CaCO₃ precipitation in selected bacteria mixture by activated microbial induction

Activated microbial induction of CaCO₃precipitation (AMICP) is a niche with innovative approaches that involves the exploration of bacterial attacks towards the alteration/transformation of the physical properties of soils. A handful have been documented on this technology in developed countries however, much is yet to be understood in developing African countries like South Africa, just as vermicomposting and waste water treatment technologies are gaining grounds. It is widely known that AMICP by urea hydrolysis in natural soils is possibly affected by contacts between ureolytic and non-ureolytic bacteria, the study explored a designed and experimental assessment of the relations between ureolytic and nonureolytic bacteria and their interactive effects on AMICP. Through existing studies an artificial leveled groundwater medium was injected with model species of bacteria i.e., ureolytic species Sporosarcina pasteurii and the non-ureolytic species Bacillus subtilis. The control treatment was inoculated with a pure culture of S. pasteurii under measurements of pH, optical density (OD), development of NH₄-N, dissolved calcium (DC) and dissolved inorganic carbon (DIC). Outcomes revealed DC precipitated as CaCO₃slower in the control mixture than in the mixed culture irrespective of unfavorable conditions in the mixed culture, i.e., lower concentrations of pH and CO₃ ^2-. Higher density of bacterial cells in the mixed culture resulted from B. subtilis showing significant higher growth rate than S. pasteurii. Previous authors indicate that the presence of the non-ureolytic bacterial species, B. subtilis, stimulate AMICP process through supply of nucleation sites in the form of non-ureolytic bacterial cells.