An analysis of small grey balls that washed up on Sydney’s Northern Beaches earlier this month found they were largely made of soap scum and cosmetics.
Nine Sydney beaches, including Dee Why, Manly and North Narrabeen, were closed on January 14 after debris appeared on the shoreline.
Chemistry professor Jon Beves from the University of New South Wales said the marble-sized balls were mostly made up of saturated fatty acids and calcium.
“We analysed these and found that they’re mostly saturated fatty acids and calcium, so the fatty acids that you’d find in cleaning products or cosmetics, soaps,” Professor Beves said.
Other small items, including pharmaceuticals and traces of animal faecal biomarkers, were also found in the balls, according to Professor Beves.
In October, some of Sydney’s most popular beaches, inlcuding Coogee Beach, were closed when black balls mysteriously washed up along the shoreline.
Scientists found they were “disgusting” lumps of human faeces, drugs, cooking oils, fuel and PFAS chemicals.
Professor Beves said the balls found at Coogee were different to the ones found earlier this month.
“The ones that we found down at Coogee, they were majority, what looks like cooking oil and the similar sort of fatty acids that we found here, but there were all other things in them as well,” he said.
“I guess what looked like diesel, which is why they were black. These ones on the North Shore are much simpler composition than the ones we found.”
Grey balls made of ‘hydrophobic’ materials
He said the balls found at Sydney’s Northern Beaches were “hydrophobic” materials commonly washed down the drain at home.
“The reason that these things sort of clump together is because everything that’s in there, all the different compounds that are in there, are what’s called hydrophobic,” he said.
“They don’t really like water, so they’re just trying to get away from it.
“And when they find other compounds that also don’t like water, they stick together sort of like glue and this is why they end up being in these sort of lumps, and they form commonly in sewers.”
Authorities initially feared these balls could be made of toxic tar. Further testing from scientists indicated they are closer to ‘fatbergs’ typically found in sewers.
In a statement, Sydney Water said it was working with the NSW Environmental Protection Authority (EPA) to investigate the possible causes of the balls.
It said there were no issues reported with the operations of Warriewood or North Head Water Resource Recovery plants before the debris appeared on Northern Beaches.
“We comply with our licences as set by the NSW Environment Protection Authority,” Sydney Water said.
“Sydney Water has developed a long-term capital operating plan, which will see over $30 billion invested in the next 10 years to upgrade and expand our water and wastewater networks.”
The EPA has been contacted for comment.