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The Thermochemical Conversion of Municipal Solid Waste by Torrefaction Process
Maja Ivanovski, Darko Goričanec, Danijela Urbancl, 2023, original scientific article

Abstract: In this work, the thermochemical properties of municipal solid waste (MSW) are studied using the torrefaction process as the main method for investigation. Torrefaction experiments were carried out using an electric laboratory furnace, at temperatures of 200, 250, and 300 °C. The residence time was set to 90 min. Proximate and ultimate analysis were performed on the torrefied MSW samples and compared with the properties of the raw MSW samples. In addition, the thermal properties of the obtained torrefied MSW samples were evaluated by thermogravimetric analysis (TGA) and derivative thermogravimetric analysis (DTG). The following could be stated: the obtained results showed that mass and energy yields (MY and EY, respectively) decrease with increasing when torrefaction temperature, while the heating values (HHV) increased under the same conditions (from 24.3 to 25.1 MJ/kg). Elemental analysis showed an increase in carbon content (C), from 45.7 ± 0.9 to 52.8 ± 1.05 wt.%, and decrease in oxygen content (O), from 45.6 ± 0.9 to 39.5 ± 0.8 wt.%, when torrefaction temperature is increased, which is consistent with the general definition of the torrefaction process. In addition, enhancement factors (EFs) and fuel ratios (FRs) were calculated, which ranged from 1.00 to 1.02 and 0.16 to 0.23, respectively. Some anomalies were observed during the thermal analysis, which are assumed to be related to the composition of the selected MSW. This study therefore shows that torrefaction pretreatment can improve the physicochemical properties of raw MSW to a level comparable to coal, and could contribute to a better understanding of the conversion of MSW into a valuable, solid biofuel.
Keywords: biomass, municipal solid waste, torrefication, energy yield, thermogravimetric analysis
Published in DKUM: 10.05.2024; Views: 156; Downloads: 11
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An analysis of the responsibility for zero waste
Ivana Tršelič, Daniel Rolph Schneider, Niko Samec, Filip Kokalj, 2019, original scientific article

Abstract: European Union Directive 2008/98/EC sets the priority hierarchy of the prevention of waste, re-using waste, recycling waste, waste recovery, and waste disposal. Although every one of us is in daily contact with waste, we do not have the knowledge that can lead us to the sound management of waste from the beginning, before products are identified as waste. Zero waste is a fundamental concept of the sustainable community of the future. It is a phrase frequently used by politicians seeking to upgrade the municipal solid waste management systems in their communities. In this manner, the responsibility of zero waste is given to the waste management process instead of to householders. Householders then equate waste prevention with recycling and the proper waste management of the collectors, public services, or waste management company. In reality, zero waste starts with each one of us at home. Households should aim to reduce consumption and undertake repairs to extend the life span of products. Behaviour change can only start with knowledge. In reality, waste prevention does not include recycling. Recycling leads to a combined reduction of waste brought to landfill and raw material extraction. The present paper evaluates household waste to clarify the facts. It analyses the composition of three streams: municipal solid waste, separately collected packaging waste, and bulky waste in different regions of Slovenia. The research defines waste into five different categories. The first category is waste that can and should be avoided. The second category is waste that can be re-used. Further on, the research expands by researching the market of the third category that defines recyclables, which waste can be recycled; the last two categories are the waste that we are fighting with at the end of the waste management process, either to make it to the waste-to-energy process or to comply with landfill restrictions. At the end of the research, we summarize the situation of household waste in 2018. Our goal is to reduce the quantity of waste, making only waste that can be recycled. If we consider waste prevention to be a fight against waste, we can put our plan in place by taking the first step: getting to know our enemy.
Keywords: municipal solid waste, zero waste, recycling, lightweight packaging waste, waste management, material recovery
Published in DKUM: 05.12.2023; Views: 310; Downloads: 7
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Analysis of combustible fractions in mixed municipal waste and packaging and calculation of energy value
Ivana Tršelič, Simon Jerina, Sebastijan Seme, Janja Stergar, 2020, original scientific article

Abstract: The present article analyses combustible fractions in mixed municipal waste and packaging and the calculation of energy value. Methods of thermal treatment of waste and methods of preparation of alternative fuels and classifications are presented and described. The article describes the method of analysis of caloric values with which we determined the energy values of individual fractions. For the research, we also used two thermal analyses, with which we considered individual fractions, thermogravimetric analysis, and differential dynamic calorimetry. The article presents the results of both thermal analyses, with which we observe the responses of individual types of plastics at different temperatures and the change in physical and chemical properties. The problem we have analysed in this article is mainly recyclable plastic that can no longer be reused due to various factors. The results of the structural analysis of household waste collection are also presented and described; on the basis of the analysis, the energy value of the container of mixed municipal waste and the reasonableness of waste reuse are recalculated.
Keywords: mixed municipal waste, mixed municipal packaging, combustible fractions, energy value, solid recovered fuel, TGA analysis
Published in DKUM: 04.12.2023; Views: 209; Downloads: 6
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Utilization of bottom ash from the incineration of separated wastes as a cement substitute
Filip Kokalj, Niko Samec, Bernardka Jurič, 2005, original scientific article

Abstract: Waste incineration is still an essential technology in the concept of integrated waste management. Most of the combustion residues are incinerator bottom ash. It has been discovered that incinerator bottom ash from the incineration of separated waste in the primary chamber of the modular two-stage incinerator mainly consists of metal oxides, especially SiO2 and CaO, in proportions that are quite similar to those in cement and so the feasibility of its application as a substitute for cement in concrete was investigated. It was found that after 28 days, the flexural and compressive strengths of the binder using bottom ash were practically comparable with those of a pure cement mixture. The results show that it is reasonable to use a binder containing incinerator bottom ash for applications in which an early-stage lower strength of concrete element is acceptable.
Keywords: waste management, solid municipal waste, separated wastes incineration, bottom ash, cement, concrete
Published in DKUM: 01.06.2012; Views: 2229; Downloads: 134
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Numerical optimisation of a waste-to-energy plant's operating parameters using CFD
Miran Kapitler, Niko Samec, Filip Kokalj, 2011, original scientific article

Abstract: The combustion process for using municipal solid waste as a fuel within a waste to energy plant calls for a detailed understanding of the following phenomena. Firstly, this process depends on many input parameters such as proximate and ultimate analyses, the season of the year, primary and secondary inlet air velocities and, secondly, on output parameters such as the temperatures or mass-flow rates of the combustible products. The variability and mutual dependence of these parameters can be difficult to manage in practice. Another problem is how these parameters can be tuned to achieving optimal combustible conditions with minimal pollutant emissions, during the plant-design phase. in order to meet these goals, a waste-to-energy plant with bed combustion was investigated by using computational fluid-dynamics approach. The adequate variable input boundary conditions based on the real measurement are used and the whole computational work is updated using real plant geometry and the appropriate turbulence, combustion, or heat transfer models. The operating parameters were optimized on output parameters through a trade-off study. The different operating conditions were varied and the combustible products were predicted and visualized. Finally, the response charts and matrix among the input and output parameters during the optimization process are presented, which monitored the dependence among these parameters.
Keywords: municipal solid waste, bed combustion, computational fluid dynamics, numerical optimization, goal driven optimization, trade-off study, parameters correlation
Published in DKUM: 01.06.2012; Views: 2017; Downloads: 173
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