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49 articles found

B3067 – Modeling adsorption rate of organic micropollutants present in landfill leachates onto granular activated carbon

The overall adsorption rate of single micropollutants present in landfill leachates such as phthalic acid (PA), bisphenol A (BPA), diphenolic acid (DPA), 2,4-dichlorophenoxy-acetic acid (2,4-D), and 4-chloro-2-methylphenoxyacetic acid (MCPA) on two commercial activated carbons was studied. The experimental data obtained were interpreted by using a diffusional model (PVSDM) that considers external mass transport, intraparticle diffusion, and adsorption on an active site. Furthermore, the concentration decay data were interpreted by using kinetics models. Results revealed that PVSDM model satisfactorily fitted the experimental data of adsorption rate on activated carbon. The tortuosity factor of the activated carbons used ranged from 2 to 4. The contribution of pore volume diffusion represented more than 92% of intraparticle diffusion confirming that pore volume diffusion is the controlling mechanism of the overall rate of adsorption and surface diffusion can be neglected. The experimental data were satisfactorily fitted the kinetic models. The second-order kinetic model was better fitted the experimental adsorption data than the first-order model.
Raúl Ocampo-Pérez, Mahmoud M. Abdel daiem, José Rivera-Utrilla, José D. Méndez-Díaz, Manuel Sánchez-Polo, Journal of Colloid and Interface Science 385 (2012) 174–182

B3044 – Cause and countermeasure way of rubble fires occurred after 2011 Great earthquake of Japan

This paper seeks for cause and countermeasure way of fires of huge amount of rubble which were produced after 2011 great earthquake of Japan. In 2011, we experienced many fires caused with rubbles which were produced from destroyed houses by the Great earthquake and tsunami in March 11, 2011, in Japan. Rubble includes various organic materials, and sometimes causes fires, which is used for fuel of power plants, or energy sources. It is very difficult to extinguish fire of such biomass fuel made from rubble in outdoor storage facilities. Here current studies for safety handling of these materials and proposed an evaluation method, is introduced, which is to use high sensitive calorimeters. And cause investigation work and countermeasure method, conducted by author is introduced. Our results regarding cause of fires are: initial of heat generation and fire are mostly by fermentation, and then oxidation process started after micro organism dead by high temperature, up to about 60°C. High sensitive calorimeters can detect small heat generation between room temperature and 80°C, due to fermentation or other causes. This heat generation sometimes initiated a real fire even outdoor, and produced some combustible gas. With understanding this process we recommend countermeasure way against such fires, to release heat from the pile, and prevent air entrainment into the pile to stop fermentation.
Hiroshi Koseki, Naoharu Murasawa, Yusaku Iwata, Takabumi Sakamoto, Procedia Engineering 45 ( 2012 ) 617 – 627

B2665 – Safety evaluation of sewage-sludge-derived fuels by comparison with other fuels

The utility of sewage sludge as a biomass fuel is taken as a new approach to recycle unwanted wastes as renewable energy and deal with global warming. However, safety caring of this new type of fuel is a premise before it is practically used in boilers. Thermal behaviors of four sludge-derived fuels which are under development were examined by several calorimeters (such as thermogravimetry/differential thermal analysis and C80) at temperature ramp and isothermal conditions. Heat generation at relatively low temperatures was observed. The corresponding spontaneous ignition was detected in an adiabatic spontaneous ignition tester at 80?C in some sludge species. Moreover, a certain amount of gaseous evolution was accompanied when the sludge fuels were stored at room temperature and at 60?C. Oxidation is mainly responsible for the heat and gas release from the sludge fuels. The hazards of the sewage sludge fuels were also compared with a bituminous coal and a refuse-derived fuel, which have the main feature of spontaneous ignition
Xin-Rui L, Woo-Sub Lim, Yusaku Iwata, Hiroshi Koseki, Fire Mater. 2009, 33,187–200

B1716 – Producing adsorbents from sewage sludge and discarded tyres – Characterization and utilization for the removal of pollutants from water

Adsorbent materials have been produced from sewage sludge and discarded tyres. Their physical structures and chemical surfaces differ according to their origin and production process. However, all the activated carbons show a good development of their mesopore structure. The adsorption equilibriums of methylene blue and sandolan brilliant red N-BG 125 (an industrial dye) onto the activated carbons generated have been analysed and described in terms of Freundlich isotherm. The best adsorption results were those corresponding to sandolan brilliant red onto the adsorbent obtained from sludge chemically activated with ZnCl2. The effect of temperature on the dyes adsorption was addressed and the thermodynamic parameters ( H, S and G) were determined for each of the studied systems. It was found that the process was endothermic and spontaneous in all cases.
F. Rozada, M. Otero, J.B. Parra, A. Moran, A.I. Garcia, Chemical Engineering Journal 114 (2005) 161-169

B1700 – Investigation of accidental explosion of raw garbage composting system

In November 2003 an explosion occurred at a shopping center in a room where organic waste including raw garbage is treated. Eleven people were injured including firefighters on duty and the explosion destroyed the walls of the room. To obtain a better understanding of self-heating and gas evolution processes thermal analysis, gas products analysis, spontaneous ignition test and bacterial analysis were carried out. Based on the experimental results accident scenario was investigated and it was considered that the flammable gases generated during a self-heating and combustion in a fermentation tank caused the gas explosion.
A. Miyake, M. Wakakura, T. Uchida and A. Ushikubo, Journal of Thermal Analysis and Calorimetry 85 (2006) 643-649

B1579 – Drying of municipal sewage sludge: from a laboratory scale batch indirect dryer to the paddle dryer

Among available technologies, disk and paddle dryers are often encountered in France to process municipal sewage sludge but their thermal design is still a question of know how rather than scientific knowledge. From experiments performed on an industrial Narathermâ paddle dryer and the literature, a simple model has been developed. The dryer is divided into two parts depending on the sludge consistency. A constant evaporating flow rate is assumed in the pasty zone whereas its linear decrease with the moisture content is taken into account in the granular zone. To compute this model, some of the sludge properties have to be characterized with a set of laboratory scale experimental techniques. The agreement with the experimental data is good.
P. Arlabosse, S. Chavez and C. Prevot, Brazilian Journal of Chemical Engineering 22 (2005) 227-232

B0425 – Study of the kinetics of sewage sludge pyrolysis using DSC and TGA

Thermogravimetry and differential scanning calorimetry were used to examine, in nitrogen, four sewage sludges at modest heating rates. A mechanism consisting of two independent reactions was derived for an undigested sludge. The parameters are: n1= 10, E1 = 130 kJ mol-1, A1 = 1 x 10^(18) s-1, n2 = 15, E2 = 250 kJ mol-1, A2 = 1 x 10^(25) s-1, with initial weight fractions of W1 = 0.20, W2 = 0.43, the remainder being non-reactive ash. Analysis was performed by comparing Friedman multiple-heating-rate analyses of experimental and model curves in an iterative manner. DSC experiments provide an understanding of the pyrolytic reaction mechanism and heat transfer in the thermogravimetric analyser. DSC analysis of sewage sludge was sensitive to decomposition reactions of small quantities of organic salts in the sludge. Sewage sludge could be a profitable pyrolysis feedstock if mixed with municipal solid waste.
D.L. Urban and M.J. Antal Jr., Fuel 61 (1982) 799-806

A2377 – Chemical characterization of municipal wastewater sludges produced by two-phase anaerobic digestion for biogas production

