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. 

Selective Removal Target



Reduce Chemical Treatment



risk management



Evaporators and crystallizers



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. 

Coal power plant FGD flue gas desulfurization
Power Plant Cooling Towers

Treating the Blowdown

Saltworks’ offers FGD blowdown solutions including:

  • Flex EDR 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/NF 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 evaporative crystallisers, enabling reliable and cost-effective ZLD.

Find the Right Solution

Every FGD site is different. Some have fly ash and landfill 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 blogs provide more information on FGD water treatment economics. Contact us to start a review of your project.

FGD Wastewater reuse Pilot Plant

FGD Related Products

XtremeRO/NF Brine 


Xtreme Reverse Osmosis device Saltworks Technologies

Next-generation water-maker and brine-concentrator based on reverse osmosis that achieves extreme freshwater recoveries, enabling cost-effective brine management and treatment of challenging organic-laden waters including oil & gas produced waters.

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ScaleSense Real-Time Scaling Ion Sensor

An automated, real-time sensor for saline waters that measures calcium (Ca2+), barium (Ba2+), sulfate (SO42-) ions and silica (SiO2). ScaleSense is robust and corrosion-resistant and functions accurately and precisely, even at extremely high-TDS.


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Flex EDR



Flex EDR stack

Flex EDR is an advanced electrodialysis reversal (EDR) system, leveraging our next generation ion exchange membranes. It requires less pre-treatment, tolerates oils and organics, selectively removes ions and uses fewer chemicals.


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BrineRefine Chemical Softening System

BrineRefine Chemical Softening System

Smart, compact, modular chemical softening system that reduces costs with precision dosing and built-in solids management. Improves recovery and minimizes fouling risk with intelligent controls that communicate with downstream assets, like RO or evaporators.

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FGD Related Resources

Comparison of FGD wastewater, one container is brown, murky and the second is clear water.

Flue Gas Desulfurization (FGD) Wastewater Pilot Test Results

Saltworks completed an off-site Flex EDR 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.

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coal ash pond

Coal Ash Pond Water Treatment: Technology Options

Coal ash pond water may require treatment as leached pollutants from ash pond water pose human health and ecological risks. Consider membrane concentrators, minimal liquid discharge (MLD), and zero liquid discharge (ZLD) technologies to reduce brine volumes from treating leachable pollutants.

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