A Research of Reservoir Sediment Solidification Using Biotechnology

Abstract

At the end of 2010, almost all reservoirs in Taiwan have sedimentation problem. Sedimentation in major reservoirs, such as Wushoh reservoir, had reached 63.73% of its storage capacity in 2009, and must undergo dredging. However, agencies responsible for the final processing stages of reservoir sediments failed to come up with a breakthrough. Limitations established by environmental protection laws also hindered proper dredging of the reservoirs. Hence, further investigation was required for solidifying and reusing reservoir sediments. This research focused on the reuse of Wushoh reservoir sediments. Experimental results showed that when bacteria Bacillus Pastuerii(B.P.) was utilized in sediment solidification, higher bacterial concentrations could induce higher sedimentation of calcium carbonate. In a 70% Urea-CaCl2 medium, a bacterial concentration of 100% resulted in the highest compressive strength that was 30% higher than the control group (bacterial concentration of 0%). Therefore, bacteria can be used to solidify sediments and improve compressive strength. In specimens treated with higher concentrations of bacteria, more square and polygonal crystals were observed via SEM. X-ray powder diffractometer (XRD) analysis showed that bacteria-treated sediments contained calcium carbonate crystals in every stage of processing. Hence, it was shown that bacteria can promote solidification by inducing calcium carbonate sedimentation.