Avaliação do desempenho do coagulante natural tanfloc e do sulfato de alumínio para recuperação de biomassa de microalga cultivada em efluente doméstico tratado
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Data
2021-08-06
Autores
Teixeira, Mariana Souza
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Universidade Estadual Paulista (Unesp)
Resumo
Coagulantes a base de tanino, tal como o Tanfloc, apresentam potencial para separar biomassa de microalgas cultivas em estações de tratamento de esgoto. O uso do coagulante auxilia em atingir o conceito de economia circular através do reaproveitamento dos nutrientes para produção de uma biomassa e sobrenadante com baixa toxicidade. Neste contexto o objetivo deste trabalho foi avaliar o desempenho do Tanfloc SG como coagulante para separação de microalgas nativas cultivadas em esgoto doméstico digerido, comparando o seu desempenho com o sulfato de alumínio. Análises clássicas de eficiência de remoção foram utilizadas em conjunto com análise do tamanho das partículas e com índice de floculação para avaliar o desempenho do coagulante, a influência do valor do pH, o tamanho dos flocos, a resistência e capacidade de recuperação comparados ao sulfato de alumínio. Os estudos indicaram que o Tanfloc atingiu eficiências de remoção de cor, turbidez e densidade ótica maiores que 90% com apenas 5 minutos de sedimentação. A dosagem ótima para separação foi 100 mg.L-1 para o Tanfloc e 75 mg.L-1 para o sulfato de alumínio. O Tanfloc foi capaz de separar a biomassa sem alterar o pH do meio, também foi capaz de apresentar remoção satisfatórias de todos os parâmetros analisados em valores de pH 5,0, 7,0 e 8,5 e além do mais, produziu flocos mais fortes capazes de resistir a variações bruscas no gradiente de velocidade. Ambos coagulantes produziram uma biomassa rica em macronutrientes, apresentando uma relação C:N:P de 240:32,5:1 para o Tanfloc e de 154:20:1 para o sulfato de alumínio, podendo ser utilizada como biofertilizante e sobrenadante com baixa DQO, Turbidez, SST e E. coli que pode ser reutilizado para irrigação.
Tannin-based coagulants, such as Tanfloc, have the potential to be used to harvest microalgae cultivated at wastewater treatment plants. Their use would address the circular economy associated with the production of low-toxicity biomass and supernatant. Studies in this field are still scarce, and substantial gaps exist in the definitions of the flocculation process parameters. In this context, the objective of this work was to evaluate TBC performance as a natural coagulant for harvesting microalgae biomass grown in sanitary effluent digested in an up flow biofilter, as well establishing a path to enable recovery and reuse of wastewater nutrients. Classical removal techniques combined with image analysis and light scattering-based equipment were used to evaluate the coagulant performance, floc strength, and floc recovery compared to aluminum sulfate (AS). The results showed that TBC was able to efficiently harvest algal biomass from the effluent, achieving color, turbidity, and optical density (OD) removal efficiencies greater than 90% with only 5 minutes of sedimentation. The optimal harvesting dosage was 100 mg.L-1 for TBC and 75 mg.L-1 for AS. TBC presented the advantage of harvesting biomass without changing the pH of the medium and was also able to present satisfactory removal of the analyzed parameters (color, turbidity and OD) at pH values of 5.0, 7.0, and 8.5. In addition, TBC produced stronger flocs than AS, showing a better ability to resist breakage upon sudden shear rate variations. Tanfloc and aluminum sulfate produced a macronutrient-rich biomass with a C:N:P ratio of 240:32,5:1 and 154:20:1 respectively, and a supernatant with low COD, Turbidity, TSS, e E. Coli. that can be used for unrestricted irrigation.
Tannin-based coagulants, such as Tanfloc, have the potential to be used to harvest microalgae cultivated at wastewater treatment plants. Their use would address the circular economy associated with the production of low-toxicity biomass and supernatant. Studies in this field are still scarce, and substantial gaps exist in the definitions of the flocculation process parameters. In this context, the objective of this work was to evaluate TBC performance as a natural coagulant for harvesting microalgae biomass grown in sanitary effluent digested in an up flow biofilter, as well establishing a path to enable recovery and reuse of wastewater nutrients. Classical removal techniques combined with image analysis and light scattering-based equipment were used to evaluate the coagulant performance, floc strength, and floc recovery compared to aluminum sulfate (AS). The results showed that TBC was able to efficiently harvest algal biomass from the effluent, achieving color, turbidity, and optical density (OD) removal efficiencies greater than 90% with only 5 minutes of sedimentation. The optimal harvesting dosage was 100 mg.L-1 for TBC and 75 mg.L-1 for AS. TBC presented the advantage of harvesting biomass without changing the pH of the medium and was also able to present satisfactory removal of the analyzed parameters (color, turbidity and OD) at pH values of 5.0, 7.0, and 8.5. In addition, TBC produced stronger flocs than AS, showing a better ability to resist breakage upon sudden shear rate variations. Tanfloc and aluminum sulfate produced a macronutrient-rich biomass with a C:N:P ratio of 240:32,5:1 and 154:20:1 respectively, and a supernatant with low COD, Turbidity, TSS, e E. Coli. that can be used for unrestricted irrigation.
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Palavras-chave
Engenharia ambiental, Separação de microalgas, Tanfloc, Resistência do floco, Biofertilizante, Environmental engineering, Microalgae harvestin, Tanfloc, Strength factor, Biofertilizer