Stoichiometry of biological nitrogen transformation in denitrificationbioreactors

Abstract

The mechanisms of biological nitrogen transformations are very important for analysis, design, operation and optimal control of natural ecosystems or engineered systems for nitrogen removal. In general, the nitrogen compounds transformation direction and kinetics depended on bacterial metabolic activity and environmental (aqueous medium) conditions. The stoichiometric equations of ammonification, nitrification and denitrification have demonstrated that the nitrogen cycle in nature is rather complicated. In this study focus on denitrification process, this based on elements mass balance equation. Laboratory scale tests have revealed that during the analyzed period of 235 days in bioreactor with deciduous woodchips the reduction of nitrate-nitrogen mass was reached 51% compared with the total amount observed in the inflow mass. During the same period the reduction of nitrate-nitrogen mass was reached, respectively, in the bioreactor with conifer woodchips - 64%, and with mixed woodchips filler - 63%.