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At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Chemical Recycling of Mixed Plastics in Electronic Waste Using Solvent-Based Processing

Currently, less than 20% of electronic waste (E-waste) produced in the U.S. is recycled. To improve the recycling rate of E-waste, the study aimed to: (1) identify the major plastics found within electronic shredder residue (ESR), (2) design solvents and processing conditions capable of separating out 90% of the plastic in ESR, and (3) estimate the energy efficiency of the solvent-based process developed. Preliminary screening showed 25 wt.% of the ESR was composed of plastics, with two polymers dominating the sorted plastic fraction—polystyrene (PS, 40 wt.%) and acrylonitrile butadiene styrene (ABS, 25 wt.%). Subsequently, solvents and anti-solvents were screened using Hansen Solubility Parameter Theory for PS, ABS, and ESR dissolution. The pre-screening results showed dichloromethane (DCM) and tetrahydrofuran (THF) as the most effective solvents for PS and ABS, with methanol (MeOH) and ethylene glycol (EG) as the most effective anti-solvents. By optimizing the dissolution time and the solvents used, the highest polymer dissolution yield (99 wt.%) was achieved using DCM for 48 h. Both MeOH and EG precipitated 71 wt.% of the polymer fraction of ESR. EG removed more phosphorus containing flame retardants (94 wt.%) than MeOH (69 wt.%). Energy analysis indicated that the solvent-based processes could save 25–60% of the embodied energy for PS and ABS. Characterization showed that the solvent-based processing could preserve the high molecular weight fraction of the polymers while removing flame retardants at the same time. The results from this study prove the potential of solvent-based processing to produce secondary plastic materials from E-waste for cross-industry reuse.

Anderson, Lester↗
DOE OSTI2021

Direct Recycling R&D at the ReCell Center

The expected rapid growth in electric vehicle deployment will inevitably be followed by a corresponding rise in the supply of end-of-life vehicles and their lithium-ion batteries (LIBs). The batteries may be reused, but will eventually be spent and provide a potential domestic resource that can help supply materials for future battery production. However, commercial recycling processes depend on profits from recovery of cobalt, use of which is being reduced in new cathode chemistries. The U.S. Department of Energy, therefore, established the ReCell Center in early 2019 to develop robust LIB recycling technology that would be economical even for batteries that contain no cobalt. The central feature of the technology is recovery of the cathode material with its unique crystalline cathode morphology intact in order to retain its value and functionality. Other materials are recovered as well in order to maximize revenues and minimize waste-handling costs. Analysis and modeling serve to evaluate and compare process options so that we can identify those that will be most economical while still minimizing energy use and environmental impacts. This paper provides background and describes highlights of the center’s first 2 years of operation.

Gaines, Linda (ORCID:0000000237263387)↗
DOE OSTI2026

New Enzymes for Plastics Recycling from Biosensor-Guided Evolution and Machine Learning: Cooperative Research and Development Final Report, CRADA Number CRD-23-24335

The Agile BioFoundry (ABF) is a consortium of national laboratories dedicated to accelerating biomanufacturing and enabling the bioeconomy. The ABF operates a flexible biotechnology platform that can adjust to the needs of numerous government, academic, and industrial partners, thus enabling them to rapidly develop and optimize the production of a wide range of bioproducts. In this project, the ABF partnered with Birch Biosciences, Inc. to use ABF technology to assist in the development of high-performance enzymes that enable circular, sustainable recycling of poly(ethylene terephthalate) (PET) plastics. A primary goal of this project is to enable cost-effective, high yield, sustainable recycling of PET plastic packaging products.

09 BIOMASS FUELS↗
NASA NTRS1973

Complex permittivity measurements during high temperature recycling of space shuttle antenna window and dielectric heat shield materials

The research performed and the data obtained on candidate space shuttle antenna window and heat shield materials are presented. The measurement technique employs a free-space focused beam microwave bridge for obtaining RF transmission data, and a device which rotates a sample holder which is heated on one side by natural gas-air flames. The surface temperature of each sample is monitored by IR pyrometry; embedded and rear surface thermocouples are also used in obtaining temperature data. The surface of the sample undergoing test is subjected to approximately the same temperature/time profile that occurs at a proposed antenna position on the space shuttle as it re-enters. The samples are cycled through ten of these temperature profiles to determine the recycling effects. Very little change was noted in the materials due to the recycling.

