1. Zero-waste strategy of small wastewater treatment plants with integrated thermal treatment of generated solid wastesDanijela Urbancl, Christoph Hochenauer, Angelika Michaela Zachl, Nika Fekonja, Aleksandra Petrovič, Darko Goričanec, Marjana Simonič, 2025, original scientific article Abstract: The aim of the study was to analyse two small wastewater treatment plants (SWTPs) and compare their treatment performance with the aim of developing a zero-waste strategy. The analyses showed that the second wastewater treatment plant had a problem with an increased phosphorus concentration in the wastewater as well as fluctuations in nitrogen removal. One of the key aspects was the recovery of phosphorus in the form of struvite precipitated on zeolite, which can be used as a fertiliser due to its significant nutrient content. The main benefit of the same SWTP is the separate collection of cellulosic material (labelled as sample RS), which has the potential for reuse as biochar, while from the first SWTP the sludge sample (labelled as sample SS) was taken and torrefied for comparison with RS. Both samples were torrefied at 250 ◦C and 350 ◦C in nitrogen and carbon dioxide atmospheres. The RS products obtained in CO2 atmosphere at 350 ◦C showed the best biochar properties, as they had a higher heating value (HHV) and a higher C content. Elemental analysis showed that the carbon content in RS and SS increased from 43 to 65 % and from 35 to 39 %, respectively. Measurement of the HHV of the torrefied RS product showed an increase from 17 to 26 MJ/kg, while for SS it increased from 15 to 17 MJ/kg. The comprehensive combustion index and the EMCI index show higher values for the RS samples torrefied at 350 ◦C. The H/C and O/C ratios are favourable for these samples, as the high quality of torrefied biomass is associated with the highest prices on the market. According to the TGA and FTIR analysis, the type of torrefaction atmosphere, in contrast to the torrefaction temperature, has little influence on the subsequent use of the torrefied samples in combustion. The results show that the integration of torrefaction for biochar production with phosphorus recovery by struvite precipitation is an efficient solution for waste management in small wastewater treatment plants.
Keywords: wastewater treatment plant efficiency, torrefication, N2 atmosphere, CO2 atmosphere, solid biofuels, proximate and ultimate analyses, thermogravimetry
Published in DKUM: 29.10.2025; Views: 0; Downloads: 7
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2. Supply chain integrity : addressing ethical concerns in agricultural supply chainsPaul Mukucha, Thulani Dube, Divaries Cosmas Jaravaza, 2025, original scientific article Abstract: Ethics has become a trending phenomenon in most disciplines as a result of the sustainability wave enshrined in the United Nations Sustainability Goals (SDGs). In business circles procurement ethics have become topical as a result of the rising malpractices whose ripple effects have far reaching economic, social and environmental consequences. In the agricultural supply chains procurement ethics have been called to question due to outcries from the tobacco contract farmers whose livelihoods are affected by supplier development washing in the form of exorbitantly priced contract farming inputs. The unethical practice of supplier development washing in the form of exorbitantly priced tobacco contract farming inputs has some ripple effects which this study sought to determine. Twenty-five contracted tobacco farmers were interviewed and the results indicated that farmers subjected to tobacco merchants’ unethical conduct tend to practice contractor switching, side marketing, become insolvent, and indulge in unorthodox cost cutting measures. The study recommended that the regulatory authorities should intervene to bring sanity to the tobacco supply chains through enforcing contract farming mechanisms that reflect genuine supplier development.
