Investigation of Silver Biocide as a Disinfection Tehcnology for Spacecraft – An Early Literature Review

An ideal spacecraft water disinfection system should prevent or control microbial growth, inhibit or prevent biofilm formation, and prevent microbial-induced corrosion. In addition, the selected biocide system should be chemically compatible with materials used in the water storage and distribution system, have minimal maintenance requirement, especially for long-duration missions, and should be safe for crew consumption at levels appropriate for biocidal control. Silver ion is a proven broad spectrum biocide. Terrestrially, there has been an increased interest in the biocidal function of silver, both due to its potential to control bacterial resistant species and due to advances in silver and nano-silver biocide technologies. NASA is considering silver as the future biocide for exploration over the current iodine state-of-the-art (SOA) biocide system. In order to select and design a successful silver biocide delivery system to meet NASA’s requirements, it is essential to understand the advantages and disadvantages of moving to a silver disinfection system. To enhance the knowledge base for the application of silver biocides in spacecraft water systems, this paper provides a first compilation of review data related to: (1) Silver as a biocide technology, (2) Options and concepts for silver biocide delivery, and (3) Silver biocide compatibility studies for spacecraft systems.