The Community of Madrid has launched a pioneering facility for the control and elimination of microplastics from wastewater , making it the first project of its kind in Spain at an operational wastewater treatment plant. The system is testing technologies already in use at other plants . It is currently operational at the Arroyo del Soto wastewater treatment plant (WWTP) in the municipality of Móstoles.
This new plant is the result of an agreement signed in July 2024 between Canal de Isabel II and the technology company Captoplastic , and it began operating in January. With its commissioning, the Madrid region is getting ahead of future European Union obligations regarding the control of emerging pollutants, especially microplastics present in the urban water cycle.
The initiative is part of the regional government's strategy to improve the quality of wastewater treatment and minimize the presence of plastic particles in effluent from treatment plants. Beyond its experimental nature, the goal is to test a scalable technology that can be progressively implemented in other facilities if the results prove successful.
According to the Community of Madrid, this project represents a significant step in protecting the region's water bodies by addressing a type of pollution that, due to its minute size, often goes undetected by conventional wastewater treatment systems, thus helping to prevent river contamination . In this way, the Madrid system aims to become a technical benchmark for other Spanish and European cities facing similar challenges.
The collaboration between the public operator Canal de Isabel II and the firm Captoplastic illustrates how cooperation between the public and private sectors can accelerate the implementation of technological solutions to complex environmental problems, in this case the filtering and removal of microplastics from urban wastewater.
How the installation works and what makes it different
The pilot plant incorporated into the Arroyo del Soto wastewater treatment plant uses an innovative system to capture microplastics . These particles , smaller than five millimeters, are particularly difficult to retain using traditional wastewater treatment processes based on microplastic removal technologies . They are highly resistant to degradation and can remain in aquatic environments for extended periods.
The heart of the system is a magnetic collector designed to adhere to the plastic fragments present in wastewater. After contact, the collector and microplastics together can be separated from the water flow and removed in a controlled manner, thus reducing the pollutant load that would otherwise reach rivers or other receiving waterways.
One of the key features of this development is its "zero waste" approach . The magnetic material used to bind the plastic particles is recovered after the process, allowing it to be reused in subsequent treatment cycles. This approach limits the generation of new waste associated with the purification process itself.
The installation has been designed to integrate seamlessly into the wastewater treatment plant's existing treatment chain without significantly disrupting normal operations, a key factor in assessing its potential future implementation at other plants within the network. The goal is for this type of system to be integrated into existing purification processes without requiring major structural modifications.
In this way, the Community of Madrid is not only testing a microplastic capture technology, but also its operational and economic viability in a real urban wastewater treatment environment, with variable flow rates and different characteristics of the wastewater that arrives at the plant.
Treatment capacity: up to 100.000 liters of water per hour
The pioneering facility in Móstoles has a treatment capacity of up to 100.000 liters of water per hour , a significant figure for a pilot project. This volume allows the technology to be tested under conditions similar to those of a typical operation.
The system is designed to operate continuously, treating the wastewater that passes through the Arroyo del Soto wastewater treatment plant and applying the magnetic capture process to the selected flow rate. This allows for the evaluation of how the technology responds to variations in the pollutant load or the daily flow rate arriving at the treatment plant.
The incorporation of this solution is not limited to a simple additional filter, but rather introduces a specific method for trapping very small plastic particles , which are precisely those that most easily escape conventional physical barriers. The installation's design aims to combine efficiency with operational stability.
This approach opens the door to the possibility, in the future, of expanding the treatment capacity or replicating the system in other wastewater treatment plants, adapting the size of the pilot installation to the needs and characteristics of each plant.
In parallel, the experience in Móstoles will allow the collection of information on energy consumption, maintenance needs and the behavior of the equipment over time, key aspects to determine if this technology is viable on a large scale in complex sanitation networks such as Madrid's.
Initial results: an effectiveness of over 80%
The trials carried out at the Arroyo del Soto wastewater treatment plant show, in this initial phase, an efficiency of over 80% in the removal of microplastics present in the wastewater treated by the system. These results are considered promising by those in charge of the project.
The tests focus on measuring both the plastic particle retention capacity and the quantification methods used to determine how many microplastics enter and exit the process. This analytical work is essential for obtaining comparable and reliable data.
