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Direct osmotic concentration (DOC) is a membrane treatment process for reclamation of space craft wastewater. It incorporates a novel system architecture that includes a forward osmosis (FO) and reverse osmosis (RO) subsystem for hygiene (gray) water, and a membrane distillation subsystem for the treatment of urine and humidity condensate. The products of these subsystems are combined and then post-treated by a catalytic oxidation subsystem. This paper documents progress made during the second year of a three year Rapid Technology Development Team (RTDT) effort.

This research is intended to provide contamination and ecosynthesis researchers with an engineering development tool for understanding the productivity of metabolically active low temperature brine habitats as potential sites for bacterial colonization by forward contaminating Earth organisms. The specific extremophile microbial culturing conditions targeted were psychrophilic (low temperature), halophilic (high salt), high ambient sulfur, and anaerobic. These low temperature or freezing point suppressed brine habitats with high ambient sulfur concentrations have been suggested as potential subsurface water resources on both Mars and Europa, and may be common among potentially viable extant water environments in the outer solar system.

For wastewater treatment applications, membrane processes are known to provide excellent treatment but are subject to failure due to membrane fouling. The Direct Osmotic Concentration (DOC) system evaluated in this study provides a membrane based primary treatment process capable of overcoming this problem. A full scale test apparatus containing full scale test module membrane cells has been developed and has undergone preliminary testing that provides a basis for comparison with other primary water recycle process concepts. This study confirms and extends the initial testing of this hardware and determines the required improvements to the existing test mo dules. These improvements, in addition to future testing, are intended to complete the validation of the concept and mature the hardware to the point that human rated test equipment design and development can be based directly on the test module derived data.

Direct osmotic concentration (DOC) has been identified as a potential wastewater treatment process for potable reuse in advanced life support systems (ALSS). As a result, further development of the DOC process is being supported by a NASA Rapid Technology Development Team (RTDT) program. DOC is an integrated membrane system combining three unique membrane separation processes including forward osmosis (FO), membrane distillation (MD), and reverse osmosis (RO) that is designed to treat separate wastewater streams comprising hygiene wastewater, humidity condensate, and urine. An aqueous phase catalytic oxidation (APCO) process is incorporated as post treatment for the product water. In an ongoing effort to improve the DOC process and make it fully autonomous, further development of the three membrane technologies is being pursued.

This study introduces new concepts in the function and placement of membrane based water treatment processes in Exploration Life Support (ELS) System design. These differences are in both form and function and have the potential to radically alter the current paradigms of thought within the ELS research community with regards to the limitations of conventional membrane water treatment. More importantly, they have the potential to change the placement of water processing by quite literally moving it “out of the box”, or in the case of ELS, the standard rack volume. Two possible systems, extremely small scale personal urine treatment and recycle (CEV Lightweight Contingency Water Treatment) and a similar but scaled up habitat wall embedded membrane water treatment pouch, are used to demonstrate the concepts involved.

One of the primary driving forces for space exploration in the foreseeable future is astrobiology, and specifically the search for a plausible sign of life beyond Earth. Because of the size of the potential saltwater ocean involved, Europa is potentially the most interesting, and possibly the only, currently viable (for life) environment in the solar system. It also presents the possibility of remote sensing evaluation for presence or absence of biotic and/or pre-biotic organic material. The material of interest is the non-ice (referring to water ice) surface material near features that have the potential of being in recent communication with the postulated ocean below. An analysis of this material using a full range of inorganic, pre-biotic organic, and metabolically relevant biologic materials as spectrum calibrating target materials, examined under Europan surface conditions, is a daunting proposition. A comprehensive attempt is still pending.

The Lightweight Contingency Water Recovery System (LWC-WRS) harvests water from various sources in or around the Orion spacecraft in order to provide contingency water at a substantial mass savings when compared to stored emergency water supplies. The system uses activated carbon treatment (for urine) followed by forward osmosis (FO). The LWC-WRS recovers water from a variety of contaminated sources by directly processing it into a fortified (electrolyte and caloric) drink. Primary target water sources are urine, seawater, and other on board vehicle waters (often referred to as technical waters). The product drink provides hydration, electrolytes, and caloric requirements for crew consumption. The system hardware consists of a urine collection device containing an activated carbon matrix (Stage 1) and an FO membrane treatment element (or bag) which contains an internally mounted cellulose triacetate membrane (Stage 2).