evidence: The BIOS-3 facility in Siberia was a sealed 315m3 habitat used in the 1970s to research exactly this. The system used tanks of Chlorella algae, rather than plants and 8m2 of exposed Chlorella was enough to maintain a balance of CO2 and O2 for one person. The longest experiment in BIOS-3 was with a three-man crew for 180 days.