Enhanced bioremediation of oily sludge using co-culture of specific bacterial and yeast strains

BACKGROUND: Considerable volumes of petrochemical oily sludge can be generated from oil production and processing activities. Total petroleum hydrocarbons (TPH) contained in oily sludge are detrimental to human health and the environment. Thus, oily sludge is classified as a priority environmental pollutant by the US Environmental Protection Agency and it must be treated properly before discharge into the environment. RESULTS: In this study, a functional microbial consortium consisting of Bacillus subtilis, Bacillus megaterium, Achromobacter xylosoxidans, Pseudomonas fluorescens, Candida tropicalis and Rhodotorula dairenensis, isolated from petroleum-contaminated soil, was applied for bioremediation of petrochemical oily sludge in a shake flask and oily sludge microcosm study. These strains utilized the oily sludge as sole source of carbon and energy. The oily sludge contained 21.5% (w/w, dry weight basis) of total petrol hydrocarbons (TPH). Results showed that the microbial consortium exhibited an excellent oily sludge degradation capacity, reducing 92.5% of aliphatics, 79.3% of aromatics, 48.6% of NSO-containing compounds, 31.8% of asphaltenes and 80.6% of TPH, by the end of the 1-year microcosm experiment. In contrast, biodegradation rates of these fractions were 83.3%, 17.5%, 8.4%, 4.7% and 56.1%, respectively, in the non-inoculated treatment. These strains survived well and adapted to the oil sludge environment throughout the incubation period. Dehydrogenase and polyphenoloxidase activity of the oily sludge was remarkably promoted by inoculation of the microbial consortium. CONCLUSION: The results indicated that the microbial consortium has the potential to be used in bioremediation of petrochemical oily sludge polluted environments. (C) 2014 Society of Chemical Industry