Every day, billions of microplastic particles flow into Sydney’s ocean from the Malabar wastewater treatment plant. A CSIRO report has revealed that between 5.4 billion and 120 billion microplastics escape through the system daily, raising serious concerns about pollution and marine life.
Locals have long noticed unusual debris washing ashore, but few realised the scale of plastic contamination. Now, scientists have confirmed that Sydney’s outdated treatment plants are a major source of microplastics in the ocean.
Why Malabar Releases So Many Microplastics
Sydney’s coastal wastewater plants—Malabar, Bondi, and North Head—only provide primary treatment. This process removes large solids but allows tiny plastic particles to slip through. In contrast, the Cronulla plant uses tertiary treatment, which captures over 98% of microplastics before discharging water into the ocean.
The difference is striking:
-Malabar releases billions of microplastic particles daily.
-Cronulla, with its advanced treatment, discharges only 86 million to 350 million—a fraction of Malabar’s output.
Experts argue that upgrading treatment processes across all plants would significantly reduce pollution levels.
Microplastics Slip Through
Australian Microplastic Assessment Project research director Dr. Scott Wilson, warns that wastewater treatment plants are the main contributors to this pollution.
He emphasised that the level of filtration determines how much gets through. The more advanced the treatment, the fewer particles escape.
What alarms him most is that even Cronulla, which has the best filtration system, still allows microplastics to pass through. If the most effective plant can’t catch everything, the pollution from older, less advanced facilities must be far worse.
Wilson stresses the need for immediate action. He urges Sydney Water to upgrade filtration systems.
A Missed Opportunity to Fix the Problem
Sydney’s wastewater system is undergoing a $32 billion upgrade, but Malabar, Bondi, and North Head won’t receive major treatment upgrades. Instead, planners aim to reduce the amount of wastewater processed at these plants over the next 15 years.
Experts say this approach fails to address the root problem. Professor Stuart Khan, an environmental engineer, points out that 80% of Sydney’s sewage still gets dumped into the ocean after only basic treatment. He believes modern filtration systems should be installed at all major plants, not just a select few.
How Widespread Is the Issue?
Microplastic pollution isn’t just a problem for Sydney’s beaches. The NSW Environment Protection Authority (EPA) is investigating 120 waterways, including Sydney Harbour and the Parramatta River, to measure contamination levels.
Banning single-use plastics has helped reduce visible litter, but billions of microplastic particles continue to flow into the ocean daily through wastewater. The issue remains largely unseen, but its impact grows with each passing day.
What Needs to Happen Now?
The technology to filter out microplastics already exists. Tertiary treatment systems, like those used at Cronulla, could drastically cut pollution levels if applied to more plants.
Without urgent action, Sydney’s beaches and marine life will face increasing harm. Every day that passes without upgrades adds billions more plastic particles to our ocean—a problem too big to ignore.
Published 17-Feb-2025