Microplastics are polymer particles less than 5 mm in size that have seeped into almost every corner of the planet, from wastewater and rivers to seas, soil, and ultimately the food chainAlthough they emerged due to their versatility and low cost, today they represent a major environmental and health challenge. The paradox is clear: they are omnipresent and persistent, but very difficult to intercept and measure..
This challenge also presents an opportunity. As research into its impacts and exposure pathways progresses, policies, decontamination technologies, and practices to curb its spread are being accelerated. The key lies in combining prevention, capture, degradation and, where possible, recovery.integrating solutions in wastewater treatment plants, industries, laundries and in the home itself.
What they are, where they come from, and why they are a cause for concern
By definition, microplastics include fibers, fragments, and spheres of millimeter size or smaller. They can be primary, produced already in minute dimensions for exfoliating cosmetics or technical cleaning products, or secondary, resulting from the fragmentation of products such as synthetic textiles, tires, paints, and packaging. Among the most critical sources are industrial pellets —also called nurdles—, 2 to 5 mm preforms included in the ISO 472:2013 standard and which represent a huge fraction of the plastic raw material.
Their global presence is enormous: recent estimates suggest tens of trillions of particles are floating in the oceans. Marine organisms mistake these pieces for food, suffering blockages, stress, and damage to filtering organs or gills. In humans, evidence on effects is still being built, but exposure is constant and particles are already being detected in food and water..
Measuring them is a headache. Techniques don't always distinguish plastics from other materials at submillimeter scales, and below 0,3 mm, and especially in the micron to nanometer range, there is no universal analytical consensus. This lack of standards makes it difficult to compare the performance of different technologies and to design demanding regulations..
Faced with this situation, international initiatives are emerging to stem the flow of plastics and microplastics into the sea. Institutional campaigns and United Nations resolutions are pushing to limit their presence, including the banning of microbeads in cosmetics in several countries. Prevention is crucial, but capture and degradation solutions are also needed at the points where they can best be treated..
Conventional treatments in wastewater treatment plants: limits, sludge and the water-soil dilemma
Wastewater treatment plants were designed to remove organic matter, nutrients like nitrogen and phosphorus, and solids, not to combat microplastics. Even so, their mechanical, biological and chemical lines They retain some of these particles by filtration or by their adhesion to flocs and precipitates. The problem is that the more they remove from the water, the more it ends up accumulating in the sludge..
Sludge can contain anywhere from tens to over 180 particles per gram on a dry basis, and is frequently applied to agricultural soils or landscaping projects for its fertilizing value. Studies estimate that the microplastic load in terrestrial environments can be 4 to 23 times greater than that found in oceans. This creates an uncomfortable dilemma: either you leave it in the water or you move it to the ground.
The effectiveness of conventional treatments against microplastics is variable and, in some cases, practically nil, according to reports. Furthermore, legislation is not always adequate: several European regulatory frameworks still lack an explicit limit for microplastics in treated wastewater. Without clear objectives, investments to improve their control tend to be delayed..
Some tertiary technologies stand out for their retention capacity. One example is membrane bioreactors, capable of filtering at the submicron scale. In advanced pilot projects, these plants have concentrated suspended solids up to 50 times for analysis, showing that most microplastics are diverted to sludge (around 80%), a residual fraction remains in the treated effluent (approximately 1–5%), and the rest is captured in other stages or incinerated. In certain analytical campaigns, particles as small as 50 μm were not even detected in the water treated by the membrane train..
The downside is cost: MBRs require more energy and maintenance than traditional sedimentation, which limits their adoption unless there are quality requirements, space constraints, or regulatory pressure. Even so, several local authorities are considering them as part of the solution to future limits on microplastics. If the regulations are introduced, MBRs could be a fast track to compliance..
Emerging technologies: magnetic capture, electrochemistry, and photocatalysis
Beyond conventional treatments, development is accelerating on three complementary fronts: physical separation processes, electrochemical platforms for coagulating or oxidizing polymers, and advanced oxidation processes by photocatalysis. The goal is to capture, degrade, or even valorize recovered plastic materials with energy efficiency and economic viability..
Magnetic capture and continuous solutions
One expanding line of research is selective agglomeration using magnetic materials. This approach involves dosing an inorganic absorber that adheres to plastic particles, forming aggregates. Thanks to the absorber's magnetic properties, the aggregate is separated using an external field, releasing the water flow. The great advantage is that the collector can be regenerated and reused, and the microplastics are recovered without damaging them..
There are solutions that operate continuously and combine detection, counting, and capture within the same process flow. In full-scale pilot projects, reductions of up to 76% in the initial concentration have been achieved in urban wastewater treatment plants capable of processing large volumes. The technique anticipates a chronic weakness of other options: preventing particles from ending up in the sludge..
