Coal-Fired Power Plant Flue Gas Desulfurization Wastewater Treatment

The United States Environmental Protection Agency (USEPA) possibly will revise the effluent limitation guidelines for steam electric power generating units. The revised guidelines may lower discharge limits for various contaminants in flue gas desulfurization (FGD) wastewater including mercury, selenium, arsenic, and nitrate/nitrite. At the Water Research Center, the power industry is evaluating various technologies that may address the new effluent limitation guidelines and promote water conservation. Stringent discharge limits along with water conservation and reuse efforts are two of the major drivers to achieve Zero Liquid Discharge (ZLD). Potential pollutant levels are so low that ZLD may be the best option, if not an outright requirement. A key disadvantage of thermal ZLD is its high capital cost. One way to reduce this cost is to pre-treat the liquid stream using innovative membrane technologies and reverse osmosis (RO).