Browsing by Author "Lemos, Luís Teixeira de"
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- Characterization of MSW rejected fractions to fulfill RDF requirements and utilizationPublication . Brás, Isabel; Silva, Elisabete; Lobo, Germana; Faria, Miguel; Lemos, Luís Teixeira deIn order to fulfil European and Portuguese legal requirements, adequate alternatives to traditional municipal waste landfilling must be found namely concerning organic wastes and others susceptible of valorisation. According to the Portuguese Standard NP 4486:2008, refuse derived fuels (RDF) classification is based on three main parameters: lower heating value (considered as an economic parameter), chlorine content (considered as a technical parameter) and mercury content (considered as an environmental parameter). The purpose of this study was to characterize the rejected streams resulting from the mechanical treatment of unsorted municipal solid waste, from the plastic municipal selective collection and from the composting process, in order to evaluate their potential as RDF. To accomplish this purpose six sampling campaigns were performed. Chemical characterization comprised the proximate analysis – moisture content, volatile matter, ashes and fixed carbon, as well as trace elements. Physical characterization was also done. To evaluate their potential as RDF, the following parameters established in the Portuguese standard were also evaluated: heating value and chlorine content. As expected, results show that the refused stream from mechanical treatment is rather different from the selective collection rejected stream and from the rejected from the compost screening in terms of moisture, energetic matter and ashes, as well as heating value and chlorine. Preliminary data allows us to conclude that studied materials have a very interesting potential to be used as RDF. In fact, the rejected from selective collection and the one from composting have a heating value not very different from coal. Therefore, an important key factor may be the blending of these materials with others of higher heating values, after pre-processing, in order to get fuel pellets with good consistency, storage and handling characteristics and, therefore, combustion behavior.
- Influence of the composition of the initial mixtures on the chemical composition, physicochemical properties and humic-like substances content of compostsPublication . Silva, Elisabete; Lemos, Luís Teixeira de; Nunes, Olga C.; Cuhna-Queda, Ana CristinaThe influence of the proportion of C- and N-rich raw materials (initial C/N ratio) and bulking agent on the chemical functional groups composition, humic-like substances (HS-like) content and physicochemical properties of composts was assessed. To achieve these goals, seven initial mixtures (BA1–6 and C1) of dog food (N-rich raw material) were composted with wheat flour (C-rich raw material). Composts were analyzed in terms of chemical functional groups, physicochemical, maturity and stability parameters. The C-rich raw material favored the formation of oxidized organic matter (OM) during the composting process, as suggested by the variation of the ratios of the peaks intensity of FT-IR spectra, corresponding to a decrease of the polysaccharides and an increase of aromatic and carboxyl-containing compounds. However, although with high proportion of C-rich raw material, mixtures with low initial C/N seems to have favored the accumulation of partially oxidized OM, which may have contributed to high electrical conductivity values in the final composts. Therefore, although favoring the partial transformation of OM into stabilized HS-like, initial mixtures with high proportion of C-rich raw material but with low initial C/ N led to unstable composts. On the other hand, as long as a high percentage of bulking agent was used to promote the structure of biomass and consequently improve of the aeration conditions, low initial C/N was not a limiting factor of OM oxidation into extractable stabilized humic-like acids.
- Potential production of RDF from municipal solid waste mechanical treatment and selective collection rejected streamsPublication . Duarte, Diana; Silva, Maria Elisabete; Lemos, Luís Teixeira de; Brás, IsabelIn order to fulfill legal requirements, adequate alternatives to traditional municipal waste landfilling must be found. The valorization of some residual streams from municipal solid waste (MSW) treatment plants are among them. The purpose of this study is to characterize the rejected streams resulting from the mechanical treatment of municipal solid waste and from the yellow waste container selective collection, in order to evaluate the potential of their valorization as Refuse Derived Fuel (RDF). To accomplish this purpose, two sampling campaigns were done. Physical characteristics, proximate analysis, heating value and chlorine content were determined. As expected, results show that the refused stream from mechanical treatment and from the selective collection are rather different in overall composition, water content, energetic matter and ashes, as well as heating value and chlorine, with the last showing higher calorific value and lower moisture, therefore superior energy recovery availability. Preliminary data allows us to conclude that studied materials have a very interesting potential to be used as RDF.
- Production of Polyurethane Foams from Bark WastesPublication . Cruz-Lopes, Luísa; Rodrigues, Liliana; Domingos, Idalina; Ferreira, José; Lemos, Luís Teixeira de; Esteves, BrunoCurrently, the polyurethanes industry is dependent on fossil resources to obtain their basic raw materials (polyols and isocyanate), as these are obtained from petroleum products. The aim of this work was to use biopolyols from liquefied Pseudotsuga (Pseudotsuga menziesii) and Turkey oak (Quercus cerris) barks for the production of polyurethane foams and optimize the process. Liquefaction was done with glycerol catalyzed by KOH. Foams were produced following different formulations and using biopolyols from both barks. Subsequently, the foams were characterized according to their mechanical properties and the reaction of the foam formation was monitored by FTIR-ATR. The results show that it is possible to produce polyurethane foams using bio-based polyols and the liquefaction conditions are very important because they influence the characteristics of biopolyols and, consequently the characteristics of the foams. However, the process has to be further optimized so that it can obtain better quality foams
- Refuse Derived Fuel from Municipal Solid Waste Rejected Fractions - A case StudyPublication . Brás, Isabel; Silva, Maria Elisabete; Lobo, Germana; Cordeiro, Ana; Faria, Miguel; Lemos, Luís Teixeira dePortuguese legislation enforces adequate alternatives to municipal waste landfilling of organic wastes as well as others susceptible of valorisation. In the present work, the energetic valorisation of final municipal solid wastes rejected fractions is studied through the production of Refuse Derived Fuel (RDF). To accomplish this purpose several sampling campaigns were performed. Physical, chemical and energetic characterization of the rejected streams was done. Preliminary data allows us to conclude that studied materials have interesting potential to be used as RDF, particularly if blended with higher heating value materials in order to obtain RDF pellets with good combustion behavior, consistency and storage characteristics.
- Refuse Derived Fuel from Municipal Solid Waste rejected fractions- a Case StudyPublication . Brás, Isabel; Silva, Maria Elisabete; Lobo, Germana; Cordeiro, Ana; Faria, Miguel; Lemos, Luís Teixeira deMunicipal Solid Wastes (MSW) that contain mixtures of paper, wood, green wastes, food wastes, plastics, leather, and rubber can have energy characteristics similar to wood. Use of MSW as a fuel can be accomplished by burning the as-received material, called mass burning, but processing is often required before it can be burned effectively. The purpose is to reduce size and remove materials, valuable materials or non-combustible materials in order to be reclaimed and used as alternative fuel for sustainable disposal and converted into green and clean energy. The impact of burning these heterogeneous materials in traditional boiling systems, as primary or supplemental fuel, needs to be assessed: the physical and chemical characterization of raw materials should be performed. According to Portuguese Standard NP 4486:2008, a classification system is used based on Refuse Derived Fuel (RDF) main parameters: lower heating value, chlorine and mercury content. Higher heating value is in fact associated with paper/card, plastics, wood and textiles content and, once these materials have in their composition biogenic compounds (40-80% w/w), they become an interesting alternative fuel to accomplish the reduction of CO2 emissions.