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The development of a spectrophotometric analyzer for use on water samples in microgravity environments is discussed. The instrument is constructed around a commercial spectrophotometer, the Hewlett-Packard HP8453, with a separate turbidimetric analyzer, here a modified Hach 2100P ratio turbidimeter. Flow-through sample cells were constructed for each instrument to support microgravity use and sample deaeration. Spectrophotometric analyses on aqueous samples on orbit are sensitive to the presence of undissolved gases in the samples. In a micro-g environment, free gas in samples can and does remain suspended, clouding the mixture and interfering with spectral optical density measurements. This paper discusses the design of a spectrophotometric analyzer, with particular emphasis on the merits of two approaches to eliminating free gas interferences in on-orbit water analyses: hyperbaric gas redissolution and deaeration across a hydrophobic membrane.

Among the challenges of designing and constructing Space Station Freedom is the development of the water system. A review of past efforts in reclaiming waste water in enclosed environments reveals that there are many gaps in the biomedical understanding of this process. Some of the key uncertainties of human interaction with a closed water system include determining potential contaminants and establishing safe levels of multiple compounds in the enclosed system of Space Station. Another uncertainty is the microbial constituency of such a system and what impact it could have on crew health and performance. The use of iodine as the passive biocide may have both an indirect and direct impact on the crew. In this paper the initial results of the Water Recovery Test are reviewed from a biomedical perspective, revealing areas where more information is needed to develop the ECLSS water system.

A Total Organic Carbon (TOC) Analyzer has been developed for a Life Sciences Risk Mitigation Flight Experiment to be conducted on Spacehab and the Russian space station, Mir. Initial launch is scheduled for December 1996 (flight STS-81). The analyzer will be tested on the Orbiter in the Spacehab module, including when the Orbiter is docked at the Mir space station. The analyzer is scheduled to be launched again in May 1997 (STS-84) when it will be transferred to Mir. During both flights the analyzer will measure the quality of recycled and ground-supplied potable water on the space station. Samples will be archived for later return to the ground, where they will be analyzed for comparison to in-flight results. Water test samples of known composition, brought up with the analyzer, also will be used to test its performance in microgravity. Ground-based analyses of duplicates of those test samples will be conducted concurrently with the in-flight analyses.

The process used to identify, select and design an approach to the isolation and concentration of volatile organic compounds from a water sample prior to chemical analysis in a microgravity environment is described. The Volatile Organics Concentrator (VOC) system described in this paper has been designed for attachment to a gas chromatograph/mass spectrometer (GC/MS) for analysis of volatile organics in water on Space Station. In this work, in order to rank the many identified approaches, the system was broken into three critical areas. These were gases, volatile separation from water and water removal/GC/MS interface. Five options involving different gases (or combinations) for potential use in the VOC and GC/MS system were identified and ranked. Nine options for separation of volatiles from the water phase were identified and ranked. Seven options for use in the water removal/GC column and MS interface were also identified and included in overall considerations.

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.

Two simulated spacecraft water systems are being used to evaluate the effectiveness of iodine for controlling microbial contamination within such systems. An iodine concentration of about 2.0 mg/L is maintained in one system by passing ultrapure water through an iodinated ion exchange resin. Stainless steel coupons with electropolished and mechanically-polished sides are being used to monitor biofilm formation. Results after three years of operation show a single episode of significant bacterial growth in the iodinated system when the iodine level dropped to 1.9 mg/L. This growth was apparently controlled by replacing the iodinated ion exchange resin, thereby increasing the iodine level. The second batch of resin has remained effective in controlling microbial growth down to an iodine level of 1.0 mg/L. Scanning electron microscopy indicates that the iodine has impeded but may have not completely eliminated the formation of biofilm.

