For pure water

By Tom Kendall
Published: Tuesday 30 September 2008

Down to Earth
Down to Earth
large amounts of distilled water are needed in research labs. But the production process requires a continuous flow of water. Faced with growing water wastage in their lab, Munnalal, Sitaram and Jagat, a group of lab assistants at the Banaras Hindu University, have come up with an ingenious solution for distillation. Instead of allowing water to pass straight from the tap, through the cooling unit and back down the plug hole, as in the typical set-up, the trio used a pump, a plastic tank, some tubing and a showerhead and now save at least 750 litres a day. This becomes significant considering that use of distillation process also used extensively in industrial processes.

S C Lakhotia of the Zoology department, whose assistants came up with the idea, is excited about the technology. "A typical distillation plant requires 800-1,000 litres of tap water for every 10 litres of distilled water it produces," he explains."Given the universal requirement, a simple and economic device like this can save millions of gallons of precious water every day." At less than Rs 1,000 to implement, the device is certainly economic. While the components are all available locally, Lakhotia asserts there is plenty of room for improvization. As for simple implementation, he explains the key to success is allowing a 12 inch-drop from the showerhead to the tank.

This allows the water, heated from the process, to cool slightly before it is re-circulated. For extensive cooling, water is left to circulate for about five hours at the end of each day, after the main distillation unit is switched off.

"Our main concern was humidity and therefore loss to evaporation from the tank. But we have been using the apparatus for three months now and even in humidity of 80 per cent the device has worked well," he says. The team clean the tank once a week to remove calcination, algae and other deposits left by the water but otherwise there have been no problems.

On water circulation and whether the pump provides a continuous flow, Lakhotia said that having installed flow valves to prevent against overloading, the system works well and the pump ensures a reliable, continuous supply. According to N Raghuram of Indraprastha University's School of Biotechnology in Delhi, "What is exemplary about this is the spirit of innovation and conservation," he said. He suggests that a centralized solar water distillation unit coupled to a recyclable coolant system should be designed.

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