ognizant Communication Corporation

LIFE SUPPORT & BIOSPHERE SCIENCE

ABSTRACTS
VOLUME 7, NUMBER 4

Life Support & Biosphere Science, Vol. 7, pp. 283-290
1069-9422/01 $20.00 + .00
Copyright © 2001 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Intracanopy Lighting Reduces Electrical Energy Utilization by Closed Cowpea Stands

J. M. Frantz, R. J. Joly, and C. A. Mitchell

Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907-1165

The high planting densities needed to grow edible biomass in sustainable space life support systems will create problems for planophile crops that form closed, self-shading canopies. The use of traditional overhead-lighting configurations will reduce the penetration of photosynthetically active radiation (PAR) into such canopies and will result in substantial shading of understory leaves. Intracanopy lighting, an irradiation approach that allows plants to grow around fixed arrays of low-intensity lamps, reduces overall energy expenditure for crop production by improving light distribution and interception throughout the canopy. Comparing different fluorescent lamp geometries within vegetative canopies of cowpea (Vigna unguiculata L. Walp) revealed great plasticity of leaf orientation to maximize absorption of PAR from lamps arrayed at various nontraditional angles. Varying the amount of photosynthetic energy available within canopies creates considerable potential to manipulate canopy productivity. Increasing lamp number 38% within cowpea canopies raised stand productivity 45%, reflecting the highly efficient interception and absorption of intracanopy PAR. However, combined above/within-canopy lighting did not increase overall PAR interception and vegetative yield, and productivity did not improve relative to the same input wattage of intracanopy lighting alone. Optimization of intracanopy lighting for crops to be used in future space life support systems will substantially reduce power and energy burdens for food-crop production.

Key words: Vigna unguiculata; Controlled environments; Crop production; Hydroponics; Photosynthetically active radiation; Yield efficiency

Address correspondence to C. A. Mitchell. Tel: (765) 494-1347; Fax: (765) 494-0391; E-mail: mitchell@hort.purdue.edu




Life Support & Biosphere Science, Vol. 7, pp. 291-299
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Copyright © 2001 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

On-Line Removal of Volatile Fatty Acids from CELSS Anaerobic Bioreactor Via Nanofiltration

Guillermo Colón1 and John C. Sager2

1University of Puerto Rico, Mayagüez Campus, Chemical Engineering Department, P.O. Box 9046, Mayagüez, PR 00681
2National Aeronautics and Space Administration, Mail Code MD-RES, J.F. Kennedy Space Center, FL 32899

The CELSS resource recovery system, which is a waste-processing system, uses aerobic and anaerobic bioreactors to recover plants nutrients and secondary foods from the inedible biomass. The anaerobic degradation of the inedible biomass, by means of culture of rumen bacteria, generates organic compounds such as volatile fatty acids (VFA) (acetic, propionic, butyric) and ammonia. The presence of VFA in the bioreactor medium at fairly low concentrations decreases the microbial population's metabolic reactions due to end-product inhibition. Technologies to remove VFA continuously from the bioreactor are of high interest. Several candidate technologies were analyzed, such as organic solvent liquid-liquid extraction, adsorption and/or ion exchange, dialysis, electrodialysis, and pressure-driven membrane separation processes. The proposed technique for the on-line removal of VFA from the anaerobic bioreactor was a nanofiltration membrane recycle bioreactor. In order to establish the nanofiltration process performance variables before coupling it to the bioreactor, a series of experiments was carried out using a 10,000 molecular weight cutoff (MWCO) tubular ceramic membrane module. The variables studied were the bioreactor slurry permeation characteristics, such as: the permeate flux, VFA and nutrient removal rates as a function of applied transmembrane pressure, fluid recirculation velocity, suspended matter concentration, and process operating time. Results indicated that the permeate flux, VFA, and nutrients removal rates are directly proportional to the fluid recirculation velocity in the range between 0.6 and 1.0 m/s, applied pressure when these are lower than 1.5 bar, and inversely proportional to the total suspended solids concentration in the range between 23,466 and 34,880 mg/L. At applied pressure higher than 1.5 bar the flux is not more linearly dependent due to concentration polarization and fouling effects over the membrane surface. It was also found that the permeate flux declines rapidly during the first 5-8 h, and then levels off with a diminishing rate of flux decay.

Key words: Waste processing; Biomass production chamber; Volatile fatty acids; Anaerobic bioreactor; Nanofiltration; Permeate flux

Address correspondence to Dr. Guillermo Colón. Tel: (787) 832-4040; Fax: (787) 832-3655; E-mail: gu_colon@rumac.uprm.edu




Life Support & Biosphere Science, Vol. 7, pp. 301-310
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Copyright © 2001 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Electrolytic Removal of Nitrate from Crop Residues

Guillermo Colón1 and John C. Sager2

1University of Puerto Rico, Mayagüez Campus, Chemical Engineering Department, P.O. Box 9046, Mayagüez, PR 00681
2National Aeronautics and Space Administration, Biological Science Branch, Branch Code YA-D3, J.F. Kennedy Space Center, FL 32899

