Digestão anaeróbia da vinhaça em reatores horizontais de alta taxa: desempenho do processo e composição da microbiota
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Data
2022-01-27
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Universidade Estadual Paulista (Unesp)
Resumo
A recuperação de recursos tem sido extremamente abordada nos tempos atuais, trazendo uma nova consciência coletiva dos aspectos ambientais, sociais e governamentais (ESG). A produção de biogás a partir da vinhaça de cana-de-açúcar possui um grande potencial para as questões supracitadas para o setor sucroenergético. O emprego de reatores anaeróbios horizontais de leito fixo (RAHLF) para a digestão anaeróbia e produção de biogás a partir de resíduos apresenta grandes vantagens em virtude a sua robustez, facilidade construtiva, operacional e econômica. No entanto, esta conformação de sistema para a biodigestão da vinhaça ainda foi pouco estudada. Neste estudo foi avaliado o efeito do aumento progressivo da carga orgânica volumétrica (COV) sobre o desempenho do sistema RAHLF e sobre a microbiota presente no lodo, durante três períodos de safra da cana consecutivos (810 dias). O experimento foi dividido em fase de partida e fases de 1 a 9, sendo a última fase distinguida pela combinação da digestão anaeróbia com o processo Fenton. Foram aplicadas COV de até 27,9 g de DQO L.d-¹ nos RAHLF apresentando estabilidade durante todo período experimental, e remoções de DQO total acima de 60%, sendo as melhores remoções atingidas na fase 9 (85%), sem suplementação nutricional. Na fase 9 promoveram-se a redução de sulfato, sulfeto e fenóis no afluente, o que favoreceu a produção volumétrica de metano (0,28 L CH4 (L d)-1) em relação à fase anterior para condições de COVs similares. No entanto as médias de produção específica de metano, para ambas as fases, apresentaram-se semelhantes. O sequenciamento de nova geração (Illumina) realizado no lodo dos reatores em diferentes fases do experimento demonstrou uma comunidade microbiana diversa, com elevada abundância de bactérias dos filos Firmicutes, Proteobacteria, Cloacimonetes e Bacteroidetes, que contribuíram para a eficácia do sistema. A qPCR realizada apresentou alterações na composição microbiana, indicando que houve tendência dos microrganismos a realizarem a metanização pelas vias hidrogenotróficas.
The recovery of resources has been extremely addressed nowadays, bringing a new collective awareness of environmental, social and governmental aspects (ESG). The production of biogas from sugarcane vinasse has great potential for the aforementioned issues for the sugar-energy sector. The use of HARFB reactors for anaerobic digestion and biogas production from residues has great advantages due to its robustness, ease of construction, operation and economics, however, this conformation of a system for biodigestion of vinasse has been little studied. In this sense, this study evaluated the effects of the progressive increase in OLR on the performance of the HARFB system and on the microbiota present in the sludge, during three consecutive sugarcane harvest periods (810 days). The experiment was divided into a starting phase and phases from 1 to 9, the last phase being distinguished by the combination of anaerobic digestion with the Fenton process. The system reached OLR of up to 27.9 g of COD Ld- ¹, showing stability throughout the experimental period, and total COD removals above 60%, with the best removals achieved in phase 9 (85%), without nutritional supplementation during the entire experiment. Phase 9 promoted the reduction of sulfate, sulfide and phenols in the influent and favored the volumetric methane production (0.28 L CH4 (L d)-1 ) compared to the previous phase for similar OLR conditions. However, the specific methane production averages for both phases were similar. The next generation sequencing (Illumina) carried out in the reactor sludge at different stages of the experiment showed a diverse microbial community, with a high abundance of bacteria from the phyla Firmicutes, Proteobacteria, Cloacimonetes and Bacteroidetes, which contributed to the efficiency of the system. The qPCR performed showed changes in the microbial composition, indicating that there was a tendency for microorganisms to carry out methanization by hydrogenotrophic pathways.
The recovery of resources has been extremely addressed nowadays, bringing a new collective awareness of environmental, social and governmental aspects (ESG). The production of biogas from sugarcane vinasse has great potential for the aforementioned issues for the sugar-energy sector. The use of HARFB reactors for anaerobic digestion and biogas production from residues has great advantages due to its robustness, ease of construction, operation and economics, however, this conformation of a system for biodigestion of vinasse has been little studied. In this sense, this study evaluated the effects of the progressive increase in OLR on the performance of the HARFB system and on the microbiota present in the sludge, during three consecutive sugarcane harvest periods (810 days). The experiment was divided into a starting phase and phases from 1 to 9, the last phase being distinguished by the combination of anaerobic digestion with the Fenton process. The system reached OLR of up to 27.9 g of COD Ld- ¹, showing stability throughout the experimental period, and total COD removals above 60%, with the best removals achieved in phase 9 (85%), without nutritional supplementation during the entire experiment. Phase 9 promoted the reduction of sulfate, sulfide and phenols in the influent and favored the volumetric methane production (0.28 L CH4 (L d)-1 ) compared to the previous phase for similar OLR conditions. However, the specific methane production averages for both phases were similar. The next generation sequencing (Illumina) carried out in the reactor sludge at different stages of the experiment showed a diverse microbial community, with a high abundance of bacteria from the phyla Firmicutes, Proteobacteria, Cloacimonetes and Bacteroidetes, which contributed to the efficiency of the system. The qPCR performed showed changes in the microbial composition, indicating that there was a tendency for microorganisms to carry out methanization by hydrogenotrophic pathways.
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Palavras-chave
Biogás, Fenton, Recirculação de efluente, Sistema RAHLF, Tratamento de efluentes, Vinhaça, Fenóis