Browsing by Author "Wignarajah, Kanapathipillai"
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Item An Assessment of the Water Extraction Capabilities of the Heat Melt Compactor(44th International Conference on Environmental Systems, 2014-07-13) Alba, Richard; Harris, Linden; Wignarajah, Kanapathipillai; Fisher, John; Hummerick, Mary; Pace, Gregory; Delzeit, Lance; Larson, BrianThe Heat Melt Compactor (HMC), a waste management technology developed at the NASA Ames Research Center, was designed to process waste generated aboard spacecraft. The device compacts, encapsulates and sterilizes the waste in preparation for onboard storage. In addition, the unit removes and recovers water, which is ultimately recycled1, rendering the encapsulated waste inhospitable to microbial contaminants. Initial studies indicate that the HMC is capable of removing and capturing 90 to 98% of the water contained in the process waste sample.2 The nineteen experiments conducted at ARC described in this paper attempt to refine, quantify and define the limitations of the Heat Melt Compactor's dewatering and water collection capabilities. The amount of water in the initial waste sample was measured and found to be 19.04% by weight for batches made at ARC and 20.45% for those made at KSC. This was less than the percentage predicted from the standard waste model. The amount of water recovered and collected varied from 12.9 to 98.4% of initial water contained in the waste. For the six tiles tested, the amount of water remaining in the tiles after processing ranged from 6.97 to 37.67%. The water activity for five of these tiles averaged 0.472; all of these issues play a significant role in the survival and propagation of microorganisms. Water activity values below 0.6 inhibit microbial growth. Significant correlation was found to exist between Percent Water Recovery, Percent Expected Water Encapsulated in Tile and Water Activity, the latter two of which are inversely proportional to water recovered. Percent Water Recovery, since it is easily computed, can be used to predict the other two values.Item An Examination of Trash Ozonation(44th International Conference on Environmental Systems, 2014-07-13) Lee, Jeffrey M.; Fisher, John W.; Harris, Linden C.; Wignarajah, Kanapathipillai; Alba, Richard G.We report on the potential for using dissolved ozone in water – ozonation – to oxidize trash and waste. An SBIR Phase II pilot scale ozonation system developed by TDA Research, Inc. was tested for use in oxidizing various mixtures of trash and wastes that included plastics, foodstuff, packaging, cloth, paper, fecal simulant, and pre-processed Heat Melt Compactor tiles. In addition to pure liquid phase ozonation, we also modified and tested the system for gas phase ozone oxidation in saturated water vapor with a heating element to promote smoldering. These tests were conducted as part of the NASA “Trash to Gas” project to identify candidate technologies for processing low value trash and waste into higher value product gasses.Item Processing of Packing Foams Using Heat Melt Compaction(44th International Conference on Environmental Systems, 2014-07-13) Harris, Linden; Alba, Richard; Wignarajah, Kanapathipillai; Fisher, John; Monje, Oscar; Maryatt, Brandon; Broyan, James; Pace, GregoryFoam is used extensively as packing material for items sent to the International Space Station (ISS). Although lightweight, foam is bulky and can occupy a large fraction of the limited ISS volume. Four chemically distinct foams have been used on the ISS. In descending order of current usage, these are Plastazote > Zotek > Minicel > Pyrell. Processing foam with the Heat Melt Compactor (HMC), a solid waste treatment system, has been proposed to reduce the volume of foams stored on spacecraft. Prior to HMC testing, Thermogravimetric Analyses were conducted on the four foams as a precaution to ensure that the thermal decomposition temperatures were not within range of HMC operation (≤180°C). Pyrell was not tested with the HMC because it is known to release toxic compounds and comprises less than 1.5% of total foam usage on ISS resupply flights. Zotek, Minicel, Plastazote LD24FR (low density), and Plastazote LD45FR (high density) were processed with the HMC at 130, 150 and 170°C. Volume was reduced by 82.6% on average (n=19; std dev=4.88). Hydrocarbons and several other compounds emitted during foam processing were measured using a Total Hydrocarbon Analyzer and FTIR. Effects of process temperature and foam type on exhaust composition are discussed. Feeding of foams into the limited size opening of the HMC compaction chamber is likely to be a challenge, particularly in microgravity. Some suggestions are proposed to facilitate feeding foam into the HMC. Processing packing foam with the HMC has been shown to substantially reduce foam volume, and also has the potential benefit of producing radiation-shielding foam tiles.Item Shakedown Test of the Orbital Technologies PMWC for Performance in Treating Solid Wastes(45th International Conference on Environmental Systems, 2015-07-12) Wignarajah, Kanapathipillai; Alba, Richard; Fisher, John W.; Richardson, Tra-My JustineHeat melt compaction of space mission trash is a technology that has been under development by NASA for a number of years. Goals for heat melt compaction include compaction and volume reduction, recovery of water, disinfection of the wastes, prevention