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.