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Given the constraints of the current launchers, manned exploration beyond LEO implies long time missions, a high mass of metabolic consumables and consequently regenerative life support technologies developments. To validate their efficiency, as well as their reliability, these technologies need to be tested in the most analog conditions (i.e. isolation, limited spare part, …). A large number of these conditions are met in the new permanent French-Italian settlement called Concordia, currently being built in the Antarctic continent. Over the last 15 years, ESA developed regenerative life support technologies. Two of these technologies: a Grey Water Treatment Unit and a Black Water Treatment Unit are currently assembled at the size of 15 to 70 persons to fulfill the Concordia crew needs The first technology is a multi step filtration system and will recycle the shower, washing machine, dish washer and cleaning water.

In the absence of recycling, water represents over 90% of the life-support consumables for a human spacecraft. In addition, over 90% of the waste water generated can be classified as either moderately or slightly contaminated (e.g. shower water, condensate from the air-conditioning system, etc..) The ability to recover potable water from moderately contaminated waste water hence enables significant savings to be made in resupply costs. A development model of such a water-recovery system, based on membrane technology, has been produced and tested using ‘real waste water’ based on used shower water. Results indicate some 95% recovery of potable water meeting European Space Agency (ESA) standards, with total elimination of microbial contaminants such as bacteria, spores and viruses. A second phase focused on improving the functioning of the breadboard and to test it in a long duration test (5-6 months).

Preliminary development of a core water-recycling system for potable water reprocessing has been performed, supported by a critical assessment of the required architecture and extensive experimental testing of materials, technologies and procedures. The functional architecture of the water-recycling system is characterised by a Core Water-Recycling System (CWRS) reprocessing potable water from moderately contaminated water such as hygiene water and condensation and CO2-reduction waters, and a complementary treatment technology allowing further processing of highly contaminated sources such as urine and brines from the core system. The quality of this last processed water is sufficient to allow its reprocessing by the core system. Technologies involved in the core water-recycling system and complementary brine recycling system are based on chemical treatment, ultra-filtration, reverse osmosis at acidic and neutral pH, photo-oxidation and phase-change.

Based on a preliminary study (ref 1) which identified a basic core technology system, essentially based on membrane technologies, capable of providing recovery of water from moderately contaminated waste waters like hygiene water and condensation water, a development work was initiated. Results from this development work are presented. The study covers the detailed design of a breadboard of a core system consisting of 3 successive membrane units : Ultrafiltration on mineral membrane, reverse osmosis and electrodialysis, plus an oxidation step. An alternative configuration including a Nanofiltration step is also considered with the aim of decreasing the operating pressure as compared to reverse osmosis. Experimental testing for the selection of individual components and for the definition of operating procedures have been performed. Feasibility demonstration tests on the complete core configuration are being performed using real shower water and condensation water from a cold room.

Electrodialysis (ED) is an electrically driven process that operates at ambiant temperature and pressure. It is of interest for removing ionized molecules, and reconcentrating them, specially at medium and low concentration. It is always used in association with other membrane technologies and/or pretreatment. It is of high interest to simulate the contact of ED membranes with candidate stabilizing or cleaning agents in a water recycling system. We selected among a large and representative range of commercial anionic and cationic membranes, 20 different ED membranes and tested them regarding their resistance to 5 chemical agents. The samples were immerged in the solution (480 h / 60 °C), and a physical characterisation was performed: dimensional stability, measure of electrical resistance, determination of exchange capabilities. Four membranes presented acceptable performances after contact with hydrogen peroxyde (300 ppm) regarding electrical resistance.