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All sources NASA NTRS DOE OSTI

DOE OSTI2025

Compressibility and permeability of particulated non-recyclable municipal solid waste

Biofuels from non-recyclable municipal solid waste (NMSW) stand at the forefront of energy sustainability. However, their widespread adoption is hampered by persistent material handling issues stemming from the variability in NMSW material properties. An enhanced understanding of particulated NMSW properties, particularly compressibility and permeability, is essential to address the feedstock handling challenges and optimize the handling equipment. This study measures the compressibility and gas permeability of five streams of NMSW materials (i.e., rigid plastics, cardboard, thin film, paper, and foam) and their mixtures under different stress conditions. The results highlight the significant variability in compressibility and gas permeability among different streams, as well as the impacts of particle sizes. A semi-empirical model capable of predicting the gas permeability of NMSW mixtures is established and validated. Here, the results also highlight that reduced NMSW particle size helps promote consistency in NMSW feedstock’s physical and mechanical properties, which is favored for handling equipment design in waste-to-energy recovery facilities.

09 BIOMASS FUELS↗

NASA NTRS2013

Aerospace Fuels From Nonpetroleum Raw Materials

Recycling human metabolic and plastic wastes minimizes cost and increases efficiency by reducing the need to transport consumables and return trash, respectively, from orbit to support a space station crew. If the much larger costs of transporting consumables to the Moon and beyond are taken into account, developing waste recycling technologies becomes imperative and possibly mission enabling. Reduction of terrestrial waste streams while producing energy and/or valuable raw materials is an opportunity being realized by a new generation of visionary entrepreneurs; several relevant technologies are briefly compared, contrasted and assessed for space applications. A two-step approach to nonpetroleum raw materials utilization is presented; the first step involves production of supply or producer gas. This is akin to synthesis gas containing carbon oxides, hydrogen, and simple hydrocarbons. The second step involves production of fuel via the Sabatier process, a methanation reaction, or another gas-to-liquid technology, typically Fischer-Tropsch processing. Optimization to enhance the fraction of product stream relevant to transportation fuels via catalytic (process) development at NASA Glenn Research Center is described. Energy utilization is a concern for production of fuels whether for operation on the lunar or Martian surface, or beyond. The term green relates to not only mitigating excess carbon release but also to the efficiency of energy usage. For space, energy usage can be an essential concern. Another issue of great concern is minimizing impurities in the product stream(s), especially those that are potential health risks and/or could degrade operations through catalyst poisoning or equipment damage; technologies being developed to remove heteroatom impurities are discussed. Alternative technologies to utilize waste fluids, such as a propulsion option called the resistojet, are discussed. The resistojet is an electric propulsion technology with a powered thruster to vaporize and heat a propellant to high temperature, hot gases are subsequently passed through a converging-diverging nozzle expanding gases to supersonic velocities. A resistojet can accommodate many different fluids, including various reaction chamber (by-)products.

