Browsing by Author "Kojima, Jun"

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Supercritical Water Oxidation for Wastewater Recovery – Status on Recent Testing of Ersatz Wastewater and a Conceptual Design for Near-Term Lunar Application
(2024 International Conference on Environmnetal Systems, 2024-07-21) Scott, Sheldon; Hicks, Michael; Hegde, Uday; Kojima, Jun; Gotti, Daniel; Padilla, Rosa E.; Xu, Yuhao
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.
Supercritical Water Oxidation: A Promising Wastewater Treatment Technology
(51st International Conference on Environmental Systems, 7/10/2022) Figueroa, Adrialis; Flynn, Michael; Padilla, Rosa; Gotti, Daniel; Hegde, Uday; Kojima, Jun; Hicks, Michael
Supercritical water oxidation (SCWO) is a water treatment technology that operates above the critical point of water. The main benefits of SCWO are its ability to completely oxidize organic compounds and mineralize/separate inorganic compounds from wastewater. This suggests SCWO technology can conceptually be applied as a single step water treatment system. Additionally, with proper design and operations it is capable of handling liquid waste streams with high solid loading, thus eliminating the need for extensive pretreatment of the waste stream. This paper provides a description of commercial, academic and NASA developed SCWO reactors. A trade study is presented that shows SCWO is competitive with the International Space Station (ISS) state-of-the-art water recovery systems in all categories except power. However, thermal and mechanical energy recovery approaches are discussed that could be used to reduce SCWO energy consumption to a level that is more competitive with the ISS state-of-the art.