In the 21st century, as the climate crisis accelerates desertification and threatens food security, it is unsustainable that much of the effluents from treatment plants continue to be discharged without being reused. In a world where water demand is projected to exceed availability by 40% by 2030, the reuse of every cubic meter becomes a strategic imperative. This project sits precisely at that breaking point: transforming an environmental liability into a regenerative solution for the agro-food sector. Located in the province of Alicante, Spain, within a region characterized by severe water stress and heavy dependence on intensive irrigation, the Effluent Reuse for Agro-Food Irrigation Project not only provides high-quality regenerated water, but also redefines the way agriculture can coexist with the planet’s limits.
The market situation is critical: the agricultural sector in southeastern Spain consumes more than 80% of the available water resources and faces growing restrictions on groundwater extraction and inter-basin transfers. Against this reality, the project’s strategic objective is twofold: on the one hand, to guarantee farmers a stable supply of water with traceable and validated quality; and on the other, to reduce pressure on overexploited aquifers and at-risk ecosystems. The rationale is clear: if no action is taken, agricultural competitiveness and regional food security will be seriously compromised. In this context, the actors involved, the wastewater treatment plant operator, the recipient agro-food company, the technology providers, and the external verification entity, form a collaborative ecosystem that ensures governance, traceability, and technical control under the VWBA 2.0 methodology, complying with the principles of additionality, intentionality, and traceability that guarantee the water benefit is real, measurable, and verifiable.
The main challenge is to reverse an agricultural model highly dependent on increasingly scarce and costly water sources. Currently, the treated effluents from the local WWTP are discharged into the environment without productive use, representing both a lost resource and an environmental risk. The technical opportunity is evident: through an advanced tertiary treatment system that integrates ultrafiltration membranes, UV disinfection, and real-time digital monitoring, the project transforms up to 1.2 million m³ of effluent annually into safe water for agro-food irrigation, equivalent to the annual consumption of more than 15,000 people.
The impact is immediate: reduced groundwater extraction, lower pressure on rivers and aquifers, and a reliable supply for high-value crops. In the short term, farmers benefit from lower water supply costs and greater resilience to droughts. In the medium term, the agro-food chain’s water footprint is reduced and competitive positioning in markets demanding sustainability certifications is improved. In the long term, the region strengthens its water and food security, generating a replicable model for other Mediterranean basins. This model is replicable because it combines proven technology, transparent governance, and both physical and digital traceability of the water benefit.
Strategic allies include the treatment plant operator, the irrigation community, agro-exporting companies, and the independent verification entity. Acting now is crucial: the window of opportunity opened by the transition towards a Water Positive economy not only ensures ESG compliance and competitive differentiation but also provides investing companies with a powerful narrative directly connected to the Sustainable Development Goals (SDG 6, 12, and 13) and the new European regulations on reclaimed water. This project makes agriculture a central part of the solution, demonstrating that every drop recovered is a step towards water security, climate resilience, and shared prosperity.
A tertiary treatment system with MBR technology (Membrane Bioreactor) has been installed, combining an aerobic biological process with a submerged membrane separation unit (ultrafiltration type) in a single compact module. The system is designed to operate continuously and automatically, with level, aeration, and transmembrane pressure controls, ensuring a purification capacity above 99% for critical parameters such as Biological Oxygen Demand (BOD), Total Suspended Solids (TSS), and fecal coliforms.
The treated water meets the quality standards required by ISO 16075 for the irrigation of food crops, as well as the requirements of Spanish legislation (Royal Decree 1620/2007) for agricultural uses. The treatment line also includes a UV disinfection chamber as an additional barrier against pathogens.
The regenerated water is stored in a closed food-grade polyethylene tank, equipped with level sensors, recirculation systems, and protection against recontamination. From there, it is distributed through a drip irrigation system to an agricultural plot dedicated to the production of vegetables and culinary herbs. This integration closes a local water cycle, reducing demand on external sources and preventing discharges into the environment.
Stage 1: Design and commissioning of the MBR system (months 1–2): Complete installation of the tertiary treatment system, including: (i) fine screening pre-treatment to remove coarse solids and fats; (ii) aerobic biological reactor with fine-bubble aeration diffusers; and (iii) submerged ultrafiltration (UF-MBR) membrane module in cross-flow configuration. The unit includes sensors for transmembrane pressure, dissolved oxygen, and temperature, allowing calibration of hydraulic retention times and optimization of aeration. Feed flow is measured using high-precision electromagnetic flowmeters, and operating conditions are controlled with a PLC and HMI interface.
