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This paper addresses the derivation of chemical ersatz recipes for use in the evaluation of development hardware designed for advanced spacecraft water recovery systems. The recipes simulate characteristics of wastewater generated on a transit mission and on an early planetary base (EPB). In addition, recipes are provided which simulate the water quality of the early planetary base wastewater as it moves through a combination biological and physical-chemical water recovery system. These ersatz are considered to be accurate representations of the wastewater as it passes through primary, secondary, and tertiary processing stages. The EPB ersatz formulas are based on chemical analyses of an integrated water recovery system performance test that was conducted over a period of one year. The major inorganic and organic chemical impurities in the raw wastewater, and in the effluent from the various subsystems, were identified and quantified.

The work presented in this paper summarizes the performance of subsystems used during an integrated advanced water recovery system test conducted by the Crew and Thermal Systems Division (CTSD) at NASA-Johnson Space Center (JSC). The overall objective of this test was to demonstrate the capability of an integrated advanced water recovery system to produce potable quality water for at least six months. Each subsystem was designed for operation in microgravity. The primary treatment system consisted of a biological system for organic carbon and ammonia removal. Dissolved solids were removed by reverse osmosis and air evaporation systems. Finally, ion exchange technology in combination with photolysis or photocatalysis was used for polishing of the effluent water stream. The wastewater stream consisted of urine and urine flush water, hygiene wastewater and a simulated humidity condensate.

The work presented in this paper summarizes the early results of an integrated advanced water recovery system test conducted by the Crew and Thermal Systems Division (CTSD) at NASA-Johnson Space Center (JSC). The system design and the results of the first two months of operation are presented. The overall objective of this test is to demonstrate the capability of an integrated advanced water recovery system to produce potable quality water for at least six months. Each subsystem is designed for operation in microgravity. The primary treatment system consists of a biological system for organic carbon and ammonia removal. Dissolved solids are removed by reverse osmosis and air evaporation systems. Finally, ion exchange technology in combination with photolysis or photocatalysis is used for polishing of the effluent water stream. The wastewater stream consists of urine and urine flush water, hygiene wastewater and a simulated humidity condensate.

An advanced water recovery system requires the development of a minimum-consumable post-processor system to produce potable water that meets NASA requirements. Residual organic impurities and ammonium, nitrite, and nitrate ions are the principal challenges to the system. Ion exchange resins and organic removal materials that elute minimum organics were investigated. UP604 (Rohm & Haas) and NRW36/36SC (Purolite) ion exchange resins were shown to have comparable removal capacities of 1.29-1.78 meq/mL of bed volume. The organic removal materials exhibited poor removal capacities of less than 0.5 mg/mL of bed volume. Two ultraviolet photo-oxidative processes were investigated to reduce the need for expendable organic removal materials. A photolytic and a photocatalytic process both demonstrated the ability to reduce organic impurities to less than 500 μg/L. A description of these tests and results are discussed and presented in detail in this paper.

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.

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.

Long duration missions in space will require regenerative processes to recover water for crew reuse. Membrane processes are attractive as a primary processor in water recovery systems (WRS) because of their design simplicity, low specific energy requirements, small size, and high water recovery. However, fouling has historically been regarded as a disadvantage of membrane-based processes. This fouling is often caused by micelle buildup on the membrane surface by high-molecular-weight organics (e.g., from soaps and laundry detergents). This paper describes a two-stage fouling-resistant ultrafiltration (UF)/reverse osmosis (RO) prototype subsystem, which was designed and constructed for a WRS in the Life Support Systems Integration Facility (LSSIF) at NASA Johnson Space Center (NASA/JSC). The first stage of the subsystem is a tube-side-feed hollow-fiber UF module that removes contaminants that tend to foul spiral-wound modules.

An aqueous phase catalytic oxidation system (APCOS) was designed, tested and delivered to NASA/Johnson Space Center (JSC). The APCOS removes residual organic impurities in reclaimed water to a level acceptable for potable use and to provide disinfection. The reactor, which contains a heterogeneous catalyst consisting of a noble metal on an inert support medium, operates at 120 - 150 °C and at fluid pressures of several atmospheres to maintain an aqueous liquid phase. Pressurized gaseous oxygen, used as the oxidant, is directly injected into the liquid phase. A description of the subsystems process hardware is presented. The APCOS was demonstrated to mineralize organic impurities at concentrations of 100 mg/L total organic carbon (TOC) to < .5 mg/L (<500 μg/L TOC). In addition, disinfection features were demonstrated with microbial challenge tests.

