Viet Ngo/Lemna International, Wastewater Treatment Pond, 1993, Cleveland, Georgia

Part bio-engineer, architect, and artist, Viet Ngo first began designing and building wastewater treatment plants that use his patented LemnaTM System (lemna is popularly known as duckweed) in 1983. Rather than use mechanical or chemical processes, Ngo's system uses small floating aquatic plants grown in specially designed ponds to treat waste to a very fine degree.

http://www.lemna.com/