English

Abstract

Carbon dioxide and calcium oxides may be used to neutralize acidic lakes. In lignite producing areas combustion power plants producing CO2 are often close to pit lakes. If fly ashes from these power plants could be used as calcium oxide source, carbonate precipitation in lakes could as also as a mineral trap to dispose of CO2. In a preliminary step the feasibility of this treatment scheme is investigated and includes a model based assessment of expected effects on the surface water, the reactivity of the chemical components, and the technical prerequisites. A pit lake in the Lausitz (Lusatia) post mining area in Germany was chosen as a test site, where fly ash has been deposited for more than 25 years. The feasibility of re-suspending these deposits to neutralize the lake was demonstrated in the years 2000 and 2003, and additional CO2 is proposed to increase the buffering capacity of the lake water, to precipitate, and store carbonates in the lake sediments.