Bioregenerative recycling of wastewater in Biosphere 2 using a constructedwetland: 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 follow ed by circulation in constructed wetlands treated all human habitat and dom estic animal barn wastewater, as well as effluent from workshops and medica l/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 tr eatment 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 pl ants were harvested from the 41 m(2) wetlands and used as fodder. The waste water treatment system was part of overall strategy for nutrient recycling inside Biosphere 2 and effluent from the system was routed to the irrigatio n supply for the agricultural crops. The constructed wetlands enhanced habi tat diversity, supported 14 species of vascular plants and provided aesthet ic pleasure. Operation was batch loading, using both pumps and gravity feed . (C) 1999 Elsevier Science B.V. All rights reserved.