Organic Carbon and Nitrogen Removal in a Single-Stage Nitrification-Denitrification/Anammox (NDX) System Treating Early Planetary Base (EPB) Wastewater

Using biological processes to reuse wastewater for potable applications is an alternative approach to minimize payload costs in space. Reducing nitrogen and carbon levels, the two main pollutants of waste streams, is a challenging requirement in the water recycling process. Well established conventional nitrification-denitrification processes cannot lead to high organic nitrogen removal where there is insufficient organic carbon (a substrate of denitrifying bacteria). The Anammox process is a promising technology to anaerobically convert ammonia to nitrogen gas without the need for organic matter. The main goal of this study was to test a sing-stage nitrification-denitrification/anammox (NDX) biological system to remove organic carbon and nitrogen from an Early Planetary Base (EPB) space wastewater, using minimal energy and consumables. The NDX system consists of a total volume of 72 L with a 42 liters treatment zone including a set of three foam media scaffolds that provide surface area for bacterial growth and a sufficient O2 barrier to ensure a reliable anoxic zone in the foam interior. The system was continuously operated for 11 months over a range of C and N loading rates (1200 (g/day), and 1400 (g-N/day), respectively). The system has achieved organic C removal in excess of 1100 (g/day), and N removal rates up to 1000(g-N/day).