Apparently Serbia, and especially Belgrade, has a huge problem with air pollution.

Ms. Francine Pickup, Resident Representative of the United Nations Development Program (UNDP) in Serbia, explained that: “It is estimated that cities are the source of as much as 75% of total CO2 emissions in the world, of which the largest percentage comes from traffic and cooling and heating in buildings”. She later continued to explain that 59% of the Serbian population lives in urban areas and that the number is constantly increasing. Because the population density is so high, creating green areas and planting trees – which represent natural air purification in urban areas– is a complex goal to achieve, as there is a lack of free areas for landscaping.

The microalgae replace two 10-year-old trees or 200 square meters of lawn. The function of the LIQUID 3 is practically an imitation of it. Both trees and grass perform photosynthesis and bind carbon dioxide. However, the advantage of microalgae is that it is 10 to 50 times more efficient than trees. The team behind LIQUID 3 has stated that their goal is not to replace forests or tree planting plans but to use this system to fill those urban pockets where there is no space for planting trees. In conditions of intense pollution, such as Belgrade, many trees cannot survive, while algae do not have a problem with the great levels of pollution.

The project is designed to be multifunctional. LIQUID3 is also a bench, it has chargers for mobile phones, as well as a solar panel, thanks to which the bench has lighting during the night.

Dr. Ivan Spasojevic also explained that “the Institute used single-celled freshwater algae, which exist in ponds and lakes in Serbia and can grow in tap water, and are resistant to high and low temperatures. The system does not require special maintenance – it is enough to remove the biomass created by dividing algae, which can be used as an excellent fertilizer, in a month and a half, pour new water and minerals, and the algae continue to grow indefinitely. This project aims to popularize and expand the use of microalgae in Serbia, because they can be used in wastewater treatment, as compost for green areas, for the production of biomass and biofuels, as well as for air purification from exhaust gases from the factories”.

[Image ID. Screenshot from twitter. User @pixelatedboat aka “mr tweets” (with an icon of a pixelated boat) wrote: “My goal is to be the first person dead inside one of these.”

pixelatedboat is responding to a tweet from the account @yupthtexists who wrote: “Scientists create Liquid Trees; a tank full of water and micro-algae that could be an alternative to trees in urban areas.”

Underneath is two photos of the tank in question: a rectangular green tank in a black frame of about human height. There is also an ivory bench attached to the tank. In the background is a street scene with cars, businesses, bike racks and trees. End ID.]

This is lovely.

Trees require dirt with good nutrients. One of the problems with “plant trees in cities” is that trees in cities are drinking water full that includes street runoff, and the dirt is soaked with exhaust fumes, oil, cleaning solutions, and random toxic chemicals.

Trees need sunlight - a stable amount of it, at the right times of day, at the right times of year. (Algae needs sunlight but it’s a lot less picky about it.) Trees have leaves that get shed… do you sweep them into the garbage? Try to gather them as mulch for plants that are nowhere near the trees? They grow branches that need to be trimmed for safety reasons - but not trimmed too much, because that can severely damage the tree. …And so on. Trees require conditions maintenance that an urban center may not be able to provide.

“Space that’s in the light sometimes and is big enough for a vat of green sludge” is much more available, and cities should be all over this.