Browsing by Author "Pickering, Karen D."
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Item Advances in Spacecraft Brine Water Recovery: Development of a Radial Vaned Capillary Drying Tray(44th International Conference on Environmental Systems, 2014-07-13) Callahan, Michael R.; Sargusingh, Miriam J.; Pickering, Karen D.; Weislogel, Mark M.Technology improvements in the recovery of water from brine are critical to establishing closed-loop water recovery systems, enabling long—duration missions, and achieving a sustained human presence in space. A genre of ‘in-place drying’ brine water recovery concepts, collectively referred to herein as Brine Residual In-Containment, are under development. These brine water recovery concepts aim to increase the overall robustness and reliability of the brine recovery process by performing drying inside the container used for final disposal of the solid residual waste. Implementation of in-place drying techniques have been demonstrated for applications where gravity is present and phase separation occurs naturally by buoyancy—induced effects. In this work, a microgravity—compatible analogue of the gravity-driven phase separation process is considered by exploiting capillarity in the form of surface wetting, surface tension, and container geometry. The proposed design consists of a series of planar radial vanes aligned about a central slotted core. Preliminary testing of the fundamental geometry in a reduced gravity environment has shown the device to spontaneously fill and saturate rapidly, thereby creating a free surface from which evaporation and phase separation can occur similar to a terrestrial-like ‘cylindrical pool’ of fluid. Mathematical modeling and analysis of the design suggest predictable rates of filling and stability of fluid containment as a function of relevant system dimensions; e.g., number of vanes, vane length, width, and thickness. A description of the proposed capillary design solution is presented along with preliminary results from testing, modeling, and analysis of the system.Item Development of Low-Toxicity Wastewater Stabilization for Spacecraft Water Recovery Systems(45th International Conference on Environmental Systems, 2015-07-12) Adam, Niklas; Alvarez, Giraldo; Mitchell, Julie L.; Pickering, Karen D.Wastewater stabilization was an essential component of the spacecraft water cycle. The purpose of stabilizing wastewater was twofold. First, stabilization prevents the breakdown of urea into ammonia, a toxic gas at high concentrations. Second, it prevents the growth of microorganisms, thereby mitigating hardware and water quality issues due to biofilm and planktonic growth. Current stabilization techniques involve oxidizers and strong acids (pH=2) such as chromic and sulfuric acid, which are highly toxic and pose a risk to crew health. The purpose of this effort was to explore less-toxic stabilization techniques, such as food-grade and commercial care preservatives. Additionally, certain preservatives were tested in the presence of a low-toxicity organic acid. Triplicate 300- mL volumes of urine were dosed with a predetermined quantity of stabilizer and stored for 2 weeks. During that time, pH, total organic carbon, ammonia, and turbidity were monitored. Preservatives that showed the lowest visible microbial growth and stable pH were further tested in a 6-month stability study. The results of the 6-month study are also included in this paper.Item Rapid Start-up and Loading of an Attached Growth, Simultaneous Nitrification/Denitrification Membrane Aerated Bioreactor(45th International Conference on Environmental Systems, 2015-07-12) Meyer, Caitlin E.; Pensinger, Stuart; Pickering, Karen D.; Barta, Daniel; Shull, Sarah A.; Vega, Leticia M.; Christenson, Dylan; Jackson, W. AndrewMembrane aerated bioreactors (MABR) are attached-growth biological systems used for simultaneous nitrification and denitrification to reclaim water from waste. This design is an innovative approach to common terrestrial wastewater treatments for nitrogen and carbon removal and implementing a biologically-based water treatment system for long- duration human exploration is an attractive, low energy alternative to physiochemical processes. Two obstacles to implementing such a system are (1) the “start-up” duration from inoculation to steady-state operations and (2) the amount of surface area needed for the biological activity to occur. The Advanced Water Recovery Systems (AWRS) team at JSC explored these two issues through two tests; a rapid inoculation study and a wastewater loading study. Results from these tests demonstrate that the duration from inoculation to steady state can be reduced to under two weeks, and that despite low ammonium removal rates, the MABRs are oversized.