PARAMETER DETERMINATION FOR THE INTERMITTENTLY AERATED COMPLETELY MIXED (IACM) PROCESS

A methodology has been developed to estimate some process parameters for an intermittently aerated completely mixed (IACM) system used for carbon oxidation, nitrification and denitrification. The approach is able to distinguish between heterotrophic and autotrophic microorganisms, and can account for the variation of kinetic parameters under aerobic and anoxic conditions. The method of least squares was employed to solve a set of equations to obtain yield and decay rates for heterotrophs, whereas a trial-and-error approach was used for autotrophs. A weighting matrix was incorporated into the equations to consider the variation in the number of experimental data points. Parameters determined in this paper include heterotrophic biomass yield and decay rates for aerobic and anoxic periods, autotrophic biomass yield and decay rate, nitrification rate, denitrification rate, cell nitrogen to carbon consumption ratio, and fraction of autotrophic biomass. The aeration fraction affects the effective aerobic and anoxic hydraulic retention times of the IACM process, which in turn affect the other parameters.