In Cape Cod, Massachusetts ... hidden away from the picturesque beaches was the town landfill, including lagoons of toxic waste from septic tanks, which was being left to seep into the groundwater below. So [John] Todd, then a 45-year-old biologist, decided to design a solution. Next to the lagoons, he assembled a line of 15 clear-sided fiberglass tanks, each about the height of a person, and filled them with water containing all the different life forms he could find from local ponds, marshes and streams plants, bugs, bacteria, fungi, general gunk. The water could be pumped from one tank to the next, and the living matter inside them soon organised itself into a series of different ecosystems. Todd found that he could put in polluted water from the lagoons at one end of the line of tanks and by the time it came out the other end, 10 days later, it was clean enough to drink. "To see that water, and to see all the organisms in the tanks, including fishes, looking and being so healthy, I was just amazed," he says. Todd ... would later discover that various microorganisms were finding uses for the toxins and heavy metals. Todd calls it "biological intelligence". Todd christened his invention the "eco-machine", and spent the next four decades ... applying it to everything from treating wastewater to growing food to repairing damaged ecosystems. Todd founded his own ecological consultancy, Ocean Arks International. It has designed and built more than 100 eco-machine systems to treat problems of pollution, wastewater and food production around the world, from the US to China, Australia, Brazil and Scotland. Todd's eco-machines are cheaper and more effective than industrial alternatives ... and are even capable of treating chemicals that have been impossible to break down using conventional methods, such as grades of crude oil and mining waste. They are also far more sustainable " powered almost entirely by sunlight.