Stage 2: Verification of treated water quality (month 3): Once the system stabilizes, monitoring of treated effluent quality begins. Representative samples of the reclaimed water are collected and analyzed in a certified laboratory for the following parameters: BOD5, COD, TSS, ammonium (NH₄⁺), nitrate (NO₃⁻), fecal coliforms, E. coli, pH, and electrical conductivity. Plant toxicity tests are also conducted. Results are compared with the limits established in RD 1620/2007 for irrigation of food crops and the thresholds of ISO 16075-2. Ion chromatography and spectrophotometry are used for nutrients, and plate culture techniques for bacteriology.
Stage 3: Implementation of the irrigation system and commissioning (month 4): Installation of the drip irrigation system, with automatic time controllers and FDR (Frequency Domain Reflectometry) soil moisture sensors. Treated water is pumped from the tank using a low-pressure dosing pump, with pressure control via manometers and regulating valves. The plantation, vegetables and aromatic herbs, is distributed in plots that allow sectorized irrigation management. Commissioning includes application uniformity tests, programming of irrigation cycles, and validation of agronomic conditions.
Stage 4: Continuous monitoring and operation (from month 5 onwards): An operational plan is established with weekly technical supervision and monthly auditing. Continuous monitoring of treated and reused volumes is carried out via inline flowmeters connected to a SCADA system. Effluent quality is verified through monthly analyses (BOD, coliforms, E. coli), and crop conditions are validated through phytosanitary inspections and soil salinity control. Quarterly satellite remote sensing with NDVI is performed to monitor vegetation vigor. The entire system is linked to a remote monitoring platform (IoT) to ensure traceability and rapid response to failures.
The project, developed by Restaurante Cachito in Elche (Alicante, Spain), consists of implementing an advanced wastewater treatment and reuse system to allocate 100% of treated effluent to irrigation of an associated agro-food plantation. The intervention addresses the need to reduce potable water withdrawals in a basin characterized by structural water stress and is based on principles of circular economy, water efficiency, environmental health, and sustainable food production.
The technical solution is based on installing an MBR system (Membrane Bioreactor) that combines an aerobic biological process with a submerged ultrafiltration membrane stage, achieving more than 99% removal of BOD, TSS, and pathogens. The system is designed for continuous flow, with an average capacity of 500–1,000 liters per day, and is equipped with transmembrane pressure sensors, dissolved oxygen control, and automatic aeration. The treated effluent undergoes final UV disinfection and is stored in a closed recirculating tank, from which it is pumped into the drip irrigation system.
The adjoining plantation, dedicated to producing vegetables and aromatic herbs for use in the restaurant’s kitchen, is irrigated through an automated system that integrates soil moisture sensors (FDR) and sectorized valves. The entire process is supervised through a remote monitoring platform (IoT), with continuous recording of volumes, water quality, system operating parameters, and full operational traceability.
The project aligns with VWBA 2.0 methodology, applying Appendix A-2 to estimate Volumetric Water Benefits through substitution of mains water previously used for irrigation. Simultaneously, it incorporates the WQBA approach, by improving wastewater quality and preventing its discharge into the environment. Additionality is guaranteed, as reuse would not have occurred without this investment; permanence is ensured, as the infrastructure is permanent; and traceability is maintained through sensors, digital records, and third-party validation.
From a basin perspective, the project operates within the Segura River Basin, one of the most water-stressed in Europe, where agricultural, urban, and tourism demand far exceed natural water availability, leading to aquifer overexploitation and saline intrusion. By reusing water on-site and closing the local water cycle, the project avoids pressure on external sources and eliminates discharges, contributing to water balance restoration and territorial resilience.
At the social level, the project promotes responsible production and consumption practices, generates ecosystem benefits, and reinforces the restaurant’s credibility as a sustainability leader. It also advances multiple Sustainable Development Goals (SDGs), including SDG 6 (Clean Water and Sanitation), SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), and SDG 17 (Partnerships for the Goals).
Overall, this is a replicable and high-demonstration-value initiative for the gastronomy and agro-food sector, positioning Restaurante Cachito as a reference point in the transition towards circular and climate-resilient food systems.