Keywords: information and communication technology, supply chain efficiency, SMEs and material requirement planning
Published in DKUM: 28.10.2025; Views: 0; Downloads: 1
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3. Strategic integration of sustainability, circular economy, and blockchain in Slovenian urban governanceGorazd Justinek, 2025, original scientific article Abstract: Slovenia has 12 urban municipalities, each with a sustainable development strategy aligned with the Agenda 2030 framework and valid through 2030. This paper examines how these strategies incorporate emerging technologies, particularly blockchain, and innovative sustainability concepts such as the circular economy. Achieving the goals of Agenda 2030, especially transitioning to a circular economy, requires doubling energy efficiency by 2030. While blockchain and the circular economy have often been studied separately, this research explores their intersection within the context of urban sustainability. The study applies qualitative content analysis to the official development strategies of all 12 urban municipalities. This analysis is complemented by semi-structured interviews with senior officials from the Ministry of the Environment, Climate and Energy, and the Vice Mayor of Ljubljana, providing institutional perspectives on strategic priorities and implementation logic. This is the first comprehensive analysis of how Slovenian urban municipalities address the interconnected themes of sustainability, circular economy, and blockchain technology. The findings contribute to academic discussions and offer practical recommendations to enhance innovation in urban sustainability planning
Keywords: blockchain, circular economy, energy efficiency, Agenda 2030, urban municipality
Published in DKUM: 02.10.2025; Views: 0; Downloads: 5
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4. Open-source transformer-based information retrieval system for energy efficient robotics related literatureTine Bertoncel, 2025, original scientific article Abstract: Background and Purpose: This article employs the Hugging Face keyphrase-extraction-kbir-inspec machine learning model to analyze 654 abstracts on the topic of energy efficiency in systems and control, computer science and robotics. Methods: This study targeted specific arXiv categories related to energy efficiency, scraping and processing ab - stracts with a state-of-the-art Transformer-based Hugging Face AI model to extract keyphrases, thereby enabling the creation of related keyphrase networks and the retrieval of relevant scientific preprints. Results: The results demonstrate that state-of-the-art open-source machine learning models can extract valuable information from unstructured data, revealing prominent topics in the evolving field of energy-efficiency. Conclusion: This showcases the current landscape and highlights the capability of such information systems to pinpoint both well researched and less researched areas, potentially serving as an information retrieval system or early warning system for emerging technologies that promote environmental sustainability and cost efficiency.
Keywords: energy efficiency, keyphase extraction, early warning system, information system, semantic network, transformer models, industry 4.0
Published in DKUM: 07.08.2025; Views: 0; Downloads: 3
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5. Motor efficiency in relation to body weight status and gender in preschool childrenMiran Muhič, 2024, original scientific article Abstract: Deficits in motor skills and function are associated with overweight and obesity in children. This study aimed to investigate the development of motor efficiency in 3-4-year-old children over seven months and to identify possible gender and body weight status differences in motor efficiency. In the study, there were 45 children (21 girls, 24 boys), the mean age of whom was 39 months. Analysis of the results of testing for differences in motor efficiency according to body weight status and movement components showed no statistically significant differences (p>0.05) between healthy weight and overweight children.
Keywords: motor efficiency, motor abilities, body weight status, preschool children
Published in DKUM: 29.07.2025; Views: 0; Downloads: 8
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6. Can we have both? The challenges of efficiency outcomes in a public procurement system and reaching the strategic goals of procurementSašo Matas, Žan Oplotnik, Timotej Jagrič, 2025, original scientific article Abstract: This article explores the cost efficiency of public procurement procedures, techniques and strategic policies. Member States in the EU spend large sums of money on the procurement of various items, yet public procurement in the EU struggles with issues of competitiveness, efficiency and overlapping goals. The competitiveness and efficiency of various factors, procedures, techniques and sustainable measures employed in public procurement procedures that influence cost efficiency were examined in this study using data from Slovenian public procurement over the past eight years. The analysis employed a binary logit model that facilitates the efficient utilization of public funds and predicts substantial price reductions in public procurement procedures. The findings underscore the significance of transparency and open markets. The optimal cost-efficiency outcomes are achieved through combinations of transparent procedures and an undisclosed market environment during the tendering phase, complemented by less binding secondary procurement objectives. Conversely, procurement techniques that tend to disclose more information about competitors in the procurement process are found to be less cost-effective. Non-mandatory sustainable policies in public procurement tend to lead to better results in terms of cost efficiency than those imposed by an obligatory legal framework.
Keywords: public procurement, efficiency, strategic procurement, sustainable measures
Published in DKUM: 09.07.2025; Views: 0; Downloads: 9
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7. Achieving maximum smart readiness indicator scores: a financial analysis with an in-depth feasibility study in non-ideal market conditionsMitja Beras, Krzysztof Stępień, Miha Kovačič, Uroš Župerl, 2025, original scientific article Abstract: For European competitiveness, energy efficiency must be increased. An important part of energy efficiency depends on an efficient building stock—the sector with the greatest potential for energy savings, as more than a third of all primary energy is consumed in buildings. A new instrument, the smart readiness indicator (SRI), is being prepared to accelerate the implementation of smart solutions in buildings and establish a market that would require and accelerate the implementation of such solutions. In this paper, we examine how the SRI score of a shopping center (with an already relatively advanced automation system) changes if we perform an energy optimization worth approximately 6.6 million EUR. As all the upgrades suggested by the SRI methodology cannot be implemented, this paper is the first of its kind to define the maximum feasible SRI score. The necessary measures are elaborated comprehensively, analyzed, and evaluated both technically and financially (IRR, ROI, and payback time). This type of approach is suitable for less developed EU markets without smart grids, DSM, and predictive functions.