In the present study, the chemical features of municipal wastewater sludges treated in two-phase separate digesters (one for acetogenesis and the other one for methanogenesis), were characterized by using chemical analysis, stable carbon isotope ratios (?13C), HS-SPME–GC–MS, TG-DTA analysis and DRIFT spectroscopy. The results obtained showed that sludges from acetogenesis and methanogenesis differed from each other, as well as from influent raw sludges. Both processes exhibited a diverse chemical pattern in term of VFA and VOC. Additional variations were observed for ?13C values that changed from acetogenesis to methanogenesis, as a consequence of fermentation processes that led to a greater fractionation of 12C with respect to the 13C isotope. Similarly, the thermal profiles of acetogenesis and methanogenesis sludges greatly differed in terms of heat combustion produced. These changes were also supported by higher lipid content (probably fatty acids) in acetogenesis than in methanogenesis, as also shown by DRIFT spectroscopy.
Ornella Francioso, Maria Teresa Rodriguez-Estrada, Daniela Montecchio, Cesare Salomoni, Armando Caputo, Domenico Palenzona, Journal of Hazardous Materials 175 (2010) 740–746

A2354 – Intrinsic char reactivity of plastic waste (PET) during CO2 gasification

Char reactivity has a strong influence on the gasification process, since char gasification is the slowest step in the process. A sample of waste PET was devolatilised in a vertical quartz reactor and the resulting char was partially gasified under a CO2 atmosphere at 925 °C in order to obtain samples with different degrees of conversion. The reactivity of the char in CO2 was determined by isothermal thermogravimetric analysis at different temperatures in a kinetically controlled regime and its reactive behaviour was evaluated by means of the random pore model (RPM). The texture of the char was characterised by means of N2 and CO2 adsorption isotherms. The results did not reveal any variation in char reactivity during conversion, whereas the micropore surface area was affected during the gasification process. It was found that the intrinsic reaction rate of the char can be satisfactorily calculated by normalizing the reaction rate by the narrow micropore surface area calculated from the CO2 adsorption isotherms. It can be concluded therefore that the surface area available for the gasification process is the area corresponding to the narrow microporosity.
M.V. Gil, J. Fermoso, C. Pevida, J.J. Pis, F. Rubiera, Fuel Processing Technology 91 (2010) 1776–1781

A2185 – Integrated kinetics and heat flow modelling to optimise waste tyre pyrolysis at different heating rates

Pyrolysis is a promising technology to tackle the waste tyre disposal problem via converting the waste tyres into hydrocarbon fuels. This paper uses the experimental data of tyre pyrolysis (TGA/DTG and DTA) to examine both the kinetics and the heat flow at various heating rates for large tyre particles. An integrated model that considers the mass loss kinetics, exothermic kinetics, and heat flow together was developed. With the aid of the model, a multi-stage pyrolysis operation strategy is proposed. The strategy firstly starts with a heating stage to initialise the exothermic reactions in the pyrolysis. Then it changes to an adiabatic stage, where the exothermic heat is captured to facilitate the endothermic reactions afterwards. The multi-stage operation strategy achieves a significant energy saving comparing with the conventional operation strategy.
Kwok-Yuen Cheung, King-Lung Lee, Ka-Leung Lam, Chi-Wui Lee, Chi-Wai Hui, Fuel Processing Technology 92 (2011) 856–863

A2126 – Optimisation of particle size in waste tyre pyrolysis

During pyrolysis of waste tyre, the operating parameters such as tyre composition, the process temperature, the heating rate and the particle size affect the result of the pyrolysis. Some of these parameters have been closely considered but the particle size of the waste tyre is often ignored. The goal of this paper is to study the effect of particle size in waste tyre pyrolysis under different heating approaches and to use optimization techniques to determine the optimized particle size for each scenario. In this paper, the size of the waste tyre particle is considered as a major factor in determining the magnitude of the overall energy used as well as the completion time of the pyrolysis reaction. Simulations were conducted to compare the effects of the particle size on the completion time and the overall energy usage under different heating rates and operational strategies. Shredding energy needed to reduce waste tyre particles was also included into the calculation of the overall energy consumption. Optimisation of the particle size was conducted under a number of specified maximum completion times and heating rates. This study confirms the trade-off between the overall energy used and the completion time. It also shows the impact of using some optimisation techniques to determine the optimized particle size for different heating approaches.
Adetoyese Oyedun, Ka-Leung Lam, Malte Fittkau, Chi-Wai Hui, Fuel 95 (2012) 417–424

A2118 – Recycling of Waelz slag and waste foundry sand in red clay bricks

Foundry sand and Waelz slag have been used to replace clay in the production of red clay bricks. These are both problematic wastes in Northern Spain that are currently landfilled. A semi-scale industrial trial incorporating 20–40 weight percent additions to bricks has been completed. Trial samples have been compared with control bricks containing no waste additions. The physico-chemical, mechanical and environmental properties have been evaluated. Incorporating Waelz slag and foundry sand in the mix allows the production of more resource efficient, lower cost bricks. Performance benefits included improved extrusion properties during forming, lower water absorption of the sintered brick due to reduced connected porosity, significant reductions in CO2 and NOx emissions during firing and improvements in potential leachability of some pollutants in relation to samples containing only Waelz slag or foundry sand. However, it is necessary to limit the addition of Waelz slag to less than 30 wt.% in order to meet regulatory leaching limits for Mo. Other physico-chemical and mechanical parameters were not significantly affected by the addition of these industrial by-products.
Natalia Quijorna, Alberto Coza, Ana Andres, Chris Cheeseman, Resources, Conservation and Recycling 65 (2012) 1– 10

A1885 – Thermal analysis of soil amended with sewage sludge and biochar from sewage sludge pyrolysis

The main objective of the present study is to study the behaviour of sewage sludge and biochar from sewage sludge pyrolysis after addition to soil in a context of a temperate agricultural soil. For this, an incubation experiment was designed during 200 days. Carbon mineralization of soil amended with sewage sludge and biochar at two different rates (4 and 8 wt%) was evaluated. Differential thermal analysis, thermogravimetry and the first derivate of the TG were performed in oxidizing conditions on soil samples before and after incubation. Biochar obtained from sewage sludge pyrolysis at 500 °C was more stable in soil than original sewage sludge. After incubation experiment, the reduction of soil organic matter content was significantly lower in soil amended with biochar than in soil amended with sewage sludge. The thermostability index WL3/WL2 decreases after incubation in soil amended with biochar, however it increases in case of soil treated with sewage sludge.
G. Gasco, J. Paz-Ferreiro, A. Mendez, J Therm Anal Calorim (2012) 108, 769–775

A1836 – Gasification of the char derived from distillation of granulated scrap tyres

This work reports the effect of pressure on the steam/oxygen gasification at 1000 °C of the char derived from low temperature–pressure distillation of granulated scrap tyres (GST). The study was based on the analysis of gas production, carbon conversion, cold gas efficiency and the high heating value (HHV) of the product. For comparison, similar analyses were carried out for the gasification of coals with different rank. In spite of the relatively high ash ( 12 wt.%) and sulphur ( 3 wt.%) contents, the char produced in GST distillation can be regarded as a reasonable solid fuel with a calorific value of 34 MJ kgÿ1. The combustion properties of the char (EA 50 kJ molÿ1), its temperature of self-heating ( 264 °C), ignition temperature ( 459 °C) and burn-out temperature ( 676 °C) were found to be similar to those of a semi-anthracite. It is observed that the yield, H2 and CO contents and HHV of the syngas produced from char gasification increase with pressure. At 0.1 MPa, 4.6 Nm3 kgchar -1 of syngas was produced, containing 28% v/v of H2 and CO and with aHHVaround 3.7 MJ Nm-3. At 1.5 MPa, the syngas yield achieved 4.9 Nm3 kgchar -1 with 30% v/v of H2–CO and HHV of 4.1 MJ Nm-3. Carbon conversion significantly increased from 87% at 0.1 MPa to 98% at 1.5 MPa. It is shown that the char derived from distillation of granulated scrap tyres can be further gasified to render a gas of considerable heating value, especially when gasification proceeds at high pressure.
Félix A. López, Teresa A. Centeno, Francisco José Alguacil, Belén Lobato, Aurora López-Delgado, Javier Fermoso, Waste Management 32 (2012) 743–752

