Up-flow anaerobic sludge blanket bioreactor for the production of carboxylates: effect of inocula on process performance and microbial communities
Abstract This research investigated the acidogenic fermentation (AF) of sugar cane molasses in an up-flow anaerobic sludge blanket (UASB) reactor for the production of carboxylates. The first step was to assess the optimum process temperature (25, 35 or 55 ºC) using two different granular inocula, o...
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SpringerOpen
2025-01-01
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| Series: | Bioresources and Bioprocessing |
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| Online Access: | https://doi.org/10.1186/s40643-025-00839-y |
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| author | Adrián Lago Silvia Greses Inés Moreno Cristina González-Fernández |
| author_facet | Adrián Lago Silvia Greses Inés Moreno Cristina González-Fernández |
| author_sort | Adrián Lago |
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| description | Abstract This research investigated the acidogenic fermentation (AF) of sugar cane molasses in an up-flow anaerobic sludge blanket (UASB) reactor for the production of carboxylates. The first step was to assess the optimum process temperature (25, 35 or 55 ºC) using two different granular inocula, one from a brewery company (BGS) and other from a paper plant company (PGS). These experiments determined that the most suitable temperature for carboxylates production was 25 ºC, obtaining higher bioconversions (27.3 ± 0.3% using PGS and 39.2 ± 0.2% using BGS), despite the low pH value recorded (4.0-4.2). Then, both inocula were tested in UASB reactors. As a consequence of the operational conditions (25 ºC, pH = 5.5-6, organic loading rate (OLR) = 3 gCOD·L-1·d-1 and hydraulic retention time (HRT) = 10 d), the microbial communities changed from those typical for biogas production to those specialised in the production of volatile fatty acids (VFAs). Indeed, the highest bioconversion efficiency (70.1%) was obtained with BGS, where uncultured Eubacteriaceae family microorganisms (56.0%) prevailed, enhancing the production of butyric acid (59.5 ± 2.4%w/w). Consequently, this inoculum was used to further identify the OLR threshold that should not be exceeded to attain optimal carboxylates production. OLR of 6 gCOD·L-1·d-1 resulted in a decrease in bioconversion efficiency (59.5%). The VFAs pool was dominated by butyric acid (63.0 ± 1.4%w/w at an OLR of 4.5 gCOD·L-1·d-1 and 52.8 ± 2.2%w/w at 6 gCOD·L-1·d-1). The microbial community became even more specialised, increasing the presence of Firmicutes and Actinobacteriota phyla, proving that the imposed conditions favoured the production of VFAs when operating semicontinuously fed UASB reactors. |
| format | Article |
| id | doaj-art-588a4e92216f4253b19d4bb8f95e40b0 |
| institution | Kabale University |
| issn | 2197-4365 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | SpringerOpen |
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| series | Bioresources and Bioprocessing |
| spelling | doaj-art-588a4e92216f4253b19d4bb8f95e40b02025-01-26T12:12:33ZengSpringerOpenBioresources and Bioprocessing2197-43652025-01-0112111510.1186/s40643-025-00839-yUp-flow anaerobic sludge blanket bioreactor for the production of carboxylates: effect of inocula on process performance and microbial communitiesAdrián Lago0Silvia Greses1Inés Moreno2Cristina González-Fernández3Biotechnology Processes Unit, IMDEA EnergyBiotechnology Processes Unit, IMDEA EnergyThermochemical Processes Unit, IMDEA EnergyBiotechnology Processes Unit, IMDEA EnergyAbstract This research investigated the acidogenic fermentation (AF) of sugar cane molasses in an up-flow anaerobic sludge blanket (UASB) reactor for the production of carboxylates. The first step was to assess the optimum process temperature (25, 35 or 55 ºC) using two different granular inocula, one from a brewery company (BGS) and other from a paper plant company (PGS). These experiments determined that the most suitable temperature for carboxylates production was 25 ºC, obtaining higher bioconversions (27.3 ± 0.3% using PGS and 39.2 ± 0.2% using BGS), despite the low pH value recorded (4.0-4.2). Then, both inocula were tested in UASB reactors. As a consequence of the operational conditions (25 ºC, pH = 5.5-6, organic loading rate (OLR) = 3 gCOD·L-1·d-1 and hydraulic retention time (HRT) = 10 d), the microbial communities changed from those typical for biogas production to those specialised in the production of volatile fatty acids (VFAs). Indeed, the highest bioconversion efficiency (70.1%) was obtained with BGS, where uncultured Eubacteriaceae family microorganisms (56.0%) prevailed, enhancing the production of butyric acid (59.5 ± 2.4%w/w). Consequently, this inoculum was used to further identify the OLR threshold that should not be exceeded to attain optimal carboxylates production. OLR of 6 gCOD·L-1·d-1 resulted in a decrease in bioconversion efficiency (59.5%). The VFAs pool was dominated by butyric acid (63.0 ± 1.4%w/w at an OLR of 4.5 gCOD·L-1·d-1 and 52.8 ± 2.2%w/w at 6 gCOD·L-1·d-1). The microbial community became even more specialised, increasing the presence of Firmicutes and Actinobacteriota phyla, proving that the imposed conditions favoured the production of VFAs when operating semicontinuously fed UASB reactors.https://doi.org/10.1186/s40643-025-00839-yAnaerobic fermentationSugar cane molassesGranular sludgeCarboxylates |
| spellingShingle | Adrián Lago Silvia Greses Inés Moreno Cristina González-Fernández Up-flow anaerobic sludge blanket bioreactor for the production of carboxylates: effect of inocula on process performance and microbial communities Bioresources and Bioprocessing Anaerobic fermentation Sugar cane molasses Granular sludge Carboxylates |
| title | Up-flow anaerobic sludge blanket bioreactor for the production of carboxylates: effect of inocula on process performance and microbial communities |
| title_full | Up-flow anaerobic sludge blanket bioreactor for the production of carboxylates: effect of inocula on process performance and microbial communities |
| title_fullStr | Up-flow anaerobic sludge blanket bioreactor for the production of carboxylates: effect of inocula on process performance and microbial communities |
| title_full_unstemmed | Up-flow anaerobic sludge blanket bioreactor for the production of carboxylates: effect of inocula on process performance and microbial communities |
| title_short | Up-flow anaerobic sludge blanket bioreactor for the production of carboxylates: effect of inocula on process performance and microbial communities |
| title_sort | up flow anaerobic sludge blanket bioreactor for the production of carboxylates effect of inocula on process performance and microbial communities |
| topic | Anaerobic fermentation Sugar cane molasses Granular sludge Carboxylates |
| url | https://doi.org/10.1186/s40643-025-00839-y |
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