Bassett, H. L.↗
NASA NTRS1981

Ion-exchange chromatography separation applied to mineral recycle in closed systems

As part of the controlled ecological life support system (CELSS) program, a study is being made of mineral separation on ion-exchange columns. The purpose of the mineral separation step is to allow minerals to be recycled from the oxidized waste products of plants, man, and animals for hydroponic food production. In the CELSS application, relatively large quantities of minerals in a broad concentration range must be recovered by the desired system, rather than the trace quantities and very low concentrations treated in analytical applications of ion-exchange chromatography. Experiments have been carried out to assess the parameters pertinent to the scale-up of ion-exchange chromatography and to determine feasibility. Preliminary conclusions are that the column scale-up is in a reasonable size range for the CELSS application. The recycling of a suitable eluent, however, remains a major challenge to the suitability of using ion exchange chromatography in closed systems.

Ballou, E.↗
NASA NTRS1982

Plant growth and mineral recycle trade-offs in different scenarios for a CELSS

Data for hydroponic plant growth in a manned system test is combined with nutritional recommendations to suport trade-off calculations for closed and partially closed life support system scenarios. Published data are used as guidelines for the masses of mineral nutrients needed for higher plant production. The results of calculations based on various scenarios are presented for various combinations of plant growth chamber utilization and fraction of mineral recycle. Estimates are made of the masses of material needed to meet human nutritional requirements in the various scenarios. It appears that food production from a plant growth chamber with mineral recycle is favorable to reduction of the total launch weight in missions exceeding 3 years.

Ballou, E. V.↗
NASA NTRS1988

Recycling of lower continental crust through foundering of cumulates from contaminated mafic intrusions

A mechanism is presented for recycling of lower continental material back into the mantle. Picritic magmas, possible parental to volumious continental volcanics such as the Karoo and Deccan, became trapped at the Moho, where they interacted with and become contaminated by lower crustal materials. Upon crystallization, the magmas differentiated into lower ultramafic cumulate zones and upper gabbroic-anorthositic zones. The ultramafic cumulates are denser than underlying mantle and sink, carrying lower crustal components as trapped liquid, as xenoliths or rafts, and as constituents of cumulate minerals. This model provides a potentially significant crust-mantle differentiation mechanism, and may also represent a contributing factor in crustal recycling, possibly important in producing some OIB reservoirs.

Arndt, Nicholas T.↗
NASA NTRS1991

Atmospheric water vapor transport: Estimation of continental precipitation recycling and parameterization of a simple climate model

The advective transport of atmospheric water vapor and its role in global hydrology and the water balance of continental regions are discussed and explored. The data set consists of ten years of global wind and humidity observations interpolated onto a regular grid by objective analysis. Atmospheric water vapor fluxes across the boundaries of selected continental regions are displayed graphically. The water vapor flux data are used to investigate the sources of continental precipitation. The total amount of water that precipitates on large continental regions is supplied by two mechanisms: (1) advection from surrounding areas external to the region; and (2) evaporation and transpiration from the land surface recycling of precipitation over the continental area. The degree to which regional precipitation is supplied by recycled moisture is a potentially significant climate feedback mechanism and land surface-atmosphere interaction, which may contribute to the persistence and intensification of droughts. A simplified model of the atmospheric moisture over continents and simultaneous estimates of regional precipitation are employed to estimate, for several large continental regions, the fraction of precipitation that is locally derived. In a separate, but related, study estimates of ocean to land water vapor transport are used to parameterize an existing simple climate model, containing both land and ocean surfaces, that is intended to mimic the dynamics of continental climates.

Brubaker, Kaye L.↗
NASA NTRS1992

Coupling plant growth and waste recycling systems in a controlled life support system (CELSS)

The development of bioregenerative systems as part of the Controlled Ecological Life Support System (CELSS) program depends, in large part, on the ability to recycle inorganic nutrients, contained in waste material, into plant growth systems. One significant waste (resource) stream is inedible plant material. This research compared wheat growth in hydroponic solutions based on inorganic salts (modified Hoagland's) with solutions based on the soluble fraction of inedible wheat biomass (leachate). Recycled nutrients in leachate solutions provided the majority of mineral nutrients for plant growth, although additions of inorganic nutrients to leachate solutions were necessary. Results indicate that plant growth and waste recyling systems can be effectively coupled within CELSS based on equivalent wheat yield in leachate and Hoagland solutions, and the rapid mineralization of waste organic material in the hydroponic systems. Selective enrichment for microbial communities able to mineralize organic material within the leachate was necessary to prevent accumulation of dissolved organic matter in leachate-based solutions. Extensive analysis of microbial abundance, growth, and activity in the hydroponic systems indicated that addition of soluble organic material from plants does not cause excessive microbial growth or 'biofouling', and helped define the microbially-mediated flux of carbon in hydroponic solutions.

