ABSTRACT Vinasses are a very harmful residue of the alcohol distillation, their discharge into soil and water can cause negative environmental impacts if the appropriate treatments do not take place. Anaerobic digestion has shown to be the best technological and economical method to treat this residue, thus bioenergy can be generated as by-product of this process. Nevertheless, the slow adaptation of the microbial consortium in inoculum (activated sludge) to the substrate (mezcal vinasses) is very important to enhance the efficiency of the biogas and methane production, as well as organic matter removal. In this work, the adaptation process of the anaerobic digestion of mezcal vinasses was carried out in a 30-day period. Inoculum (activates sludge) and vinasses were mixed initially at the ratio 7:3. The feeding steps were done every seven days replacing 30 % of the total volume with new vinasses. Biogas was quantified and qualified. Biogas production reached 217 L/kgVSvinasses generating a daily methane content between 50 and 55 % by the end of the adaptation period. The organic matter removal efficiency was almost seven times higher at the end of the adaptation, in comparison to the beginning. This suggests that a slow adaptation process enhance the organic matter removal and eventually other pollutants in vinasses. When comparing this results with the literature, biogas and methane production were similar, nevertheless the anaerobic digestion could be optimized, in order to increase the methane content in biogas and the removal rate of organic matter.

RESUMEN Las vinazas son un residuo proveniente de la destilación de alcohol, su descarga en suelos y aguas puede causar impactos ambientales negativos si no se realizan los tratamientos adecuados antes de considerar su descarga. La digestión anaerobia ha demostrado ser un método con ventajas tecnológicas y económicas para tratar este residuo y generar bioenergía al mismo tiempo. Sin embargo, una lenta adaptación del consorcio microbiano contenido en el inóculo (lodo activado) al sustrato (vinazas del mezcal) es muy importante para mejorar la eficiencia de la producción de biogás y metano, así como la reducción de materia orgánica. En este trabajo, el proceso de adaptación de la digestión anaerobia de las vinazas se llevó a cabo en un período de 30 días. El inóculo (lodo activado) y las vinazas se mezclaron inicialmente en una proporción 7:3. El reactor se alimentó cada siete días reemplazando 30 % del volumen total del reactor con vinazas. La producción de biogás alcanzó 217 L/kgVSvinazas con un contenido de metano de 50 a 55 %. La eficiencia de eliminación de materia orgánica fue casi siete veces mayor al final de la adaptación en comparación con el comienzo. Esto sugiere que una adaptación lenta mejora la reducción de materia orgánica y eventualmente otros contaminantes. Al comparar estos resultados con la literatura, la producción de biogás y metano fue similar, sin embargo, la digestión anaerobia podría optimizarse con el fin de aumentar el contenido de metano en el biogás y reducir la materia orgánica en el sustrato.

ABSTRACT Vinasses are one of the main wastes generated from the mezcal industry in Mexico. Due to their high organic matter content and low pH, vinasses have negative environmental impacts if discharged without any treatment. An alternative treatment of vinasses is their use in microbial fuel cells (MFC) for organic matter removal and electricity production. In this paper, the performance of a MFC using vinasses is analyzed. Different organic matter concentrations in terms of chemical oxygen demand (COD) were tested and compared regarding power density, internal resistance, and voltage production. The results demonstrated that the highest COD tested resulted in a poor MFC performance. When using vinasses in MFC for 10 days, COD of 6000 mg/L generated 80.64 W/m3 and when using vinasses with a COD of 17 143 mg/L, the power density dropped to 5.13 W/m3. Further tests of COD performance in MFC were made with 10 640 and 6760 mg/L for 68 days. It was demonstrated that a COD of 10 604 mg/L only produced 0.61 V, while a COD of 6760 mg/L reached 0.81 V. Regarding the organic matter removal, the highest COD removed (92 %) was obtained when using vinasses with a COD of 10 604 mg/L. By operating the cell with 6000 mg/L, COD removal was 83 % and with 17 143 mg/L, 49 %. To achieve a better MFC performance, the organic matter content in the electrolyte should not exceed 6000 mg/L so that the MFC does not achieve a saturated state that hinders the oxidation mechanisms and thus electricity production and COD removal.

