Unusual speciation and retention of Hg at a coal-fired power plant.
An unusual and different speciation of Hg in the outgoing gaseous stream of the flue gas desulfurization (OUT-FGD) system was revealed at two Spanish power plants (PP1 and PP2) equipped with a forced oxidation wet FGD system with water recirculation to the scrubber. At PP1 and PP2, a high proportion of Hg escapes from the electrostatic precipitator in gaseous form, Hg(2+) (75-86%) being the species that enters the FGD. At PP1 Hg(0) (71%) was the prevalent Hg OUT-FGD species, whereas at PP2 Hg(2+) was the prevalent Hg OUT-FGD species in 2007 (66%) and 2008 (87%). The unusual speciation of gaseous Hg OUT-FGD and the different Hg retentions between 2007 and 2008 at PP2 were attributable to the evaporation of HgCl(2) particles from the aqueous phase of gypsum slurry in the OUT-FGD gas and the Al additive used at PP2, respectively. The Al additive induced the retention of Hg as HgS in the 2007 FGD gypsum, thus reducing gaseous emissions of Hg in the OUT-FGD gas.
Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18-26, E-08034 Barcelona, Spain. patricia.cordoba@idaea.csic.es
Patricia
P
Córdoba
M
M
Maroto-Valer
Carlos
C
Ayora
Ron
R
Perry
Manuela
M
Rallo
Oriol
O
Font
Maria
M
Izquierdo
Xavier
X
Querol
D000535:Aluminum / Q000737:chemistry; D002133:Calcium Sulfate / Q000737:chemistry; D003031:Coal; D005740:Gases / Q000032:analysis; D008628:Mercury / Q000302:isolation & purification*; D044367:Phase Transition; D011210:Power Plants; D013455:Sulfur / Q000302:isolation & purification; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000302:isolation & purification
D003031:Coal; D005740:Gases; D014874:Water Pollutants, Chemical; D013455:Sulfur; D000535:Aluminum; D008628:Mercury; D002133:Calcium Sulfate