Browsing by Author "Pickett, Melanie"
Now showing 1 - 3 of 3
- Results Per Page
- Sort Options
Item Evaluation of Long-Term Microbial Regrowth in Slosh Water Tanks from the International Space Station(2023 International Conference on Environmental Systems, 2023-07-16) Roberson, Luke; Fischer, Jason; Saetta, Daniella; Franco, Carolina; Kodadad, Christina; Hummerick, Mary; Spern, Cory; Yeh, Daniel; Pickett, MelanieThe NASA Launch Services Program (LSP) maintained the SPHERES-Slosh experiment aboard the International Space Station (ISS) between 2013 and 2019. The purpose of the Slosh experiment was to examine how liquids move inside fuel tanks in a microgravity environment. These tanks were similar to water storage tanks planned for use aboard future space systems, where large dormant periods between crew-use will provide similar conditions for biological growth or chemical leaching. The water within the SLOSH tanks remained undisturbed for over five years after testing concluded, providing a unique sample for stored water under microgravity conditions without prior protocols for microbial control such as sterilization or addition of biocides. The Slosh storage tanks were returned to Kennedy Space Center (KSC) aboard SpaceX CRS-18 mission in November 2019. Upon return of the tanks, the water within each tank was analyzed to determine how the water chemistry and biology changed during its tenure in microgravity. The data obtained and described within this publication provided a basis and reasoning for planning water storage and purification treatment methods aboard ISS, Gateway, and future space habitats. Results demonstrated that low microbial concentrations were present within the water, as expected since no biocide treatment was employed, yet no extensive biofilm formation was observed after 5 years even in the presence of microbial food sources such as the polycarbonate structure and food color additives. This experimentation demonstrates that future biofilm studies should be performed on this type of experimental setup with proper controls aboard ISS to examine microbial regrowth to improve microbial control within space water systems.Item Optimization of a Photo-Bioreactor (PBR) for Gravity-independent Wastewater Treatment(2020 International Conference on Environmental Systems, 2020-07-31) Pickett, Melanie; Monje, Oscar; Finn, Riley; Yeh, Daniel; Roberson, LukeFuture missions to establish surface habitats require new, robust ECLSS infrastructure. This work proposes a phototrophic bioreactor for water purification and nutrient delivery for plant production. Key factors require optimization for long-term reliability in such reactors. These factors include gas exchange (CO2 delivery and O2 removal), light delivery, mixing, and biomass harvesting. Additional challenges designing bioreactors for reduced gravity environments arise. Where simple diffuser stones work well on Earth, innovative techniques to deliver gas via membranes are employed for space. Additionally, fluid dynamics become much more complicated; reactor contents must be moved via pumps and no headspace can be maintained (in Earth’s gravity, headspaces allow for buffer capacity and volume for biogas collection for easy extraction). This PMBR is designed to deliver carbon dioxide and remove oxygen via tubular membranes. Material selection and optimization of these membranes was required to maintain the required carbon dioxide to sustain photosynthesis on a highly dense, productive culture. Rather than to utilize gas-lift diffusion for internal culture mixing, pump-induced internal recirculation maintains stratified algal cells with minimal settling (in the 1g lab setup). This PMBR employs the use of a UF membrane for solid-liquid separation. This membrane allows for solid-free, permeate effluent and maintains all of the algal culture within the reactor for continued treatment. Operational backwash techniques are employed to minimize irreversible fouling on the membrane surface. It is during these backwash events that the highest density algae biomass is harvested; harvesting at high densities minimizes dewatering requirements for algae end-use applications. Due to the maintained high cellular density within the reactor, high light techniques (>400 µmol/m2-s) are employed to minimize self-shading effects and enhance photosynthetic efficiency. A novel phototrophic membrane bioreactor (PMBR) is designed for gravity-independent, continuous operation to overcome inherent challenges to provide reliable, sustainable wastewater treatment in future space habitats.Item A Prototype Early Planetary Organic Processor Assembly (OPA) Based on Dual-Stage Anaerobic Membrane Bioreactor (AnMBR) for Fecal and Food Waste Treatment and Resource Recovery(50th International Conference on Environmental Systems, 7/12/2021) Bullard, Talon; Smith, Alexandra; Hoque, Benjamin; Bair, Robert; Delgado-Navarro, Manuel; Long, Paul; Uman, Ahmet; Yeh, Daniel; Pickett, Melanie; Roberson, LukeLong-duration, deep-space exploration and habitation missions demand robust and reliable technologies to ensure crew health, safety, and mission success. Local food production will be essential for crew nutrition and morale. However, at $10,000/lb, the payload costs and mass/volume limitations to transport and provide the necessary resources, including fertilizer, for an anticipated 30-month mission become challenging over time. For mission success and sustainability, the environmental control and life support system (ECLSS) of the near future will need to recover resources from all �waste� sources and be near-closed loop. Organic wastes (e.g., fecal and food) offer a renewable source of C, N, P, water and other trace elements to sustain crop production. However, these high-strength wastes are difficult to treat, due to factors such as heterogeneity, complexity, high water content, and presence of pathogens. To date, there is no flight-ready technology capable of treating mixed organic wastes, creating a technology gap for future space missions. To address this need, a prototype Organic Processor Assembly (OPA) was developed through collaboration between the University of South Florida (USF) and NASA�s Kennedy Space Center (KSC). OPA is based on the anaerobic membrane bioreactor (AnMBR), a hybrid technology coupling high-rate anaerobic digestion with membrane filtration. It was designed for an early planetary base (EPB) scenario to aid in closing the resource recovery loop and decreasing resupply dependence. This presentation discusses initial research pertaining to: 1) design challenges in maximizing hydraulic and organic throughput while minimizing mass and volume of the assembly; 2) capabilities for treating simulated high solids waste under steady and non-steady state conditions; and 3) measured performance parameters such as total organic carbon (TOC), chemical oxygen demand (COD), nutrients, solids, turbidity, and biogas production. Future research and development pertaining to further optimization on system safety, reliability, and expanded treatment capabilities will also be presented.