Researchers at IIT Guwahati come up with sustainable method for lead removal from acidic waste water

Researchers from IIT Guwahati have done it once again, they developed a biological process to extract lead from acidic industrial waste water.

It is interesting to note that the biological process makes use of naturally occurring bacteria to extract lead.

Major source

It is known that waste water generated at the time to battery recycling is big source of lead pollution.

Exposure to lead is not a good one. As per the report of WHO - World Health Organization, exposure to lead can have a negative impact on cognitive development in children.

It can also do a good deal of damage to the nervous system and lead to many health issues in the long-term. 

Conventional method

As per the conventional system,  lead containing wastewater is treated using chemical processes, which are time-consuming and produce large amount of lead-containing sludge. 

This sludge needs to be disposed separately, say sources from IIT Guwahati. To address these challenges, Prof Pranab Kumar Ghosh along with his research scholar Sreekanth Yadav Golla have made use of the capabilities of sulphate-reducing bacteria, a group of microorganisms that grow naturally in oxygen-free environments.

About the work

Prof. Pranab Kumar Ghosh, Professor, Department of Civil Engineering, IIT Guwahati said 

sulphate-reducing bacteria convert sulphate in wastewater into sulphide.

This sulphide then reacts with lead dissolved in water to form lead sulphide, a solid mineral that can be easily removed, he said. 

The process also reduces the acidity of the wastewater, creating better conditions for the bacteria to survive and improving overall treatment efficiency, he said. 

Challenge

There is however one challenge that comes in these biological treatment. And, that is the microorganisms’ ability to survive in high acidity and metal concentrations in wastewater. 

To counter this, the research team from IIT Guwahati developed a process that gradually acclimatised the bacteria to increasingly extreme conditions.

The biological reactor removed lead from water using this approach. 

It also converted lead into solid  stable lead sulphide form. This allowed the microorganisms to continue treating the wastewater effectively.

Also, the amount of lead-containing sludge produced in this process was lower in comparison to the conventional methods.

Bio-sludge 

Sreekanth spoke about the bio-sludge. They examined the bio-sludge generated as a part of the treatment process to determine its environmental safety, he said.

Most of the lead in the sludge was present in stable forms that do not easily move or dissolve, he said.

Leaching tests

Also, the research team undertook leaching tests, these tests brought out that only very small quantities of lead were released from the sludge with concentrations remaining below regulatory limits, say sources from IIT Guwahati.

As a result, the bio-sludge may be safely disposed of in engineered municipal landfills, helping minimise long-term environmental risks associated with lead contamination.

The findings of this research have been published in the prestigious Journal of Environmental Chemical Engineering.

It is notable that beyond battery recycling facilities, the developed process can be utilised for treating wastewater from mining, smelting, and metallurgical industries.

Next step

As a next step, the researching team has plans to work on enhancing economic viability by using low-cost carbon sources, minimising sulphide in the treated water, and exploring potential metal recovery.

About IIT Guwahati

IIT Guwahati, established in 1994, completed 25 years of glorious existence in 2019. At present, the Institute has eleven departments, nine interdisciplinary academic centres and five schools.

These are covering all the major engineering, science, healthcare, management, and humanities disciplines, offering BTech, BDes, BSc(Hons), BS, MA, MDes, MTech, MSc, MS(R), MBA, PhD, and postdoctoral programmes.

The institute offers a residential campus to 455 faculty members and more than 8,600 students at present.

IIT Guwahati has gained the 8th position among the best engineering institutions of the country, 11th position in ‘Overall’ and 10th position in ‘Research’ Categories in the ‘India Rankings 2025’ declared by the National Institutional Ranking Framework (NIRF) of the Union Ministry of Education.

IIT Guwahati has achieved rank 87 in the SDG 9 (Industry, Innovation, and Infrastructure) globally in the Times Higher Education (THE) Impact Rankings 2024 and is the only academic institution in India that occupied a place among the top 100 world universities – under 50 years of age – ranked by London-based Times Higher Education (THE) in 2014 and continues to maintain its superior position even today in various International Rankings.

IIT Guwahati gained rank 42nd globally in the ‘Research Citations per Faculty’ category and overall, 334 rank in the QS World University Rankings 2026.

Among other frontier areas of research and innovation, IIT Guwahati is working towards augmenting critical science research initiatives in Genomics, Developmental Biology, Health Care and Bioinformatics and Flexible Electronics, among numerous other areas.

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