Search Results

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.

A study on Hygiene in long duration space missions was held between 1988-1989 for ESA Long Term Programme Office (1), (2). The impact of Hygiene on station contamination and station layout was reviewed as well as psychological, social and cultural aspects, leading to the conclusion that hygiene is a key habitability issue. Among its main results, the study highlighted the importance of water in both environmental and personal hygiene: the use of water in body hygiene is culturally and socially established. As a consequence, water was found as the main consumable in hygiene functions. Thus, due to the limited water availability in space stations, particular attention was paid to on board water management. Simulation software was developed to demonstrate the relation between hygiene subsystems concepts and water requirements. The software was designed as a tool. Parameters allow to define various mission profiles.