Fixation of Carbon Dioxide and Calcification of Waste Concrete Using Coccolithophorid Algae in Seawater

摘要

The fixation of carbon dioxide and calcification for calcium carbonate from waste concrete were investigated by incubating coccolithophorid algae (Gephyrocapsa oceanica) in seawater with Ca(HCO_3)_2 solution which was dissolved excess calcium ion by streaming carbon dioxide through seawater with nutritive salts. This process was more effective to soft chemical reaction utilizing nature energy for resource recycling of waste concrete. Cell concentration of coccolithophorid algae and amount of fixed calcium carbonate as coccolith were determined by meaning optical microscope, scanning electron microscope and elementary analysis. The optimums for growing of Gephyrocapsa oceanica in seawater with nutritive salts were pH of 8.1 approx 8.5, cell concentration of 40 approx 60 X 10~4 cell cm~(-3) and light/dark cycle of 12 h/12 h. The concentration of carbon dioxide passed through the seawater for dissolving waste concrete was effective at 5 approx 20 vol percent. Utilization of seawater with together nutritive salts and excess calcium ion was promoted growth of coccolith on surface of Gephyrocapsa oceanica and number of coccolith pieces. This result was caused by dissolving excess amount of calcium ion in the seawater.