Oily sludge degrading potentials of single and consortium of autochthonous bacterial species

Oily sludge (OS) degrading potentials of single and consortium autochthonous bacterial population was carried out using standard analytical procedures. Three autochthonous bacterial species; Pseudomonas aeruginosa, Bacillus cibi and Bacillus subtilis were associated with the OS. The isolates exhibited varying OS utilizing and biosurfactant producing potentials. P. aeruginosa was the best OS utilizer while B. subtilis was the best biosurfactant producer (emulsification index of 15.6%). Degradation of the OS with single culture of the best OS utilizer (P. aeruginosa) and consortium of the best OS utilizer and best biosurfactant producer (B. subtilis) revealed that the consortium exhibited a remarkable potential to reduce the total petroleum concentration in the OS from 100.73 ppm to 41.39 ppm (58.91% degradation) as compared to 51.74 ppm (48.7% degradation) achieved by the single culture. The saturated fraction of the OS was the most susceptible to degradation followed by the aromatic faction while the NSO and asphaltene fraction were the least degraded. P. aeruginosa was able to reduce the saturated hydrocarbon content in the OS by 87.4% while a 95.5% reduction was recorded for the consortium. Similarly, the concentration of PAH in the OS was reduced from 27.94 ppm to 16.74 ppm by the single culture and 12.75 by the consortium. The potentials of these bacterial communities can be explored for broader use in remediating oily sludge contaminated soil as well as managing oily sludge waste in the oil and gas industry.