A1835 – Analysis of Organic Pollutants in Sewage Sludges from the Valencian Community (Spain)

Seventeen sewage sludges were studied to analyse, with the minimum number of steps, the organic pollutants that the European Union proposes to be controlled for land application. The compounds determined were a selection of polycyclic aromatic hydrocarbons (PAHs); a selection of polychlorinated biphenyls (PCBs); di(2-ethylhexyl)phthalate (DEHP); nonylphenolic compounds, including nonylphenol (NP) and nonylphenol ethoxylates with 1 and 2 ethoxy groups (NP1EO + NP2EO); extractable organic halides (EOX); and linear alkylbenzene sulphonates (LAS) with an alkylic chain of 10 to 13 carbon atoms. The results were compared with the proposed regulatory limit values, and it was observed that NP + NP1EO + NP2EO and LAS exceeded the maximums in most samples, and DEHP exceeded some of them, whereas PAHs, PCBs, and EOX almost always went beyond the limits. The values obtained are similar to those from other countries, and it can be said that it is difficult to comply with the limits for NP + NP1EO + NP2EO and LAS in many of them, although this latter parameter was not considered in the study carried out by Leschber (2004) concerning the toxicity of sewage sludge. Statistical multivariant analysis was used to look for some relationship between the results of pollutants and the characteristics of the samples, and it was found that the ratio of NP1EO + NP2EO to NP was related to sludge treatment at the sewage plant. At the same time, it was seen that the higher values of organic pollutants belonged to digested sludges
M. F. Gomez-Rico, R. Font, I. Aracil, A. Fullana, Arch. Environ. Contam. Toxicol. 52, 306–316 (2007)

A1570 – Clay–sewage sludge co-pyrolysis. A TG–MS and Py–GC study on potential advantages afforded by the presence of clay in the pyrolysis of wastewater sewage sludge

Wastewater sewage sludge was co-pyrolyzed with a well characterized clay sample, in order to evaluate possible advantages in the thermal disposal process of solid waste. Characterization of the co-pyrolysis process was carried out both by thermogravimetric–mass spectrometric (TG–MS) analysis, and by reactor tests, using a lab-scale batch reactor equipped with a gas chromatograph for analysis of the evolved gas phase (Py–GC). Due to the presence of clay, two main effects were observed in the instrumental characterization of the process. Firstly, the clay surface catalyzed the pyrolysis reaction of the sludge, and secondly, the release of water from the clay, at temperatures of approx. 450–500 °C, enhanced gasification of part of carbon residue of the organic component of sludge following pyrolysis. Moreover, the solid residue remaining after pyrolysis process, composed of the inorganic component of sludge blended with clay, is characterized by good features for possible disposal by vitrification, yielding a vitreous matrix that immobilizes the hazardous heavy metals present in the sludge.
Marco Ischia, Roberto Dal Maschio, Maurizio Grigiante, Marco Baratieri, Waste Management 31 (2011) 71–77

A1569 – Thermal analysis of growing media obtained from mixtures of paper mill waste materials and sewage sludge

This study deals with thermal analysis of growing media obtained from mixtures of paper will waste materials (one de-inking paper sludge, HP, and one reject from paper mill producing paper from virgin wood, RT) with sewage sludge. For the growing media formulation, one sewage sludge (L) was mixed with both paper mill waste materials at 10, 20, and 30% in volume. An incubation experiment was designed in order to study their carbon mineralization. Addition of sewage sludge significantly increases the carbon mineralization of growing media based on RT. In case of HP, carbon mineralization increases after addition of sewage sludge in 30% (HP + 30L treatment). Thermogravimetric analysis (TG and DTG) of growing media was performed before and after incubation experiment in order to study the organic matter transformation. The higher the carbon mineralization, the greater the difference between TG curves of samples before and after the incubation. The WL3/WL2 ratio increases after incubation of samples as a result of organic matter stabilisation. For HP growing media, the highest value corresponds to HP + 30L whereas HP + 20L, and HP + 10L show similar values. In case of RT, the WL3/WL2 index shows a progressive increase with sewage sludge content.
A. Mendez, S. Barriga, F. Guerrero, G. Gasco, J Therm Anal Calorim (2011) 104, 213–221

A1568 – Adsorbent materials from paper industry waste materials and their use in Cu(II) removal from water

This paper deals with the removal of Cu2+ from water using adsorbent materials prepared from paper industry waste materials (one deinking paper sludge and other sludge from virgin pulp mill). Experimental results showed that deinking paper sludge leads to mesoporous materials (Vmic/VT = 0.13 and 0.14), whereas the sludge from virgin pulp mill produces high microporous adsorbents (Vmic/VT = 0.39 and 0.41). Adsorbent materials were then used for Cu2+ removal from water at acid pH. During water treatment, heavy metals lixiviation from adsorbent materials was not produced. However, important Ca and Mg leaching was observed. Final pH significantly increases after treatment of water with adsorbent materials probably due to their elevated CaCO3 content. In general, highest Cu2+ removal was obtained using adsorbent materials from deinking paper sludge. This result could be due to their higher content in oxygenated surface groups, high average pore diameter, elevated superficial charge density, high CaCO3 amount and high Ca and Mg exchange content.
A. Méndez, S. Barriga, J.M. Fidalgo, G. Gascó, Journal of Hazardous Materials 165 (2009) 736–743

A1567 – Characterization and pyrolysis behaviour of different paper mill waste materials

Paper industry generates a considerable amount of wastes. Their composition mainly depends on the type of paper produced and the origin of cellulose fibres. Nowadays, in Spain, 40% of solid wastes generated by the paper and pulp industry are deposited directly in landfill, 25% are used in the agriculture, 13% in the ceramic industry and 7% in the concrete production. In the last years, thermal treatment methods like combustion, pyrolysis and gasification have been widely study as alternative techniques for the valorization of different organic waste materials. The main objective of the present work is to study the pyrolysis behaviour of different paper mill waste materials. For this reason, a wide characterization of eight paper mill waste materials from different origins was performed using SEM, FTIR, DRX and thermogravimetric techniques. Paper mill sludges from recycled paper, mainly wastes obtained from deinking process, showed high CaCO3 and clays contents. Compared with the elevated total organic matter content (TOM) of paper mill waste materials their low organic carbon content determined by Cr2O7(2-) oxidation reveals the elevated chemical stability of organic matter, due to high content on cellulose fibres. Analysis of samples by SEM indicates that successive recycled processes of paper leads to paper mill waste materials with more degraded fibres. XRD analyses show as crystalline cellulose was present in reject and primary sludge from paper mills that produced paper from virgin wood. However, crystalline cellulose content significantly decreased in waste materials from recycled paper. Finally, thermogravimetric analysis indicates that presence or mineral matter and degradation of cellulose significantly influences their pyrolysis behaviour. In general, weight loss of paper mill waste materials started at lower temperatures than pure cellulose. In waste materials from recycled paper weight loss continues at temperatures highest than 500 8C due to kaolinite dehydration and carbonates decomposition.
A. Mendez, J.M. Fidalgo, F. Guerrero, G. Gasco, J. Anal. Appl. Pyrolysis 86 (2009) 66–73

