In a global context where water scarcity and the depletion of natural resources threaten the resilience of coastal cities, the water reuse project at the Benidorm Wastewater Treatment Plant (EDAR) emerges as a bold, technical, and transformative response. Every year, Spain discharges more than 3,000 hm³ of treated wastewater into the sea without subsequent use, in a country where 74% of the territory already suffers from water stress. This reality is unsustainable. In the touristic epicenter of the Valencian Community, Benidorm faces the paradox of being a city with intense water demand, with summer peaks that triple its base population, while releasing thousands of cubic meters of regenerated water into the coastal environment that could be used for high-value non-potable purposes. This project breaks that paradigm.
Located at the Benidorm EDAR in Alicante, the project’s strategic objective is to transform an underutilized secondary effluent into a safe, traceable, and reusable resource for multiple urban and industrial uses, fully aligned with the principles of the circular economy and efficient water management. The system employs advanced tertiary treatment technologies, including microfiltration, ultraviolet disinfection, and real-time physicochemical parameter monitoring, to ensure that the regenerated water meets the highest quality standards. The strategic location of the project, in a city with high tourism seasonality, pressure on coastal aquifers, and growing demand for ecosystem services, makes it a flagship case.
Beyond operational efficiency, this project represents a structural transformation of the urban water model: it replaces freshwater abstraction with regeneration, reduces marine discharges, strengthens the municipality’s resilience to droughts, and generates net volumetric water benefits under VWBA 2.0 methodology, specifically with the “Volume Treated”. Digital traceability of regenerated flows and their final use ensures the intentionality of the benefit, while additionality is guaranteed by the absence of prior use of this resource.
The project is made possible by collaboration between the public operator of the Benidorm EDAR (EPSAR), the technology provider responsible for the tertiary system, and the water benefit structurer under the Water Positive framework. Its alignment with the SDGs, especially SDG 6 (Clean Water and Sanitation), SDG 11 (Sustainable Cities), and SDG 13 (Climate Action), not only allows for impact quantification but also enables strategic communication at institutional, community, and corporate levels. In essence, it transforms an environmental externality into a regenerative opportunity, where every recovered liter is a statement about the future.
The Benidorm EDAR reuse project stems from a concrete technical opportunity: harnessing the constant flow of treated effluent currently discharged into the receiving environment without generating value. In a city that can consume more than 50,000 m³ of water per day during summer and whose natural surroundings face growing pressure on coastal aquifers, implementing a robust tertiary system to produce high-quality reclaimed water represents a leap forward in water efficiency and climate resilience. The installed solution enables the transformation of more than 2.1 million m³ annually of secondary effluent into a resource suitable for irrigating green areas, street cleaning, industrial cooling, and potentially controlled aquifer recharge, depending on regulatory developments.
The technology employed, membrane filtration, ultraviolet disinfection, and continuous analytical control, guarantees superior water quality without chlorine use or toxic by-product generation. This model avoids emissions associated with the transport and production of potable water for non-potable uses, eliminates the need for nitrogen fertilizers in green areas due to residual nutrient content in the treated effluent, and reduces pressure on conventional sources, particularly coastal wells and reservoirs.
The impact is immediate: reduced freshwater abstractions, enhanced municipal water security, decreased discharges into the Mediterranean Sea, and improved water balance in a basin with medium-high stress. In the short term, the project helps secure summer supply without expanding infrastructure; in the medium term, it enables new uses with full digital traceability; and in the long term, it positions Benidorm as a national benchmark for sustainable urban reuse.
The model is scalable to other Mediterranean coastal municipalities facing similar challenges. Its technical, legal, and social replicability lies in the fact that it does not require structural regulatory changes, but rather strategic decisions and well-coordinated public-private partnerships. Water utilities, technology providers, municipalities, or companies with ESG objectives can lead such solutions, gaining visibility, early compliance with upcoming regulations, competitive differentiation, and access to Water Positive certifications or water benefit credits. Ultimately, those who lead reuse today will lead urban sustainability tomorrow.
