The Path to Recovering a Metric Ton of Water from Urine-Brine with the Brine Processor Assembly

The Brine Processor Assembly (BPA), developed by Paragon Space Development Corporation as a one-year Technology Demonstration, has now been in operation onboard the International Space Station (ISS) for almost four years. BPA recovers available water from urine-brine produced by the ISS Urine Processor Assembly (UPA) via forced convection of cabin air coupled with a patented membrane distillation process. A dual-layer ionomer and microporous membrane bladder retains the liquid brine while water vapor pervaporates into the cabin, for collection as humidity condensate. In the last year BPA operations have been streamlined to better align with UPA processing cycles. With the majority of science objectives met and ISS integration milestones achieved, the BPA has slowly transitioned from a technology demonstration to a regularly operating piece of the ISS Water Recovery and Management (WRM) architecture. As of February 2025, 60 full operational runs have been completed spanning 864 days of active operations, recovering an estimated 1087 kg (L) (over a metric ton!) of water from urine-brine. This represents a cost savings of roughly $81 million from the mass of water and supporting equipment that has not needed to be launched to or discarded from the ISS, minus the cost of consumables (bladders and odor filters). This paper presents a review and discussion on BPA’s development, on-orbit performance, and cumulative metrics now that a substantial flight dataset is available, the technology demonstration period has ended, and new performance milestones have been met.