In the TED Talk below, Jane Poynter discusses her experience living for two years (plus 20 minutes) in Biosphere 2 in the early 1990s. In short, the experiment was to find out how to create a sealed, self-sustaining ecosystem. This was a huge challenge, and ultimately they had to add oxygen to the environment to make it work (more on that in the talk). Poynter talks about the Biosphere 2 experiment in some detail (as much as fifteen minutes allows), complete with lots of photos and personal recollections about it, including how she turned orange from eating too many sweet potatoes, what it was like living in a low-oxygen environment, and how people smelled in the "outside world" when she finally left the experiment.
Biosphere 2 still stands (near Tucson, Arizona) and science still goes on there, though nobody is sealed inside at the moment. If you're in the neighborhood, I urge you to take a tour -- it's a stunning place (particularly the underground "Technosphere"). Even if you're not there, check out b2science.org for lots of info.