Microplastics are everywhere. In the ocean, in freshwater, in soil, in the air, in food, in drinking water, in human blood. Particles smaller than 5mm, often much smaller - down to the nanometre scale - shed from synthetic textiles, tyre wear, packaging breakdown, and industrial processes.

The scale of microplastic contamination in marine environments is genuinely sobering. A 2023 study published in PLOS ONE estimated that there are approximately 170 trillion plastic particles floating in the world’s oceans, with concentrations increasing rapidly since 2005.

Cleaning up microplastics that are already in the ocean is, bluntly, not feasible at scale. The particles are too small, too dispersed, and too numerous for any current technology to address effectively in open water. The focus of most practical research is instead on stopping microplastics before they reach the ocean - filtering them from wastewater, stormwater, and industrial discharge.

Here’s where the research stands in 2026.

Wastewater Treatment

Municipal wastewater treatment plants are one of the primary pathways through which microplastics enter waterways. Every time you wash synthetic clothing, thousands of microfibers are released into the wastewater system. Conventional treatment processes capture some of these particles, but not all.

Studies have found that conventional wastewater treatment removes about 80-95% of microplastics, depending on the treatment process. That sounds good until you consider the volumes involved - a single treatment plant processing millions of litres per day can still release billions of microplastic particles into rivers and oceans even at 95% removal efficiency.

Membrane bioreactors (MBRs) are among the most effective existing technologies for microplastic removal. By filtering wastewater through fine membranes with pore sizes of 0.1-0.4 micrometres, MBRs can achieve removal rates above 99%. The limitation is cost - MBRs are significantly more expensive to build and operate than conventional treatment processes. Retrofitting existing plants is a major infrastructure investment.

Rapid sand filtration with coagulation (adding chemicals that cause particles to clump together) has shown removal rates of 97-99% in pilot studies. This approach is more economically viable for existing treatment plants than full MBR retrofits. Several Australian water utilities are investigating this approach.

Electrocoagulation is an emerging technique that uses electrical current to destabilise and aggregate microplastic particles, making them easier to filter out. Research from CSIRO has shown promising results in laboratory settings, with removal efficiencies above 98% for particles larger than 10 micrometres.

Washing Machine Filters

Since textile washing is a major source of microfiber pollution, filtering microplastics at the source - in the washing machine itself - is a practical intervention that’s gaining traction.

France became the first country to mandate microfiber filters on all new washing machines, with the requirement taking effect in 2025. Several other European countries are developing similar legislation.

External washing machine filters like the Filtrol and built-in lint filters designed for microfiber capture can reduce microfiber emissions by 80-90%. The technology is relatively simple - fine mesh screens that capture particles during the drain cycle - but adoption has been slow outside of regions with regulatory mandates.

Australia doesn’t currently mandate washing machine filters, but the Senate inquiry into microplastic pollution recommended exploring filter mandates as part of its 2024 report. Progress since that recommendation has been limited.

Stormwater Filtration

Stormwater is a significant but often overlooked pathway for microplastics. Rain washes microplastics from roads (tyre wear is a major source), urban surfaces, and construction sites into stormwater drains that typically discharge directly into waterways without treatment.

Bioretention systems (rain gardens) designed with specific filter media have shown microplastic removal rates of 70-90% in field trials. These systems use layers of sand, gravel, and engineered soil media to physically filter stormwater. The advantage is that they also remove other pollutants - heavy metals, nutrients, sediment - making them a multi-benefit investment.

Gross pollutant traps with fine mesh screens can capture larger microplastics (particles above 300 micrometres) from stormwater. These are relatively cheap to install and maintain, and they’re already used in many Australian municipalities for general litter capture.

Permeable pavements - surfaces that allow water to filter through rather than running off - have been shown to capture microplastics in the pavement structure. Research from RMIT University found that permeable concrete retained over 80% of microplastic particles in laboratory tests.

The Nanoplastic Challenge

Most current filtration research focuses on microplastics - particles between 1 micrometre and 5mm. But there’s growing concern about nanoplastics - particles smaller than 1 micrometre, down to the molecular scale.

Nanoplastics are harder to detect, harder to filter, and potentially more harmful biologically because they can cross cell membranes and enter the bloodstream. Conventional filtration methods that work well for larger microplastics are much less effective for nanoplastics.

Research into nanoplastic filtration is at an earlier stage. Approaches being explored include:

• Advanced membrane filtration with pore sizes below 0.1 micrometres (nanofiltration and reverse osmosis membranes)
• Magnetic nanoparticle capture - coating nanoplastics with magnetic particles and removing them with magnets
• Bio-based coagulants - using natural polymers derived from plants or microorganisms to aggregate nanoplastics for easier removal

These approaches work in laboratories but face significant scaling challenges. The energy costs of nanofiltration, the cost of magnetic nanoparticles, and the environmental implications of adding new materials to water systems all need resolution.

What Actually Matters

Filtration technology is important and the progress is real. But I want to be direct about something: filtering microplastics after they’ve been created is an end-of-pipe solution to a production problem.

The most effective way to reduce microplastic pollution is to reduce the production and use of materials that generate microplastics. Textile design that minimises fiber shedding. Tyre compounds that produce less wear particulate. Packaging redesign that eliminates unnecessary plastic. Extended producer responsibility schemes that make manufacturers accountable for the environmental fate of their products.

Filtration buys us time and reduces harm at the margin. It’s necessary and worth investing in. But it’s not sufficient on its own. The long-term solution requires upstream changes in how we produce and use plastic materials.

The ocean doesn’t care whether we filter 95% or 99% of microplastics from wastewater if we’re doubling plastic production every 20 years. The maths doesn’t work. Filtration needs to be paired with reduction, or we’re running on a treadmill.

The research is encouraging. The engineering challenges are being solved. But the policy and economic changes needed to actually turn the tide on microplastic pollution require broader commitment than the scientific community can deliver alone.