A1566 – Pyrolysis Analysis and Solid Residue Stabilization of Polymers, Waste Tyres, Spruce Sawdust and Sewage Sludge

The pyrolysis thermal treatment of several waste such as polymers (PE, PVC, PS), sewage sludge, tyres, waste wood as spruce sawdust and the successive stabilization of the pyrolysis residue has been investigated on analytical and energetic point of view. This thermal process has been considered as it allows the reduction of the waste mass with the recovery of its energy content, through the exploitation of the produced gas phase as fuel. Methods Analyzed plastics are pure polymers: Polyethylene ‘‘Riblene FF22’’ and polystyrene ‘‘Edistir 1910’’ furnished by Enichem, while polyvinylchloride has been a K57 PVC furnished by EVC. The sewage sludge sample derives from the urban wastewater treatment plant of Trento, while the waste tyre is a SMR 10 Marangoni tyre. Spruce sawdust has been furnished by a neighbouring sawmill. The pyrolysis of the above indicated solid waste was studied by thermogravimetry coupled to mass spectrometry, TG-MS and TG-GC–MS. This analytical approach was followed by pyrplysis tests, carried out on a selection of the waste materials, by using a pyrolysis bench scale reactor.
M. Grigiante, M. Ischia, M. Baratieri, R. Dal Maschio, M. Ragazzi, Waste Biomass Valor (2010) 1, 381–393

A1508 – Influence of oxygen concentration on the kinetics of cellulose wadding degradation

The kinetics of thermal decomposition of cellulose wadding was investigated from TG–MS experiments. Different oxygen concentrations in the atmosphere and several heating rates were used to study the influence of oxygen concentration on the mass loss of the sample and on the emission of gases. A shift and an amplitude variation of the DTG curves as well as an increase of the emission of gases such as CO and CO2 were observed. Then, a kinetic model was proposed to predict the mass loss of the cellulose wadding. Three stages were considered: the cellulose pyrolysis, the char oxidation and the decomposition of calcium carbonate. For the pyrolysis, the kinetic parameters were expressed according to the partial pressure of oxygen. For the char oxidation, a power law was used to account for the influence of oxygen whereas the other kinetic parameters were considered constant regardless of oxygen concentration. The decomposition of calcium carbonate was modelled by a first order influenced by the pressure of CO2.
Virginie Tihay, Christophe Boulnois, Philippe Gillard, Thermochimica Acta 525 (2011) 16-24

A1471 – Study by DTA/TG of the formation of calcium aluminate obtained from an aluminium hazardous waste

A Spanish hazardous waste from tertiary aluminium industry was used as a raw material for the synthesis of calcium aluminate. An amorphous precursor was obtained by a hydrothermal method at different values of pH. The transformation of the precursor in a crystalline aluminate was followed by TG/DTA up to 1300 °C. At temperatures between 719 and 744 °C, the precursors evolve towards the formation of C12A7 which becomes CA at circa 1016 °C. Mass spectrometry coupled to thermal analyser allowed the identification of the decomposition products.
A. Lopez-Delgado, F. A. Lopez, L. Gonzalo-Delgado, S. Lopez-Andres, F. J. Alguacil, J Therm Anal Calorim (2010) 99, 999–1004

A1438 – Etude expérimentale de la combustion d’ordures ménagères et modélisation d’un four d’incinération

Afin de comprendre et de prévoir l’évolution de polluants tels que les métaux lourds lors de l’incinération des ordures ménagères (OM), il est nécessaire de connaître les conditions physicochimiques et thermiques locales qui gouvernent leur transformation, aussi bien au niveau du lit de déchets circulant sur la grille du four d’incinération d’où ils sont émis, qu’au niveau de la chambre de postcombustion où ces derniers vont progresser, transportés par le courant gazeux ascendant. Pour y parvenir, nous étudions expérimentalement la pyrolyse et la combustion d’échantillons d’OM en utilisant la technique de la thermogravimétrie couplée à la spectrométrie de masse. L’étude expérimentale de la combustion d’un lit de déchets sur grille est abordée au moyen d'une installation pilote, instrumentée de façon à pouvoir suivre en continu l’évolution des températures au sein du lit de combustible ainsi que les concentrations de différentes espèces gazeuses. En parallèle, nous présentons un modèle de combustion du lit d’OM qui prend en compte l'ensemble des étapes de transformation de la charge (séchage, pyrolyse, oxydation du carbone résiduel), les réactions d'oxydation des gaz émis lors de l’étape de pyrolyse ainsi que les transferts thermiques par conduction, convection et rayonnement à l'intérieur du lit, considéré comme un milieu poreux. Enfin, la combustion à l’échelle du four (phase gazeuse située au-dessus du lit et chambre de post-combustion) est simulée à l’aide du code de mécanique des fluides FLUENT.
Y. Ménard, F. Patisson, Ph. Sessiecq, D. Ablitzer

A1428 – Agricultural valorisation of de-inking paper sludge as organic amendment in different soils

The objective of this study is to study the influence of de-inking paper sludge (DPS) and sewage sludge (SL) mixtures addition at different rates (2, 4 and 8%) in two soils. Incubation experiments were performed during 60 days and the influence of treatments in physical soil properties was determined by soil porosity and stability of aggregates. Differential thermal analysis (DTA) of amended soils after incubation was performed. Experimental results show that amendment increased biological soil activity, soil porosity and stability of aggregates. DTA analysis shows that the first exothermic peak generally increases with the dosage of DPS:SL due to the addition of immature organic matter. Moreover, the second peak enlarges probably due to the humification process during incubation.
Sandra Barriga, Ana Mendez, Joaqu?n Camara, Francisca Guerrero, Gabriel Gasco, J Therm Anal Calorim (2010) 99:981–986

A1402 – Adsorbent materials from paper industry waste materials and their use in Cu(II) removal from water

This paper deals with the removal of Cu2+ from water using adsorbent materials prepared from paper industry waste materials (one de-inking paper sludge and other sludge from virgin pulp mill).
A. Mendez, S. Barriga, J.M. Figalgo, G. Gasco,

A1350 – Re-cycling of sugar-ash: a raw feed material for rotary kilns

Large amounts of sugar-ash, a material rich in calcium carbonate, are produced as a by-product in the Greek Sugar Industry. This work explores the possibility of re-cycling sugar-ash for use in the lime industry. A representative sample of sugar-ash from the Plati Imathias sugar plant was studied by PXRD, TG/DTG, calcination experiments at temperatures between 650 and 1150°C and experiments to determine the quality of the quicklime produced at temperatures between 850 and 1150°C following methods described in ASTM C110 standard. The sugar-ash was found to consist of 90 wt% calcium rich minerals (calcite and monohydrocalcite) and 10 wt% amorphous material. Traces of quartz were also detected. The quicklime of highest quality was produced at 950°C. It is concluded that this "useless" material (sugar-ash) can be re-cycled for use in rotary kilns in the lime industry at calcination temperatures up to 950-1000°C.
N. Kantiranis, Waste Management 24 (2004) 999-1004

A1255 – Degradation products of the process of thermal recovery of copper from lamina scraps in lab-scale fluidized bed reactor