The Controlled Ecological Life Support System (CELSS) resource recovery system, which is a waste-processing system, uses aerobic and anaerobic bioreactors to recover plants nutrients and secondary foods from the inedible biomass. Crop residues contain a significant amount of nitrate. There are actually two major problems concerning nitrate: 1) both CELSS biomass production and resource recovery consume large quantities of nitric acid, and 2) nitrate causes a variety of problems in both aerobic and anaerobic bioreactors. The nitrate anion causes several problems in the resource recovery system in such a way that removal prior to the process is highly desirable. The technique proposed to remove nitrate from potato inedible biomass leachate and to satisfy the nitric acid demand was a four-compartment electrolytic cell. In order to establish the electrolytic cell performance variables, experiments were carried out using potato crop residue aqueous leachate as the diluate solution. The variables studied were the potato biomass leachate composition and electrical properties, preparation of compartment solutions to be compatible with the electrolytic system, limiting current density, nutrients removal rates as a function of current density, fluid hydrodynamic conditions, applied voltage, and process operating time during batch recirculation operation. Results indicated that the limiting current density (maximum operating current density) was directly proportional to the solution electrical conductivity an a power function of the linear fluid velocity in the range between 0.083 and 0.403 m/s. During the electrolytic cell once-through operation, the nitrate, potassium, and other nutrient removal rates were proportional to the current density and were inversely proportional to fluid velocity. The removal of monovalent ions was found to be higher than divalent ones. Under batch recirculation operation at constant applied voltage of 4.5 and 8.5 V, it was found that the nutrient removal rates were independent of applied voltage, but were proportional to the ions concentration and operating time.

Key words: Resource recovery system; Electrolytic removal; Nitrate

Address correspondence to Dr. Guillermo Colón. Tel: (787) 832-4040; Fax: (787) 832-3655; E-mail: gu_colon@rumac.uprm.edu




Life Support & Biosphere Science, Vol. 7, pp. 311-318
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Copyright © 2001 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Effect of Environment on the Free and Peptide Amino Acids in Rice, Wheat, and Soybeans

D. J. Ahn,1 O. Adeola,2 and S. S. Nielsen3

1Dow Chemical Co., Specialty Chemicals, 1691 N. Swede Rd., Midland, MI 48674
2Department of Animal Sciences, Lilly Hall, Purdue University, West Lafayette, IN 47907
3Department of Food Science, Food Science Building, Purdue University, West Lafayette, IN 47907-1160

Controlled environments (CE) in which light, carbon dioxide, and nutrients are regulated are known to affect the chemical composition of plants. Controlled Ecological Life Support System (CELSS) environments are required for a Mars or lunar base where food resupply is both impractical and risky. Astronauts in a CELSS would need to grow and process edible biomass into foods. The complete nature of the changes in chemical composition of CE-grown plants is unknown but must be determined to ensure a safe and nutritionally adequate diet. In this article, we report the changes that occur in free and peptide-bound amino acids (AA) of select CELSS crops (rice, wheat, and soybean) grown in the field or in CE. The nonnitrate nonprotein nitrogen fraction was extracted and then analyzed for free and peptide AA. For grain or seeds, AA levels tended to increase from field to CE conditions; however, for vegetative material, AA levels remained the same or decreased from field to CE conditions. As such compositional changes are identified, researchers will be better able to design safe and nutritious diets for astronauts while minimizing needed energy and other resources.

Key words: Nutrition; Plants; Proteins; Amino acids; Controlled environments

Address correspondence to S. S. Nielsen. Tel: (765) 494-8328; Fax: (765) 494-7953; E-mail: nielsens@foodsci.purdue.edu




Life Support & Biosphere Science, Vol. 7, pp. 319-325
1069-9422/01 $20.00 + .00
Copyright © 2001 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Issues in Life Support and Human Factors in Crew Rescue from the ISS

Kieran Smart

Spacehab, Houston, TX 77058

The design and development of crew emergency response systems, particularly to provide an unplanned emergency return to Earth, requires an understanding of crew performance challenges in space. The combined effects of psychological and physiological adaptation during long-duration missions will have a significant effect on crew performance in the unpredictable and potentially life-threatening conditions of an emergency return to Earth. It is therefore important that the systems to be developed for emergency egress address these challenges through an integrated program to produce optimum productivity and safety in times of utmost stress. Fundamental to the success of the CRV is the Environmental Control and Life Support System (ECLSS), which provides the necessary conditions for the crew to survive their return mission in a shirtsleeve environment. This article will discuss the many issues in the design of an ECLSS system for CRV and place it in the context of the human performance challenges of the mission.

Key words: Crew rescue; Human factors; Environmental Control and Life Support System (ECLSS); Human performance challenges

Address correspondence to Kieran Smart, M.D. Tel: (281) 483-6859; Fax: (281) 483-1847; E-mail: ksmart@ems.jsc.nasa.gov




Life Support & Biosphere Science, Vol. 7, pp. 327-334
1069-9422/01 $20.00 + .00
Copyright © 2001 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Some Influences of the Physical Environment on Human Cognition

Valerie L. Shalin

Department of Psychology, Wright State University, Dayton, OH 45435

The value of human work, even when it is primarily physical, arises from unique cognitive capabilities. This article samples a broadly distributed research base regarding influences of the physical environment on human cognition. The presentation draws primarily on studies conducted within the context of dynamic physical domains of work, to address controls and information sources for enabling human intervention, and related reasoning and planning. Several examples illustrate the role of the environment as a source of information and as an influence on the sequencing of work activity. Life support is discussed both as an instance of a dynamic physical system and for its potential to preclude direct engagement with the environment, with predictable cognitive consequences.

Key words: Human cognition; Physical environment; Work activity; Life support systems

Address correspondence to Valerie L. Shalin. Tel: (937) 775-2023; Fax: (937) 775-3347; E-mail: vshalin@wright.edu