ALS Greywater Treatment: Effects of Bicarbonate on Nitrification

In this paper we explore the stoichiometry and kinetics of nitrification reactions (ammonia oxidation to nitrite and nitrite oxidation to nitrate) and the use of fixed film and/or suspended growth bioreactors for treatment of wastewater in Advanced Life Support Systems. While the main focus of the paper is on the development of a model for predicting the theoretical performance of nitrifying reactors, in particular, the JSC designed slug-flow nitrifying bioreactor, it also provides a broader view of the potential benefits of using controlled bioreactors. This broader view is based on two assumptions. First that bioreactors are robust systems that respond in predictable, and generally positive, ways to alterations in system loads. Second, that bioreactors can be made more robust and controllable than the physical-chemical reactors commonly selected for use in space flight. To realize this goal bioreactor responsiveness can and should be quantified through the use of carefully designed models and experiments to yield expert system control vehicles.