An Indian renewable fuels company is examining the opportunities of turning the waste oils and fats leaking from the broken sewage systems of the city of Bengaluru into biodiesel.

The Bangalore Water Supply & Sewerage Board (BWSSB) has authorised Eco Green Fuels (EGF), a private firm producing biofuels from used cooking oil and lubricant waste, to launch a pilot project that seeks to process fat waste in the city’s sewage into biodiesel feedstock, India’s The Economic Times reported on 17 January.

BWSSB said its sewage treatment plants were unable to remove the oils and fats entering the sewage system, which accumulated in treated water and finally ended up in Bellandur Lake, where it could take up to 70 years to degrade.

“Because there is a lot of unmanageable waste – about 100,00kg of fat is discharged into the sewage system every day – we thought why not convert this waste into high-value green energy,” Julesh Bantia, founder of EGF, told The Economic Times.

Bantia said EGF had now collected the first sewage samples from Bellandur Lake and, in consultation with scientists backing the project, was in the process of extracting pure fat from them for conversion into biodiesel feedstock.

Issues with the availability of used cooking oil for biodiesel production had led the company to explore this more unconventional feedstock source.

“The idea behind this is that any substance in fat form is a potential feedstock for biodiesel manufacture. The biggest challenge in the process has been to identify the resource and pre-treat it,” said Bantia.

The pilot project had the backing of both BWSSB and the Karnataka State Biofuel Development Board, although both organisations also identified possible stumbling blocks.

Satish N, BWSSB chief engineer, said the board was keen to back initiatives to reduce waste inflows to sewage treatment plants, but he was unsure how much fat could be extracted from the sewage.

“The fat may not be available in a large quantity,” he said. “It varies from place to place. A sewer line flowing close to a milk and dairy unit may have a high fat content, but this may not be the same at all places.”