Chapter 13 - Necessity driven implementation of zero liquid discharge in textile and fertilizer industries toward sustainability—Indian scenario

Abstract

Zero liquid discharge (ZLD) is a wastewater management strategy that has become beneficial and a necessary option in the recent years for obviating water scarcity and water pollution problems by eliminating the generation of liquid waste. In this chapter, the importance of ZLD along with challenges which are faced in the development and implementation of ZLD are discussed with reference to different treatment schemes adopted in textile and fertilizer industry to achieve ZLD in context to Indian scenario. The ZLD scheme to be adopted depends on the effluent characteristics and the raw materials used in the process. Because of the employment of variety of chemicals for the textile fabric treatments, the effluents from textile industry contain refractory organics and inhibitory compounds with color. The degradation of such compounds by conventional biological treatment is ineffective due to the presence of lower biological oxygen demand (BOD)/chemical oxygen demand (COD) ratio. The nitrogenous and phosphatic fertilizer industry effluents majorly contain pollutants such as ammonia and ammonium salt; nitrates; urea; chromate, phosphates, cyanides and sulfides; BOD; fluorides and suspended matter. The thermal processes of evaporation–crystallization with multiple effect evaporator and membrane technology approach, mainly involving the reverse osmosis, are the important components of ZLD system. The future scope of ZLD can focus on the development of advanced technologies that consume low energy with cost-effective benefits. Continued efforts of the scientific community in developing sustainable technologies for ZLD, appropriate and frequent checks by the regulatory bodies along with responsible approach of the industrial organizations in implementation of ZLD may only drive the society toward sustainable development.