Uticaj kadmijuma na klijanje semena i rast pšenice

In this study, the effect of Cd on the germination, growth of seedlings and composition of plants deriving from contaminated grains, grown in the field, was examined. Wheat grains were soaked in Cd-containing solutions: 0 (control, deionized water), 10-5 , 10-4 , 10-3 , and 10-2 M CdCl 2 during 24h. One portion of grains was used to test germination and seedling growth, while the other was sown in the field. The concentration of Cd in the grains almost linearly increased with the increase in the applied concentrations of Cd, which reduced the germination and energy of germination and increased the proportion of atypical seedlings. Larger concentrations of Cd significantly impaired the growth of seedlings (length of the shoots and roots, dry matter mass). In the grains of the field-grown plants the concentrations of N, P, and K were not affected by Cd, but their concentrations in the straw declined (especially of N). These results suggest that the emergence and development of plants on the soil polluted by Cd are likely to be significantly limited and yield reduced.Kadmijum (Cd) je potencijalni zagađivač sredine živih organizama i pri većim koncentracijama odlikuje se jakim fitotoksičnim dejstvom. U radu je u laboratorijskim uslovima proučeno dejstvo različitih koncentracija kadmijuma na klijanje i rast mladih biljaka pšenice, a u poljskim uslovima njegov uticaj na koncentraciju mineralnih materija u zrnu i slami u fazi pune zrelosti biljaka, koje su potekle od zrna tretiranog kadmijumom. S povećanjem koncentracije kadmijuma u fazi bubrenja semena skoro se linerano povećala njegova koncentracija u semenu. Utvrđeno je da veće koncentracije kadmijuma značajno smanjuje klijanje i energiju klijanja semena, a povećavaju učešće atipičnih klijanaca i neproklijalog semena. Veće koncentracije kadmijuma značajno su smanjile rast mladih biljaka kao i masu njihove suve materije. Rast nadzemnog dela i korena smanjen je u većoj meri od mase suve materije, na osnovu čega se može zaključiti da je kadmijum u većoj meri uticao na faktore rasta nego na stvaranje suve mase. Najveća primenjena koncentracija kadmijuma smanjila je hidratisanost 68 nadzemnog dela mladih biljaka. Bubrenje semena u prisustvu različitih koncentracije kadmijuma nije uticalo na koncentraciju azota, fosfora i kalijuma u zrnu, a smanjilo je njihovo prisustvo u slami, naročito azota na kraju vegetacije. Dobijeni rezultati potvrđuju nalaze ranijih istraživanja kod drugih biljnih vrsta na osnovu kojih su fiziološki i biohemijski procesi klijanja semena značajno inhibirani u prisustvu većih koncentracija kadmijuma. Na osnovu navedenog može se predvideti da će na zemljištu zagađenom kadmijumom nicanje useva i rast mladih biljaka pšenice biti ograničeno, što će se nepovoljno odraziti na prinos useva

Energy Management Model for Sustainable Development in Hotels within WB6

The aim of this paper is to propose a model for an energy management system (EnMS) in the hospitality industry in line with the ISO 50001 standard. The new proposed model, specifically developed for service organizations, was based on the Plan–Do–Check–Act cycle and was confirmed in 280 hotels in the Western Balkans 6 (WB6) region. The data were used to investigate if hotel properties represent an influential factor in the wider implementation of EnMS requirements. The proposed model, based on the ISO 50001 standard, was developed into sub-categories, including actual regulations and legislation within the EU and WB6. Hotels, as some of the most energy-demanding buildings, due to their purpose and processes, should provide their guests with electricity, hot water, heating and air-conditioning every hour of every day. The survey was conducted in 280 hotels and lasted from December 2021 to September 2022. The research shows that the average implementation of EnMS requirements was 38.07% for the whole researched sample, i.e., 25.86% in Albania, 30.40% in Bosnia and Herzegovina, 26.11% in Kosovo, 46.34% in Montenegro, 29.86% in North Macedonia and 44.56% in Serbia. In the researched case study, the average implementation of the PLAN phase (phase for establishing basics for energy management) was 35.71%, implementation of the DO phase (phase for implementing energy management processes) was 44.90%, implementation of the CHECK phase (phase for monitoring and the measurement of energy performance) was 45.45%, and finally, implementation of the ACT phase (phase for reviewing and improving energy management) was only 25.36%. The proposed model is significant as it can be used for broader research to investigate other business sectors in hospitality and for policymakers to propose energy consumption strategies and measures for energy savings that would have a minimal impact on service quality. The novelty of this research can be seen not only in the specifically developed model for service organizations in the hospitality sector but it also contains current data from the verified model in one specific region which offers the possibility of benchmarking and evaluating one’s own organization

