Browsing by Author "Koss, Lawrence"

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An Automated Test Bed for Rapid Characterization of Sorbent Materials for Siloxane Removal in Contaminated Airstreams
(45th International Conference on Environmental Systems, 2015-07-12) Richards, Jeffrey; Koss, Lawrence; Monje, Oscar
Polydimethylsiloxanes (PDMS) degrade into dimethylsilanediol (DMSD), a soluble compound that affects the performance of several life support systems on the International Space Station (ISS). In industry, PDMS are typically removed using gas purification equipment using commercial sorbents. A bench scale test bed was developed at KSC for evaluating candidate commercial sorbents for the removal of gas phase PDMS using environmental conditions found on ISS (i.e., RH 40% and 23 oC). The test bed consists of four subsystems: 1) a Kin-Tek gas generator to supply a humid gas stream with the desired concentration of siloxanes and volatile organic compounds (VOCs); 2) a sorbent assay tube containing sorbent materials during testing; 3) an environmental monitoring and control system consisting of valves, a heater, and temperature, humidity, and pressure sensors; and 4) an automated gas analysis system to measure pre- and post-sorbent siloxane concentrations using a gas chromatograph and Valco sampling valves. The adsorptive capacity of Chemsorb® 1000, an activated carbon sorbent derived from coconut shell char, for PDMS was tested in this system. The sorbent was challenged with a linear (L2, Hexamethyldisiloxane) and a cyclic (D3, Hexamethylcyclotrisiloxane) siloxane under ISS nominal conditions and adsorptive capacities were determined from breakthrough curves.
Design and operation of Photomembrane Bioreactor (PMBR) to balance nitrogen in high-ammonia wastewater treatment effluents
(51st International Conference on Environmental Systems, 7/10/2022) Saetta, Daniella; Fischer, Jason; Finn, Joshua; Bullard, Talon; Smith, Alexandra; Koss, Lawrence; Yeh, Daniel; Monje, Oscar; Roberson, Luke
A flat-plate photomembrane bioreactor (PMBR) has been designed and used as one component of a bioregenerative water system at NASA's Kennedy Space Center (KSC). PMBRs are systems that use a microalgae--bacteria consortium to treat high-nutrient water streams. The main goal of the PMBR at KSC is to balance the nitrogen cycle in the effluent of upstream anaerobic membrane bioreactor (AnMBR). The membrane component of the PMBR allows for biomass accumulation within the reactor to increase nutrient removal rates while producing a filtered permeate for downstream use. The upstream AnMBR releases bound nutrients in wastewater as it digests organic carbon without the presence of oxygen. The effluent is low in carbon and high in total nitrogen, mainly found in the ammonia-nitrogen form. The novelty of this system lies on its ability to nitrify ammonia to nitrate, creating a more suitable nitrogen fertilizer for downstream plant growth systems. This conference paper will present the PMBR design parameters, operation parameters, and lessons learned during its first 100 days. The PMBR has been able to convert a significant percentage of ammonia to nitrate, making it a suitable technology to create a sustainable nutrient source for plant growth systems. As the algal biomass grew via photosynthesis, carbon dioxide at concentrations equivalent to those found on the International Space Station (approximately 3000 ppm) was used to produce the oxygen needed for bacteria to nitrify the ammonia in the AnMBR effluent. Overall, this conference paper will detail how the PMBR technology designed in this project filled the gap between the AnMBR and downstream plant systems for lunar and planetary missions.
Development of a photosynthesis measurement chamber under different airspeeds for applications in future space crop-production facilities
(2020 International Conference on Environmental Systems, 2020-07-31) Poulet, Lucie; Gildersleeve, Michael; Koss, Lawrence; Massa, Gioia D.; Wheeler, Raymond M.
Space crop production systems are being developed to grow fresh produce in-situ to supplement the astronauts’ diet, but the required ventilation rates for crops in different gravity environments remains poorly understood. The reduction or lack of buoyancy-driven convection in reduced gravity environments leads to impaired gas exchange (CO2 absorption, water transpiration and O2 release) at the leaf surface if no extra ventilation is provided, and this could lead to a reduction in biomass production in the long run. To better characterize the influence of different airspeeds on photosynthesis and be able to model this in low gravity, a chamber was designed to interface with a LI-6800 portable photosynthesis system. This paper details the design of this chamber, specifically made to measure whole-plant and small canopy gas exchange at different airspeeds. The fans provide turbulent mixing in the chamber to ensure that it behaves like a continuous stirred tank reactor (CSTR) and that the residence time distribution (RTD) is the same for any fan speed; the computational fluid dynamic (CFD) model of the gas domain (the air in the chamber) hence uses a k-omega turbulence model. An airflow map of the chamber was created using anemometer measurements for the different airspeeds tested, and this was used together with the CFD simulation results to relate the experimentally measured fan outputs to actual airspeeds on top of an artificial plant. The chamber is equipped with thermocouples that track leaf surface temperature, which relate to the LI-6800 gas exchange measurements via a plant energy balance. Environmental parameters (air temperature, relative humidity, CO2 level) are controlled by the LI-6800. This work was funded by NASA Space Biology through the NASA postdoctoral program / USRA.
