Attempting to associate waste treatment to the production of clean and renewable energy, this research sought to evaluate the biological production of hydrogen using wastewater from the cassava starch treatment industry, generated during the processes of extraction and purification of starch. This experiment was carried out in a continuous anaerobic reactor with a working volume of 3L, with bamboo stems as the support medium. The system was operated at a temperature of 36°C, an initial pH of 6.0 and under variations of organic load. The highest rate of hydrogen production, of 1.1 L.d-1.L-1, was obtained with application of an organic loading rate of 35 g.L-1.d-1, in terms of total sugar content and hydraulic retention time of 3h, with a prevalence of butyric and acetic acids as final products of the fermentation process. Low C/N ratios contributed to the excessive growth of the biomass, causing a reduction of up to 35% in hydrogen production, low percentages of H2 and high concentrations of CO2in the biogas.
The Brazil's Biodiesel Production and Use Program introduces biodiesel in the Brazilian energy matrix, bringing along the perspective of a growth of the glycerin offer, co-product generated in the proportion of 10 kg for each 100 L of biodiesel. The aim of this study was to evaluate the addition of crude glycerin in the anaerobic digestion of cassava starch industry effluent (cassava wastewater), in a horizontal semi-continuous flow reactor of one phase in laboratory scale. It was used a reactor with a 8.77 L of useful volume, a medium support for corrugated conduit of polyvinyl chloride (PVC), temperature of 261 ºC, fed with cassava wastewater and glycerin, with hydraulic detention times of 4 and 5 days and increasing volumetric organic load of 3.05; 9.32; 14.83 and 13.59 g COD L -1 d -1 , obtained with the addition of glycerin at 0; 2; 3 and 2% (v/v), respectively. The average removal efficiencies of TS and TVS were decreasing from the addition of glycerin to the cassava wastewater, averaging 81.19 to 55.58% for TS and 90.21 to 61.45% for TVS. The addition of glycerin at 2% increased the biogas production compared to the control treatment, reaching 1.979 L L -1 d -1 . The biogas production as a function of the consumed COD was higher for the control treatment than for the treatments with addition of glycerin, which indicates lower conversion of organic matter into biogas.KEYWORDS: cassava wastewater, biodiesel, biogas, glycerol. CODIGESTÃO ANAERÓBIA DE GLICERINA BRUTA E EFLUENTE DE FECULARIARESUMO: O Programa Nacional de Produção e Uso do Biodiesel introduziu o biodiesel na matriz energética brasileira, trazendo a perspectiva de aumento da oferta de glicerina, coproduto gerado na proporção de 10 kg para cada 100 L de biodiesel. O objetivo principal deste trabalho foi avaliar a adição de glicerina bruta na digestão anaeróbia de efluente de indústria de fécula de mandioca (manipueira), em reator de fluxo semicontínuo horizontal de uma fase, em escala de laboratório. Foi utilizado um reator com volume útil de 8,77 L, meio suporte em eletroduto corrugado de policloreto de vinila (PVC), temperatura de 261 ºC, alimentado com manipueira e glicerina, aplicando-se tempos de detenção hidráulica de 4 e 5, dias e cargas orgânicas volumétricas crescentes de 3,05; 9,32; 14,83 e 13,59 g COD L -1 d -1 , obtidas com a adição de glicerina aos níveis de 0; 2; 3 e 2% (v/v), respectivamente. As eficiências de remoção média de ST e STV foram decrescendo a partir da adição de glicerina à manipueira, com médias de 81,19 a 55,58 % para ST e 90,21 a 61,45% para STV. A adição de glicerina em 2% aumentou a produção de biogás em relação ao tratamentocontrole, chegando a 1,979 L L -1 d -1 . A produção de biogás em função da DQO consumida foi maior para o tratamento-controle que, para os tratamentos com adição de glicerina, indica menor conversão da matéria orgânica em biogás.
Fixed-bed reactors have been considered promise alternatives for hydrogen production due to their simple construction and increase in the biomass retention. The purpose of this study was to investigate the biological production of hydrogen in anaerobic fixed-bed reactors with cassava starch wastewater used as substrate. Different support materials and arrangements of fixed-bed were used to evaluate the biological production of hydrogen in anaerobic continuous fixed-bed reactors, with cassava starch wastewater as substrate -recycled low-density polyethylene scraps, in packed bed (R1), recycled low-density polyethylene cylinders, in ordained bed (R3) and bamboo stems, in vertical arrangement (R2 and R4). In R1 the initial pH was adjusted for 6.0, with hydraulic retention time (HRT) of 4 h and organic loading rate (OLR) of 9.5 g.L -1 .d -1 . In R2 the initial pH was maintained in 4.5, with HRT of 4 h and OLR of 9.5 g. -1 ) were verified in the reactors with bamboo stems. In R4, the increase of OLR and the reduction of the initial pH contributed to the increase of butanol concentration in 1.8 times, diminishing the VHPR in 41.68%, yield in 63.95% and H2 in 37.6%, and indicating that the effect of pH is more pronounced with the increase of OLR, leading to the solventogenesis.
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