Produção de metano de vinhaça com suplementação de torta de filtro em reatores UASB em série, mesofílicos e termofílicos: desempenho do processo e diversidade microbiana
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Data
2017-12-13
Autores
Barros, Valciney Gomes de
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Universidade Estadual Paulista (Unesp)
Resumo
A produção de biogás a partir da vinhaça de cana de açúcar tem um enorme potencial do ponto de vista econômico, energético e ambiental. No entanto, a estabilidade da produção de metano e a qualidade da vinhaça biodigerida nos reatores anaeróbios ainda necessitam de estudos, quanto as exigências de nutrientes e alcalinidade, estratégias operacionais e conhecimento da microbiota. Neste trabalho, foram avaliados dois sistemas de tratamento compostos por reatores UASB, em série, para o tratamento da vinhaça na faixa de temperatura termofílica (Reatores - TR1 e TR2) e mesofílica (Reatores - MR1 e MR2). Os reatores foram operados com cargas orgânicas volumétricas (COV) crescentes de até 45 g DQOtotal (L d-1) (TR1) e 29 g DQOtotal (L d-1) (MR1). A vinhaça afluente foi suplementada com torta de filtro e as maiores produções volumétricas de metano obtidas para o sistema termofílico e mesofílico foram de 4,0 (TR1) e 1,4 (TR2) L CH4 (L d)-1 e de 2,1 (MR1) e 1,2 (MR2) L CH4 (L d)-1, respectivamente. Os filos bacterianos mais abundantes no lodo dos reatores termofílicos (TR1 e TR2) foram o Thermotogae, Firmicutes e Bacteroidetes. Para o lodo dos reatores mesofílicos (MR1 e MR2) os filos bacterianos mais abundantes foram o Bacteroidetes e o Chloroflexi. Na PCR quantitativa observaram-se quantidades equilibradas de bactérias e arquéias, a ordem Methanobacteriales predominou no sistema termofílico e a ordem Methanosarcinales predominou no sistema mesofílico. A vinhaça resultante do sistema termofílico foi submetida a tratamentos físico-químicos e oxidativos avançados e obteve-se remoção de DQO de 81% e aumento da biodegradabilidade, de 0,10 para 0,44 (DBO:DQO), melhorando a qualidade do efluente para disposição final ou para recirculação nos reatores anaeróbios.
Biogas production from sugarcane vinasse has enormous economic, energy, and environmental management potential. However, stability of methane production and quality of biodigested vinasse in anaerobic reactors still require studies, such as nutrient and alkalinity requirements, operational strategies and knowledge of the microbiota. In this work, two treatment systems composed of UASB reactors in two-stage configuration were evaluated for the treatment of vinasse in thermophilic temperature range (Reactors TR1 and TR2) and mesophilic (Reactors MR1 and MR2). The reactors were operated with increasing of organic loading rate (OLR) of up to 45 g totalCOD (L d)-1 (TR1) and 29 g totalCOD (L d)-1 (MR1). The influent vinasse was supplemented with filter cake and the highest volumetric methane production obtained in the thermophilic and mesophilic system were 4.0 (TR1) and 1.4 (TR2) L CH4 (L d)-1 and 2.1 (MR1) and 1.2 (MR2) L CH4 (L d)-1, respectively. The most abundant bacterial phyla in the sludge of thermophilic reactors (TR1 and TR2) were Thermotogae, Firmicutes, and Bacteroidetes. In mesophilic reactors sludge (MR1 and MR2), the most abundant bacterial phyla were Bacteroidetes and Chloroflexi. Quantitative PCR showed balanced amounts of bacteria and archaea, the order Methanobacteriales dominated in thermophilic system and Methanosarcinales predominated in mesophilic system. The vinasse biodigested from thermophilic system was subjected to advanced physicochemical and oxidative treatments; COD removal of 81% and biodegradability increase from 0.10 to 0.44 (BOD: COD) were achieved, improving effluent quality for final disposal or recirculation in anaerobic reactors.
Biogas production from sugarcane vinasse has enormous economic, energy, and environmental management potential. However, stability of methane production and quality of biodigested vinasse in anaerobic reactors still require studies, such as nutrient and alkalinity requirements, operational strategies and knowledge of the microbiota. In this work, two treatment systems composed of UASB reactors in two-stage configuration were evaluated for the treatment of vinasse in thermophilic temperature range (Reactors TR1 and TR2) and mesophilic (Reactors MR1 and MR2). The reactors were operated with increasing of organic loading rate (OLR) of up to 45 g totalCOD (L d)-1 (TR1) and 29 g totalCOD (L d)-1 (MR1). The influent vinasse was supplemented with filter cake and the highest volumetric methane production obtained in the thermophilic and mesophilic system were 4.0 (TR1) and 1.4 (TR2) L CH4 (L d)-1 and 2.1 (MR1) and 1.2 (MR2) L CH4 (L d)-1, respectively. The most abundant bacterial phyla in the sludge of thermophilic reactors (TR1 and TR2) were Thermotogae, Firmicutes, and Bacteroidetes. In mesophilic reactors sludge (MR1 and MR2), the most abundant bacterial phyla were Bacteroidetes and Chloroflexi. Quantitative PCR showed balanced amounts of bacteria and archaea, the order Methanobacteriales dominated in thermophilic system and Methanosarcinales predominated in mesophilic system. The vinasse biodigested from thermophilic system was subjected to advanced physicochemical and oxidative treatments; COD removal of 81% and biodegradability increase from 0.10 to 0.44 (BOD: COD) were achieved, improving effluent quality for final disposal or recirculation in anaerobic reactors.
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Palavras-chave
Carga orgânica volumétrica, Biogás, Recirculação do efluente, Suplementação de nutrientes, Reação de Fenton, Organic loading rate, Biogas, Effluent recirculation, Nutrients supplementation, Fenton reaction