Garland, Jay L.↗
NASA NTRS1993

Microbiological test results of the environmental control and life support systems vapors compression distillation subsystem recycle tank components following various pretreatment protocols

Microbiological samples were collected from the recycle tank of the vapor compression distillation (VCD) subsystem of the water recovery test at NASA MSFC following a 68-day run. The recycle tank collects rejected urine brine that was pretreated with a commercially available oxidant (Oxone) and sulfuric acid and pumps it back to the processing component of the VCD. Samples collected included a water sample and two swab samples, one from the particulate filter surface and a second from material floating on the surface of the water. No bacteria were recovered from the water sample. Both swab samples contained a spore-forming bacterium, Bacillus insolitus. A filamentous fungus was isolated from the floating material. Approximately 1 month after the pretreatment chemicals were changed to sodium hypochlorite and sulfuric acid, a swab of the particulate filter was again analyzed for microbial content. One fungus was isolated, and spore-forming bacteria were observed. These results indicate the inability of these pretreatments to inhibit surface attachment. The implications of the presence of these organisms are discussed.

Huff, Tim↗
NASA NTRS1992

Recycling and source reduction for long duration space habitation

A direct mathematical approach has been established for characterizing the performance of closed-loop life support systems. The understanding that this approach gives clearly illustrates the options available for increasing the performance of a life support system by changing various parameters. New terms are defined and utilized, such as Segregation Factor, Resource Recovery Efficiency, Overall Reclamation Efficiency, Resupply Reduction Factor, and Life Support Extension Factor. The effects of increases in expendable system supplies required due to increases in life support system complexity are shown. Minimizing resupply through increased recycling and source reduction is illustrated. The effects of recycling upon resupply launch cost is also shown. Finally, material balance analyses have been performed based on quantity and composition data for both supplies and wastes, to illustrate the use of this approach by comparing ten different closed-loop life support system cases.

Hightower, T. M.↗
NASA NTRS1993

Estimation of continental precipitation recycling

The total amount of water that precipitates on large continental regions is supplied by two mechanisms: 1) advection from the surrounding areas external to the region and 2) evaporation and transpiration from the land surface within the region. The latter supply mechanism is tantamount to the recycling of precipitation over the continental area. The degree to which regional precipitation is supplied by recycled moisture is a potentially significant climate feedback mechanism and land surface-atmosphere interaction, which may contribute to the persistence and intensification of droughts. Gridded data on observed wind and humidity in the global atmosphere are used to determine the convergence of atmospheric water vapor over continental regions. A simplified model of the atmospheric moisture over continents and simultaneous estimates of regional precipitation are employed to estimate, for several large continental regions, the fraction of precipitation that is locally derived. The results indicate that the contribution of regional evaporation to regional precipitation varies substantially with location and season. For the regions studied, the ratio of locally contributed to total monthly precipitation generally lies between 0. 10 and 0.30 but is as high as 0.40 in several cases.

Brubaker, Kaye L.↗
NASA NTRS1994

Subduction and volatile recycling in Earth's mantle

The subduction of water and other volatiles into the mantle from oceanic sediments and altered oceanic crust is the major source of volatile recycling in the mantle. Until now, the geotherms that have been used to estimate the amount of volatiles that are recycled at subduction zones have been produced using the hypothesis that the slab is rigid and undergoes no internal deformation. On the other hand, most fluid dynamical mantle flow calculations assume that the slab has no greater strength than the surrounding mantle. Both of these views are inconsistent with laboratory work on the deformation of mantle minerals at high pressures. We consider the effects of the strength of the slab using two-dimensional calculations of a slab-like thermal downwelling with an endothermic phase change. Because the rheology and composition of subducting slabs are uncertain, we consider a range of Clapeyron slopes which bound current laboratory estimates of the spinel to perovskite plus magnesiowustite phase transition and simple temperature-dependent rheologies based on an Arrhenius law diffusion mechanism. In uniform viscosity convection models, subducted material piles up above the phase change until the pile becomes gravitationally unstable and sinks into the lower mantle (the avalanche). Strong slabs moderate the 'catastrophic' effects of the instabilities seen in many constant-viscosity convection calculations; however, even in the strongest slabs we consider, there is some retardation of the slab descent due to the presence of the phase change.