Microbial Characterization of Heat Melt Compaction for Treatment of Space Generated Solid Wastes
(51st International Conference on Environmental Systems, 7/10/2022) Hummerick, Mary; Fisher, Jason; Wheeler, Raymond; Richardson, Tra-My Justine; Ewert, Michael; Lee, Jeffrey; Koss, Lawrence
One treatment process in development for solid waste management in space has been the Trash Compaction Processing System (TCPS). Heat Melt Compaction (HMC) technology, a TCPS liked hardware, which is operated to reduce trash volume and safen the trash by compaction and heat, while simultaneously removing water. Human space mission wastes typically contain large percentages contaminated wet solid waste. The HMC is being developed to be a multi-function means of water recovery, volume reduction, and the safening of contaminant-rich trash with the potential for waste stabilization and/or sterilization. To determine the efficacy of the HMC treatment to kill microorganisms in solid waste and remain biologically stable, testing was done on three tiles produced by HMC Gen 2 at Ames Research Center. Samples were shipped to Kennedy Space Center to test for microbial viability after compaction, determine the bio-stability of the HMC disks during storage (43 days), and assess potential airborne contaminate microbial growth on surfaces. In addition to the products of waste processing, there is a concern that the crew might come into contact with hardware surfaces that have been contaminated by microorganisms during waste processing. The extent of microbial surface contamination of waste processing hardware was determined by surface sample swabbing and analysis for total bacterial and yeast counts and cultivable counts of aerobic and anaerobic bacteria, spore-forming bacteria, and fungi. Results indicate that trash processing increased bacterial counts on the surfaces of the compacter. All but one biological indicator spore strip imbedded in the tiles were negative for growth after incubation for five days indicating effective sterilization through the heat melt compaction process. Analysis of core samples and surface growth of tiles inoculated with Aspergillus niger fungal spores incubated at three different humidities indicate that HMC created tiles do not support the proliferation of bacterial and fungal growth.
Sodium Chloride Removal from International Space Station Wastewater Brine to Generate Plant Fertilizer
(50th International Conference on Environmental Systems, 7/12/2021) Irwin, Tesia; Diaz, Angie; Li, Wenyan; Lunn, Griffin M.; Koss, Lawrence; Wheeler, Raymond; Callahan, Michael; Jackson, Andrew; Calle, Luz M.
Water is a critical resource for human exploration beyond low earth orbit. There are two general mechanisms for wastewater recovery. The current practice on the International Space Station (ISS) is vapor compression distillation, which requires a significant amount of consumables and has a water recovery rate of around 75%. An alternative approach is a biological water processor (BWP), integrated with a forward osmosis secondary treatment system (FOST). The integrated system is expected to recover 95% of the initial wastewater volume. The remaining 5% is lost as a concentrated brine. For a closed-loop water recovery system, all nutrients should be recovered and reused. For far-term life support, plant systems will be introduced to grow in situ foods, as well as to regenerate O2 and remove CO2 from cabin air. To do so will require a continuous flow of nutrients or fertilizer. The wastewater brine provides a rich source of nutrients for plants, but its high sodium content presents a challenge for most food crops. Direct recycling of urine to crops for life support was tested in Bios-3 (Russia) and resulted in salinization of growth systems. Halophytic plants have been tested with high Na inputs but their yields are low. A thermal swing process has been proposed to separate NaCl from other salts in wastewater for use as plant fertilizer. The paper reports the initial proof of concept testing results, which showed that the thermal swing process is a promising approach for NaCl reduction from wastewater, as well as the tasks planned for further development.
Unleashing the Power of Anaerobic–phototrophic Membrane Bioreactors for Sustainable Bioregenerative Life Support
(2024 International Conference on Environmnetal Systems, 2024-07-21) Fischer, Jason; Koss, Lawrence; Saetta, Daniella; Bullard, Talon; Smith, Alexandra; Yeh, Daniel; Roberson, Luke
Using the core ideals of bioregenerative life support, an anaerobic–phototrophic membrane bioreactor (APMBR) has been designed and operated at NASA's Kennedy Space Center to treat complex wastewaters with the goal of closing water and nutrient cycles on early planetary bases. The system combined the previously operated anaerobic membrane bioreactor and the phototrophic membrane bioreactor that have been detailed in presentations at previous ICES conferences. This newly combined system is able to treat complex wastewater with completely automated controls on a small footprint. The treatment of wastes in this APMBR is as follows: (1) the waste enters the anaerobic subsystem, where solids are hydrolyzed and carbon is removed via anaerobic digestion, (2) an ultrafiltration membrane is used to separate the solids and the recovered water, (3) the effluent from the anaerobic subsystem is fed to the phototrophic subsystem on command, (4) the algae–bacteria consortium aids in nitrification in the recovered water, and (5) an ultrafiltration membrane is used to separate the algae and the final recovered water. The recovered water from the APMBR is rich in nutrients, making it a sustainable source of fertilizer for downstream hydroponic systems. This conference paper will detail the design and operation of the APMBR as a bioregenerative alternative to physical–chemical systems or bag and storage systems. Data will be presented on subsystem water quality, membrane performance, and effluent quality. Overall, the APMBR has the ability to treat wastewater using a combination of biological and filtration technologies that allow for higher removal efficiencies, low consumable use, and small footprint.