El presente artículo tiene como objetivo realizar una revisión del impacto ambiental generado por los contaminantes emergentes (CE) en el entorno acuático y la manera de tratarlos, al ser descargados en los cuerpos hídricos. Se presenta una visión global y una visión a nivel regional (Latinoamérica) de los contaminantes emergentes presentes en el agua bien sea agua residual doméstica, agua residual industrial o agua potable para de esta manera identificar cuáles son los principales contaminantes emergentes (CE) y mostrar la importancia y el impacto que tienen sobre el ambiente y las repercusiones debidas al desconocimiento y la falta de legislación al momento de controlar los vertimientos sobre los cuerpos hídricos. Las eficiencias de remoción para los contaminantes emergentes mediante tratamientos comunes (coagulación, floculación, sedimentación, etc.) son medianamente aceptables con valores entre un 30% y 60% mientras que a través de tratamientos terciarios (oxidación avanzada, tratamientos con peróxido de hidrogeno, luz UV, etc.) alcanza porcentajes entre un 80% y un 95% indicando la alta capacidad para remover los contaminantes.

This study presents the analysis of the exergy load distribution in a separation process by extractive distillation for ethanol dehydration. The methodology carried out is divided into three parts: the calculation of the flow exergy considering the physical and chemical exergies of the distillation process; the calculation of the primary and transformed exergy contributions considering the consumed exergy; and finally, the overall process efficiency, which shows the real percentage of energy being used in the process. The simulation of an extractive distillation separation system is carried out using Aspen Plus^®, from Aspen Tech Version 9. In general, heat transfer processes (heating or cooling) are the ones that generate the greatest exegetic destruction, which is why they must be the operations that must be optimized. As a result of our case study, the local exergy efficiency of the extractive distillation column is 13.80%, which is the operation with the greatest energy loss, and the overall exergy efficiency of the separation system is 30.67%. Then, in order to increase exergy efficiency, a sensitivity analysis is performed with the variation of the azeotrope feed, number of stages, reflux ratio, and solvent feed variation on ethanol purity to reach an overall efficiency of 33.53%. The purity of ethanol is classified as higher than that of the specified, 99.65%.

Agro-industrial wastes are an energy source for different industries. However, its application has not reached small industries. Previous and current research activities performed on the acidogenic phase of two-phase anaerobic digestion processes deal particularly with process optimization of the acid-phase reactors operating with a wide variety of substrates, both soluble and complex in nature. Mathematical models for anaerobic digestion have been developed to understand and improve the efficient operation of the process. At present, lineal models with the advantages of requiring less data, predicting future behavior and updating when a new set of data becomes available have been developed. The aim of this research was to contribute to the reduction of organic solid waste, generate biogas and develop a simple but accurate mathematical model to predict the behavior of the UASB reactor. The system was maintained separate for 14 days during which hydrolytic and acetogenic bacteria broke down onion waste, produced and accumulated volatile fatty acids. On this day, two reactors were coupled and the system continued for 16 days more. The biogas and methane yields and volatile solid reduction were 0.6 ± 0.05 m3 (kg VSremoved)−1, 0.43 ± 0.06 m3 (kg VSremoved)−1 and 83.5 ± 9.8 %, respectively. The model application showed a good prediction of all process parameters defined; maximum error between experimental and predicted value was 1.84 % for alkalinity profile. A linear predictive adaptive model for anaerobic digestion of onion waste in a two-stage process was determined under batch-fed condition. Organic load rate (OLR) was maintained constant for the entire operation, modifying effluent hydrolysis reactor feed to UASB reactor. This condition avoids intoxication of UASB reactor and also limits external buffer addition.

Anaerobic digestion (AD) is an important step in waste recovery. In Colombia, the production of citrus food significantly contributes to environmental impact via waste generation. In 2021, the waste produced, specifically citrus rind, amounted to 725,035 tons/year. During degradation, wastes generate leachate and greenhouse gases (GHGs), which negatively impact water sources (leachate), soil, and human and animal health. This article describes the design of a two-phase biodigestion system for the degradation of organic matter and biogas production. The system uses citrus waste to produce biogas with neutral emissions. The biodigestion process begins with the stabilization of the methanogenesis reactor (UASB), which takes approximately 19 days. During this period, the biogas produced contains approximately 60% methane by volume. Subsequently, the packed bed reactor operates for 7 days, where hydrolytic and acetogenic bacteria decompose the citrus waste, leading to the production and accumulation of volatile fatty acids. The final step involves combining the two phases for 5 days, resulting in a daily biogas production ranging from 700 to 1100 mL. Of this biogas, 54.90% is methane ($\mathrm{C}{\mathrm{H}}_4$) with a yield of $0.51 \mathrm{L}\mathrm{C}{\mathrm{H}}_4{\left(\mathrm{g}\mathrm{S}\mathrm{V}\right)}^{-1}$. This study assesses the methane production capacity of citrus waste, with the process benefiting from the pH value of the leachate, enhancing its degradability. Consequently, this approach leads to a notable 27.30% reduction in solids within the digestion system. The two-phase anaerobic biodigestion system described in this article demonstrates a promising method to mitigate the environmental impact of citrus waste while concurrently producing a renewable source of energy.