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Item type:Publication, Access status: with files , Decomposition of biodegradable plastic bags for kitchen waste collection in industrial compostingWith the growing awareness of microplastics in the environment, the question of microplastics as remnants of biodegradable plastic (BDP) products is gaining momentum. BDP bags for kitchen waste collection are often certified as fully compostable as proof of industrial compostability. Frequently certification is done using under standardized laboratory conditions within 12 weeks. Composting plants often process biowaste into compost in a shorter time under inhomogeneous conditions. This study investigates the decomposition behavior of commercially available BDP bags for kitchen waste collection at an industrial composting plant within a practically realistic time frame of 6 weeks. The research determines the decomposition behavior under practice conditions. Four bag types, two made from thermoplastic starch (TPS) blends and two from polylactic acid (PLA) blends underwent composting. The decomposition was evaluated by examining the remaining macro- (> 8 mm), meso- (2–8 mm), and microparticles (1–2 mm) in the compost with different methods. After 6 weeks, the mass-based decomposition rate of TPS blend bags exceeded 95%. In contrast, PLA blend bags failed to reach a decomposition rate of 90%. The study did not depict very small particles <1 mm. However, they are present. The study findings indicate that composting time and conditions, inhomogeneities, as well as the bag type are crucial factors influencing the decomposition of BDP bags. Concerns are raised about the usefulness of DIN 13432 as certification scheme for industrial conditions.Publicationtype: Journal Article59 108 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Hybrid leaching of tantalum and other valuable metals from tantalum capacitor waste(2023-04-03); ; ; ; We propose a novel integrated model for the recovery of tantalum from tantalum-rich waste using a combination of hydrometallurgical and bio-metallurgical processes. To this end, leaching experiments with heterotrophs (Pseudomonas putida, Bacillus subtilis and Penicillium simplicissimum) were carried out. The heterotrophic fungal strain leached manganese with an efficiency of 98%; however, no tantalum was detected in the leachate. An unidentified species did mobilise 16% tantalum in 28 days in an experiment with non-sterile tantalum capacitor scrap. Attempts to cultivate isolate and identify these species failed. The results of a range of leaching trials resulted in an effective strategy for Ta recovery. A bulk sample of homogenised Ta capacitor scrap was first subjected to microbial leaching using Penicillium simplicissimum, which solubilised manganese and base metals. The residue was subjected to the second leach using 4 M HNO3. This effectively solubilised silver and other impurities. The residue collected after the second leach was pure tantalum in concentrated form. The hybrid model produced derives from observations from previous independent studies and shows that we can effectively recover tantalum along with silver and manganese in an efficient and environmentally friendly manner from tantalum capacitor scrap.Publicationtype: Journal ArticleScopus© Citations 1 40 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Untersuchung des Verhaltens von Beuteln aus biologisch abbaubaren Kunststoffen in der Kompostierungsanlage Neumünster(Witzenhausen-Institut für Abfall, Umwelt und Energie, 2023-04); ; ; ; Abbauversuche mit als kompostierbar zertifizierten Bioabfallsammelbeuteln wurden in einer Kompostierungsanlage mit Haupt- und Nachrotte über einen Zeitraum von bis zu sechs Wochen durchgeführt. Aussagen zum Beutelabbau wurden über die verbliebenen Makro-, Meso- und Mikropartikel getroffen. Der Praxisversuch wurde mit Laboruntersuchungen zur Beutelcharakteristik und zum Abbauverhalten im anaeroben Milieu ergänzt. Darüber hinaus wurde die aktuelle Situation der Bioabfallsammlung in deutschen Kommunen bewertet und Schlussfolgerungen für den Einsatz von BAK-Beuteln in der Praxis der Bioabfallsammlung gezogen.Publicationtype: Conference Paper67 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Chemical and microbial leaching of valuable metals from PCBs and tantalum capacitors of spent mobile phones(Multidisciplinary Digital Publishing Institute (MDPI), 2022-08-13); ; ; ; We compared chemical and microbial leaching for multi-metal extraction from printed circuit boards (PCBs) and tantalum capacitor scrap. A mixed consortium of acidophiles and heterotrophic fungal strains were used in the experiments and compared to chemical leaching using specific acids (sulfuric, citric and oxalic acids). Under optimum conditions, 100% extraction efficiency of Cu, and nearly 85% of Zn, Fe, Al and Ni were achieved from PCB and tantalum capacitor scrap samples using sulfuric acid. The mixed consortium of acidophiles successfully mobilized, Ni and Cu (99% and 96%, respectively) while Fe, Zn, Al and Mn reached an extraction yield of 89, 77, 70 and 43%, respectively, from the PCB samples. For the tantalum capacitor samples, acidophiles mobilized 92% Cu, 88% Ni, 78% Fe, 77% Al, 70% Zn and 57% Mn. Metal mobilization from PCBs and tantalum capacitor scrap by A. niger filtrate showed efficient solubilization of Cu, Fe, Al, Mn, Ni, Pb and Zn at an efficiency of 52, 29, 75, 5, 61, 21 and 35% from PCB samples and 61, 25, 69, 23, 68, 15 and 45% from tantalum capacitor samples, respectively. Microbial leaching proved viable as a method to extract base metals but was less specific for tantalum and precious metals in electronic waste. The implications of these results for further processing of waste electronic and electrical equipment (WEEE) are considered in potential hybrid treatment strategies.Publicationtype: Journal ArticleScopus© Citations 7 83 135 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , The presence of rare earth elements and critical metals in waste electric and electronic equipment: challenges for recovery(2019-01-07); ; ; The fast growth of waste electric and electronic equipment (WEEE) is not only a threat to our environment, but also a great source of rare earth elements (REEs) and critical metals (CMs). Despite the fact that Directive 2012/19/EU encourages the treatment of WEEE by setting targets for collection, re-use and recycling, it does not directly target the recycling of REEs and CMs. The insufficient data about the composition of REEs and CMs in electric and electronic equipment (EEE), the high recycling costs and the different motivations/interests of the stakeholders are some of the main inhibiting factors. Recently, scientific community pays much attention to the recovery and recycling of REEs and CMs due to several associated benefits. Hence this work highlights the economic importance of REEs and CMs in terms of their inevitability in EEE. Then, an overview of the supply risk of REEs and CMs and the challenges related to the recovery are provided.Publicationtype: Journal Article106