ESA's Potable Water Recycling Concept, System's Architecture and Test Results 941531

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. For the brines and urine processor, a vapour-compression distillation (VCD) concept is considered.

A simplified breadboard of the Core Water-Recycling System was installed, consisting of a microbial stabilisation step (peracetic acid/hydrogen peroxide and a short UV treatment) followed by ultra-filtration and two successive reverse osmosis steps at acidic and neutral pH.

Long-duration testing with this breadboard treating real shower water was performed showing that the resulting water quality fulfilled the drinking water standard except for the total organic carbon content that was slightly above the standard value of 0.5 pmm. The reprocessed water also proved to be safe from a microbiological and toxicological (including pyrogens) point-of-view.