Long-duration human spaceflight comes with grand engineering challenges. Cabin pressure is predominantly dictated by the amount of inert nitrogen gas (N2) and small losses may create conditions not fit for life. Especially for long term deep-Space missions, in-situ regeneration of N2 is key. The Nitrogenisor project aims to recover nitrogen gas from urine by ammonification and partial nitritation/anammox, using microgravity compatible aeration and degassing technology.