IIT Guwahati researchers develop low-cost system to remove 99% arsenic from groundwater

New Delhi: Indian Institute of Technology Guwahati researchers have developed a new system that can effectively remove 99% arsenic from contaminated water at a low cost. The electrocoagulation system has demonstrated the ability to remove contaminants within a few minutes, making it suitable for use in regions with limited access to complex water treatment infrastructure.

Due to rapid industrialisation and urban growth, global reliance on groundwater has increased significantly. In many regions, groundwater contains arsenic released from natural rock formations or human activities such as mining and agriculture. Long-term exposure can cause serious health problems, including organ damage and cancer. Around 140 million people globally are exposed to unsafe arsenic levels, with India, Bangladesh, and parts of South America among the worst affected.

To address this, many conventional methods have been developed, and while some have been successful, these are difficult to implement in uncontrolled environments. Most methods rely on the addition of chemicals, extensive treatment periods, and sophisticated equipment. Moreover, the methods need to be performed on site and have the potential to create surplus sludge, increasing the time and energy costs to disposal.

Electrocoagulation offers a different approach. Instead of adding chemicals from outside, it uses an electric current to release metal ions from electrodes placed in the water. These ions attach to arsenic and other contaminants, allowing them to clump together and be removed from the water through settling or flotation. The process is relatively simple to operate and reduces the need for chemical handling.

Traditional electrocoagulation systems use stationary electrodes, which can slow the process and cause deposits to form on the electrode surface over time, reducing efficiency.

To overcome many of the noted system inefficiencies, the IIT Guwahati team, under the guidance of Prof. Mihir Purkait, Professor, Department of Chemical Engineering, IIT Guwahati, configured an electrocoagulation system with a rotating anode and a stationary cathode.

Speaking on the application of the technology for arsenic mitigation, Prof. Mihir K. Purkait from the Department of Chemical Engineering, IIT Guwahati said, “Electrocoagulation, combined with a rotating electrode system, offers an efficient solution for arsenic-contaminated water. “In this process, a controlled electric current dissolves a sacrificial iron electrode while its rotation enhances mixing and mass transfer, leading to uniform generation of iron coagulant species that effectively bind arsenic present in the water,” he explained. Simultaneously, fine gas bubbles formed during the process attach to the arsenic-laden flocs and lifts them to the surface for easy separation. According to Prof. Purkait, the use of rotating iron electrodes significantly improves removal efficiency while maintaining low operational cost, making the technology well suited for arsenic removal under optimised conditions.”

Laboratory tests using both synthetic water and real groundwater samples showed that the system could treat one cubic meter of contaminated water using only about 0.36 units of electricity. At prevailing electricity tariffs, this translates to a treatment cost of roughly Rs. 8–9 per 1,000 litres. Under optimised conditions, arsenic concentrations were reduced to well below the World Health Organization’s guideline of 10 micrograms per litre within two to three minutes. The rotating anode system also produced significantly less sludge than conventional electrocoagulation setups, with faster settling and easier handling.

The EC technology is a cost-effective alternative to conventional membrane and adsorption systems, particularly for arsenic removal.

• For a small community-scale plant (10–50 kilolitres per day), an EC system typically costs Rs. 8–15 lakh, while a conventional system costs between Rs. 12–20 lakh.

• At medium-scale capacities (100–500 kilolitres per day), the EC system costs Rs. 30–80 lakh, whereas RO-based systems often exceed Rs. 1–2 crore.

Operationally, the EC system does not require expensive membranes or frequent chemical dosing, and maintenance is largely limited to electrode replacement. In contrast, membrane systems include high operating costs due to membrane fouling, replacement, and energy-intensive operations.

The developed technology is particularly suitable for rural and semi-urban areas, where affordability, robustness, and ease of operation are critical.

The findings of this study have been published in prestigious Separation and Purification Technology Journal in a paper co-authored by Prof. Mihir Kumar Purkait and his research scholar Mr. Mukesh Bharti.

As the next step, the team plans to test the developed system in real-field conditions and evaluate its long-term performance in groundwater containing multiple contaminants such as fluoride and iron.

The research team is in discussion with M/S Kakati Engineering Pvt. Ltd., Sivasagar, Assam, for the fabrication and installation of the system. Further commercialization of the developed technology will be initiated once an appropriate funding source is confirmed.