Scientists solve a puzzle: What's really in a fatberg

Part of a fatberg in the town of Sidmouth, England, in February. Photo / AP

When a giant fatberg was discovered in the sewer of a small coastal town in southwestern England last year, the company that manages the pipes was so mystified by the greasy mass of solidified fats and waste materials that it enlisted the help of scientists to discover what it was made of.

The grisly results of an autopsy were made public Friday, and they were not pretty, but held some surprises. Stuck within the massive, stomach-churning lump were wet wipes, as expected; oils; sanitary products; and even a set of false teeth.

Fatbergs are more commonly associated with large cities such as London and New York. Their contents can become a taxonomy of the habits of the inhabitants of nearby towns or cities.

When a 140-ton fatberg was found in the East End of London in 2017, a subsequent autopsy revealed that the city's residents had been flushing condoms, syringes and narcotics — including cocaine and ketamine — down the toilet, and they were all lodged inside it.

But how a 64 metre long fatberg could have festered for years underneath the picturesque seaside town of Sidmouth, England, more than 250km from London, presented a different puzzle to the company that manages the sewers in the area. Sidmouth, which counts only around 13,000 people as permanent residents, was not considered a prime fatberg target.

So before all trace of the fatty mass was destroyed, South West Water, the company that manages the sewers in Sidmouth and across 4,300 square miles of England, demanded answers.

Four 10kg lumps were taken from the beastly blockage and dispatched to scientists at the University of Exeter nearby for analysis.

"We wanted to learn as much as we could about it, how it was created and what it was made of," Andrew Roantree, South West Water's director of wastewater, said in a statement.

A team of 10 scientists welcomed the unusual challenge and carried out a dissection that involved melting down some parts of the fatberg, extracting and identifying the waste materials and even performing DNA sequencing.

The study was fascinating, John Love, a professor of synthetic biology at the University of Exeter and the project's leader, said in an interview Friday. But his team did not embrace all parts of the autopsy.

"It was my first time analysing a fatberg, and when you smell it, you think this is going to be the last time because the smell was honking," Love said. "It was awful to do, it smelled gross."

He explained that he and his colleagues wore stab-proof gloves and steel-capped shoes to protect themselves from any potential dangers within the samples. But after weeks analysing Sidmouth's fatberg, the scientists realised they had nothing to fear.

The results found no dangerous bacteria or chemicals in the lumps, which were composed of domestic waste glued together by fats used in home cooking.

Samples taken from a fatberg, during scientific analysis conducted by at the University of Exeter. Photo / AP

"We were all rather surprised to find that this Sidmouth fatberg was simply a lump of fat aggregated with wet wipes, sanitary towels and other household products that really should be put in the bin and not down the toilet," Love said in the statement.

But, the experts discovered, just as the analysis of London's fatberg revealed some of its residents' illicit habits, the contents of Sidmouth's fatberg hinted at the town's population — or more accurately, the kind of things they threw away or lost.

A set of false teeth was found within it. So, too, were a number of incontinence pads.

"Sidmouth is a small coastal community that is largely populated by retired people, so in a sense that explains it," Love said. "This is not a hotbed of crime and drug-taking or anything like that," he added.

London's Whitechapel fatberg was declared the biggest example in British history, and a piece taken from the 250 metre long mass was put on display at the Museum of London last year.

The exhibition captured the imagination of the public, bumping up visitor numbers, and the museum acquired the remaining parts for its permanent collection, even setting up a live-stream video of a piece of a yellowing fatty lump.

The fatberg in a sewer beneath Sidmouth, England. Photo / AP

Sidmouth's example, although it pales in comparison to its London equivalent, was the largest discovered in the service history of South West Water. A routine check in its sewers before Christmas last year revealed the fatberg longer than the Tower of Pisa lurking underneath the town's seafront road known as the Esplanade.

Dismantling the lump was a huge operation: It took workers eight weeks to excavate 36 tanker loads — each 3,000 gallons — of debris from the site, and it cost the business around 100,000 pounds (about $195,000.)

Despite the efforts made to banish the monster fatberg earlier this year, within the last few weeks, South West Water has revisited the sewer and noticed another one starting to form.

The size is nowhere near that of the fatberg discovered last year, Roantree said Friday, adding hastily that officials would clear it away to make sure it does not grow any larger.

Written by: Anna Schaverien

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