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.

Long duration manned space missions will require integrated biological and physicochemical processes for recovery of resources from wastes. This paper discusses a hybrid regenerative biological and physicochemical water recovery system designed and built at NASA's Crew and Thermal Systems Division (CTSD) at Johnson Space Center (JSC). The system is sized for a four-person crew and consists of a two-stage, aerobic, trickling filter bioreactor; a reverse osmosis system; and a photocatalytic oxidation system. The system was designed to accommodate high organic and inorganic loadings and a low hydraulic loading. The bioreactor was designed to oxidize organics to carbon dioxide and water; the reverse osmosis system reduces inorganic content to potable quality; and the photocatalytic oxidation unit removes residual organic impurities (part per million range) and provides in-situ disinfection. The design and performance of the hybrid system for producing potable/hygiene water is described.

The purification of reclaimed water is essential to water reclamation technology life-support systems in lunar/Mars habitats. Lynntech, Inc., working with NASA-JSC, is developing an electrochemical UV reactor which generates oxidants, operates at low temperatures and requires no chemical expendables. The reactor is the basis for an advanced oxidation process, in which electrochemically generated ozone and hydrogen peroxide are used, in combination with ultraviolet light irradiation, to produce hydroxyl radicals. Results from this process are presented which demonstrate concept feasibility for removal of organic impurities and disinfection of water for potable and hygiene reuse. Power, size requirements, Faradaic efficiency and process reaction kinetics are discussed. At the completion of this development effort, the reactor system will be installed in JSC's regenerative water recovery test facility for evaluation to compare this technique with other candidate processes.

NASA's future manned missions to explore the Solar system are by nature of long duration, mandating extensive regeneration of life support consumables from wastes generated in space-based habitats. Long duration exploration missions would otherwise be prohibitive due to the number and frequency of energy-intensive resupply missions from Earth. Resource recovery is therefore a critical component of the controlled ecological life support system (CELSS). In order to assess resource recovery technologies for CELSS applications, the Crew and Thermal Systems Division at NASA-Johnson Space Center convened a three-day workshop to assess potential resource recovery technologies for application in a space-based CELSS. Ninety experts from government, industry and academia attended the workshop. This paper describes the methodology of assessing and ranking of these technologies. Recommendations and issues are identified.

A single cell electrochemical reactor that utilizes a proton exchange membrane (PEM) as a solid electrolyte is being investigated and developed at Texas A&M University for post-treatment of reclaimed waters with low or negligible electrolyte content. Post-treatment is a final polishing of reclaimed waste waters prior to reuse and constitutes removing organic impurities at levels as high as 100 ppm to <500 ppb total organic carbon (TOC) content and provides disinfection. The system does not utilize or produce either expendable hardware components or chemicals and has no moving parts. This paper discusses a single cell reactor concept; test system design; the role of the proton exchange membrane; and the principle of organic impurity oxidation at PEM interfacial reaction zones. The fabrication performance evaluation; design and sizing of a prototype system are discussed. Test data and kinetic analysis are presented.

Electrooxidation is a means of removing organic solutes directly from waste waters without the use of chemical expendables. Research sponsored by NASA Johnson Space Center is currently being pursued at Texas A&M University to demonstrate the feasibility of the concept for oxidation of organic impurities common to urine, shower waters and space habitat humidity condensates. Electrooxidation of urine and waste water ersatz was experimentally demonstrated. This paper discusses the electrooxidation principle, reaction kinetics, efficiency, power, size, experimental test results and water reclamation applications. Process operating potentials and the use of anodic oxidation potentials that are sufficiently low to avoid oxygen formation and chloride oxidation are described. The design of a novel electrochemical system that incorporates a membrane-based electrolyte based on parametric test data and current fuel cell technology is presented.

