Model based study of the first stage of biological nitrification <f>(NH4+</f> oxidation to <f>NO2−)</f>

Reaction mechanisms are generated for the first stage of biological nitrification (<f>NH4+⇒NO2−</f>) by using graph theoretical methods and the chemical information for reaction intermediates. On this basis, a large number of kinetic models are obtained. As a result of model discrimination, a kinetic model is derived to describe the kinetics of the biological nitrification reaction appropriately. The kinetic constants of the model were estimated by implementation of a differential method for parameter estimation. The selection of a correct reaction mechanism and kinetic model is performed on the basis of the experimental data obtained using laboratory scale equipment. A kinetic model which appropriately describes the kinetics of ammonia oxidation into nitrite and its parameter estimates is obtained. It is in correspondence with the mechanism including the reaction step of formation and decomposition of an intermediate complex between ammonia, bacteria and oxygen. [Copyright &y& Elsevier]