King, S. D.↗
NASA NTRS1993

Performance of high-recovery recycling reverse osmosis with wash water

Inclusion of a recycling loop for partially-desalted water from second-stage reverse-osmosis permeate has been shown useful for achieving high-recovery at moderate applied pressures. This approach has now been applied to simulated wash waters, to obtain data on retention by the membranes of solutes in a mixture comparable to anticipated spacecraft hygiene wastewaters, and to generate an estimate of the maximum concentration that can be expected without causing membrane fouling. A first experiment set provides selectivity information from a single membrane and an Igepon detergent, as a function of final concentration. A reject concentration of 3.1% Total Organic Carbon has been reached, at a pressure of 1.4 Mega Pascals, without membrane fouling. Further experiments have generated selectivity values for the recycle configuration from two washwater simulations, as a function of applied pump pressure. Reverse osmosis removal has also been tested for washwater containing detergent formulated for plant growth compatibility (containing nitrogen, phosphorous and potassium functional groups.)

Herrmann, Cal C.↗
NASA NTRS1996

Plastic Recycling Experiments in Materials Education

The objective of this project was to introduce a series of plastic recycling experiments to students in materials-related courses such as materials science, material technology and materials testing. With the plastic recycling experiments, students not only can learn the fundamentals of plastic processing and properties as in conventional materials courses, but also can be exposed to the issue of materials life cycle and the impact on society and environment.

Liu, Ping↗
NASA NTRS1996

Precipitation Recycling

The water cycle regulates and reflects natural variability in climate at the regional and global scales. Large-scale human activities that involve changes in land cover, such as tropical deforestation, are likely to modify climate through changes in the water cycle. In order to understand, and hopefully be able to predict, the extent of these potential global and regional changes, we need first to understand how the water cycle works. In the past, most of the research in hydrology focused on the land branch of the water cycle, with little attention given to the atmospheric branch. The study of precipitation recycling which is defined as the contribution of local evaporation to local precipitation, aims at understanding hydrologic processes in the atmospheric branch of the water cycle. Simply stated, any study on precipitation recycling is about how the atmospheric branch of the water cycle works, namely, what happens to water vapor molecules after they evaporate from the surface, and where will they precipitate?

Eltahir, Elfatih A. B.↗
NASA NTRS2002

Precipitation Recycling and the Vertical Distribution of Local and Remote Sources of Water for Precipitation

Precipitation recycling is defined as the amount of water that evaporates from a region that precipitates within the same region. This is also interpreted as the local source of water for precipitation. In this study, the local and remote sources of water for precipitation have been diagnosed through the use of passive constituent tracers that represent regional evaporative sources along with their transport and precipitation. We will discuss the differences between this method and the simpler bulk diagnostic approach to precipitation recycling. A summer seasonal simulation has been analyzed for the regional sources of the United States Great Plains precipitation. While the tropical Atlantic Ocean (including the Gulf of Mexico) and the local continental sources of precipitation are most dominant, the vertically integrated column of water contains substantial water content originating from the Northern Pacific Ocean, which is not precipitated. The vertical profiles of regional water sources indicate that local Great Plains source of water dominates the lower troposphere, predominantly in the PBL. However, the Pacific Ocean source is dominant over a large portion of the middle to upper troposphere. The influence of the tropical Atlantic Ocean is reasonably uniform throughout the column. While the results are not unexpected given the formulation of the model's convective parameterization, the analysis provides a quantitative assessment of the impact of local evaporation on the occurrence of convective precipitation in the GCM. Further, these results suggest that local source of water is not well mixed throughout the vertical column.

Bosilovich, Michael G.↗
NASA NTRS1991

Plants for water recycling, oxygen regeneration and food production

During long-duration space missions that require recycling and regeneration of life support materials the major human wastes to be converted to usable forms are CO2, hygiene water, urine and feces. A Controlled Ecological Life Support System (CELSS) relies on the air revitalization, water purification and food production capabilities of higher plants to rejuvenate human wastes and replenish the life support materials. The key processes in such a system are photosynthesis, whereby green plants utilize light energy to produce food and oxygen while removing CO2 from the atmosphere, and transpiration, the evaporation of water from the plant. CELSS research has emphasized the food production capacity and efforts to minimize the area/volume of higher plants required to satisfy all human life support needs. Plants are a dynamic system capable of being manipulated to favour the supply of individual products as desired. The size and energy required for a CELSS that provides virtually all human needs are determined by the food production capacity. Growing conditions maximizing food production do not maximize transpiration of water; conditions favoring transpiration and scaling to recycle only water significantly reduces the area, volume, and energy inputs per person. Likewise, system size can be adjusted to satisfy the air regeneration needs. Requirements of a waste management system supplying inputs to maintain maximum plant productivity are clear. The ability of plants to play an active role in waste processing and the consequence in terms of degraded plant performance are not well characterized. Plant-based life support systems represent the only potential for self sufficiency and food production in an extra-terrestrial habitat.

NASA Discipline Life Support Systems↗