Desalination systems for minimal and zero liquid discharge purposes: A review

Abstract

Freshwater reserves are being depleted as a result of natural and production processes, including industrialization, agriculture, and rapid population growth. Water scarcity can be effectively compensated for with various desalination techniques. However, the release of high concentrate brine from the desalination systems is the major environmental concern. As such, minimal or zero liquid discharge (MLD or ZLD) desalination techniques are vital for high water recovery and zero waste production. This study aims to review recent literature on the use and management of brine from various sectors of brine production and seawater desalination industries using MLD and ZLD technologies. Thermal, membrane, and hybrid desalination systems are also reviewed with a focus on highlighting the operating principles, advantages, and challenges. It can be concluded that hybrid systems have the lowest specific energy consumption (SEC) and cost compared to membrane and thermal systems. Multi-effect desalination/multi-stage flash (MED-MSF) has the lowest SEC of 1.107 kWh.m⁻³ and a water recovery of 98 %. Furthermore, ZLD desalination systems consume less energy when pretreatment techniques are applied before the thermal process. The hybrid MD-MSF-Cr process has the lowest cost with a cost of 0.62 $.m⁻³ (with a water recovery of 89 %).