Processo integrado de eletrocoagulação e cultivo mixotrófico de Desmodesmus subspicatus em vinhaça de cana-de-açúcar
| Ano de defesa: | 2019 |
|---|---|
| Autor(a) principal: | |
| Orientador(a): |
Bastos, Reinaldo Gaspar
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| Banca de defesa: | |
| Tipo de documento: | Dissertação |
| Tipo de acesso: | Acesso aberto |
| Idioma: | por |
| Instituição de defesa: |
Universidade Federal de São Carlos
Câmpus Araras |
| Programa de Pós-Graduação: |
Programa de Pós-Graduação em Produção Vegetal e Bioprocessos Associados - PPGPVBA-Ar
|
| Departamento: |
Não Informado pela instituição
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| País: |
Não Informado pela instituição
|
| Palavras-chave em Português: | |
| Palavras-chave em Inglês: | |
| Palavras-chave em Espanhol: | |
| Área do conhecimento CNPq: | |
| Link de acesso: | https://repositorio.ufscar.br/handle/20.500.14289/11727 |
Resumo: | Brazil is the largest sugarcane ethanol biofuel producer of the world. The productive process generates a considerable quantity of vinasse, its main wastewater. Therefore, the vinasse disposal is one of the major challenges involved in the ethanol production. Although fertirrigation is permitted by environmental legislation, such volume is limited and the remaining vinasse needs to be treated for its disposal into the environment. Microalgae cultivation has been considered a promising vinasse treatment, because its biomass could be an interesting source of valuable bioproducts. However, due to the physicochemical characteristics of vinasse (high turbidity and acid pH), it would be advantageous to perform a pretreatment process in order to adequate the effluent as a culture medium and to allow better light incidence in it. By this way, the objective of the research was to evaluate the integrated process of electrocoagulation with subsequent Desmodesmus subspicatus microalgae mixotrophic culture in sugarcane vinasse. For this purpose, several electrocoagulation experiments were carried out with raw vinasse in a laboratory electrolytic reactor, evaluating the influence of the electrode material (aluminum or iron), spacing between plates (1-3 cm), current density (2.2-20.0 mA cm-2), agitation (0-680 rpm) and sludge separation method (sedimentation or filtration). The electrocoagulation results indicated high turbidity removal and pH adequation, from initially acid vinasse (vinasse pH ≈ 4) to values up to standard BG11 medium (BG11 pH ≈ 7.4) in all experimental conditions, which allowed direct culture of D. subspicatus without any additional treatment. At optimized conditions (aluminum electrodes spaced 1 cm, 6.1 mA cm-2 and 430 rpm) and using filtration for sludge separation, it was obtained 99.8, 40.3 and 55.5 turbidity, total organic carbon and total nitrogen removal. It was dosed dosage of 1.6 g L-1 of Al+3 by the electrolysis, which represented an electric consumption of 8.0 kWh m-3 and a process cost of R$ 14.10 m-3. The cultivation of D. subspicatus in the pre-treated vinasse showed better results using aluminum electrodes in relation to iron. The vinasse clarification achieved by the electrocoagulation process potentiated the microalga growth, achieving a higher productivity in mixotrophic cultivation (10.0 x106 cell mL-1 day-1) than heterotrophic cultivation (3.5 x106 cell mL-1 day-1). The total organic carbon and total nitrogen removal reached by the integrated process was 69.6 and 80.9%, respectively. The biomass characterization showed a lipid and protein content of 8.6 and 25.3%, respectively. It was obtained high lipid and protein productivities (75.3 and 208.2 mg L-1 day-1, respectively). Therefore, it was concluded that the integrated electrocoagulation process with subsequent D. subspicatus mixotrophic cultivation in sugarcane vinasse was technically feasible and would allow microalgae biomass, lipids and proteins production, and simultaneously, vinasse treatment. |