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ABSTRACT: This work aimed to study the recovery of two types of waste by the process of pyrolysis. The obtained results show that the
adding of a plastic mix improves the overall efficiency of the slow pyrolysis of pine. Therefore, it was possible to achieve
higher liquid yields and less solid product than in the classic slow pyrolysis carbonization of biomass. The obtained liquids
showed heating values similar to that of heating fuel oil. The gas products had energetic contents superior to that of producer
gas, and the obtained solid fractions showed heating values higher than some coals. There were also identified some typical
products of fast biomass pyrolysis used as raw material in several industries. The effects of experimental conditions in product
yield and composition were also studied. The parameters that showed higher influence were (with its increase): reaction time
on gas product composition (increase of the alkane content) and on liquid composition (increase in aromatics content); reaction
temperature on product yield (decrease of liquid yield with increase of solids and gases) and on gas product composition (increase
in alkane content); initial pressure on liquid composition (increase in the aromatics content) and mainly the pine content
of the initial mixture on products yield (increase of gas and solid yield with a decrease in liquids) and on the gas product
composition (favouring CO and CO2 formation).
Clean Technologies and Environmental Policy 04/2012; 11(1):115-122. · 1.75 Impact Factor
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ABSTRACT: This paper presents the study of the combustion of char residues produced during co-gasification of coal with pine with the aim of characterizing them for their potential use for energy. These residues are generally rich in carbon with the presence of other elements, with particular concern for heavy metals and pollutant precursors, depending on the original fuel used. The evaluation of environmental toxicity of the char residues was performed through application of different leaching tests (EN12457-2, US EPA-1311 TCLP and EA NEN 7371:2004). The results showed that the residues present quite low toxicity for some of pollutants. However, depending on the fuel used, possible presence of other pollutants may bring environmental risks. The utilization of these char residues for energy was in this study evaluated, by burning them as a first step pre-treatment prior to landfilling. The thermo-gravimetric analysis and ash fusibility studies revealed an adequate thermochemical behavior, without presenting any major operational risks. Fluidized bed combustion was applied to char residues. Above 700°C, very high carbon conversion ratios were obtained and it seemed that the thermal oxidation of char residues was easier than that of the coals. It was found that the char tendency for releasing SO(2) during its oxidation was lower than for the parent coal, while for NO(X) emissions, the trend was observed to increase NO(X) formation. However, for both pollutants the same control techniques might be applied during char combustion, as for coal. Furthermore, the leachability of ashes resulting from the combustion of char residues appeared to be lower than those produced from direct coal combustion.
Waste Management 09/2011; 32(4):769-79. · 2.43 Impact Factor
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ABSTRACT: Two combustion tests were performed in a fluidized bed combustor of a thermo-electric power plant: (1) combustion of coal; (2) co-combustion of coal (68.7% w/w), sewage sludge (9.2% w/w) and meat and bone meal (MBM) (22.1% w/w). Three samples of ashes (bottom, circulating and fly ashes) were collected in each combustion test. The ashes were submitted to the following assays: (a) evaluation of the leaching behaviour; (b) stabilization/solidification of fly ashes and evaluation of the leaching behaviour of the stabilized/solidified (s/s) materials; (c) production of concrete from bottom and circulating ashes. The eluates of all materials were submitted to chemical and ecotoxicological characterizations. The crude ashes have shown similar chemical and ecotoxicological properties. The s/s materials have presented compressive strengths between 25 and 40 MPa, low emission levels of metals through leaching and were classified as non-hazardous materials. The formulations of concrete have presented compressive strengths between 12 and 24 MPa. According to the Dutch Building Materials Decree, some concrete formulations can be used in both scenarios of limited moistening and without insulation, and with permanent moistening and with insulation.
