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Separately collected food waste (SC-FW) is effectively recycled through industrial anaerobic digestion (AD) and composting. However, the presence of improper materials in SC-FW not only generates technical problems to AD and composting, but also lowers the quality of the outputs of the processes. As a consequence, improper materials found in SC-FW cause not negligible environmental and economic burdens. In this study, the environmental and economic impacts due to the presence of unsuitable materials in the SC-FW, determined through compositional analysis, were estimated through life cycle assessment and environmental life cycle costing approaches. Three different scenarios were analysed for both AD and composting processes: (i) the current situation (CS); (ii) the improved scenario (AS) with an amount of improper materials in SC-FW reduced to 3 % (w/w); (iii) the ideal scenario (IS) with the total absence of foreign materials. Environmental benefits were determined for the AS and IS scenarios in 17 of the 19 analysed impact categories. Considering the GHG emissions, higher savings were measured for AD in AS and IS scenarios (47 % and 79 %, respectively) than in CS scenario. Similarly, savings of -10.4 kg fossil oil eq/tonSC-FW (AS) and - 17.1 kg fossil oil eq/tonSC-FW (IS) for AD could be obtained with respect to the CS scenario. Greater economic benefits were calculated for AD (-76.4 €/tonSC-FW) and composting (-52.2 €/tonSC-FW) in the IS scenario. Savings up to € 2,249,780 and € 3,888,760 could have been obtained in 2022 by reducing to 3 % (w/w) and eliminating, respectively, the amount of improper materials in the SC-FW. The results of the compositional analyses of SC-FW allowed to identify the incorrect behaviours in FW source-sorting activity and to plan interventions to improve the current FW management system. The quantified environmental and economic benefits could further motivate citizens to correctly differentiate FW.

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The production of dimethyl ether from renewables or waste is a promising strategy to push towards a sustainable energy transition of alternative eco-friendly diesel fuel. In this work, we simulate the synthesis of dimethyl ether from a syngas (a mixture of CO, CO2 and H2) produced from gasification of digestate. In particular, a thermodynamic analysis was performed to individuate the best process conditions and syngas conditioning processes to maximize yield to dimethyl etehr (DME). Process simulation was carried out by ChemCAD software, and it was particularly focused on the effect of process conditions of both water gas shift and CO2 absorption by Selexol® on the syngas composition, with a direct influence on DME productivity. The final best flowsheet and the best process conditions were evaluated in terms of CO2 equivalent emissions. Results show direct DME synthesis global yield was higher without the WGS section and with a carbon capture equal to 85%. The final environmental impact was found equal to -113 kgCO2/GJ, demonstrating that DME synthesis from digestate may be considered as a suitable strategy for carbon dioxide recycling.

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The biomass-to-methanol process may play an important role in introducing renewables in the industry chain for chemical and fuel production. Gasification is a thermochemical process to produce syngas from biomass, but additional steps are requested to obtain a syngas composition suitable for methanol synthesis. The aim of this work is to perform a computer-aided process simulation to produce methanol starting from a syngas produced by oxygen-steam biomass gasification, whose details are reported in the literature. Syngas from biomass gasification was compressed to 80 bar, which may be considered an optimal pressure for methanol synthesis. The simulation was mainly focused on the water-gas shift/carbon capture sections requested to obtain a syngas with a (H2 - CO2)/(CO + CO2) molar ratio of about 2, which is optimal for methanol synthesis. Both capital and operating costs were calculated as a function of the CO conversion in the water-gas shift (WGS) step and CO2 absorption level in the carbon capture (CC) unit (by Selexol® process). The obtained results show the optimal CO conversion is 40% with CO2 capture from the syngas equal to 95%. The effect of the WGS conversion level on methanol production cost was also assessed. For the optimal case, a methanol production cost equal to 0.540 €/kg was calculated.

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Automotive shredder residue (ASR) can create difficulties when managing, with its production increasing. It is made of different type of plastics, foams, elastomers, wood, glasses and textiles. For this reason, it is complicated to dispose of in a cost effective way, while also respecting the stringent environmental restrictions. Among thermal treatments, pyrolysis seems to offer an environmentally attractive method for the treatment of ASR; it also allows for the recovery of valuable secondary materials/fuels such as pyrolysis oils, chars, and gas. While, there is a great deal of significant research on ASR pyrolysis, the literature on higher scale pyrolysis experiments is limited. To improve current literature, the aim of the study was to investigate the pyrolysis of ASR in a bench scale rotary kiln. The Italian ASR was separated by dry-sieving into two particle size fractions: d<30mm and d>30mm. Both the streams were grounded, pelletized and then pyrolyzed in a continuous bench scale rotary kiln at 450, 550 and 650°C. The mass flow rate of the ASR pellets was 200-350g/h and each test ran for about 4-5h. The produced char, pyrolysis oil and syngas were quantified to determine product distribution. They were thoroughly analyzed with regard to their chemical and physical properties. The results show how higher temperatures increase the pyrolysis gas yield (44wt% at 650°C) as well as its heating value. The low heating value (LHV) of syngas ranges between 18 and 26MJ/Nm3dry. The highest pyrolysis oil yield (33wt.%) was observed at 550°C and its LHV ranges between 12.5 and 14.5MJ/kg. Furthermore, only two out of the six produced chars respect the LHV limit set by the Italian environmental regulations for landfilling. The obtained results in terms of product distribution and their chemical-physical analyses provide useful information for plant scale-up.

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Silicon carbide powders have been synthesized from tires utilizing a patented recycling process. Dynamic light scattering, Raman spectroscopy, SEM microscopy, and X-ray diffraction have been carried out to gather knowledge about powders and the final composite structure. The obtained powder has been proven to induce resistive switching in a PMMA polymer-based composite device. Memory effect has been detected in two-terminal devices having coplanar contacts and quantified by read-write-erase measurements in terms of level separation and persistence.

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Corn stover was treated by steam explosion process at four different temperatures. A fraction of the four exploded matters was extracted by water. The eight samples (four from steam explosion and four from water extraction of exploded matters) were analysed by wet chemical way to quantify the amount of cellulose, hemicellulose and lignin. Thermogravimetric analysis in air atmosphere was executed on the eight samples. A mathematical tool was developed, using TGA data, to determine the composition of corn stover in terms of cellulose, hemicellulose and lignin. It uses the biomass degradation temperature as multiple linear function of the cellulose, hemicellulose and lignin content of the biomass with interactive terms. The mathematical tool predicted cellulose, hemicellulose and lignin contents with average absolute errors of 1.69, 5.59 and 0.74 %, respectively, compared to the wet chemical method.

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