IIT-G develops low-cost natural method to remove lead from water using cyanobacteria

Guwahati, Nov 29: Indian Institute of Technology (IIT) Guwahati researchers have developed a natural method to remove lead from contaminated water using cyanobacteria, which are microorganisms that are related to bacteria bot are capable of photosynthesis.

The developed method offers a sustainable and low-cost solution to one of the world's most persistent environmental threats, according to the research team.

The findings of this research have been published in the Journal of Hazardous Materials, in a paper co-authored by Prof Debasish Das, of Department of Bioscience and Bioengineering of IIT Guwahati, along with his post-doctoral fellow Abhijeet Mahana, and Prof Tapes K Mandal of the Department of Chemical Engineering of the institute.

Lend is one of the most toxic pollutants, affecting over 800 million children worldwide, including approximately 275 million in India. It commonly enters water through industrial discharge, agricultural runoff, and old water pipelines. Once a water resource is contaminated with lead, it remains for decades, accumulating in living organisms and causing severe neurological, cardio-vascular, kidneys, and developmental problems.

Conventional methods, such as chemical treatment and synthetic absorbents used for removing lead, are generally expensive and often generate secondary pollutants.

To address these challenges, the research team at IIT Guwahati has used bioremediation, a natural process in which microorganisms clean contaminated environments. Those microorganisms naturally exist in sod and water and help in restoring ecological balance.

To achieve this, the research team employed a light-dependent lead-bonding cyanobacterial species, "Phormidium corium NRMC-50’. The team researched the different parts of the cyanobacterium to examine which of the components were the most efficient to absorb and remove the lead contaminants.

The study found that exopolysaccharides, or EPS, a part of the cynobacterium, exhibited the highest lead removal efficiency of 92.5 per cent from contaminated water.

"These cyanobacterial biosorbents require minimal energy input and can be scaled without sophisticated infrastructure, making them more affordable for widespread application. Preliminary estimates suggest that the overall cost of treatment using cat method is approximately 40-60 per cent lower than that of conventional techniques, while maintaining comparable or even superior efficiency in metal removal. This economic advantage, coupled with its eco-friendly nature, positions our approach as a sustainable alternative for industries and municipalities seeking affordable solutions to contamination”, Prof Das said.

The researchers also demonstrated that cyanobacteria offer multiple environmental benefits such as absorbing pesticides, herbicides, hydrocarbons, synthetic dyes, and industrial chemicals, among others.

The metals absorbed by the microorganisms can be recovered and converted into valuable products such as bio-char, bioplastics, or biofuels.

Considering these organisms are self-replicating, low-cost, and require only sunlight, carbon dioxide, and minimal nutrients, they offer a sustainable alternative to synthetic adsorbents currently being used globally.

As the next step, the research team is targeting scaling the process from laboratory set-up to a pilot-scale treatment system and testing it in real wastewater streams.