Abstract

Mixing of semi-dry flue gas desulfurization solids and fly-ash from coal-fired power plants results in a solid waste contaminated by calcium sulphite. Therefore, it becomes useless for industry and is often landfilled. To support decision-making on process configurations to monetize this solid residue a gate-to-gate life cycle assessment was performed, considering three scenarios: Base case–standard 360 MW power plant; Case I –base plant adopting dry thermal oxidation treatment of spray dryer solids; Case II - bypass of desulfurization system. Cases I and II allow commercialization of the solid residue as class C fly-ash. Evaluated alternatives were compared based on quantitative potential environmental impacts, using United States Environmental Protection Agency waste reduction algorithm. Based on the results, the Base case was more aggressive to the environment, due to solid waste production. Case II increased photochemical oxidation and acidification potentials. Case I was the more environmentally friendly but demands additional capital and operational expenditure.