Mathematical Exposition of Simultaneous Nitrification and Aerobic Denitrification

Traditional nitrogen removal techniques include sequential nitrification and aerobic denitrification processes. Recent technologies on nitrogen removal have shown that nitrification and denitrification processes can occur simultaneously in one bioreactor. However, models that ascertain the stoichiometric conversion ratios have not been developed for such systems. In this study simultaneous nitrification and aerobic denitrification data was used in models to describe the substrate consumption and product formation, with simplification using Simpson's rule being used to develop a suitable model. The stoichiometric conversion ratio from NH4-N to NO3-N to NO2-N where approximately found to be ranging from 0.035 0.05 mol: 0.677 – 0.35mol: 1 mol, respectively, indicating that the biological stoichiometric ratios of the simultaneous nitrification and aerobic denitrification processes are not equivalent as previously suggested in theoretical chemical stoichiometric ratios associated with traditional nitrification and denitrification. Keywords— Aerobic denitrification, Biological Stoichiometry, Nitrification, Simultaneity.