WHERE TREES FEAR TO TREAD

BELGRADE'S LIQUID 3 USES MICROALGAE TO CLEAR THE AIR IN DENSE URBAN JUNGLE

- DAMIEN MARTIN

Trees are natures great air filters. They take in CO2 and churn out oxygen, a boon to living things all around them. They beautify landscapes and help make cities livable. There are pushes to plant as many trees as possible, trillions of them, to fight climate change and pollution-related disease. But there are some settings where planting a tree isn’t the best course of action and there’s a better weapon to clean up the air. The Serbian capital, Belgrade, is one such place, and there the city is deploying what its creators call LIQUID 3 and what others have dubbed a “liquid tree.”

LIQUID 3

The LIQUID 3 system, designed by researchers at the Institute for Multidisciplinary Research at the University of Belgrade, consists of a 600-liter tank of water with a microalgae that takes in carbon dioxide and produces oxygen through photosynthesis much like trees do, but anywhere from 10 to 50 times more efficiently. A single tank can yield as much O2 as two decade-old trees or 200 square meters (2,150 square feet) of grass.