Effective Removal of Selenate from FGD Waste Streams Through the use of Novel Nanocomposite Particles

In coal-fired power plants, the waste streams from flue gas desulfurization (FGD) have high levels of mercury, arsenic, and selenium; therefore, these streams need to be treated prior to discharge. Moreover, the use of non-traditional waters for FGD, combined with more stringent regulations on emissions from power plants, is increasing the concentration of these metals in FGD wastewater. However, the use of cost effective technologies for mercury removal from FGD waste streams is impeded by the fact that selenium is in a selenate form, which is less amenable for removal by conventional adsorption processes. Therefore, a comprehensive low-cost treatment technology, specifically targeted at selenium, is needed. This project will demonstrate the feasibility of a new nanocomposite particle media that simultaneously reduces selenate to selenite in situ, and adsorbs the reduced selenium species. The nanoparticle media will be designed as a drop-in into existing waste water treatment systems. In Phase I, a laboratory scale demonstration of the nanocomposite media will be conducted on both synthetic and actual FGD waters. Phase II will involve a field demonstration at an actual power plant site. Commercial Applications and other Benefits as described by the awardee: The need for this technology is driven by three sources: (1) an increased impetus to use non¬traditional water sources (e.g., mine pool water) for power plant cooling and FGD, which lead to elevated levels of mercury, arsenic and selenium in the waste water; (2) increased regulations on air quality standards, and (3) the need for a low cost process for treating the oxidized form of selenium. Apart from being applicable to FGD waste streams, the proposed technology also should find use in agricultural water treatment and selenium removal from industrial wastewater discharges.