1. Energy demand distribution and environmental impact assessment of chitosan production from shrimp shellsFilipa A. Vicente, Robert Hren, Uroš Novak, Lidija Čuček, Blaž Likozar, Annamaria Vujanović, 2024, original scientific article Abstract: Step towards resilience and sustainability through exploring renewable biomass and waste streams to produce higher-added value products and energy is among key aspects for closing the loops, saving resources, and reducing the resource and emission footprints. In that respective, crustacean shells waste can offer rich spectre of valuable compounds such as proteins, chitin, carotenoids. This waste is produced in large quantities worldwide, thus allowing for commercial valorisation. An overview of technologies is undertaken for more sustainable and environmentally friendly chitosan production via chitin isolation and conversion and compared to the conventional processes. Furthermore, an assessment of the environmental burden and energy demand distribution for conventional and more sustainable alternative processes was performed, based on lab-scale experimental data. Three different chitin extraction routes and three distinct chitosan conversion processes were considered and compared for their greenhouse gas footprint, abiotic depletion, acidification, eutrophication and other potentials. Finally, the energy demand distribution was analysed considering electricity production patterns from three European countries, Slovenia, Portugal and Norway. The results showed that alternatives 3-A and 3-B (conventional eco-solvents - conventional deacetylation with 40 % and 50 % NaOH) generate the lowest environmental burden (184 g CO2 eq./g chitosan). Electricity was the main hotspot of the processes, used either for extraction, plasma treatment or deacetylation. The sensitivity analysis proved that the Norwegian electricity mix has the lowest environmental impact (4.2 g CO2 eq./g chitosan). This study highlights the impact of blue biorefineries by transforming marine waste to valuable biopolymers such as chitin and chitosan.
Keywords: shrimp shells waste, blue biorefinery, value-added products, chitosan, sustainable production, comparative environmental assessment
Published in DKUM: 08.01.2025; Views: 1; Downloads: 0
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2. Decomposition and fragmentation of conventional and biobased plastic wastes in simulated and real aquatic systemsOlivija Plohl, Lidija Fras Zemljič, Alen Erjavec, Noemi Sep, Maja Čolnik, Yee Van Fan, Mojca Škerget, Annamaria Vujanović, Lidija Čuček, Julija Volmajer Valh, 2024, original scientific article Abstract: Plastics play a crucial role in our daily lives. The challenge, however, is that they become waste and contribute to a global environmental problem, increasing concerns about pollution and the urgent need to protect the environment. The accumulation and fragmentation of plastic waste, especially micro- and nanoplastics in aquatic systems, poses a significant threat to ecosystems and human health. In this study, the decomposition and fragmentation processes of conventional and biobased plastic waste in simulated water bodies (waters with different pH values) and in real water systems (tap water and seawater) are investigated over a period of one and six months. Three types of plastic were examined: thermoplastic polyethylene terephthalate and thermoset melamine etherified resin in the form of nonwovens and biobased polylactic acid (PLA) in the form of foils. Such a comprehensive study involving these three types of plastics and the methodology for tracking degradation in water bodies has not been conducted before, which underlines the novelty of the present work. After aging of the plastics, both the solid fraction and the leachate in the liquid phase were carefully examined. The parameters studied include mass loss, structural changes and alterations in functional groups observed in the aged plastics. Post-exposure assessment of the fragmented pieces includes quantification of the microplastic, microscopic observations and confirmation of composition by in situ Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy. The leachate analysis includes pH, conductivity, turbidity, total carbon and microplastic size distribution. The results highlight the importance of plastic waste morphology and the minor degradation of biobased PLA and show that microfibers contribute to increased fragmentation in all aquatic systems and leave a significant ecological footprint. This study underlines the crucial importance of post-consumer plastic waste management and provides valuable insights into strategies for environmental protection. It also addresses the pressing issue of plastic pollution and provides evidence-based measures to mitigate its environmental impact.
