Application of process system engineering tools to the fed-batch production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from a vinasses-molasses Mixture.

Fed-batch production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer using vinasses-molasses mixture is carried out in this work by implementing different process systems engineering tools. Two fed-batch strategies are tested experimentally at 5 L scale, considering only offline information: (1) offline optimizing control and (2) exponential feeding. Application of these strategies showed that different feeding profiles result in different dynamic behaviour, influencing both, yield and biopolymer properties. As offline-based feeding strategies do not consider information of the culture status, they cannot deal with uncertainties. Therefore, a closed loop control strategy was implemented, which uses biomass and substrate information predicted online by soft-sensors. Results demonstrated the technical feasibility to produce biopolymer using a 75/25%vol. vinasses-molasses mixture. Successful implementation of the soft-sensor-based control strategy was evidenced at pilot plant scale, where sugar concentration was kept almost constant for 14 h, while obtaining the desired copolymer. Thus, proposed control strategy could be of interest at industrial-scale.

Producción de etanol a partir de yuca en condiciones de alta concentración de sólidos (VHG) / Ethanol production from cassava using very high gravity conditions (VHG)

La investigación realizada evalúa el efecto del medio fermentativo y la concentración de azúcares iniciales sobre la producción de etanol en sistemas batch, cuando se emplean sacarificados de harina de yuca (Manihot esculenta), como fuente de carbono. El diseño experimental ejecutado fue de tipo bifactorial de efectos fijos y analiza la productividad de bioetanol en cuatro medios fermentativos diferentes, dos de los cuales se suplementaron con sacarificados de harina de yuca variedad Copiblanca. Las concentraciones de azúcares iniciales evaluadas en estos sustratos fueron de 250, 300 y 350 g/L. Estos tratamientos fermentativos fueron inoculados con una variedad etanologénica comercial de S. cerevisiae a una concentración de 0.05% (p/v). Las condiciones de proceso incluyeron un volumen final de 150 mL, una incubación a 35°C por 48 horas, agitación constante de 150 rpm y pH entre 4.0 y 4.5. Los sacarificados provenientes de esta variedad de yuca usados como fuente de carbono, mostraron ser excelentes sustratos para la obtención de etanol. Se evidenciaron aumentos de más del 500% en términos de productividad volumétrica con respecto al control experimental y se alcanzaron concentraciones finales de etanol del 14.7%v/v, asociadas a rendimientos producto/sustrato de 0,48 g/g y productividades de 2,4 g/L/h. Estos parámetros cinéticos fueron logrados con el medio fermentativo más simple evaluado, medio compuesto por los sacarificados como fuente de carbono y como única fuente nutricional, bajo concentraciones de azúcares iniciales de 250g/L; lo que demuestra la aptitud de estos sustratos para efectos de producción etanólica.

This research exposes the fermentative medium and initial sugar concentration effect on ethanol production in batch systems, when used glucose syrups derivatives of cassava (Manihot esculenta), as a carbon source. The experimental design was factorial and analyzes the productivity of bioethanol in four different fermentation media, two of which were supplemented with cassava flour sugared. The initial sugar concentrations tested on these substrates were 250, 300 and 350 g / L. These fermentative treatments were inoculated with a commercial ethanolic variety of S. cerevisiae at a concentration of 0.05% (w / v). The process conditions included a final volume of 150 mL, incubation at 35 ° C for 48 hours , constant stirring at 150 rpm and pH between 4.0 and 4.5. The saccharified from this cassava variety showed be excellent substrate for the bioethanol production, achieving increases of 550% in terms of volumetric productivity over the control experiment, the above, allowed us to achieve final concentrations of ethanol of 14.7% v / v, yields product / substrate of 0.5 g / g, and productivities of 2.4 g / L / h. Most interesting is that these kinetic parameters were achieved with the simplest fermentation medium evaluated, the mean was compound of saccharified as a carbon source and as a sole source of nutrition, and its initial concentration of sugars was 250g / L; the above shows the ability of these substrates for ethanol production purposes.