Biofiltración de compuestos orgánicos volátiles utilizando diferentes tipos de lecho basados en mezclas de compost de RSU-poda: monitorización mediante diversas técnicas

Tesis descargada en TeseoComposting is one of the most successful biological processes for the treatment of the residues enriched in putrescible materials. The optimization of parameters which have an influence on the stability of the products is necessary in order to maximize recycling and recovery of waste components. The influence of the composting process parameters (aeration, moisture, C/N ratio, and time) on the stability parameters (organic matter, N-losses, chemical oxygen demand, nitrate, biodegradability coefficient) of the compost was studied. The composting experience was carried out using Municipal Solid Waste (MSW) and Legume Trimming Residues (LTR) in 200 L isolated acrylic barrels following a Box-Behnken central composite experimental design. Second-order polynomial models were found for each of the studied compost stability parameter, which accurately described the relationship between the parameters. The differences among the experimental values and those estimated by using the equations never exceeded 10% of the former. Results of the modelling showed that excluding the time, the C/N ratio is the strongest variable influencing almost all the stability parameters studied in this case, with the exception of N-losses which is strongly dependent on moisture. Moreover, an optimized ratio MSW/LTR of 1/1 (w/w), moisture content in the range of 40-55% and moderate to low aeration rate (0.05-0.175 Lair kg-1 min-1) is recommended to maximise degradation and to obtain a stable product during co-composting of MSW and LTR. On the other hand, the concentration of volatile organic compounds (VOCs) during the composting of kitchen waste and pruning residues in a pilot plant, and the abatement of VOCs by different compost biofilters was studied. VOCs removal efficiencies greater than 90% were obtained using composts of municipal solid waste (MSW) or MSW-pruning residue as biofilter material. An electronic nose identified qualitative differences among the biofilter output gases at very low concentrations of VOCs. These differences were related to compost constituents, compost particle size (2-7 or 7-20 mm), and a combination of both factors. The total concentration of VOCs determined by a photoionization analyser and inferred from electronic nose data sets were correlated over an ample range of concentrations of VOCs, showing that these techniques could be specially adapted for the monitoring of these processes. Finally, a biofiltration system was designed using mature composts of municipal solid waste (MSW) or MSW mixed with pruning residues (MSW-P) as packing materials to treat vapours of ¿-pinene (a dominant volatile organic compounds (VOC) emitted during the MSW- P co-composting) and Methyl ethyl ketone (MEK). Monitoring the efficiency of the biofiltration system was carried out using a photoionization analyser, a commercial electronic nose (e-nose) and gas chromatography ¿ mass spectrometry (GC/MS). Results indicated that removal efficiencies for both kinds of biofilters were greater than 90% at different stages of the experiment. The acclimatization periods were 10 and 25 days for the MSW biofilter and MSW-P biofilter, respectively in the experiment with ¿-pinene and 14 days for both biofilters when the MEK was the contaminant present in the air stream to treat. Removal efficiency of the system was strongly dependent upon the moisture content of the packing materials, but the nature of the contaminant (hydrophilic or hydrophobic) plays an important role in the degradation. As moisture content in the biofilters fell to below 66% (dw) for the MSW and 51% (dw) for MSW-P, the removal efficiency decreased to less than 90% when the contaminant was an hydrophobic volatile organic compound (¿-pinene). In the case of MEK, the optimal range of moisture content for the packing materials used in this experiment was between 21.5 and 67.5 % (d.w) in the case of the MSW biofilter and between 25.7 and 91.8 % (d.w) for MSW-P biofilter. E-nose and GC/MS data indicate a complete degradation of the ¿-pinene and MEK by biofiltration, although the e-nose did detect background emissions, characteristic of each type of biofilter. Also, was possible to obtain information about the performance of the biofiltration system in different stages of the experiment. Results suggest that e-nose¿s will become a more powerful tool for monitoring VOC compounds in biofiltration and composting processes in the future

Tendências em engenharia de materiais para a fabricação de células solares fotovoltaicas

