A short-cut method for batch distillation columns working at constant reflux was applied to solve a problem of four components that needed to be separated and purified to a mole fraction of 0.97 or better. Distillation columns with 10, 20, 30, 40, and 50 theoretical stages were used; reflux ratio was varied between 2 and 20. Three quality indexes were used and compared: Luyben's capacity factor, total annual cost, and annual profit. The best combinations of theoretical stages and reflux ratio were obtained for each method. It was found that the best combinations always required reflux ratios close to the minimum. Overall, annual profit was the best quality index, while the best combination was a distillation column with 30 stages, and reflux ratio's of 2.0 for separation of benzene (i), 5.0 for the separation of toluene (ii), and 20 for the separation of ethylbenzene (iii) and purification of o-xylene (iv).

The objectives this study were to examine the integrated use of oil–coagulant for the direct extraction of coagulant from Moringa oleifera (MO) with 5% and 10% (NH4)2SO4 extractor solution to harvest Scenedesmus obliquus cultivated in urban wastewater and to analyze the oil extracted from MO and S. obliquus. An average content of 0.47 g of coagulant and 0.5 g of oil per gram of MO was obtained. Highly efficient algal harvest, 80.33% and 72.13%, was achieved at a dose of 0.38 g L−1 and pH 8–9 for 5% and 10% extractor solutions, respectively. For values above pH 9, the harvest efficiency decreases, producing a whitish water with 10% (NH4)2SO4 solution. The oil profile (MO and S. obliquus) showed contents of SFA of 36.24–36.54%, monounsaturated fatty acids of 32.78–36.13%, and polyunsaturated fatty acids of 27.63–30.67%. The biodiesel obtained by S. obliquus and MO has poor cold flow properties, indicating possible applications limited to warm climates. For both biodiesels, good fuel ignition was observed according to the high cetane number and positive correlation with SFA and negative correlation with the degree of saturation. This supports the use of MO as a potentially harmless bioflocculant for microalgal harvest in wastewater, contributing to its treatment, and a possible source of low-cost biodiesel.

This work present the batch distillation shortcut methods developed from the Fenske-Underwood-Gilliland (FUG) method of continuous distillation. In addition, a comparison between the results of shortcut method developed by Diwekar and Narváez-García et al. is done. The results of both methods are compared for validation with the results using the rigorous method presented by Domenech and Enjalbert. The results indicate no significant differences in both shortcut methods being the maximum deviation found between the two shortcut methods is less than 3%. Then, the use of any of both methods is in the ease or difficulty of the solution each of the model equations. Both methods were implemented using Fortran programming. Multdistbatch © software was used for the rigorous method.

Background:Microalgae remove nutrients from wastewater with the possibility of grow in mixotrophic and heterotrophic cultures. However, the effluent quality can modify the profile of fatty acids and biodiesel quality.Methods:Phototrophic and mixotrophic (light / dark; 12/12 h) cultures ofScenedesmus obliquuson domestic wastewater (WW) and Artificial Wastewater (AW) was carried out to evaluate the lipid accumulation and fatty acid methyl esters profile. The microalgae was first cultivated in an enriched medium (90 mg N-NH4 L-1) and subsequently under nitrogen limitation (30, 20 and 10 mg N L-1) using a two-stage process for both culture media.Results:A higher cell density in enriched AW medium was obtained in phototrophic and mixotrophic culture of 19 x 106cell mL-1and 20 x 106cell mL-1, respectively; than for WW (13 x 106cell mL-1and 14 x 106cell mL-1, respectively). The nitrogen limitation (from 90 to 20 mg N L-1) for AW increased the lipid content by 5.0% and 17.28% under phototrophic and mixotrophic conditions, respectively and only 5% for WW in mixotrophic culture.Conclusion:The high Cetane Number (CN) show a positive correlation with high Saturated Fatty Acids (SFA) content and negative correlation with the Degree of Saturation (DU), suggesting a good ignition of fuel. The Cold Filter Plugging Point (CFPP) (-6.02 to -8.45 °C) and Oxidative Stability (OS) (3.53 - 6.6 h) propose toScenedesmus obliquusas a candidate in the production of biodiesel and potential application for an integral urban wastewater treatment system.

Modelado de la biodegradación en biorreactores de lodos de hidrocarburos totales del petróleo intemperizados en suelos y sedimentos (Biodegradation modeling of sludge bioreactors of total petroleum hydrocarbons weathering in soil and sediments)

In this work we analyzed different biochemical parameters such as cell growth, nitrogen removal, lipid productivity and fatty acid profile in Chlorella vulgaris by hydrodynamic effect varying the aeration to (0.75, 1.25, 1.75, 2.25) vvm and white light conditions continuous in column photobioreactor; hydrodynamic calculations of the FBR were carried out to determine the shear rate and possible existence of hydrodynamic stress at the proposed aeration conditions; the values reached in the shear rate were reduced (0.0025 to 0.0220) s-1, observing flow of homogeneous type in all the experiments; however, the maximum values of cell growth and specific growth rate (μ) were (5.90x106 cells mL-1 and 0.0229 d-1) respectively, as well as the highest N consumption (60%) and the highest productivity of lipids (8.98 mgL-1d-1) were reached during the experiment at 0.75 vvm. In relation to the analysis of the fatty acid profile greater presence of polyunsaturated fatty acids (PUFA) was observed in the experiments at 0.75 vvm, 1.75 vvm and 2.25 vvm, however, at 1.25 vvm, higher productivity of saturated fatty acids (SFA) was obtained; with respect to monounsaturated fatty acids (MUFA) the highest concentration was reflected at 0.75 vvm. The components with the highest presence in the fatty acid profile analysis were C12: 0; C20: 5N3; C24: 1; C 22: 0; C22: 2.

Modelado de la biodegradación en biorreactores de lodos de hidrocarburos totales del petróleo intemperizados en suelos y sedimentos (Biodegradation modeling of sludge bioreactors of total petroleum hydrocarbons weathering in soil and sediments)

Fermentation technologies have been developed to improve the production of ethanol and an alternative is the immobilization technology, which ofers the possibility of eiciently incorporating symbiotic bacteria in the same matrix. This study analyzes the potential use of immobilized and coinmobilized systems on beads of calcium alginate for ethanol production used mango waste (Mangifera indica) by Zymomonas mobilis and Saccharomyces cerevisiae compared with free cells culture and evaluate the efect of glucose concentration on productivity in coimmobilized system using a Chemostat reactor Ommi Culture Plus. For free cell culture, the productivity was higher for Z. mobilis ). The conversion of glucose to ethanol for coimmobilized system was higher (6.91 mol ethanol) with 50 g L -1 of glucose compared to 200 g L -1 of glucose (5.82 mol ethanol); suggesting the immobilized and coimmobilized cultures compared with free cells ofer an opportunity for the reuse of organic residues and high alcohol production.