Plastic waste gasification using oxygen-enriched air and steam: Experimental and model results from a large pilot-scale reactor.

Advanced thermochemical technologies for plastic waste valorization represent an interesting alternative to waste-to-energy options. They are particularly appealing for waste-to-hydrogen and waste-to-chemicals applications, with autothermal steam-oxygen gasification in fluidized bed reactors showing the greatest market potential. The study describes a series of experimental tests carried out on a large pilot-scale fluidized bed gasifier, using steam and O-enriched air, with increasing fractions of oxygen.

Waste-derived catalysts for tar cracking in hot syngas cleaning.

Catalytic tar cracking is a promising technique for hot syngas cleaning unit in gasification plants because it can preserve tars chemical energy, so increasing the syngas heating value. The cost associated with catalyst preparation is a key issue, together with its deactivation induced by coke deposition. Iron is a cheap and frequently used catalyst, which can also be found in some industrial wastes.

An LCA answer to the mixed plastics waste dilemma: Energy recovery or chemical recycling?

The study focuses on mixed plastics waste (MPW), whose complex and unpredictable composition (due to high polymer heterogeneity, additives, and contaminants) makes its valorisation a true technical, environmental, economic, and regulatory challenge. Chemical recycling by means of advanced thermochemical treatments (ATT) could be a successful strategy, able to support the transition from a carbon intensive to a carbon negative sector, and alternative to the current treatments of energy recovery or mechanical downcycling. Some of these ATTs provide an efficient recovery of valuable resources, such as fuels and chemicals, but their role is mainly limited by time necessary to complete the process optimization and implement the required infrastructures.

How to enhance the environmental sustainability of WEEE plastics management: An LCA study.

A new management scheme of plastics from waste of electrical and electronic equipment (WEEE), which includes novel treatments of sorting, dissolution/precipitation, extrusion, catalytic pyrolysis, and plastic upgrading, is proposed. Its environmental performances are quantified by an attributional Life Cycle Assessment and compared with those of European currently adopted schemes, which include conventional mechanical recycling and thermal treatments as well as improper options of dumping and open burning, largely applied to WEEE plastics exported to developing countries. The proposed innovative scheme greatly enhances the environmental sustainability of WEEE plastics management, by increasing the annual amounts of polymers sent to recycling (from 390 kt/y up to 530 kt/y), decreasing residues to be sent to combustion (from 360 kt/y up to 60 kt/y), and reducing the potential impacts of all the midpoint categories under analysis (up to 580% for that of Global Warming).

About the environmental sustainability of the European management of WEEE plastics.

A huge increase of waste of electrical and electronic equipment (WEEE) is observing everywhere in the world. Plastic component in this waste is more than 20% of the total and allows important environmental advantages if well treated and recycled. The resource recovery from WEEE plastics is characterised by technical difficulties and environmental concerns, mainly related to the waste composition (several engineering polymers, most of which containing heavy metals, additives and brominated flame retardants) and the common utilisation of sub-standard treatments for exported waste.

Environmental performances of a modern waste-to-energy unit in the light of the 2019 BREF document.

The study compares the environmental performances of a new-generation, large scale, combustion-based waste-to-energy unit, active since 2010, with those of different "virtual" units, defined in the light of the Best Available Techniques REFerence document (BREF) for Waste Incineration published by the European Community on December 2019. The average performances of these units have been evaluated in terms of air emissions, material consumptions and energy recovery, based on data related to 355 "existing" European waste incineration lines and those established for the future "new" plants. An attributional Life Cycle Assessment has been used to compare and quantify the environmental performances of the selected units, all equipped with a moving grate furnace and similar air pollution control systems.

Biowaste-to-Biomethane: An LCA study on biogas and syngas roads.

Biomethane produced from waste-derived biomass (biowaste) is a clean and renewable fuel, which offers substantial reductions of greenhouse gas emissions and resource consumption. Biomethane is currently produced via the "biogas road", which includes the anaerobic digestion of wet biowaste and a successive upgrading of obtained biogas, with good environmental performance. An alternative production strategy is the "syngas road", which includes the gasification of dry or semi-dry biowaste followed by cleaning, conditioning, methanation, and final upgrading of obtained syngas.

Environmental performances of different configurations of a material recovery facility in a life cycle perspective.

The study evaluated the environmental performances of an integrated material recovery facility (MRF) able to treat 32kt/y of unsorted mixed waste, made of residuals from household source separation and separate collection. The facility includes a mechanical sorting platform for the production of a solid recovered fuel (SRF) utilized in an external waste-to-energy plant, bio-cells for tunnel composting of organic fraction, and a sanitary landfill for the safe disposal of ultimate waste. All the MRF sub-units have been analysed in depth in order to acquire reliable data for a life cycle assessment study, focused on the environmental performances of different configurations of the facility.

A life cycle assessment of environmental performances of two combustion- and gasification-based waste-to-energy technologies.

An attributional life cycle analysis (LCA) was developed to compare the environmental performances of two waste-to-energy (WtE) units, which utilize the predominant technologies among those available for combustion and gasification processes: a moving grate combustor and a vertical shaft gasifier coupled with direct melting. The two units were assumed to be fed with the same unsorted residual municipal waste, having a composition estimated as a European average. Data from several plants in operation were processed by means of mass and energy balances, and on the basis of the flows and stocks of materials and elements inside and throughout the two units, as provided by a specific substance flow analysis.