Also interesting on the spacecraft angle: Apparently spirulina will grow in dilute urine as a growth medium: "Attempts were made to culture Spirulina platensis

Also interesting on the spacecraft angle: Apparently spirulina will grow in dilute urine as a growth medium: "Attempts were made to culture Spirulina platensis in human urine directly to achieve biomass production and O2 evolution, for potential application to nutrient regeneration and air revitalization in life support system. The culture results showed that Spirulina platensis grows successfully in diluted human urine, and yields maximal biomass at urine dilution ratios of 140~240" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1361757/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1361757/