Keywords: wastewater treatment, constructed wetland, global model
Global supply of freshwater: the role of treatment wetlands
In 2000, humans used approximately 60% of run-off that is geographically and temporally accessible. With projected increases in population, humans may use between 72-99% (depending on whether per capita increases are factored) of accessible run-off by 2025, even accounting for new dam construction. Wetlands have the capability to filter polluted water and could therefore potentially affect access to freshwater. Based on an estimated 2507 km³/year of total wastewater produced in 2025 and a standard flow rate of wastewater at 5 cm/day, our model predicts that the construction of 171,114 km² of treatment wetlands can potentially reduce human appropriation of annual run-off to 64% by 2025, with additional freshwater returns of up to 23% of annual run-off.