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Professor’s DIY Filter Clears Toxic Metals From 100 Litres of Water For Just Rs 1

Dr Robin Dutta, a professor at Tezpur University in Assam, conceived a low-cost DIY water filter that uses baking soda, Potassium Permanganate and Ferric Chloride to clean water

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Arsenic, a naturally occurring material, has wide use in industries, such as glass, textiles, tanning and others. However, the element found in the earth’s crust has devastating effects on the human body.

The World Health Organisation (WHO) says that the presence of the element beyond permissible limits can lead to diabetes, skin diseases, heart ailments and even cancer. These are the same issues that residents living in the North-East state of Assam have been facing over the years.

Out of the 33 districts in Assam, 24 have reported contamination by arsenic in their groundwater sources.

Dr Robin Dutta, a professor at the Department of Chemical Sciences at Tezpur University in Assam, has witnessed the life-threatening effects of arsenic first-hand. “I have lost many friends and family members to cancer, and it took time for me to realise the reason behind their health ailments,” he tells The Better India.

Since 1975, he has witnessed about 30 people lose their lives to cancer in his village in Majuli. The pain and suffering of the people pushed Dr Robin to create a low-cost solution that is currently benefiting thousands.

Purifying water at 1 paisa/litre

Arsiron Niligon Dr Robin Dutta
Dr Robin Dutta with school students, explaining functioning of Arsiron Niligon.

Being a student of science, he conducted various tests to detect fluoride in water. “The worrying issue of fluoride and its ill-effects on the health of the residents was well-known. But it was by accident that I learned the gravity of the arsenic issue,” he says.

He adds, “I was trying to find a low-cost method for removal of fluoride when it was noticed by some during a research that the vast groundwater areas of Assam were contaminated with arsenic — a more serious issue.”

Dr Robin says that the issue came to light in the early 2000s, and he decided to find a solution for the same.

“The permissible limit for arsenic in water recommended by the WHO is 0.01 mg/litre. However, the amount was much higher, which resulted in health problems,” he adds.

Dr Robin started using his scientific knowledge to work on a low-cost solution. “The locals of the region still cannot afford expensive water filters that remove heavy contaminations to make drinking water safe. Hence, an alternative was required,” he says.

Over 10 years, Dr Robin developed a Do-It-Yourself (DIY) water filter — Arsiron Nilogon, that costs Rs 350 and makes water potable. The recurring cost of the water filter is 1 paisa per litre, which is now widely used by families across the state and has also reached other parts of India, the USA and Yemen.

Speaking about his research, Robin says that he identified three chemicals that could be easily accessed and were inexpensive — baking soda, potassium permanganate and ferric chloride.

“Baking soda is available in home kitchens, and the other two chemicals are available at fertiliser shops, science stores or online platforms,” he explains.

“Baking soda works to control the pH value of water and brings it to moderate levels. The recommended levels are between 6.5 and 8.5, and the baking soda achieves a 7.3 pH value. Moreover, it works to neutralise the acidic effects of ferric chloride that mixes with the water during the purification,” he says.

Dr Robin adds that potassium permanganate, when mixed with water, converts difficult-to-remove arsenic by oxidation. “Ferric chloride gives iron oxide coagulation, which absorbs arsenic and settles at the bottom. Solid manganese dioxide formed from potassium permanganate catalyses the conversion of complex arsenic into easily removable form,” he says.

He says that all a person needs to make the water filter is two 20 litre buckets, sand, gravel and three chemicals to remove arsenic, iron and all toxic metals to make water drinkable.

Dr Robin Dutta Arsiron Niligon
Residents install water filter ranging from 20 litres to 500 litres as per the need.

In one bucket, water is poured and mixed with chemicals. Meanwhile, the other bucket is filled with sand and gravel. The water is treated and is then poured into the sand-gravel filter, thus, making it safer to drink.

In 2010, when he presented the method to a government funding agency seeking grants for the research, the experts appreciated it and encouraged him to create a working model.

“I had no means to fund the field trial, but the jury insisted that I somehow manage to create a working model. I decided to take the step which gave better results than expected as it removed heavy metals like lead, chromium and others, including arsenic,” he notes.

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Dr Robin says that G J Samanthanan from the government department of science visited the field trial conducted by the professor, in two arsenic affected villages in Jorhat and coined the term ‘Arsiron Nilogon’, as he was impressed by its efficiency. “Arsiron is created from Arsenic and Iron., while Nilogon means separation in the Assamese language,” he says, adding that he is glad that an Assamese word is reaching different parts of the world through this water filter.

He says that, after feeling convinced, Dr Samathanam sanctioned funds to conduct national-level workshops and popularise this water filter.

A simple yet unique solution

“I started reaching out to the villagers, NGOs and schools, demonstrating the model. Residents were hesitant at the beginning considering the chemicals involved, but eventually accepted after some of them started using and realised the difference,” he says.

Dr Robin claims that his water filter model has reached all corners of the state, benefiting 3,000 families to date. “It is operational in private schools, NGOs and residents who also advocate its use to others,” he says.

Jiten Bora, the headmaster at Athkhelia Uran Pakhi Bhawan school, agrees that families there suffer many health issues, and the cost-effective technology has become popular among the masses for its multiple benefits. “We ask students to make the water filters as part of their science projects. The solution is simple yet unique,” he adds.

Jiten says that initially, the residents were sceptical about using chemicals, doubting that it would adversely affect their health. “But the awareness has helped people accept the useful technology,” he adds.

Pushpa Gogoi from Chairdeu district says that it has been three years since he and other village folk began using the water filter. “The taste of the water improved, and it became lighter and easier to digest. The odour and colour of the water also disappeared. The cases and severity of skin disease have also reduced, resulting in lesser trips to the doctors,” he adds.

Dr Robin’s work has support from government agencies such as UNICEF and an NGO called WaterAid.

Though a success, Robin says that he felt so passionate about helping people that he even resigned from the post of Head of the Chemical Sciences Department in 2009 to focus entirely on the water filter project. “I also fought corporates when they opposed my patent application but defended myself without any legal aid to get the patent granted,” he adds.

“I am glad that thousands of residents are benefiting from this simple model. They often make them for others on request,” he says.

Dr Robin continues to promote his model for free. “I do not sell or charge money for promoting the filter. It is the residents who should benefit through better health,” he says.

He shares a few tips on how to make your water filter:

Step 1: Fill one 20 litre bucket with water.
Step 2: For 20 litres, put 2 grams of baking soda, six drops of potassium permanganate or KMnO3 and 2 ml of ferric chloride successively with mild stirring occasionally.
Step 3: Leave the mix for at least one hour, allowing chemicals to complete the process and settle the arsenic in the solution, if any.

Step 4: Place 2-2.5 inches of washed gravel at the bottom in another bucket, and fit a tap.
Step 5: Place a clean cotton cloth over gravel and fill the remaining bucket with washed sand. The texture of the sand should be fine and not coarse.
Step 6: Once the water is ready, pour it in the bucket with sand and gravel to access it through the tap.

The filtration is a one-time process but will have to be repeated by mixing chemicals, as required, for another batch. One or two inches of sand at the top layer should be replaced on a half-yearly basis. The concentrated liquid sludge may remain in the sedimentation bucket for 10-12 days. This will need to be collected periodically in a sand filter made of an ordinary pot to remove the solid sludge and separate the arsenic-free water. The solid sludge will then be safely buried.

Edited by Yoshita Rao

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