In a world where the climate crisis is redefining the resource economy, water has become the cornerstone of global stability and the driving force behind new sustainable economies. More than 3 billion people live under water stress, and projections indicate that by 2050, water demand will exceed available supply by 56%. In this context, cities in southern Europe face a double pressure: maintaining their economic development while ensuring their resilience to climate change. Córdoba, located in the Guadalquivir basin, one of the most strained and vulnerable in the country, takes on this challenge with a strategic and transformative vision. The La Golondrina Wastewater Treatment Plant becomes the heart of a new water economy, where traditional infrastructure evolves into a regenerative system capable of generating water, energy, and environmental value.
Inaugurated in 1991 and managed by EMACSA, the plant was a pioneer in advanced treatment in Andalusia. Today, its modernization drives a technical and conceptual revolution: moving from purification to regeneration. Producing 3 hm³ annually of usable water, enough to supply more than 40,000 people or maintain 450 hectares of agricultural and urban green areas, contributing directly to regional water security. Its model integrates technological innovation, advanced filtration, UV disinfection, and membrane technologies according to the required water quality, participatory governance, and impact measurement under the Volumetric Water Benefit Accounting (VWBA 2.0) framework, ensuring additionality, traceability, and intentionality in every regenerated liter.
The project’s potential transcends the city’s limits: it demonstrates how urban infrastructure can become a driver of territorial sustainability, reducing dependence on natural sources, improving water quality, and strengthening the climate resilience of the entire basin. Its impact is measurable, replicable, and aligned with European goals for reuse and climate neutrality.
La Golondrina symbolizes a paradigm shift: every regenerated liter not only returns water to the system but also generates resilience, employment, and hope in a Water Positive future for Andalusia and the Mediterranean.
Located in the Guadalquivir basin, a region marked by water stress and climate variability, the La Golondrina WWTP represents a technical and strategic response to one of Andalusia’s greatest environmental challenges. The plant, located in Córdoba and managed by EMACSA, leverages its advanced biological treatment infrastructure to take a leap toward water regeneration through the incorporation of a tertiary line with filtration, ultraviolet disinfection, and membrane technologies according to the required water quality.
This system allows the transformation of more than 3 hm³ of treated effluent per year into high-quality regenerated water, equivalent to the annual consumption of 40,000 households or the sustainable irrigation of 450 agricultural and urban hectares. The project offers direct and immediate benefits: reduction of potable water consumption, 42% reduction in CO₂ emissions, energy recovery through biogas, and decreased discharges into the Guadalquivir River. This intervention replaces polluting inputs with circular solutions, providing long-term water security and operational stability.
La Golondrina is made possible thanks to a public–private partnership between EMACSA as operator, the Guadalquivir River Basin Authority as the basin authority, the Andalusian Government as regulatory framework, and technological partners specialized in reuse and digital control. This model not only demonstrates technical efficiency but also scalability: it can be replicated in other Andalusian and European WWTPs with similar conditions, integrating into the Water Positive framework.
Acting now is key, as new European Union regulations, such as Regulation 2020/741, require increased water reuse and reduced urban water cycle emissions before 2030. Companies leading or partnering in such projects gain tangible advantages: ESG compliance, competitive differentiation, access to green markets, and reputational positioning as climate action leaders.
La Golondrina does not just treat water, it redefines urban infrastructure as a driver of regeneration, innovation, and shared value.
The project implementation is structured in progressive technical phases integrating engineering, risk management, and continuous monitoring. In the first stage, the design and sizing of the advanced tertiary system are developed, consisting of high-capacity filtration, ultraviolet disinfection, and membrane technology modules according to the required water quality, selected after evaluating alternatives such as constructed wetlands or MBR systems. The choice responds to criteria of efficiency, economic feasibility, climate adaptability, and regulatory compliance under RD 1620/2007 and Regulation (EU) 2020/741.
This grey infrastructure, complemented by SCADA digital control tools, has a treatment capacity exceeding 8,200 m³ per day, directly benefiting more than 150,000 inhabitants. The system is completed with 2,000 m³ storage tanks equipped with multiparameter sensors that record pH, turbidity, residual chlorine, and flow in real time, ensuring full traceability under the VWBA 2.0 framework.
The technical and strategic justification is based on reversing a structural problem of water losses, high demand, and environmental pressure on the Guadalquivir. The selected solution enables recovery of 3 hm³ of water per year, reduces the pollutant load of the effluent, and strengthens the city’s water security.
Its suitability lies in its ability to adapt to hydrological variability and guarantee efficiency and replicability in urban and agricultural contexts in southern Europe. Quantifiable benefits include regeneration of water equivalent to the consumption of 40,000 households, a 42% reduction in energy consumption, and 1,200 tons of CO₂ avoided annually, in addition to improved aquatic biodiversity and creation of specialized green jobs. Socially, it contributes to resilience, public health, and environmental awareness; economically, it reduces operational costs, increases self-sufficiency, and consolidates Córdoba as an ESG benchmark.
Project implementation is organized under a phased and adaptive framework, with clearly defined technical stages ensuring control, traceability, and continuous improvement.
Phase 1 – Diagnosis and Design: Hydrological, chemical, and operational characterization of the effluent is conducted, establishing the baseline reference for flow, quality, and emissions. This stage includes flow studies, water balance, and laboratory analyses, defining performance indicators (BOD, TSS, total N, total P, energy consumption, m³ treated) used to measure “with project” vs. “without project” conditions.
