Investigations on the characterizations, optimization and effectiveness of goat manure compost in crude oil biodegradation

Abstract

This study investigates the potential of ready to use goat manure compost (GMC) in the biodegradation of crude oil (CO). Microbial respiration (CO₂ evolved), and heterotrophic bacteria count (HBC) in the CO contaminated soil treated with goat manure compost (COCS-GMC) were also investigated. The HBC demonstrated that the COCS-GMC contained valuable microbial populations while the CO₂ evolved in COCS-GMC and control samples were 500 ​mg ​g−1 and 230 ​mg ​g−1, respectively. The characterization of the CO showed that the dormant hydrocarbon compositions were saturates with traces of aromatic hydrocarbon, resins and asphaltene. The one-way analysis of variance (ANOVA) and Tukey's post-hoc analysis revealed that the CO₂ evolved within 30 days of incubation was significant (P ​< ​0.05) while the CO₂ evolved within 10, 20, 40, and 50 days were not. Instrumental analysis such as the XRD, FTIR and SEM were carried out on the GMC to give further information on the surface morphology and elemental compositions. The results obtained from the RSM indicated the satisfactory performance of the quadratic model with R2 (0.9779), adjusted R2 (0.9621), and predicted R2 (0.8951). The solution selected from the numerical optimization process was CO concentration of 63 ​g ​L−1 and pH 6 with the desirability of 1.