Revista Internacional de Contaminación Ambiental
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Manifestaciones anómalas de mercurio atmosférico (GEM) y su relación con la actividad geotérmica de Pathé, estado de Hidalgo (México)
Get PDFThe Pathé geothermal zone (state of Hidalgo, Mexico) shows anomalous values of atmospheric mercury. The detected anomalies (Hg in air) coincide spatially with zones of advanced argillic alteration (former kaolin mines), which constitute natural sources of emissions of mercury, whose geological enrichment is due to water-rock interaction processes. Taking into account that the advanced argillic alteration indicates past steam-heated waters, it can be deduced that Hg was primarily mobilized as a gas, and it cannot be ruled out that it is still being emitted in the same way. However, from an environmental and health perspective, the maximum values of atmospheric Hg measured in the study area (36 ng/m3) are well below the threshold considered hazardous to human health. Nevertheless, it is advisable to carry out systematic monitoring of atmospheric Hg throughout the country —for environmental purposes—, in the potential sources of natural or anthropogenic emissions of this metal. According to our results, the proposed methodology could be an effective, simple, and rapid tool for geothermal and mining exploration since, through its application, certain areas of hydrothermal alteration (Hg-enriched) can be indirectly identified.La zona geotérmica de Pathé (Hidalgo, México) presenta valores anómalos de mercurio atmosférico. Las anomalías detectadas (Hg en el aire) coinciden espacialmente con zonas de alteración argílica avanzada (antiguas minas de caolín); éstas constituyen fuentes naturales de emisiones de dicho metal pesado, cuyo enriquecimiento geológico se debe a los procesos de interacción agua-roca. Al tomar en cuenta que esta alteración argílica avanzada indica antiguas zonas de condensación de vapor, se deduce que el Hg se movilizó principalmente como gas y no se puede descartar que actualmente se siga emitiendo de la misma manera. Ahora bien, desde una perspectiva ambiental y de salud, los valores máximos de Hg atmosférico medidos en la zona de estudio (36 ng/m3) quedan muy por debajo del umbral considerado peligroso para la salud humana. No obstante, es recomendable que se realicen monitoreos sistemáticos de Hg atmosférico en el país -con fines ambientales-, en las numerosas fuentes potenciales de emisiones naturales o antrópicas de dicho metal. De acuerdo con los resultados de este trabajo, la metodología que proponemos puede ser una herramienta efectiva, sencilla y rápida para la exploración geotérmica y minera, ya que, mediante su aplicación, es posible identificar de manera indirecta ciertas áreas de alteración hidrotermal que emiten Hg
Genotoxicity of the Herbicide Picloram (TORDON ® 24K) on tadpoles of Boana pulchella (Amphibia, Anura, Hylidae)
Get PDFPicloram (PIC) is an herbicide widely used in Uruguay to control weeds, especially in forest crops. In the present study, we evaluate the acute toxicity and genotoxicity of formulated 24.9% PIC-based Tordon®24K on Boana pulchella tadpoles under standard laboratory conditions. In the acute toxicity test we use mortality as the endpoint and we obtained a 48-h LC50 of 16.5 mg/L, LOEC 14.5 mg/L, and NOEC 12.5 mg/L. We determined genotoxicity in GS36 tadpoles exposed to sublethal concentrations of 8.5 (NOEC/1.5) and 12.5 mg/L (NOEC) PIC using micronucleus frequency (MN) and occurrence of nuclear abnormalities (AN) as endpoints. We noticed a significant increase in the frequency of MN and AN in all treatments tested at sublethal concentrations. Our findings demonstrate the genotoxic effects of this herbicide, which represent a danger to amphibians that inhabit agroecosystems. Based on the results obtained and considering that Boana pulchella is not a threatened species and has a wide distribution in the Uruguayan territory and the Pampa Biome, it could be considered a reference organism in environmental monitoring programs in the region.Picloram (PIC) is an herbicide widely used in Uruguay to control weeds, especially in forest crops. In the present study, we evaluate the acute toxicity and genotoxicity of formulated 24.9% PIC-based Tordon®24K on Boana pulchella tadpoles under standard laboratory conditions. In the acute toxicity test we use mortality as the endpoint and we obtained a 48-h LC50 of 16.5 mg/L, LOEC 14.5 mg/L, and NOEC 12.5 mg/L. We determined genotoxicity in GS36 tadpoles exposed to sublethal concentrations of 8.5 (NOEC/1.5) and 12.5 mg/L (NOEC) PIC using micronucleus frequency (MN) and occurrence of nuclear abnormalities (AN) as endpoints. We noticed a significant increase in the frequency of MN and AN in all treatments tested at sublethal concentrations. Our findings demonstrate the genotoxic effects of this herbicide, which represent a danger to amphibians that inhabit agroecosystems. Based on the results obtained and considering that Boana pulchella is not a threatened species and has a wide distribution in the Uruguayan territory and the Pampa Biome, it could be considered a reference organism in environmental monitoring programs in the region
