Microplastic removal from water: conventional and advanced methods

Microplastic removal from water: conventional and advanced methods

Microplastics in water have become an important environmental challenge. These plastic particles, generally smaller than 5 mm, can enter rivers, lakes, seawater, and wastewater from several sources. These include synthetic textiles, tyre wear, packaging waste and personal care products.

Once released into the environment, microplastics are persistent, mobile and difficult to remove. Their size, shape, and chemical composition can also influence how they behave during water treatment.

Conventional water and wastewater treatment already includes several processes that can help reduce microplastic concentrations:

• Filtration: Water passes through a porous material that acts as a physical barrier. The particles retained depend on the filter material and pore size.
• Coagulation: Coagulants are added to destabilise small particles suspended in water. This encourages the particles to begin joining together.
• Flocculation: After coagulation, these small particles begin to bind and form larger clumps called flocs. These larger groups are easier to remove from the water.
• Sedimentation: When the flocs become sufficiently large and heavy, they settle at the bottom of the treatment tank and can be removed.

The performance of these methods depends on factors such as particle size, shape, density, polymer type, and treatment conditions. Very small microplastics can remain suspended in water and are therefore harder to remove completely.

For this reason, more advanced approaches are being studied:

• Membrane filtration: This method can retain a wider range of particle sizes. These systems can be very effective, although their performance can decrease over time because particles and organic matter build up on the membrane surface.
• Advanced oxidation and photocatalysis: These methods generate reactive species that can modify the polymer surface and promote microplastic degradation. However, complete degradation can be difficult, and partial treatment may produce smaller plastic fragments or intermediate compounds.
• Magnetic separation: Magnetic or magnetically modified materials can be used to capture microplastics. An external magnetic field is then applied to separate the resulting complexes from the water. This approach may help remove smaller particles that are difficult to capture using conventional methods.
• Electrochemical methods: Techniques such as electrocoagulation and electroflotation use an electric current to help destabilise, aggregate, and separate small particles from water.

Overall, no single method currently solves the problem on its own. Conventional treatment methods remain important, but smaller particles are still difficult to capture. Advanced systems can improve removal, but they often involve higher costs, energy consumption and operational complexity.

At CymitQuimica, laboratories studying microplastic removal from water can find filtration materials, metal oxides such as titanium dioxide, zinc oxide and iron oxides, adsorbents and analytical reagents to support their research.

For more information, contact our customer support team at support@cymitquimica.com.