Textile dyeing in the Mediterranean region consumes enormous volumes of freshwater and generates highly polluting wastewater, creating pressure on already scarce water resources and surrounding ecosystems. Our demonstrator introduces a supercritical CO₂, water-free dyeing process that removes the need for water, dyes, salts, and chemical effluent. The project aims to validate this technology at pilot scale by working with local dyehouses to replace multi-stage aqueous dyeing with a single, closed-loop CO₂ process. Initial results show 100% water savings, zero wastewater discharge, and 30–40% lower energy use. This demonstrates a practical WEFE-aligned solution that can ease regional water stress while enabling cleaner and more efficient textile production.
The Mediterranean region faces accelerating pressure on its water, energy, and ecological systems, driven by climate change, population growth, and resource-intensive industries. In Tunisia and neighboring Southern Mediterranean countries, water scarcity has intensified over the past decade as droughts become more frequent and aquifers decline. Industrial activities—particularly textile dyeing—exacerbate this stress. Traditional dyeing of cotton requires massive volumes of freshwater and generates highly polluted wastewater containing dyes, salts, alkali, and toxic auxiliaries. Treating this wastewater is energy-intensive and costly, and in many areas, treatment plants cannot fully remove contaminants before they reach natural ecosystems.
Textile production clusters concentrated in coastal and semi-arid areas face combined hydrological and ecological challenges: over-extraction of freshwater, degradation of water bodies, rising salinity, and contamination affecting agriculture and local biodiversity. This creates socio-economic vulnerability for communities dependent on both textile manufacturing and agricultural livelihoods. As water becomes scarcer, competing demands between industry, households, and food production intensify.
At the same time, the textile sector remains a major employer in Tunisia and across the Mediterranean, but it operates with outdated, water-dependent dyeing processes that are no longer compatible with tightening environmental regulations (EU wastewater directives, ZDHC standards, and brand-level sustainability requirements). Many dyehouses risk losing competitiveness or shutting down if they cannot reduce their water use and environmental footprint.
These intersecting water, energy, and ecosystem pressures create an urgent need for practical, scalable WEFE-aligned innovations that reduce industrial water consumption, lower energy demand, eliminate toxic effluent, and enable cleaner production systems. The demonstrator presented here responds directly to this challenge by targeting one of the region’s most water-intensive industrial processes.
The aim of this demonstrator is to introduce a practical, scalable, and WEFE-aligned alternative to traditional cotton dyeing, one of the most water-intensive and environmentally damaging industrial processes in the Mediterranean. The project focuses primarily on the Water–Energy–Ecosystems dimensions of the nexus, while indirectly supporting the Food dimension by reducing industrial pressure on shared freshwater resources needed for agriculture.
The main goal is to demonstrate that a supercritical CO₂, water-free dyeing process can replace multi-stage aqueous dyeing, eliminating the need for freshwater, reducing energy consumption, and preventing chemical effluent from entering natural ecosystems. By doing so, the project aims to contribute to regional water security, lower industrial energy demand, and protect aquatic and coastal ecosystems from persistent chemical pollution.
To ensure relevance and feasibility, preliminary stakeholder consultations were conducted with textile dyehouses, research partners, and regional industry experts. These discussions helped refine the technical objectives, identify operational constraints, and ensure that the demonstrator addresses real industry needs, especially the urgent challenge of operating under worsening water scarcity and tightening EU-aligned environmental regulations.
The envisioned timeline includes a first phase of technology validation at pilot scale (TRL6) followed by incremental optimization and industrial testing within dyehouses in Tunisia.
Short-term goals (2025–2026):
- Validate the one-step CO₂ dyeing process for cotton
- Quantify water, energy, and pollution reductions
- Build the operational dataset needed for certification
Long-term goals (2026–2030):
- Deploy water-free dyeing units in regional dyehouses
- Reduce industrial freshwater demand at scale
- Improve ecosystem protection by eliminating wastewater discharge
- Provide a replicable WEFE-aligned model for Mediterranean textile clusters
This intervention ultimately aims to demonstrate a sustainable pathway for reconciling industrial productivity with water and ecosystem preservation.
The demonstrator began by addressing the most critical challenge in Mediterranean textile regions: the heavy dependence of cotton dyeing on freshwater and energy-intensive wastewater treatment. The project first focused on establishing the technical basis for a supercritical CO₂, water-free dyeing process, starting with laboratory validation in collaboration with the Chemistry & Process Engineering Laboratory at the Faculty of Sciences of Monastir.
