Applications of pulsed UV-light processing for ISS and planetary outposts

The need to sanitize recycled water, crops and foods produced on ISS and planetary outpost, Moon or Mars, is critical for astronaut survival. Several novel processing methods need to be investigated. A system built around the pulsed ultraviolet (UV) light sterilization concept is one such technique to specifically address rapid microbial inactivation. The application of pulsed UV-light treatment on suspension cells, agar seeded cells, honey, milk, corn meal, and sprouting seeds is being investigated for inactivation of pathogenic or spoilage microorganisms. The treatment is being optimized for operational parameters such as number of pulses, distance from UV lamp, and depth of penetration. Five second treatment time resulted in the 7.50 log₁₀ reduction for suspended and agar seeded Staphylococcus aureus, whereas 1 log₁₀ reduction was observed for S. aureus in milk even at 60 sec treatment. Similarly, less than 1 log₁₀ reduction was observed for Clostridium sporogenes spores in honey. Up to 5 log₁₀ reductions of Aspergillus niger in corn meal and E. coli 0157:H7 on alfalfa seeds and were obtained for 100 and 90 sec treatments, respectively.