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August 11, 2021
University of Helsinki
KAUTE Foundation grant recipient Anjan Deb develops photocatalytic thin films for drinking water purification. New technology would make drinking water treatment more accurate and environmentally friendly.
Anjan Deb became interested in water technology in Bangladesh, where drinking water scarcity is one of the biggest societal challenges.
“There are over 2 billion people in the world who don’t have simple access to pure drinking water. There are many challenges for water purification, and in my research I want to solve these challenges by creating sustainable solutions.”
Deb moved to Finland to pursue a master's degree at Lappeenranta-Lahti University of Technology in 2016. After graduating, he continued at the university as a researcher in a pilot project in which he was involved in the development of a purification process based on membrane bioreactor or MBR technology at the Mikkeli wastewater treatment plant.
With a grant from the KAUTE Foundation in 2020, Deb is now developing a photocatalytic thin-film for the purification of drinking water at the University of Helsinki. Thin films are a solid thin layer of photocatalytic material that excites under the illumination of sunlight and generates highly reactive oxygen species. These reactive oxygen species are capable of breaking down the harmful substances from water.
“This is a promising sustainable technology; however, it is facing many challenges for commercialization in water purification applications. My goal is to develop this technology so that it can be widely exploited.”
Chemical purification methods such as UV, chlorination, ozonation and hydrogen peroxide-based oxidation processes are the currently practised water disinfection methods. However, they are not very environment friendly, some require strong safety measures and they can also be difficult to control. Also, they are not always effective enough to eliminate all the contaminants: for example UV resistant chemicals cannot be eliminated from the water using only UV light.
“The photocatalytic process makes it possible to decompose very persistent contaminants from water, such as chemicals used in sunscreens that are UV resistant and difficult to decompose with other methods.”
In his research project, Deb aims to develop highly active and stable photocatalytic thin films. His goal is to make thin films more durable using atomic layer deposition techniques so that it retains its catalytic activity over time. The project began in January, and Deb has already received preliminary results.
“Because photocatalytic thin films activate under sunlight, which is easily accessible and renewable, they have a lot of potential. This technology is also very environmentally friendly because it does not need any other chemicals to purify the water. I believe there is a huge potential for commercialization of this technology in the future.”
The field of water technology is roughly divided into two branches: the treatment of surface or groundwater for drinking or other domestic or industrial application and the treatment of wastewater generated from the domestic sector or industry for water recovery, reuse or safe disposal to the environment. According to Deb, the circular economy is a strong upward trend in wastewater treatment.
“Wastewater is no longer just waste, instead we can extract valuable nutrients, materials and energy besides clean water for reuse.”
In the future, the technology developed by Deb could be used to make wastewater potable.
“In the pilot project at Mikkeli’s wastewater treatment plant our aim was to purify the wastewater to drinking water, but we needed more efficient technologies. In the future, photocatalytic water purification technology could be an acceptable solution that can be used in water treatment plants all over Finland.”