Palaszewski, Bryan A.↗

NASA NTRS2013

Aerospace Fuels from Nonpetroleum Raw Materials

Recycling human metabolic and plastic wastes minimizes cost and increases efficiency by reducing the need to transport consumables and return trash, respectively, from orbit to support a space station crew. If the much larger costs of transporting consumables to the Moon and beyond are taken into account, developing waste recycling technologies becomes imperative and possibly mission enabling. Reduction of terrestrial waste streams while producing energy and/or valuable raw materials is an opportunity being realized by a new generation of visionary entrepreneurs; several relevant technologies are briefly compared, contrasted and assessed for space applications. A two-step approach to nonpetroleum raw materials utilization is presented; the first step involves production of supply or producer gas. This is akin to synthesis gas containing carbon oxides, hydrogen, and simple hydrocarbons. The second step involves production of fuel via the Sabatier process, a methanation reaction, or another gas-to-liquid technology, typically Fischer- Tropsch processing. Optimization to enhance the fraction of product stream relevant to transportation fuels via catalytic (process) development at NASA GRC is described. Energy utilization is a concern for production of fuels whether for operation on the lunar or Martian surface, or beyond. The term "green" relates to not only mitigating excess carbon release but also to the efficiency of energy usage. For space, energy usage can be an essential concern. Other issues of great concern include minimizing impurities in the product stream(s), especially those that are potential health risks and/or could de-grade operations through catalyst poisoning or equipment damage; technologies being developed to remove heteroatom impurities are discussed. Alternative technologies to utilize waste fluids, such as a propulsion option called the resistojet, are discussed. The resistojet is an electric propulsion technology with a powered thruster to vaporize and heat a propellant to high temperature, hot gases are subsequently passed through a converging-diverging nozzle expanding gases to supersonic velocities. A resistojet can accommodate many different fluids, including various reaction chamber (by-)products.

Palaszewski, B. A.↗

NASA NTRS2011

Green Aerospace Fuels from Nonpetroleum Sources

Efforts to produce green aerospace propellants from nonpetroleum sources are outlined. The paper begins with an overview of feedstock processing and relevant small molecule or C1 chemistry. Gas-to-liquid technologies, notably Fischer-Tropsch (FT) processing of synthesis gas (CO and H2), are being optimized to enhance the fraction of product stream relevant to aviation (and other transportation) fuels at the NASA Glenn Research Center (GRC). Efforts to produce optimized catalysts are described. Given the high cost of space launch, the recycling of human metabolic and plastic wastes to reduce the need to transport consumables to orbit to support the crew of a space station has long been recognized as a high priority. If the much larger costs of transporting consumables to the Moon or beyond are taken into account, the importance of developing waste recycling systems becomes still more imperative. One promising way to transform organic waste products into useful gases is steam reformation; this well-known technology is currently being optimized by a Colorado company for exploration and planetary surface operations. Reduction of terrestrial waste streams while producing energy and/or valuable raw materials is an opportunity being realized by a new generation of visionary entrepreneurs. A technology that has successfully demonstrated production of fuels and related chemicals from waste plastics developed in Northeast Ohio is described. Technologies being developed by a Massachusetts company to remove sulfur impurities are highlighted. Common issues and concerns for nonpetroleum fuel production are emphasized. Energy utilization is a concern for production of fuels whether a terrestrial operation or on the lunar (or Martian) surface; the term green relates to not only mitigating excess carbon release but also to the efficiency of grid-energy usage. For space exploration, energy efficiency can be an essential concern. Other issues of great concern include minimizing impurities in the product stream(s), especially those that potential health risks and/or could degrade operations through catalyst poisoning or equipment damage. The potential impacts on future missions by such concerns are addressed in closing.

Hepp, Aloysius F.↗

DOE OSTI2026

Challenges and Opportunities in the Enzymatic Recycling of Nylons

Enzymatic depolymerization has the potential to contribute to nylon waste recycling. However, the implementation of a viable industrial process still lags far behind progress in enzymatic polyester recycling. Here we review the current biocatalytic nylon recycling landscape, highlighting biochemical, structural, and materials science barriers that currently limit depolymerization extents. We detail efforts to identify, engineer, and characterize new nylon depolymerases, where currently even the best biocatalysts rarely exceed ~1 wt% conversion of solid polymer to products. Based on our analyses, we suggest that limited substrate accessibility due to substrate crystallinity and hydrogen bonding, rather than intrinsic enzyme inefficiency or instability, is the primary bottleneck to enhanced depolymerization. Guided by successes in polyester enzymatic recycling, we outline a research roadmap combining nylonase engineering with polymer pretreatment, chemo-enzymatic cascades, and process analyses to accelerate development of viable enzymatic nylon recycling processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Chemical recycling of mixed textile waste