Energy Management Model for Sustainable Development in Hotels within WB6

The aim of this paper is to propose a model for an energy management system (EnMS) in the hospitality industry in line with the ISO 50001 standard. The new proposed model, specifically developed for service organizations, was based on the Plan–Do–Check–Act cycle and was confirmed in 280 hotels in the Western Balkans 6 (WB6) region. The data were used to investigate if hotel properties represent an influential factor in the wider implementation of EnMS requirements. The proposed model, based on the ISO 50001 standard, was developed into sub-categories, including actual regulations and legislation within the EU and WB6. Hotels, as some of the most energy-demanding buildings, due to their purpose and processes, should provide their guests with electricity, hot water, heating and air-conditioning every hour of every day. The survey was conducted in 280 hotels and lasted from December 2021 to September 2022. The research shows that the average implementation of EnMS requirements was 38.07% for the whole researched sample, i.e., 25.86% in Albania, 30.40% in Bosnia and Herzegovina, 26.11% in Kosovo, 46.34% in Montenegro, 29.86% in North Macedonia and 44.56% in Serbia. In the researched case study, the average implementation of the PLAN phase (phase for establishing basics for energy management) was 35.71%, implementation of the DO phase (phase for implementing energy management processes) was 44.90%, implementation of the CHECK phase (phase for monitoring and the measurement of energy performance) was 45.45%, and finally, implementation of the ACT phase (phase for reviewing and improving energy management) was only 25.36%. The proposed model is significant as it can be used for broader research to investigate other business sectors in hospitality and for policymakers to propose energy consumption strategies and measures for energy savings that would have a minimal impact on service quality. The novelty of this research can be seen not only in the specifically developed model for service organizations in the hospitality sector but it also contains current data from the verified model in one specific region which offers the possibility of benchmarking and evaluating one’s own organization

"It happened, what’s the problem?" and "A guide through the problem": A model for consideration of ecological issues in chemistry education

In order to improve the ability for application of knowledge of chemistry (acquired in the existing educational system) in real life the Model for Consideration of Ecological Issues was developed and applied in high school. The Model consists of the continuous text (“It Happened, What’s the Problem?”) and the test with non-continuous text (“A Guide Through the Problem”), which are prepared for consideration of the problem of eutrophication. All results obtained (average achievement of 70.9±14.3 %) showed that the application of the Model enabled: understanding of an ecological problem based on scientific representations of the term eutrophication given in the continuous text, realization that the pollution of our environment may be directly related to modern life, application of acquired knowledge of chemistry to observe and understand the cause and effect of eutrophication in our environment, to draw a scientific conclusion, and understanding the importance of science and technology discoveries for solving ecological problems. In addition, Model contributed to the development of student’s environmental literacy (ecological knowledge and cognitive skills), ability to think critically, and provided possibilities for classroom knowledge to become applicable in real life. [Projekat Ministarstva nauke Republike Srbije, br. 179048

Techno-economic optimization of configuration and capacity of a polygeneration system for the energy demands of a public swimming pool building

A polygeneration system is an energy system capable of providing multiple energy outputs to meet local demands, by application of high process integration. In this paper, optimal configuration and capacity of a polygeneration system for an indoor swimming pool building is determined by application of a method based on TRNSYS simulation and GenOpt optimization software. Based on the applicability, a superstructure of the polygeneration system is integrated, consisting of the following polygeneration modules: an internal combustion engine cogeneration module, a vapor compression chiller, and adsorption chiller, a ground source heat pump, flat plate solar thermal collectors, photovoltaic collectors, and heat storage. Annual behavior of energy loads of the public swimming pool building during a typical meteorological year and the polygeneration system are modeled and simulated using TRNSYS software, whereas techno-economic optimization is performed by GenOpt optimization. The results indicated the optimal con-figuration of the polygeneration system for the modelled energy demands, as well as the optimal capacity of the polygeneration modules, thus defining the optimal capacity of the polygeneration system for the energy demands of the public swimming pool building. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 42006: Research and development of energy and environmentally highly effective polygeneration systems based on using renewable energy sources

