Zero liquid discharge (ZLD) refers to systems that enable absolute recycling of treated wastewater and conversion of dissolved solids into solid residue through concentration and thermal evaporation. ZLD certification is based on water consumption, wastewater recycled, and solids recovered. Conventional ZLD uses multi-effect evaporation, but this requires high steam consumption. A new technology called polymeric film evaporation uses polymer films as the heat transfer surface, achieving lower operating costs than multi-effect evaporation through reduced steam and power usage. This polymeric film evaporation technology provides benefits like low maintenance and scaling resistance.