The initial actions included high-pressure experimentation, dye–CO₂ solubility studies, cellulose surface reactivity assessments, and controlled dye fixation trials. These technical steps confirmed the viability of a one-step, closed-loop CO₂ dyeing process capable of eliminating water use and significantly reducing energy demand. This phase involved a core scientific team of 4–6 researchers and engineers working across chemistry, applied physics, and process engineering.
Parallel “soft” interventions took place during this stage: stakeholder consultations with local dyehouses, discussions with sustainability managers from textile groups, and technical interviews with operators to understand daily constraints, equipment limitations, and regulatory pressures. These engagements ensured that the demonstrator responds to actual industrial needs and ecosystem challenges, rather than remaining a purely academic development.
The succession of actions followed a WEFE-aligned progression:
- Water dimension: Validate the complete removal of water and effluent from the dyeing process.
- Energy dimension: Measure reductions in thermal load, cycle time, and overall energy consumption.
- Ecosystem dimension: Evaluate the elimination of chemical discharge and its potential benefits for surrounding water bodies.
The project is now in the implementation phase of constructing a pilot-scale TRL6 CO₂ dyeing unit, planned for deployment in Tunisia. This unit will enable real-world testing with regional dyehouses, allowing broader participation from industry operators, local technicians, and environmental stakeholders.
The main achievement of the demonstrator to date is the successful validation of a one-step, water-free dyeing process for cotton using supercritical CO₂ something previously considered technically unfeasible. This breakthrough directly addresses the core WEFE challenges in Mediterranean textile regions by removing the need for freshwater, lowering energy use, and eliminating chemical effluent.
Across the Water dimension, the project demonstrated a 100% reduction in water consumption for the dyeing stage and complete avoidance of wastewater generation. This significantly reduces pressure on aquifers already stressed by droughts and agricultural demands.
Across the Energy dimension, experimental results showed 30–40% lower thermal energy requirements compared to traditional dyeing, due to shorter process cycles and the absence of water heating, rinsing, and drying. These savings are particularly relevant for regions facing rising energy costs and grid instability.
Across the Ecosystems dimension, the elimination of dyes, salts, alkali, and chemical discharge represents a major improvement over conventional dyeing, which often contributes to the deterioration of rivers, coastal zones, and groundwater quality. By preventing chemical effluent at the source, the technology offers a direct protective effect for local ecosystems.
While the project is still progressing toward TRL6, its objectives have been partially achieved: the scientific validation is complete, the process parameters have been optimized at lab scale, and a pilot machine is now under development. The strongest successes were in water elimination and pollutant prevention; the least advanced area is industrial-scale deployment, which is planned for the next phase.
Beyond technical outcomes, the project has generated greater strategic impact: it has attracted interest from dyehouses, policy actors, and innovation programs focused on water conservation in North Africa. It is contributing to regional capacity-building by introducing a replicable model for sustainable textile processing that aligns with future Mediterranean water and environmental policies.
A key lesson from this demonstrator is that meaningful sustainability gains in the Mediterranean can be achieved by targeting resource-intensive industrial processes rather than only end-of-pipe solutions. By eliminating water use and chemical effluent at the source, the project showed that WEFE benefits can be delivered more effectively and at lower long-term cost compared to traditional wastewater treatment and mitigation strategies.
Another central lesson is the importance of co-design with local stakeholders. Consultations with dyehouses, researchers and textile operators ensured that the process responds to real operational constraints, energy realities, and regulatory pressures. This greatly increases adoption potential and demonstrates that WEFE solutions must be both technically sound and industrially practical to succeed.
The demonstrator has high replicability potential across Mediterranean textile clusters, especially in regions with chronic water scarcity (Tunisia, Turkey, Morocco, Egypt). Because the technology is modular, closed-loop and independent of local water infrastructure, it can be deployed in existing textile facilities without major structural changes. This reduces barriers to replication and supports deployment even in areas with weak treatment capacity.
Scalability is also strong: once the TRL6 pilot is validated, the technology can be scaled through standardized CO₂ dyeing units, allowing dyehouses to adopt the system with predictable performance, energy savings, and compliance benefits. The model can also be licensed to regional equipment manufacturers, accelerating widespread adoption.
For policymakers, the main lesson is that WEFE-aligned industrial technologies can directly support national water strategies, reduce energy loads, and protect vulnerable ecosystems. Encouraging such solutions through incentives, green financing, and regulatory alignment could help Mediterranean countries meet future water-energy-environment goals more efficiently.
This demonstrator shows that transforming one industrial process can unlock broad WEFE benefits across entire regions.
