In 1998, NASA announced it had built a human waste reclamation bioreactor designed for use in the International Space Station and a manned Mars mission.
The controlled partial oxidation of sulfide to elemental sulfur (2) is catalyzed by naturally occurring microorganisms of the genus Halothiobacillus in the bioreactor.
The bioreactor used in this project was custom made, based on an organ perfusion pump designed by Alexis Carrel and Charles Lindbergh.