PLANT POWER John Todd developed a process in the 1980s that mimicked natural ways to purify wastewater. Today, his Eco Machines and Restorers are used for a wide range of municipal and industrial applications.

John Todd founded Ocean Arks International in the 1980s, where he started to experiment with processes that mimic natural ways to purify wastewater. He built a greenhouse and ran sewage through a series of tanks, with plants suspended in the flowing waters, and constructed marshes made of sand and gravel. No chemicals were added, but plenty of aquatic creatures from snails to small fish were brought in at different stages to clean the waters.

Todd regarded his concept of Eco Machines - using ecological engineering to mimic natural processes to treat wastewater - as a start to "embracing a new relationship to the natural world which can sustain us all." Over the years he refined his ideas and broadened the scope of his thinking. Now he calls for "ecological and economic integration" where the whole concept of waste literally disappears, and is replaced by supplying materials as inputs to processes that create value for society.

Read more here.