This paper presents experimental results dealing with a process for recovering copper in the scrap composite materials issued from electronic laminas industry. This environment-friendly process consists in the thermal treatment of scrap in a fluidized bed whose particles fix the harmful gases emitted by the organic glue gasification. A series of experiments was carried out in a thermobalance coupled to FTIR spectrometer and GC/MS with small lamina samples. These experiments demonstrated the thermal behavior of scrap composite materials, and identified the major degradation reaction gases. A series of experiments was performed with bigger scrap samples hung in a laboratory-scale fluidized bed coupled to FTIR and MS, at 350°C; the results confirmed those obtained in thermobalance. Experiments showed that a residence time lasting less than 5 min is sufficient to recover the metallic copper, and exhaust gases are not harmful.
P. Antonetti, Y. Flitris, G. Flamant, H. Hellio, D. Gauthier, B. Granier, Journal of Hazardous Materials B108 (2004) 199-206

A1243 – Formulation of muds for pelotherapy: effects of “maturation” by different mineral waters

Spa centres in northern Italy use clayey admixtures for the formulation of muds to be used in pelotherapy. The basic ingredient ("virgin" clay) is a dressed bentonitic geomaterial with mineralogical composition: smectite 60-70%, illite 5-10%, kaolinite 10-15%, quartz 5-10%, calcite 5-10% and feldspars 2-3%. The peloid muds are obtained by "maturation" of the virgin clay with mineral waters gushing out in situ which have different geochemistry: sulphureous, Ca-sulphate, Ca-Mg-sulphate and Br-I-salty (after the Italian regulation DPR 105/92). The maturation treatment is varying with respect to the mixing procedure and lasting time. Peculiar parameters have been tested to verify the effects of various maturation treatments, i.e., changes with respect to virgin clay. Formation of organic matter is due to the presence of microorganisms and algae in the maturation habitat. The < 2 µm fraction is generally decreased due to clay particles agglomeration. Mineralogical changes are mainly concerning the degradation of clay minerals, as smectite and illite, and subordinately to the dissolution of calcite. Cation exchange capacity (CEC), soluble salts, water retention, swelling index, activity, consistency parameters (WL, WP and PI), thermal behaviour and cooling kinetics are influenced by the geochemistry of mineral waters used for the maturation treatments but with some opposite trends for Br-I-salty water, and for sulphureous and Ca-sulphate waters, respectively. Noteworthy was the influence of high-pH value of the virgin clay on the pH of peloid muds (in fact, the pH of the used mineral waters is ranging around the natural value). Furthermore, the temperature reached by the peloid muds after 20 min of application (calculated after an innovative mathematical model) is influenced by water retention. An increase in plasticity index and a slower cooling are considered to improve the quality of the obtained peloid muds for pelotherapy. The observed different cation exchange behaviour and soluble salt content could be discriminant for either dermatological masks or thermal body cataplasms. A need of regulation (standard procedures) is suggested to certificate the clay geomaterials suitable for pelotherapy and also for drugs formulation.
F. Veniale, E. Barberis, G. Carcangiu, N. Morandi, M. Setti, M. Tamanini, D. Tessier, Applied Clay Science 25 (2004) 135-148

A1197 – Enhanced solubilization and removal of naphthalene and phenanthrene by cyclodextrins from two contaminated soils

The development of innovative methods for cleaning contaminated soils has emerged as a significant environmental priority. Herein, are investigated the effectiveness of cyclodextrin (CD) to solubilize and to extract organic pollutants from soils. The interactions in the cyclodextrin/pollutant/soil system have been studied "step by step" using two kinds of polycyclic aromatic hydrocarbons (PAH), naphthalene (Nap) and phenanthrene (Phe), cyclodextrins and soils. Inclusion complex formation of PAH with beta-cyclodextrin ( beta-CD) and hydroxypropyl-beta-cyclodextrin (HPCD) has been investigated and was proposed as a way to facilitate the pollutant removal from soil. Little effect of ionic strengthwas observed on CD complex formation for both compounds. The solubility of PAHin 50 g L-1 of HPCD was enhanced 20- and 90-fold for naphthalene and phenanthrene, respectively. Batch experiments were performed to study the adsorption-desorption of two PAH on two soils and the influence of CDs over these processes. These experiments were also conducted with a mixture of two PAH. The batch desorption results indicate that removal capacity of HPCD was higher than that of beta-CD. Phenanthrene was strongly sorbed on soils, this led to low desorption rates compared to that of naphthalene, whatever the extracting agent used. When HPCD solution was used as a flushing agent, 80% of naphthalene and 64% of phenanthrene recovery from soil were observed. For both compounds, the slowest desorption rate was found for the soil that had the greatest content of organic matter. CD sorption on soils, was relatively low and depended on soil type. The soil organic matter (SOM) could favor the retention of both CD and pollutant involving the extraction rate to be decreased. A competitive hydrophobic interactions of pollutant between SOM and CD molecules, and co-sorption were expected to be the mechanism for the inhibited desorption.
T. Badr, K. Hanna, C. de Brauer, Journal of Hazardous Materials B112 (2004) 215-223

A1111 – Pyrolysis study of sewage sludge by TG-MS and TG-GC-MS coupled analyses

The pyrolysis of an urban plant sewage sludge carried out under He atmosphere was studied by thermogravimetric-mass spectrometric (TG-MS) and thermogravimetric-gas chromatographic-mass spectrometric (TG-GC-MS) analyses. The sludge was thermally degraded with a heating rate of 10°C min-1 in the 20-1000°C interval; its mass loss is 51.8% up to 600°C and 61.4% up to 1000°C. Gas chromatographic analyses of the gas released during major thermogravimetric events allow the identification of various chemical species. Water, carbon mono- and di-oxide, several hydrocarbons (up to C5, both saturated and unsaturated) were the major detected species. Minor amount of pollutant species, such as cyano-compounds, were also detected. Among the released species hydrocarbons constituted the major fraction (53%), thus suggesting their immediate exploitation as fuel gas. The pyrolysis behaviour of this sample was then compared with other sewage sludge arising from wastewater treatment plants subjected to anaerobic digestion as found in literature data.
M. Ischia, C. Perazzolli, R. Dal Maschio and R. Campostrini, Journal of Thermal Analysis and Calorimetry 87 (2007) 567-574

A1105 – Grafting of calix[4]arene derivative on activated carbon surface

A new material has been synthesised by reaction between a calix[4]arene amine derivative and an oxidized activated carbon in DMF. Each reactant was characterized by thermogravimetric analysis (TGA) and diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS). In addition, the BET surface area of activated carbon, oxidized carbon and calixarene-modified carbon, were measured and are equal to 737, 519 and 351 m2/g, respectively. Results show that calixarene is linked to superficial oxygen functional groups through a covalent bond. A percentage of grafted calixarene of the order of 35% have been calculated from the results of elemental analysis.
N. Toumi, I. Bonnamour, J-P. Joly, G. Finqueneisel, L. Retailleau, R. Kalfat, R. Lamartine, Materials Science and Engineering C 26 (2006) 490 - 494

A1033 – Fitting TGA data of oil sludge pyrolysis and oxidation by applying a model free approximation of the Arrhenius parameters

