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| Author(s): |
Jaqueline Cardoso Ribeiro
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD) |
| Defense date: | 2022-07-08 |
| Examining board members: |
Marcelo Zaiat;
Bruna Soares Fernandes;
Bruna de Souza Moraes;
Rogers Ribeiro;
Gustavo Henrique Ribeiro da Silva
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| Advisor: | Marcelo Zaiat |
| Abstract | |
In this work, the production of biohydrogen (bioH2), organic acids (OA) and solvents was evaluated through dark fermentation of three agroindustrial wastes: cheese whey, sugarcane vinasse and wastewater from canned tuna cooking. In the first study, an Upflow Anaerobic Sludge Blanket (UASB) reactor and a structured fixed bed (FB) reactor without pH adjustment were used for whey processing, in mesophilic condition. This first study was divided into 3 stages. Stage 1 was conducted as a control experiment with sucrose substrate and showed an average H2 yield (HY) of respectively 1.9 ± 1.9 and 1.1 ± 0.7 mol H2 mol-1 sucroseconsumed for UASB and FB reactor. Stage 2 was performed with whey as substrate and there was no production of bioH2, however a high maximum lactic acid concentration was obtained (9.6 g L-1). Stage 3 was operated with a biomass adaptation strategy, initially feeding the reactors with sucrose and gradually replacing it with whey and it brought better bioH2 results compared to stage 2. Values above 50% of H2 concentrations in biogas were obtained for UASB reactor throughout the entire stage, however, long-term bioH2 production could not be achieved. In the next study, two UASB reactors, in mesophilic (30°C) (U30) and thermophilic (55°C) (U55) conditions were operated with vinasse without pH adjustment and the same strategy of biomass adaptation with sucrose and gradual introduction of the substrate was used. BioH2 production was viable only with sucrose and pH below 3.0, with respective average values of 1.5 ± 0.7 and 1.5 ± 1.1 mol H2 mol-1 sucroseconsumed for U30 and U55, which ceased with the replacement of sucrose by vinasse. When whey and vinasse were the only substrates, non-hydrogen-producing bacteria replaced the hydrogenogenic ones found with sucrose, as the pH value in the reactors naturally increased. Promising results for the production of OA and solvents were obtained with vinasse, with an average yield of 376 ± 52 and 248 ± 122 mg CODAO g-1 CODtin for U30 and U55 reactors, respectively. In the last study, a continuous mixing reactor fed with wastewater from cooking of canned tuna was evaluated. Extremely satisfactory results of substrate conversion to OA were obtained with a maximum acidification degree of 73%. However, it was not possible to obtain a high selectivity of products. Substrate composition proved to be as important as pH, as some amino acids (AA) may have different degradation products depending on operational conditions or interactions with other AA, making it difficult to obtain high selectivity in the process. The three substrates evaluated in this study showed great potential for OA production through dark fermentation and it is worth noting that extremely promising results were obtained even in the stages with no pH adjustment. (AU) | |
| FAPESP's process: | 17/06940-6 - Evaluation of acidogenic and methanogenic anaerobic reactors in the treatment of vinasse and whey without alkalination |
| Grantee: | Jaqueline Cardoso Ribeiro |
| Support Opportunities: | Scholarships in Brazil - Doctorate |