Search Results

Magnetically Assisted Gasification (MAG) is a relatively new concept for the destruction of solid wastes aboard spacecraft, lunar and planetary habitations. Three sequential steps are used to convert the organic constituents of waste materials into useful gases: filtration, gasification, and ash removal. In the filtration step, an aqueous suspension of comminuted waste is separated and concentrated using a magnetically consolidated depth filter composed of granular ferromagnetic media. Once the filter is fully loaded, the entrapped solids are thermochemically gasified via a variety of mechanisms including pyrolysis, isomerization, and oxidation reactions. Finally, the inorganic ash residue is removed from the magnetic media by fluidization and trapped downstream by filtration. Importantly, for each of these steps, the degree of consolidation or fluidization of the granular ferromagnetic media is controlled using magnetic forces.

A breadboard Electrochemical Water Recovery System (EWRS) that is designed to produce potable water from a composite waste stream without the use of expendables is described in this paper. Umpqua Research Company working together with NASA/JSC developed a sequential three-step process to accomplish this task. Electrolysis removes approximately 60% of the organic contaminants from ersatz composite waste water containing a total organic carbon (TOC) concentration of 707 mg/L. The contaminants in this solution consist of organic and inorganic impurities common to laundry, shower, handwash, and urine waste water. Useful gases and organic acids are the chief by-products of the first step. The partially oxidized electrolysis solution is then transferred to the electrodialysis process where ionized organic and inorganic species are concentrated into a brine. The deionized solution of recovered water contains ∼6% of the original organic contaminants and >90% of the original water.

The Microbial Check Valve (MCV) is a reloadable flow-through canister containing iodinated ion exchange resin, which is used aboard the Shuttle Orbiter as a disinfectant to maintain water potability. The MCV exhibits a significant contact kill and imparts a biocidal residual I2 concentration to the effluent. MCVs in current use have nominal 30 day lives. MCVs baselined for Space Station Freedom will have 90 day lives, and will require replacement 120 times over 30 years. Means to extend MCV life are desirable to minimize resupply penalties. New technology has been developed for fully autonomous in situ regeneration of an expended MCV canister. The Regenerative Microbial Check Valve (RMCV) consists of an MCV, a packed bed of crystalline I2, a flow diverter valve, an in-line iodine monitor and a microcontroller. During regeneration, flow is directed first through the packed I2 bed and then into the MCV where the resin is replenished.

A significant decline in molecular iodine concentration is associated with the iodination of heavily contaminant-laden process water streams such as humidity condensate and urine distillate. Iodine loss is attributable to the reaction of this biocide with organic constituents. This phenomenon has been investigated using time resolved molecular absorption spectrophotometry of iodinated ersatz humidity condensates and iodinated ersatz urine distillates across the ultraviolet and visible spectral regions. Rates of iodine loss have also been studied using single contaminant systems at equivalent concentrations. The predominant reactive species have been identified as thiourea and formic acid. Pseudo-first order rate constants have been determined for ersatz contaminant model mixtures and for individual reactive constituents. Second order rate constants have been determined for the bimolecular reaction of iodine and formic acid.

The electrosynthesis of expendable reagents including acids, bases, and oxidants from simple salts or salt mixtures has been demonstrated using a variety of electrochemical cells. A five chambered electrodialytic water splitting (EDWS) cell with bipolar membranes was utilized to efficiently convert sodium sulfate, sodium chloride, potassium nitrate, and potassium chloride to conjugate acids and bases. With the same cell, selective segregation of cations and anions from mixed salt solutions occurred, resulting in relatively pure acids and bases. These results suggest that pure acids and bases can be produced from composite spacecraft brines. Chemical oxidants such as sodium and ammonium persulfate were also synthesized with high current efficiencies by the electrooxidation of salts and acids in a two chambered electrochemical cell.