Análisis de ciclo de vida de la remediación de suelo contaminado con plomo por lavado y fitoextracción
Get PDFMining wastes are disposed in tailings dams that contaminate soil. An agricultural soil in the municipality of Zimapán, Hidalgo, México, has been reported impacted by tailings, with a lead concentration of 647.5 mg Pb/kg of dry soil. This amount exceeded the maximum allowed limit (400 mg Pb/kg) established in the NOM-147-SEMARNAT/SS41-2004. For this reason, two technologies for its remediation have been evaluated in the laboratory: soil washing with ethyldiaminetetraacetic acid (EDTA) and assisted phytoextraction. In this paper, the evaluation of the impact of the life cycle of the two technologies was compared, one of them with two waste disposal scenarios, for which the functional unit was to remediate 1 kg of soil contaminated by mining tailings with 647.5 mg Pb/kg, to comply with the maximum allowed limit. The life cycle inventory was carried out for both technologies with experimental data and the Ecoinvent 3.8 database; and 18 catego-ries of impacts were calculated with the ReCiPe 2016 method and analyzed with the SimaPro v9.5 software. The contribution of EDTA soil washing is greater than that of assisted phytoextraction in 17 categories; the greatest contribution of assisted phytoex-traction was water consumption; and, for both technologies, the greatest contribution was carcinogenic human toxicity, due to the emission of toxic substances during the EDTA manufacturing process. Assisted phytoextraction was more viable than EDTA soil washing because it generates fewer environmental impacts.Los residuos de la minería se disponen en presas de jales que contaminan suelos. Se ha reportado un suelo agrícola del municipio de Zimapán, Hidalgo, México, impactado por jales, con una concentración de plomo de 647.5 mg Pb/kg de suelo seco, por arriba del límite máximo permisible (400 mg Pb/kg) establecido en la NOM-147-SEMARNAT/SS41-2004. Por ello, se han evaluado en laboratorio dos tecnologías para su remediación: lavado de suelo con ácido etildiaminotetraacético (EDTA) y fitoextracción asistida. En este trabajo se comparó la evaluación del impacto del ciclo de vida de las dos tecnologías, una de ellas con dos escenarios de disposición de residuos, para lo cual la unidad funcional fue remediar 1 kg de suelo contami-nado por jales mineros con 647.5 mg Pb/kg, para cumplir el límite máximo permisible. Se realizó para ambas tecnologías el inventario de ciclo de vida con datos experimentales y con la base de datos Ecoinvent 3.8; y se analizaron 18 categorías de impactos con el método ReCiPe 2016 mediante el software SimaPro v9.5. La contribución del lavado de suelos con EDTA es mayor que la de la fitoextracción asistida en 17 categorías; la mayor contribución de la fitoextracción asistida fue el consumo de agua; y, para ambas tecnologías, la mayor contribución fue la toxicidad humana carcinógena, debido a la emisión de sustancias tóxicas que ocurren durante el proceso de fabricación del EDTA. La fitoextracción asistida resultó ser más viable que el lavado con EDTA por generar menores impactos ambientales
Environmental impact assessment of biohydrogen production from orange peel waste by lab-scale dark and photofermentation processes
Get PDFOrange peel waste (OPW), as a relevant and recoverable residue, is composed of peel, internal tissue, pulp, and seeds. This organic residue is rich in carbohydrates useful for biofuel production processes. Biohydrogen is obtained from dark fermentation (DF) and photofermentation (PF), which are complementary in the bioprocessing chain. The objective of this work was to compare the environmental impact assessment of a sequential dark–photofermentation process (Scenario DF-PF) and the individual fermentation processes: dark fermentation (Scenario DF) and photofermentation (Scenario PF). The assessment was performed at a laboratory scale, and the functional unit (FU) was defined as the production of 