IIT Guwahati Develops Low-Cost Technology to Remove Arsenic and Fluoride from Groundwater

Researchers at the Indian Institute of Technology Guwahati (IIT Guwahati) have developed a low-cost water-treatment technology capable of simultaneously removing arsenic and fluoride from contaminated groundwater, offering potential for affordable drinking water treatment in affected regions.

The researchers have developed a rotating-anode electrocoagulation (RA-EC) reactor that achieved up to 98.2% removal of arsenate and 91.8% removal of fluoride within minutes. Initial demonstrations suggest that the technology can treat water at an estimated operating cost of Rs 18–58 per 1,000 litres, depending on the concentration of contaminants.

The development could have significant implications for rural and decentralised water-treatment systems, particularly in regions where groundwater contamination by arsenic and fluoride remains a serious challenge.

The findings have been published in the peer-reviewed Chemical Engineering Journal. The research paper was co-authored by Prof. Mihir K. Purkait and Mukesh Bharti from the Department of Chemical Engineering at IIT Guwahati.

Groundwater is a primary source of drinking water for millions of people across India. However, in several regions, naturally occurring arsenic and fluoride contaminate groundwater and pose serious long-term health risks.

According to Prof. Mihir Kumar Purkait, treating the two contaminants together has been particularly challenging because they behave differently during conventional purification processes and compete for removal sites. “Groundwater serves as the primary source of drinking water for millions of people across India. In several regions, however, it contains both arsenic and fluoride, two contaminants that pose significant long-term health risks. Treating them together has remained particularly challenging because they behave differently during conventional purification processes and compete for removal sites,” Prof. Purkait said.

To overcome this challenge, the IIT Guwahati team redesigned the conventional electrocoagulation process by introducing a rotating aluminium anode instead of a stationary electrode.

The rotating electrode improves mixing inside the reactor, enhances mass transfer, continuously renews the electrode surface and promotes the formation of aluminium hydroxide flocs that capture pollutants.

When electricity passes through the reactor, aluminium and hydroxide ions combine to form microscopic flocs. These flocs bind with arsenic and fluoride, enabling their removal through a combination of adsorption, coagulation and precipitation.

The rotating configuration also helps reduce electrode passivation, a common problem in conventional electrocoagulation systems, thereby improving the efficiency of the treatment process.

Tested under real conditions

The researchers evaluated the effect of several operating conditions, including rotational speed, current density, electrode spacing and treatment time.

Mukesh Bharti, Research Scholar at the Department of Chemical Engineering, IIT Guwahati, said the technology was also tested under conditions designed to reflect real groundwater chemistry. “We systematically evaluated how operating conditions, including rotational speed, current density, electrode spacing, and treatment time, influence performance. Our technology was also tested under realistic groundwater chemistry, including the presence of naturally occurring ions such as calcium, magnesium, bicarbonate, sulphate, and phosphate, as well as real groundwater samples collected from Assam,” Bharti said.

The technology could potentially be used for community drinking-water purification, decentralised rural water-treatment systems, treatment of arsenic- and fluoride-contaminated groundwater and industrial wastewater remediation. It could also be integrated with other treatment technologies such as adsorption and membrane filtration.

Focus on pilot-scale deployment

The next phase of the research will focus on developing a pilot-scale continuous-flow version of the reactor for practical deployment.

Future studies are also expected to incorporate sensor-based automated process controls for real-time monitoring of parameters such as pH, conductivity, electrical current and rotational speed.

If successfully scaled up and deployed, the technology could provide an affordable treatment option for communities dependent on contaminated groundwater, particularly in areas where access to safe drinking water remains a persistent challenge.