Hydrocarbons removal from real marine sediments: Analysis of degradation pathways and microbial community development during bioslurry treatment

In this study, real marine sediments polluted by petroleum compounds were treated by means of a bioslurry pilot scale reactor. The treatment performance was evaluated by measuring the removal of total petroleum hydrocarbon (TPH), coupled to further analyses required to understand the mechanisms involved in the biodegradation process. The maximum TPH-removal efficiency reached 86 % at the end of experiments. Moreover, high throughput 16S RNA gene sequencing was used to describe the microbiome composition in sediment prior to, and after, bioslurry treatment, in order to identify the taxa mostly entailed in the TPH removal process. The raw sediment was mostly colonized by members of Sulfurimonas genus; after bioslurry treatment, it was noticed a shift in the microbial community composition, with Proteobacteria phylum dominating the remediation environment (high increase in terms of growth for Hydrogenophaga and Sphingorhabdus genera) along with the Phaeodactylibacter genus (Bacteroidetes). Furthermore, the assessment of gaseous emissions from the system allowed to quantify the volatile hydrocarbon component and, consequently, to obtain a more accurate evaluation of TPH-removal pathway by the bioslurry system. Finally, phytotoxicity tests on sediment samples highlighted an increase of the treated sample quality status compared to the untreated one.

Automated summary

In this study, marine sediments polluted by petroleum compounds were treated using a bioslurry pilot scale reactor. The efficiency of TPH removal was evaluated and the mechanisms involved in the biodegradation process were analyzed. The maximum TPH-removal efficiency reached 86%. The microbiome composition in the sediment was analyzed using 16S RNA gene sequencing, which revealed a shift in the microbial community composition after bioslurry treatment. Gaseous emissions from the system were also assessed to obtain a more accurate evaluation of TPH-removal pathway. Phytotoxicity tests showed an improvement in the treated sample quality compared to the untreated sample.