1 kg H2. Scenario DF showed the lowest environmental impacts regarding global warming and fossil resource scarcity indicators, with 375.5 kg CO2-eq/FU and 108.8 kg oil-eq/FU, respectively, followed by Scenario DF-PF and Scenario PF. Scenario DF-PF presented the lowest impact regarding the water consumption indicator (7.6 m3/FU), followed by Scenario DF, which had 46.6% more impact. Additionally, Scenario DF-PF required 3.3 times less substrate than Scenario DF due to more efficient substrate conversion. The high share of fossil fuels in the Mexican electricity mix directly impacts the processes that require electric energy, such as the PF process. Therefore, eco-friendly light sources should be used to minimize effects. Valorization of OPW could follow two routes depending on whether the aim is to reduce a specific environmental impact indicator or biowaste conversion efficiency.Orange peel waste (OPW), as a relevant and recoverable residue, is composed of peel, internal tissue, pulp, and seeds. This organic residue is rich in carbohydrates useful for biofuel production processes. Biohydrogen is obtained from dark fermentation (DF) and photofermentation (PF), which are complementary in the bioprocessing chain. The objective of this work was to compare the environmental impact assessment of a sequential dark–photofermentation process (Scenario DF-PF) and the individual fermentation processes: dark fermentation (Scenario DF) and photofermentation (Scenario PF). The assessment was performed at a laboratory scale, and the functional unit (FU) was defined as the production of 1 kg H2. Scenario DF showed the lowest environmental impacts regarding global warming and fossil resource scarcity indicators, with 375.5 kg CO2-eq/FU and 108.8 kg oil-eq/FU, respectively, followed by Scenario DF-PF and Scenario PF. Scenario DF-PF presented the lowest impact regarding the water consumption indicator (7.6 m3/FU), followed by Scenario DF, which had 46.6% more impact. Additionally, Scenario DF-PF required 3.3 times less substrate than Scenario DF due to more efficient substrate conversion. The high share of fossil fuels in the Mexican electricity mix directly impacts the processes that require electric energy, such as the PF process. Therefore, eco-friendly light sources should be used to minimize effects. Valorization of OPW could follow two routes depending on whether the aim is to reduce a specific environmental impact indicator or biowaste conversion efficiency
Percepción acerca del manejo responsable de los aceites lubricantes usados: una aplicación de red semántica natural
Get PDFUsed lubricating oils (ULO) are waste that can cause damage to the environment when not correctly managed. In Mexico, one of the practices of lubricating oil consumers is to change vehicle´s motor oil at home. This used oil is usually disposed in sewers, vacant lots or burned without precautions, among other practices that negatively impact the environment. Therefore, it is important to study the generators using as a framework the theories that address environmental attitudes and apply this to the design of waste management strategies. This study investigates public perceptions of ULO disposal as household hazardous waste (HHW) and analyzes attitudes toward its responsible management in homes. By understanding these perspectives, we aim to develop strategies that align with public sentiment and require minimal municipal oversight. Our findings will enhance HHW management practices and reduce environmental impact. 100 vehicle owners from different social strata from Ensenada B.C. were surveyed. The results show that the lack of information about ULO management is the most common in men and women. It was also identified that there is a positive attitude towards responsible discharge and that this trend could be stabilized if dissemination and awareness campaigns are implemented.Los aceites lubricantes usados (ALU), pueden causar daños al ambiente cuando no son gestionados correctamente. En México, una de las prácticas de los consumidores de aceites lubricantes es realizar el cambio de aceite de sus vehículos en sus domicilios. El aceite usado resultante suele ser desechado en las coladeras, terrenos baldíos o quemado sin precauciones, entre otras prácticas que impactan negativamente el ambiente. Por ello es importante estudiar al generador tomando como marco las teorías que abordan las actitudes ambientales y aplicarlo al tema del manejo de residuos, en este caso de aceites usados. El objetivo de este estudio fue identificar los conceptos almacenados en la memoria semántica alrededor