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Wednesday 19 August 2020 2:23pm

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Dr Risha Nathan has found an innovative use for food peels.

Some people turn their fruit and vege peels into compost. Some turn them into garbage. But new University of Otago PhD graduate Dr Risha Jasmine Nathan has spent the last three and a half years learning how to turn those peels into purifiers.

Her research has focused on how such simple substances can be transformed from waste products into cheap, efficient and easily available water filters for low-income populations in need of cleaner drinking water.

A student of Otago's Department of Pharmacology and Toxicology, part of the School of Biomedical Sciences, Dr Nathan says she first discovered the concept of peels becoming purifiers during her Masters dissertation research, in her native country India. She had been working on the analysis of heavy metals in commercial hair dye samples, and drinking water collected from refugee camps in India.

“I came across the technique of removing heavy metals from water using agricultural wastes. After having a preliminary discussion with a colleague, I performed studies with unmodified banana peel in water containing lead, and got amazing results.”

“Such methods of decontamination of drinking water are very much needed in the present world, especially in the developing countries. Water filters could be made from waste agricultural products, which are otherwise dumped in landfills, causing land pollution."

She published those results and from there decided to “go deeper in the biosorption field” for her PhD research.

Born in Prayagraj, Uttar Pradesh in North India, Dr Nathan graduated with honours in chemistry from the Banaras Hindu University in Varanasi, Uttar Pradesh in 2010. She gained her Masters in Forensic Science with specialisation in Forensic Chemistry and Toxicology from LNJN National Institute of Criminology and Forensic Science in New Delhi. For the next step in her academic career she wanted to head offshore, she says.

“I was looking for an internationally recognised university for PhD research, one that would allow me to conduct quality research in a relatively short period of time.

“I eventually decided to come to New Zealand as the country has a reputation for their awareness and efforts towards maintaining high environmental standards.”

The University of Otago got in touch early, she says.

“I had contacted Professor Rhonda Rosengren, the former Head of the Pharmacology and Toxicology Department, with my research proposal, and she was very interested. She applied for the School of Medical Sciences Dean's Bequest Fund and in no time we got that for our project.”

Paying for her PhD was her next quandary, but that too was quickly resolved. She was awarded the University of Otago Doctoral Scholarship for three years, which paid her tuition fees and living expenses.

“And for that I'm very grateful to the University of Otago.”

She also received travel grants, allowing her to attend international conferences to present and publish her research.

“The realisation of how big this could get came from the response of Otago Innovation, which helps University of Otago researchers commercialise their research. She applied for funding to develop a domestic water filter system to remove heavy metals from drinking water and, although the project ultimately didn't qualify for funding, the impact the research could have was “quite clear”.

“From that point on, we changed the course of the research from complicated laboratory experiments to exploring the potential of fruit and vegetable peels to remove heavy metals from real world drinking water.

“We started seeing things from a practical angle rather than only going the theoretical way.”

Her biosorption technique involves the peels from apples, bananas, cucumbers, kiwifruits, oranges and potatoes. The peels are immobilised into beads using sodium alginate, that makes them more efficient as biosorbents.

The beads are then used for the simultaneous removal of arsenic, cadmium, chromium, copper, mercury, lead and nickel from a cocktail solution. It is a low-cost solution to a serious problem, and finds a fantastic use for existing waste products.

“Such methods of decontamination of drinking water are very much needed in the present world, especially in the developing countries. Water filters could be made from waste agricultural products, which are otherwise dumped in landfills, causing land pollution.

“I consider myself very privileged to be a part of this revolutionary water decontamination technique. It has immense potential to replace the existing expensive methods, that also generate toxic sludge that is released in the environment post-treatment.”

For now, though, the next part of her journey will take place in India, where she is returning later this month. While her career could go in multiple directions, she insists “research and publications will certainly be a part of it”.

So too will her memories of her time in New Zealand.

“It has been a wonderful experience living here for the last three and a half years. I've learnt so much.

“I'll miss travelling to the beautiful tourist places here and driving through the breath-taking scenery. I'll miss my residents that I took care of in my part-time job as a caregiver, and the whole experience of it.

“And I'll miss being a University of Otago student from here on, the wee lunch and coffee breaks with friends, shopping on a budget and the weekend get-togethers. Alas, it's time to move on!”

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