The Ebro River basin, one of the most vital and strategically significant water resources in the Iberian Peninsula, faces profound challenges related to structural water stress and the growing threat of diffuse microplastic pollution. During periods of extreme drought, river flows have recorded alarming decreases, with reductions of up to 40% at the river’s mouth (JRC, 2020). Adding to this visible crisis is the critical, yet invisible, issue of massive microplastic contamination, with over 2.2 billion microplastic particles annually discharged into the Mediterranean Sea (ICTA-UAB). This scenario urgently calls for bold, innovative, and fully traceable technological solutions capable not only of mitigating damage but radically redefining integrated water cycle management.
In response to this critical reality, the “Captoplastic Ebro” project emerges as a pioneering initiative that combines advanced technological innovation with the strategic principles of the Water Positive approach and the rigorous framework of Volumetric Water Benefit Accounting (VWBA 2.0). The project’s objective is clear: transform existing water-cycle infrastructures—including urban wastewater treatment plants (WWTP), industrial facilities, and regeneration stations—into systems capable of effectively detecting, quantifying, and removing over 80% of microplastics present in wastewater and sludge. Strategically located in Zaragoza, Spain, the project promotes collaborative efforts among public and private operators, technological experts like Captoplastic, external verification entities, and AquaPositive as the integrative coordinator of the model. Using a methodology ensuring the additionality, traceability, and intentionality required by VWBA 2.0, “Captoplastic Ebro” is not merely a technical solution but a paradigmatic transformation toward regenerative water management.
The project’s origin is rooted in the urgent need to address the exponential increase in microplastic pollution within the Ebro basin. Originating from industrial and urban activities, this invisible pollutant has become a latent threat to aquatic ecosystems, agricultural productivity, food security, and critically, public health. Conventional water-cycle infrastructures are not designed to effectively tackle this emerging threat, creating a concerning gap between daily operations and contemporary regulatory and social expectations.
The opportunity presented by “Captoplastic Ebro” lies in its dual approach: it not only captures and effectively eliminates microplastics but also transforms this pollution into a valuable asset, fostering a circular economy. The large-scale pilot plant, currently in an advanced installation phase with an operational capacity of 2,400 m³/day, will be fully operational by August 2025. This facility will conclusively demonstrate the viability, scalability, and effectiveness of this groundbreaking technology in complex urban environments.
The anticipated strategic and environmental benefits include immediate and substantial improvements in the quality of water returned to the natural environment, the generation of economic resources from previously disregarded waste, and a significant reduction in environmental and health risks. Collectively, these advantages represent a tangible revolution in sustainable and regenerative water resource management.
The proposed solution is structured around multiple action lines combining diagnostics, direct intervention, scalability, and integration into the water regeneration cycle. All measures are designed to measure and reduce microplastic load in the water environment and generate a quantifiable positive impact on water quality:
This intervention prevents these invisible pollutants from remaining in treatment processes, ensuring that water regeneration contributes to the Water Positive objective by returning higher quality water to the environment.
Phase 1 – Diagnosis and intervention design: baseline studies are carried out at urban and industrial WWTPs in the Ebro Basin. Using Captoplastic’s proprietary quantification technologies (based on magnetic capture, magnetic separation, and gravimetric quantification), microplastic concentrations are measured in effluents, sludge, and river receiving bodies, both upstream and downstream. This information enables the creation of a traceability map of the pollutant and the design of intervention strategies tailored to each facility, identifying priority sources and establishing reference parameters to evaluate additionality.
Phase 2 – Implementation of capture systems in urban and industrial WWTPs: modular continuous capture systems are installed between the pretreatment and primary treatment stages of selected plants. These systems are designed to retain plastic particles from 5 mm to 1 µm, with capture efficiencies exceeding 80%. Microplastic loads are measured before and after treatment to monitor capture efficiency. This phase allows for the generation of water quality benefits from the first year of operation, as well as the production of microplastic-free sludge that can be safely applied for agricultural purposes.
Phase 3 – Integration into emitting industries and regeneration lines: compact units up to 10,000 L/h are installed in industries such as industrial laundries, continuously measuring the treated volume and initial/final microplastic concentrations. Simultaneously, interventions are carried out on regenerated water lines to ensure that reused water is free of these pollutants, through monitoring and validation by composite sampling. This phase demonstrates the versatility and replicability of the technology in various operational settings.
Phase 4 – Territorial scaling, advanced monitoring, and Water Positive validation: the model is expanded to other WWTPs and industries in the basin, integrating a robust monitoring system based on key indicators: treated volume, percentage reduction of microplastics, final effluent quality, and traceability of captured waste. Monitoring is conducted through periodic sampling campaigns before and after treatment, using Captoplastic’s proprietary method based on magnetic collectors and gravimetric quantification, ensuring precision and auditability. Data is integrated into platforms like Aqua Positive to report water benefits under VWBA and WQBA, with technical support for external audits.
Project monitoring is structured through a combination of on-site technologies and laboratory validations. At each stage of the intervened water cycle (raw water inflow, effluent outflow, sludge generation, and regenerated water lines), manual sampling protocols and semi-automatic quantification are applied. Capture systems remove microplastics continuously, while manual sampling is periodically performed to obtain representative samples analyzed via Captoplastic’s quantification method, either in their laboratory or using semi-automatic in situ measurement equipment.
Microplastic concentrations (mg/L) are measured before and after technological intervention, both in water and sludge. Retention efficiency, treated flow rate, and unit operating conditions are also controlled. All data can be recorded on a digital platform with temporal and spatial traceability, enabling audit of results, visualization of historical series, and calculation of additionality and permanence metrics.
The Captoplastic Ebro project starts from a provocative yet necessary premise: water cannot be considered regenerated if it still contains microplastics. This assertion reveals a contradiction present in many current water infrastructures which, despite being labeled as regenerative, continue discharging invisible pollutants into the environment. In response, the project proposes a paradigm shift: moving from systems that merely “do no further harm” to truly regenerative infrastructures, capable of returning water of better quality than received.
This approach is framed within the Water Positive model and materializes through a validated technological solution that targets an emerging, invisible yet measurable contaminant with proven impacts on ecosystems, human health, and agriculture. The project’s differentiating value lies not only in its technical capacity but also in its full alignment with the principles of additionality, traceability, and permanence that govern the VWBA and WQBA frameworks. The intervention generates benefits that would not occur without its implementation: effective reduction of microplastics in wastewater, sludge, receiving water bodies, and agricultural soils.
Impact measurement enables quantification of microplastic concentration at different stages of the process, and through digital traceability on platforms like Aqua Positive, water compensation schemes and reporting under international frameworks such as SCS Global or CDP Water Disclosure are enabled.
The project also incorporates a circular economy dimension by valorizing captured microplastics, transforming them into new products such as plastic lumber. This zero-waste approach reinforces its contribution to the SDGs and positions it as a replicable reference. The solution is modular and scalable, applicable to both large urban WWTPs and smaller industrial facilities with a high contribution to microplastic pollution.
In summary, the Captoplastic Ebro project demonstrates that being Water Positive is not an aspirational discourse but a technical, measurable, and replicable reality. By acting on the invisible, it proposes a new regeneration metric based on restored quality and prevented environmental impact. Its implementation in the Ebro Basin can become a European model for transforming environmental liabilities into positive water benefits, aligned with science, the SDGs, and the new water quality regulatory framework.
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