Obtenção de consórcio de bactérias fotoheterotróficas geradoras de H2 visando sua produção em reator anaeróbio em batelada
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Data
2016-04-04
Autores
Ríos Alcaraz, Francisco Abraham [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A bioconversão de diferentes materiais orgânicos em hidrogênio é uma tecnologia sustentável. Inóculos de climas tropicais, como o Brasil, com temperaturas médias de 25°C podem favorecer o crescimento bacteriano. A geração de hidrogênio com consórcios bacterianos têm vantagens sobre culturas puras quanto aplicado no tratamento de águas residuárias. O hidrogênio pode ser gerado em duas fases durante os processos anaeróbios. Em primeiro lugar, hidrogênio e ácidos orgânicos podem ser produzidos por processos fermentativos. Esses ácidos gerados podem ser usados por bactérias fotoheterotróficas na segunda fase, durante a operação dos reatores anaeróbios na presença de luz. O objetivo deste estudo foi avaliar o potencial de produção hidrogênio a partir de resíduos orgânicos por consórcios de bactérias fotoheterotróficas. Foram feitos 12 ensaios (I-XII) separadamente, em triplicatas de reatores anaeróbios em batelada, em meio de cultivo Rhodospirillaceae, headspace N2 (100%), pH 7.0+1, a 37ºC. Foram comprovados os efeitos com duas potências de intensidade de luz (8,8±1 e 18,5±1 W/m2) e diferentes concentrações de ácidos butírico, acético, além de efluentes de processos fermentativos procedentes de glicerol bruto e águas residuárias citrícolas. As condições ótimas para a produção de hidrogênio foram de 18.5±1 W/m2 de intensidade de luz e 1.7 g/L para o ácido acético (II), 1.0 g/L para o ácido butírico (V), 1.0 g de COD/L de glicerol efluente (IX), e 0.5 g de DQO/L para o efluente de águas residuárias citrícolas (XII). Nessas condições, a produção de hidrogênio foi de 4.9 (II), 4.0 (V), 3.0 (IX) e 2.3 (XII) mmol H2/L, eficiência de remoção de 92.5, 83.6, 76.1, 83.1%, e crescimento celular (ABS660) de 3.0(II), 1.6 (V), 1.6 (IX), 1.8 (XII) às 61, 54, 64 e 65 h, respectivamente. A análise microscópica da biomassa mostrou predominância de bacilos Gram negativos, morfologia característica de bactérias fotoheterotróficas geradoras de H2. O pH observado de 10.1 (II), 9.8 (V), 9.9 (IX) e 9.7 (XII), justificou os consumos de ácidos orgânicos pelo consórcio fotoheterotrófico no final da operação. Os consórcios bacterianos fotoheterotróficos apresentaram potencial na produção de biohidrogênio elevado, o que pode ser aplicado no tratamento de resíduos orgânicos que contenham ácidos voláteis.
The bioconversion of different organic materials to hydrogen is a sustainable technology. Inocula from tropical climates such as Brazil which average temperatures around 25°C may favour the bacterial growth. Hydrogen generation with bacterial consortia have advantages over pure cultures regarding application to wastewater treatment. The hydrogen can be generates in two stages during the anaerobic processes. Firstly, hydrogen and organic acids can be produced by dark fermentation. The acids generated during the first stage of the fermentation process can be used by phototrophic bacteria in the second stage during the operation of anaerobic batch reactors on the light presence. The aim of this study was evaluate the hydrogen producing potential from organic wastes by phototrophic bacterial consortia. Assays (I - XII) were made separately in triplicates of anaerobic batch reactors, Rhodospirillaceae medium (Chi Mei Lee, 2005), headspace with N2 (100%), pH 7.0+1, at 37oC. Effects with two potencies of light intensity (8.8±1 and 18.5±1 W/m2 ) and different concentrations of butyric acid, acetic acid and dark fermentation effluents from crude glycerol and citrus wastewaters were optimized. The optimal conditions for hydrogen production from phototrophic consortia were 18.5±1 W/m2 of light intensity and 1.7 g/L for acetic acid (II), 1.0 g/L for butyric acid (V), 1.0 g COD/L for Glycerol effluent (IX), and 0.5 g COD/L for citrus wastewater effluent (XII). Under the optimum conditions, the hydrogen production of 4.9 (II), 4.0 (V), 3.0 (IX) and 2.3 (XII) mmol H2 L -1 with a removal efficiency of 92.5, 83.6, 76.1, 83.1% respectively, was obtained. High cellular growth (ABS660) of 3.0 (II), 1.6 (V), 1.6 (IX), 1.8 (XII) at 61, 54, 64 and 65 hours, respectively was observed. Microscopic analysis of biomass showed the predominance of Gram negative rods; which morphology is characteristic of phototrophic H2-generating bacteria. The pH observed for essays 10.1 (II), 9.8 (V), 9.9 (IX) and 9.7 (XII) respectively could justify the consumptions of organic acids by the phototrophic consortia at the end of operation. The phototrophic bacterial consortia showed high potential on hydrogen bio-production and they can be applied on organic wastes containing volatile acids.
The bioconversion of different organic materials to hydrogen is a sustainable technology. Inocula from tropical climates such as Brazil which average temperatures around 25°C may favour the bacterial growth. Hydrogen generation with bacterial consortia have advantages over pure cultures regarding application to wastewater treatment. The hydrogen can be generates in two stages during the anaerobic processes. Firstly, hydrogen and organic acids can be produced by dark fermentation. The acids generated during the first stage of the fermentation process can be used by phototrophic bacteria in the second stage during the operation of anaerobic batch reactors on the light presence. The aim of this study was evaluate the hydrogen producing potential from organic wastes by phototrophic bacterial consortia. Assays (I - XII) were made separately in triplicates of anaerobic batch reactors, Rhodospirillaceae medium (Chi Mei Lee, 2005), headspace with N2 (100%), pH 7.0+1, at 37oC. Effects with two potencies of light intensity (8.8±1 and 18.5±1 W/m2 ) and different concentrations of butyric acid, acetic acid and dark fermentation effluents from crude glycerol and citrus wastewaters were optimized. The optimal conditions for hydrogen production from phototrophic consortia were 18.5±1 W/m2 of light intensity and 1.7 g/L for acetic acid (II), 1.0 g/L for butyric acid (V), 1.0 g COD/L for Glycerol effluent (IX), and 0.5 g COD/L for citrus wastewater effluent (XII). Under the optimum conditions, the hydrogen production of 4.9 (II), 4.0 (V), 3.0 (IX) and 2.3 (XII) mmol H2 L -1 with a removal efficiency of 92.5, 83.6, 76.1, 83.1% respectively, was obtained. High cellular growth (ABS660) of 3.0 (II), 1.6 (V), 1.6 (IX), 1.8 (XII) at 61, 54, 64 and 65 hours, respectively was observed. Microscopic analysis of biomass showed the predominance of Gram negative rods; which morphology is characteristic of phototrophic H2-generating bacteria. The pH observed for essays 10.1 (II), 9.8 (V), 9.9 (IX) and 9.7 (XII) respectively could justify the consumptions of organic acids by the phototrophic consortia at the end of operation. The phototrophic bacterial consortia showed high potential on hydrogen bio-production and they can be applied on organic wastes containing volatile acids.
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Palavras-chave
Hidrogênio, Ácido acético, Ácido butírico, Efluentes de fermentação, Glicerol bruto, Resíduos citrícolas, Bactérias fotoheterotróficas, Hydrogen, Butyric acid, Acetic acid, Crude glycerol, Photoheterotrophic bacterial consortia, Hydrogen bio-production