Chapter 5 — full chapter
5.2.1 Water-Efficiency and closed-loop water systems
Water-efficient manufacturing combines low-liquor-ratio technologies, water recycling, process optimisation and wastewater treatment. Closed-loop water systems recover, treat and reuse process water, reducing freshwater consumption while limiting wastewater discharge. Wet processing is one of the most resource-intensive stages of textile manufacturing. Water-efficient dyeing technologies aim to reduce freshwater consumption while maintaining colour quality and process performance. Strategies include low-liquor-ratio dyeing machines, digital colour management, foam dyeing, supercritical CO₂ dyeing, and improved process control to minimise reprocessing and wastewater generation. These technologies contribute to lower environmental impacts while reducing operating costs associated with water treatment and energy use.
Dyeing, printing, washing and finishing are particularly relevant because they can combine high water demand with complex wastewater streams. The amount and composition of wastewater varies according to fibre type, process, machinery and chemical recipe, so there is no single solution suitable for every textile facility (Holkar et al., 2016; Yaseen & Scholz, 2019).
Manufacturers can reduce water demand through approaches such as low-liquor-ratio processing, improved process control, digital printing, foam-based application systems and other low-water colouration or finishing technologies where technically appropriate. Water recovery and reuse can then reduce the demand for freshwater and the volume of wastewater discharged.
The most appropriate technology depends on the fibre, product, production volume, required finish and available infrastructure. A technology should therefore be evaluated not only by how much water it saves, but also by its energy demand, chemical requirements, product quality and ability to operate reliably at industrial scale.
Closed-loop finishing systems are designed to recover, treat and reuse water, chemicals and auxiliary substances used during textile finishing processes. Instead of treating these resources as waste after a single use, circular finishing technologies return them to the production cycle whenever technically feasible.
Typical measures include:
- low-water dyeing technologies;
- closed-loop water recycling systems;
- rainwater harvesting where appropriate;
- wastewater treatment and reuse;
- digital monitoring of water consumption.