An Investigation on Biological Treatment of Sandy Soil

Due to environmental problems of desert expansion as well as dust storms, looking for more efficient and comprehensive methods to stabilize dune sands seems to be an essential necessity. Microbial-induced CaCO3 precipitation (MICP) is an innovative technique that harnesses bacterial activities to modify the physical and mechanical properties of soils. This method produces calcium carbonate precipitation in the soil pores by fracturing urea in the presence of calcium ions. An important factor in achieving uniform calcite deposition (and hence consistent enhancement of geotechnical properties) throughout the treated soil mass is the protocol adopted to inject the reagents of ureolytic bacteria, urea, and calcium. In this study, an urease microorganism was prepared in the laboratory and injected into cylindrical dune sand samples. After required and appropriate curing time, the samples were subjected to unconfined compression and fallinghead permeability tests. The test results showed a significant strength improvement and the reduction of permeability of the treated samples in comparison with those of untreated soil. The research results verified the capability of the biological treatment of dune sand which may be regarded as a potential technique to control desert expansion and dust storms.