Globally, less than 0.5% of postconsumer textile waste is recycled, with the majority incinerated or ending up in landfills. Most postconsumer textiles are mixed fibers, complicating mechanical recycling due to material blends and contaminants. Here, we demonstrate the chemical conversion of postconsumer mixed textile waste using microwave-assisted glycolysis over a ZnO catalyst followed by solvent dissolution. This approach electrifies the process heat while allowing rapid depolymerization of polyester and spandex to their monomers in 15 minutes. A simple solvent dissolution enables the separation of cotton and nylon. We assess the quality of all components through extensive material characterization, discuss their potential for sustainable recycling, and provide a techno-economic analysis of the economic feasibility of the process.

Science & Technology - Other Topics↗

NASA NTRS1989

Analysis of an algae-based CELSS. I - Model development

A steady state chemical model and computer program have been developed for a life support system and applied to trade-off studies. The model is based on human demand for food and oxygen determined from crew metabolic needs. The model includes modules for water recycle, waste treatment, CO2 removal and treatment, and food production. The computer program calculates rates of use and material balance for food, O2, the recycle of human waste and trash, H2O, N2, and food production/supply. A simple noniterative solution for the model has been developed using the steady state rate equations for the chemical reactions. The model and program have been used in system sizing and subsystem trade-off studies of a partially closed life support system.

Holtzapple, Mark T.↗

NASA NTRS1989

Analysis of an algae-based CELSS. Part 1: model development

A steady state chemical model and computer program have been developed for a life support system and applied to trade-off studies. The model is based on human demand for food and oxygen determined from crew metabolic needs. The model includes modules for water recycle, waste treatment, CO2 removal and treatment, and food production. The computer program calculates rates of use and material balance for food. O2, the recycle of human waste and trash, H2O, N2, and food production supply. A simple non-iterative solution for the model has been developed using the steady state rate equations for the chemical reactions. The model and program have been used in system sizing and subsystem trade-off studies of a partially closed life support system.

Models, Chemical↗

NASA NTRS1993

Hydroponic Crop Production using Recycled Nutrients from Inedible Crop Residues

The coupling of plant growth and waste recycling systems is an important step toward the development of bioregenerative life support systems. This research examined the effectiveness of two alternative methods for recycling nutrients from the inedible fraction (residue) of candidate crops in a bioregenerative system as follows: (1) extraction in water, or leaching, and (2) combustion at 550 C, with subsequent reconstitution of the ash in acid. The effectiveness of the different methods was evaluated by (1) comparing the percent recovery of nutrients, and (2) measuring short- and long-term plant growth in hydroponic solutions, based on recycled nutrients.

Garland, Jay L.↗

NASA NTRS1996

A bioreactor system for the nitrogen loop in a Controlled Ecological Life Support System

As space missions become longer in duration, the need to recycle waste into useful compounds rises dramatically. This problem can be addressed by the development of Controlled Ecological Life Support Systems (CELSS) (i.e., Engineered Closed/Controlled Eco-Systems (ECCES)), consisting of human and plant modules. One of the waste streams leaving the human module is urine. In addition to the reclamation of water from urine, recovery of the nitrogen is important because it is an essential nutrient for the plant module. A 3-step biological process for the recycling of nitrogenous waste (urea) is proposed. A packed-bed bioreactor system for this purpose was modeled, and the issues of reaction step segregation, reactor type and volume, support particle size, and pressure drop were addressed. Based on minimization of volume, a bioreactor system consisting of a plug flow immobilized urease reactor, a completely mixed flow immobilized cell reactor to convert ammonia to nitrite, and a plug flow immobilized cell reactor to produce nitrate from nitrite is recommended. It is apparent that this 3-step bioprocess meets the requirements for space applications.

