Revista Internacional de Contaminación Ambiental
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USO DE BACTERIAS ÁCIDO LÁCTICAS PARA DESCONTAMINACIÓN DE ESTIÉRCOL PORCINO MEDIANTE ENSILAJE EXPERIMENTAL
Get PDFSwine production generates every day a large amount of residues, including nutrients and microorganisms, which potentially contribute to contamination of air, water and soil, and generation of unpleasant odors. Many strategies have been developed in order to mitigate the contaminant effect of swine manure and to take advantage of its nutrients and beneficial compounds; silage is an example of these, and consists in swine manure fermentation mainly under anaerobic conditions. The aim of this study was to assess the effect of applying a process of silage to swine manure added with two different sources of carbohydrates and two different sources of lactic-acid bacteria, under the reduction of different microbiological indicators. Through the process, it was observed the reduction of pH levels (until reaching 4.6) and microbial content, mainly for coliforms (reduction greater than 5 log), molds and yeasts, and total elimination of enterococci. On the other hand, significant decline was not reported for the lactic-acid bacteria content, main responsible of fermentation process. Best results were observed through using sorghum as a source of carbohydrates and cheese whey as a source of lactic-acid bacteria, for both, decrease of pH and reduction of some microbiological indicators, including bacteria that produce sulfuric acid. Therefore, silage process, applied to swine manure, induces the decrease of pH for action of lactic-acid bacteria until limit the survival of bacteria associated with fecal contamination, making of swine a transformed and microbiologically safe residue for its handling and subsequent use. La actividad porcina genera diariamente una gran cantidad de residuos conformados por nutrientes y microorganismos que potencialmente contribuyen a la contaminación de agua, aire y suelos, y la subsecuente generación de olores desagradables. Diversas estrategias se han desarrollado para mitigar el efecto contaminante de las excretas porcinas y aprovechar sus nutrientes; tal es el caso del ensilaje, que consiste en la fermentación de las excretas. En este estudio se evaluó el efecto del ensilaje del estiércol porcino adicionado con dos fuentes diferentes de carbohidratos y dos fuentes de bacterias ácido lácticas, sobre la reducción de diferentes grupos de microorganismos. Durante el proceso se observó la disminución del pH (hasta 4.6) y la carga microbiana, sobre todo para organismos coliformes (reducción mayor a 5 logaritmos) y hongos y levaduras, así como la eliminación total del grupo de enterococos; mientras que el contenido de bacterias ácido lácticas, principales responsables de la fermentación, permaneció constante. Los mejores resultados se observaron mediante el uso de sorgo como fuente de carbohidratos en combinación con suero de leche, subproducto de la elaboración de queso, como fuente de bacterias ácido lácticas, tanto en disminución del pH como en la reducción de algunos indicadores microbiológicos, incluidas las bacterias productoras de ácido sulfhídrico. Mediante el ensilaje del estiércol porcino se favorece la disminución del pH por acción de las bacterias ácido lácticas a niveles que limitan la sobrevivencia de microorganismos asociados a contaminación fecal, y lo transforman en un producto seguro, desde la perspectiva microbiológica, para su manejo y posible aprovechamiento subsecuente.
