Single human produces around 1kg of CO2 per day: https://www.sciencefocus.com/planet-earth/how-much-does-huma...

Seems that algae are up to 400x more efficient at CO2 scrubbing than terrestrial plants. See: https://newatlas.com/environment/algae-fueled-bioreactor-car...

No idea though if such bio-tanks are a viable solution in a rather devoid of solar light shelters.