RESUMO
To provide new insight into the dark fermentation process, a multi-lateral study was performed to study the microbiology of 20 different lab-scale bioreactors operated in four different countries (Brazil, Chile, Mexico, and Uruguay). Samples (29) were collected from bioreactors with different configurations, operation conditions, and performances. The microbial communities were analyzed using 16S rRNA genes 454 pyrosequencing. The results showed notably uneven communities with a high predominance of a particular genus. The phylum Firmicutes predominated in most of the samples, but the phyla Thermotogae or Proteobacteria dominated in a few samples. Genera from three physiological groups were detected: high-yield hydrogen producers (Clostridium, Kosmotoga, Enterobacter), fermenters with low-hydrogen yield (mostly from Veillonelaceae), and competitors (Lactobacillus). Inocula, reactor configurations, and substrates influence the microbial communities. This is the first joint effort that evaluates hydrogen-producing reactors and operational conditions from different countries and contributes to understand the dark fermentation process.
Assuntos
Reatores Biológicos/normas , Fermentação , Hidrogênio/metabolismo , Consórcios Microbianos/genética , RNA Ribossômico 16S/genética , Anaerobiose , Clostridium/classificação , Clostridium/genética , Clostridium/metabolismo , Enterobacter/classificação , Enterobacter/genética , Enterobacter/metabolismo , Firmicutes/classificação , Firmicutes/genética , Firmicutes/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Lactobacillus/classificação , Lactobacillus/genética , Lactobacillus/metabolismo , América Latina , Proteobactérias/classificação , Proteobactérias/genética , Proteobactérias/metabolismo , Thermotoga maritima/classificação , Thermotoga maritima/genética , Thermotoga maritima/metabolismo , Veillonellaceae/classificação , Veillonellaceae/genética , Veillonellaceae/metabolismoRESUMO
O objetivo do estudo foi avaliar a degradação do hormônio 17β-estradiol com doses de cloro e tempos de contato comumente utilizados em estações de tratamento de água. A aplicação de cloro levou a pequenas alterações na maioria das variáveis analisadas. A concentração inicial de 17β-estradiol influenciou a remoção pelo cloro, e observou-se que o aumento da dose de cloro aumentou a remoção do 17β-estradiol até a dose de 2 mg.L-1. A maior remoção de hormônio obtida foi de 99%, e a inativação dos microrganismos indicadores, E. coli e coliformes totais foi de até 5,6 log para valores de CT maiores que 14 mg.min.L-1 .
The purpose of this study was to evaluate the degradation of the estrogen 17β-estradiol at doses of chlorine and contact times commonly used in water treatment plants. The application of chlorine led to minor changes in most parameters examined. The initial concentration of the hormone affected the removal by chlorine and was observed that increasing the dose of chlorine increased the removal of 17β-estradiol until the dose of 2 mg.L-1. The highest removal of hormone obtained was 99%, and inactivation of the indicator microorganisms, E. coli and total coliform was up to 5.6 log for values of CT greater than 14 mg.min.L-1 .