Optimization of growth medium for microbially induced calcium carbonate precipitation (MICP) treatment of desert sand

Wind-induced sand erosion is a natural process, and can have several negative impacts on human health, environment, and economy. To mitigate the wind-induced sand erosion, an environmental friendly technique that helps to bind soil particles is desirable. The microbially induced calcium carbonate precipitation (MICP) treatment has lately become renowned and a viable alternative to enhance the binding of sand particles (especially against wind erosion). The efficiency of Sporosarcina pasteurii bacteria in inducing calcite formation can be influenced by various factors, including the type of growth media used for bacterial culture. Most of the studies have mainly validated the efficiency of S. pasteurii bacteria usually under single growth media for the MICP treatment. However, the efficiency of S. pasteurii under different growth media on calcite formation is rarely explored. The current study explores the effect of S. pasteurii bacteria on calcite formation under the presence of three different growth media, namely, molasses (MS), tryptic soy broth (TB), and nutrient broth (NB). The three growth media have been applied in the laboratory with and without bacterial solution (control samples). Altered cementation media concentrations (0.5 and 1.0 M) with different pore volumes (PVs), namely, 0.25, 0.50, and 1.00 PV were used in sand-filled tubes for 7 and 14 treatment cycles (1 cycle=24 h). The pH and EC were measured for 12-h period in every 2 h interval, to monitor values at the time of treatment at room temperature. The calcite precipitation was confirmed using SEM (scanning electron microscope), PXRD (powder X-ray diffraction), and calcimeter tests. It was observed that MS generates lower calcite precipitation as compared with NB and TB. However, MS has the advantage of being more economical and abundant (waste product from sugar mills and refineries) as compared with other growth media (NB and TB). It was observed that the minimum and the maximum calcite precipitation using MS is 5% and 12%, respectively. The findings using MS in the present study was compared with the literature and found that precipitation of calcite using MS is effective to stabilize soil against wind erosion.