Sydney’s unusual sewerage system to blame for faecal and fat balls on beaches

Sydney’s unusual sewerage system to blame for faecal and fat balls on beaches, experts claim

This article is more than 2 months old

City invented Australia’s beach culture, environmentalist Richard Gosden says, but all this time ‘it’s been conducted in diluted sewage’

It’s the height of summer in Sydney, a time when tourists and locals are usually flocking to the city’s famous beaches.

But nine beaches were shut to the public this week – including well-known Manly – after more ball-shaped debris washed ashore.

Similar sticky round globules have been found on many of the city’s beaches over the past six months, forcing some of them to close temporarily.

The New South Wales environment minister, Penny Sharpe, has said the balls remain a “genuine mystery”.

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Coogee beach suspected oil slick: beachgoers warned after black balls wash ashore – video

But there’s a growing number of experts and observers who believe Sydney’s unusual sewerage system is to blame.

“We know it’s a sewage source,” says the water policy expert Prof Stuart Khan. “The combination of different chemical contaminants, human hair, is a very strong indicator that sewage is ultimately the source.”

In October last year, thousands of black balls washed up on several eastern suburbs beaches including Bondi, Bronte, Coogee and Tamarama.

Those balls were initially widely reported to be “tar balls” comprising crude oil until testing coordinated with the Environment Protection Authority (EPA) revealed they were consistent with human-generated waste.

While the EPA says it hasn’t been able to identify the source of the balls, Khan suspects they are from sewage discharged through outfall pipes or washed offshore with stormwater after heavy rain.

Khan, who heads the school of civil engineering at the University of Sydney, says Australia’s biggest city is “out of step” with the rest of the country when it comes to the way it handles sewage.

Unidentified white and grey balls on Dee Why beach in Sydney, Australia
Ball-shaped debris washes up at Sydney’s Bondi, Coogee, Maroubra and Cronulla beaches
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Sydney’s sewage is only given “primary” treatment at the wastewater plants in Bondi, Malabar and North Head before it is flushed out to sea through “deepwater outfall” pipes that reach between 2km and 4km off the coast.

Those pipes were built in the 1990s. At the time, Khan says, bureaucrats dealing with water pollution had “two main options” – upgrading the treatment process, or maintaining the level of treatment but building the longer outfall.

“We didn’t go the treatment route mostly because of the differences in cost,” Khan says. “That was seen as the less attractive option.”

Primary treatment involves physical processes such as pumping sewage through a screen to remove solid waste. Secondary treatment – not used at the Bondi, Malabar and North Head plants – involves finer filtration and biological processing to break down the sewage.

Sydney Water says its water treatment plants are operating normally. It is also investigating potential illegal dumping into the wastewater network or stormwater system.

The agency says it has developed a “long-term” plan to upgrade Sydney’s wastewater networks with $30bn over the next 10 years.

Khan says it’s a “reasonable theory” that the balls are formed from waste coming from the outfall pipes, but he doesn’t suspect anyone of “hiding anything”.

The environmentalists Dr Richard Gosden and Prof Sharon Beder take a different view – Gosden accuses the EPA and Sydney Water of knowing “exactly what’s happening”.

Gosden and Beder were part of a group called Stop the Ocean Pollution (Stop) who campaigned in the 1980s to have “secondary” treatment added to the Bondi, Malabar and North Head plants before the outfall pipes were built.

Stop garnered significant support, including from the 250,000 people who Gosden said attended the Turn Back the Tide protest concert in Bondi in 1989, but ultimately were unsuccessful.

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“Sydney invented beach culture,” Gosden says. “It’s Australia’s single cultural invention that’s been properly exported. And all the time, it’s been conducted in diluted sewage.”

Beder wrote her PhD on the history of the engineering of Sydney’s sewerage system. As part of it, she examined the link between the city’s sewage and ocean pollution. In 1989, she published a book about her research and said she presented her findings to the relevant government authorities.

“They denied the whole lot,” she says. “As they’re in denial now about these so-called mystery balls.”

Beder says the government needs to step up and improve sewage treatment and better police the “toxic” manufacturing waste she says is put into the sewers by heavy industries.

“The government is just unwilling to do what is necessary to clean up the waste,” she says. “It’s obviously from the sewers. That’s where the faecal matter and the oils and the grease and all the stuff that’s in these balls are.”

The balls have all been slightly different, depending on the beach where they’ve been found.

Dee Why was one of nine northern beaches shut after ball-shaped debris washed ashore. Photograph: Brook Mitchell/Getty Images
Balls found on the northern beaches were described as white and grey and ‘marble-sized’. Photograph: Brook Mitchell/Getty Images

Green, grey and black balls washed up in Kurnell, in Sydney’s south, in early December. The ones found on the northern beaches this week were described as white and grey and “marble-sized”.

A few balls were found at Bondi, Coogee, Maroubra and Cronulla beaches last weekend, the government said. Most of them were only the size of a pea.

Dr Sharon Hook, a CSIRO principal research scientist, says it’s too soon to say where the debris is coming from or to blame Sydney Water.

“They seem to be somehow related to sewage, because they have so much human-derived waste in them,” she says.

Hook says the balls would have formed when fats and oils and other materials that don’t mix well with water are added to sea water. Where they wash up depends on the currents.