In terms of efficiency and cost, these lines offer advantages over hydrocyclones—which require significant energy for centrifugal force—and membranes—which require frequent replacement. Furthermore, they can capture particles down to approximately one micron, outperforming solutions that are only effective at particles larger than 5 μm. The range of applications is broad: urban and industrial wastewater treatment plants, textiles, polymer manufacturers, food and beverages, laboratories and even household appliances.
Detection is also advancing with systems that quantify milligrams of microplastics per liter and are integrated into plants or industries to monitor and trigger corrective actions. In parallel, high-flow installations—on the order of one hundred thousand liters per hour—are being built to validate their scalability. Reusing the captured material even opens the door to design applications, such as panels or furniture made from recycled plastic..
Iron oxide nanoflowers: capture and destruction in two stages
In the field of materials science, iron oxide nanoflowers with large surface area and cooperative magnetic behavior have been developed. These nanostructures adhere to microplastics from sources such as cosmetics, magnetizing them in minutes and allowing for their removal with a magnet. Once separated from the water, a further step is taken: they are hydrolyzed and exposed to radicals generated by the nanoflowers themselves..
Radical generation occurs by locally heating the nanoparticles using alternating magnetic fields, without heating the water volume. The process operates at low temperatures and is energy-efficient compared to protocols that operate at around 90°C. The desired result is CO2 mineralization.2 and H.2Or, with reusable particles and scaled production to the gram level with costs cut in half.
These advances demonstrate that the magnetoseparation can be paired with clean degradation routesshortening times and allowing for attractive compact processes for industrialization.
Electrocoagulation: from loose polymer to filterable floc
Electrocoagulation uses consumable electrodes—for example, made of aluminum or iron—to release cations that neutralize and agglomerate particles. In municipal wastewater, aluminum electrodes have shown outstanding performance for microplastics, achieving between 90 and 100% under optimized conditions. The choice of electric field and energy management are key to balancing efficiency and costs.
The operating principle is simple: metal ions generate coagulants in situ, precipitates form with the plastic fraction, and the resulting solid is filtered or settled. The simplicity of the equipment, the limited consumption of external reagents, and the ease of integration as a post-treatment make electrocoagulation a strong candidate for polyurethane effluents. Their main challenge is managing the sludge generated, which must be treated responsibly..
Electrochemical oxidation: radicals that cut polymer chains
When the goal is to destroy the polymer, electrochemical oxidation takes center stage. Using advanced anodes, such as boron-doped diamond anodes, reactive oxygen species—hydroxyl radical, hydrogen peroxide and other oxidants—capable of breaking C–H and C–C bonds in plastics. With BDD, degradations of nearly 90% have been observed in hours, leading to CO2 as the main final product.
Operating parameters matter: applied current, electrolyte type and concentration, and reactor configuration. In the case of nanoplastics, sulfate radicals can outperform hydroxyl radicals, achieving conversions above 85% with BDD anodes. The major obstacle remains the need for high potentials and the appearance of side reactions that reduce faradaic efficiency.
Beyond disposal, there is the option of valorization. Under electrocatalytic conditions, the conversion of PET into terephthalic acid and hydrogen, two products of industrial interest, has been demonstrated. This approach integrates a circular economy, but requires fine process control to maximize selectivity and minimize parasitic reactions..
Photocatalysis and advanced oxidation processes
Another powerful family of processes are advanced oxidation processes based on semiconductors such as TiOâ‚‚2 or ZnO. Under adequate lighting, electron-hole pairs are generated; electrons in the conduction band reduce oxygen to superoxide radical, which in turn favors the formation of hydrogen peroxide and hydroxyl radical. These species successively attack the intermediates until CO2 mineralization occurs.2 and H.2O.
In real-world scenarios, combining separation and photocatalysis multiplies results. One approach successfully implemented in industrial laundries combines a temperature- and corrosion-resistant ceramic membrane—which retains microplastics and solids—with a photocatalytic reactor that removes any remaining particles, including nanoplastics and dissolved organic compounds such as pharmaceutical residues. Using low-energy LED lighting, 96% microplastic removal and over 98% solids removal have been achieved in laboratory tests and at scale in a hospital laundry..
The proposal fits perfectly into the circular economy: it allows water to be reused in new washing cycles, reduces irreversible scaling on membranes, decreases the frequency of chemical cleanings and cuts energy costs compared to operating filtration equipment alone. It is even estimated that treated water can be cheaper than fresh water, favoring zero net liquid discharge.
As a next step, work is underway on manufacture these membranes in 3D with geometries that optimize light capture for industrial use. Collaboration between universities and leading solar centers enhances the scalability and robustness of the system.
