The total or partial recovery of industrial wastewater (Zero Liquid Discharge, ZLD) is a key strategy for sustainability and efficiency in water management. This approach aims to minimise or completely eliminate liquid discharges, enabling the reuse of treated water in production processes. Traditionally, ZLD systems relied heavily on evaporators and crystallisers, which are energy-intensive and costly technologies. However, thanks to advances in membrane processes, it is now possible to achieve high recovery rates whilst minimising the use of evaporators and optimising operating costs.

Membrane technologies, such as reverse osmosis (RO), nanofiltration (NF) and electrodialysis (ED), enable the removal of contaminants and the concentration of dissolved salts with lower energy consumption than thermal processes. The use of ultrafiltration (UF) as a pre-treatment reduces the risk of fouling and extends the operational life of the membranes, ensuring more efficient performance. Thanks to these advanced systems, water recovery of up to 95% can be achieved, limiting the use of evaporators solely to the final treatment of the most saline concentrates.
These technologies are used in various industrial sectors, such as wastewater treatment in the pharmaceutical, textile and chemical industries, and in energy production. Furthermore, integration with biological or adsorption processes allows for a further improvement in the quality of the recovered water.

The adoption of membrane-based ZLD systems offers significant environmental and economic benefits: a reduced water footprint, lower energy consumption compared to evaporators, and reduced costs associated with the disposal of liquid waste. Against a backdrop of increasing water scarcity and ever-stricter environmental regulations, these solutions represent a crucial step towards a more sustainable and efficient industry.