Effluent Guidelines and Standards for Power Plant Wastewater Discharge

In 2015, the U.S. EPA finalized effluent guidelines and standards for wastewater discharge from steam electric power plants to limit the levels of toxic metals in discharged wastewater. The rule impacts wastewater streams from flue gas desulfurization (FGD), fly ash, bottom ash and other processes and byproducts. The agency released a steam electric reconsideration rule for FGD and bottom ash waste streams in an August 2020 revision.  

Spray drying is a mature technology that was developed over a century ago and is a technology that has existed in the US coal fired power generation industry for over 30 years to remove SO2 from flue gas. In the waste to energy industry, salt dryers are used to treat similar wet FGD effluent to prevent the discharge of wastewater from many plants in the industry. The salt drying technology is expected to transfer into the U.S. coal-fired power generation industry for treatment of FGD wastewater in part due to its success in similar applications.

Technical studies have been done to supplement the existing salt dryer experience and ensure this technology can be implemented successfully. All of this work and experience has led to several B&W salt dryer commercial project evaluations and commercial offerings. 

Salt Drying Technology for Zero Liquid Discharge

For coal-fired power generation applications, B&W's spray dryer offers true zero liquid discharge by using the latent heat of the boiler flue gas to evaporate the entire wet FGD waste stream.

Spray drying is a mature technology that was developed over a century ago and has existed in the coal-fired power generation industry for more than 30 years to remove SO2 from flue gas. In the waste-to-energy industry, spray dryers are used to treat similar wet FGD effluent to prevent the discharge of wastewater from many plants in the industry.

Our spray drying technology has the capacity to transfer into the coal-fired power generation industry for treatment of FGD wastewater, in part due to its success in similar applications.

GEA Niro
, B&W’s partner in spray drying, has installed more than 25 spray dryers worldwide.  Additionally, we've participated in several commercial project evaluations of spray dryer technology in this zero liquid discharge application.

Potential benefits:

• Elimination of wet FGD wastewater discharge
• Allows more time for implementation per Effluent Limitation Guidelines (ELG)
• Uncomplicated process requires limited operator attention while maintaining high reliability
• Option for fabric filter to save fly ash for sale
• Designed for improved material handling

Zero Liquid Discharge

salt drying technology for zero liquid discharge

Project / Case Feature Item

B&W presents a paper on Salt Drying at the International Water Conference 2016.

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