Assam researchers develop low-cost filter to remove arsenic from drinking water

Researchers at Assam’s Tezpur University have developed and patented the filter that removes arsenic and iron from drinking water.

Residents of Mazgaon village in Assam’s Lakhimpur district could do little about the arsenic contaminated water they were forced to drink until a few years back. They found most water purifying machines expensive until they began using a low cost and easy-to-use filter – Arsiron Nilogon.

Researchers at Assam’s Tezpur University have developed and patented the filter that removes arsenic and iron from drinking water. It has been making a difference to the lives of thousands of people across the state by providing them access to clean drinking water they did not have until a few years back.

“Six big and small arsenic filters have been set up in our village and nearly 400 people are benefitting from them. Now we are not worried about consuming arsenic with our drinking water,” said Deeprupa Bhaktiari, a Mazgaon-resident

The Union science and technology department has acknowledged the method the filter uses. It has been published in national and international journals and was granted patent number 280737 last year.

High amounts of arsenic, a poisonous contaminant that can cause diseases like cancer, have been detected in Assam’s 29 of the 33 districts. The World Health Organisation (WHO) recommends a maximum of 10 ppb (part per billion) of arsenic in drinking water. A Tezpur University research found 990 ppb of the carcinogenic agent in a tubewell in Mazgaon.

“Concerned about the situation, we began our research in 2005 to find an easy and cheap solution that would benefit poor people in rural areas,” said Tezpur University professor Robin Kumar Dutta.

Dutta and his team tried finding a new method as several existing methods of removing arsenic like reverse osmosis were found to be ineffective for use in rural areas of developing countries due to high cost, use of electricity etc.

Dutta said a Japanese firm has approached them for exclusive rights to produce the filter commercially. “But as that would make the method costly and out of reach of poor people, who we want to benefit, we rejected the offer.”

Dutta’s team developed the filter in 2010, which involves treatment of contaminated water using small quantities of cooking soda, potassium permanganate and ferric chloride.

The results were impressive. The process was able to remove arsenic content from as high as 1,000 ppb to less than 2 ppb or to the undetectable levels.

“…(The filter) is very effective as, unlike other available methods, it does not use electricity and removes arsenic and other heavy metals at very lost cost,” said Manoranjan Nath of Tezpur-based North Eastern Regional Institute of Water and Land Management (NERIWLM).

NERIWLM did the third party technical evaluation of Arsiron Nilogon using various samples of groundwater with high arsenic content (between 500 ppb and 250 ppb). It found the filter was able to bring it down to single digits – below the WHO’s recommended levels.

Two 20 litre buckets – one for chemical treatment water and other to be used as a sand gravel filter – are needed to set up a filter unit at home along. A 500-litre unit costs ₹3,700.

For a household unit of 20 litres, one needs to add just 2 gm of cooking soda, nearly 6 drops of potassium permanganate and around 2 ml of ferric chloride. It would cost a user around ₹500 to filter 100,000 litres of water.

“We started taking field trials in 2010. The filter soon became popular and people asked us to set it up for them. Till date, we have set up over 100 filters across Assam, but many more are being set up by users themselves after getting training from us,” said Dutta.

A filter unit was set up in Uttar Pradesh’s Mirzapur two months ago.

“We have been using the filter to remove arsenic from our drinking water for our family of 24 members. Now many more people in the area want to get such units installed,” said Akhilesh Kumar, a school teacher in Mirzapur.