Advances in the Development of the WRU - An Integrated System to Recover Potable Water from Urine and Condensate"

The Water Recovery Unit (WRU) is based on an open loop triple circulation system with two-stage filtration. The first stage, based on forward osmosis (FO), separating water from the contaminated urine/condensate mix by a draw solution is followed by a second stage of direct contact membrane distillation (DCMD) that separates the clean water from the draw solution and thus provides the FO system with the reconstituted working solution and clean product water for consumption. The latest update presented at ICES 2023 addressed challenges in MD flux and membrane and draw lifetime. This work was part of a de-risk project sponsored by ESA and was brought to conclusion in November 2023. The paper will present the major findings of this de-risk project and the resulting updates to pre-treatment and system design. One major update was the change to DCMD and the resulting significantly higher flux that the system could deliver. The acidification and pre-treatment procedures have been optimized and a continuing project focusses on building a full breadboard model. The advances in this will also be presented. Work on the MD subunit was continued throughout 2024 and in October 2024 ESA approved the continuation of the project with the aim of further developing the concept and constructing a full breadboard system. The paper and presentation will for ICES 2025 will include these further developments.