Introduction: This review article was written during the second half of 2016 and the first of 2017 at the School of Environmental Engineering, Universidad Santo Tomás. Photovoltaic solar energy has acquired an important role in the global context due to the use of renewable sources and the reduction of environmental impacts, as well as for being an influential participant in meeting the current energy demand. However, it has limitations such as dependence on the availability of radiation and the use of silicon as a raw material for solar cells. Methodology: We prepared a state of the art of different databases searched, mostly Science Direct and Scopus, on the different alternative materials and current trends and their perspective of operation and implementation. Results: The solar cells that are using different materials are presented, among which the Cadmium Telluride (CdTe) solar cells stand out for their low cost and considerable efficiencies. Conclusion: Copper, indium, gallium, selenium/sulfur (cigs) cells are characterized mainly by their high adsorption coefficient; however, the great challenge to overcome is to implement them in an industrial environment. Organic solar cells are highly efficient and low-cost for their potential use in the Colombian context.Introducción: el artículo de revisión fue desarrollado durante el segundo semestre del 2016 y el primero del 2017 en la Facultad de Ingeniería Ambiental de la Universidad Santo Tomás. La energía solar fotovoltaica ha adquirido un importante papel en el contexto global por el uso de fuentes renovables y disminución de impactos ambientales, además de ser un participe influyente en la satisfacción de la demanda energética actual. No obstante, esta cuenta con limitaciones como la dependencia de la disponibilidad de radiación y el uso de silicio como materia prima de las células solares. Metodología: se realizó un estado del arte de diferentes bases de datos consultadas, en su mayoría Science Direct y Scopus, sobre los diferentes materiales alternativos y tendencias actuales, y su perspectiva de funcionamiento e implementación. Resultados: se exponen las células solares que están empleando diversos materiales, dentro de las cuales destacan las de Teluro de Cadmio (CdTe) que presentan características de bajo costo y considerables eficiencias. Conclusión: las células de cobre, indio, galio, selenio/azufre (cigs) presentan como característica principal el alto coeficiente de adsorción; no obstante, el gran reto por superar es llevar a cabo su implementación en un ámbito industrial. Las células solares orgánicas presentan una alta eficiencia y un bajo costo para su posible uso en el contexto colombiano.Introdução: o artigo de revisão foi desenvolvido durante o segundo semestre de 2016 e o primeiro de 2017 na Faculdade de Engenharia Ambiental da Universidade Santo Tomás. A energia solar fotovoltaica adquiriu um importante papel no contexto global pelo uso de fontes renováveis e diminuição de impactos ambientais, além de ser um participante influente na satisfação da demanda energética atual. Entretanto, essa conta com limitações, como a dependência da disponibilidade de radiação e o uso de silício como matéria-prima das células solares. Metodologia: foi realizado um estado da arte de diferentes bases de dados consultadas, em sua maioria, Science Direct e Scopus, sobre os diferentes materiais alternativos e tendências atuais e sua perspectiva de funcionamento e implementação. Resultados: expõe-se as células solares que estão empregando diversos materiais, dentro das quais destacam as células solares de Telureto de Cádmio (CdTe) que apresentam características de baixo custo e consideráveis eficiências. Conclusão: as células de cobre, índio, gálio, selênio/enxofre (cigs) apresentam como característica principal o alto coeficiente de absorção; no entanto, seu grande desafio a ser superado é finalizar sua implementação em um âmbito industrial. As células solares orgânicas apresentam uma alta eficiência e um baixo custo para seu possível uso no contexto colombiano

Evaluation of the Biochemical Methane Potential of Pig Manure, Organic Fraction of Municipal Solid Waste and Cocoa Industry Residues in Colombia

Colombia is a country with national policies, in order to manage, direct and guide necessary actions to treat solid waste and reduce the negative environmental impacts that these generated after their disposition. These policies are consistent with international guidelines, and it is from them that efforts are made to reduce world consumption of primary energy, thus generating interest in the potential use of biomass as a source alternative energy. The biochemical methane potential (BMP) is a test used to characterize the raw materials in trials related to the optimization of anaerobic digestion and co-digestion; it allows to find the type of substrate and co-substrate with the greatest methane potential production. This study focuses on the evaluation of the production of methane through the anaerobic process of digestion and co-digestion using three different available substrates in Colombia, of which there is very few information on the methane production potential (cocoa shell and pods), along with other common waste (organic fraction of municipal solid waste and pig manure). This evaluation was realized applying the BMP test to each individual substrate and six mixtures of these substrates; anaerobic processes of digestion and co-digestion were carried out, by testing with batch reactors of 250 mL, in mesophilic conditions (32ºC - 36ºC), obtaining the BMP of each substrate and of the mixtures. To these residues, a physical-chemical characterization was realized prior the BMP test, which was determined: values of solid volatile, total solids, organic matter and nitrogen Kjeldahl. With the obtained characterization six mixtures were prepared to evaluate: three with carbon/nitrogen (C/N) relation of 25 and three with C/N relation equal to 35. Methanation potential was also evaluated in three levels of volatile solids grams (gVs): 0.5, 1 and 2. The three residues evaluated (pig manure, cocoa shell and pods, and organic fraction of municipal solid waste) have the ability to be used for the production of methane. In the trial of BMP, the pig manure was the higher methane production with 437.33 mL CH4/gVs, followed by organic fraction of municipal solid waste with a generation of 377.25 mL CH4/gVs. The test results of anaerobic codigestion indicate that the best mix in terms of biogas production is the Mixture1, with 25 C/N relation and 0.5 gVs, which allows inferring optimal condition at the start of the experiment. This mixture reports a production of methane 2,485.91 mL CH4/gVs. The results obtained in the different tests allow visualizing that the application of this methodology serves as a valuation of the solid residues that cause a negative impact on the [email protected]