of growth of microbes (drying) in the wastes, control of contaminants in the effluent gases, and preparation of tiles for radiation shielding. A prototype heat melt compactor, the Plastic Melt Waste Compactor (PMWC), was delivered as part of a Small Business Innovative Research project by Orbital Technologies Corporation (Orbitec) to NASA Ames Research Center in June of 2014. Goals specific to the Orbitec PMWC development focused on chamber size, nonstick surface treatments, water recovery, and volume reduction. Although not an area of emphasis for the Orbitec PMWC development effort, disinfection is important in order to prevent microbial growth on trash tiles that are stored or used for radiation shielding from becoming a health hazard to the crew. This paper presents results of shakedown tests of the PMWC with a focus on the disinfection performance of the delivered hardware.Item Space Applications of Torrefaction Processing(45th International Conference on Environmental Systems, 2015-07-12) Serio, Michael A.; Cosgrove, Joseph E.; Wójtowicz, Marek A.; Lee, Jeffrey; Wignarajah, Kanapathipillai; Fisher, JohnA recent study addressed the technical feasibility of a torrefaction (mild pyrolysis) processing system that could be used to sterilize feces and related cellulosic biomass wastes (food, paper, wipes, and clothing) in space, while simultaneously recovering moisture, producing additional water, and small amounts of other useful products (e.g., CO2, CO, and CH4). This work was done using bench scale torrefaction processing units and examined different modes of heating (conventional and microwave). The amounts of solid vs. gas plus liquid products could be controlled by adjusting the torrefaction conditions, especially the final temperature and holding time. The solid char product from a fecal simulant was a dry, free flowing powder that did not support bacterial growth and was hydrophobic relative to the starting material. The proposed torrefaction approach has potential benefits to NASA in allowing for solid waste sterilization and stabilization, planetary protection, in-situ resource utilization (ISRU) and/or production of chemical feedstocks and carbon materials. In particular, the torrefaction char residue has several potential applications in space. These include production of activated carbon, a nutrient-rich substrate for plant growth, construction material, radiation shielding, storage of elemental carbon, hydrogen, or oxygen, and fuel gas (CH4, CO, and H2) production. The current paper provides additional torrefaction data and analysis. It also addresses the potential space applications of torrefaction processing, how it compares to other approaches to solid waste management, its applicability to a range of cellulosic biomass materials, and how the technology could be integrated with existing advanced life support technologies, such as the Heat Melt Compactor (HMC) or the Universal Waste Management System (UWMS).Item Torrefaction Processing of Spacecraft Solid Wastes(44th International Conference on Environmental Systems, 2014-07-13) Serio, Michael A.; Cosgrove, Joseph E.; Wójtowicz, Marek A.; Lee, Jeffrey; Wignarajah, Kanapathipillai; Fisher, JohnNew technology is needed to collect, stabilize, recover useful materials, and store human fecal waste and other spacecraft solid wastes for long duration space missions. The system should also require minimal crew interactions, low energy demands, and tolerate mixed or contaminated waste streams. The current study addressed the technical feasibility of a torrefaction (mild pyrolysis) processing system that could be used to sterilize feces and related cellulosic biomass wastes (food, paper, wipes, and clothing), while simultaneously recovering moisture and producing small amounts of other useful products (e.g., CO2, CO, and CH4). This work was done using bench scale torrefaction processing units and examined different modes of heating (conventional and microwave) in laboratory studies. A fecal simulant was tested over a range of process conditions (temperature, holding time and atmosphere), along with selected runs with a sludge derivative (Milorganite), cotton fabric, and wipes. The results demonstrated that microwave heating allowed for careful control of torrefaction conditions for the fecal simulant. The net result was complete recovery of moisture, some additional water production, a modest reduction of the dry solid mass, and small amounts of gas (CO2, CO, and CH4) and hydrocarbon liquid production. The amounts of solid vs. gas plus liquid products can be controlled by adjusting the torrefaction conditions, especially the final temperature and holding time. The solid char product from the fecal simulant was a dry, free flowing powder that did not support bacterial growth and was hydrophobic relative to the starting material. The proposed torrefaction approach has potential benefits to NASA in allowing for solid waste sterilization and stabilization, planetary protection, in-situ resource utilization (ISRU) and/or production of chemical feedstocks and carbon materials. In particular, the torrefaction char residue has several potential applications in space. These include production of activated carbon, a nutrient-rich substrate for plant growth, construction material, radiation shielding, storage of elemental carbon, hydrogen, or oxygen, and fuel gas (CH4, CO, and H2) production.