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Opis: Plastic waste is steadily polluting oceans and environments. Even when collected, it is still predominantly dumped or incinerated for energy recovery at the cost of CO2. However, no simple solution exists to deal with marine litter (ML). Overcoming limitations in collection, and in the environmentally, technically and economically acceptable use of the collected material, is of paramount importance. Chemical recycling can contribute to the transition towards a circular economy but the high variety and contamination of real waste remains the biggest challenge. In my research more than 100 kg of actual benthic ML from the North Adriatic Sea, including polyolefins packaging and polyamides fishing nets, were successfully processed “as-is” without pretreatment and converted into standardized marine gas oil (MGO) compliant with the ISO8217 via the pyrolysis and the distillation process; with 8 potential harmful emissions linked to the pyrolysis process monitored and curbed to safe levels. Approximately 45 wt% yield of raw pyrolysis oil (RPO) was obtained of which 50% (v/v) being MGO. RPO and its distillates were chemically characterized via GC-MS. For all samples, more than 30% of the detected compounds were identified. 2,4-dimethyl-1-heptene, a marker of PP pyrolysis, is the most represented peak in the chemical signature of all the marine litter samples, and it differentiates commercial and pyrolysis marine gasoil. Besides, I studied the detailed composition and the steam cracking performance of distilled pyrolysis oil fractions in the naphtha-range of ML and mixed municipal plastic waste (MPW) considered unsuitable for mechanical recycling. Advanced analytical techniques including comprehensive two-dimensional gas chromatography (GC × GC) coupled with various detectors and inductively coupled plasma – mass spectrometry (ICP-MS) was applied to characterize the feedstocks and to understand how their properties affect the steam cracking performance. Both waste-derived naphtha fractions were rich in olefins and aromatics (~70% in MPW naphtha and ~51% in ML naphtha) next to traces of nitrogen, oxygen, chlorine and metals. ICP-MS analyses showed that sodium, potassium, silicon and iron were the most crucial metals that should be removed in further upgrading steps. Steam cracking of the waste-derived naphtha fractions resulted in lower light olefin yields compared to fossil naphtha used as benchmark, due to secondary reactions of aromatics and olefins. Coke formation of ML naphtha was slightly increased compared to fossil naphtha (~50%), while that of MPW naphtha was more than ~180% higher. It was concluded that mild upgrading of the waste-derived naphtha fractions or dilution with fossil feedstocks is sufficient to provide feedstocks suitable for industrial steam cracking. Waste plastics oil (WPO) obtained from a relatively large-scale batch rotary kiln pyrolysis reactor was collected and stored for 60 months in dark at 10 °C, periodically thoroughly characterized and finally tested as the drop-in fuel in internal combustion engine. It was evaluated by investigation of combustion process and emission formation phenomena under a wide range of operating parameters. The results were compared with those obtained with diesel fuel at the same injection and gas path parameters to provide a comprehensive basis for further development of control strategies. Finally, the solid residue from the pyrolysis process was evaluated for material recovery or safe disposal, thus closing the mass balance of the whole process. Due to the great contamination of the original feedstock, stabilization of solid residue is required to attain not hazardous waste criteria, but once stabilized with Portland concrete, it could even be employed as construction material, therefore transforming a problem into an opportunity.
Ključne besede: marine litter, marine fuel, pyrolysis, circular economy, environmental impact, chemical recycling, steam-cracking, pyrolysis char
Objavljeno v RUNG: 12.05.2023; Ogledov: 1158; Prenosov: 20
Celotno besedilo (14,33 MB)

Ključne besede: dependence relation, degree of influence, degree of impact, fuzzy set, hypercompositional algebra
Objavljeno v RUNG: 10.08.2021; Ogledov: 1740; Prenosov: 49
Celotno besedilo (216,43 KB)

Ključne besede: hyperoperation, hypergroupoid, dependence relation, influence, impact
Objavljeno v RUNG: 24.09.2019; Ogledov: 2870; Prenosov: 141
Celotno besedilo (279,83 KB)

Opis: The need of wood for building and heating, the extensive grazing and population growth in the 18th and 19th centuries led to turning the Karst area in Slovenia into a bare land. In the 19th century organised reforestation started which was successfully performed with Black pine (Pinus nigra J. F. Arnold). Later on, the reforestation was replaced by the process of spontaneous afforestation. The successfulness of reforestation with Black pine also made it possible for the native tree species to grow. The abandoning of the use of agricultural land also contributes to the spontaneous afforestation. In this project we determined the changes in forest cover through time. We used aerial photographs from the years 1957, 1975, 1985 and 2015. By drawing polygons on the maps in the QGIS programme on the areas that are covered with forests, are overgrown or are used for agricultural purpose we compared the areas from the maps of different years. We found out that the area covered with forest had increased by more than 50 % from the year 1957 to 2015. The increase in the area of forest cover due to afforestation provides new habitats for fauna and flora to live in.
Ključne besede: Karst, afforestation, new habitat, Black pine, human impact
Objavljeno v RUNG: 07.11.2017; Ogledov: 4972; Prenosov: 0
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