Umberto Arena

• Full Professor, Ph. D. in Chem. Eng.
• Professor (Full) at University of Campania "Luigi Vanvitelli"

A municipal solid waste information system, named W-MySir, is utilised to acquire high-quality data to implement an attributional life-cycle assessment (LCA) focused on the evolution of the environmental performances of municipal solid waste management in a specific area. The main aim was to investigate how this combined approach can be used for mo...

The recovery of resources from streams of mixed plastics waste is a technological and economic challenge since they contain various (and generally non-compatible) polymers, different (and often hazardous) additives, as well as multilayer structures and fiber-reinforced composites. Only a too limited part of these plastics - such as those coming fro...

Syngas produced by biomass and waste gasification processes must be adequately clean of tar compounds before being utilized in value‐added applications. The syngas cleaning by tar cracking at high temperatures is a promising technique, which can utilize different kinds of catalysts. However, their use is limited by deposition of coke layers, which...

Activated carbons are recognised as inexpensive, easily available, and efficient catalysts for tar cracking reactions at high temperatures. Their use in hot syngas cleaning is limited by the rapid deactivation resulting from the coke deposition, and the consequent masking phenomenon over the activated carbon surface. This study contributes to a bet...

Plastic from end-of-life vehicles (ELVP) are currently managed in Europe Union without any attention to polymer recovery. The study analyses novel treatments of sorting, dissolution/precipitation, extrusion, catalytic pyrolysis, and plastic upgrading, which could contribute to define a sustainable ELVP management scheme. The environmental performan...

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 Eu...

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 c...

Air gasification tests have been carried out in a pilot scale bubbling fluidized bed gasifier, able to treat up to 100 kg/h of Eucalyptus wood chips, and operated, under chemical and thermal steady-state conditions, at different values of equivalence ratio. The results are reported in terms of the main process performance parameters and transfer co...

The study reviews and compares the most utilised techniques to obtain high quality biomethane by upgrading biogas from anaerobic digestion of the organic fraction of municipal solid waste. Environmental and economic aspects of membrane separation, water scrubbing, chemical absorption with amine solvent, and pressure swing adsorption have been quant...

The environmental performances of four market-available thermochemical and biochemical processes for energy production from municipal solid biowaste have been compared by means of a combined utilisation of Life Cycle Assessment and Material Flow Analysis. The thermochemical options are those of co-combustion and co-gasification with an unsorted res...

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 averag...

Sewage sludge pyrolysis liquid (SSPL) is a mixture of various toxic organic compounds and moisture, its disposal or valorization are crucial for the sustainability of any pyrolysis plant of sewage sludge (SS). As SSPL showed strong inhibition on anaerobic digestion (AD), in order to fulfill its clean disposal, the study investigates its AD in cow d...

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 envi...

The study evaluated the environmental performance of the construction and demolition waste (C&DW) management in the area of PCJ Watershed, located in the São Paulo State, Brazil, by means of an attributional Life Cycle Assessment. The entire C&DW management under the responsibility of the municipal government was considered. The potential environme...

The study provides for the first time a life cycle inventory model for the fluidized bed gasification of wastes, based on a large amount of high-quality data. All of them have been obtained from a pilot scale fluidized bed gasifier, fed with ten types of waste and biomass, under a wide range of operating conditions. The model refers to commercial s...

We are pleased to recognize some of our top reviewers for 2017. In 2017, the journal requested external reviews for 1186 manuscripts and 5429 external reviews were submitted, with some reviewers providing as many as 11 reviews. As co-editors-in-chief, we extend our sincere thanks to all of our reviewers. In this issue, we are pleased to recognize 3...

This work studies the heterogeneous conversion of naphthalene over different chars at 800 degrees C and 900 degrees C with gas residence times ranging from 0.05 s to 0.15 s. The aim was to analyse the role of the pore size distribution and surface composition on the catalytic activity of the char during batch experiments with a steady gas flow dope...

An attributional, process-based, comparative Life Cycle Assessment has been developed to quantify and compare the environmental performances of a detached house, located in a seismic area of the Southern Italy, designed following two different approaches for its structural components: by using Cold Formed Steel (CFS), with sheathing and insulating...

Volatile compounds produced from pyrolysis of municipal solid waste (MSW) are treated in a scrubbing system, which includes a hot char filter, a condenser cooled with ice water, a cooking oil scrubber and a Na2CO3 solution scrubber, aimed at obtaining high quality syngas. The performances of each treatment device are evaluated at a laboratory scale...

