Zero Discharge Desalination Technology: A High-Recovery Reduction of Brine Disposal for Inland Desalination

Abstract

By 2025, nearly one-third of the world's population will face severe water scarcity. Many locations that have inadequate freshwater supplies are fast-growing regions, including the American Southwest, Florida, and Asia. In the United States, the economic future of the arid Southwest will demand a combination of water conservation, recycling, and “new water” creation. One source of new water is desalinated brackish surface water and groundwater. Reverse osmosis (RO) membrane technology provides high salt rejection at relatively low operating pressures, but freshwater yield is constrained by the presence of soluble salts. Brine management strategies typically first consider zero liquid discharge technologies followed by crystallization. However, the cost and energy use required for these processes often render them cost-prohibitive for desalination. The most common concentrate disposal methods—evaporation ponds, deep-well injection, and water hauling—have their own disadvantages, including a requirement for large areas of land, regulatory limitations, and costs. This article explores use of alternative recovery technologies to reduce brine and increase water recovery.