Hydroponics Module is a self contained system for raising plant life that not only generates oxygen but also edibles. As with other modules, it has an airlock chamber in case it is not attached to an array of modules. The system is complete with lighting and air filters, and several internal tanks to store a back up reserve that isn't automatically channeled off for use in other modules. A Hydroponics Module can be used to either generate enough breathable air for five people, or enough food to sustain to five people (assuming multiple modules to provide a variety of environments to support multiple types of food, greens, fungi, etc).
Near Future: Lunar Colony Volume 1 is a set of models based around the theme of currently (or near future, within the next 20 years) envisioned technology used for populating our solar system. This isnt science fantasy or far far future, but what could be possible during the 21st century. This is the future as we know it now.