Author(s): Salwa AlThawadi
BioCementation technology depends on the consolidation of sand particles by using pure microorganisms (B. pasteurii) under complete sterilization conditions during the cellular growth. In this study, an enrichment culture of ureolytic bacteria was used to precipitate aggregates of calcite in-situ under non-sterile conditions. Those bacteria were enriched in the presence of 3 M urea. Soil sample was collected from agricultural fields in Sakhir, Bahrain. Then they were used to precipitate calcite in-situ and consolidate sand particles in the presence of high concentration of 1 M equimolar urea and calcium ions. Continuous feeding of cells was applied. Optical microscope, SEM, EDS, XRD and XRF examinations revealed that this impure bacterial culture resulted in precipitating aggregates of calcite nanoparticles in spherical arrangement in-situ which consolidate packed sand column. Natural competence between bacteria in the enrichment culture did not affect their ability to precipitate calcite nanoparticles and strengthen the sand without interfering with the hydraulics of the treated sand. Therefore, cost of BioCementation technology can be lowered due to the enrichment of local bacteria under non-sterile conditions.