Zero Liquid Discharge (ZLD) Technology overview

Zero Liquid Discharge (ZLD) is an industrial process which does not release any wastewater. This target is commonly achieved by separating streams into evaporation or crystallization paths. During these processes, contaminated elements are discharged as solid waste whilst the condensate is recovered. Typically, the effluent is a salty solution and the thermal separation is the final step of ZLD, after being exposed to pre-treatments, ultrafiltration and reverse osmosis units.

ZLD technology has characteristic advantages on wastewater concentrations:


  • No wastewater discharge leaves the plant. Only solid wastes are produced and they are disposed of appropriately.
  • Volume reduction of the effluent can be maximized with a water content of up to 1-3% of water content. This results in low disposal costs.
  • The condensate, otherwise known as distillate, can be recycled as process water.

Our evaporation and crystallization systems commonly operate under vacuum and can be designed for single-duty or multi-purpose operation. They optimally combine the following technologies:

Falling Film Evaporators

This technology is particularly suited for energy-saving, multiple-effect evaporation and mechanical vapor re-compression processes. It only requires a very small operating temperature and thus allows it to be easily controlled and fast to start up and shut down due to a minimal liquid hold-up. Falling film technology is the right solution for streams which are viscous in nature and contain small concentrations of suspended solids. A falling film evaporator can be used as a pre-concentrator in a combined multiple-effect plant. It has the capacity to treat streams with small to large flow rates.

Thin Film Evaporators/Dryers
These devices are mostly used when strong sludge dewatering or drying is required. They can be used to achieve a water content of less than 5%. Like the falling film evaporators, this technology is easy to control and fast to start up and shut down due to a very low liquid hold-up. Thin film technology is the right solution for scaling products and for highly viscous fluids. A thin film evaporator can be used as a high-concentrator in a combined multiple-effect plant. It has the capacity to treat streams with small to medium flow rates.

Forced Circulation Evaporators

Due to the high circulation flow-rate and evaporation external to the heat exchanger, forced circulation technology is the right solution for highly viscous streams containing a large concentration of suspended solids, fouling products. A forced circulation evaporator can be used as a high-concentrator in a combined multiple-effect plant with a mechanical vapor recompression arrangement. It has the capacity to treat streams with medium to large flow rates.

Energy saving

3V Green Eagle always tries to apply techniques which minimize energy consumption for its evaporation plants. Some of the methodologies we apply include:

  • Multiple effect arrangement (ME)
  • Thermal vapor recompression (TVR)
  • Mechanical vapor recompression (MVR)
  • Usage of waste energy

Our ZLD plants can be supplied as a skid-mounted unit or are suitable for on-site installation.