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Management of human feces and wastes is a major challenge in space vehicles due to the potential biohazards and malodorous compounds emanating during collection and storage of feces and wastes. To facilitate safe, yet realistic human waste management research, we have previously developed human fecal simulants for research activities. The odoriferous compounds in feces and wastes reduce the quality of life for astronauts, can reduce performance, and can even cause health problems. The major odoriferous compounds of concern belong to four groups of chemicals, volatile fatty acids, volatile sulfurous compounds, nitrogenous compounds and phenols. This paper attempts to review the problem of odor detection and odor control with advanced technology. There has been considerable progress in odor detection and control in the animal industry and in the dental profession.

Terraforming of Mars is the long-term goal of colonization of Mars. However, this process is likely to be a very slow process and conservative estimates involving a synergetic, technocentric approach suggest that it may take around 10,000 years before the planet can be parallel to that of Earth and where humans can live in open systems (Fogg, 1995). Hence, for the foreseeable future, any missions will require habitation within small confined habitats with high biomass to atmospheric mass ratios, thereby requiring that all wastes be recycled. Processing of the wastes will ensure predictability and reliability of the ecosystem and reduce resupply logistics. Solid wastes, though smaller in volume and mass than the liquid wastes, contain more than 90% of the essential elements required by humans and plants.

Pyrolysis is a very versatile waste processing technology which can be tailored to produce a variety of solid, liquid and/or gaseous products. The pyrolysis processing of pure and mixed solid waste streams has been under investigation for several decades for terrestrial use and a few commercial units have been built for niche applications. Pyrolysis has more recently been considered for the processing of mixed solid wastes in space. While pyrolysis units can easily handle mixed solid waste streams, the dependence of the pyrolysis product distribution on the component composition is not well known. It is often assumed that the waste components (e.g., food, paper, plastic) behave independently, but this is a generalization that can usually only be applied to the overall weight loss and not always to the yields of individual gas species.

A Microwave Enhanced Freeze Drying Solid Waste (MEFDSW) processor was delivered to NASA-Ames Research Center by Umpqua Company having been funded through a Small Business Innovative Research Phase II program. The prototype hardware was tested for its performance characteristics and for its functionality with the primary focus being the removal of water from solid wastes. Water removal from wastes enables safe storage of wastes, prevents microbes from growing and propagating using the waste as a substrate and has potential for recovery and reuse of the water. Other objectives included measurements of the power usage and a preliminary estimate of the Equivalent System Mass (ESM) value. These values will be used for comparison with other candidate water removal technologies currently in development.

A microwave powered solid waste stabilization and water recovery prototype was delivered to Ames Research Center through an SBIR Phase II contract awarded to Umpqua Research Company. The system uses a container capable of holding 5.7 dm3 volume of waste. The microwave power can be varied to operate either at full power (130 W) or in a variable mode from 0% and 100%. Experiments were conducted with different types of wastes (wet cloth, simulated feces/diarrheal wastes, wet trash and brine) at different levels of moisture content and dried under varying microwave power supply. This paper presents the experimental data. The results provide valuable insight into the different operation modes under which the prototype can be used to recover water from the wastes in a space environment. Further investigations and testing of the prototype are recommended.

The elemental composition of food consumed by astronauts is well defined. The major elements carbon, hydrogen, oxygen, nitrogen and sulfur are taken up in large amounts and these are often associated with the organic fraction (carbohydrates, proteins, fats etc) of human tissue. On the other hand, a number of the elements are located in the extracellular fluids and can be accounted for in the liquid and solid waste fraction of humans. These elements fall into three major categories - cationic macroelements (e.g. Ca, K, Na, Mg and Si), anionic macroelements (e.g. P, S and Cl and17 essential microelements, (e.g. Fe, Mn, Cr, Co, Cu, Zn, Se and Sr). When provided in the recommended concentrations to an adult healthy human, these elements should not normally accumulate in humans and will eventually be excreted in the different human wastes.