In parallel, different operating conditions are being evaluated, such as variations in the treated flow rate or water composition, to verify whether the efficiency remains stable and to identify potential areas for improvement. The goal is to fine-tune the system before taking steps toward its expansion to other facilities.
The data collected will allow Canal de Isabel II and the Community of Madrid to assess the potential implementation of this technology in other wastewater treatment plants within the regional network . Based on the performance of the pilot plant, they will study whether it is advisable to adapt the design or size the system for different capacities.
In any case, the fact that, from the beginning, an effectiveness of over 80% has been recorded positions this technology as an alternative to consider in order to strengthen the fight against microplastics in the urban water cycle, an area where there is still room for technological improvement.
Microplastics: an emerging pollutant in the spotlight
Microplastics are tiny fragments of plastic less than five millimeters in size that do not dissolve in water and degrade very slowly in the environment. They come from a variety of sources, from cosmetics and synthetic textiles to the fragmentation of larger plastics.
The presence of these particles in rivers, lakes, seas, and, in general, throughout the water cycle, has become one of the most significant environmental challenges for the wastewater treatment sector . Their small size allows them to pass through conventional processes and accumulate in aquatic ecosystems.
For this reason, microplastics are considered an "emerging contaminant ." It is not a new problem, but it is a phenomenon about which there is growing scientific evidence and public concern. Their detection and quantification are complex, and their potential impact on the food chain and human health continues to be studied.
In this context, the development of specific technologies for its capture and elimination in wastewater treatment plants is becoming a priority for water cycle management companies, public administrations and research centers, both in Spain and throughout Europe.
The experience gained in facilities like the one in Móstoles can help define better practices and technical standards to address this type of pollution, combining engineering solutions with prevention policies at the source and changes in the production and consumption habits of plastics.
Anticipating European regulations and protecting ecosystems
The new European regulations on wastewater treatment already include the need to control and limit the concentration of microplastics and other emerging pollutants in wastewater discharges. This obliges Member States to adapt their treatment systems to meet increasingly stringent targets.
With the commissioning of this pioneering facility in Arroyo del Soto, Canal de Isabel II and the Community of Madrid are taking a step towards anticipating future regulatory requirements by testing advanced solutions before they become legally mandated. This proactive approach can facilitate a more gradual and less costly adaptation.
The project aligns with European policies for protecting aquatic ecosystems and improving water quality, reinforcing the role of wastewater treatment plants as a key barrier against pollutants entering the natural environment . Each improvement in the treatment process reduces the pressure on rivers and other receiving bodies of water.
Furthermore, the implementation of these types of technologies helps to strengthen the image of sanitation infrastructures as central elements of the ecological transition, not only responsible for purifying wastewater, but also for mitigating the presence of substances that until recently were hardly taken into account.
In the case of Madrid, the experience gained will allow the regional administration to assess which combination of measures is most appropriate to reconcile regulatory compliance, environmental protection and economic efficiency , with a view to future investments in the wastewater treatment network.
A potential model for other wastewater treatment plants in Spain and Europe
The commissioning of this pioneering facility in Móstoles places the Community of Madrid among the regions exploring advanced solutions to reduce microplastics in wastewater. Although it is a pilot project, its design aims to be replicable in other plants.
If the effectiveness and performance results are confirmed, the system developed by Canal de Isabel II and Captoplastic could serve as a model for other Spanish and European cities interested in strengthening their control of this type of pollution. The shared experience could accelerate the adoption of similar technologies outside of Madrid.
The project also illustrates the role of public water companies as agents of innovation, not just as managers of basic infrastructure. In this case, the combination of the public operator's technical knowledge and private technological expertise has made it possible to shape a concrete solution to a global problem.
In a context where a progressive tightening of environmental standards is expected, having real examples of technologies in operation can encourage other administrations to try similar proposals, adapted to their own realities and purification flows.
The Arroyo del Soto plant thus becomes a real-scale laboratory, where not only a new microplastic capture system is tested, but also a way of addressing water environmental challenges through a combination of innovation, regulation and responsible public management.
With this facility designed to control and eliminate microplastics from wastewater, the Community of Madrid incorporates into its purification network a tool that combines specific technology, public-private collaboration and anticipation of European standards, with initial results that exceed 80% effectiveness and that can set the course for other wastewater treatment plants in Spain and the rest of Europe.
