In a quiet Kuruabahi village nestled in Assam’s Golaghat district, families rely on tubewells for their daily water needs, just as they have for generations. But what flows from these wells isn’t just water. It’s contaminated with arsenic, a toxic element present at levels reaching up to 344 ppb as opposed to 10 ppb; that is over 30 times higher than what the World Health Organisation deems safe. Assam continues to be one of the top hotspots for arsenic contamination of groundwater in the country.
Several government initiatives, including the Jal Jeevan Mission, and techniques such as ion exchange, reverse osmosis (RO), ultrafiltration, adsorption, and coagulation technologies are available at the household level to remove arsenic from drinking water. However, these solutions often fall short in rural settings as most are expensive, depend on electricity and produce large volumes of sludge. They are often found to be unsustainable and low in efficiency making them impractical for widespread use in remote, underserved communities.
Prolonged consumption of this invisible poison can lead to serious health problems like arsenicosis - causing skin lesions like melanosis (darkening of the skin) and keratosis (thickening of the skin), rain-drop syndrome and vitiligo (both whitening of the skin); damage to internal organs; and can lead to vomiting, abdominal pain, and diarrhoea in acute cases. It can also increase the risk of various types of cancers, cardiovascular diseases, and diabetes; impede cognitive development; and increase deaths in young adults.
However, hope is around the corner with a unique rural cost-effective technology, Arsiron Nilogon, that is extremely efficient in removing arsenic from drinking water, rendering it safe to drink while also being easy to use, sustainable in the long run, and environmentally friendly.
The Arsiron Nilogon technology was developed and patented in 2017 (Indian Patent No. 280737) by Professor Robin Kumar Dutta and his team at the Department of Chemical Sciences, Tezpur University, Assam. The Arsiron Nilogon method has been independently verified, and its findings published in several international research journals. Explaining the name, Professor Dutta informs, “The word ‘Arsiron’ represents ‘arsenic’ and ‘iron,’ while ‘Nilogon’ means ‘removal’ in Assamese.”
The motivation behind the innovation, he says, was deeply personal: “I decided to work on the removal of arsenic, as I was deeply affected by the rising incidences of cancer in Majuli area, where I come from. I know how it feels to lose family and friends to deadly water contaminants. Because of my background in physical chemistry, I knew how to play with chemicals. I took cues from nature to develop this technology.”
What is the Arsiron Nilogon method?
Professor Robin Kumar Dutta explains, “Arsiron Nilogon is a technique that removes both arsenic and iron from contaminated water. It utilises a three-step chemical process that involves the use of three easily available and low-cost chemicals, such as baking soda, potassium permanganate, and ferric chloride, to treat arsenic-contaminated water. Baking soda helps to adjust the pH of the water, allowing the chemical reactions to work better. Potassium permanganate acts as an oxidising agent, converting dissolved arsenic (primarily arsenite) into a less harmful form (arsenate) and converting dissolved ferrous iron into insoluble ferric iron oxide. It catalyses the oxidation of arsenic from a difficult-to-remove arsenite form to an easy-to-remove arsenate form.”
He continues, “Ferric Chloride acts as a coagulant, producing solid iron oxide particles, helping the arsenic to stick to the iron particles, settling down as clumps. A sand-gravel filter is used to remove the larger particles of iron oxide along with arsenic, resulting in clean, safe drinking water. In essence, Arsiron Nilogon creates conditions that favour the removal of arsenic and iron by oxidation, coagulation and adsorption, making it a simple yet effective method for water purification.”
There are two options while using Arsiron Nilogon to purify water that is contaminated with both arsenic and iron. The dissolved iron can be first removed by sand-gravel filtration and then treated with Arsiron Nilogon or both can be removed together with a modified dose of chemicals. Utilisation of the existing dissolved ferrous iron from the water by converting it to ferric oxide can help reduce the cost of the chemicals. It has been found that Arsiron Nilogon can also remove manganese, lead, mercury, and other heavy metals and also helps in regulating the pH of water at 7.3 – with the acceptable pH range for drinking water in India as per BIS, being 6.5 to 8.5.
“We have used this method most successfully in Majuli and other districts of Golaghat, Jorhat, Lakhimpur, Sonitpur, Nagaon and Baksa in Assam. We have also installed filters at Mrinaljyoti Rehabilitation Centre in Duliajan town in the Dibrugarh district of Assam, where the neurotoxic effects of manganese, lead, and mercury present in drinking water were adding to the plight of around 300 physically and mentally challenged children diagnosed with neurological disorders. Thanks to OIL CSR support, they have been getting safe drinking water through two 1000 L Arsiron Nilogon filters for the last four years,” says Professor Dutta.
Three hundred and twenty filters were installed at the Kuruabahi village in Golaghat district recently with CSR support from NRL. Few filters have been installed at some places in other states also, such as Bashirhat in South Paragana (WB), Anantapur in Mirzapur (UP), and Darbhanga in Bihar. “INREM foundation has also tested and used this method in the Nalbari district in Assam. Mr. Gautam Anand, who works for the foundation, also helped us in installations at Simri and Brahmpur in the Buxar district in Bihar,” he adds.
