Impact of palm oil mill effluent as an economic medium for soil fixation via microbially induced carbonate precipitation

Microbial-induced carbonate precipitation (MICP) has been extensively investigated as a viable biological mechanism for soil fixation and biocementation. However, its dependence on expensive fermentation media for bacterial proliferation is a cause for concern for researchers in this field. This research uses diluted palm oil mill effluent (POME) at various concentrations (20–80%, v/v) for Sporosarcina pasteurii survivability and MICP application. It was revealed that diluted POME at various concentrations achieved OD 600 (biomass production) of 1.13±0.05 to 1.90 ±0.02, and urease activities of 9.70 ±0.46 to 18.07 ±0.45 mM urea hydrolysed/min. The CaCO 3 precipitation increased with increasing molarity (0.25–1.5M) of cementation chemicals (urea and CaCl 2 ). Samples incubated at 10 °C and 50 °C yielded fewer calcium carbonate minerals. Scanning electron microscopy (SEM) revealed that diverse crystal-like forms (such as spherical, pyramidal, and rhombohedral) were present in the MICP-treated soil samples. The elements included in the crystal structures were identified by mineralogy analysis using energy-dispersive spectroscopy (including oxygen, calcium, carbon, and nitrogen). The chemical functional groups and thermal behaviours of the biocemented samples were further evaluated using instrumental studies (Fourier-transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry), demonstrating the promising potential of POME for minimizing the costs of MICP implementation.