Zero Liquid Discharge (ZLD)
Zero Liquid Discharge (ZLD)
ABSUN PALAYESH Engineering Company offers complete thermal and non-thermal ZLD solutions to manage tough-to-treat wastewaters. Zero-liquid discharge (ZLD) is a water treatment process in which all wastewater is purified and recycled; therefore, leaving zero discharge at the end of the treatment cycle. Zero liquid discharge is an advanced wastewater treatment method that includes ultrafiltration, reverse osmosis, evaporation/crystallization, and fractional electro-deionization. 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 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 waste water composition, various streams to be treated, site specific operating costs, foot print availability and other factors are determining factors for an optimal design.
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.
:Applications
- Cooling tower blowdown in heavy industry and power plants
- Ion exchange regenerative streams particularly in food and beverage processing
- Flue gas desulfurization, wet wastewater stream
- Municipal potable water systems, wastewater streams
- Process water reuse from agricultural, industrial and municipal streams
- Various industrial wastewater streams from the textile, coal-to-chemical, food and dairy or battery industries
:Advantages
- Minimizes wastewater discharge.
- Maximizes water recovery.
- Creates a valuable product for sale and further processing.
- Removes many environmental issues.
- Reduces dependence on local water sources.
- Significantly reduces the risk of sanctions within the legislative standards for discharged waste.
:Related Technologies
- Falling Film Brine Concentrators
- Forced Circulation Crystallizer
- Horizontal Spray Film Evaporator
- Hybrid Systems with Membrane Pre-Concentrators
- Biological Treatment
- Solids Waste Handling