Microplastic Removal Technologies: Strategies for Cleaner Water Systems

Microplastics—typically defined as plastic particles smaller than 5 mm—and nanoplastics, which measure below 1 µm, have emerged as pervasive environmental contaminants across aquatic ecosystems. These particles originate from the breakdown of larger plastic items or from primary sources such as synthetic fibers and industrial abrasives. Their persistence in water systems, coupled with their ability to adsorb toxic substances, has raised concerns about ecological and human health risks.

A critical question driving research and innovation is whether microplastics can be removed effectively from wastewater to prevent environmental exposure. While conventional wastewater treatment plants (WWTPs) can remove a substantial fraction—often between 88% and 94% depending on treatment stage—these systems are not optimized for complete elimination, particularly for smaller particles such as nanoplastics.

As a result, there is growing interest in advanced microplastic removal technologies that integrate filtration, adsorption, and novel materials science approaches. These technologies aim not only to improve removal efficiency but also to address sustainability through circular economy principles.

The challenge of microplastics in water systems

Microplastics enter wastewater systems through multiple pathways, including:

• Domestic washing (synthetic fibers)
• Industrial discharge
• Fragmentation of macroplastics
• Personal care products (microbeads)

WWTPs act as both mitigation points and emission sources, as they process large volumes of contaminated water yet still release significant quantities of microplastics into aquatic environments daily.

The challenge of removal intensifies with decreasing particle size. Nanoplastics are particularly concerning due to their ability to penetrate cellular membranes and evade conventional detection and filtration systems.

Established microplastic removal technologies

Primary and secondary treatment

Traditional WWTP processes (Figure 1) employ physical and biological methods, including:

• Sedimentation and flotation: Effective for larger particles (>27–149 µm)
• Biological treatment: Activated sludge systems can capture particles via bioflocculation

Removal efficiencies vary widely depending on plant configuration and particle size:

• Primary treatment: 16.5–98.4%
• Biological treatment: 78.1–99.9% using membrane bioreactors

Despite these high percentages, the sheer volume of wastewater processed means that millions of particles can still enter the environment daily.

Tertiary treatment

Advanced processes are typically required for improved removal:

• Sand filtration and coagulation
• Membrane filtration systems (microfiltration, ultrafiltration)

These technologies can increase removal to ~94%, but they often struggle with ultra-fine particles and operational challenges such as fouling.

Membrane-based microplastic removal technologies

Membrane processes use semi-permeable barriers to physically separate particles based on size. Key types include:

• Microfiltration
• Ultrafiltration
• Nanofiltration
• Reverse osmosis

These technologies are particularly effective for fine particle removal and are increasingly considered among the most promising approaches.

A study published in the journal Membranes showed that:

• Microfiltration membranes can achieve >99% removal of microplastics under optimal, controlled conditions
• Near-complete rejection has been reported for larger fragments
• Fiber removal efficiencies may reach ~98%

Despite high performance, membrane systems face challenges:

• Membrane fouling by particulates and biofilms
• High energy and operational costs
• Potential release of polymer fragments from membranes themselves

Adsorption-based approaches: Activated carbon and beyond

Adsorption technologies rely on interactions between microplastics and the surface of adsorbents, including:

• Hydrophobic interactions
• van der Waals forces
• Electrostatic attraction
• π–π interactions

Carbon-based adsorbents—including activated carbon, biochar, graphene, and carbon nanotubes—are widely studied due to their high surface area and tunable properties.

Activated carbon in microplastic removal

Activated carbon can be integrated into existing treatment systems with minimal modification. It operates via:

• Physical trapping in porous structures
• Surface adhesion interactions

Granular activated carbon has demonstrated removal efficiencies exceeding 95% under optimized conditions.

Figure 1: A diagram of microplastic removal technologies often used in wastewater treatment plants. Credit: AI-generated image created using Google Gemini (2026).

Case study: Circular activated carbon from epoxy waste

A notable innovation in microplastic removal technologies involves converting waste polymers into functional adsorbents.

Researchers from the University of Waterloo developed a method to transform epoxy waste—a non-recyclable thermoset polymer—into activated carbon using thermal decomposition. The resulting material was then used to treat nanoplastic-contaminated water.

Key stages include:

1. Thermal decomposition: Epoxy waste is pyrolyzed to produce carbon-rich material
2. Activation: Development of a porous structure with high surface area
3. Application: Adsorption and physical trapping of nanoplastics

The system achieved:

• 94% removal efficiency for nanoplastics
• Effective capture through physical entrapment within the carbon matrix

The underlying mechanism is primarily physical filtration rather than chemical adsorption, with nanoplastics immobilized within the porous structure.

The model nanoplastics were derived from polyethylene terephthalate, a polymer widely used in water bottles and textiles. These particles represent a significant environmental concern due to their bioavailability and toxicity.

Lead researcher Prof. Tizazu Mekonnen emphasized the broader sustainability implications of this technology: “Rationally designed plastics not only can be part of the solution to reduce climate change but can have a positive impact in economic development and create jobs.”

“This technology has the potential to significantly reduce the carbon footprint of the plastics industry.” — Prof. Tizazu Mekonnen, associate professor at the University of Waterloo.

“To end the plastic waste crisis and reduce the environmental impact of plastics production, we need to implement a circular economy approach that considers every stage of the plastic journey,” Mekonnen added.

Emerging and hybrid microplastic removal technologies

Biological and bio-inspired systems

Innovative approaches include:

• Engineered algae systems for microplastic capture
• Biofilm-based trapping mechanisms

These methods aim to combine removal efficiency with low energy consumption and sustainability.

Advanced oxidation and coagulation

Chemical processes can aid in removal by:

• Altering particle surface properties
• Promoting aggregation into larger, more easily removable clusters

Hybrid systems

Combining multiple treatment modes is increasingly common. Hybrid systems often deliver superior performance compared to standalone technologies.

Analytical techniques for microplastic detection

Reliable detection and characterization are essential for evaluating removal performance. Common laboratory techniques include:

• Fourier transform infrared spectroscopy: Identifies polymer composition
• Raman spectroscopy: Enables high-resolution analysis of small particles
• Scanning electron microscopy: Visualizes morphology and surface interactions

These tools help quantify removal efficiency and understand interaction mechanisms within treatment systems.

Future directions in microplastic removal

Key challenges for deploying microplastic removal technologies include:

• Scaling laboratory systems to municipal WWTPs
• Managing mixed contaminant streams
• Ensuring economic viability

As detection capabilities improve, research is increasingly focused on:

• Removal of particles <100 nm
• Minimizing health risks associated with cellular penetration

Technologies such as epoxy-derived activated carbon illustrate a shift towards:

• Waste-to-resource approaches
• Reduced reliance on virgin materials
• Lower lifecycle emissions

The question of how to remove microplastics from water remains complex, requiring a combination of engineering, materials science, and environmental chemistry. While conventional wastewater treatment systems achieve relatively high removal rates, they fall short in addressing smaller particles and preventing environmental release.

Emerging microplastic removal technologies, particularly those based on membrane filtration and advanced adsorption materials, are pushing the boundaries of efficiency. Innovations such as activated carbon derived from waste polymers highlight the potential for circular solutions that simultaneously address plastic pollution and resource recovery.

This article is a rework of a press release issued by the University of Waterloo. Material has been edited for length and the content has been updated to provide additional context and details of related developments since the original press release was published on our website. This content includes text that has been created with the assistance of generative AI and has undergone editorial review before publishing. Technology Networks' AI policy can be found here.