The project involves the implementation of a modular, scalable, and energy-efficient technological solution for the treatment and reuse of “mother liquor” generated during the fermentation and preservation of olives. The plant is located in a Mediterranean watershed under severe water stress, where increasing pressure on groundwater resources has created an urgent need for circular economy strategies.
The mother liquor, a highly concentrated saline solution containing organic acids, phenols, yeasts, and other recalcitrant organic compounds, has historically been considered a difficult-to-manage waste stream with a high environmental impact. Its prolonged storage or untreated discharge can have harmful effects on soils, groundwater, and receiving ecosystems.
The proposed intervention uses a synergistic combination of physical processes (multilayer filtration), advanced oxidation (e.g., acoustic cavitation or ozonation), and non-chlorine disinfection (such as UV radiation or cold plasma) to degrade organic matter, reduce salt loads, and ensure the safety of the treated water. This water is then reincorporated into the production process for reuse in stages such as washing and stabilization brines.
The system is designed for continuous operation, with minimal human intervention and no addition of chemical products, supported by a real-time automated control system. This enables the plant to close the water loop, completely eliminate discharges, and reduce net industrial potable water consumption by up to 90%.
The curing and preservation of olives generates a highly saline and pollutant liquid waste known as “mother liquor,” which results from the combined action of natural fermentation, brine addition, and contact with organic residues released during processing. This effluent is characterized by:
These factors make it difficult to treat using conventional biological methods. In many cases, the solution has been storage in evaporation ponds, which poses risks of aquifer infiltration and operational saturation. Some facilities opt to transport the waste to third parties for treatment, incurring high logistics costs and an associated carbon footprint.
Simultaneously, the olive washing process requires large volumes of freshwater (potable or well water), especially in pre-packaging stages, increasing pressure on local aquifers. In regions with limited water availability, this demand threatens both ecosystems and the operational continuity of agri-food industries.
The implemented technology allows for the comprehensive transformation of the saline effluent through a series of synergistic processes that effectively remove contaminants and recover water in optimal conditions for industrial reuse.
Initially, the mother liquor is captured directly from its points of generation in the plant and routed to a physical pretreatment stage, where suspended solids and coarse sediments are removed via screening and multilayer filtration.
Next, the stream undergoes an advanced oxidation process (AOP), which may combine technologies such as cavitation, ozonation, or activated peroxides to break down complex molecular structures and degrade persistent organic compounds. This treatment significantly reduces COD, polyphenols, and other recalcitrant elements. In parallel, efficient disinfection is carried out using non-chlorine methods (such as UV radiation or cold plasma), ensuring the elimination of microorganisms without generating harmful by-products.
The purified water is stored in an intermediate tank equipped with automated quality monitoring, and subsequently recirculated to the olive washing lines, preparation of new brines, or other auxiliary uses within the plant. This setup reduces freshwater intake by more than 80% and eliminates the need for external discharge, aligning with circular economy principles and environmental compliance.
SDG 6 – Clean Water and Sanitation: The project supports this goal by reducing freshwater withdrawal through a recirculation system and by properly treating a high-load effluent, preventing its discharge and improving water quality.
SDG 9 – Industry, Innovation and Infrastructure: It promotes the implementation of clean and innovative technologies that optimize industrial processes for water treatment and reuse.
SDG 12 – Responsible Consumption and Production: It fosters the transition toward circular models by converting mother liquor into a reusable water resource within the production process.
SDG 13 – Climate Action: It strengthens the climate resilience of the industry by reducing dependence on vulnerable water sources in a context of increasing water stress due to climate change.
SDG 17 – Partnerships for the Goals: It enables effective collaboration among different actors in the water ecosystem (plant operator, technology providers, authorities, and certifiers) to advance integrated sustainability solutions.
The treatment system comprises a sequence of interconnected modules designed for autonomous, continuous operation, ensuring both operational efficiency and process traceability.
Mother liquor is captured directly from the curing and preservation process through bypass pipelines equipped with automated valves and flow sensors. In the initial stage, the effluent passes through screening and multilayer physical filtration systems to retain suspended solids, organic particles, and olive residues.
Subsequently, the water is fed into an advanced oxidation reactor (AOP) where technologies such as in-line ozonation, acoustic cavitation, or hydroxyl radical treatment via cold plasma are applied. This stage breaks down recalcitrant organic compounds like polyphenols and significantly reduces COD.
The treated water then passes through a non-chlorinated disinfection unit using high-intensity ultraviolet radiation or electrochemical oxidation processes. This ensures pathogen removal without generating health-harming by-products or altering the physico-chemical quality of the water. Finally, the regenerated water is directed to an intermediate accumulation tank equipped with integrated quality sensors, from which it is recirculated to the washing lines, brine formulation, or equipment cleaning processes.
Monitoring Plan: Monitoring is conducted in real-time via an IoT sensor network measuring key parameters such as COD, electrical conductivity, turbidity, pH, and temperature. Data is transmitted to a digital platform that enables trend visualization, anomaly detection, and automated alert generation. A satellite remote sensing system is also integrated to assess correlations between water use, liquid waste generation, and seasonal variations in production. Result validation is complemented by monthly analyses conducted in an external ISO 17025-accredited laboratory.
Key Partnerships and Implementing Actors: he project involves several critical stakeholders. The company operating the plant is responsible for daily system management and operations. The technology provider supplies engineering, installation, and technical support for the modular system. The regional environmental authority oversees regulatory compliance, especially regarding discharges and water resource use.
This project aims to comprehensively transform water management at an olive processing plant in southern Spain by recovering and reusing the mother liquor produced during fermentation. It addresses two core challenges: pressure on the Guadalhorce River basin aquifers and the need to treat a highly saline, organic-loaded industrial effluent.
Mother liquor is a complex by-product with properties that hinder its treatment through traditional means: high salt concentration, recalcitrant organic compounds (phenols, proteins, polysaccharides), microbial presence, and low biodegradability. Its management has historically entailed high logistical, environmental, and regulatory costs. Simultaneously, the plant consumes significant volumes of potable or well water for washing and conditioning olives, in a region increasingly affected by water scarcity.
The proposed technological solution is a modular system combining physical pretreatment, advanced oxidation, and chemical-free disinfection, followed by automated recirculation. The design enables continuous operation, adaptation to fluctuating effluent loads, and achievement of water quality standards suitable for internal reuse. This setup reduces freshwater consumption by over 80%, eliminates discharges, and promotes a circular economy model replicable in other agro-industrial contexts.
The project stands as a scalable and replicable innovation for the agri-food sector in southern Europe, where water management is a strategic environmental and productivity factor. Its holistic approach not only ensures regulatory compliance but also anticipates emerging corporate water sustainability reporting frameworks.
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