Saluting The Teen Who Built A Low-cost Water Purifier Out of Corn Cobs

Lalita Prasida Sripada Srisai is a young woman from the developing state of Odisha, India, who at 13 years old, developed a low-cost water purifier that operates on corn cobs. Her innovative creation, geared towards addressing the water contamination problem in her locality, won her the Community Impact Award at the 2015 Google Science Fair. The award honors “a project that makes a practical difference in his or her community by addressing an environmental, health or resources challenge.”

Four years later, Srisai’s name and her accomplishments have seemingly disappeared from the spotlight. Today, we highlight her achievement once more to commemorate this teenager’s invention that put an agricultural waste product into good use.

Examining The Available Water Resources

The fact that water is crucial to the survival of the human race, as well as of the other living creatures, cannot be stressed enough. Unfortunately, because of the abundance of clean water in developed countries, it seems to have been taken for granted. Other parts of the world, however, are not so lucky and are continuously faced with the challenge of day-to-day life without reliable access to potable water.

Developing countries, especially, have minimal resources that provide them with sufficient amounts of safe drinking water. Though some areas do provide tap water, this is often unsafe due to the presence of various contaminants including toxic chemicals, microbes, sediment, and suspended organic material.

The one thing that both developed and developing countries have in common is pollution. A variety of factors have led to an exponential increase in pollution over the decades — industrialization, agrichemical methods, deforestation, consumerism, and oil drilling. These practices have transformed a significant number of the planet’s natural water resources into a melting pot of waste and toxins.

Water is subjected to several treatment processes to rid it of pollutants. Many involve chemicals which can also be quite hazardous (e.g., disinfectants and heavy metals). Water distribution systems can also introduce other substances, including lead and rust. Ingesting too much of these substances can lead to several health problems.

Hope In The Corn Cob

Srisai’s water purifier can change the status quo. Her invention makes use of a highly abundant resource widely considered as agricultural waste and used primarily as a fuel for burning. The corn cob is easily accessible at little cost, making it a sustainable alternative for water purification.

In terms of efficacy, the corn cob is a bio-adsorbent material that can effectively filter the many contaminants present in water. This is attributed mainly to the corn cob’s mechanical strength, rigidity, and porous nature.

The filtration system is founded on the scientific principle of adsorption (not to be confused with absorption). In adsorption, contaminants are captured on the surface of a material (in this case, the corn cob), which cleanses the water of pollutants. With this, the corn cob becomes a useful tool in the purification of domestic wastewater.

Srisai’s water filtration system involves corn cob in varying degrees of refinement. After the cobs were left to dry under the sun for an entire month, some were cut, others ground into powder, and the rest burned to create activated charcoal. Each of these was separated into different levels, of which there are five in total.

This filtration system was tested by letting untreated water pass through the various layers. This simple process was able to remove at least 70% of the contaminants. It was also found that different layers trapped different types of pollutants.

• Large pieces of corn cob - This layer trapped particles large enough to be visible to the naked eye.
• Small pieces of corn cob - These cobs were cut into one-inch pieces. This layer captured smaller suspended particles.
• Powdered corn cobs - The granulated cobs in this layer were able to adsorb most of the gasoline waste.
• Activated charcoal made from corn cob - The layer of activated charcoal adsorbed contaminants like colored dyes and lead.
• Fine sand - The remaining contaminants, both organic and inorganic toxins, were trapped in the layer of fine sand.

A report published in the Google Science Fair website stated, “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 more than 70-80 % of contaminants including suspended particles from the wastewater.”

According to Pallabi Mahapatro, Srisai’s teacher, using this technique, ponds, reservoirs, and water tanks can be cleansed of contaminants in both domestic and industrial effluents.

Inspiration Leads To Motivation

Srisai grew up in the backwaters of Odisha, an agricultural region in India. One of her joys was to visit different villages to observe their lifestyles. On those journeys, she noticed the discarded heaps of corn cob that were left on the side of the road — unwanted refuse that even the animals wouldn't eat. This sparked the idea of transforming this farm waste into something useful for her village.

“Villagers’ lifestyle revolve around agriculture, in cultivating many varieties of crops,” Srisai says in an interview with NDTV. “This developed an interest in me to focus on science and develop something new, related to agriculture.”

Her first experiment involved placing shriveled corn cobs into a bowl of grey water and leaving it there to soak. When she returned to it, it seemed as if the water had become cleaner.

At 11 years old, she began collecting corn cobs — from the kitchen, the side of the road, and local farmers. She built a prototype filtering system in her own home and tested it in her school’s chemistry lab. Further testing needs to be done before the project is complete. However, with the idea of this economical alternative to water filtration, areas that have little to no access to clean potable water one day will.

Srisai’s project won the Community Impact Award at the science fair. As part of the award, she received the support of Google, a yearlong mentorship from Scientific American, and a $10,000 grant to fund the development of her project.

While the world holds its collective breath to see if this invention can be mass produced, there are a variety of affordable options currently available in the market. Efilters can offer you quality water filtration systems that can effectively remove contaminants and provide safe drinking water for your home or office.