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Los biocombustibles se han identificado como una estrategia que contribuye a la recuperación económica sostenible. Los biocombustibles se generan a partir de biomasa, y permiten generar energía eléctrica y/o térmica, así como energía motriz, la cual es de gran relevancia para el sector transporte, en el que se requieren principalmente biocombustibles líquidos. La producción de biocombustibles líquidos es factible técnicamente, pero su factibilidad financiera es aún un reto. Por ello, en este trabajo se presentan las rutas de procesamiento para obtener biogasolina, biodiésel, diésel verde y bioturbosina, así como las estrategias de la intensificación de procesos con mayor potencial de aplicación; en éstas se incluyen columnas de destilación térmicamente acopladas, destilación reactiva, así como extracción reactiva.

In this research, effect of productive stages in nitrogen and phosphorus excretion in wastewater from hyperintensive tilapia (Oreochromis niloticus) culture was evaluated. Fish were cultivated considering three development stages (fingerling of 1.79 g, juvenile of 36.13 g, and adult of 72.96 g). Nitrite, nitrate, ammonium, and phosphorus concentration were determined in order to know the amount of nutrients excreted per productive stage of the fish at a high stocking density. Biometric data were recorded during the experiment with the purpose of determining the growth behavior of fish, as well as the measurement of the aerobic metabolism. Results showed that survival, growth, and health of fish are not affected by hyperdensity of culture; as well, combined catabolism of proteins and lipids was presented as substrates for energy with value for O:N ratio ranging between 20 and 60. In addition, higher concentration in excretion of nitrogen compounds and phosphorus per gram of fish was recorded in wastewater from a hyperintensive culture in fingerlings than in juveniles and adults. These results suggest the use of this wastewater in the early stages of fish growth, aiming to enhance sustainable systems with maximum use of the resources, such as aquaponics systems. HIGHLIGHTS The effect of productive stages in NP excretion in wastewater from hyperintensive tilapia culture are evaluated.; Survival, growth and health is not affected by hyperdensity of culture.; Concentration in NP excretion per gram of fish is higher in fingerlings.; It is suggested the use of aquicultural wastewater in the early productive stages for the use in sustainable systems such as aquaponics systems.

Resumen Los residuos agrícolas representan un problema de contaminación, dada su inadecuada disposición y elevados volúmenes generados. Por ello, su revalorización para producir biocombustibles es atractiva, para lo cual se requiere conocer su poder calorífico. Se han reportado modelos matemáticos para predecir el poder calorífico considerando análisis elementales, estructurales y proximales, siendo éstos últimos los de menor costo. Por ello, el presente trabajo realizó un estudio comparativo de los modelos matemáticos que predicen el poder calorífico con base en análisis elementales; dicho estudio considera: 1) residuos agrícolas procedentes de México (paja de frijol, paja de trigo, cascarilla de arroz, cascabillo de café), y 2) residuos reportados en la literatura (fibras y cáscaras de coco, residuos de jardín, cáscaras de canola, cáscaras de Jatropha curcas, paja de trigo), con el objetivo de determinar si los modelos existentes funcionan adecuadamente para las biomasas mexicanas. Para ello, las biomasas mexicanas son caracterizadas mediante análisis proximales; por otra parte, se estima el poder calorífico de todas las biomasas con modelos matemáticos lineales previamente reportados, y los resultados se comparan con los valores experimentales. Los resultados muestran que los coeficientes de determinación de los modelos matemáticos existentes son bajos, en particular al emplear datos de biomasas mexicanas. El mejor modelo para predecir el poder calorífico en residuos agrícolas mexicanos (R2 = 0.72) considera solamente el contenido de materia volátil y de carbono fijo, así como una débil funcionalidad del contenido de cenizas. Por ello, es necesario proponer modelos matemáticos específicamente para las biomasas mexicanas. Abstract Agricultural residues represent a pollution problem because they are inadequately disposed of and high volumes of these wastes are generated. Therefore, revaluating them to produce biofuels is attractive, but, for that purpose, their calorific value should be established. Some mathematical models reported in the literature to predict calorific value have considered elemental, structural, and proximal analyses, the latter being the least expensive type. This article compares different mathematical models that have been used to predict calorific value based on elemental analysis in order to 1) evaluate agricultural residues from Mexico (bean straw, wheat straw, rice husks, and coffee husks) and other residues reported in the literature (coconut fibers and husks, garden waste, canola hulls, Jatropha curcas husks, and wheat straw) and 2) determine if the existing models work adequately for Mexican biomasses. Thus, Mexican biomasses were characterized using proximal analyses, and the calorific value of all the biomasses was estimated employing previously reported linear mathematical models. The results, which were compared with experimental values, show that the coefficients of determination of the existing mathematical models are low, particularly when Mexican biomass data are used. The best model to predict the calorific value of Mexican agricultural residues (R2 = 0.72) considers only the content of volatile matter and fixed carbon, in addition to a weak functionality of the ash content. Consequently, mathematical models should be proposed specifically for Mexican biomass.

