Biotech students design model to desalinate RO-reject water

Chennai: In a first of its kind, a group of biotechnology students at the Indian Institute of Technology Madras (IIT-M) have designed a model to purify water rejected from domestic Reverse Osmosis (RO) water purifiers. The model, if formulated, can conserve a huge amount of water on a large scale, as the reject water from purifiers constitutes 50 to 80 per cent of the original volume.

The model is conceptualised from microbial desalination technique through which the saline content in rejected water is removed by generating electricity. Students have formulated their own microbial desalination cell to develop the model at less than Rs 20,000. The application needs to be attached to RO purifiers to carry out the process. The IIT’s entrepreneurship panel - Nirmaan, funded the project while the college provided the lab space and equipment.

About 97 per cent of the salt content can be removed through the process, said the students who are testing for more accuracy. Technically, the handy model has three chambers – a positively charged electrode (anode) where wastewater from the kitchen is filled; RO-reject water at the second and negative electrode (cathode) with an electron acceptor at the third.
One of the students working on the project, Anjani Sreeprada Chakrala told DC that wastewater from kitchen should be used in the first chamber as they are rich in organics. “It is important for the anodes to feed on the organics to generate electricity,” she said.

“If the idea of using the kitchen waste does not go well, a chemical called sodium acetate can serve as an alternative,” said Sreeprada. By connecting the positive ions and the negative ions, electricity is generated, which removes the salt ions in the reject water, said Srihita Rudraraju, who is also a part of the project. “We thank our professor, T.S. Chandra for helping us with the concept. Water crisis can be dealt technologically through reusing the reject. The major task now is to reach out to the people for the same,” one of the student said.