The HPD system will use a two-step process to treat effluent from the FGD scrubbers to provide a zero liquid discharge (ZLD) solution as mandated by ENDESA Italia, since no aqueous waste is allowed. The first step involves pre-treatment of the purge stream using clarification and softening to reduce suspended solids, calcium, magnesium, and heavy metals. The second step involves the use of a two-stage evaporation and crystallization system. In the first stage, falling film evaporators concentrate the stream and recover quality water for reuse in the plant. The brine is further concentrated in the second stage brine crystallizer and more quality water is recycled back into the facility., A solid, non-hygroscopic salt cake is discharged from the ZLD system for proper disposal
HPD was chosen for this project based on its overall expertise in the design of zero liquid discharge (ZLD) systems in several industries and its specific experience in the power industry.