Sulfate-based coagulants can suppress methanogenesis in treated oil sands fine tailings
Abstract Bitumen extraction from mined oil sands ore generates a large volume of fluid fines tailings (FFT) that must be incorporated into either aquatic or terrestrial reclamation landforms. Mine operators are developing various tailings technologies to accelerate FFT dewatering, including the addi...
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BMC
2025-08-01
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| Series: | Geochemical Transactions |
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| Online Access: | https://doi.org/10.1186/s12932-025-00104-3 |
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| author | Philip A. Adene Mojtaba Abdolahnezhad Mian N. Anwar Ania C. Ulrich Matthew B. J. Lindsay |
| author_facet | Philip A. Adene Mojtaba Abdolahnezhad Mian N. Anwar Ania C. Ulrich Matthew B. J. Lindsay |
| author_sort | Philip A. Adene |
| collection | DOAJ |
| description | Abstract Bitumen extraction from mined oil sands ore generates a large volume of fluid fines tailings (FFT) that must be incorporated into either aquatic or terrestrial reclamation landforms. Mine operators are developing various tailings technologies to accelerate FFT dewatering, including the addition of chemical coagulants and flocculants. However, the impacts of these coagulants and flocculants on biogeochemical processes in treated FFT are not fully understood. We conducted anaerobic batch experiments to examine the influence of different doses (i.e., 0, 500, 1000, and 1500 ppm) of sulfate-based coagulants, including aluminum sulfate (alum) [Al2(SO4)3∙nH2O], ferric sulfate (ferric) [Fe2(SO4)3∙nH2O], and calcium sulfate (gypsum) [CaSO4∙2H2O], on biogenic gas production and microbial communities in treated FFT. Our results show that sulfate addition stimulated microbial sulfate reduction, which inhibited methanogenesis in coagulated FFT relative to experimental controls. Sulfate depletion preceded increased methane production in the 500 ppm gypsum experiment, while larger ferric and alum doses produced higher sulfate concentrations and larger pH decreases. 16 S rRNA sequencing revealed that Comamonadaceae, Anaerolineaceae, and Desulfocapsaceae were the major bacterial families, while Methanoregulaceae and Methanosaetaceae dominated the archaeal families in all treatments. Precipitation of iron(II) sulfides limited dissolved hydrogen sulfide concentrations in experiments where Fe availability was not limited. Our results indicate that addition of sulfate-based coagulants can stimulate microbial sulfate reduction and suppress methanogenesis. However, resumption of methane production following sulfate depletion reveals complex interactions among biogeochemical reaction pathways. Overall, this study demonstrates that biogeochemical cycling of carbon, sulfur, and iron are important considerations for the development and implementation of tailings treatment technologies. |
| format | Article |
| id | doaj-art-58b866db3e2a4e2592e26dc80261e1f6 |
| institution | Kabale University |
| issn | 1467-4866 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | BMC |
| record_format | Article |
| series | Geochemical Transactions |
| spelling | doaj-art-58b866db3e2a4e2592e26dc80261e1f62025-08-24T11:52:16ZengBMCGeochemical Transactions1467-48662025-08-0126112110.1186/s12932-025-00104-3Sulfate-based coagulants can suppress methanogenesis in treated oil sands fine tailingsPhilip A. Adene0Mojtaba Abdolahnezhad1Mian N. Anwar2Ania C. Ulrich3Matthew B. J. Lindsay4Department of Geological Sciences, University of SaskatchewanDepartment of Geological Sciences, University of SaskatchewanDepartment of Civil & Environmental Engineering, University of AlbertaDepartment of Civil & Environmental Engineering, University of AlbertaDepartment of Geological Sciences, University of SaskatchewanAbstract Bitumen extraction from mined oil sands ore generates a large volume of fluid fines tailings (FFT) that must be incorporated into either aquatic or terrestrial reclamation landforms. Mine operators are developing various tailings technologies to accelerate FFT dewatering, including the addition of chemical coagulants and flocculants. However, the impacts of these coagulants and flocculants on biogeochemical processes in treated FFT are not fully understood. We conducted anaerobic batch experiments to examine the influence of different doses (i.e., 0, 500, 1000, and 1500 ppm) of sulfate-based coagulants, including aluminum sulfate (alum) [Al2(SO4)3∙nH2O], ferric sulfate (ferric) [Fe2(SO4)3∙nH2O], and calcium sulfate (gypsum) [CaSO4∙2H2O], on biogenic gas production and microbial communities in treated FFT. Our results show that sulfate addition stimulated microbial sulfate reduction, which inhibited methanogenesis in coagulated FFT relative to experimental controls. Sulfate depletion preceded increased methane production in the 500 ppm gypsum experiment, while larger ferric and alum doses produced higher sulfate concentrations and larger pH decreases. 16 S rRNA sequencing revealed that Comamonadaceae, Anaerolineaceae, and Desulfocapsaceae were the major bacterial families, while Methanoregulaceae and Methanosaetaceae dominated the archaeal families in all treatments. Precipitation of iron(II) sulfides limited dissolved hydrogen sulfide concentrations in experiments where Fe availability was not limited. Our results indicate that addition of sulfate-based coagulants can stimulate microbial sulfate reduction and suppress methanogenesis. However, resumption of methane production following sulfate depletion reveals complex interactions among biogeochemical reaction pathways. Overall, this study demonstrates that biogeochemical cycling of carbon, sulfur, and iron are important considerations for the development and implementation of tailings treatment technologies.https://doi.org/10.1186/s12932-025-00104-3Oil sandsTreated tailingsBiogeochemistryMethanogenesisSulfate reduction |
| spellingShingle | Philip A. Adene Mojtaba Abdolahnezhad Mian N. Anwar Ania C. Ulrich Matthew B. J. Lindsay Sulfate-based coagulants can suppress methanogenesis in treated oil sands fine tailings Geochemical Transactions Oil sands Treated tailings Biogeochemistry Methanogenesis Sulfate reduction |
| title | Sulfate-based coagulants can suppress methanogenesis in treated oil sands fine tailings |
| title_full | Sulfate-based coagulants can suppress methanogenesis in treated oil sands fine tailings |
| title_fullStr | Sulfate-based coagulants can suppress methanogenesis in treated oil sands fine tailings |
| title_full_unstemmed | Sulfate-based coagulants can suppress methanogenesis in treated oil sands fine tailings |
| title_short | Sulfate-based coagulants can suppress methanogenesis in treated oil sands fine tailings |
| title_sort | sulfate based coagulants can suppress methanogenesis in treated oil sands fine tailings |
| topic | Oil sands Treated tailings Biogeochemistry Methanogenesis Sulfate reduction |
| url | https://doi.org/10.1186/s12932-025-00104-3 |
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