Water is a necessary resource for crewed space exploration missions and the efficient reclamation of aqueous waste streams presents the only long-term viable option for achieving a sustainable extra-terrestrial human presence. Although early Artemis missions are considering water as part of the payload manifest, it would be extremely advantageous if follow-on missions were supplied — either in total or in part — by a reclamation technology that would operate autonomously between missions. NASA Glenn Research Center (GRC) employs a Supercritical Water Oxidation (SCWO) process that has demonstrated the successful destruction of all organic hydrocarbons in a typical International Space Station (ISS) aqueous waste stream. SCWO conversion has shown reductions in Total Organic Carbon (TOC) consistently greater than 99% with reactor residence times less than 3 s and average reaction temperatures ca. 620° C. Recent effort has been directed toward developing a conceptual design based on the current tubular reactor used in the evaluation of the conversion of SCWO. This conceptual design along with the results of recent SCWO conversion experiments will be presented. Recent design enhancements to achieve shorter residence times along with "production simulation" tests will be presented. The diagnostics used in assessing the extent of the waste conversion include a total organic carbon (TOC) analysis, Raman analysis, along with measurements of pH, turbidity, and conductivity. Results obtained from the modified reactor configuration will also be compared to those of the Phase I configuration presented in earlier work.
Scott et al. (2024) studied this question.