It is a cheap and eco-friendly way of purifying water. And it will also open up a new market for corn cobs that are usually discarded as bio-waste.
MOUNTAIN VIEW, US: A student of 9th standard of the state of Odisha, India, Lalita Prasida Sripada Srisai has won an award at the Google Science Fair, in California. Winning the ‘Community Impact Award’ the 13-year-old from DPS Damanjodi school in Koraput district of Odisha, developed a low cost bio-absorbent based water purifier, which functions mainly on waste corn cobs.
She won in the 13-15 years age group and received $10,000 as the prize money. Additionally, she will also be supported by the organization for a year to build upon her project.
Her basic idea was to purify water using the least utilised part of the maize plant – that is the corn cob. An important agricultural waste, corn cob is a suitable absorbent because of its high mechanical strength, rigidly and porosity.
“Hence, contaminants like oxides of salts, detergents, suspended particles, coloured dyes, oil and grease get adsorbed in the surface of the corn cobs. Some of the heavy metals are also adsorbed by corn cobs. If the drain pipe of the household is connected to a chamber having different layers of corn cobs in partition layers or to an S-trap pipe having corn cobs, it will separate about more than 70-80 percent of contaminants including suspended particles from the waste water,” said the project report on the Google Science Fair website.
It is a cheap and eco-friendly way of purifying water. And it will also open up a new market for corn cobs that are usually discarded as bio-waste.
For the experiment, Lalita collected the cobs from the nearby farm and sun dried them for a month. The pith of one cob was removed to make a hole at the centre of it, in which 50 ml of domestic effluent collected from a kitchen drain pipe, was poured. This was allowed to pass through the hole and the collected filtrate was then tested for purity.
After this pilot stage, water with several added chemical impurities was passed through five bottles, each containing a different layer for purification. These layers included long pieces of corn cobs, small pieces of corn cobs, powdered corn cobs, activated charcoal made from corn cobs and fine sand.
It was observed that most of the coloured substances present in the water were adsorbed in the charcoal layer. The suspended particles were absorbed in the chaff layers of both long and small pieces of corn cobs. And gasoline waste was absorbed in the powdered corn cob layer. According to her teacher, Pallabi Mahapatro, the technique can be used for immobilising the contaminants in domestic and industrial effluents, and in ponds, reservoirs and water tanks.
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