John Todd Ecological Design is a provider of biological systems for waste-water treatment. The basic element of the technology is what Todd calls an "Eco-Machine." Requirements for its operation include light and temperature above 50 deg F. While the treated water is not potable, it is similar to reclaimed water, suitable for final treatment with membrane technology.
In Tucson, Arizona, we have instances of water well failure driving small communities and isolated commercial entities to the brink. Centralized public water service is limited by a municipal policy cautious about over-committing scarce resources. The obvious solution is to recycle water locally and use limited well supply and rainwater harvesting for makeup. SpaceFarers Corporation is interested in doing just that with Alien Landscapes, a simulated space colony theme park to be built north of Tucson.