Researchers at the Council of Scientific and Industrial Research-Central Institute of Mining and Fuel Research (CSIR-CIMFR) said they have developed a mobile “liquid tree”, an air-purification system that offers a solution for polluted urban areas where planting conventional trees is difficult.
Called the Smart Algal Liquid Tree, or SALT, the compact system has already been installed at the CSIR-CIMFR campus in Dhanbad and at Northern Coalfields Limited in Singrauli, Madhya Pradesh.
But what exactly is a liquid tree, and how can algae help clean polluted urban air?
What is a liquid tree and how is SALT different?
A liquid tree is essentially a container filled with water and microalgae. Microalgae are microscopic, single-celled organisms that typically live in waterbodies. They use sunlight to convert carbon dioxide into oxygen and are responsible for generating about half of the global oxygen, according to ScienceDirect.
Like plants and trees, microalgae use light and carbon dioxide to grow. During this process, they absorb carbon dioxide from the surrounding environment and release oxygen.
A liquid tree puts this biological process inside an enclosed, compact unit that can be installed where there is little room for conventional trees.
Unlike earlier fixed liquid-tree installations, SALT is designed to be mobile, allowing deployment in different urban and industrial locations.
How does a liquid tree reduce air pollution?
The process is similar to photosynthesis:
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Air containing carbon dioxide comes into contact with the algae-based system -
The microalgae use light to absorb carbon dioxide during photosynthesis -
Oxygen is released as a by-product of the process
In many designs, polluted urban air is drawn or bubbled through the tank. As the air interacts with the liquid and algae, some pollutants can be trapped, absorbed or biologically processed. This helps reduce pollution in the atmosphere.
“The primary purpose of this innovation is to combat poor air quality in densely populated and space-constrained urban areas where there is little or no room to plant large trees,” Vetrivel Anguselvi, senior principal scientist at CIMFR who led the project, told news agency PTI.
SALT can also operate with artificial light, allowing the biological process to continue even when sunlight is unavailable. The unit can run on solar power as well as electricity.
Can liquid trees replace real trees?
No. Liquid trees are mostly designed for places where conventional plantation is difficult because of a shortage of space.
Real trees don’t just produce oxygen. They support biodiversity, provide shade, cool urban areas, absorb rainwater and contribute to ecosystems.
SALT instead seeks to use the carbon-absorbing ability of microalgae in a smaller physical space. Its developers say the enclosed system does not require soil, needs little maintenance and is less vulnerable than conventional trees to pests and harsh urban conditions.
Where could SALT be used?
SALT is designed for use in densely populated and space-constrained areas where poor air quality coincides with limited room for large-scale tree planting.
CSIR-CIMFR sees potential for the system at transport hubs, industrial sites, educational institutions, shopping centres, parks and other crowded public spaces.
The institute is also exploring commercial production of the device. Researchers are working to make it affordable enough for possible use in residential areas and localities facing severe air pollution.
