Zero liquid discharge wastewater treatment technologies

Abstract Zero liquid discharge (ZLD) is a wastewater management strategy that can do away with liquid waste resulting in maximum efficiency of water usage. It is an engineering approach to water treatment where all water is recovered and contaminants are reduced to solid waste. While many water treatment processes attempt to maximize recovery of freshwater and minimize waste, ZLD is the most demanding target since the cost and challenges of recovery increase as the wastewater gets more concentrated. This strategy has attracted worldwide interest in recent years. Although incorporation of ZLD can reduce water pollution and intensify water supply, the technology is constrained by high cost and intensive energy consumption. In this chapter, we discuss the key drivers, incentives, technologies, and environmental impacts of ZLD. We also highlight the different processes adapted so far in view of the ZLD system in wastewater treatment and analyze the pros and cons of the existing and emerging ZLD technologies. The chapter also includes some of the possible environmental impacts of such a strategy along with the prospects of ZLD technologies and research needs.