Evaluation of Anoxic Heterotrophic Yield Using Multiple Calculation Methods

The stoichiometric parameter namely "Yield Coefficient" associated with growth of certain organism can be determined by direct measurement and/or calculated indirectly. The focus of this paper was on the anoxic yield of heterotrophic organisms using ethanol as an external carbon source during the denitrification process. In the literature, it was observed that yield coefficients can vary for the same substrate, which can be referred to the relative acclimation to the substrate. The aim of this study was to evaluate the yields determined through various catabolic and anabolic estimations. This paper presents ten different yield coefficient calculation methods under anoxic conditions in a sequencing batch reactor using ethanol as an external substrate. The range of anoxic yield using different calculation methods was between 0.423 +/- 0.014 to 0.512 +/- 0.021 mgCOD/mgCOD at 20 degrees C. It was concluded that there was no statistically significant difference between the yield values calculated from the different methods. Depending of what parameters can be measured correctly for a particular experiment or setup, a particular method can be selected using those parameters to calculate the yield.