High-throughput sequencing reveals microbial community dynamics in two treatment systems for oil field-produced water

Petroleum-associated water harbors diverse microbial communities, including hydrocarbon-degrading bacteria, sulfate-reducing bacteria, and methanogenic archaea. The growth and metabolism of these organisms, as well as their community composition, can affect various aspects of oil field development and oil produced water treatment. In this study, Illumina-based 16S rRNA gene sequencing was used to analyze the microbial community structures of oilfield produced water processed at two treatment stations and subjected to different treatment protocols. Significant differences in microbial community alpha-diversity and richness resulted from the different treatment protocols. The treatment of oil produced water effectively reduced the oil content, accompanied by the a reduction in Desulfobacterota. Proteobacteria was the dominant phylum in oil produced water; its core presence, along with Patescibacteria and Desulfobacterota, was identified in a co-occurrence network analysis of the microbial community. Redundancy analysis showed significant positive correlations between microbial community diversity and the oil and suspended solids contents of the oil produced water, highlighting the role of treatment protocols in shaping both microbial composition and water characteristics. Thus, this study provides potential insights into the processes of souring in oil fields and contributes to the theoretical understanding of oil-produced water treatment, which may inform future optimization of treatment protocols.