NASA Discipline Number 61-10↗

DOE OSTI2026

Effect of polymer structure and material properties on mechanochemical reaction environments for polymer recycling

Plastic waste accumulation necessitates innovative recycling approaches to achieve sustainability goals. Mechanochemical depolymerization offers a solvent-free, energy-efficient route to convert polymers into valuable monomers. In addition to their chemical properties, the way that polymers absorb kinetic energy is a key parameter of any mechanochemical process. This perspective explores the principles underpinning mechanochemical recycling, emphasizing how deformation and localized transient heating mediate energy transfer between impacts and localized excitations. Key factors such as polymer crystallinity, molecular weight, viscoelasticity, and thermal effects are analyzed to elucidate their role in energy transfer mechanisms during ball milling. This work establishes a foundational framework for the design and optimization of mechanochemical recycling by connecting polymer response to mechanical energy with the intention to improve depolymerization efficiency. Future research opportunities are outlined to advance the integration of polymer science and mechanochemistry for scalable, sustainable plastic upcycling.

ball mill↗

NASA NTRS1985

Current Concepts and Future Directions of CELSS

Bioregenerative life support systems for use in space were studied. Concepts of such systems include the use of higher plants and/or microalgae as sources of food, potable water and oxygen, and as sinks for carbon dioxide and metabolic wastes. Recycling of materials within the system will require processing of food organism and crew wastes using microbiological and/or physical chemical techniques. The dynamics of material flow within the system will require monitoring, control, stabilization and maintenance imposed by computers. Studies included higher plant and algal physiology, environmental responses, and control; flight experiments for testing responses of organisms to weightlessness and increased radiation levels; and development of ground based facilities for the study of recycling within a bioregenerative life support system.

Macelroy, R. D.↗

DOE OSTI2026

ClassNMSW- a real-time classification approach for non-recycled municipal solid waste using hyperspectral imaging

Real-time classification of non-recycled municipal solid waste (NMSW) is essential for efficient valorization. This study introduces ClassNMSW, a comprehensive framework for classifying 22 NMSW subclasses under industrial constraints by using hyperspectral imaging (HSI). A primary innovation of this work is the development of a variance-controlled spectral extraction algorithm. Unlike traditional methods that rely on simple averaging, this approach systematically investigates the extent of pixel extraction to minimize the loss of critical chemical information while maximizing data reduction thus ensuring high spectral fidelity with low computational cost. The approach developed in this work integrates automated, computer-vision-based background removal, eliminating the need for the manual thresholding common in current literature. To resolve ambiguities among chemically similar subclasses, a tiered classification and multi-camera fusion strategy (NIR17 and NIR22) is implemented. Results demonstrate that ClassNMSW achieves an object-wise weighted accuracy of 98.70% for single-sensor configurations and 100% under sensor fusion. A novel rolling-window strategy satisfies desired end-to-end latency of <2 s, satisfying the strict deterministic requirements of high-speed industrial sorting environments. The ClassNMSW framework provides a scalable foundation for advancing circularity and resource recovery in large-scale waste valorization operations.

99 - GENERAL AND MISCELLANEOUS↗

NASA NTRS2001

Physical-Chemical Solid Waste Processing for Space Missions at Ames Research Center

As space missions become longer in duration and reach out to more distant locations such as Mars, solids waste processing progresses from storage technologies to reclamation technologies. Current low Earth orbit technologies consist of store-and dispose to space or return to Earth. Fully regenerative technologies recycle wastes. The materials reclaimed from waste can be used to provide the basic materials to support plant growth for food including carbon dioxide, water, and nutrients. Other products can also be reclaimed from waste such as hydrocarbons and activated carbon. This poster describes development at Ames Research Center of a process to make activated carbon from space mission wastes and to make an incineration system that produces clean flue gas. Inedible biomass and feces contain hydrocarbons in a form that can be pyrolyzed and converted to activated carbon. The activated carbon can then be used to clean up contaminants from various other life support systems; in particular, the activated carbon can be used regeneratively to remove NOx from incinerator flue gas. Incinerator flue gas can also be cleaned up by the use of reductive and oxidative catalysts. A catalytic incinerator flue gas cleanup system has been developed at ARC that produces flue gas clean enough (with the exception of carbon dioxide) to meet the Space Minimum Allowable Concentration limits for human exposure.