del desecho de los ALU como residuos peligrosos domésticos, en los individuos que los generan y manejan, con el fin de utilizarlos para el análisis de las actitudes hacia el manejo responsable de los ALU en los hogares, con la intención de diseñar estrategias alineadas con estas actitudes y que requieran supervisión mínima por parte de los municipios, quienes son los responsables de gestionarlos Para ello se utilizó el análisis de redes semánticas (ARS). Se encuestó a 100 propietarios de vehículos de distintos estratos sociales de la localidad de Ensenada, B.C. Los resultados muestran que la falta de información sobre el manejo de ALU es lo más común en hombres y mujeres. También se identificó que existe buena actitud hacia el desecho responsable y que esta tendencia podría mantenerse si se implementan campañas de difusión y concientización
The toxic legacy of artisanal and informal mining: XRF and gis analysis of soil contamination by Hg, Pb and As in the Secocha annex, Camaná, Peru
Get PDFHg, used as the main input in the gold amalgamation process in artisanal mining, along with lead Pb and As present in the toxic waste resulting from mining activity, cause serious effects on the environment and human health, as it occurs in the Secocha annex (Camaná, Peru). The objectives of the present study were to determine the concentrations of Hg, Pb, and As in the soil of the Secocha annex, evaluate the level of contamination of the site, determine the spatial distribution of contamination and the concentrations of the evaluated elements, and determine the origin of these contaminants. To achieve these objectives, satellite imagery, field sampling, X-ray fluorescence techniques, soil quality environmental regulations, geo-accumulation indices (Igeo), and geographic information system techniques were used. The results revealed maximum concentrations of 350 and 176.6 mg/kg for Hg and Pb, respectively. Of the 72 soil samples collected, the concentrations of Hg located within the urban/industrial area, where gold recovery activities are carried out, exceeded environmental regulations to a greater extent. In turn, the calculated Igeo revealed extreme soil contamination (5 < Igeo) due to the presence of Hg in most of the study area (95%), followed by moderate to heavy contamination (2 < Igeo < 3) due to the presence of Pb and As (0.5 and 5%, respectively). To reduce contamination and the concentrations of the evaluated elements, it is recommended to carry out studies to reuse inputs, change gold processing methodologies, and/or relocate the generated waste.Hg, used as the main input in the gold amalgamation process in artisanal mining, along with lead Pb and As present in the toxic waste resulting from mining activity, cause serious effects on the environment and human health, as it occurs in the Secocha annex (Camaná, Peru). The objectives of the present study were to determine the concentrations of Hg, Pb, and As in the soil of the Secocha annex, evaluate the level of contamination of the site, determine the spatial distribution of contamination and the concentrations of the evaluated elements, and determine the origin of these contaminants. To achieve these objectives, satellite imagery, field sampling, X-ray fluorescence techniques, soil quality environmental regulations, geo-accumulation indices (Igeo), and geographic information system techniques were used. The results revealed maximum concentrations of 350 and 176.6 mg/kg for Hg and Pb, respectively. Of the 72 soil samples collected, the concentrations of Hg located within the urban/industrial area, where gold recovery activities are carried out, exceeded environmental regulations to a greater extent. In turn, the calculated Igeo revealed extreme soil contamination (5 < Igeo) due to the presence of Hg in most of the study area (95%), followed by moderate to heavy contamination (2 < Igeo < 3) due to the presence of Pb and As (0.5 and 5%, respectively). To reduce contamination and the concentrations of the evaluated elements, it is recommended to carry out studies to reuse inputs, change gold processing methodologies, and/or relocate the generated waste
How healthy are horticultural plants cultivated in urban gardens in polluted cities? The case of Mexico City