EVALUACIÓN DE LA TOXICIDAD DEL CLORPIRIFÓS EN ALEVINOS DE CACHAMA BLANCA (Piaractus brachypomus)
Get PDFPesticides have become an important environmental problem due to their indiscriminate and lack of control use, which ends up affecting drastically non-target organisms, including aquatic species. The acute and chronic toxicity of chlorpyrifos was determined in fingerlings of red-bellied pacu (Piaractus brachypomus), and it was established the value of the median lethal concentration (LC50) at 96 h, which was evaluated in 88 fish exposed to chlorpyrifos concentrations from 0.015 to 1.5 μg/L. The value established for CL50 was 0.11 μg/L (p < 0.05). The chronic toxicity test to sublethal doses (0.5, 0.1 and 0.001 x of the LC50 dose) was performed in 60 animals per treatment plus a witness group. Animals were exposed for 50 days, followed by 50 days without exposure, to evaluate both respiratory burst activity and plasma bactericidal activity in a challenge with Aeromonas hydrophila. Lower levels of respiratory burst were found in the exposed group to 0.0011 μg/L in 20 and 50 days, which increased in the exposed group to 0.055 μg/L at day 90. In addition, the bactericidal activity of plasma showed a decrease until day 40 in exposed animals compared to the witness. Also, in a trial of subchronic exposure without recovery to sublethal doses of chlorpyrifos (0.011 μg/L), lesions were found in gills, liver, kidney and brain. This study has demonstrated the high sensitivity of this species to chlorpyrifos, postulating P. brachypomus as a bioindicator of water pollution.Los pesticidas se han convertido en un importante problema ambiental, debido a su utilización indiscriminada y al poco control en su uso, lo que termina afectando drásticamente a organismos no blanco de su acción, incluyendo especies acuáticas. Se determinó la toxicidad aguda y crónica del clorpirifós en alevinos de cachama blanca (Piaractus brachypomus) y se estableció el valor de la concentración letal 50 (CL50) a 96 horas, el cual fue evaluado en 88 peces expuestos a concentraciones de clorpirifós de 0,015 a 1,5 µg/L. El valor establecido para la CL50 fue de 0,11 µg/L (p<0,05).El ensayo de toxicidad crónica a dosis subletales (0,5x, 0,1x y 0,001x de la CL50), se realizó en 60 animales por tratamiento más un grupo control negativo, expuestos por 50 días, seguido de 50 días sin exposición, evaluando la actividad de explosión respiratoria y la capacidad bactericida del plasma en un desafío a Aeromonas hydrophila. Se encontraron niveles menores de explosión en el grupo expuesto a 0,0011 µg/L en los días 20 y 50 y un incremento en el grupo expuesto a 0,055 µg/L al día 90; además, la actividad bactericida del plasma mostró una disminución hasta el día 40 en los animales expuestos comparados con el grupo control. Adicionalmente, en un ensayo de exposición subcrónica sin recuperación a dosis subletal de clorpirifós (0,011 µg/L), se hallaron lesiones en branquias, hígado, riñón y encéfalo. Este estudio ha demostrado la alta sensibilidad de la especie al clorpirifós postulándose a P. brachypomus como bioindicador de contaminación hídrica
CAMBIOS EN LA ACTIVIDAD DE ENZIMAS ANTIOXIDANTES DE Myriophyllum quitense EXPUESTA A ENDOSULFÁN A DIFERENTES TEMPERATURAS.
Get PDFAquatic macrophytes have been widely used as environmental biomonitors because of their primary role in ecosystems and because water bodies are the final destination of many xenobiotics. Particularly, several biomarkers have been used in the genus Myriophyllum for toxicity tests. However, there is scarce evidence of the potential effect of the “confounding factors” on these biomarkers. The objective of the present work was to evaluate the possible effect of temperature on the activity of antioxidant enzymes in Myriophyllum quitense exposed to environmentally relevant concentrations of the insecticide endosulfan. The activity of the enzymes catalase (CAT) and guaiacol peroxidase (POD), as well as glutathione-s-transferase in the cytosolic (GSTc) and microsomal (GSTm) fractions, were evaluated in plants exposed to two temperatures: 11 and 19 ºC, and two concentrations of endosulfan (ES): 5 and 10 μg/L. Interaction between temperature and ES concentration for CAT and POD activities was observed. Differences in the activities of all enzymes were detected when plants were exposed to 11 ºC with respect to controls. However, no significant differences were observed in the enzymatic activities of the plants exposed to ES at 19 ºC. These results emphasize the importance of considering the evaluation of factors such as temperature in bioassays, since its effect alters the toxicity of the contaminant.Las macrófitas acuáticas han sido ampliamente utilizadas como biomonitores ambientales por su rol primordial en el ecosistema y porque los cuerpos de agua son el destino final de muchos xenobióticos. En particular, se han utilizado varios biomarcadores del género Myriophyllum para evaluaciones de toxicidad; sin embargo, existen pocos antecedentes sobre el efecto potencial de los “factores de confusión” sobre dichos biomarcadores. El objetivo del presente trabajo fue evaluar el efecto de la temperatura en la actividad de enzimas antioxidantes en Myriophyllum quitense expuesta a concentraciones de relevancia ambiental del plaguicida endosulfán (ES). Se evaluó la actividad de las enzimas catalasa (CAT) y guayacol peroxidasa (POD), así como glutatión-S-transferasa en su fracción citosólica (GSTc) y microsomal (GSTm), en plantas expuestas a dos temperaturas (11 y 19 ºC) y a dos concentraciones de ES: 5 y 10 µg/L. Se observó interacción entre la temperatura y la concentración de ES para las actividades de CAT y POD, y diferencias en las actividades de las cuatro enzimas cuando las plantas fueron expuestas a 11 ºC, respecto de los controles. Sin embargo, no se observaron diferencias significativas en las actividades enzimáticas de las plantas expuestas a ES a 19 ºC. Estos resultados indican la importancia de considerar la evaluación de factores como la temperatura en bioensayos, dado que su efecto altera la toxicidad del contaminante
AZOXYSTROBIN INDUCES CHROMOSOMAL ABERRATIONS IN ROOTS OF THE HYDROPHYTE Bidens laevis L.
