Assessment of PCDD/F and PBDD/F emissions from coal-fired power plants during injection of brominated activated carbon for mercury control

The effect of the injection of brominated powdered activated carbon (Br-PAC) on the emission of brominated and chlorinated dioxins and furans in coal combustion flue gas has been evaluated. The sampling campaigns were performed at two U.S. Department of Energy (DOE) demonstration sites where brominated PAC was being injected for control of mercury emissions. The results of the sampling campaigns showed that injection of the brominated PAC upstream of the electrostatic precipitator (ESP) did not increase the emissions of total and Toxic EQuivalent (TEQ) chlorinated and brominated dioxin compounds. Rather, the data suggested the sorbent may capture these compounds and reduce their concentration in the flue gas stream. This effect, when seen, was small, and independent of the type of plant emission controls, temperature at the point of injection, or fuel-chlorine content. The addition of the brominated PAC sorbent resulted in slight increases the total content of chlorinated dioxins and furan in the particulate matter (ash) collected in the ESP, but did not increase its overall toxicity.