Construction optimization of hot water fire-tube boiler using thermomechanical finite element analysis

Exploitation experience of hot water boiler plants indicates relatively frequent and permanent breakdowns resulting from the accident state of various elements of the boiler. In addition to the damages caused by the corrosion processes and inadequate management of the plant, the phenomena of fatigue of boiler elements exposed to high pressures and temperatures can occur. Due to high pressure and temperature certain boiler elements are exposed to, high strain and stress of these elements can eventually lead to breakdowns. In this paper, a hot water fire tube boiler, produced by “Minel-Kotlogradnja” Belgrade, type TE110V, installed within the plant “Technical Faculties” at Faculty of Mechanical Engineering in Nis, Serbia, is analyzed. Thermomechanical stress-strain analysis is performed with loads typically occurring during operation. Finite element analysis is performed using ANSYS Workbench 17 Software package, while the CAD model is formed using SOLID WORKS 2015. The results were used to investigate and to give recommendations for the thickness of tube plate of the first reversing chamber based on determined functional dependence of equivalent stress in the tube plate from the thickness of the plate. The noted functional dependence was determined by Kriging response surface based on results of virtual numerical experiment with different thicknesses of the tube plate

Solidification/stabilization of metal polluted sediment of Krivaja river

The Krivaja River is the longest natural water body (109 km) that flows completely within the borders of Serbian province of Vojvodina. In the absence of national legislation, the sediment quality was assessed in accordance with the Dutch classification methodology. It was found that the river sediment is highly contaminated with copper and zinc (192 mg kg-1 and 1218 mg kg-1 respectively), and as such is an extreme risk to the environment and human health. The solidification/stabilization (S/S) treatment with local clay, that has high capacity of cation exchange 70.2 meq/100 g and specific surface area of 630 m2 g-1, was employed for remediation of the contaminated sediment. The sequential extraction procedure showed that the copper and zinc have medium risk for the environment, with the percentage in the carbonate fraction of 18 and 22% respectively. The results of sequential extraction are not in full agreement with the results of pseudo-total metal concentration in the sediment, which only confirms that the total metal concentration is not sufficient to define the real danger to the environment. Based on the pseudo-total metals concentration, the sediment is of Class 4 (Dutch standards). However, judging from the results of sequential extraction, the metals show medium risk. Obviously, these results have to be taken into account in the assessment of the sediment quality, remediation procedures and sediment disposal in general. After the treatment, the proportion of these two metals in the first fraction is significantly reduced (Cu less than 2%, Zn 10%) in most of samples. In order to determine the long-term behavior of S/S mixtures, leaching tests were conducted in accordance with semi-dynamic ANS diffusion test for 90 days. The results indicated that clay can effectively immobilize Cu and Zn: the cumulative leached fraction of copper in mixtures with clay was in the range from 0.001% (mixture with 80% clay) to 0.15% (mixture with 10% clay), and the cumulative leached fraction of zinc in the range of 0.06% (mixture with 80% clay) to 0.10% (mixture with 10% clay). The diffusion coefficients, ranging from 1.5×10-12 cm2s-1 to 3.7×10-14 cm2s-1, showed an effective immobilization of both metals which suggests that these metals are practically immobilized in S/S mixtures even if the level of clay is low. From the point of LX values, all S/S mixtures can be used for the controlled utilization, because the leaching indices ranged from 11.8 to 13.4 for both metals. In all clay and sediment mixtures the dominant leaching mechanism is diffusion (slope values of 0.35 to 0.60), which once again confirms the effectiveness of the applied treatment and can be expected that only a very small amount of contaminants would leach into the environment over time. Future research is heading in the direction of troubleshooting the accumulation of used natural adsorbent after treatment, the possibility of permanent disposal, its regeneration or the possibility of its application as construction material