Get PDFAquatic plants can be used as in situ bioindicators of water quality due to their ability to accumulate agrochemicals. However, these plants may be at significant ecotoxicological risk from pesticides applied in crop fields. The fungicide azoxystrobin (AZX) induces DNA damage and changes in the antioxidant enzymatic system in leaves of the submerged hydrophyte Myriophyllum quitense. In the present study, the objectives were to determine whether AZX induces chromosomal damage in roots of the wetland plant Bidens laevis and to evaluate whether the damage in the antioxidant system was associated with damage in the photosynthetic system. Two experiments were carried out to evaluate the short-term effects (1 or 2 days) of the exposure to different concentrations of the active ingredient of AZX (0, 0.1, 1, 10, 50, 100 µg/L) on intact B. laevis plants. In the first experiment, photosynthetic biomarkers, including chlorophyll a fluorescence, SPAD units, and chlorophyll a and b content, were measured. In the second experiment, the frequency of chromosome aberrations (CA) was evaluated in root tips. In general, the photosynthetic biomarkers evaluated were not affected by AZX, except for a decrease in chlorophyll b content at 100 µg/L. Total CA increased at all AZX concentrations and the most frequent abnormalities were laggards and chromosomes not congregated at the metaphase equator, both indicators of spindle disturbance. This is the first report of AZX-induced chromosomal aberrations in a wetland plant exposed to environmentally relevant concentrations of the fungicide. The reason why AZX exposure had only a limited impact on biomarkers of the photosynthetic apparatus is discussed.Aquatic plants can be used as in situ bioindicators of water quality due to their ability to accumulate agrochemicals. However, these plants may be at significant ecotoxicological risk from pesticides applied in crop fields. The fungicide azoxystrobin (AZX) induces DNA damage and changes in the antioxidant enzymatic system in leaves of the submerged hydrophyte Myriophyllum quitense. In the present study, the objectives were to determine whether AZX induces chromosomal damage in roots of the wetland plant Bidens laevis and to evaluate whether the damage in the antioxidant system was associated with damage in the photosynthetic system. Two experiments were carried out to evaluate the short-term effects (1 or 2 days) of the exposure to different concentrations of the active ingredient of AZX (0, 0.1, 1, 10, 50, 100 µg/L) on intact B. laevis plants. In the first experiment, photosynthetic biomarkers, including chlorophyll a fluorescence, SPAD units, and chlorophyll a and b content, were measured. In the second experiment, the frequency of chromosome aberrations (CA) was evaluated in root tips. In general, the photosynthetic biomarkers evaluated were not affected by AZX, except for a decrease in chlorophyll b content at 100 µg/L. Total CA increased at all AZX concentrations and the most frequent abnormalities were laggards and chromosomes not congregated at the metaphase equator, both indicators of spindle disturbance. This is the first report of AZX-induced chromosomal aberrations in a wetland plant exposed to environmentally relevant concentrations of the fungicide. The reason why AZX exposure had only a limited impact on biomarkers of the photosynthetic apparatus is discussed
REMOCIÓN DE COLORANTES AZO CON ALGINATO: RELACIÓN ENTRE ESTRUCTURA DE COLORANTE Y EFICIENCIA DE REMOCIÓN
Get PDFThe azo dyes represent between 60-75 % of the total of dyes produced nowadays. They are widely used in cosmetic industry, paper, optoelectronic, textile, etc. Unfortunately, due to their high resistance to the conventional treatments applied to wastewaters, they pollute the water bodies where are discharged. In this report, the sodium alginate (ALG) is evaluated for the removal of the azo dyes, Direct red 80 (DR80), Congo red (Rcongo) and Methyl red (Rmetilo). UV-visible, FTIR and Raman spectroscopic studies helped to elucidate the formation of tautomers, species responsible for their removal. The removal percentages were: DR80 (99.9 % at pH = 12 and ionic strength = 0.1 M), Rcongo (99.7 % at pH = 12 and ionic strength = 0.1 M), and Rmetilo (14.9 % at pH = 7 and ionic strength = 0.1 M). The Zimm-Bragg model described adequately the experimental isotherms, suggesting the importance of dye´s aggregation in their removal efficiency. Additionally, the removal efficiency of seven azo dyes was compared and it was found that the highest removal efficiencies are achieved when dye molecules exhibit high molecular weight, planarity and are positively charged. This allows us to predict in a qualitative way, from the azo dye structures, which of them will be removed more efficiently with ALG. Los colorantes azo representan entre 60 y 75 % de los colorantes producidos actualmente. Se utilizan ampliamente en la industria cosmética, del papel, optoelectrónica, textil, etc. Desafortunadamente una vez utilizados, debido a su alta resistencia a tratamientos convencionales de aguas residuales, contaminan los cuerpos de agua donde son descargados. En este reporte se utiliza alginato de sodio (ALG) para remover los colorantes azo rojo directo 80 (RD80), rojo congo (Rcongo) y rojo de metilo (Rmetilo). Estudios de espectroscopía UV-visible, FTIR y Raman ayudaron a elucidar los tautómeros involucrados en su remoción. Los porcentajes de remoción fueron: RD80 (99.9 % a pH = 12 y fuerza iónica= 0.1 M), Rcongo (99.7 % a pH = 12 y fuerza iónica = 0.1 M) y Rmetilo (14.9 % a pH = 7 y fuerza iónica = 0.1 M). El modelo de Zimm-Bragg describe adecuadamente las isotermas experimentales, sugiriendo la importancia de la agregación de los colorantes en su eficiencia de remoción. Adicionalmente, se comparó la eficiencia de remoción de siete colorantes azo y se encontró que moléculas con peso molecular elevado, con alta planaridad y carga positiva mostraron las mayores eficiencias de remoción. Lo anterior permite predecir cualitativamente a partir de las estructuras de colorantes azo, cuál de ellos será removido más eficientemente con el ALG
TRATAMIENTO DE UN AGUA RESIDUAL INDUSTRIAL A TEMPERATURA PSICROFÍLICA CON UN REACTOR UASB
Get PDFIn the present work, a laboratory scale anaerobic upflow reactor (UASB) was operated with a hydraulic retention time (6 h) and at psychrophilic temperature (< 20 ºC). The UASB reactor treated wastewater from a chocolate industry with two applied organic volumetric loads (OLRapl). Each OLRapl corresponded to an experimental stage: experimental stage I with 1.8 ± 0.8 kg soluble oxygen chemical demand ([DQOs]/m3/d) and experimental stage II with 3.5 ± 0.9 kg CODs/m3/d. The objective of this research was to evaluate the removal efficiency of CODs (RE), biogas production (BP) and experimental cell yield (Yexp) within the laboratory scale UASB reactor. The control parameters monitored were pH, temperature and flow. Alkalinity, volatile fatty acids and CODs were analyzed in the influent and effluent, while suspended solids were analyzed inside the reactor and in the effluent. The RE during the steady state of the two experimental stages was greater than 90 %. The high RE obtained showed that the UASB reactor efficiently treated the industrial wastewater at low temperature with the OLRapl. BP increased when OLRapl increased (1.6 ± 0.8 and 3.5 ± 1.3 L/d of OLRapl of 1.8 and 3.5 kg CODs/m3/d, respectively [1 atm, 273 K]). The Yexp of experimental stage II was high (0.11 kg SSV/kg CODrem). The high Yexp of experimental stage II could be due to the influence of psychrophilic temperature in the growth rate of anaerobic microorganisms.En el presente trabajo se operó un reactor anaerobio de flujo ascendente (UASB, por sus siglas en inglés) a escala de laboratorio con un tiempo de retención hidráulico (6 h) y a temperatura psicrofílica (< 20 ºC). En el reactor UASB se trató agua residual de una industria chocolatera con dos cargas orgánicas volumétricas aplicadas (COVapl). Cada COVapl correspondió a una etapa experimental: la etapa experimental I con 1.8 ± 0.8 kg de demanda química de oxígeno soluble ([DQOs]/m3/d) y la etapa experimental II con 3.5 ± 0.9 kg DQOs/m3/d. El objetivo fue evaluar la eficiencia de remoción de la DQOs (ER), la producción de biogás (PB) y el rendimiento celular experimental (Yexp) en un reactor UASB a escala de laboratorio. Los parámetros de control monitoreados fueron pH, temperatura y