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

Abstract

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. © 2014 Society of Chemical Industry

Biodegradation of heavy oily sludge by a two-step inoculation composting process using synergistic effect of indigenous isolated bacteria

“…Kamyabi et al [13] also reported that an additional 20% of pyrene removal was achieved by combined cultures in comparison to individual cultures. Other studies have also described the higher ability of consortium to degrade petroleum pollutants [18,39]. The negligible TPH removal (3.8%) observed in the control reactor (A5) indicated that the bacterial populations were responsible for hydrocarbon degradation in the reactors A1-A4.…”

“…Hence, these two strains presented the synergistic effect for TPH biodegradation when they are used in the mixed culture. Several authors [18,35,36] already reported that pure single strains were not able to degrade crude oil effectively compared to their consortium. The positive effects of bacterial consortium compared to individual strains will be deeply discussed in section 3.3.1.…”

“…Hence, one of the most important problems of petroleum hydrocarbons biodegradation has been the lack of effective scale-up of mineralbased medium (MBM) results to full-scale bioremediation methods [17]. For this reason, the appropriate combination of native bacterial species and investigation of their metabolic characteristics and interactions should be performed to optimize and scale-up MBM experiments to full-scale bioremediation processes [18,19].…”

Harnessing plant-bacteria-fungi interactions to improve plant growth and degradation of organic pollutants

“…Bacterial-fungal co-cultures can also enhance bioremediation of petroleum hydrocarbons (Zanaroli et al 2010;Li & Li 2011;He et al 2014;Qiao et al 2014;Ma et al 2015). Li & Li (2011) revealed that co-inoculation of hydrocarbon polluted mangrove sediment with Cunninghamella echinulate and Vibrio rumoiensis led to a more efficient petroleum hydrocarbons bioremediation than the sum of the individual degradations obtained in axenic cultures of the fungus or bacterium.…”

Biosurfactant production for enhancing the treatment of produced water and bioremediation of oily sludge under the conditions of Gachsaran oil field

“…In oil fields, hydrocarbon contamination is an inevitable problem during the upstream operations of the petroleum industry, which can poses significant ecological risks . Every year, billions of barrels of produced water and thousands of tons of oil‐contaminated soil are generated in the oil fields.…”