Zero Liquid Discharge

The power industry as well as oil & gas, chemical, petrochemicals, mining and other industries generate large volumes of waste water that must be managed.  Commonly these wastewaters are discharged via a plant outfall to a surface water body, an evaporation pond, or in some cases deep well injected.  However, there are growing environmental concerns regarding such discharge practices, which has resulted in the development of Zero Liquid Discharge (ZLD) processes.

Zero liquid discharge can be defined broadly as a process for maximum recovery of water from a waste water source that would otherwise be discharged.  This water is beneficially reused and the salts, and other solids contained in the waste water are produced and generally disposed of in a landfill.

The drivers for zero liquid discharge include a growing concern by the public about the impact of such discharges on the environment, and in many areas of the world, water is a scarce resource.  Such concern is resulting in increased regulation and limitation of waste water discharges.  Even without regulatory push, many companies in various industries are mandating initiatives for reducing water discharge by recycle reuse, as well as ZLD, to reduce their environmental footprint and improve sustainability.

Zero liquid discharge can be achieved in various ways.  There is no “one size fits all” solution, as the optimal system design is site specific.  The wastewater composition, various streams to be treated, site specific operating costs, footprint availability and other factors are determining factors for an optimal design. Zero Liquid Discharge System, Zero Liquid Discharge Plant, zld system, zero liquid discharge plant, zld plant, zero liquid discharge water treatment system

The system objectives for a zero liquid discharge system are to eliminate a liquid waste water discharge, generate solids for landfill disposal or reuse, and to recycle a high-quality water that can be beneficially reused.  The design objectives are to minimize the capital investment and system operating cost, while not significantly impacting the manpower required for operation.  Further, the system must be designed with operational flexibility to meet the facility needs and be safe and reliable.