flujo. La alcalinidad, ácidos grasos volátiles y DQOs se analizaron en el influente y efluente, mientras que los sólidos suspendidos se analizaron dentro del reactor y en el efluente. Durante el estado estacionario de las dos etapas experimentales la ER fue mayor al 90 %. La elevada ER obtenida mostró que en el reactor UASB se trató eficientemente el agua residual industrial a baja temperatura con las COVapl. La PB se incrementó cuando la COVapl aumentó (1.6 ± 0.8 y 3.5 ± 1.3 L/d con la COVapl de 1.8 y 3.5 kg DQOs/m3/d, respetivamente [1 atm, 273º K]). El Yexp de la etapa experimental II fue alto (0.11 kg SSV/kg DQOrem), lo cual pudo deberse a que la temperatura psicrofílica influyó sobre la tasa de crecimiento de los microorganismos anaerobios
KITCHEN WASTE SOLID STATE FERMENTATION BY Aspergillus niger TO PRODUCE ACID PROTEASE
Get PDFAcid protease production was carried out by solid state fermentation (SSF) with Aspergillus niger using kitchen waste as the principal raw material. The SSF conditions were studied and the optimal one was identified. This study explored effects of different water contents in SSF medium, different inoculum sizes and different fermentation time on acid protease activities by following the one-factor-at-a-time method. Based on the results obtained, the optimal fermentation conditions for the production of c acid protease, were are as follows: 30g of kitchen waste content, 20mL of initial water content, 4mL of inoculum, and 70h ofas fermentation time. Under these fermentation conditions, the activity of the acid protease was 223.518 U.Acid protease production was carried out by solid state fermentation (SSF) with Aspergillus niger using kitchen waste as the principal raw material. The SSF conditions were studied and the optimal one was identified. This study explored effects of different water contents in SSF medium, different inoculum sizes and different fermentation time on acid protease activities by following the one-factor-at-a-time method. Based on the results obtained, the optimal fermentation conditions for the production of c acid protease, were are as follows: 30g of kitchen waste content, 20mL of initial water content, 4mL of inoculum, and 70h ofas fermentation time. Under these fermentation conditions, the activity of the acid protease was 223.518 U
HEAVY METAL REMOVAL FROM DREDGING SLURRY USING A PARABOLIC HYDROCYCLONE
Get PDFHeavy metals usually aggregate as fine particles in dredging slurry and need to be removed or reduced before recycling of the slurry. However, traditional hydrocyclone method often leads to low separation efficiency because of the difficulties in the complete separation of fine particles. To address this problem, this paper proposes a new type of parabolic hydrocyclone for the removal of heavy metals from dredging slurry. The computational fluid dynamics (CFD) software together with mixture and Reynolds stress model (RSM) have been used to simulate the internal flow field of the parabolic hydrocyclone, which was then verified with experimental tests. The simulation results show that, compared with traditional hydrocyclones, the flow field inside the parabolic hydrocyclone is more stable, which effectively help to avoid the mixture of coarse and fine particles caused by the flow field disturbance. Further experimental results demonstrate that the cumulative percentage of fine particles in the underflow product decreases. The cut size increases from 30 μm to 49 μm and the steepness index rises from 0.13 to 0.2, which proves that the separation accuracy can be improved, and the fine particles mixed in the underflow can be removed effectively. Moreover, the recovery rate of heavy metalas Zn and Cr in the overflow products reaches 97.21 % and 78.27 %, respectively, verifying the enrichment effect. Therefore, after the parabolic hydrocyclone separation process, the underflow products contain less heavy metals and become both non-hazardous and recyclable. Heavy metals usually aggregate as fine particles in dredging slurry and need to be removed or reduced before recycling of the slurry. However, traditional hydrocyclone method often leads to low separation efficiency because of the difficulties in the complete separation