RESUMEN Las vinazas son uno de los principales residuos generados por la industria del mezcal en México. Debido a su alto contenido de materia orgánica y bajo pH, las vinazas tienen impactos ambientales negativos si se descargan sin tratamiento alguno. Un tratamiento alternativo de las vinazas es su utilización en celdas de combustible microbianas (CCM) para la disminución de materia orgánica y la producción de electricidad. En este trabajo se analiza el rendimiento de una CCM operada con vinazas. Diferentes concentraciones de materia orgánica en términos de demanda química de oxígeno (DQO) se utilizaron y compararon con respecto a la densidad de potencia, resistencia interna y la producción de voltaje. Los resultados demostraron que la DQO más alta, dio como resultado un pobre rendimiento de la CCM. Al utilizar las vinazas en la CCM durante 10 días, una DQO de 6000 mg/L generó 80.64 W/m3 y utilizando las vinazas con una DQO de 17 143 mg/L, la densidad de potencia se redujo a 5.13 W/m3. Otras pruebas de rendimiento de la DQO en la CCM se llevaron a cabo por 68 días con DQO de 10 640 y 6760 mg/L. Se demostró que una DQO de 10 604 mg/L sólo produjo 0.61 V, mientras que una DQO de 6760 mg/L alcanzó 0.81 V. En cuanto a la remoción de materia orgánica, la mayor remoción de DQO (92 %) se obtuvo utilizando vinazas en la CCM con 10 604 mg/L de DQO. Utilizando una DQO de 6000 mg/L, la remoción de DQO fue del 83 % y con 17 143 mg/L, fue del 49 %. Para lograr un mejor rendimiento de la CCM, el contenido de materia orgánica en el electrolito no debe exceder 6000 mg/L de manera que la celda no alcance un estado saturado que obstaculice los mecanismos de oxidación y por lo tanto la producción de electricidad y la remoción de la materia orgánica.

Abstract The positive accepted savoury taste of rye bread is dependent on acetate concentration in the dough of such breads. In order to study how calcium acetate influences rye bread properties, the pH of rye doughs fortified with calcium acetate and the resulting volume of the breads were measured. Furthermore, CO2 formation of yeast with added calcium acetate and yeast with different pH levels (4, 7, 9) were measured. Thereby, it was determined that the addition of calcium acetate increased the pH of dough from 4.42 to 5.29 and significantly reduced the volume of the breads from 1235.19 mL to 885.52 mL. It could be proven that bread volume was affected by a 30.9% lower CO2 amount production of yeast, although bread volume was not affected by changing pH levels. Due to reduced bread volume, high concentrations of calcium acetate additions are not recommended for improving rye bread taste.

Os efeitos de diferentes níveis de déficit hídrico, aplicados durante o desenvolvimento da canola, foram avaliados por meio de um experimento conduzido em vasos de metal no interior de uma casa de vegetação, no Departamento de Engenharia Agrícola, da Universidade de Kassel, Alemanha. Foi utilizado um delineamento inteiramente casualizado, com a cultivar Ability (Summer Rape), e três níveis de déficit de água, 0%, 30%, 60% da evapotranspiração da cultura, totalizando três tratamentos com 20 repetições. O manejo da irrigação foi realizado por meio do balanço hídrico diário, em que ET = I - D, onde ET é evapotranspiração, I é irrigação, D é drenagem. Foram realizadas semanalmente as seguintes avaliações: diâmetro do caule (mm), altura da planta (cm), número de folhas, número de ramos e número de síliquas. No final do experimento, foram avaliadas a matéria verde total (g planta-1) e matéria seca total (g planta-1), produtividade de grãos (g planta-1), além do teor de proteína (%) e de óleo (%) dos grãos. Os dados foram submetidos à análise de variância, sendo o efeito dos tratamentos estudado por meio de análise de regressão. Os resultados mostraram diferenças significativas entre os tratamentos para as variáveis analisadas, exceto para a altura das plantas e teor de proteína dos grãos, pelo teste F a 5% de probabilidade. O fator de resposta ky, indicador da sensibilidade da cultura ao déficit hídrico, foi menor que um para todos os parâmetros estudados. A produtividade de grãos apresentou a maior sensibilidade ao déficit hídrico.

Effects of different levels of water deficit applied during rapeseed crop development were assessed in a trial with metallic pots in greenhouse at the Department of Agricultural Engineering of Kassel University, Witzenhausen, Germany. A randomized block design was used with one cultivar (Ability Summer Rape) and three levels of water deficit (0, 30, and 60% of evapotranspiration) in three treatments and 20 replicates. Irrigation management was carried out through daily water balance, where ET = I - D; ET: evapotranspiration; I: irrigation; and D: drainage. The following evaluations were carried out weekly: stem diameter (mm); plant height (cm); number of leaves; number of branches and number of pods. At the end of the experiment, assessed total green matter (g plant-1), total dry matter (g plant-1), grain yield (g plant-1), grain protein content (%) and grain oil content (%) were also assessed. Data were submitted to variance analysis and the effect of the treatments was assessed by regression analysis. Results showed significant differences between the treatments in all analysed variables except for plant height and grain protein content, by test F at 5% probability. Factor of response ky, indicator of crop sensitivity to water deficit, was lower than one for all assessed variables. Grain yield showed the highest sensitivity to water deficit.