Phase 2 – Engineering and Construction: The tertiary treatment line is implemented, integrating advanced filtration, ultraviolet disinfection, and membrane technologies according to required water quality. This technology was selected for its high performance, low energy consumption, and compliance with RD 1620/2007 and Regulation (EU) 2020/741. Installation includes electromagnetic flow meters, multiparameter probes for pH, turbidity, residual chlorine, and IoT sensors connected to a SCADA system to ensure real-time monitoring and digital traceability. Nominal capacity exceeds 8,200 m³/day with operational efficiency above 90%.
Phase 3 – Commissioning and Continuous Operation: This phase includes system validation, continuous performance monitoring, and verification of water benefits under VWBA principles (additionality, traceability, and intentionality). Data are collected continuously via sensors and accredited laboratory controls, with quarterly reports to adjust operational parameters. Control mechanisms include automatic alarms for deviations, redundancy of critical equipment, and predictive maintenance to ensure service continuity.
Phase 4 – Validation, Verification, and Communication: External audits and independent verifications confirm the magnitude of volumetric and qualitative benefits generated. Certified performance and sustainability reports are issued based on audited data, ensuring transparency before CHG, EMACSA, and international verification bodies. Results are integrated into the digital platform Water Positive Córdoba, communicating environmental and social achievements.
The project incorporates a shared governance plan among EMACSA, CHG, the Andalusian Government, and verification entities, with defined roles for operation, maintenance, monitoring, and reporting. Agreements establish rights and uses for regenerated water as well as maintenance and validation responsibilities. A preventive and corrective maintenance program ensures system efficiency and durability.
Finally, the monitoring and continuous improvement framework applies VWBA/WQBA methodology to record regenerated m³, improved quality, and removed contaminants. Comparison between “with” and “without” project scenarios is performed through water balances and annual performance analyses. Results are communicated in progress reports and external audits, ensuring benefit permanence and technological updating over time.
The La Golondrina WWTP – Reuse and Circular Energy Córdoba Project constitutes a comprehensive technical intervention aimed at regenerating urban water resources and optimizing the water cycle from a circular perspective. The main intervention is the reuse of treated effluent through an advanced tertiary system combining filtration, ultraviolet disinfection, and membrane technologies, adapted according to the water quality required for each use. This process is complemented by a cogeneration plant that utilizes biogas produced in the sludge line to generate clean energy, and by a distribution network supplying agricultural, urban, industrial, and environmental sectors. Technically, the facility treats 8,200 m³ per day and produces up to 3 hm³ per year of regenerated water, complying with WHO standards, ISO 14046, Royal Decree 1620/2007, and Regulation (EU) 2020/741. Its design incorporates advanced digital instrumentation, IoT sensors, SCADA systems, and multiparameter monitoring, ensuring operational control and full traceability from collection to final use point.
This solution is key to addressing the structural water deficit of the Guadalquivir basin, characterized by aquifer overexploitation, reduced ecological flows, and dependence on surface resources. Before the project, treated water was discharged directly into the river without utilization; with its implementation, it becomes a strategic and safe resource. Its adoption reduces pressure on ecosystems, optimizes urban water management, and strengthens community water security. In this hydrological and social context, it represents the most suitable alternative due to its climate adaptability, energy efficiency, and regulatory compliance, providing measurable and sustainable solutions to climate change.
Expected results include recovery of 3 hm³ of water per year, reduction of 1,200 tons of CO₂ through biogas use, and improved effluent quality, over 95% BOD removal, 90% TSS, and 70% nitrates. Additional benefits include enhanced biodiversity, reduced health risks, and guaranteed water supply during drought conditions.
From a strategic and commercial standpoint, the project reinforces the Water Positive roadmap of EMACSA and Córdoba, delivering tangible ESG benefits: regulatory compliance, competitive differentiation, international reputation, and consolidation of a social license to operate. It aligns with Science Based Targets for Water (SBTi4Water), Net Positive Water Impact (NPWI), and ESRS E3 standards, actively contributing to SDGs 6, 7, 9, 11, 12, 13, and 17.
Its model is replicable in other Mediterranean basins, semi-arid areas, or industrial hubs facing water stress. Technological modularity, institutional backing, and public–private partnerships enable scaling to different geographic contexts. The success of La Golondrina depends on cooperative governance among EMACSA, CHG, the Andalusian Government, universities, and local communities, facilitating expansion and international validation.
The expected final impact is a substantial improvement in the Guadalquivir basin’s water balance, reducing extractions and strengthening resilience against extreme climatic events. Socially, it generates green jobs, improves public health, and ensures equitable access to safe water. For investors, companies, and citizens, La Golondrina represents an exemplary case of how water innovation drives a regenerative economy, where each liter returned to the system symbolizes a tangible commitment to the planet’s future.
The relevance of this solution lies in addressing the structural challenge of the Guadalquivir basin: water deficit, aquifer overexploitation, and dependence on surface resources. Compared to the baseline situation, where treated water was discharged unused into the river, the project creates an additional, safe, and traceable source of up to 3 hm³/year of regenerated water for agricultural, urban, industrial, and environmental uses; it decreases natural source extractions, reduces discharges, and improves ecological flows. In accordance with WHO standards, RD 1620/2007, and Regulation (EU) 2020/741, and under VWBA 2.0 verification, each generated cubic meter is recorded and attributed without double counting, consolidating water resilience, operational efficiency, and measurable benefits for both the basin and the community.