Measurement and verification: why TOC is the arbiter of mineralization
To confirm that a polymer has fully mineralized, it is not enough to see changes in infrared bands or detect fragments by chromatography. Total organic carbon is the metric that tells how much carbonaceous matter is actually left in the systemIf the TOC falls to expected levels, the oxidation process has ended and no significant organic residues remain.
Technology centers are already operating TOC equipment to validate its water decontamination capacity, including the degradation of microplastics. These tests are complemented by analytical techniques to identify intermediate components, but the final verdict is determined by the remaining carbon content. Without a rigorous measure of TOC, it is impossible to ensure that the process has gone beyond mere fragmentation..
Case studies, alliances, and industrial deployment
Public-private partnerships are accelerating the transition from laboratory to plant. In urban wastewater treatment plants, pilot projects using magnetic capture have demonstrated effectiveness and scalability, with agreements in place to operate in international markets such as Australia, Peru, and Colombia. In a reference WWTP, after characterizing the water and sludge lines, multiple polymers —PP, PE, PCL, PEA, acrylic, PTFE and PU— were identified in the form of pellets, fibers and fragments, with higher concentrations in the sludge line..
The results of the first pilot project showed a reduction of nearly three-quarters of the initial microplastic concentration, paving the way for its continuous implementation. This technology also boasts zero waste, as it allows for the recycling of the captured material. With pilot plants of 3.000 to 5.000 L/h and a high-flow facility under construction, the scale-up is underway.
Meanwhile, market reports categorize the technology families into three groups—physical, chemical, and biological. On the physical side, research is exploring adapting textile filters with stacked media (PCMs) to retain 3D particles, although their performance against nanoplastics remains to be demonstrated. Solutions from companies specializing in filtration for different industrial environments are also featured..
The report covers magnetic innovations with iron oxides —Fe2O3— capable of attracting and agglomerating microplastics for separation by magnets, with recent investment and plans for reuse of the magnetic particles. The challenge is to ensure its full recovery and assess its large-scale environmental impact..
Regulations and governance: the missing link
While science advances, public policy moves at different paces. Some countries have already banned microbeads in cosmetics, and international frameworks call for prioritizing policies against marine litter and microplastics. Even so, many European regions lack explicit limits on treated wastewater and have no control mechanisms fully integrated into their legislation. Without a standardized analytical framework and clear requirements, the comparison between technologies becomes biased and adoption slows down..
Looking ahead, frameworks are expected to emerge that mandate the monitoring and reduction of these particles in both wastewater treatment plants and water-intensive industries. This implies investing in systems that measure and act in real time, combining prevention—for example, by capturing fibers in domestic and industrial laundries—with robust removal technologies. The sooner the emissions tap is turned off, the easier it will be to prevent the problem from spreading to the soil via sludge..
Prevention, circularity and the real economy
Control costs less when generation is prevented. Reducing the use of single-use plastics, improving tire materials that release fewer particles, and developing capture devices in washing machines are high-impact strategies. In sectors such as textiles or food and beverages, integrating early detection and capture prevents microplastics from reaching sludge or products..
Valorization is another lever. Recovering microplastics without degrading them allows them to be transformed into boards or furniture, integrating them into value chains with a circular economy. If the goal is to eliminate them permanently, then TOC-verified mineralization is the objective. Both pathways, recycling or mineralizing, are compatible and are activated depending on the context and the polymer..
At this crossroads, the industry is already dealing with powerful figures: systems capable of treating from thousands to hundreds of thousands of liters per hour, with reductions of close to 80% in capture and more than 90% in degradation when using well-designed electrochemistry or photocatalysis. The optimal decision depends on water quality, polymer mix, solids loading, energy cost, and current or upcoming regulatory requirements..
As a backdrop, it's important not to lose sight of the scale of the problem. Vast quantities are reported to enter the water cycle daily, and the measurement itself remains a challenge between 0,3 mm and the submicron range. Without a unified metric, governance and investment prioritization risk falling short or targeting the wrong targets..
Everything points to a combined approach: strengthening tertiary treatment where it makes sense, deploying selective capture for problematic microplastics, pairing separation with destruction when necessary, and measuring with TOC to verify mineralization. Adding prevention measures in laundries and industrial processes will multiply the impact at the source..
Ultimately, the answer to microplastics is not a single miracle technology, but an ecosystem of solutions that is tailored to the type of water, the plastic fraction, and the objectives of each facility. With alliances between universities, technology centers, operators and manufacturers, the leap from pilot to standard is getting closer..
Looking at the body of evidence, a realistic path emerges: reinforced and well-audited conventional treatments, membranes and MBR where needed, magnetic capture as a low-cost operating lever, electrocoagulation for polishing currents with solids, and oxidation platforms —electrochemical or photocatalytic— for when destruction is appropriate. With reliable measurement and clear standards, the gap between the laboratory and the water leaving the plant can be closed quickly..