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A study on Recycling of Waste Gypsum Using Microbially Induced Calcite Precipitation (MICP)

In this study, to improve the characteristic that the waste gypsum reacts at the high temperature and high pressure when it is recycled, it was intended to develop the waste recycling method under the condition of room temperature and normal pressure. To do that, the calcium ion extraction test, and the mineralogical analysis and the structural analysis of the precipitation by the microbially induced calcite precipitation (MICP) were performed. The optimal calcium ion extraction condition was analyzed as solid-liquid ratio of 1:10, solvent type: HCl and HNO3. In addition, the air injection increased the activation of microorganism increasing the reduction of calcium ion by reaction time. Particularly, the precipitation was generated after MICP and it was confirmed that the precipitation was the calcium carbonate (CaCO3) through the mineralogical analysis and the structural analysis of the precipitation. Therefore, MICP can be utilized as a method to recycle the waste gypsum.