Co-digestão anaeróbia de vinhaça e águas residuárias da bovinocultura leiteira em reatores UASB, em série
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Data
2022-09-29
Autores
Caraça, Michel de Santi
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A digestão anaeróbia pode ser uma alternativa atraente para o aproveitamento energético da vinhaça e das águas residuárias da bovinocultura leiteira (ARBL) e redução dos problemas ambientais. O objetivo desse trabalho foi avaliar o efeito da co-digestão anaeróbia da vinhaça de cana-de-açúcar com ARBL, em dois reatores UASB (R1 e R2), em série, na produção de biogás e efluente de qualidade. Foi utilizado a vinhaça e as ARBL, na proporção de 3/1, sendo 75% do volume de vinhaça e 25% do volume de ARBL. Também foi realizado a recirculação do efluente do R2 para adequação do pH do afluente. As melhorias nas condições nutricionais da vinhaça em virtude da co-digestão com as ARBL, aliada a recirculação do efluente proporcionaram remoções médias de DQOtotal de 77% para o sistema (R1+R2) e produção volumétrica e específica de metano de 0,451 m3 CH4 (m3 d)-1 e 0,15 m3 CH4 (kg DQOtotal removida)-1 para o R1, respectivamente. Foram observados o consumo dos ácidos voláteis totais e aumento da alcalinidade parcial nos reatores UASB. No efluente do R2 foram observadas concentrações de NTK, P-total, Ca, Mg e Fe de 70; 31; 21; 7,4 e 3,5 mg L-1, o que indica que esses elementos permaneceram no efluente e essa característica é interessante, pois o efluente poderá ser utilizado na fertirrigação da cana-de-açúcar. A partir do potencial teórico de produção de energia elétrica, verificou-se a possibilidade da produção de energia elétrica nos reatores UASB de 10,65 kwh d-1 por m3 de vinhaça, ou seja 39% da energia elétrica necessária para processar uma tonelada de cana-de-açúcar. Portanto, a co-digestão da vinhaça e das ARBL pode ser uma opção para a melhoria nas condições operacionais dos reatores anaeróbios e seu aproveitamento energético.
Anaerobic digestion can be an attractive alternative for the energy use of vinasse and dairy cattle wastewater (DCW) and reducing environmental problems. The objective of this work was to evaluate the effect of anaerobic co-digestion of sugarcane vinasse with DCW, in two UASB reactors (R1 and R2), in series, on the production of biogas and quality effluent. Vinasse and DCW were used, in the proportion of 3/1, being 75% of the vinasse volume and 25% of the DCW volume. The recirculation of the R2 effluent was also carried out to adjust the pH of the influent. The improvements in the nutritional conditions of the vinasse due to the co-digestion with the DCW, combined with the recirculation of the effluent, provided average removals of total COD of 77% for the system (R1+R2) and volumetric and specific production of methane of 0.451 m3 CH4 (m3 d)-1 and 0.15 m3 CH4 (kg CODtotal removed)-1 for R1, respectively. It was observed the consumption of total volatile acids and increase of partial alkalinity in the UASB reactors. In the R2 effluent, concentrations of TKN, total-P, Ca, Mg and Fe of 70 were observed; 31; 21; 7.4 and 3.5 mg L-1, which indicates that these elements remained in the effluent and this characteristic is interesting, since the effluent can be used in the fertigation of sugarcane. From the theoretical potential of electric energy production, it was verified the possibility of producing electric energy in the UASB reactors of 10.65 kWh d-1 per m3 of vinasse, that is, 39% of the electric energy needed to process a ton of sugar cane. Therefore, the co-digestion of vinasse and DCW can be an option for improving the operational conditions of anaerobic reactors and their energy use.
Anaerobic digestion can be an attractive alternative for the energy use of vinasse and dairy cattle wastewater (DCW) and reducing environmental problems. The objective of this work was to evaluate the effect of anaerobic co-digestion of sugarcane vinasse with DCW, in two UASB reactors (R1 and R2), in series, on the production of biogas and quality effluent. Vinasse and DCW were used, in the proportion of 3/1, being 75% of the vinasse volume and 25% of the DCW volume. The recirculation of the R2 effluent was also carried out to adjust the pH of the influent. The improvements in the nutritional conditions of the vinasse due to the co-digestion with the DCW, combined with the recirculation of the effluent, provided average removals of total COD of 77% for the system (R1+R2) and volumetric and specific production of methane of 0.451 m3 CH4 (m3 d)-1 and 0.15 m3 CH4 (kg CODtotal removed)-1 for R1, respectively. It was observed the consumption of total volatile acids and increase of partial alkalinity in the UASB reactors. In the R2 effluent, concentrations of TKN, total-P, Ca, Mg and Fe of 70 were observed; 31; 21; 7.4 and 3.5 mg L-1, which indicates that these elements remained in the effluent and this characteristic is interesting, since the effluent can be used in the fertigation of sugarcane. From the theoretical potential of electric energy production, it was verified the possibility of producing electric energy in the UASB reactors of 10.65 kWh d-1 per m3 of vinasse, that is, 39% of the electric energy needed to process a ton of sugar cane. Therefore, the co-digestion of vinasse and DCW can be an option for improving the operational conditions of anaerobic reactors and their energy use.
Descrição
Palavras-chave
Bioenergia, Biogás, Reatores anaeróbios, Metano, Vinhoto