16 - Zero liquid discharge and minimal liquid discharge strategies for sustainable saline wastewater (brine) management and valorization

Abstract

Water is an essential component of the industry. Industrial operations are being forced to decrease their impact on freshwater supplies as this commodity grows increasingly scarce. The proper management of saline wastewater (brine) allows them to lower their freshwater withdrawal while also recovering valuable raw materials. In addition, rising environmental requirements to reduce wastewater discharge from industrial operations into the environment has resulted in the establishment of laws and legislation that support the zero liquid discharge (ZLD) approach (up to 100% freshwater recovery and salt/mineral recovery). The ZLD strategies should be viewed in the context of total water integration of industrial plants to achieve a targeted reduction in water footprint through sustainable recycling and brine valorization. Apart from ZLD, the minimal liquid discharge (MLD) approach has lately sparked interest due to lower capital costs and energy needs than ZLD, with a freshwater recovery aim of up to 95%. The objective of this chapter is to present the latest approaches in brine management. Initially, the brine discharge methods and the negative environmental impact of brine discharge are presented. Subsequently, the recent approach in brine treatment/valorization via MLD and ZLD systems is analyzed, while the stages/technologies used in MLD and ZLD systems are also assessed.