The study aims to demonstrate the overall environmental sustainability of biomethane production by anaerobic digestion of the separately collected organic fraction of municipal solid waste. There is a great interest in the utilisation of biofuels produced from biowaste in the transport sector, due to the benefits of reduced pollutant emissions and...

The study describes an attributional life cycle assessment carried out according to the ISO standards and focused on an Italian multifamily residential building. The aim was developing an exhaustive and reliable inventory of high-quality primary data, comparing the environmental impacts along the three stages of the building life cycle. The pre-use...

Obtaining high quality syngas from sewage sludge (SS) means transferring a low-grade SS into a high-grade fuel or raw materials for chemical products. In this study, Fe is added to SS in form of Fe2(SO4)3 to produce an effective and self-sufficient catalyst in order to obtain more syngas and minimize liquid products from SS pyrolysis. The Fe-embedd...

The study evaluated the environmental performances of an integrated material recovery facility (MRF) able to treat 32 kt/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...

Volatile products obtained from pyrolysis of municipal solid waste (MSW), including syngas and pyrolysis oil, were forced to contact the hot char from the same pyrolysis process at 500–600 °C in a fixed bed reactor to be reformed. The yields and properties of syngas, char and pyrolysis liquid were investigated; and the energy re-distribution among...

The natural and mixed recycled aggregate production for use as road base and subbase have been compared through an attributional life cycle assessment. The primary data have been collected in a basalt natural aggregate production facility and in a recycling facility of mixed aggregate, both located in Southeast Brazil. The topic is important since...

The study investigates the potential environmental impacts related to the end-of-life phase of a residential building, identified in a multifamily dwelling of three levels, constructed in the South of Italy by utilizing conventional materials and up-to-date procedures. An attributional life cycle assessment has been utilised to quantify the contrib...

The study evaluates the technical feasibility of the fluidized bed gasification of three solid recovered fuels (SRFs), obtained as co-products of a recycling process. The SRFs were pelletized and fed to a pilot scale bubbling fluidized bed reactor, operated in gasification and co-gasification mode. The tests were carried out under conditions of the...

: The paper investigates on a demonstrative scale the technical and environmental aspects of an innovative recycling process of wastes generated by the utilization of absorbent hygiene products (AHPs). The recycling process includes three main sections. An autoclave, coupled with a sorting machine, provides the sterilization of AHP waste and the se...

The paper investigates technical, environmental and social aspects of an innovative recycling process of wastes generated by the utilization of absorbent hygiene products (AHPs). The study is part of a LIFE+ project, named Virgin (Highly-efficient ValorIsation of AHP waste thRough a novel combination of autoclave and GasIficatioN). The project aime...

The removal of tar compounds from the syngas produced by biomass or waste fluidized bed gasification is the greatest technical challenge for a wider application of the technology. These heavy polynuclear hydrocarbons are characterized by high dew point temperatures (generally above 300°C), and then can condense along pipes, heat exchangers and part...

The paper investigates technical and environmental aspects of an innovative recycling process of wastes generated by the utilization of absorbent hygiene products (AHPs). The recycling process consists of three main sections: an autoclave, which provides the necessary steam sterilization of AHP waste, and it is connected to a sorting machine, which...

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 assu...

: Cellulosic and plastic wastes obtained as co-products by an industrial process were fed in a pilot-scale bubbling fluidized bed gasifier. The experimental runs were carried out with cellulose, plastic and a mixture of plastic and cellulose, at equivalence ratios between 0.2 and 0.4 and temperatures between 800 and 900°C, in a fluidized bed of oli...

: An attributional life cycle analysis (LCA) was developed for two waste-to-energy (WtE) units, which utilize a moving grate combustor and a vertical shaft gasifier coupled with direct melting, respectively. The WtE units were assumed to be fed with the same unsorted residual municipal waste, having a composition estimated as a European average. Da...

The whole range of waste-to-energy technologies can be grouped into two main categories: combustion-and gasification-based thermal treatment. The first is a well established and sustainable technology that results in considerable waste volume reduction with the added ability to reclaim a significant amount of energy: there are more than 900 plants...

The effect of ash composition on the fluidized bed gasification behaviour of poultry wastes was investigated by operating a pre-pilot scale reactor with two batches of manure obtained from an industrial chicken farm. The experimental runs were carried out by keeping the fluidized bed velocity fixed (at 0.4m s(-1)) and by varying the equivalence rat...

