The use of high-sulfur crude oil in power generation plants has increased SO₂ emissions and reduced the service life of steam generators due to corrosive effects in the low-temperature zone, with consequent economic and environmental impacts. The introduction of SO₂ reduction technology using CaO requires an understanding of how the reacting system develops, its governing parameters, the stages controlling the reaction rate, and the kinetic model to which it conforms, among other critical aspects. The objective of this study was to determine the kinetic parameters characterizing the reaction between SO₂ and CaO at low temperatures, as described by the unreacted core model. In a laboratory-scale facility, the reaction temperature was set at 200, 300, and 400 °C, and the SO₂ concentration in air at 2%, 4%, and 6%. Gas-film resistance and gas diffusion within the solid bed were eliminated. The results showed that the rate-controlling step is the resistance of the product layer. SO₂ reduction increased with rising temperature and SO₂ concentration, and CaO conversion did not exceed 20%. The pre-exponential factor was 2.938 × 10⁻¹⁴ m²/s, and the activation energy was 17.23 kJ/mol, values characteristic of processes limited by physical diffusion.

Seventy-five thermophilic fungi capable of growing at 45 °C were isolated from sugarcane bagasse samples and cultivated under solid-state fermentation (SSF). Two isolates showing the highest xylanase and cellulase production were selected and identified as Aspergillus fumigatus 5S2 and Aspergillus sp. 1.6C. Water hyacinth (WH) and sugarcane bagasse (SCB) were evaluated as lignocellulosic supports and carbon sources for enzyme production under SSF. Eight culture conditions were evaluated to identify the most suitable condition for enzyme production. Results revealed that substrate recalcitrance was a major limiting factor for enzyme production and that thermochemical pretreatment significantly improved substrate utilization. The highest enzyme activities were achieved on pretreated WH (PWH) supplemented with NaNO₃ and mineral salts. A. fumigatus 5S2 reached 810 U/g dry matter (DM) for xylanase and 95 U/g DM for cellulase, whereas Aspergillus sp. 1.6C reached 649 U/g DM of xylanase and 33 U/g DM of cellulase under the corresponding optimal culture conditions. PWH was mixed with SCB to improve the physical properties of the SSF support, including aeration, porosity, and water retention. The highest enzyme production levels were obtained using 1:1 and 1:0.5 (w/w) mixtures of PWH and SCB for A. fumigatus 5S2 and Aspergillus sp. 1.6C, respectively. SSF column bioreactors packed with these mixtures produced similar enzyme titers at 30 °C and 40 °C, confirming the thermotolerant nature of both strains.

La purificación de enzimas celulasas constituye un paso crítico para su producción debido a que a menudo resulta ser muy costoso. El objetivo de este estudio fue evaluar la precipitación salina de celulasas producidas por Aspergillus niger UC33 en fermentación en estado sólido, para incrementar el rendimiento y pureza de la enzima con el menor costo posible. Se empleó el programa Design-Expert 11.1.2 para el diseño experimental y la optimización de las condiciones experimentales. El sulfato de amonio se utilizó para la precipitación entre 60 y 90 % de saturación, se emplearon entre 1 y 3 h de precipitación y las temperaturas utilizadas fueron 4 y 25 °C. Las condiciones óptimas encontradas para maximizar el rendimiento y la pureza fueron 68,97 % de saturación con sulfato de amonio, tiempo de precipitación de 1,28 h y temperatura de 25 °C. En estas condiciones los valores de rendimiento, pureza y costo, fueron: 74,81 %, 1,26 y USD $ 0,2609, respectivamente. El peso molecular de la enzima fue 38,47 kDa y la actividad celulolítica fue de 31,854 UI.

At present, lignocellulosic biomass and especially agro-industrial by-products have ceased to be considered solid residues, to become potential raw materials for various processes. In this sense, the present work aims to analyze technological alternatives for obtaining microbial oil in a pilot facility, through simulation in SuperPro Designer simulator, in order to implement a process that is technically, economically and environmentally efficient. Starting from a previous experimental work, where the best results for the cell growth stage were obtained at a C/N ratio of 100 and a fermentation time of 72 hours. The technological design of a base case of a plant for the production of microbial oil was based on the process designed by Vieira (2016) 1 and simulated as technological alternatives to obtain microbial oil by submerged fermentation (alternative 1) and solid-state fermentation (alternative 2). Technical, economic and environmental analyzes of each technological alternative were performed, obtaining the best results for alternative 2, in which a production of 614.9 liters of oil per year is obtained, a productivity of 2.66 g/Lh, and a unit cost of 224.25 €/L. In addition the filtered residues can be recycled, or can be used as a feedstock for animal feed production.