JU researchers unveil ‘Liquid Tree’ to combat urban CO2 pollution

As Dhaka grapples with shrinking greenery and rising carbon dioxide levels, researchers at Jahangirnagar University have introduced a biotechnology innovation called the "Liquid Tree"—a photobioreactor designed to reduce CO2 emissions and increase oxygen levels in both indoor and outdoor environments.

The device was formally presented at a seminar titled "IoT-Based Smart Liquid Trees for Carbon Footprint Mitigation in Dense Urban Areas of Bangladesh", held on August 25 and organised by the Department of Biotechnology and Genetic Engineering at JU.

Researchers explained that the Liquid Tree is a transparent unit filled with microalgae that absorb carbon dioxide and release oxygen through photosynthesis. Outdoor models operate using sunlight, while indoor versions rely on artificial light.

The JU team has developed two distinct designs to address pollution in different settings. The outdoor model is compact and suitable for sidewalks, rooftops, road dividers, and parking spaces—targeting emissions from vehicles and industrial sources. The indoor model is tailored for classrooms, offices, and conference halls, where it absorbs CO2 exhaled by occupants and improves air quality, potentially enhancing concentration and productivity.

Unlike natural trees, which take years to mature, Liquid Trees can be built and installed within weeks. They also produce microalgal biomass, which can be used as fertilizer or biofuel. Indoor models can operate continuously with artificial lighting.

The research team adapted the design for Bangladesh using native algae strains and developed indoor models—an area still largely unexplored globally.

Speaking at the seminar, researchers acknowledged challenges such as the need for consistent light, water supply, and regular maintenance. However, they emphasised the broader benefits, including job creation, support for green industries, and contributions to sustainable urban planning.

They clarified that Liquid Trees are not intended to replace natural greenery, but rather to serve as a practical solution in areas where planting is not feasible—particularly in dense urban zones and sealed indoor environments.

The project was conducted under the supervision of the Research Innovation Centre at JU (RIC-JU) and funded by the World Bank. The lead researchers include Professor Dr Golam Moinuddin of JU's Urban and Regional Planning Department, Professor Dr Mohammad Shahedur Rahman of the Biotechnology and Genetic Engineering Department, Professor Dr M G Sorwar Hossain of BRAC University's Electrical and Electronic Engineering Department, and M Shakilur Rahman of EPL Solutions, USA.