The present invention relates generally to the field of emission 
control equipment for boilers, heaters, kilns, or other 
flue gas-, or 
combustion gas-, generating devices (e.g., those located at power plants, 
processing plants, etc.) and, in particular to a new and useful method and apparatus for: (i) reducing the levels of one or more 
gas phase selenium compounds and / or one or more other RCRA metals, or RCRA 
metal compounds (regardless of whether such other RCRA metals or RCRA 
metal compounds are in the 
gas phase or some other phase); (ii) capturing, sequestering and / or controlling one or more 
gas phase selenium compound and / or one or more other RCRA metals, or RCRA 
metal compounds (regardless of whether such other RCRA metals or RCRA metal compounds are in the gas phase or some other phase) in a 
flue gas 
stream and / or in one or more pieces of emission control technology; and / or (iii) capturing, sequestering and / or controlling one or more gas phase 
selenium compound and / or one or more other RCRA metals, or RCRA metal compounds (regardless of whether such other RCRA metals or RCRA metal compounds are in the gas phase or some other phase) in a 
flue gas 
stream prior to desulfurization and / or in one or more pieces of emission control technology prior to one or more desulfurization units,