The team recently conducted a study titled, ‘Effectiveness, user acceptability and sustainability of Arsiron Nilogon: a rural technology for arsenic removal from drinking water’ in Kuruabahi village in the Golaghat district in Assam that aimed at assessing the long-term performance, sustainability and user acceptance of the technology as a part of a large-scale community intervention for arsenic mitigation. Three hundred twenty household filter units were installed as a part of the study in the village, and participants were trained in the use of the filters through workshops and regular follow-ups.
The filter material included a 40L plastic drum fitted with a plastic tap for sedimentation of arsenic, a 16L plastic bucket fitted with a plastic tap, twenty kg of sand, some gravel for making a sand-gravel filter, and an iron stand for placing the filter. The kit included 500g of baking soda (cooking soda, NaHCO3), 200 mL of 5 percent (w/v) aqueous potassium permanganate (KMnO4), and 500 mL of 25 percent (w/v) aqueous ferric chloride (FeCl3). A small poster providing information on the process to be followed was also included along with the filter kit. Regular follow-up visits were made as a part of the study to assess the usability and acceptability of the filters among the villagers over a period of two years.
The study found that:
Widespread contamination of groundwater by arsenic was evident in Kurubahi village
Tube wells formed the prime source of water in all the households, and it was found that arsenic contamination of groundwater was widespread in the village, with the highest value being up to 344 mg L⁻¹, much above the WHO guideline value of 10 mg L⁻¹ for drinking water. Number of households with arsenic in drinking water in different concentration ranges can be seen in the figure below.
Among 320 households, 5 percent of households were found to be consuming water contaminated with a very high concentration of arsenic, i.e., above 100 ppb while 65 percent of households were found to be consuming water with arsenic above the WHO guideline of 10 ppb.
The filters were highly effective in removing arsenic from water
The filters were found to be highly effective in bringing down arsenic concentrations from as high as 344 mg L−1 to being undetectable or below 2 mg L⁻¹. The pH of all the treated samples was found to be 7.3 (±0.2), which was within the acceptable range of 6.5–8.5 for drinking water, as specified by the Bureau of Indian Standards (BIS). Among heavy metals, only iron was found to be present in the range of 1.69 ppm to 5.54 ppm in the water before treatment. Other heavy metals like manganese, nickel, cobalt, chromium and aluminium were below the detection limit and below the WHO guideline values.
The water showed improved taste and health benefits
“Relief from chronic acidity was one of the major health benefits observed in the people drinking water from the filters. Individuals from the Chinakan, Adarsha Gaon, Rongagora and Singadoria habitations of the village experienced relief from acidity at varying percentages: 16 percent, 13 percent, 29 percent, and 15 percent, respectively. Many of the villagers reported that they found the taste of the treated water to be better than before. This is because of the slight increase in benign carbonate ions in water due to the addition of cooking soda, sodium bicarbonate, to regulate the pH for facilitating arsenic removal,” inform the authors of the study.
The acceptability of filters was high
The villagers were very regular in refilling the potassium permanganate and ferric chloride solutions and buying the cooking soda, showing the acceptability levels and assurance that Arsiron Nilogon filters would be used in the long term by the villagers.
The filters were found to be economically and environmentally sustainable
The capital cost of a 40L household Arsiron Nilogon at Kuruabahi worked out to be US $9.52. Taking into consideration the estimated filter lifetime of ten years and recurring and capital costs, the direct cost worked out to be US $10.865.
A small amount of sludge generated following the filtration process was collected in an earthen pot containing sand and a small hole at the bottom by the villagers to filter out the harmful residual contents in the sludge. The sludge passed the toxicity characteristic leaching procedure (TCLP) test of the United States Environmental Protection Agency (US-EPA) and was found to be suitable for dumping in a landfill. The test also showed that the arsenic concentration in the leachate of the sludge sample was very low as compared to the TCLP limit of USEPA.
The villagers were advised to bury the sludge at a safe place so that the arsenic could not leach into the water. During the follow-up, it was found that all the households followed the sludge disposal method as advised.
The Arsiron Nilogon filter has potential for scalability
The assessment of social, economic, and environmental factors revealed that besides being low-cost, Arsiron Nilogon filter was a safe, effective, and sustainable choice for use in rural households and has potential for scalability. However, it is important to remember that it relies on user awareness and knowledge and correct operation of the method. Proper training and monitoring can greatly help in maximising the advantages of this method in settings where arsenic contamination of water is high.
Professor Dutta says, “Our motto is, ‘Give a fish to a man, and he will eat for the day; teach him how to fish, and he will eat for his life.’ We empower people to get arsenic-free water on their own by making the Arsiron Nilogon filter and using it at a minimum cost without depending on others to supply water to them. The Arsiron Nilogon filters can be a stop-gap arrangement until surface water is supplied and also a stand-by system for use during breakdown of surface water supply.”
The details of the chemical doses that can be used to purify water by using Arsiron Nilogon technology can be found in the attached document below: