A Canadian team of researchers from the University of British Columbia (UBC) has devised a new method that can turn the fatbergs plaguing the sewers of many major cities into renewable biogas fuel.
Fatbergs – such as the famous one extracted from London’s Whitechapel district in 2017 – are congealed masses of fats, oils and grease (FOG) flushed into sewers which harden over time into massive blobs of grease and solid waste which can clog sewer pipes and cause overflows, wrote the Smithsonian magazine on 20 August.
But the UBC had now developed a technique that, according to the research team, could turn fatbergs into biofuel more efficiently than currently methods and work inside sewers, eliminating the laborious task of clearing the fatbergs out of the pipes.
“This method would help to recover and reuse waste cooking oil as a source of energy,” said Asha Srinivasan, an engineering researcher at the UBC who worked on the study.
In the new method, the FOG is heated to 90-110°C, after which hydrogen peroxide is added to break down organic matter and release fatty acids, which are finally broken down into methane gas using bacteria.
“Finding the right combination of microwave temperature and hydrogen peroxide dosage is the key to the success of the process. Our process helps break down FOG, making it easy for the bacteria to digest and produce more methane,” explained Srinivasan.
The method could be used by municipal water treatment programmes to destroy fatbergs, but could also be of use to farmers who treated farm waste in biogas digester, turning manure and other biological waste into biomethane.
The UBC method would allow farmers to increase the current ratio of 30% FOG to 70% manure and other waste to include up to 70% FOG, meaning they could recycle more oil waste and produce more methane.
However, Chad Jafvert, a professor of civil engineering at Purdue University, said that although the technology was a “clever idea”, its cost could be a hindrance for wider use as heating the FOG required a source of energy.
The UBC team was now running pilot tests at municipal sewage treatment plants and dairy farms to identify the optimum ratio of FOG to sludge of farm manure.
The researchers expected to have a full-scale system in place locally within the next two years, after which the technology could be easily adopted by other sewage treatment systems, reported Smithsonian.