Direct Osmotic Concentration: A Primary Water Treatment Process for Space Life Support Applications

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. Information is also presented such that life support architecture designers and modelers can accurately consider DOC along side other processes for primary water treatment and recycle based on the data developed to date.

From the preliminary results, DOC systems should be capable of recovering (as potable water) greater than 97 % of all hygiene, urine, and condensate water collected in a space habitat. DOC is capable of this with no resupply and low energy cost and should be considered carefully in future space life support system architecture and modeling studies.