A method for reducing acid gases in a flue gas, the method comprising reacting biosolids comprising a scrubbing agent with a flue gas comprising an acid gas, thereby reducing the amount of acid gas in the flue gas is disclosed. Also disclosed is a flue gas scrubbing process comprising: combusting a fossil fuel and biosolids comprising a scrubbing agent, thereby producing a flue gas comprising an acid gas, wherein the flue gas has a reduced amount of acid gas compared with flue gas produced from the combustion of the fossil filet alone. A flue gas scrubbing process comprising providing a stream of biosolids that includes a hydroxide or an oxide of a Group IA or IIA element, providing a flue gas comprising an acid gas, and reacting the biosolids stream with the flue gas so as to reduce the amount of acid gas in the flue gas is also disclosed.