Zero liquid discharge (ZLD) is an ideal condition of a complete closed loop cycle, where release of any liquid effluent is eliminated; it is a remarkable effort of every industry that implements it to meet with the environmental parameter in a challenging way. In the process of achieving ZLD, solids are recovered. Cost-wise, achieving ZLD is a costly proposition but is now becoming necessity because rivers need to be rejuvenated, after recognizing that many industrial sectors are not able to achieve standards and this ultimately necessitates working towards zero liquid/effluent discharge standard. ZLD is applicable to industries having high BOD and COD load, colour bearing effluents, having metals, pesticides and other toxic/hazardous constituents.