The ability of iodine to maintain microbial water quality in a simulated spacecraft water system is being studied. An iodine level of about 2.0 mg/L is maintained by passing ultrapure influent water through an iodinated ion exchange resin. Six liters are withdrawn daily and the chemical and microbial quality of the water is monitored regularly. Stainless steel coupons used to monitor biofilm formation are being analyzed by culture methods, epifluorescence microscopy, and scanning electron microscopy. Results from the first two years of operation show a single episode of high bacterial colony counts in the iodinated system. This growth was apparently controlled by replacing the iodinated ion exchange resin. Scanning electron microscopy indicates that the iodine has limited but not completely eliminated the formation of biofilm during the first two years of operation.

When construction of Space Station Freedom reaches the Permanent Manned Capability stage, plans call for the Water Recovery and Management Subsystem to treat distilled urine, spent hygiene water, and humidity condensate in order to reclaim water of potable quality. The reclamation technologies currently baselined to process these wastewaters include adsorption, ion exchange, catalytic oxidation, and disinfection. To ensure that baselined technologies will be able to effectively remove those compounds that present health risks to the crew, the National Research Council has recommended that additional information be gathered on specific contaminants in wastewaters representative of those to be encountered on Space Station. This paper reports the efforts by the Water and Food Analytical Laboratory at the Johnson Space Center to enlarge the database of potential contaminants in humidity condensate.

The primary source of potable water planned for the International Space Station will be generated from the reclamation of humidity condensate, urine, and hygiene waters. It is vital to crew health and performance that this reclaimed water be safe for human consumption, and that health risks associated with recycled water consumption be identified and quantified. Only recently has data been available on the chemical constituents in reclaimed waters generated in microgravity. Results for samples collected during Mir-21 reveal that both the reclaimed water and stored water are of potable quality, although the samples did not meet U.S. standards for total organic carbon (TOC), total phenols, and turbidity.

Twenty-nine recycled water, eight stored (ground-supplied) water, and twenty-eight humidity condensate samples were collected on board the Mir Space Station during the Phase One Program (1995-1998). These samples were analyzed to determine potability of the recycled and ground-supplied water, to support the development of water quality monitoring procedures and standards, and to assist in the development of water reclamation hardware. This paper describes and summarizes the results of these analyses and lists the lessons learned from this project. Results show that the recycled water and stored water on board Mir, in general, met NASA, Russian Space Agency (RSA), and U.S. Environmental Protection Agency (EPA) standards.

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.

Potable- and hygiene-quality water will be supplied to crews on the International Space Station through the recovery and purification of spacecraft wastewaters, including humidity condensate, urine, and wash water. Contaminants released into the cabin air from human metabolism, hardware offgassing, flight experiments, and routine operations will be present in spacecraft humidity condensate; normal constituents of urine and bathing water will be present in urine and untreated wash water. This report describes results from detailed analyses of Mir reclaimed potable water, ground-supplied water, and humidity condensate. These results are being used to develop and test water recycling and monitoring systems for the International Space Station (ISS); to evaluate the efficiency of the Mir water processors; and to determine the potability of the recycled water on board.

Iodine depletion in a simulated water storage tank and distribution system was examined to support a larger research program aimed at developing disinfection methods for spacecraft potable water systems. The main objective of this study was to determine the rate of iodine depletion with respect to the surface area of the stainless steel components contacting iodinated water. Two model configurations were tested. The first, representing a storage and distribution system, consisted of a stainless steel bellows tank, a coil of stainless steel tubing and valves to isolate the components. The second represented segments of a water distribution system and consisted of eight individual lengths of 21-6-9 stainless tubing similar to that used in the Shuttle Orbiter. The tubing has a relatively high and constant surface area to volume ratio (S/V) and the bellows tank a lower and variable S/V.

The ability to aseptically remove samples and products, and the capability for addition of materials to sterile or otherwise microbially susceptible systems have always been compromised by the lack of a reliable means of sterilizing the mating fixtures. Cultures of mammalian cells are particularly vulnerable to microbial contamination due to the complexity of nutrient media and the lengthy periods required for cell growth. The Microwave Sterilizable Access Port has been developed to overcome this limitation. The system consists of three primary components: a microwave power source, a combined sterilization chamber/in-line valve port assembly, and a specimen transfer interface. Microwave energy is transmitted via coaxial cable to a small pressurized chamber that serves as a sterile transition between the surrounding environment and the system during transfer of materials.

