Although thermal recovery of waste plastics is widely practiced in many European countries, reliable information on the amount of waste plastics in the feed of waste-to-energy plants is rare. In most cases the amount of plastics present in commingled waste, such as municipal solid waste, commercial, or industrial waste, is estimated based on a few waste sorting campaigns, which are of limited significance with regard to the characterisation of plastic flows. In the present study, an alternative approach, the so-called Balance Method, is used to determine the total amount of plastics thermally recovered in Austria’s waste incineration facilities in 2014. The results indicate that the plastics content in the waste feed may vary considerably among different plants but also over time. Monthly averages determined range between 8 and 26 wt% of waste plastics. The study reveals an average waste plastics content in the feed of Austria’s waste-to-energy plants of 16.5 wt%, which is considerably above findings from sorting campaigns conducted in Austria. In total, about 385 kt of waste plastics were thermally recovered in all Austrian waste-to-energy plants in 2014, which equals to 45 kg plastics cap^-1. In addition, the amount of plastics co-combusted in industrial plants yields a total thermal utilisation rate of 70 kg cap^-1 a^-1 for Austria. This is significantly above published rates, for example, in Germany reported rates for 2013 are in the range of only 40 kg of waste plastics combusted per capita.

Organic fertilizer use constitutes one of the main pathways through which (micro)-plastics enter the environment. However, little is known about the extent of plastic contamination in biowaste composts from Sub-Saharan Africa, where municipal biowaste collection involves minimal to no source separation. This study assessed macro- and microplastic contamination in composts from two Clean Development Mechanism composting facilities in Uganda processing mixed municipal solid waste for agricultural use. Finished composts were sampled per Plant at monthly intervals for four months (September 2023 to January 2024), and sieved into different size fractions: >5, 1.18-5, 0.6-1.18, 0.212-0.6, and 0.063-0.212 mm. Microplastics in each fraction (5 mm) in composts were analyzed. The results indicated heavy macro- and microplastic contamination in composts from both Plants. Macroplastics (>5 mm) ranged from 0.11 to 4.70 (1.50 ± 1.24) g/kg dry weight in Plant 1 and 0.36-4.93 (1.78 ± 1.27) g/kg dry weight in Plant 2. Total microplastics in composts exceeded all previous literature studies, averaging about 49,000 ± 7,000 and 62,000 ± 6,000 items/kg dry weight, respectively. For both facilities, compost fraction 0.212-0.6 mm showed the highest microplastic contamination, followed by 0.063-0.212, 0.6-1.18, and 1.18-5 mm. Total microplastics in composts depended on facility pile turning, feedstock contamination, and local population density. Polyethylene and polypropylene were the most dominant polymers in macro- and microplastics from composts, with fragments and fibers most dominant microplastic shapes. Estimations of plastic load show that such MSW compost can input into amended soils macroplastics of 2.0-106.7 kg/ha and 2.9×10⁸ - 2.4×10⁹ microplastic items/ha per recommended application.

