Over the past few weeks I have been reading about Liquid Trees, specifically the LIQUID 3 Bioreactor, a human made bioreactor that uses alge and employs the natural process of photosynthisis to capture CO2 and emit oxygen. I was struck by the implications. What on earth is going on? Why not simply plant more trees? Why use a contraption to do what nature already takes care of so easily?
In cities where green areas are sparse, combating pollution is a challenge, and liquid trees might be a part of the solution. Planting trees, or reforestation is commonly used to capture CO2 and produce oxygen for better air, and there has been much activity with government programs and small business startups trying to help. But not all locations are condusive to tree planting. Many highly-urbanized ares have such high levels of air, soil and groundwater pollution that they won’t grow. Other areas have water insecurity so caring for trees, especially in their most vunerable period of early growth becomes an issue. Recently, a group of Serbian scientists developed an innovative technique to address these issues – the LIQUID 3 bioreactor or liquid tree.
Why Liquid Trees in Serbia?
Belgrade, Serbia, a city with two large coal power plants, is one of the world’s most polluted cities. These power plants were recognized in the 2019 Health and Environment Alliance’s list of the 10 filthiest plants in Europe. Serbia stood at 28th place in 2020 in the world’s worst air quality list, with a PM 2.5 concentration 4.9 times above the WHO’s yearly air quality guideline. Consequently, the country’s inhabitants suffer from severe health effects from pollution, and the highest pollution-induced deaths.
Urban areas contribute approximately 75% of worldwide CO2 emissions, with transportation and building heating and cooling accounting for the majority of it. In Serbia, the population living in urban regions is constantly increasing and currently stands at 59%. Given the high population density, planting trees, which are natural air purifiers in urban regions, and creating green spaces is challenging.
Researchers at the University of Belgrade, have devised an innovative method for decreasing greenhouse gas emissions and enhancing air quality – the liquid tree, also known as LIQUID 3 bioreactor. The LIQUID 3 bioreactor is Serbia’s initial urban photo-bioreactor, employing microalgae to absorb CO2 and produce pure oxygen through photosynthesis.
How does a LIQUID 3 bioreactor work?
The LIQUID 3 bioreactor is an imitation of trees and grass and is equal to two ten-year-old trees or 200 square meters of grass, which both undergo photosynthesis and consume CO2. Microalgae, on the other hand, are 10 to 50 times more effective than trees. The LIQUID 3 bioreactor’s primary objective is not to replace forests or tree planting plans, but rather to fill urban areas where planting trees is not possible due to space constraints or high pollution levels.
The first LIQUID 3 bioreactor is located on Makedonska Street in Belgrade, in an area with high CO2 emissions. The unit uses single-celled freshwater algae, which can thrive in tap water and tolerate extremes in temperatures. The LIQUID 3 bioreactor requires minimal maintenance; the algae only needs to be separated from the water every 45 days and produces an excellent fertilizer. The project’s aim is to promote and expand microalgae use in Serbia, and when scaled up can be used for wastewater treatment, compost for green areas, biomass for biofuel production, and exhaust gas air purification.
Does a LIQUID 3 Bioreactor add anything to the community?
The unit has an attractive design; it is powered by a solar panel and has a low wattage lighting system to provide security as a night light. It enhances the urban area where it is located, and in keeping with the human focussed nature of the device, there is a bench for passers by to relax, with USB ports for people to recharge their mobile devices.
The LIQUID 3 bioreactor doesn’t replace trees, it creates a new way of purifying air, sequestering carbon, cleaning water and highlights the importance of promoting climate-smart urban development. We can ensure better solutions for a positive impact in all sectors by engaging civil society, the public, and businesses to create new and innovative climate change mitigation techniques.
So back to the initial question? Is it an abomination or a part of the solutions we need for a bright green future? Your comments are welcome and I would love to hear your feedback below.