Concentrate management technologies for desalination processes leading to zero liquid discharge: Technologies, recent trends and future outlook

In order to equilibrate the global clean water supply and demand stress, the application of both thermal and pressure-driven membrane processes results in the generation of an enormous volume of concentrated waste stream as a by-product. This waste stream which is known as brine or concentrate needs to be disposed of. Owing to the massive volume of concentrate, and stringent discharge regulations, the desalination plant operators are facing unprecedented challenges that call for adopting different approaches to brine concentrate management. This article presents a comprehensive literature review on the zero liquid discharge (ZLD) systems for desalination industry. Major components of both high-recovery and ZLD technologies have been reviewed and presented based on their advantages, disadvantages, capital investment, operation and maintenance costs to help enable industrialists, researchers, engineers and technicians to compare and identify the appropriate concentrate management technology. In addition, beneficial uses and final disposal technologies for brine have been briefly described. Finally, current and future research trends related to concentrate management strategies and possible improvements in ZLD technologies are highlighted.