Study on the assessment of humification processes during biodegradation of heavy residual fuel oil

Jelena Avdalović; Srđan Miletić; Olga Božović; Tatjana Šolević Knudsen; Dalibor Stanković; Nikoleta Lugonja; Snežana Spasić; Kristina Joksimović; Igor Dragičević; Miroslav M Vrvić

doi:10.1016/j.scitotenv.2021.149099

Study on the assessment of humification processes during biodegradation of heavy residual fuel oil

Sci Total Environ. 2021 Nov 25:797:149099. doi: 10.1016/j.scitotenv.2021.149099. Epub 2021 Jul 17.

Affiliations

¹ University of Belgrade-Institute of Chemistry, Technology and Metallurgy, Department of Chemistry, Njegoševa 12, 11000 Belgrade, Serbia. Electronic address: javdalovic@chem.bg.ac.rs.
² University of Belgrade-Institute of Chemistry, Technology and Metallurgy, Department of Chemistry, Njegoševa 12, 11000 Belgrade, Serbia.
³ University of Zurich, Institute of Physical Chemistry, 8057 Zürich, Winterthurerstrasse 190, Switzerland.
⁴ University of Belgrade, Faculty of Chemistry, Studentski trg 12-16, 11000 Belgrade, Serbia; University of Belgrade, Vinča Institute of Nuclear Sciences, Mike Petrovića Alasa 12-14, 11351 Vinča, Belgrade, Serbia.
⁵ Public Health Institute, Jovana Cvijića 1, 15000 Šabac, Serbia.
⁶ BREM GROUP Ltd., Oslobođenja 39b, 11090 Belgrade, Serbia.

PMID: 34303984
DOI: 10.1016/j.scitotenv.2021.149099

Abstract

The aim of this study was to investigate the creation of humic substances during biodegradation of heavy residual fuel oil, because there are indications that substances similar to humic substances are generated during biodegradation of polycyclic aromatic hydrocarbons. In the study, which lasted for 110 days, biodegradation of heavy residual fuel oil was carried out in a layer of artificial soil substrate. The initial concentration of the total petroleum hydrocarbon in the prepared artificial soil substrate (biopile) was 23.1 g kg^-1 dry weight (d.w.). At the end of the process, the total petroleum hydrocarbons were reduced to 8.1 g kg^-1 d.w. in the inoculated biopile, while the content of humic acids increased during bioremediation from 3.15 g kg^-1 d.w. to 4.95 g kg^-1 d.w. The humic acids extracted from biopile during the biodegradation process were characterized by various chemical techniques (elemental analysis, spectrofluorimetric analysis, electrochemical measurements, and size exclusion chromatography). The results showed that levels of C, H and the H/C ratio decreased as the biodegradation process progressed. This indicated that humic acids aromatization process took place and this was confirmed by the spectrofluorimetric analysis. The increase of oxygen percentage and the O/C ratio in the humic acids after the biodegradation treatment indicated an increase in functional oxygen groups. Additional analyses of humic acids from the inoculated biopile showed that they were transformed during the bioremediation process. They had greater redox and buffering capacities and a larger portion of the fractions had high molecular mass. Also, the humification parameters (the C_HAs/C_FAs ratio and C_HAs/C_org ratio) increased during the biodegradation. This is one of the few studies that describes the generation of humic substances during the biodegradation of oil compounds.

Keywords: Biodegradation; Heavy residual fuel oil; Humic acids; Humification parameters; Zymogenic microorganisms.

MeSH terms

Biodegradation, Environmental
Fuel Oils*
Hydrocarbons
Petroleum*
Soil Pollutants* / analysis

Substances

Fuel Oils
Hydrocarbons
Petroleum
Soil Pollutants