Bacterail Calcium Carbonate Precipitation in Peat

Abstract

Bacterial calcium carbonate precipitation has been used to improve strength and permeability of granular soil. Indeed, very encouraging results have been obtained. Commercially available bacteria have been used in this treatment method. This laboratory scale work is aimed to investigate the feasibility of this new improvement technique in peat that has low strength and high compressibility. For this purpose, two-stage works were carried out. In the first stage, isolation of calcite precipitating bacteria from local soil has been investigated. In the second stage, bacteria have been induced into the peat with treatment solution. The amount of precipitated calcite was determined at the end of the treatment. A preliminary direct shear test has been performed on treated and untreated sample to observe the effect of calcite precipitation on shear strength of the peat. Test results have demonstrated that ureolytic and calcite precipitating bacteria could be isolated from local soils. The treatment has indicated that solid calcite particles precipitated in the peat were nearly 16 % by weight. The shear strength test results have shown that precipitated calcite caused cementing effect on the peat particles.