The proposal is based on an integrated strategy of chemical, operational, and digital improvement, aimed at effectively resolving the main bottlenecks in the performance of UF and RO stages. This strategy includes:
This approach will allow for a net water recovery rate above 75%, with sustained improvements in permeate quality, fewer cleaning cycles, and a reduction in specific energy consumption per cubic meter treated.
Technologies or Actions Applied:
The system optimization is based on the incorporation of advanced chemical formulations specifically designed to prevent scaling and biofouling in UF and RO membranes. These products are formulated based on the ionic composition and physical-chemical characteristics of the treated water and are compatible with the membrane materials used in the plant. Dosing will be adjusted according to operational parameters and inlet water quality and managed via a fully automated system integrated into the facility’s SCADA, enabling continuous control and real-time adjustments.
Additionally, CIP protocols in both treatment stages will be reviewed and reformulated. Separate sequences of acid and alkaline cleaning will be established under optimal conditions of temperature, pH, and duration, adapted to the predominant type of fouling. Operational staff will be trained in the new protocols, and specific performance indicators will be implemented to validate cleaning effectiveness and extend equipment lifespan.
Monitoring Plan:
Technical-operational monitoring will include the installation and calibration of differential pressure sensors (ΔP), permeate flow meters, conductivity, and temperature sensors at critical system points. These instruments will allow real-time detection of deviations in hydraulic or water quality behavior that could signal a need for intervention. Specific membrane fouling tests, microbiological analyses to evaluate biological activity in the system, and systematic comparisons to the pre-intervention baseline will be conducted. Detailed records of chemical consumption and CIP frequency will be maintained to evaluate improvements in efficiency and sustainability.
Partnerships or Implementing Stakeholders:
Technical execution will be led by EPSAR, as the responsible operator of the WATER REUSE PLANT, in coordination with chemical solution providers experienced in tertiary treatment and membrane processes. Recipient municipalities of the reclaimed water—such as Benidorm, L’Alfàs del Pi, and La Nucía—will participate in performance validation and planning of final uses. These partnerships will ensure that the implemented improvements not only optimize internal plant operations but also deliver direct benefits to the regional distribution and reuse system.
The project involves a progressive, technically structured intervention divided into three main phases, conceived not only as an operational improvement but as a comprehensive urban sustainability strategy. The first phase includes an exhaustive operational diagnosis of the WATER REUSE PLANT, including the characterization of biofouling and scaling in UF and RO membranes, historical analysis of CIP operations, and hydraulic system performance. This stage will also include controlled pilot tests with different antiscalant and biodispersant formulations to select the most effective combination based on inlet water quality and specific system conditions.
The second phase focuses on the operational implementation of the optimized CIP protocols. These will include the application of specific chemical sequences with dynamic control of pH, temperature, contact times, and cleaning frequencies, all managed through the SCADA system. The chemical dosing system will also be modernized, automating critical process points and improving traceability and responsiveness to fouling events in real time. This phase is key to establishing an intelligent and adaptive operational dynamic that reduces operating costs and maintenance frequency.
Finally, the third phase will focus on technical validation and monitoring of real-world performance results. Key performance indicators (water recovery rate, permeate quality, specific energy consumption, CIP frequency, and membrane lifespan) will be compared to the previous baseline. A validated technical report will be produced, serving as a reference for scaling this methodology to other treatment plants within the EPSAR-managed system.
This project is part of Benidorm’s water strategy, a city recognized as a pioneer in integrating circular economy principles, water efficiency, and climate change adaptation into its urban model. By improving the performance of a key infrastructure in a water-stressed basin like Marina Baixa, it reinforces water security for the population, ensures continuous supply of reclaimed water for irrigation, and reduces pressure on natural resources. Moreover, this intervention constitutes a replicable model of technical and territorial sustainability in coastal tourist areas facing similar challenges.