Interpreting the thermal pyrolysis data from organic substances using thermogravimetric analysis (TGA) requires assuming certain formal kinetic models to be a priori for parametric fitting. The form of the assumed model limits the accuracy of stimulating the pyrolysis data. This work demonstrates the feasibility of modeling the pyrolyzed sample as a continuous mixture, in which an Arrhenius-type kinetics is applied with activation energy, pre-exponential factor, and reaction order as continuous functions of conversion. Such a data fitting scheme is not used to identify the actual chemical kinetics involved, but rather to describe the complex chemical kinetics in a unified, "model free" manner for engineering applications.
R.M. Wu, D.J. Lee, C.Y. Chang, J.L. Shie, J. Anal. Appl. Pyrolysis 76 (2006) 132-137

A1019 – Crystallization kinetics of magnetic glass-ceramics prepared by the processing of waste materials

The objective of the present investigation was to study the feasibility of conversion of an intimate mixture of blast furnace slag and blast furnace flue dust generated by a single industrial company into magnetic glass-ceramic product. Blast furnace slag (BFS) and blast furnace flue dust (BFD) are generated at a rate of 300,000 and 30,000 tons/year, respectively, from iron and steel factory. The crystallization mechanisms of a composition containing BFS and BFD in a 50/50 proportion were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The crystallization temperature was found to vary from 900 to 1100°C and two phases appeared in the crystallized samples: pyroxene Ca(Mg, Fe, Al)(Si, Al)2O6 and magnetite/maghemite. Heating rate and particle sizes effects on crystal growth of powdered samples were studied by DTA. The apparent activation energy of crystal growth using the particle size 180-315 µm was determined to be 355 and 329 kJ/mol for the first and second peak, respectively. The presence of sharp and broad crystallization peaks indicate simultaneous surface and internal crystallization mechanism. Good wear resistance and chemical durability particularly in alkaline environment, combine with good hardness and magnetic properties make this glass-ceramic material potentially useful for various industrial applications.
A.A. Francis, Materials Research Bulletin 41 (2006) 1146-1154

A1012 – 2-Mercaptothiazoline modified mesoporous silica for mercury removal from aqueous media

Mesoporous silicas (SBA-15 and MCM-41) have been functionalized by two different methods. Using the heterogeneous route the silylating agent, 3-chloropropyltriethoxysilane, was initially immobilized onto the mesoporous silica surface to give the chlorinated mesoporous silica Cl- SBA-15 or Cl-MCM-41. In a second step a multifunctionalized N, S donor compound (2-mercaptothiazoline, MTZ) was incorporated to obtain the functionalized silicas denoted as MTZ-SBA-15-Het or MTZ-MCM-41-Het. Using the homogeneous route, the functionalization was achieved via the one step reaction of the mesoporous silica with an organic ligand containing the chelating functions, to give the modified mesoporous silicas denoted as MTZ-SBA-15-Hom or MTZ-MCM-41-Hom. The functionalized mesoporous silicas were employed as adsorbents for the regeneration of aqueous solutions contaminated with Hg (II) at room temperature. SBA-15 and MCM-41 functionalized with MTZ by the homogeneous method present good mercury adsorption values (1.10 and 0.7 mmol Hg (II)/g of silica, respectively). This fact suggests a better applicability of such mesoporous silica supports to extract Hg (II) from aqueous solutions. In addition, it was observed the existence of a correlation between mercury adsorption with pore size and volume since, SBA-15 with lower areas and higher pore sizes functionalized with sterically demanding ligands, show better adsorption capacities than functionalized MCM-41.
D. Pérez-Quintanilla, I. del Hierro, M. Fajardo, I. Sierra, Journal of Hazardous Materials B134 (2006) 245-256

A0963 – Heat treatment of chlorinated waste in a rotating kiln: Problems with intermediate reaction products and solutions applied

At the CEA, the incineration of radioactive wastes is carried out thanks to the IRIS process involving a oxidizing pyrolysis step performed with a rotary kiln. If the running of the process is very satisfactory for processing waste of a given composition, it appears that the behavior of the kiln may diverge when the composition of the waste change. Through the example of wastes containing a large amount of PVC and thanks to a very simple modelling of the heating of the kiln, it has been demonstrated that the deposits are involved in overheating of the pyrolysis kiln. Fundamental investigation carried out about the thermal degradation of PVC and cellulose have shown that the formation of intermediate PVC decomposition compounds together with the residues coming from the decomposition of the cellulose could be responsible of the large amount of deposits. In order to avoid the malfunctions it has been proposed to revise the furnace operating parameters by specifying a waste feed sequence that ensure a relaxation period to the furnace. By this way, the running of the facility shows a very good stability with a very thin temperature oscillation that can easily be explained by a thermal modelling of the kiln.
F. Lemort, Y. Soudais, L. Moga, Y. Blazeck, International Journal of Engineering Science 44 (2006) 1071-1081

A0941 – Steam activation of tyre pyrolytic carbon black: Kinetic study in a thermobalance

Kinetic parameters for the steam activation of tyre pyrolytic carbon black have been determined by thermogravimetric analysis (TGA). Pyrolytic carbon black is a mainly macro and mesoporous material whose surface area can be improved via gasification to obtain microporous activated carbons. The pyrolytic carbon black sample was produced in an experimental-scale assembly where shredded tyre was pyrolysed under controlled conditions in a fixed bed reactor. Then, the activation of the resulting solid was studied by TGA using steam as activating agent. Kinetic regime was ensured fixing experimental conditions and therefore, avoiding internal and external mass transfer and heat transmission phenomena. Temperature (850-950°C) and activating gas concentration (10-40 vol.%) were the influencing variables under study. This is the first time that the random pore model (RPM) has been used to fit experimental data of the activation of pyrolytic carbon black with steam. Excellent fittings have been obtained because of the special applicability of this model to predict the behaviour of solid-fluid reactive systems, in which the solid phase shows a porous structure. Reaction evolution has successfully been modelled, including the maximum reaction rate obtained in experimental results. Additionally, intrinsic kinetic parameters of the activation reaction-reaction order, activation energy and pre-exponential factor - were calculated.
A. Aranda, R. Murillo, T. Garcia, M.S. Callén, A.M. Mastral, Chemical Engineering Journal 126 (2007) 79-85

A0846 – Evaluation of meat and bone meal combustion residue as lead immobilizing material for in situ remediation of polluted aqueous solutions and soils: “Chemical and ecotoxicological studies”

As a result of bovine spongiform encephalopathy (BSE) crisis, meat and bone meal (MBM) production can no longer be used to feed cattle and must be safely disposed of or transformed. MBM specific incineration remains an alternative that could offer the opportunity to achieve both thermal valorization and solid waste recovery as ashes are calcium phosphate-rich material. The aim of this work is to evaluate ashes efficiency for in situ remediation of lead-contaminated aqueous solutions and soils, and to assess the bioavailability of lead using two biological models, amphibian Xenopus laevis larvae and Nicotiana tabaccum tobacco plant. With the amphibian model, no toxic or genotoxic effects of ashes are observed with concentrations from 0.1 to 5 g of ashes/L. If toxic and genotoxic effects of lead appear at concentration higher than 1mg Pb/L (1 ppm), addition of only 100 mg of ashes/L neutralizes lead toxicity even with lead concentration up to 10 ppm. Chemical investigations (kinetics and X-ray diffraction (XRD) analysis) reveals that lead is quickly immobilized as pyromorphite [Pb10(PO4)6(OH)2] and lead carbonate dihydrate [PbCO3.2H2O]. Tobacco experiments are realized on contaminated soils with 50, 100, 2000 and 10 000 ppm of lead with and without ashes amendment (35.3 g ashes/kg of soil). Tobacco measurements show that plant elongation is bigger in an ashes-amended soil contaminated with 10 000 ppm of lead than on the reference soil alone. Tobacco model points out that ashes present two beneficial actions as they do not only neutralize lead toxicity but also act as a fertilizer.
E. Deydier, R. Guilet, S. Cren, V. Pereas, F. Mouchet, L. Gauthier, Journal of Hazardous Materials 146 (2007) 227-236

