Veggie might: Meet the scientist using peels to purify water

Risha Jasmine Nathan, 34, could have been a doctor like her mother wanted. She certainly had the aptitude for it. She completed her undergraduate degree in chemistry with honours, and was a medallist in her Master’s programme. But Nathan is certain she would have been a terrible doctor.

“Interacting with people is not my forte,” she says. “I am better off working quietly in a lab, with my chemicals and dead bodies.”

Still, her mother, an associate professor of zoology at a college affiliated with the Allahabad University in Prayagraj, is proud. Nathan became the next best thing: a forensic scientist. Her PhD research involves testing the ability of fruit and vegetable peel to remove heavy metals from water. It addresses two crucial problems – of food waste and water contamination.

The research got her onto the 50 Next Class of 2022, a list of game changers in gastronomy. This is the second annual list drawn up by 50 Best, the organisation that compiles The World’s 50 Best Restaurants and the World’s 50 Best Bars lists. Nathan is one of four Indians on it this year, in the Science Innovators category.

“Dr Risha Jasmine Nathan is on track to invent a new, sustainable solution to the problem of water contamination,” reads the citation by 50 Next. It adds that her “ground-breaking technique has been recognised as potentially gamechanging in developing countries, where the removal of contaminants such as heavy metals from water supply is a big issue demanding affordable solutions.”

The numbers for India alone are staggering. The UN Food and Agriculture Organization (FAO) estimates that about 40% of the food produced in India is wasted. India’s Ministry of Food Processing Industries puts fruit and vegetable losses at 12 and 21 million tonnes respectively.

The idea of using peels to purify water struck Nathan while she was studying for her Masters at the LNJN National Institute of Criminology and Forensic Science in Delhi. A love for analytical chemistry got her interested in the subject. In her final year, she did two projects, one where she tested the presence of heavy metals in hair dyes.

While working on the heavy-metals project, a classmate and she came upon research that had been underway for several years. They found that scientists were using banana peels and other agricultural waste to remove heavy metal ions from water. “How brilliant an idea is that!” she says.

They ran some experiments to test the process themselves. “That was a breakthrough moment in my research journey,” Nathan says. She published a paper on her findings, then applied to a PhD programme at the University of Otago in New Zealand. They loved her thesis idea, and invited her to work on it for three years there.

Nathan tested six different vegetable and fruit peels (apple, banana, orange, cucumber, kiwi and potato) for how well they could attract arsenic, cadmium, copper, mercury, lead, nickel and chromium from drinking water. The peels were oven-dried, pulverized to very fine particles, then combined with alginate, a chemical derived from brown seaweed, and made into small beads that could be dropped into water. The idea was to get the negatively charged functional groups on the surface of the beads, such as carboxyls and hydroxyls, to bind with the positively charged heavy-metal ions, in a process called biosorption.

Over three years, Nathan published six papers on her research, detailing the ability of the peels to attract heavy metals. She also treated her department to a lot of fruit and potatoes.

“Risha was the most successful PhD student I have ever had,” says Ronda Rosengren, professor of pharmacology and toxicology at the University of Otago, and Nathan’s PhD supervisor. “She has published more papers in her three years than any of my previous 20 PhD students. The other unique thing was that all the data in all her papers was generated by her alone.”

Nathan says she would love for her work to be taken forward commercially. “With more research, we can come up with highly charged beads in small packages that can be put into home water filters, or used at large purification plants. Particularly in rural areas, the beads could just be dropped into water containers.”

Nathan recently began working as a lecturer in forensic chemistry at Anglia Ruskin University in Cambridge. She’s got much left to do, she says.

“I don’t want to have to be put in a box, where there is only one area I am working in,” she says. “This idea came to me while I was doing my Master’s. In the future, if I get the opportunity, I would love to continue working with heavy metals, environmental toxicology and biosorption.”

She’s always been that way, she says, confident, self-assured, and a hard worker. In New Zealand, she worked three part-time jobs, even though she was there on full scholarship. “I wanted to keep busy. I always want to do something.”

She plays badminton and swims, is an active member of the church, sings, plays the guitar and keyboards, and loves to sketch and paint. She also travels extensively with her husband, whom she married in October.

“I’m still settling in here, but I am excited for what comes next,” she says.

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