of fine particles. To address this problem, this paper proposes a new type of parabolic hydrocyclone for the removal of heavy metals from dredging slurry. The computational fluid dynamics (CFD) software together with mixture and Reynolds stress model (RSM) have been used to simulate the internal flow field of the parabolic hydrocyclone, which was then verified with experimental tests. The simulation results show that, compared with traditional hydrocyclones, the flow field inside the parabolic hydrocyclone is more stable, which effectively help to avoid the mixture of coarse and fine particles caused by the flow field disturbance. Further experimental results demonstrate that the cumulative percentage of fine particles in the underflow product decreases. The cut size increases from 30 μm to 49 μm and the steepness index rises from 0.13 to 0.2, which proves that the separation accuracy can be improved, and the fine particles mixed in the underflow can be removed effectively. Moreover, the recovery rate of heavy metalas Zn and Cr in the overflow products reaches 97.21 % and 78.27 %, respectively, verifying the enrichment effect. Therefore, after the parabolic hydrocyclone separation process, the underflow products contain less heavy metals and become both non-hazardous and recyclable.
SINGLE TREE THREE-DIMENSIONAL MODEL CONSTRUCTION AND IMPACT FACTOR EXTRACTION BASED ON OBLIQUE PHOTOGRAMMETRY
Get PDFBased on the digital photogrammetry principle and the computer vision theory, this paper utilizes Unmanned Aerial Vehicle (UAV) oblique photogrammetry technology to construct vegetation canopy structure three-dimensional model and to extract three-dimensional model impact factor by conducting image data orientation, matching and aerial triangulation. In order to verify whether the extraction factor is correct, this paper adopts vegetation point cloud data which are obtained from three-dimensional laser scanning. Combined with the actual case analysis, the results of the analysis show that the factor data extracted from the model are reliable.Based on the digital photogrammetry principle and the computer vision theory, this paper utilizes Unmanned Aerial Vehicle (UAV) oblique photogrammetry technology to construct vegetation canopy structure three-dimensional model and to extract three-dimensional model impact factor by conducting image data orientation, matching and aerial triangulation. In order to verify whether the extraction factor is correct, this paper adopts vegetation point cloud data which are obtained from three-dimensional laser scanning. Combined with the actual case analysis, the results of the analysis show that the factor data extracted from the model are reliable
DYNAMIC REGULATION OF NATURAL SCENIC AREA SYSTEM FROM THE PERSPECTIVE OF ECOLOGICAL CIVILIZATION
Get PDFEcological civilization is an organic unity of theory and practice. The ecological civilization of natural scenic areas has received extensive attention from scholars at home and abroad in recent years. This paper explores the connotation of ecological civilization of natural scenic area system and constructs a natural scenic area system model based on system dynamics. In addition, this paper takes Jiuzhai Valley as research object to regulate and analyze the key factors that may affect ecological civilization construction in scenic areas, explores scenic area development trend under different strategies, and provides a basis for the promotion of ecological civilization construction in natural scenic areas.Ecological civilization is an organic unity of theory and practice. The ecological civilization of natural scenic areas has received extensive attention from scholars at home and abroad in recent years. This paper explores the connotation of ecological civilization of natural scenic area system and constructs a natural scenic area system model based on system dynamics. In addition, this paper takes Jiuzhai Valley as research object to regulate and analyze the key factors that may affect ecological civilization construction in scenic areas, explores scenic area development trend under different strategies, and provides a basis for the promotion of ecological civilization construction in natural scenic areas