Chapter 1 - Concept of zero liquid dischare—present scenario and new opportunities for economically viable solution

Abstract

Water scarcity, water utilization, and water regulations are the challenges faced by industries. Zero liquid discharge (ZLD) is a wastewater management strategy to recover almost 100% of the water for reuse, thus eliminating any liquid waste leaving the industrial facility and allowing the resource recovery. The ZLD market is growing with enforcement of stricter and stringent environmental regulations. Many industries are volunteering to reduce water discharge through recycle/reuse by initiating the implementation of ZLD, and improve the sustainability by reduction of the environmental footprint. This chapter presents the need for ZLD, the conventional and recent technological developments and practices to achieve ZLD with a focus to minimize the cost and energy requirements. The chapter discusses the various thermal processes for ZLD along with the improved technologies for thermal ZLD to handle the corrosion and temperature-related problems and the operating cost of the treatment. The membrane-based preconcentration steps like reverse osmosis, forward osmosis, electrodialysis/electrodialysis reversal and membrane distillation, and combination of the membrane processes prior to the thermal ZLD to improve the water recovery are discussed. The technologies and designs offered by various key ZLD players in the global ZLD market are discussed. The chapter concludes with a note that the goal toward the economical realization of ZLD may only be met by partnering efforts of researchers, industry, and the companies which are the key players in ZLD market. ZLD should not remain as a myth or enforced necessity, but must be embraced willfully by the industries as a corporate social responsibility (CSR) activity.