Keywords: polylactic acid, polyethylene terephthalate fabric, melamine etherifed resin fabric, aquatic environment, fragmentation, waste disposal
Published in DKUM: 09.09.2024; Views: 73; Downloads: 20
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3. Assessing energy potential and chemical composition of food waste thermodynamic conversion products: a literature reviewAndreja Škorjanc, Darko Goričanec, Danijela Urbancl, 2024, original scientific article Abstract: This study examines the considerable volume of food waste generated annually in Slovenia, which amounted to over 143,000 tons in 2020. The analysis shows that 40% of food waste consists of edible parts, highlighting the potential for reduction through increased consumer awareness and attitudes towards food consumption. The study shows that the consumption phase contributes the most to waste food (46%), followed by primary production (25%) and processing/manufacture (24%). The study addresses various thermodynamic processes, in particular, thermal conversion methods, such as torrefaction pyrolysis and hydrothermal carbonization, which optimize energy potential by reducing the atomic ratio (H/C) and (O/C), thereby increasing calorific value and facilitating the production of solid fuels. The main results show the effectiveness of torrefaction, pyrolysis and hydrothermal carbonization (HTC) in increasing the energy potential of food waste.
Keywords: energy, thermodynamic conversions, pyrolysis, torrefaction, hydrothermal carbonization, food waste, energy potential, chemical composition
Published in DKUM: 28.08.2024; Views: 53; Downloads: 6
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4. A waste separation system based on sensor technology and deep learning: a simple approach applied to a case study of plastic packaging wasteRok Pučnik, Monika Dokl, Yee Van Fan, Annamaria Vujanović, Zorka Novak-Pintarič, Kathleen B. Aviso, Raymond R. Tan, Bojan Pahor, Zdravko Kravanja, Lidija Čuček, 2024, original scientific article Keywords: waste management, smart waste bin system, central post-sorting, sensor technology, deep learning, convolutional neural networks
Published in DKUM: 23.08.2024; Views: 51; Downloads: 8
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5. Degradation of waste tetra pak packaging with hydrothermal treatment in sub-/supercritical waterMihael Irgolič, Maja Čolnik, Petra Kotnik, Mojca Škerget, 2024, original scientific article Keywords: hydrothermal degradation, waste packing, tetra pak, subcritical water, subcritical waste, chemical recycling, one-stage process, two-stage process, product analysis
Published in DKUM: 16.07.2024; Views: 88; Downloads: 11
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6. The ǂeffect of fuel quality on cavitation phenomena in common-rail diesel injector—a numerical studyLuka Kevorkijan, Ignacijo Biluš, Eloisa Torres Jiménez, Luka Lešnik, 2024, original scientific article Abstract: Plastic is one of the most widely used materials worldwide. The problem with plastic
arises when it becomes waste, which needs to be treated. One option is to transform plastic waste
into synthetic fuels, which can be used as replacements or additives for conventional fossil fuels
and can contribute to more sustainable plastic waste treatment compared with landfilling and other
traditional waste management processes. Thermal and catalytic pyrolysis are common processes
in which synthetic fuels can be produced from plastic waste. The properties of pyrolytic oil are
similar to those of fossil fuels, but different additives and plastic stabilizers can affect the quality
of these synthetic fuels. The quality of fuels and the permissible particle sizes and number density
are regulated by fuel standards. Particle size in fuels is also regulated by fuel filters in vehicles,
which are usually designed to capture particles larger than 4 µm. Problems can arise with the
number density (quantity) of particles in synthetic fuels compared to that in fossil fuels. The present
work is a numerical study of how particle size and number density (quantity) influence cavitation
phenomena and cavitation erosion (abrasion) in common-rail diesel injectors. The results provide
more information on whether pyrolysis oil (synthetic fuel) from plastic waste can be used as a
substitute for fossil fuels and whether their use can contribute to more sustainable plastic waste
treatments. The results indicate that the particle size and number density slightly influence cavitation
phenomena in diesel injectors and significantly influence abrasion.
