Students make biodiesel from used vegetable oil

BENGALURU: What do you do with

vegetable oil

after use? Flush it down the drain? You could convert it into biodiesel, as PES University students have been doing for the past three years.

SH Kavitha, PhD student, department of

biotechnology

, has been converting used vegetable

oil

from different sources into biodiesel at the university’s lab, which is used to run 40 college buses as well as steam boilers at the boys’ hostel.

“When you fry something in edible oil, twice or more times, the oil becomes toxic and is not fit to consume. Most throw it away in the drain. This only adds to pollution. We wanted to put an end to this and began researching with waste vegetable oil in 2010,” Kavitha told TOI.

Initially, the researchers took waste oil used by fast-food giants for frying burger patties, French fries or chicken. “We converted it into biodiesel and tested its engine efficiency. The experiment was successful,” she added.

The university currently collects waste oil from houses of 250 staffers and converts it into biodiesel, said PES University registrar V Krishna Murthy.

Kavitha said the collected oil first goes through a two-stage filtration process to remove sediments and moisture, after which it is put through a technical procedure called trans-esterification, which yields biodiesel and glycerol. The product is then separated from water content, following which its efficiency is tested.

“We have a skid-mounted model at the lab, customised to produce biodiesel and glycerol. In our buses, we mix 25% of this biodiesel with commercial diesel. Anybody can give us their used or waste vegetable oil. In a day, we can produce 100 litres of biodiesel, which is smoke-free,” added Krishna Murthy.