A simple mass balance model of nitrogen flow in a bioregenerative life support system

A mathematical model of the nitrogen cycle in a bioregenerative life support system (BLSS) was developed to help conceptualize and quantify nitrogen flux and storage in BLSS processes and subsystems. The mathematical model was initially designed as a simple mass balance, donor-controlled system that quantified the amount of nitrogen in moles per person. Dynamic equations were then applied to describe certain relationships more accurately. Comparison of nitrogen fluxes suggests that even at very low atmospheric leakage rates, loss of nitrogen gas would account for the largest nitrogen movement in the "closed" system. This observation decreases the relative importance of denitrification and nitrification in closed system nitrogen balances. Sensitivity analysis was used to determine the relative stability of various model subsystems, and demonstrated the importance of plant nitrogen uptake on overall system dynamics of nitrogen.