Get PDFSoil-to-plant metal(loid) accumulation has been highly evaluated recently due to its significant impact on human health. This study reports the concentrations of 15 metal(oid)s in four vegetables (tomato, onion, chili, and lettuce) cultivated in a greenhouse and three shade houses (two roofs of buildings and one in the UNAM Botanical Garden) in four locations in the metropolitan area of Mexico City. In this experiment, the contribution of metals and metalloids due to atmospheric deposition and irrigation may be negligible. Hence, the concentration of metals depends only on transfer from the soil. Soil analysis indicates that only vanadium in one location (a rooftop garden in the municipality of Venustiano Carranza) exceeds the permissible limits according to Mexican regulations. Lettuce shows the highest concentrations and transfer factors for most metals compared to the other vegetables studied. Transfer factors were exceptionally high for Cd (lettuce) and Hg (tomato), presenting values above 1. Concentrations of As, Cd, Hg, and Pb were compared with limit values recommended by different international agencies for vegetables. It was observed that, except for As, these values are exceeded in various vegetables harvested in this study. This information must be corroborated with more detailed studies evaluating the chemical species in which those metal(oid)s are present and identify the physical and chemical parameters of the soil that may have interfered with the soil-plant transfer factor.Soil-to-plant metal(loid) accumulation has been highly evaluated recently due to its significant impact on human health. This study reports the concentrations of 15 metal(oid)s in four vegetables (tomato, onion, chili, and lettuce) cultivated in a greenhouse and three shade houses (two roofs of buildings and one in the UNAM Botanical Garden) in four locations in the metropolitan area of Mexico City. In this experiment, the contribution of metals and metalloids due to atmospheric deposition and irrigation may be negligible. Hence, the concentration of metals depends only on transfer from the soil. Soil analysis indicates that only vanadium in one location (a rooftop garden in the municipality of Venustiano Carranza) exceeds the permissible limits according to Mexican regulations. Lettuce shows the highest concentrations and transfer factors for most metals compared to the other vegetables studied. Transfer factors were exceptionally high for Cd (lettuce) and Hg (tomato), presenting values above 1. Concentrations of As, Cd, Hg, and Pb were compared with limit values recommended by different international agencies for vegetables. It was observed that, except for As, these values are exceeded in various vegetables harvested in this study. This information must be corroborated with more detailed studies evaluating the chemical species in which those metal(oid)s are present and identify the physical and chemical parameters of the soil that may have interfered with the soil-plant transfer factor
Producción de biocombustibles a partir de melaza de caña de azúcar usando Serratia marcescens
Get PDFIn this study, different concentrations of total sugars of sugarcane molasses of 0, 15, 30, 45, and 60 g/L were evaluated for the production of hydrogen, ethanol, and 3-methyl-1-butanol by Serratia marcescens (MZ413438) in dark fermentation. The maximum values of production were 3524.9 ± 5.1 mL/L for hydrogen, 2611.7 ± 71 mg/L for ethanol, and 136.9 ± 0.3 mg/L for 3-methyl-1-butanol obtained for 30 g/L concentrations. The data also show the susceptibility of Serratia marcescens (MZ413438) to concentrations of 60 g/L, obtaining hydrogen production values of 1249 ± 29.2 mL/L, ethanol of 1603.2 ± 79.3 mg/L, and 3-methyl-1-butanol of 100.4 ± 5.4 mg/L. The findings in this study increase the information on the production of biofuels within the framework of a biorefinery concept and offer alternative bioprocesses to be used for the generation of bioenergy from the treatment of agro-industrial waste.En este estudio, diferentes concentraciones de azúcares totales de melaza de caña de azúcar de 0, 15, 30, 45 y 60 g/L fueron evaluadas para la producción de hidrógeno, etanol y 3-metil-1-butanol mediante fermentación oscura de Serratia marcescens (MZ413438). Los máximos valores de producción fueron de 3524.9 ± 5.1 mL/L para hidrógeno, 2611.7 ± 71 mg/L para etanol y 136.9 ± 0.3 mg/L para 3-metil-1-butanol, obtenidos para una concentración de 30 g/L. Los datos también nos muestran la sensibilidad de Serratia marcescens (MZ413438) a concentraciones de 60 g/L, obteniéndose valores de producción para hidrógeno de 1249 ± 29.2 mL/L, para etanol de 1603.2 ± 79.3 mg/L y para 3-metil-1-butanol de 100.4 ± 5.4 mg/L. Los hallazgos de este estudio incrementan la información sobre la producción de biocombustibles en el marco de un concepto de biorrefinería, y ofrecen bioprocesos alternativos para ser la generación de bioenergía a partir del tratamiento de residuos agroindustriales