Zusammenfassung Da brennbare Abfälle zumeist ein Gemisch aus biogenen (z. B. Papier, Holz, Küchenabfälle) und fossilen Materialien (Kunststoffe) darstellen, entstehen bei ihrer thermischen Verwertung sowohl klimaneutrale als auch klimarelevante CO₂-Emissionen. Analog verhält es sich auch bei der erzeugten Energie (Strom), die entsprechend dem jeweiligen Biomassegehalt des Abfalls zum Teil als erneuerbar eingestuft wird und als solche auch auszuweisen ist. Im Zuge der vorliegenden Studie wurden erstmals auf nationaler Basis die fossilen und biogenen Anteile in thermisch verwerteten Abfällen bestimmt. Die methodische Grundlage dabei bildet die von der Technischen Universität Wien auf europäischer Ebene patentierte Bilanzenmethode. Das Verfahren beruht auf einem mathematischen Abgleich von Materialdaten (z. B. mittlere stoffliche Zusammensetzung biogener und fossiler Materialen) mit messbaren Betriebsgrößen der Verbrennungsanlage (z. B. Reingasmenge, O₂- und CO₂-Konzentration im Reingas, Dampfmenge). Aufgrund einer Anlagenertüchtigung und teils fehlender CO₂-Messungen konnten 10 von 13 Abfallverbrennungsanlagen und damit rund 88 % des in österreichischen Müllverbrennungsanlagen verwerteten Abfalls für die Auswertung berücksichtigt werden (rund 2,3 Mio. Tonnen). Die Ergebnisse zeigen eine große Streuung der biogenen Heizwertanteile der Anlagen (im Jahresmittel stammen zwischen 35,7 ± 2,4 % und 61,2 ± 2,7 % der eingesetzten Energie aus biogenen Quellen). Auch eine starke zeitliche Variation der Abfallzusammensetzung auf Basis von Monatsmittelwerten ist deutlich erkennbar. Folglich lässt sich für Abfallverbrennungsanlagen kein allgemein gültiger Heizwertanteil oder Emissionsfaktor ableiten und eine anlagenspezifische Auswertung über einen längeren Zeitraum (wie es mit der Bilanzenmethode relativ einfach möglich ist) erscheint zielführend für eine zuverlässige Ausweisung des erneuerbaren Energieanteils oder der fossilen CO₂-Emissionen. Die eingesetzten Energien aus fossilen und biogenen Abfallbestandteilen (für die 10 betrachteten Anlagen) liegen im Jahr 2014 bei rund 11.450 ± 120 TJ und 10.730 ± 110 TJ. Es ergeben sich gesamt rund 1060 ± 24 kt klimarelevantes CO₂, das aus den thermischen Abfallverwertungsanlagen in Österreich im Jahr 2014 emittiert wurde (mit Hochrechnung auf alle 13 Anlagen).

This study examines public waste, meaning solid waste generated "on the go" in public spaces such as streets, parks and plazas. Despite containing a high proportion of recyclable materials, this waste stream is frequently overlooked in both academic research and circular waste management strategies. Using Vienna, Austria, as a case study, the research employs Material Flow Analysis (MFA) to systematically assess public waste flows and evaluate five alternative management scenarios. The scenarios include strategies such as enhanced source separation and advanced automated sorting of residual waste, aiming to enhance circular material use in public space. Waste flows were analyzed in detail across 16 sub-fractions, enabling a highly granular and accurate modelling approach. Although public waste represents only 4.5% of municipal solid household waste in Vienna, it contains a high proportion of recyclable materials (65%), much of which is currently not recovered due to a lack of waste separation (in the status quo less than 3% of recyclables are source-separated). Study results show that scenarios involving advanced residual waste sorting achieve the highest overall material recovery, where over 40% of publicly disposed waste is recovered for recycling. However, if additional factors like the quality of recovered materials are taken into account, the performance difference between separate collection and automated residual waste sorting is expected to diminish. This study provides the first detailed modelling of public waste flows and a robust foundation for evidence-based decision-making and future research on economic and environmental impacts.

This research explores the effects of milling on fecal sludge (FS) biochar with an emphasis on milling time (5, 10, and 15 min) and ball-to-powder ratio (BPR) (4.533 g/g, 9.067 g/g, and 10.5 g/g). FS biochar was prepared through slow co-pyrolysis of a 50:50 mixture (by weight) of fecal sludge and rice husk powder at 550 °C. The resultant FS biochar with good qualities was subjected to methylene blue (MB) dye adsorption at varying FS biochar weights (0.05 g, 0.1 g, and 0.15 g) and adsorption durations. The BSA peaked at 50 m²/g for a BPR of 10.5 g/g and a milling duration of 10 min. Prolonged milling (15 min) led to structural degradation and reduced BET surface area (BSA). The pore volume peaked at a BPR of 9.067 g/g for shorter milling times and 10.5 g/g for extended milling. The SEM revealed that a milling time of 10 min at a BPR of 9.067 g/g provided the best balance between particle size reduction and uniform morphology, minimizing agglomeration. MB adsorption revealed that FS biochar milled for 10 min and 9.067 g/g BPR demonstrated the best properties. These findings highlight the potential of FS biochar for applications in environmental remediation and agricultural fields, contributing to resource recovery from FS.