For removal of industrially produced CO2, we have proposed a new CO2 fixation method which is combined with artificial weathering of waste concrete and coccolithophorid algae cultures. Waste concrete was suspended in sea water and weathered efficiently by supplying CO2 to the suspension. During this weathering process, CO2 was absorbed and dissolved into sea water. The maximum CO2 absorption by the concrete suspension (100 g/l) was obtained as 1.5 (g CO2)/l for 1 hr. Calcium contained in waste concrete was also dissolved in sea water. Coccolithophorid alga Emiliania huxleyi was cultured in a medium which was composed of the resulting sea water and contained sufficient dissolved inorganic carbon. Coccolith production and growth using this medium were enhanced to a greater extent than using Eppley's medium. During E. huxleyi culture, atmospheric CO2 was absorbed, and dissolved inorganic carbon was fixed in CaCO3 particles. These results demonstrate that atmospheric CO2 can be absorbed and fixed permanently in the form of calcium carbonate and biomass by artificial weathering of waste concrete and coccolithophorid alga culture.
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