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The growth of Swiss chard in compost, Mars regolith simulant, and mixtures thereof, was studied for application in Advanced Life Support (ALS) systems, particularly Mars/lunar based operations. The purpose was to begin characterizing a sustainable biomass production method based on compost derived from inedible biomass. Compost would serve both as a means of recycling plant nutrients while improving the physical qualities of regolith as a plant growth medium. An outpost’s cropping area could be expanded by blending a minimal amount of compost (scarce, initially imported resource) and a maximal amount of regolith (plentiful local resource), consistent with adequate crop yields. Swiss chard was selected for the study as it is an ALS crop candidate for which there are little data.

Distant and/or long-term missions, particularly Mars and lunar bases, will require a high degree of regenerative systems utilization. Bio-regenerative systems inherently lend themselves to integrative application, and can serve multiple processing functions in Advanced Life Support (ALS) systems. Striving for maximal use of bio-regenerative systems can reveal possibilities and relationships difficult to conceptualize within the context of a “unit process” methodology common to physico-chemical (P/C) systems. The required regenerative functions of biomass production and solid, liquid, and air processing are discussed, and a potential integrated ALS system scenario including “soil'based” plant production is developed to illustrate potential ramifications of biological (and P/C) system integration.

The use of biofilters for the control of air contaminants in Advanced Life Support (ALS) systems is currently being investigated by the Waste Processing and Resource Recovery research team of the New Jersey - NSCORT (NASA Specialized Center of Research and Training). Ammonia (NH3) was selected as a test air contaminant as it presents special challenges to the sustained operation of a biofilter. Ammonia loading to the ALS atmosphere will likely be from waste treatment (biological treatment of human, plant and food wastes) and food processing operations. This NH3 has the potential of causing adverse effects on plant growth and humans.

A current study is investigating the feasibility of using air treatment biofilters to remove ethylene from atmospheres of Advanced Life Support (ALS) systems for spacecraft or planetary habitat environments. Ethylene was selected as the contaminant because: 1) it partitions poorly in water, thus challenging the limits of biofilter performance; and 2) it is a plant growth regulator that can adversely affect plant growth even at concentrations as low as 40 parts per billion (ppb). Thus control of ethylene in a biomass production chamber (BPC) is of direct concern. In laboratory scale studies ethylene was removed from air to below a target level of 20 ppb, with 4 ppb being the lowest exit concentration observed. This performance (<20 ppb) was observed for 12 days, with exit concentrations gradually increasing to 70 - 100 ppb by day 55. The decreased level of performance was apparently due to nutrient (nitrogen) limitation.

Biological treatment technologies used in removing air pollutants are reviewed from the perspective of an Advanced Life Support System (ALSS). These are based on the capability of microbial communities to biodegrade complex and variable mixtures of organic and inorganic compounds, typically to innocuous end products. The technologies considered are biofilters, biotrickling filters and bioscrubbers, with emphasis on biofilters. Theoretical design aspects are outlined. Different bed media (matrices) are described. A list of compounds treated successfully, solely or in complex mixtures, is provided. A brief summary of our current research on the removal of ethylene and ammonia (model compounds) through biofiltration is included.