Keywords: smart systems readiness indicator (SRI), methodology, smart systems, real estate energy renovations, energy efficiency, financial analysis, smartness
Published in DKUM: 02.07.2025; Views: 0; Downloads: 8
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8. Evaluating middle-distance passenger transportation : a comparison of the time efficiency, sustainability, and break-even distances between high-speed-rail and air travel in SwedenMartin Fale, Tomaž Kramberger, Bojan Rupnik, Shen Lixin, Tea Vizinger, 2025, original scientific article Abstract: Debate regarding the use of airplanes or high-speed trains in middle-distance passenger transportation has evolved into a strong field of research. With the aim to mitigate the environmental footprint of air travel, the European Union’s initiatives are focused on redirecting passengers from airplanes to high-speed trains. This shift is hampered by significant variations in train accessibility across Europe. Using Sweden as an example, we tested the break-even distance and evaluated the findings from both a time-efficiency perspective and a sustainability perspective. Airplanes hold the upper hand on high-speed trains in middle-distance passenger transportation from the time perspective. This perspective provides us with a clear answer, but if we consider the sustainability perspective, it may affect the results. The results indicate that the presented proof of concept makes sense and can be easily adapted to any decision-making process regarding the choice of the preferable transportation mode, although the procedure is extremely time consuming. For policymakers, this proof of concept can represent a priceless tool because the resulting figures carry valuable information about (under)developed and (less-)integrated transportation modes in commuting and transportation systems.
Keywords: time efficiency, sustainability, breakeven distance, high-speed-rail (HSR) travel, air travel
Published in DKUM: 01.07.2025; Views: 0; Downloads: 2
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9. Children with reduced cognitive efficiency and addition of natural numbers up to 20 : a case studyIrena Budínová, Tomáš Janík, 2021, original scientific article Abstract: The study deals with teaching and learning the addition of natural numbers up to 20 in the first two years of primary school. The first part presents the theoretical background for addition of natural numbers, the procedural and conceptual approach to addition, and the theory of the additive triad. The causes of the difficulties some children have with the field of the addition of natural numbers are outlined, and the issue of reduced cognitive efficiency is briefly introduced as one of the causes. The second part of the study presents a case study of a girl (7 years old) who experienced difficulty in learning addition. The approaches to and results of remedial tutoring completed by the girl are described. In the discussion, the issue of the addition of natural numbers is incorporated into a broader pedagogical context.
Keywords: learning addition, pupils with learning difficulties in mathematics, cognitive efficiency, natural numbers, additive triad, case study
Published in DKUM: 27.06.2025; Views: 0; Downloads: 6
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10. Artificial intelligence - based exergy analysis of an absorption cooling systemDušan Strušnik, 2025, original scientific article Abstract: An artificial intelligence (AI)-based exergy analysis of an absorption cooling system (ACS), utilizing a lithium bromide–water refrigeration cycle, is presented in this paper. The ACS is characterised by the utilisation of the intermediate-pressure (IP) extraction steam from the steam turbine for its operation. The exergy analysis of the ACS is detailed, based on AI modelling through a machine learning algorithm, which predicts and optimises the ACS performance. The machine learning algorithm is validated using real process data obtained through ACS measurements via the supervisory control and data acquisition (SCADA) system. The AI results show that the ACS generates 126.71 kW of cooling for district cooling and 279.57 kW of heat, which is used for heating demineralised water. During the analysis period, the ACS consumed an average of 152.86 kW of IP steam, and operated with an average exergy efficiency of 17.3%. The study suggests that the average exergy efficiency of the ACS could be improved by using lower-quality steam, or even hot water, for operation.
Keywords: absorption, analysis, artificial intelligence, cooling, efficiency, exergy
Published in DKUM: 16.06.2025; Views: 0; Downloads: 5
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