Flue Gas Desulfurization

Treatment for reuse and recovery of FGD wastewaters

Flue gas desulfurization (FGD) systems are used to remove sulfur dioxide (SO2) air emissions in coal-fired power plants. FGD wastewater is often saturated with calcium sulfate, while containing both metals and chlorides. Saltworks can help to boost FGD water cycles through selective chloride removal, or treat the FGD wastewater to zero liquid discharge.

FGD Wastewater

FGD systems remove SO2 from flue gas in power plants. Water used in the process is usually recycled internally, but needs to be purged when chloride concentrations exceed a set level. Accumulating chlorides are the root cause of FGD blowdown wastewater: they decrease sulfur absorption in the scrubber and add corrosion risk.  Blowdown wastewater can have a chloride concentration between 10,000 mg/L and 30,000 mg/L.


Saltworks has novel and conventional solutions for FGD water. We can help you to assess all options, from selective chloride removal up to full stream treatment and ZLD solutions.

Photo of a coal power plant requiring flue gas desulfurization
Photo of cooling towers in a power plant facility

Treating the Blowdown

Saltworks’ offers FGD blowdown solutions:

  • FlexEDR Selective provides a step change in FGD wastewater treatment cost reduction, reducing blowdown by up to 90%. It uses monovalent electrodialysis reversal (mEDR) to selectively remove chlorides, enabling FGD water to be recycled internally without the expense of soda ash and full stream treatments.
  • BrineRefine uses automated chemical softening to remove metals and fluorides from FGD wastewater. BrineRefine was developed to partner with downstream reverse osmosis assets by avoiding coagulants that can damage RO membranes and producing a 0.1 µm filtered RO-friendly fluid.
  • XtremeRO uses advanced process and controls to produce a clean permeate and a brine reject at up to 130,000 mg/L, minimizing evaporative crystallizer costs.
  • SaltMaker is our line of robust evaporators and crystallizers, enabling reliable and cost-effective ZLD.

Find the Right Solution

Every FGD site is different. Some have fly ash and landfill capacity readily available, making high recovery membrane systems such as mEDR attractive by avoiding calcium removal via soda ash treatment and more costly evaporative crystallizers. Other sites may seek full-stream treatment via hybridized chemical softening, reverse osmosis and evaporative processes.


Our articles provide more information on FGD water treatment economics. Contact us to start a review of your project.

Photo of a pilot plant used to treat FGD wastewater for reuse

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Related Resources

A photo of a Saltworks FlexEDR pilot plant operating on-site at EPRI

EPRI Publishes Report: Successful FGD Industrial Water Reuse

Saltworks welcomes a new report by the Electric Power Research Institute (EPRI) summarizing results from a pilot completed at a large coal power plant in the US. FlexEDR monovalent electrodialysis reversal treated FGD wastewater, recovering 93% freshwater.

Photo comparison of FGD wastewater, one container is brown, murky and the second is clear and colorless water.

Flue Gas Desulfurization (FGD) Wastewater Pilot Test Results

Saltworks completed an off-site FlexEDR Selective pilot test to treat flue gas desulfurization (FGD) wastewater from a coal fired power plant in China. The objective was to reduce chlorides such that the FGD wastewater could be internally recycled and final treatment costs reduced notably.