IIT Guwahati team finds blue-green algae can remove lead from water

GUWAHATI

A team of scientists from the Indian Institute of Technology Guwahati (IITG) have developed a biological material that can remove lead from contaminated water.

The team led by Professor Debasish Das of the Department of Biosciences and Bioengineering found that cyanobacteria, or blue-green algae, can be used to absorb lead from contaminated water. Such algae are available in village ponds, lakes, reservoirs, paddy fields, and slow-moving freshwater bodies in the country.

The study, co-authored by Professor Tapas Kumar Mandal of the Department of Chemical Engineering and postdoctoral fellow Abhijeet Mahana, was published in the latest issue of the Journal of Environmental Chemical Engineering.

During the research, the team found that exopolysaccharides (EPS), a sticky, sugar-rich material found in algae, absorbed the highest amount of lead from water.

“We found that the EPS organism can remove 66.2% of lead, one of the most toxic heavy metals, from polluted water. It can form associations with fungi to form cyanolichens (specialised lichens containing the blue-green algae), enrich soil by fixing nitrogen, and act as a natural bio-fertiliser to boost agricultural productivity,” one of the researchers said.

The researchers found that naturally occurring chemical groups in the material bind lead particles, making it effective at removing lead from contaminated water. They also found that the blue-green algae naturally change their chemical composition to capture lead.

The team plans to develop a scalable system that can be used for continuous treatment of water containing mixtures of toxic metals and industrial wastewater.

According to a 2020 report by UNICEF and Pure Earth, an international non-profit NGO, more than 275 million children in India have blood lead levels at or above hazardous levels. A subsequent report by the Central Ground Water Board said 20-30% of groundwater samples tested across major Indian cities exceed the World Health Organisation’s safe limits.

Conventional water treatment methods involving chemical precipitation, membrane filtration, or ion exchange processes are not only expensive and energy-guzzling but also generate secondary pollutants. The IITG team said the biological material it developed could offer a greener, renewable alternative to this problem.