Name and briefly describe two technologies used to reduce PM and SO2 emissions from coal-fired power plants.

• A. Biomass co-firing and selective catalytic reduction.
• B. Flue gas desulfurization (scrubbers) remove SO2; Electrostatic precipitators or baghouses capture PM before release.
• C. Catalytic cracking and hydroprocessing remove PM and SO2.
• D. Membrane separation removes both PM and SO2.

Answer: (B)

Coal-fired power plants emit both fine particles (PM) and sulfur dioxide (SO2). Controlling these pollutants typically involves treating the flue gas in separate steps. Flue gas desulfurization, or scrubbers, remove SO2 by bringing the exhaust into contact with a sorbent like limestone slurry, which reacts with the gas to form a solid waste such as gypsum. For particulates, electrostatic precipitators use an electric field to charge and attract fine particles (fly ash) to collection plates, while baghouses trap particles in fabric filters before the gas is released. This combination directly targets the two pollutants produced by coal combustion, making it the best description. Other options mix in technologies aimed at different pollutants or processes not used for flue-gas cleaning in coal plants.