Iodine is a flight-proven disinfectant which because of its unique properties, will probably be used on the Space Station and future manned spaceflight applications. However, present knowledge of and experience with iodination is insufficient to assess crew safety when used in conjunction with reclamation or recycle systems, especially if the reclaimed water is consumed.

Disinfection of water and wastewater was proven to be feasible using a Breadboard Electrochemical Ozone Generator (EOG). A static gas/liquid separator, containing a microporous, hydrophobic membrane, was tested with the Breadboard EOG, and was found to increase the concentration of the ozone (O3) dissolved in the water. Distilled water and selected wastewaters were disinfected, achieving dissolved O3 concentrations up to 3 mg/L. The hardware is capable of operating in 0-g and 1-g environments. An end-item Electrochemical Ozonator (EO), sized to disinfect 116 kg of potable water per day, was projected to weigh 1.2 kg and consume only 18.5 W.

On the International Space Station (ISS), humidity condensate will be collected from the atmosphere and treated by multifiltration to produce potable water for use by the crews. Ground-based development tests have demonstrated that multifiltration beds filled with a series of ion-exchange resins and activated carbons can remove many inorganic and organic contaminants effectively from wastewaters. As a precursor to the use of this technology on the ISS, a demonstration of multifiltration treatment under microgravity conditions was undertaken. On the Space Shuttle, humidity condensate from cabin air is recovered in the atmosphere revitalization system, then stored and periodically vented to space vacuum. A Shuttle Condensate Adsorption Device (SCAD) containing sorbent materials similar to those planned for use on the ISS was developed and flown on STS-68 as a continuation of DSO 317, which was flown initially on STS-45 and STS-47.

The objective of this study was to investigate combining GC/MS and CE methods to allow sub-mg/L levels of organic acids to be determined in various water samples. This study also served as a basis for evaluating these instruments for in-flight spacecraft water-quality monitoring and to help determine the modifications needed to convert terrestrial hardware for use in microgravity environments. This paper reports on current GC/MS and CE method development and data generated from some recent spacecraft-related water samples. Plans for further method development are also discussed.

Archival sampling of potable water and condensate for ground laboratory analysis has been an important part of the Shuttle-Mir program because of coolant leaks and other events on Mir that have affected water quality. We report here the development of and preliminary results from a novel device for single phase humidity condensate collection at system pressures. The sampler consists of a commercial-off-the-shelf Teflon® bladder and a custom reinforced Nomex® restraint that is sized properly to absorb the stress of applied pressures. A plastic Luer-Lock disconnect, with poppet actuated by a mating Luer-Lock fitting, prevents the contents from being spilled during transport. In principle, a sampler of any volume can be designed. The empty mass of the reusable one-liter sampler is only 63 grams. Several designs were pressure tested and found to withstand more than 3 atmospheres well in excess of typical spacecraft water or wastewater system pressures.

The STS water system is treated with iodinated water in order to prevent microbial contamination. This water is prepared by adding a concentrated solution of iodine to Ground Service Equipment (GSE) before adding the water in that unit to the spacecraft system. The solution is prepared by dissolving iodine in ethanol to make a tincture stock solution. While this procedure is rapid, the ethanol increases the carbon levels in the STS potable water and may produce unpleasant odors. The resulting high carbon levels preclude the use of total organic carbon measurements as a water quality monitoring tool. The use of triiodide solutions was studied as a substitute for using ethanol solutions. Two dissolution agents, sodium iodide and hydriodic acid, were investigated. Sodium iodide was studied at molar concentration ratios ranging from 1:1 to 2.5:1 sodium iodide to molecular iodine.