Waste Management 05/2011; 31(9-10):2009-19. · 2.43 Impact Factor
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ABSTRACT: A method for the determination of 15 aromatic hydrocarbons in eluates from solid residues produced during the co-pyrolysis of plastics and pine biomass was developed. In a first step, several sampling techniques (headspace solid phase microextraction (HS-SPME), static headspace sampling (HS), and dispersive liquid-liquid microextraction (DLLME) were compared in order to evaluate their sensitivity towards these analytes. HS-SPME and HS sampling had the better performance, but DLLME was itself as a technique able to extract volatiles with a significant enrichment factor. HS sampling coupled with GC-MS was chosen for method validation for the analytes tested. Calibration curves were constructed for each analyte with correlation coefficients higher than 0.999. The limits of detection were in the range of 0.66-37.85 ng/L. The precision of the HS method was evaluated and good repeatability was achieved with relative standard deviations of 4.8-13.2%. The recoveries of the analytes were evaluated by analysing fortified real eluate samples and were in the range of 60.6-113.9%. The validated method was applied in real eluate samples. Benzene, toluene, ethylbenzene and xylenes (BTEX) were the compounds in higher concentrations. The DLLME technique coupled with GC-MS was used to investigate the presence of less volatile contaminants in eluate samples. This analysis revealed the presence of significant amounts of alkyl phenols and other aromatic compounds with appreciable water solubility.
Talanta 11/2009; 80(1):104-8. · 3.79 Impact Factor
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ABSTRACT: The co-combustion of sewage sludge (SS) and coal is widely used for the treatment and thermal valorization of SS produced in wastewater treatment plants. The chemical and ecotoxicological properties of the ashes produced in this thermal treatment have not been fully studied. Two combustion tests were performed in a fluidized bed combustor. Colombian coal was used as fuel in test A. A blend (1+1) of this coal and a stabilized SS (Biogran) was used in a second test B. Samples of the bottom and fly ashes trapped in two sequential cyclones were collected. The characterization of the ashes was focused on two main aspects: (1) the bulk content of a set of metals and (2) the characterization of eluates produced according to the European Standard leaching test EN 12457-2. The eluates were submitted to an ecotoxicological characterization for two bio-indicators. In what concerns the bulk content of ashes, both combustion tests have produced ashes with different compositions. The ashes formed during the co-combustion test have shown higher concentrations of metals, namely Cr, Cu, Ni, Pb, Zn and Fe for all ashes. The leaching test has shown low mobility of these elements from the by-products produced during the combustion and co-combustion tests. Cr and Cr(VI) were mainly detected in the eluates of the 1st cyclone ashes produced in both combustion tests and in the 2nd cyclone ashes produced in the co-combustion test. Considering the ecotoxicity assays, the eluates of bottom and fly ashes for both combustion and co-combustion tests have shown low ecotoxic levels. The micro-crustacean Daphnia magna was generally more sensitive than the bacterium Vibrio fischeri. CEMWE criterion has allowed to classify the bottom ashes for both combustion and co-combustion tests as non-toxic residues and the fly ashes collected in both cyclones as toxic.
Journal of hazardous materials 06/2009; 170(2-3):902-9. · 4.14 Impact Factor
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ICheaP-8 - The Eight International Conference on Chemical and Process Engineering; 01/2007
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ABSTRACT: This paper presents a study of pollutant emissions during combustion tests of sewage sludge in a pilot fluidized-bed system. Mono-combustion of sludge and its co-combustion with coal were compared with combustion of coal alone. It was verified that the high N content in the sludge did not lead to an increase in NOx production and that air staging gave rise to very low levels of NO emissions. SO2 diminished when the sludge was introduced, but achieving acceptable levels to meet emission limits still required the use of limestone. The emissions of heavy metals were increased during co-combustion but decreased during sludge mono-combustion, with the exception of Hg, which was retained more efficiently in cyclone ashes during co-combustion. The study of the dependence of the Pb and Cd distributions on the diameter of the fly ash emitted showed that these metals were associated with particles with an average diameter of 2−3 μm and that their removal would only be possible with adequate gas cleaning.
07/2004;
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ABSTRACT: As a consequence of the growing awareness of the need to protect the environment, a study was undertaken to investigate the impact of the use of recycled waste oils as an industrial fuel in relatively small industrial units. Combustion tests were carried out in a 240 kW experimental furnace with oils that had been subjected to pretreatment involving centrifugal separation of solids present. However, the analysis of the combustion gases demonstrated that the levels of principal contaminants such as lead and other heavy metals were still too high to meet the emission levels required by the European Union. This suggests that physical processes are inadequate to remove the contaminants present in waste oils.
Fuel. 75(8):940-944.