The chapter describes the state-of-the-art of fluidized bed gasification of solid fuels, starting from the key role played by hydrodynamics, and its strong correlation with physical and chemical phenomena of the process and operating performance parameters of the reactor. The possible configurations of fluidized bed gasification plants are also ass...

The paper describes the results of a research program aimed at assessing the technical and economical feasibility of a fluidized bed gasifier able to treat 5000 t/y of a Secondary Recovered Fuel (SRF) obtained from a sorting process of municipal solid waste collected in an area of the Middle of Italy. A pilot scale bubbling fluidized bed air gasifi...

Two plastic waste-derived fuels obtained as co-products from industrial processes were fed in a pilot-scale bubbling fluidized bed gasifier, having a maximum thermal output of about 400kW. The experimental runs were carried out by reaching a condition of thermal and chemical steady state under values of equivalence ratio ranging from 0.2 to 0.3. Ol...

A restwaste obtained as a residual stream from a sorting platform of municipal solid waste was fed in a pilot-scale bubbling fluidized bed gasifier, having an internal diameter of 0.38m, a maximum feeding capacity of 100kg/h and a maximum thermal output of about 350kW. Samplings and measurements taken during the experimental tests allow to obtain...

The paper describes the implementation of an innovative waste management planning approach to the Waste Management Planning of two Italian Regions: Molise, in the middle of Italy, and Campania, which has been the scene of a recent and dramatic waste emergency. The applied approach is based on the extensive utilization of Material and Substance Flo...

A critical comparison between combustion- and gasification-based waste-to-energy systems needs a deep knowledge of the mass flows of materials and elements inside and throughout the units. The study collected and processed data from several moving grate conventional incinerators and high-temperature shaft gasifiers with direct melting, which are in...

The bubbling fluidized bed combustors and gasifiers could both be proposed as a convenient conversion section of a plastics-to-energy plant having a medium-size throughput (8-30MW). In order to develop a preliminary comparison of their process performances, a number of tests was carried out in two pilot scale bubbling fluidized bed reactors, a comb...

The effect of oxygen-enriched air during fluidized bed co-gasification of a mixture of coal, plastics and wood has been investigated. The main components of the obtained syngas were measured by means of on-line analyzers and a gas chromatograph while those of the condensate phase were off-line analysed by means of a gas chromatography-mass spectrom...

The paper proposes a critical assessment of municipal solid waste gasification today, starting from basic aspects of the process (process types and steps, operating and performance parameters) and arriving to a comparative analysis of the reactors (fixed bed, fluidized bed, entrained bed, vertical shaft, moving grate furnace, rotary kiln, plasma re...

The paper aims to provide data for a critical comparison of the two WtE options, by means of a description of the performance of a combustion-and a gasification-based process (in the following indicated as CB-WtE and GB-WtE), applied to the same solid waste and carried out in a moving grate furnace and in a high temperature vertical shaft gasifier...

A comparison between the most promising design configurations for the industrial application of gasification based, plastics-to-energy cogenerators in the 2-6 MWe range is presented. A pilot scale bubbling fluidized bed air gasifier, having a feeding capacity of 100 kg/h, provided experimental data: the syngas complete composition, the characteriza...

Seven mixtures of coals, plastics and wood have been pelletized and fed into a pre-pilot scale fluidized bed gasifier in order to investigate the main aspects of the co-gasification of these materials. The main components of the obtained syngas (CO, H2, CO2, N2, CH4, CnHm) were measured by means of on-line analyzers and a gas cromatograph. The perf...

Biomass has great potential as a clean and renewable feedstock for producing modern energy carriers. This paper focuses on the process of biomass gasification, wherein the synthesis gas is subsequently used to produce electricity. A comparison between the most promising design configurations for the industrial application of gasification based, bio...

Three commercially available biomass fuels, made of natural and waste wood, were fed in a pilot scale bubbling fluidized bed gasifier having an internal diameter of 0.381 m and a maximum feeding capacity of 100 kg/h. The experimental runs were carried out at about 850°C and under values of the equivalence ratio between 0.20 and 0.30. The fluidized...

Five alternative waste-derived fuels obtained from municipal solid waste and different post-consumer packaging were fed in a pilot-scale bubbling fluidized bed gasifier, having a maximum feeding capacity of 100 kg/h. The experimental runs utilized beds of natural olivine, quartz sand or dolomite, fluidized by air, and were carried out under various...

A comparison between the most promising design configurations for the industrial application of gasification based, plastics-to-energy cogenerators in the 2-6MWe range is presented. A pilot scale bubbling fluidized bed air gasifier, having a feeding capacity of 100kg/h, provided experimental data: the syngas complete composition, the characterizati...