Hook says people shouldn’t touch them and they should avoid beaches that are closed.

“I don’t know what it is, but it could be illegal dumping,” she says. “It would be the equivalent of walking through a crime scene.”

The EPA and Sharpe were contacted for comment.

Sydney’s archaic sewerage system a ‘significant’ source of microplastic pollution into the sea

This article is more than 1 month old

Malabar wastewater plant discharges 5.4bn to 120bn microplastic particles each day, CSIRO report says, prompting calls for more advanced treatment processes

It is not just human waste that is being pumped into the ocean off Sydney’s popular beaches due to the city’s unusual and archaic sewerage system – government scientists have confirmed billions of microplastics are also polluting the water.

A CSIRO report, released in 2020 but not reported on until now, found the wastewater treatment plant (WWTP) at Malabar discharged an estimated 5.4bn to 120bn microplastic particles into the ocean each day.

By comparison, the report found the Cronulla plant – which uses more advanced techniques to treat wastewater – discharged an estimated 86m to 350m microplastic particles each day.

Guardian Australia has previously reported that Sydney Water planned to spend $32bn to improve the city’s sewerage system but would not upgrade the Malabar, Bondi and North Head treatment plants.

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Coogee beach suspected oil slick: beachgoers warned after black balls wash ashore – video

Instead, the water authority planned to send less waste through the three coastal plants once it overhauls the rest of the city’s water infrastructure over the next 15 years.

Some experts believe the treatment plants may be to blame for thousands of debris balls or “fatbergs” that have washed ashore over the past six months.

The New South Wales Environment Protection Authority (EPA) has said testing revealed the balls were consistent with human-generated waste such as grease and faecal matter.

The CSIRO report also identified Sydney’s wastewater treatment plants as a “significant” source of microplastic pollution in the ocean.

The report noted there was “increasing evidence” the ingestion of microplastics – any type of plastic less than 5mm in length – could cause “physical damage” to marine life.

Sydney’s sewage is only given “primary” treatment at the wastewater plants in Malabar, Bondi and North Head before it is pumped out to sea through “deepwater outfall” pipes that reach between 2km and 4km off the coast.

Environmentalists unsuccessfully campaigned to have “secondary” treatment added to the plants before the ocean outfall pipes were built in the 1990s.

Primary treatment involves physical processes such as pumping sewage through a screen to remove solid waste. Secondary treatment involves finer filtration and biological processing to break down the sewage.

Tertiary treatment – which is used at the Cronulla plant – involves further filtration as well as biological treatment and UV disinfectant before the effluent is released.

The CSIRO report found that at Malabar, anywhere between zero and 79% of microplastics were removed from wastewater during the primary treatment process, while the Cronulla plant removed more than 98% of microplastics.

“The Cronulla WWTP was more effective at removing microplastics from wastewater than the Malabar WWTP,” the report said.

The analysis was based on samples CSIRO collected over a 24-hour period for 10 months at the Cronulla and Malabar plants.

Samples from Sydney waterways are tested for microplastics

Dr Scott Wilson, the research director at the Australian Microplastic Assessment Project, said it had been known “for a while” that wastewater treatment plants were the main source of microplastics pollution.

“The greater the treatment process the better it is at reducing microplastics that are coming through,” he said.

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“What is probably more amazing is the levels still coming out of a tertiary treated plant’s system [at Cronulla].”

Wilson said this should be remedied and Sydney Water should examine advanced tertiary treatment options.

“If you’re pumping billions of little particles into the environment, they’re bound to have effects over time, at least, if not straight away,” he said.

A Sydney Water spokesperson said the CSIRO study had concluded that the risk of contaminants from microplastics affecting marine organisms was “likely to be relatively low”.

“We have considered the findings of the report and are looking at potential treatment options, in consultation with our environmental and pricing regulators, to determine the best way forward,” they said.

Scientists take water samples from a Sydney waterway to test for microplastics. Photograph: Screenshot from EPA video

The water policy expert Prof Stuart Khan previously told the Guardian the “vast majority” of Sydney’s wastewater went into the ocean through the Malabar, Bondi and North Head plants.

Khan, who heads the school of engineering at the University of Sydney, said it was “not sustainable” to continue discharging “80% of the sewage produced by 5 million people into the ocean after only primary treatment”.

Workers in protective clothing clean up mysterious black balls on Coogee beach, Sydney
Sydney’s unusual sewerage system to blame for faecal and fat balls on beaches, experts claim
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Under its “long-term capital and operational plan”, Sydney Water intended to reduce its reliance on the coastal plants by processing more wastewater inland. New facilities would be built in Sydney stretching from Arncliffe to Quakers Hill.

An EPA spokesperson said microplastics were a “major threat” to the environment and it was analysing the results from its assessment of 120 waterways across NSW including Sydney Harbour and Parramatta River.

“This assessment, which was completed in mid-2024, will help us better understand what types of microplastics are out there and the scale and source of microplastics in our waterways,” they said. “A report on this work will be finalised by mid-2025.”

The spokesperson said previous work such as the CSIRO report had helped inform the bans on single-use plastic items such as plastic bags and straws introduced by the NSW government.

These bans had contributed to a 54% reduction in plastic litter in the environment since 2018, they said.

The CSIRO declined to comment.

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