Fisher, John W.↗

NASA NTRS1990

Plants and men in space - A new field in plant physiology

Results are presented on a comparison of nutritional values of and human psychological responses to algae and of higher plants considered for growth as food on long-term missions in space, together with the technological complexities of growing these plants. The comparison shows the advantages of higher plants, with results suggesting that a high level of material recycling can be obtained. It is noted that the issue of space gravity may be not a major problem for plants because of the possibility that phototropism can provide an alternative sense of direction. Problems of waste recycling can be solved in association with plant cultivation, and a high degree of autonomy of food production can be obtained.

Andre, M.↗

NASA NTRS1995

Marshall Space Flight Center solid waste characterization and recycling improvement study

The MSFC Facilities Office, which is responsible for disposing of all waste generated by MSFC, issued a delivery order to the University of Alabama in Huntsville (UAH) to characterize current MSFC waste streams and to evaluate their existing recycling program. The purpose of the study was to define the nature, quantity, and types of waste produced and to generate ideas for improving the present recycling program. Specifically, the following tasks were to be performed: Identify various surplus and waste materials--as identified by the Contracting Officer's Technical Representative (COTR)--by source, location, and type; Analyze MSFC's current methods for handling, storage, transport, and disposition of waste and surplussed materials; Determine the composition of various surplus and waste materials as to type and quantities from various sources and locations; Analyze different methods for the disposition of various surplus and waste materials, including quality, quantity, preparation, transport cost, and value; Study possible alternatives to current methods of handling, storage, transport, and disposition of surplus and waste materials to improve the quality and quantities recycled or sold and to reduce and minimize the quantities of surplus and waste material currently being disposed of or stored; Provide recommendations for source and centralized segregation and aggregation of materials for recycling and/or disposition; and The analysis could include identification and laboratory level evaluation of methods and/or equipment, including capital costs, operating costs, maintenance requirements, life cycle and return on investment for systems to support the waste reduction program mission.

Eley, Michael H.↗

NASA NTRS2018

Water Walls Architecture: Massively Redundant And Highly Reliable Life Support For Long Duration Exploration Missions

The Water Wall concept proposes a system for structural elements that provide,thermal, radiation, water, solids and air treatment functions which are placed at the periphery of inflatable or rigid habitats. It also provides novel and potentially game changing mass reduction and reuse options for radiation protection. The approach would allow water recycling, air treatment, thermal control, and solids residuals treatment and recycling to be removed from the usable habitat volume, and placed in the walls by way of a radiation shielding water wall. It would also provide a mechanism to recover and reuse water treatment (solids) residuals to strengthen the habitat shell and a method of deriving radiation shielding from wastes generated on orbit. Water wall treatment elements would be a much-enlarged version of the commercially available hydration bags. Some water bags may have pervaporation membranes facing outward, which would provide the ability to remove H20, C02 and trace organics from the atmosphere and some would have hydrophobic internal membranes which would provide water, and waste recycling and some power generation.

Water Recycling↗

NASA NTRS1995

Technology transfer into the solid propulsion industry

This paper is a survey of the waste minimization efforts of industries outside of aerospace for possible applications in the manufacture of solid rocket motors (SRM) for NASA. The Redesigned Solid Rocket Motor (RSRM) manufacturing plan was used as the model for processes involved in the production of an SRM. A literature search was conducted to determine the recycling, waste minimization, and waste treatment methods used in the commercial sector that might find application in SRM production. Manufacturers, trade organizations, and professional associations were also contacted. Waste minimization efforts for current processes and replacement technologies, which might reduce the amount or severity of the wastes generated in SRM production, were investigated. An overview of the results of this effort are presented in this paper.

Campbell, Ralph L.↗