México es uno de los principales productores de zarzamora en el mundo y este fruto es uno de los cultivos nacionales con mayor demanda en el extranjero. Sin embargo, su corta vida de anaquel y las condiciones especiales de almacenamiento que requiere para conservarse representan un reto constante para llevarla a partes lejanas del mundo. Hasta el momento, los esfuerzos para su conservación se han enfocado en estrategias que se aplican después de la cosecha del fruto; no obstante, estos métodos tienen limitaciones. Por lo tanto, el objetivo de este artículo es abordar una propuesta reciente relacionada al manejo de la zarzamora previo a su cosecha, como una herramienta para lograr su exitosa comercialización a nivel internacional.

Agro-industrial residues represent more than 60% of organic wastes worldwide, which could be used to generate other by-products or to be incorporated into other production chains. For example, bagasse is a waste from the tequila industry in Mexico that could be implemented for mushroom cultivation. Additionally, the substrate influences the growth, development, and production of secondary metabolites of fungi. This work presents a comparative experiment that studies the metabolite production in Pleurotus djamor mushrooms on agave bagasse and barley straw (traditional substrate). The biological efficiency (BE), yield, phenolics and flavonoids, antioxidant capacity, tannins, and the identification of low molecular weight metabolites were evaluated. Five treatments were proposed according to the following mixtures of agave bagasse: barley straw: T1 (1:0), T2 (3:1), T3 (1:1), T4 (1:3), and T5 (0:1). T2 had the highest yield (13.39 ± 3.23%), BE (56.7 ± 13.71%), and flavonoids (44.25 mg rutin equivalent (RE)/g); T3 obtained the highest phenol content (230.27 mg GAE/g); and T1 the highest tannins content (0.23 mg (+) catechin equivalent (CE)/g). Finally, T1 and T5 are the ones that present the greatest number of primary metabolites, including hydroxycitric acid, 2-deoxy-D-galactose, D-mannose, paromomycin, palmitic acid, pyrrole, mannitol, and DL arabinose, while in T2, T3, and T4 only two chemical compounds were found present (palmitic acid and pyrrole in T2, silicic acid and pyrrole in T3 and 2-deoxy-D-galactose and quinoline in T4). The cultivation substrate influences the concentration of bioactive molecules in the fruiting bodies of P. djamor. Additionally, P. djamor’s degradation of agave bagasse residue generates a potential application for agro-industrial residue management at a low cost.

In this work, the production and characterization of pellets made from rice husks and wheat straws is presented. For this, physicochemical and energetic characterization of pellets produced with rice husks and mixtures of rice husks with wheat straws were carried out, followed by a comparison with those properties stablished by the ISO 17225-6 standard. The rice husk pellets exhibited the lowest calorific value (3090.64–4049.05 kcal/g) and highest ash content (12.81–17.51%), while the pellets made from mixtures obtained the highest calorific power (4301.10–4573.50 kcal/g) and a reduced amount of ashes (11.43–13.06%). Moreover, the pellets produced with both biomasses exceed the moisture, ashes and nitrogen content, but complied with diameter, length and durability components. These results suggest that these biomasses blends improve the quality and combustion characteristics of the pellets, aiming to enhance the research for the manufacturing of these sustainable biofuels.

The safety of the process plant depends on the adequate separation between the assets and the hazardous units, along with the installation of protection devices. Several mathematical approaches have been proposed to reduce the risk of the explosions through the solution of the facility layout problem, but no model has included the design of the safety instrument systems. In this work, a MINLP approach was developed to solve three issues at the same time: the process equipment layout, the facility layout, and the safety instrumented system design. This approach aims to find the optimal facility layout that minimizes the land cost, the pipeline cost, and the lifecycle cost of each safety instrumented system, reducing the risk of explosions and keeping safety as much as possible the plant assets. The model was applied to find the optimal facility layout of ethylene oxide plant for different tolerable risk frequencies. In this way, this approach provides valuable information during the design stage and substantial support for decision-makers.

The biojet fuel production has been considered a promising strategy to partially satisfy the aviation fuel demand. Recently, the biojet fuel obtained from the alcohol-to-jet (ATJ) process has been certified by the American Society of Testing Materials (ASTM). In this work, the modelling and simulation of the ATJ conventional process is presented, considering as raw material bioethanol produced from lignocellulosic wastes. To reduce the energy requirements and the environmental impact, process intensification tools are applied on the separation zone, followed by the energy integration of the whole process. The ATJ conventional and intensified-integrated processes are assessed by the total annual cost (TAC) and the CO2 emissions. According to the results, the intensification on the separation zone allows reducing energy requirements by 5.31 % in contrast to the conventional sequence; moreover, the energy integration of the intensified process reduces by 34.75 % and 30.32 % the heating and cooling requirements, respectively; as consequence, TAC and CO2 emissions are decreased by 4.83 % and 4.99 %, respectively, when compared to the conventional process. Nevertheless, the electricity generated by the turbines completely satisfies the electrical energy requirement of the process.

