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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.

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.

Direct osmotic concentration (DOC) has been identified as a potential technology for recycling of wastewater to drinking water in advanced life support (ALS) systems. As a result the DOC process has been selected for a NASA Rapid Technology Development Team (RTDT) effort. The current project focuses on advancing the development of this technology to a level appropriate for human rated testing. A new prototype of a DOC system is been designed and fabricated that addresses the deficiencies encountered during the testing of the original system and able to achieve a long-term and reliable operation. Background information is provided about the technologies investigated and their capabilities, results from preliminary tests, and the milestones plan and activities for the RTDT program intended to develop a second generation prototype of the DOC system.