DesinFix TM 135 in fermentation process for bioethanol production

Abstract

Brazil has the world’s largest ethanol production from sugarcane, but bacterial contamination decreases the ethanol yields. It was shown that the biocide DesinFix™ 135 can reduce the contamination without decreasing the yeasts’ viability or negatively affecting the ethanol production.

Bioenergy from stillage anaerobic digestion to enhance the energy balance ratio of ethanol production

“…Lactobacillus fermentum and Leuconostoc mesenteroides in samples from distilleries with serious bacterial contamination problems (Oliva-Neto and Yokoya, 1998;Oliva-Neto et al, 2014). In other study, the application of a biodegradable biocide to contaminated samples has also reduced the viable cells of different Lactobacillus and Leuconostoc species (Barth et al, 2014). Other available biocides include methyldithiocarbamate, quaternary ammonium and formaldehyde (Oliva-Neto et al, 2013).…”

“…Regarding specifically sulfate, its presence on stillages from ethanol fuel are related with the addition of sulfuric acid during the fermentation step, in order to prevent the contamination by nonethanol-producing microorganisms, such as bacteria and wild yeasts, and the flocculation of the cells (BNDES and CGEE, 2008;Oliva-Neto et al, 2013;Barth et al, 2014). The even higher concentrations of sulfate in stillages from molasses are also associated with the previous use of sulfuric acid in the step of sugar clarification (BNDES and CGEE, 2008).…”

“…Besides, current studies investigate alternative approaches to minimize or even eliminate the use of sulfuric acid in fermentative processes, since this practice may also affect negatively the yeast activity. The recurrent exposure of yeasts to low pH conditions (~2.0e3.0) tends to affect the activity of the cells by impairing enzymatic functions, directly reducing the ethanol yield due to decreases in the cell viability (Oliva-Neto et al, 2013;Barth et al, 2014). In this context, the use of biocides to control the microbial contamination in fermenters is considered an attractive alternative since it is possible achieving the microbial control without inhibiting the yeast activity.…”

Biodigestão anaeróbia termofílica de vinhaça em sistemas combinados do tipo acidogênico-metanogênico para potencialização da recuperação de bioenergia em biorrefinarias de cana-de-açúcar de primeira geração

“…Adicionalmente ao emprego de antibióticos como método de controle da competição microbiana por substrato, o emprego de ácido sulfúrico nas dornas de fermentação é característica comum do processo Melle-Bointot 66 , buscando simultaneamente a inibição bacteriana e a prevenção da floculação das leveduras (Barth et al, 2014 (Vásquez e Nakasaki, 2016).…”

“…Neste caso, a corrente de leveduras recuperadas (creme de levedura) é inicialmente diluída em água, sofrendo em seguida a adição de ácido sulfúrico até que o pH do meio seja reduzido a pelo menos 2,5. Tal procedimento previne simultaneamente a contaminação bacteriana do meio e a floculação do fermento (Oliva-Neto et al, 2013;Barth et al, 2014) (Griffin et al, 1998, Chachkhiani et al, 2004, Hori et al, 2006 (Wasserfallen et al, 2000, Nakamura et al, 2013 A avaliação tecnológica abordou, além de aspectos técnicos, i.e., geração de energia, aspectos ambientais e econômicos da implantação da biodigestão nas destilarias, discutindo-se sua viabilidade e, por consequência, identificando-se as opções mais atrativas ao setor.…”