Keywords: plastic waste, synthetic fuels, pyrolytic oil, common rail, cavitation, erosion, particles
Published in DKUM: 05.07.2024; Views: 131; Downloads: 14
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7. The Thermochemical Conversion of Municipal Solid Waste by Torrefaction ProcessMaja 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: 255; Downloads: 19
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8. Professional qualifications recognition of doctors in the EU : a perspective of EU citizens and third-country nationalsŽiva Šuta, Karmen Pišek Šuta, 2023, original scientific article Abstract: This article explores the applicable rules in the context of professional qualifications recognition of doctors in the EU. In the pursuit of this examination, it focuses on two groups of individuals, namely EU citizens and third-country nationals, and differentiates between qualifications obtained in the EU and qualifications obtained outside EU. While EU citizens are generally free to pursue their medical profession in any EU Member State, third-country nationals experience difficulties in the recognition of their professional qualifications as they fall outside the scope of specific rules on professional qualifications recognition and do not enjoy free movement rights. The assessment of the applicable rules is followed by a conclusion that the EU citizens are protected under the EU legal framework for the recognition of professional qualifications, however, the legal framework for the recognition of foreign professional qualifications is still absent and depends largely upon general rules applicable to third-country nationals willing to settle and work in the EU.
Keywords: professional qualifications, mutual recognition, freedom of establishment, brain waste, doctors
Published in DKUM: 19.04.2024; Views: 258; Downloads: 23
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9. Thermal treatment of raw and pre-treated wastes from the paper industryAleksandra Petrovič, Christoph Hochenauer, Matej Zazijal, Lidija Čuček, Darko Goričanec, Danijela Urbancl, 2023, original scientific article Abstract: In this study, the thermal treatment of two types of waste from the paper industry was investigated, paper mill sludge and sewage sludge from biological wastewater treatment plants. Hydrothermal carbonisation (HTC) and torrefaction were investigated as sustainable alternatives for solid biofuel production. Untreated samples and samples chemically pre-treated with alcoholic vinegar were subjected to torrefaction at 350 °C in N2 atmosphere, and the exhaust gases were analysed. HTC was performed at 250 °C with a residence time of 4 h. The feedstocks and the biochars produced were characterised by different analytical methods, and the effects of pre-treatment on fuel properties were studied. Both processes, HTC and torrefaction, showed inspiring results in the production of biofuels from paper industry wastes under the tested experimental conditions. A positive influence of pre-treatment on fuel properties (higher heating value, carbon content) of the obtained char was observed, and changes in the gas phase during torrefaction were observed.
Keywords: thermal treatment of waste, wastewater treatment, hydrothermal carbonisation
Published in DKUM: 18.04.2024; Views: 237; Downloads: 8
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10. An innovative approach to organizational changes for sustainable processes : a case study on waste minimizationEva Krhač Andrašec, Tomaž Kern, Benjamin Urh, 2023, original scientific article Abstract: It is necessary to adapt constantly to the business environment with its changing demands. Understanding the objectives, scope, and limitations of actual process changes is crucial, and can be achieved with numerous measures, methods, and techniques. This research demonstrates an innovative approach to organizational changes to enable sustainable processes. In the first part of this research, relevant measures, methods, and techniques are selected through an in-depth literature review. Then, an international online questionnaire is executed among 213 enterprises from four countries. In the last part of this research, the developed approach is tested for the example of waste minimization in the process of developing coatings. Based on the analysis of the survey questionnaire, the usability and benefits of various measures are demonstrated, namely from the point of view of their positive impact on structural and operational efficiency indicators. At the end of the article, a case study presents the success of the innovative approach in terms of 88% waste minimization and up to 48% time and cost reductions in the process of developing coatings. The proposed approach enables better choices to be made and the more efficient use of various measures, which can lead to more sustainable processes and improve the efficiency of enterprises.
Keywords: organizational changes, key performance indicators, measures, methods and techniques, sustainable processes, waste minimization
Published in DKUM: 02.04.2024; Views: 286; Downloads: 23
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