Bioelectrochemical Oxidation Of Urea With Urease And Platinized Boron Doped Diamond Electrodes For Water Recycling In Space Applications

The recovery of potable water from spacecraft wastewater is critical for the life support and environmental health of crew members in long-term missions. NASA estimates that during manned space missions 60 g/person.day of urine is produced, with urea and various salts as its main components. In this research we explore the utilization of urease enzymes (EC 3.5.1.5) to convert urea to nitrogen using a two step process of urease catalyzed decomposition of urea to ammonia followed by the electrochemical decomposition of ammonia to nitrogen. Urease was immobilized on granulated activated carbon to serve as a bio-reaction platform, while platinum was electrodeposited on boron-doped diamond electrodes by cycling the potential to attain active electrodes. Samples from NASA Ames Research Center water recycling equipment, containing urine, were used to test the herein proposed system.