Lalita Praside Sripada Srisai has lived in many regions of India in her thirteen years. She found agricultural regions the most inspiring for their ability to live in harmony with their surroundings. After talking to one tribal farmer Lalita learned that corn cobs had very little use as an agricultural waste product. Corn cobs are cheap, plentiful and easy to handle.
She worked to find an efficient way to use the waste product and built her idea around the hypothesis that the cobs would be able to filter water due to their porosity. Her project, Low Cost Bio-Adsorbent, won the 2015 Google Science Fair Community Impact Award.
Srisai took corn cobs from local farmers and dried them in the sun for one month. Full cobs, cobs cut into pieces, cobs burned into charcoal, cobs crushed into powder and fine sand were each used as a filter level for waste water.
Using several different materials to clean the water proved to be successful. Most of the dyes in the water were adsorbed in the charcoal layers, where suspended particles filtered out through the long and short cob layers. Gasoline waste was found mostly in the powdered cob layer. Tests were done for calcium salts, magnesium salts, detergents, oils, grease, dyes and suspended solid particles from domestic waste water. Industrial water was tested for copper, lead, strontium, chromium, dyes, gasoline wastes and total suspended solids. All of the test elements were removed or lessened after the filtration process but the report does not discuss percentages or hard numbers.
This is a great project that can be used on both small and large scales to effectively remove some if not all waste products from industrial and residential waters in India. There is no mention of what happened to the cobs after the experiment or how toxic they are.