Bioregenerative recycling of wastewater in Biosphere 2 using a constructed wetland: 2-year results

During the 2-year closure experiment (1991-1993) inside Biosphere 2, a two-stage system comprising primary treatment in anaerobic holding tanks followed by circulation in constructed wetlands treated all human habitat and domestic animal barn wastewater, as well as effluent from workshops and medical/analytic laboratories. The system had an estimated hydraulic loading of 0.9-1.1 m(3) day(-1) (240-290 gal d(-1)). Plant production in the wetland treatment system was light-limited, but over the two years 720 kg dry weight of emergent wetland vegetation and 490 kg dry weight of floating aquatic plants were harvested from the 41 m(2) wetlands and used as fodder. The wastewater treatment system was part of overall strategy for nutrient recycling inside Biosphere 2 and effluent from the system was routed to the irrigation supply for the agricultural crops. The constructed wetlands enhanced habitat diversity, supported 14 species of vascular plants and provided aesthetic pleasure. Operation was batch loading, using both pumps and gravity feed. (C) 1999 Elsevier Science B.V. All rights reserved.