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Living machines to purify wastewater

3 min


Rather than using chemicals to treat wastewater, an American biologist has chosen to imitate nature.


Nature offers many benefits for man: it supplies water, food, and building materials, it sequesters carbon dioxide, regulates climates, recycles organic waste, pollinates crops, and naturally purifies water. It is this last benefit that American biologist John Todd based his work on to imagine "living machines" that recycle wastewater through the combined action of a variety of living organisms.

A "living machine" is a self-sufficient polluted water treatment and phyto-purification system that mimics the natural purification process of rivers and wetlands. Part natural, part artificial, the system relies on a series of basins, each forming a specific ecosystem, connected by pipes and containing hundreds of plant and animal species (varying in size from bacteria to trees) which coexist in perfect symbiosis.

The whole system is based on a food chain. As wastewater passes through this system, it is exposed to various living organisms which feed on pathogens and pollutants.

Strange machines

Bacteria transform organic matter, such as ammonia, into nitrates. These are assimilated by algae which serve as food for zooplankton and snails. Fish eat zooplankton and their feces, which is rich in nitrogen, phosphorus, and potassium, are a source of nutrients for plants, such as rushes, reeds, and hyacinths that purify the water in the basin. This amazing ecological machine works with solar energy!

Innovation and phytoremediation

John Todd's strange machines are a perfect example of phytoremediation, which is the name given to all technologies using plants to eliminate or control soil, water, or air contamination from human activities. This innovative approach to water management has won numerous awards.

Since the creation of JTED (John Todd Ecological Design) in 1988 to promote ecological engineering systems and to sell them under the name "Eco-Machine", John Todd has installed living machines all over the world.

The biologist has proven that natural water purification systems are viable in different settings and at all latitudes from domestic and industrial wastewater treatment to the remediation of highly contaminated aquatic environments. Nature still has a lot to teach us!