NASA Ames Research Center and Lawrence Berkeley National lab have completed a three-year joint NRA research project on the use of waste biomass to make a gaseous contaminant removal system. The objective of the research was to produce activated carbon from life support wastes and to use the activated carbon to adsorb and remove incineration flue gas contaminants such as NOx. Inedible biomass waste from food production was the primary waste considered for conversion to activated carbon. Previous research at NASA Ames has demonstrated the adsorption of both NOx and SO2 on activated carbon made from biomass and the subsequent conversion of adsorbed NOx to nitrogen and SO2 to sulfur. This paper presents the results testing the whole process system consisting of making, using, and regenerating activated carbon with relevant feed from an actual incinerator. Factors regarding carbon preparation, adsorption and regeneration are addressed.

Pyrolysis processing of solid waste in space will inevitably lead to carbon formation as a primary pyrolysis product. The amount of carbon depends on the composition of the starting materials and the pyrolysis conditions (temperature, heating rate, residence time, pressure). Many paper and plastic materials produce almost no carbon residue upon pyrolysis, while most plant biomass materials or human wastes will yield up to 20-40 weight percent on a dry, as-received basis. In cases where carbon production is significant, it can be stored for later use to produce CO2 for plant growth. Alternatively it can be partly gasified by an oxidizing gas (e.g., CO2, H2O, O2) in order to produce activated carbon. Activated carbons have a unique capability of strongly absorbing a great variety of species, ranging from SO2 and NOx, trace organics, mercury, and other heavy metals.

Pyrolysis is a very versatile waste processing technology which can be tailored to produce a variety of solid liquid and/or gaseous products. The main disadvantages of pyrolysis processing are: (1) the product stream is more complex than for many of the alternative treatments; (2) the product gases cannot be vented directly into the cabin without further treatment because of the high CO concentrations. One possible solution is to combine a pyrolysis step with catalytic oxidation (combustion) of the effluent gases. This integration takes advantage of the best features of each process, which is insensitivity to product mix, no O2 consumption, and batch processing, in the case of pyrolysis, and simplicity of the product effluent stream in the case of oxidation. In addition, this hybrid process has the potential to result in a significant reduction in Equivalent System Mass (ESM) and system complexity.

In this paper we have developed a unique approach to providing the elements required for crop production in a steady-state condition, which is essential for Space habitats. The approach takes into consideration human elemental requirements and crop requirements for healthy growth and develops a method for the calculation of the rates of nutrient uptake for the different elements for different crops. The uptake rates can be used to calculate the rate of nutrient supply required in the hydroponic solution. This approach ensures that crops produced will not have excessive levels of elements that may be harmful to humans. It also provides an opportunity to optimize the processes of crop production and waste processing through highly controlled feed rates.

This paper presents the results from a joint research initiative between NASA Ames Research Center and Lawrence Berkeley National lab. The objective of the research is to produce activated carbon from life support wastes and to use the activated carbon to adsorb and chemically reduce the NOx and SO2 contained in incinerator flue gas. Inedible biomass waste from food production is the primary waste considered for conversion to activated carbon. Results to date show adsorption of both NOx and SO2 in activated carbon made from biomass. Conversion of adsorbed NOx to nitrogen has also been observed.

Since the mid 1980s, NASA has developed advanced waste management technologies that collect and process waste. These technologies include incineration, hydrothermal oxidation, pyrolysis, electrochemical oxidation, activated carbon production, brine dewatering, slurry bioreactor oxidation, composting, NOx control, compaction, and waste collection. Some of these technologies recover resources such as water, oxygen, nitrogen, carbon dioxide, carbon, fuels, and nutrients. Other technologies such as the Waste Collection System (WCS - the commode) collect waste for storage or processing. The need for waste processing varies greatly depending upon the mission scenario. This paper reviews the waste management technology development activities conducted by NASA since the mid 1980s and explores the drivers that determine the application of these technologies to future missions.