Design and characterization of a bacterial consortium for the degradation of diesel-based drilling cuttings

Abstract

The oil industry frequently generates large volumes of waste, such as drilling cuttings, sludge, and hydrocarbon-contaminated soils. One of the alternatives used to treat this drilling waste is bioremediation. Consortia are a good model to study the interactions that can occur between bacterial populations during a bioremediation process, since they involve the concerted action of different microorganisms on a substrate. The objective of this research was to design a bacterial consortium capable of degrading the hydrocarbons present in oil-based drilling cuttings (diesel). Six strains were isolated from a well drilling rubble and characterized by physiological-biochemical tests, which belong to the genera: Pimelobacter sp., Bacillus sp., Aeromicrobium sp., Arthrobacter sp., Pseudomonas sp. and Flavobacterium sp. The diesel degradation capacity was evaluated by forming a mixed culture of the strains, to which the inhibition test was performed. The growth rate of the strains was determined by exponential and incremental methods. At the end of the test, a better biodegradation capacity of the Pimelobacter sp. and Arthrobacter sp, for 64.32 and 59.23% diesel removal in 45 days and high growth rate of Pimelobacter sp. and Pseudomonas sp. in exponential phase in a period of 8 hours. The consortium was designed with the strains Pimelobacter sp., Arthrobacter sp. and Pseudomonas sp. because they demonstrated to have potential for the biodegradation of gravel contaminated with hydrocarbons.