitudinal dispersion coefficient and number of cells in the model of series-connected reactors Part
1. Review and engineering analysis of methods

Summary

A review and comparative analysis of engineering methods for calculating the longitudinal dispersion coefficient and the equivalent number of cells in a model of series-connected reactors used to describe hydrodynamics in aeration tanks are presented. Both empirical and semi-empirical formulas (B. Chambers and G. L. Jones, K. L. Murphy and B. I. Boyko, P. Harremoes, K. Fujie, and others) and dimensional and substantiated models (B. M. Khudenko and E. A. Shpirt, O. Potier, and Y. Le Moullec) are considered. The classification of methods by the type of data used in calculations and by the degree of sensitivity to geometric and aerodynamic parameters is given. The criteria for the applicability of approaches at different stages of design, simulation and upgrade of the wastewater treatment facilities are formulated. The paper represents the first part of two articles and considers the calculation and interpretation of the number of cells in bioreactors. The second part will be on the practical application of methods by the example of aeration tanks of various configurations.

Key words

wastewater , bioreactor , hydrodynamics , longitudinal dispersion coefficient , series-connected reactor model , cell number