Abstract: The organic contaminations in the waste drilling fluid from Pinghu Oilfield was investigated by GC/MS and the results showed that 23 kinds of organic pollutants including hydrocarbons, acids and esters existed in the waste drilling fluid. A bacterial 16S rRNA gene clone library was constructed to detect the community diversity in the waste drilling fluid. The phylogenetic analysis indicated that most of the clones were clustered in β, γ-Proteobacteria with the phylotypes belong to γ-Proteobacteria accounting for 78.6% of the clone library. A type of bacteria identified as Serratia marcescens was isolated from the waste drilling fluid, which had positive effect on the degradation of pollutants in the waste drilling fluid, and the removal rates of COD and TOC were more than 50%.

Key words: Waste drilling fluid, 16S rRNA gene, Hydrocarbon degrading bacteria, Bioremediation