In the transport sector, aviation has the higher growth rate; this implies that more fuel is going to be required and more carbon dioxide is going to be emitted. Thus in order to have a sustainable development of the aviation sector, specific strategies have been proposed; one of these is the use of renewable aviation fuel, which has been identified as the most promissory. Renewable aviation fuel has gained the attention of the scientific and technological community, who have reported its production from different types of biomass through several conversion routes, and even in biorefinery schemes. Moreover, some studies have been realized about the decreasing in the energy consumption of the production processes. All these efforts contribute to the development of sustainable processes for the production of renewable aviation fuel. However, the production of renewable aviation fuel at industrial scale also depends on other factors related to legislation, governmental support, supply chain, and productive potential of the raw materials. Therefore in this work the opportunities and challenges for the establishment of the production of renewable aviation fuel at industrial scale are discussed. The chapter will focus on the most promissory raw materials, certified pathways to produce biojet fuel, current research and development in production processes, and advances in commercialization along with the supply chain for the production of biojet fuel.

Renewable aviation fuel is the most promising alternative to reduce emissions in the aviation sector; its production is technically feasible, but not its cost respect to fossil jet fuel. Then, novel pathways need to be developed. One option is the processing through a biorefinery scheme, where biomass is completely converted to several products. Thus, in this work the computer-aided design and analysis of an integrated biorefinery for the conversion of Jatropha curcas fruit, castor bean plant, microalgae biomass and cooking oil is presented; the biorefinery is planned to produce aviation biofuel and other biofuels. The conversion processes are modelled and simulated using Aspen Plus. The assessment of the biorefinery is realized through the estimation of total annual cost, released CO2 emissions, and the net gross profit. Results indicated that biojet fuel represents 33% of net gross profit, with 5.52 kW invested per kW of energy delivered by the products.

The environment depletion caused by the intensive use of fossil fuels to produce electricity to satisfy the increasing demands has motivated the searching of alternative energy sources. In this context, residual biomass from different crops has been considered as alternative. However, there are significant issues associated to this energy source, which are mainly related to the low density and high transportation costs. Therefore, in this paper is presented an optimization approach for the strategic planning for the use of waste biomass pellets in power plants for electric energy production. The proposed approach considers all the activities included in the supply chain since the collection of residues until the combustion of pellets in power plants. Particularly, the location and design of the pelleting plants in a macroscopic region, as well as the selection of biomass and transportation routes are considered to satisfy the needs of the power plants at the minimum cost and minimum environmental impact. A case study for the national case of Mexico is presented, where the results show that is possible to satisfy 50% of the national demand of the power plants through the use of residual biomass, and simultaneously the associated CO2 emissions can be reduced 25%.

The layout design for storage vessels is an important issue to keep safe process plants, since the accidents originated in storage areas are almost one-third of all reported accidents. In order to reduce fire and explosion damages different mathematical approaches have been proposed; however, most of them are not suitable for real storage facilities design. In this work, a MILP approach has been developed to find the optimal layout of storage vessels, seeking to minimize the cost associated with potential damage of fire and explosion. This approach allows allocation of suitable sites for storage vessels, reducing accidents propagation, and domino effect while keeping safety as much as possible the plant assets. In this way, the optimization approach provides substantial support for decision-makers during the design stage. The study case used to test the mathematical model considers 19 vessels, six buildings, five process facilities and 25 possible scenarios, which includes 16 fires and 9 explosions.

Micro-algae are photosynthetic organisms, which represent a promissory renewable raw material for biofuels production, since they can be cultivated in non-fertile lands, avoiding the competition with food crops for land use. From micro-algae, oil can be obtained oil that can be converted to biodiesel, green diesel and biojet fuel. In particular, the renewable aviation fuel is one of the less explored biofuels; nevertheless, for the aviation sector, this is the best alternative to reduce CO2 emissions, allowing its sustainable development. In order to produce hydrocarbons in the boiling point range of jet fuel, we need to transform the micro-algae oil. A number of research projects report the use of micro-algae oil for the production of biojet fuel through the hydrotreating process. However, the application of process intensification strategies for the hydroprocessing of micro-algae oil has not been reported. Therefore, in this work we propose the modeling, simulation and intensification of the hydrotreating process to produce biojet fuel, considering micro-algae oil as raw material. The hydroprocessing of micro-algae oil is modeled in Aspen Plus processes simulator, based on data from an experimental study recently reported. The produced renewable hydrocarbons are purified through conventional and intensified distillation sequences; thereby, conventional and intensified hydrotreating processes are defined and evaluated in terms of total annual costs, CO2 emissions and biojet fuel price. Simulation results show that the implementation of intensification strategies leads to the production of biojet fuel with reduced carbon dioxide emissions, 34% less, and a competitive price per liter, 78% cheaper than fossil jet fuel price.