Globalization and industrialization have significantly impacted the dynamics of waste generation, management, collection, and processing, resulting in increasing amounts of various types of waste and serious environmental challenges. This paper analyzes the treatment and recycling of construction waste through the legislative framework and presents key challenges in the implementation of green policies in the Republic of Croatia. The methodological framework is based on a qualitative analysis of normative acts at the national level. Through statistical analysis and a detailed review of the waste categorization process, including the origin, type, and properties of waste, as well as statistical data on the produced, collected, and utilized amounts of construction waste in 2022, an insight into the current state of the construction waste management sector is provided. The example of the company “Reciklaža Mišić” demonstrates how recovered construction waste can lose its waste status and be used as recycled aggregate if the assessment and verification of the constancy of performance are carried out according to the technical specification aligned with the legal regulations governing construction products. The research results indicate the need for further familiarization of the construction sector with the procedure for removing waste status so that recycled aggregates can become a construction product and ensure market placement of materials, thereby contributing to the circular economy and reducing environmental burden. In conclusion, the research shows that achieving sustainable construction waste management requires further strengthening of the economic sector, better integration of ecological principles, and active involvement of the local community in the waste management process.
Hydrogen is a versatile energy carrier but its storing is challenging. For that reason, alternative hydrogen storage approaches are being intensively researched. Solid state storing of hydrogen in the form of ammines offers certain advantages, such as high storage capacity and relatively low toxicity. Therefore, in this work hexaammine complexes of nickel chloride and nickel bromide were prepared and investigated. Ni(NH3)6Cl2 and Ni(NH3)6Br2, were obtained by precipitation synthesis. The prepared complexes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The prepared particles are polydisperse, agglomerated and show a characteristic octahedral morphology. The samples consist solely of pure, well-crystalline, corresponding hexaamine complexes. Ni(NH3)6Br2 shows somewhat weaker nitrogen bonds with the central cation and weaker hydrogen bonds with halogen compared to Ni(NH3)6Cl2. Thermal analyses have shown that under the experimental conditions used, ammonia is released from Ni(NH3)6Cl2 in three stages, while in the case of Ni(NH3)6Br2, decomposition occurs in two stages. This difference is a consequence of the kinetic parameters of the desorption process. The maximum of the first stage of desorption occurs for the Ni(NH3)6Cl2 sample at a slightly lower temperature than for the Ni(NH3)6Br2 sample, which is attributed to thermodynamic factors.
Air quality monitoring has become essential for understanding the impact of pollutants on health and the environment. This paper explores the implementation of Arduino-based sensors in air quality monitoring, providing an affordable and effective solution for tracking pollutants such as PM2.5, NO2, and CO2. The system comprises interconnected components, including sensors for particulate matter, temperature, humidity, and volatile organic compounds, supported by real-time data visualization platforms like ThingSpeak. These sensors enable real-time data collection, analysis, and visualization, allowing users to identify pollution sources and make informed decisions for pollution reduction. The integration of IoT platforms enhances spatial resolution and accessibility of air quality data, offering valuable insights for personal, scientific, and regulatory applications. The study highlights the advantages of using cost-effective, portable sensors for improving environmental monitoring and supporting sustainable urban development.
Packaging is a huge problem in waste management, and food packaging stands out in particular. This article presents the results of preliminary research on the separation between aluminium and plastic from yogurt cup wastes as a sample of food packaging waste. Two different separation methods were used: eddy current and electrostatic separation. It has been shown that an eddy-current separator can be used for the separation of larger particles, where it is possible to obtain a concentrate with an aluminium content of 65.5% and recovery of 92.3%, while an electrostatic separator is more appropriate for the separation of finer particles, whereby a concentrate with an aluminium content can be obtained of 73.3% with recovery of 96.9%.
In the last decade, the Republic of Croatia has witnessed a continuous increase in municipal waste, but at the same time, there has been a steady rise in the rate of recovery and recycling. However, despite the positive trends, the set goals of waste management have still not been achieved dynamics of waste separation and processing. The City of Ludbreg, with almost 52 % of separately collected municipal waste, represents a successful model of sustainable and circular waste management, placing it among the only nine towns in the Republic of Croatia that have exceeded a 50 % rate of separately collected waste. This paper analyses the application of a circular waste management system in the City of Ludbreg and its role in achieving high recycling rates. Special emphasis is placed on the transformation of the local environment, including the elimination of illegal dumps and the creation of green spaces. The City of Ludbreg exemplifies how local communities can lead in circular economy practices by merging technological innovations with ecological awareness. Key success factors include education, local participation, and the integration of smart technologies in waste management. In conclusion, this research analyzes the challenges in separate waste collection and provides recommendations for further development and improvement of the waste management system at the local level, with the aim of achieving sustainable development goals. The result is the creation of an innovative and modern system that functionally integrates technology, infrastructure, and active participation of the local community, positioning the City of Ludbreg as an example of good and successful practice of a green and smart city.
