Wiped film evaporator or thin film evaporator plants can be effectively used for multiple applications in wastewater treatment: to produce clean water for reuse or recycling, based on the minimum or zero liquid discharge (MLD, ZLD) approach; to concentrate wastewater prior to off-site disposal reducing its volumes and costs; to produce, if necessary, a dry solid waste.
The following streams are separated using evaporation:
- A condensate, free of salts, metals, high boiling point organics, that in most cases can be reused or recycled
- A concentrate for off-site disposal or recovery
Wiped film evaporators (WFE) or thin film evaporators (TFE) and wiped film dryers (WFD) are optimally suited to handle very high viscous and fouling streams: a very challenging or even impossible task for other types of heat exchangers. As a consequence, they are often used in the final stage of ZLD and MLD wastewater treatment plants.
Combining natural circulation or forced circulation evaporators, used in prior concentration stages, provides the best balance in terms of investment, operating costs and performances, especially when a solid waste is required.