A0825 – Kinetic model identification and parameters estimation from TGA experiments

The presented work is a part of an ongoing research effort on the development of a general methodology for the determination of kinetic models of solid thermal decomposition under pyrolysis conditions with thermogravimetric analysis (TGA) devices. The goal is to determine a simple and robust kinetic model for a given solid with the minimum of TGA experiments. From the latter point of view, this work can be seen as the optimal design of TGA experiments for pyrolysis kinetic modelling. In this paper, a general procedure is presented and more precise results are given about the influence of the sensitivity matrix on the estimation of the kinetic parameters and about the important influence of the specific TGA runs used for parameter estimation on the precision of the fitted parameters. The first results are shown for simulated applications; in the final part, the presented results concern cellulose pyrolysis in a Setaram TGA device.
C. Reverte, J-L. Dirion, M. Cabassud, J. Anal. Appl. Pyrolysis 79 (2007) 297-305

A0807 – The application of thermal processes to valorise waste tyre

Scrap tyres are a growing environmental problem because they are not biodegradable and their components cannot readily be recovered. In this investigation, the thermochemical recycling of rubber from old tyres by pyrolysis and the value of the products obtained have been studied. First, thermobalance experiments were carried out, studying the influence of the following variables: heating rate, flow rate, particle size and temperature. These thermobalance results were extended by performing experiments in a fixed bed reactor, studying the effect of the main process variables on yields of derived products: oils, gases and solid residue. The oils have been characterized using a combination of analytical techniques (TLC-FID, GC-MS and simulated distillation). No relationship between functional group composition of the oils determined by TLC-FID and process variables was found. The carbonaceous material obtained was characterized by N2 and CO2 adsorption. The possible uses of this char have been analyzed taking into account and calculating the emissions that would be produced if the char were burnt.
R. Murillo, E. Aylon, M.V. Navarro, M.S. Callén, A. Aranda, A.M. Mastral, Fuel Processing Technology 87 (2006) 143 - 147

A0798 – Crystal phase separation and microstructure of a thermally treated vitrified solid waste

The vitrification method was used to stabilize a solid industrial waste residue rich in iron and lead oxides. Upon devitrification of the glass products, the effect of batch composition on the ability to produce glass-ceramic materialswas investigated by electron microscopy techniques. The crystallization and microstructural evolution of the vitreous products was explored with respect to the annealing conditions. In the course of vitrification, ferric oxide functioned as a glass network former, contributing to the structural integrity of the vitreous matrix. After thermal treatment of the vitrified products, at temperatures determined by differential thermal analysis, Pb8Fe2O11, PbFe12O19 and Fe2O3 were the dominant crystal phases detected in the glass-ceramic products, the former characterized as a new structure. The distribution of iron and lead oxides among different crystalline phases was found to be the dominant parameter determining the efficiency of lead captivation into the volume of the devitrified products, whereas in glass products lead is diffused in the amorphous matrix.
Th. Kehagias, Ph. Komninou, P. Kavouras, K. Chrissafis, G. Nouet, Th. Karakostas, Journal of the European Ceramic Society 26 (2006) 1141-1148

A0786 – Effect of improving flue gas cleaning on characteristics and immobilisation of APC residues from MSW incineration

The flue gas cleaning system of a MSW incinerator with a capacity of 350 kt/year was changed to improve the HCl elimination efficiency. Instead of the semi-wet operating spray reactor and subsequent baghouse, a two-step wet flue gas cleaning was added behind the baghouse. Elemental composition, X-ray powder diffraction patterns and TGA measurements showed that the resulting APC residue was totally different from the former residue. As a consequence, leaching characteristics of both residues also differed and another treatment was required prior to disposal. For the former residue, mainly leaching of Pb (>100 mg/l), necessitated treatment prior to landfilling. The lower alkalinity of the new residue resulted in a leachate pH of 9.7 and a Pb concentration of 0.8 mg/l. The leachate pH of the former residue was 12.4. The leaching of Pb and Zn increased above 100 mg/l when immobilising the new residue with cement. Better results were obtained when immobilising with micro silica. The high CaCl2.2H2Ocontent of the newresidue brought along clogging of the bag filter system. Adding 1.4% of CaO (or 1.9% of Ca(OH)2) to the residue already improved these inconveniences but again significantly changed the leaching behaviour of the residue.
D. Geysen, C. Vandecasteele, M. Jaspers, E. Brouwers, G. Wauters, Journal of Hazardous Materials B128 (2006) 27-38

A0751 – Characterization and possible uses of ashes from wastewater treatment plants

This work, on the ashes from the wastewater treatment plant of Galindo (Vizcaya, Spain), has been outlined with the purpose of finding their physico-chemical properties and suggesting possible applications. Ashes contain important quantities of iron, calcium, silica, alumina and phosphates. X-Ray diffraction data make it possible to estimate the mineralogical compositions of the original ashes and also, after thermal treatment at 1200 and 1300°C, the main reactions occurring in thermal treatment. Particle size analysis makes it possible to classify ashes as a very fine powdered material. The thermal treatment leads to a densification of the material and provokes losses of weight mainly due to the elimination of water, carbon dioxide and sulphur trioxide. Application tests show that ashes are not suitable for landfill and similar applications, because of their plastic properties. Testing for pozzolanic character, after the ashes had been heated at 1200°C, did not lead to a strong material probably due to low contents in silica and alumina or to requiring a higher heating temperature. Thermal treatment leads to densification of the material with a considerable increase of compressive strength of the probes. The use of additives (clays and powdered glass) to improve ceramic properties of ashes will be the aim of a future work.
I. Merino, L.F. Arévalo, F. Romero, Waste Management 25 (2005) 1046-1054

A0656 – Energy demand in sludge dewatering

This work investigates the energy required to dewater a suspension, i.e., activated sludge dewatered by centrifugation or consolidation.Total energy input to the suspension from the dewatering device, bond strength between adjacent water and solid surface, and intra-cake friction loss were evaluated for original and flocculated sludges.In centrifugal dewatering, most energy input during the initial stage was consumed by overcoming process irreversibility other than intra-cake friction, and, thereby, had a low energy efficiency.To increase centrifuge speed or to flocculate the sludge at optimal flocculant dosage would yield a high-energy input.In the consolidation test, most energy input at the initial stage was consumed in breaking down the bond strength until the moisture content reduced to less than the critical content.During subsequent dewatering stages, friction loss became the dominant source of energy loss.Dewatering sludge with high-energy efficiency is beneficial to optimally operate a dewatering process.
C.P. Chu, D.J. Lee, C.Y. Chang, Water Research 39 (2005) 1858-1868

A0639 – Physical and chemical characterisation of crude meat and bone meal combustion residue: “waste or raw material?”

