Comparison of Bacterium and Microalga in Biological Improvement of Copper Mine Tailings

Cementation of soil using calcium carbonate precipitation or MICP is a new biologic method of soil improvement. In this research, this method was used to improve the strength of copper mine tailing slurry. It has been performed by carbonate producer microorganisms, which by adding the appropriate calcium source, cause sedimentation or biocementation in the environment. The resulting calcium carbonate has a significant effect on the soil strength. In this study, a bacterium called Sporosaurina Pasteurium and a microalga called Chlorella Suloxanase, have been used. Optimization of the calcium carbonate formation in the presence of the most suitable calcium chloride concentration and the best temperature for the reaction has been evaluated. The calcium carbonate was injected into the specimen and the sample strength was determined by unconfined compression tests. After biological treatment, the unconfined strength of the slurry increased up to 3 times for saturated state and 7 times for the dry condition which proved the successful treatment using biological method.