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Technical Paper

Magnetically Assisted Gasification of Solid Wastes: Comparison of Reaction Strategies

2005-07-11
2005-01-3081
Gradient magnetically assisted fluidized bed (G-MAFB) methods are under development for the decomposition of solid waste materials in microgravity and hypogravity environments. The G-MAFB has been demonstrated in both laboratory and microgravity flight experiments. In this paper we summarize the results of gasification reactions conducted under a variety of conditions, including: combustion, pyrolysis (thermal decomposition), and steam reforming with and without oxygen addition. Wheat straw, representing a typical inedible plant biomass fraction, was chosen for this study because it is significantly more difficult to gasify than many other typical forms of solid waste such as food scraps, feces, and paper. In these experiments, major gasification products were quantified, including: ash, char, tar, carbon monoxide, carbon dioxide, methane, oxygen, and hydrogen.
Technical Paper

Aqueous Phase Ammonia Removal and Destruction System (APARDS)

1997-07-01
972425
In order to meet NASA potable water standards using biological processing, additional purification is needed. Elimination of ammonia species is a significant post-treatment step to achieve this goal. New technology, combining membrane transport and electro-oxidation of ammonia, was developed to solve this problem without the use of expendables. The Aqueous Phase Ammonia Removal and Destruction System (APARDS) Phase I Program rigorously demonstrated the feasibility of each sub-process, and an integrated system was developed that removed and destroyed ammonia from a simulated bioreactor effluent. Membranes and process conditions suitable for ammonia removal have been determined. An Ammonia Removal Module (ARM) was designed for the efficient transfer of ammonia to a secondary electro-oxidation stream where the ammonia was destroyed. The electrolysis cell's electrodes, operational voltage, and flow characteristics were optimized to rapidly destroy ammonia.
Technical Paper

Chemiluminescent Ethanol Biosensor Development

1995-07-01
951686
The investigation and development of a chemiluminescence based ethanol detection concept into a biosensor system is described. The biosensor uses alcohol oxidase to catalyze the reaction of short chain primary alcohols with elemental oxygen to produce hydrogen peroxide and the corresponding aldehyde. The reaction of hydrogen peroxide with an organic luminophore in the presence of a sufficient electric field results in emission of blue light with peak intensity at 425nm. The chemiluminescent light intensity is directly proportional to the alcohol concentration of the sample. The aqueous phase chemistry required for sensor operation is implemented using solid phase modules which adjust the pH of the influent stream, catalyze the oxidation of alcohol, provide the controlled addition of the luminophore to the flowing aqueous stream, and minimize the requirement for expendables. Precise control of the pH has proven essential for the long-term sustained release of the luminophore.
Technical Paper

In Situ Hydrogen Peroxide Generation for Use as a Disinfectant and as an Oxidant for Water Recovery by Aqueous Phase Catalytic Oxidation

1996-07-01
961521
The initial development effort is described for an electrochemical hydrogen peroxide generator and pervaporation module capable of producing and delivering hydrogen peroxide to a contaminated waste water stream as an oxidant or to a pure water stream for use as a disinfectant. A three chambered cell is used to generate hydrogen peroxide by a combined electrodialysis and electrochemical process. Each chamber is separated from its neighbor by a membrane allowing selective production of peroxide anions and hydrogen ions under controlled pH conditions followed by migration to form hydrogen peroxide. Concentrations greater than 6,500mg/L have been produced in this manner. The effects of voltage, pH, membranes, electrode materials, and method of oxygen introduction are delineated. Hydrogen peroxide is then transferred to the end-use stream by pervaporation. The impact of pH, relative flow rates, and ionic strength of sink and source solutions on pervaporation rates is detailed.
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