As a result of the recent bovine spongiform encephalopathy (BSE) crisis in the European beef industry, the use of animal by-product is now severely controlled. Meat and bone meal (MBM) production can no longer be used to feed cattle and must be safely disposed of or transformed. Main disposal option is incineration, producing huge amounts of ashes the valorisation of which becomes a major concern. The aim of this work is to characterise MBM combustion residue in order to evaluate their physical and chemical properties to propose new valorisation avenues. The thermal behaviour of crude meat and bone meal was followed by thermogravimetric analysis (TGA) and (24 wt.%) inorganic residue was collected. The resulting ashes were characterised by powder X-ray diffraction (XRD), particle size distribution, specific surface area (BET), scanning electron microscopy (SEM) couple with energy disperse X-ray analysis (EDX). Elemental analysis revealed the presence of chloride, sodium, potassium, magnesium with high level of phosphate (56 wt.%) and calcium (31 wt.%), two major constituents of bone, mainly as a mixture of Ca10(PO4)6(OH)2 and Ca3(PO4)2 phases. The impact of combustion temperature (from 550 to 1000°C) on the constitution of ashes was followed by TGA, XRD and specific surface measurements. We observed a strong decrease of surface area for the ashes with crystallisation of calcium phosphates phases without major changes of chemical composition.
E. Deydier, R. Guilet, S. Sarda, P. Sharrock, Journal of Hazardous Materials B121 (2005) 141-148

A0606 – Kinetic models for the pyrolysis and combustion of two types of sewage sludge

Pyrolysis and combustion of two types of sewage sludge have been studied. The two sludges considered, considering their thermal decomposition, have different behaviors when comparing pyrolysis and combustion TG runs of each sludge. In one case, the combustion can be considered as an oxidative pyrolysis, where the decomposition process is accelerated by the presence of oxygen. In the other case, the TG combustion run has two parts, the first one coinciding with the pyrolysis run and the second one with combustion of the char formed previously. For the pyrolysis of each sludge, three thermogravimetric runs at different heating rates (5, 15 and 30 K/min) were carried out to obtain a kinetic model, considering three parallel reactions. Following the simplex method, and with the same set of parameters for the three runs, and for each one of the three fractions considered, the values of pre-exponential factors, the apparent activation energies (103.9, 169.7 and 209.4 kJ/mol), the reaction orders and the maximum amount of volatiles were obtained. A discussion of the different values, in comparison with others obtained from literature is presented. Following a similar methodology, for the combustion of each sludge, two series of three runs at different oxygen concentrations (10 and 20%) and heating rates were carried out. For the sludge with oxidative pyrolysis behaviour, the scheme of three parallel reactions (as in pyrolysis) was appropriate for correlating the data, using the same values of activation energy, reaction order and maximum amount of volatiles evolved, and optimizing only the value of the pre-exponential factor, that is correlated with oxygen pressure. On the other hand, for the other sludge, with the first stage coinciding with pyrolysis and the second stage concerning the char combustion, the kinetic parameters of the second stage are obtained, with an apparent activation energy of 144.1 kJ/mol.
R. Font, A. Fullana, J. Conesa, J. Anal. Appl. Pyrolysis 74 (2005) 429-438

A0605 – Thermogravimetric study of different sewage sludges and their relationship with the nitrogen content

The pyrolysis and combustion of 17 sewage sludges were studied by thermogravimetry. The dynamic experiments were carried out at 10°C min-1, and three different behaviours were observed at the decomposition curves. One of them shows combustion and pyrolysis curves that are parallel until high temperatures, and so the combustion process can be considered as an oxidative pyrolysis. The DSC combustion curve shows that exothermic processes take place during most of the combustion run. The second behaviour shows combustion and pyrolysis curves that approximately coincide at low temperatures, but at high temperatures the combustion curve falls strongly, indicating that the combustion really occurs at high temperatures. The DSC curve shows that the exothermic process corresponds only to the combustion process. Some sludges with this behaviour show a combustion curve above the pyrolysis curve at a range of temperatures that also happens to BSA protein. The third behaviour is intermediate between the first and second behaviours, where the DSC curve shows exothermic processes during the first part and during the combustion of the char formed. Total nitrogen content, nitrogen content in decomposed fraction from combustion and a parameter that is associated to the decomposition of proteins were also studied and it was observed that there is a relationship between all of them and the type of behaviour in thermogravimetry.
M.F. Gomez-Rico, R. Font, A. Fullana, I. Martin-Gullon, J. Anal. Appl. Pyrolysis 74 (2005) 421-428

A0603 – Assessment of tire devolatilization kinetics

In this paper, a kinetic study of the devolatilization of tire rubber has been performed in a thermobalance using nitrogen as carrier gas. The main operation variables have been studied including flow rate, particle size, final temperature and heating rate, observing that only temperature has a remarkable effect on tire rubber conversion. Kinetic parameters have been calculated and used to simulate all experimental curves including the ones obtained at different heating rates. In addition, an approximate tire rubber composition has been obtained by integrating the reaction rate versus temperature curves. The suitability of the kinetic parameters has been demonstrated in real conditions by performing experiments in a fixed bed reactor. Finally, the conclusions achieved from this study can be used not only for pyrolysis process design but also for the interpretation and modeling of the tire rubber combustion process.
E Aylon, M.S. Callén, J.M. Lopez, A.M. Mastral, R. Murillo, M.V. Navarro, Slawomir Stelmach, J. Anal. Appl. Pyrolysis 74 (2005) 259-264

A0602 – Pyrolysis of waste tyres in an atmospheric static-bed batch reactor: Analysis of the gases obtained

Scrap tyre pyrolysis was studied under nitrogen atmospheric pressure in order to analyse temperature influence on the global yields and the gas composition. A static-bed batch reactor was used to pyrolyse 300 g of shredded scrap tyres at temperatures from 400 to 700°C. The reactor was externally heated by means of electrical resistances, the heating rate being approximately 12 K min 1. Once the required system temperature was reached and stabilised, it was maintained for 4 h. The residence time of the gas in the reactor was calculated, with values falling between 1 and 1.5 min. Three phases were obtained after pyrolysis: solid (char), liquid (water and oils) and gas (light hydrocarbons, H2, CO and CO2). The product distribution and composition were studied as a function of the thermal treatment. Global yields were determined as follows: char, 47-63 wt.%, oils, 30-43 wt.%, and gas, 2.4-4.4 wt.%. It was observed that the liquid yield increases with temperature from 400 to 500°C. However, from 500°C on, this parameter remained almost constant. The solid yield followed an inverse trend to that observed for the liquid yield. On the other hand, the gas yield showed a slight continuous growth with temperatures ranging from 400°C (2.4 wt.%) to 700°C (4.4 wt.%). The gas phase was analysed off-line by gas chromatography. The main gases produced from the pyrolysis process were H2, CO, CO2 and hydrocarbons: CH4, C2H4, C3H6 and C4H8. It was observed that the fraction of light gases (H2, CO, CO2 and CH4) was greater at higher temperatures.
C. Berrueco, E. Esperanza, F.J. Mastral, J. Ceamanos, P. Garcia-Bacaicoa, J. Anal. Appl. Pyrolysis 74 (2005) 245-253

A0440 – Chemometrics as a tool for the analysis of evolved gas during the thermal treatment of sewage sludge using coupled TG-FTIR

The thermal decomposition of sewage sludge has been investigated using coupled TG-FTIR for long time experiment (10 h). The exploitation of the resulted data from FTIR is performed by the SIMPLe-to-use interactive self-modelling mixture analysis (SIMPLISMA) method and allows to identify some of the evolved gases and to obtain their relative concentration profiles versus time without prior knowledge of constituents. As shown, this method can work properly for mixture with overlapped bands but some compounds remain "invisible" to FTIR analysis. More of that for long time experiment, it is possible to extract a spectrometer baseline contribution, which contributes to minimise noise and time variation.
J.H. Ferrasse, S. Chavez, P. Arlabosse, N. Dupuy, Thermochimica Acta 404 (2003) 97-108