Influencia de las variaciones climáticas en las infecciones parasitarias de la sierra Scomberomorus sierra (Jordan et Starks) en la Bahía de Acapulco, Guerrero, México
Get PDFThere are few studies focused on determining the possible effects of natural oceanographic phenomena such as El Niño-Southern Oscillation (ENSO) on the structuring of marine parasite communities. A total of 391 Scomberomorus sierra specimens were examined for parasites over a 9-year period (March 2011 to May 2019) in Acapulco Bay, Guerrero, Mexico. This study aimed to examine the effects of anomalous climatic events such as La Niña and El Niño on the parasite communities of this marine fish. Twenty species of metazoan parasites (15 helminths and five crustaceans) were identified during the present study. The parasite communities were characterized by a high dominance of ectoparasites, representing 80 % of the total number of collected parasites. Important changes in the structure and species composition of the parasite communities were recorded during the cold and warm phases of ENSO. Intestinal parasite infections were more frequent during the cold phase, while copepod ectoparasite infections were more frequent and intense during the warm weather. Variations in the infection levels of some species of ecto and endoparasites generated important changes in the parasite community structure of S. sierra in Acapulco Bay during these atypical climatic events.Los parásitos son considerados como componentes invisibles de los ecosistemas acuáticos y terrestres, los cuales tienen una gran importancia en la dinámica y el flujo de energía dentro de las redes tróficas. Existen pocos estudios enfocados a determinar los posibles efectos que pueden tener algunos fenómenos naturales oceanográficos, tales como El Niño-Oscilación del Sur (ENOS), sobre la estructuración de las comunidades de parásitos de peces marinos. Durante un periodo de nueve años (marzo 2011 a mayo 2019) se examinaron un total de 391 ejemplares de Scomberomorus sierra en la bahía de Acapulco, Guerrero. El objetivo del estudio fue examinar los efectos de eventos climáticos anómalos como La Niña y El Niño sobre las comunidades de parásitos de este pez marino. En el presente estudio se identificaron un total de 20 especies de parásitos metazoarios (15 helmintos y cinco crustáceos). Las comunidades se caracterizaron por una alta dominancia de ectoparásitos, los cuales representaron el 80 % del total de parásitos recolectados. Se registraron cambios importantes en la estructura y composición de especies de las comunidades de parásitos durante las fases fría y cálida del ENOS. Infecciones de algunos parásitos intestinales fueron más frecuentes durante la fase fría, en tanto que durante la cálida fueron más frecuentes e intensas las infecciones por copépodos ectoparásitos. Las variaciones en los niveles de infección de algunas especies de ecto y endoparásitos generaron cambios importantes en la estructura de las comunidades de parásitos de S. sierra en la bahía de Acapulco, durante la ocurrencia de estos eventos climáticos atípicos
Obtención de antioxidantes y producción de biometano a partir de variedades de Opuntia
Get PDFEn este trabajo, se investigaron variedades de Opuntia para comprobar su potencial para encajar en un enfoque de biorrefinería. Para ello, se propuso la extracción de antioxidantes y la producción de biometano a partir de sus efluentes sólidos. Tres variedades de Opuntia –O. ficus-indica var. Milpa Alta (OfiM), O. ficus-indica var. Copena (OfiC) y O. engelma-nii (Oe)– se sometieron a extracción con disolventes. Se encontró que el metanol al 80 %produjo la mayor cantidad de compuestos fenólicos (8.99 mg/g) y flavonoides (1.67 mg/g) en OfiM. Posteriormente, en los experimentos de potencial de biometano se compararon biomasas crudas y residuales, así como la relación inóculo-sustrato (ISR, 0.5, 1.5 y 2.5). Los rendimientos de biometano fueron menores con biomasa residual que con Opuntia cruda. El mayor rendimiento de biometano de 552 mL CH4/g SV se alcanzó con OfiM cruda y ISR 2.5. En el segundo ensayo de OfiM, los rendimientos de biometano fueron de 412 y 458 mL CH4/g SV para biomasas residuales y crudas, respectivamente. A pesar de una disminución de aproximadamente 10 % en el rendimiento de biometano debido al proceso de extracción de fenólicos, el acoplamiento de ambos procesos resulta conveniente para la obtención compuestos extraíbles de alto valor y una producción sustancial de biometano, lo que representa un paso hacia la biorrefinería de Opuntia.