A microgravity whole body shower and waste water recovery system were evaluated in three separate closed loop tests at NASA/JSC. These tests covered a period from August 1985 to June 1987 in which shower waste water was reclaimed and reused for showering. Test persons showered in a preprototype whole body shower following a protocol similar to that anticipated for the Space Station. Each test was performed by using different water recovery system technologies which included phase change distillation and two separate reverse osmosis processes. These were integrated with post-treatment for the final purification of the reclaimed water. The phase change, a preprototype Thermoelectric Hollow Fiber Membrane Evaporation Subsystem was used for the initial test with chemical pretreatment of the shower waste water input. A reverse osmosis dynamic membrane system was used for the second test and a 2-stage ultrafiltration/reverse osmosis system for the third test.

An ultraviolet driven photocatalytic post-treatment technique for the purification of waste water distillates, reverse osmosis permeates and spacecraft habitat atmospheric humidity condensates is described. Experimental results show that organic impurity carbon content of simulated reclamation waters at nominal 40 PPM level are reduced to, PPB using a recirculating batch reactor. The organic impurities common to reclaimed waste waters are completely oxidized employing minimum expendables (stoichiometric oxygen). This paper discusses test results and parametric data obtained for design and fabrication of a breadboard system. The parametric testing includes UV light source evaluation, photolysis vs photocatalysis comparison, oxygen concentration dependence, temperature dependence, reactor mixing, disinfection features, photocatalyst loading, photocatalyst degradation studies and power consumption estimates.

The development of solid oxide electrolysis cell technology has progressed to a level that allows for construction of a three-person breadboard system. This paper addresses the design, fabrication, and testing of the breadboard, and the data base obtained for future electrolysis systems that have application for planetary manned missions and habitats. The breadboard contains sixteen tubular cells in a closely packed bundle for the electrolysis of carbon dioxide and water vapor. Palladium diffusion tubes are arranged in the bundle parallel and symmetrical with the electrolyzer tubes for removal and separation of hydrogen from the process gases. Basic information on energy requirements, volume, and weight, are described. The operational characteristics related to measurement of the reactant and product gas compositions, temperature distribution along the electrolyzer tubular cells and through the bundle, and thermal energy losses are assessed.

This paper discusses the recent developments in water quality monitoring for Space Station reclaimed wastewaters. A preprototype unit that contains an ultraviolet absorbance organic carbon monitor integrated with pH and conductivity sensors is presented. The preprototype has provisions for automated operation and is a reagentless flow-through system without any gas/liquid interfaces. The organic carbon monitor detects by ultraviolet absorbance the organic impurities in reclaimed wastewater which may be correlated to the organic carbon content of the water. A comparison of the preprototype organic carbon detection values with actual total organic carbon measurements is presented. The electrolyte double junction concept for the pH sensor and fixed electrodes for both the pH and conductivity sensors are discussed. In addition, the development of a reagentless organic carbon analyzer that incorporates ultraviolet oxidation and infrared detection is presented.

A shower test was conducted recently at NASA-JSC in which waste water was reclaimed and reused. Test subjects showered in a prototype whole body shower following a protocol similar to that anticipated for Space Station. The waste water was purified using reverse osmosis followed by filtration through activated carbon and ion exchange resin beds. The reclaimed waste water was maintained free of microorganisms by using both heat and iodine. This paper discusses the test results, including the limited effectiveness of using iodine as a disinfectant and the evaluation of a Space Station candidate soap for showering. In addition, results are presented on chemical and microbial impurity content of water samples obtained from various locations in the water recovery process.

A microgravity whole body shower (WBS) and a waste water recovery system (WWRS) were used in a closed loop test at the Johnson Space Center. The WWRS process involved chemical pretreatment, phase change distillation and post-treatment. A preprototype Thermoelectric Integrated Hollow Fiber Membrane Evaporation Subsystem (TIMES) was used for distillation after pretreatment and the post-treatment was accomplished with activated carbon, mixed ion exchange resin beds and microbial check valve (MCV) iodine bactericide dispensing units. The purposes of this test were to evaluate a NASA approved Shuttle soap for whole body showering comfort; evaluate the effects of the shower water on the WBS and the TIMES; and evaluate purification qualities of the recovered water in a closed loop operation.