'Bugs' Used to Treat FGD Wastewater

摘要

Treatment for the wastewater produced by power plant flue gas desulphurization (FGD) systems (also known as scrubbers) is essential because scrubbers generate substantial amounts of effluent that must be retained and treated before it can be released to streams, lakes or rivers. A new approach has been successfully implemented at four North Carolina power plants that use a biological reactor system to increase selenium removal to levels not achievable by existing scrubber wastewater systems. Duke Energy and Progress Energy cooperated with each other in helping test the system and integrate the technology to meet North Carolina environmental standards. In a typical FGD wastewater treatment system, water is pumped to a reaction tank where alkali is added for pH adjustment and gypsum desupersaturation of the wastewater. Recycling seed sludge from the downstream clarifier provides nucleating sites for crystal growth and aids in the desupersaturation process, important in preventing or reducing scale from forming on downstream equipment.