The experiment initially focused on evaluating the antioxidant extraction capabilities of methanol and ethanol solvents at different concentrations (80% and 100%) on three Opuntia varieties: O. ficus-indica var. Milpa Alta (OfiM), O. ficus-indica var. Copena (OfiC), and O. engelmannii (Oe). Subsequently, the biomethane potential experiments were carried out to compare the raw and residual biomasses. The main variable considered during anaerobic digestion was the inoculum to substrate ratio (ISR, 0.5, 1.5 and 2.5).
The highest amounts of phenolic compounds (8.99 mg/g) and flavonoids (1.67 mg/g) were extracted from OfiM using 80% methanol. Interestingly, methane yields were generally lower when using residual biomass than with raw Opuntia. For OfiM, the biomethane yields were 411.8 mL CH4/g VS and 458.6 mL CH4/g VS, respectively, for residual and raw biomasses. The highest biomethane yield 552 mL CH4/g VS was obtained with raw OfiM at ISR 2.
Despite a decrease of approximately 10% in biomethane yield after the antioxidant extraction stage, this work highlights that Opuntia aligns with the biorefinery paradigm, owing to its easily extractable compounds and the substantial biomethane potential.El género Opuntia comprende plantas crasuláceas adaptables a diversos entornos, incluidas las regiones áridas. Estas plantas son conocidas por su alto contenido en fibra y sus propiedades antioxidantes. Su biomasa puede procesarse para extraer compuestos como antioxidantes (compuestos fenólicos, flavonoides, antocianinas y otros pigmentos), pectina y mucílagos; y para producir biocombustibles como bioetanol y biogás. En este trabajo se evaluó el procesado secuencial de Opuntia, la extracción de antioxidantes y la producción de biometano a partir de la biomasa residual.
El experimento se centró inicialmente en evaluar la capacidad de extracción de antioxidantes de los disolventes metanol y etanol a diferentes concentraciones (80% y 100%) en tres variedades de Opuntia: O. ficus-indica var. Milpa Alta (OfiM), O. ficus-indica var. Copena (OfiC), y O. engelmannii (Oe). Posteriormente, se llevaron a cabo los experimentos de potencial de biometano para comparar las biomasas crudas y residuales. La principal variable considerada durante la digestión anaerobia fue la relación inóculo/sustrato (RIS: 0.5, 1.5 y 2.5).
Los mejores rendimientos de compuestos fenólicos (8.99 mg/g) y flavonoides (1.67 mg/g) se extrajeron de OfiM utilizando metanol al 80%. Adicional, los rendimientos de metano fueron generalmente más bajos cuando se utilizó biomasa residual que con Opuntia cruda. Para OfiM, los rendimientos de biometano fueron de 411.8 mL CH4/g SV y 458.6 mL CH4/g SV, para biomasas residuales y crudas, respectivamente. El mayor rendimiento de biometano, 552 mL CH4/g SV, se obtuvo con OfiM cruda en RIS 2.
A pesar de una disminución de aproximadamente el 10% en el rendimiento de biometano durante la etapa de extracción de antioxidantes, este trabajo destaca que Opuntia se alinea con el paradigma de la biorrefinería, debido a sus compuestos fácilmente extraíbles y el considerable potencial de biometano