Hybrid Life Support System Full Scale Testing: Integrated Bioreactor-Desalination Long Term Testing

As space habitats are developed in reduced gravity environments, life support systems will be able to evolve to harness the gravity present enabling a wider diversity of treatment systems that can be more robust and reduce consumable mass. Hybrid life support systems that combine biological regenerative processors with physio-chemical systems are one system that could provide such benefits. In this effort, gravity-dependent bioreactors were tested for extended periods for their capacity to treat space-based greywater and urine + flush water (U+F), separately. Effluent from the greywater biological reactor was further processed using a small-scale low-pressure reverse osmosis (RO) unit. Effluent from the urine biological reactor was desalinated using a static distillation system. Our objectives were to demonstrate if 1) the bioreactor could be used as the RO recycle tank, reducing the system mass and volume; and 2), if operating the urine bioreactor to produce NO3- instead of NO2- as the oxidized NH3 product would improve distillate quality. Using the greywater biological reactor as the RO system recycle tank reduced the life of the prefilter and RO membrane but had no effect on water quality. Operating the urine bioreactor to produce NO3- did reduce NOx- carryover to the distillate. Our results support the ability to use biological pretreatment in concert with desalination systems to eliminate the need for storage tanks, brine processing, reduce system mass and complexity, consumable mass, and provide robust systems.