A comparison between the most promising design configurations for the industrial application of gasification based, biomass-to-energy cogenerators in the 100-600kWe range is presented. Mass and energy balances and material and substance flow analyses drawn for each design solutions are based on the experimental data obtained from a pilot scale bubb...

In the Campania region, an area in the south of Italy with 5.7 million inhabitants and a production of about 7,900 tonnes of municipal solid waste per day, an emergency situation was created by inappropriate waste management policy and practice. In order to support decisions regarding future solutions for this crisis, reliable, transparent, and imp...

A natural biomass was fed in a pilot scale bubbling fluidized bed gasifier, having a maximum feeding capacity of 100kg/h. Measurements included the syngas composition, the mass flow rate and composition of entrained fines collected at the cyclone and purge material from the wet scrubber, and the bed material characterization. The performance of the...

A recycled polyethylene was fed in a pilot plant bubbling fluidized bed gasifier, having an internal diameter of 0.381 m and a maximum feeding capacity of 90 kg/h. The experimental runs were carried out under various operating conditions: the bed temperature was kept at about 850 degrees C, the equivalence ratio varied between 0.2 and 0.35, the amo...

Natural olivine was used as bed material during the gasification of plastic waste in a pilot-scale bubbling fluidized bed reactor. The results indicate that it works as an excellent in-situ tar reduction agent, considerably improving the quality of the gas produced, in terms of low tar content, high hydrogen volume fraction and large syngas yield....

This paper describes the utilization of the Recursive Operability Analysis for the identification of accident scenarios of a pilot plant gasifier fed with solid wastes and alternative fuels. The procedure was used for the identification of situations of potential risk during the operation of the plant and, coupled with the Fault Tree algorithm, in...

A bed of natural olivine was used during the gasification of a plastic waste in a pilot plant bubbling fluidized bed reactor. The olivine remarkably improves the quality of the product gas, in terms of low tar content, high hydrogen volume fractions and large syngas yield. It also produces a certain amount of solid carbon that deposits on bed parti...

A bubbling fluidized bed reactor 102mmID has been used as pyrolyser by feeding polyethylene-terephtalate at two different reactor temperatures. Experiments were carried out with the aim to quantify the yield and composition of gas, liquids and to characterize the solid phase. The solid phase has been characterized by means of different methods: TG-...

A new technique for a continuous, mass production of high-quality multi-wall carbon nanotubes (MWCNTs), based on fluidized bed pyrolysis of polymers (virgin or recycled polyolefins and recycled polyethylene terephtalate), is described in detail. The study investigates the role of interactions between the bed material and the polymer particles injec...

A recycled polyethylene was fed in a pilot plant bubbling fluidized bed gasifier, having a maximum feeding capacity of 60kg/h. The experimental runs were carried out under various operating conditions: the bed temperature was kept at about 850°C, the equivalence ratio varied between 0.2 and 0.35, the fluidizing velocity between 0.5 and 0.7m/s, quar...

Pyrolysis and gasification processes of plastic wastes in a fluidized bed reactor can be schematically decomposed into three major steps: devolatilization; gas phase reactions in the bed; gas phase reactions in the freeboard. The devolatilization phase defines the true feed composition to the reactor and is the first step in the whole process. The...

An innovative process for a mass production of multi-wall carbon nanotubes (MWCNTs) by means of pyrolysis of virgin or recycled polyolefins is described. The technique uses solid–gas fluidised bed reactors, continuously operated under conditions which allow high heating rates of the polymers, high heat and material exchange coefficients and a relia...

A new technique for a continuous, mass production of high-quality multi-wall carbon nanotubes (MWCNTs), based on fluidized bed pyrolysis of polymers (like virgin or recycled polyolefins and recycled polyethylene terephtalate), is described in detail. The study investigates the role of interactions between the bed material and the polymer particles...

The paper studies in depth a new technique for mass production of MWCNTs that is based on thermal cracking of polymers in a solid-gas fluidized bed reactor, operated under specific thermal and hydrodynamic conditions. The paper provides information about the phenomenology of interactions between the bed material and the polymer particles injected i...

Life cycle assessment (LCA) methodology is generally considered one of the best environmental management tools that can be used to compare alternative eco-performances of recycling or disposal systems. It considers the environment as a whole, including indirect releases, energy and material consumption, emissions in the environment, and waste dispo...

The risk of occurrence of phenomena inducing worsening of fluidisation quality and eventually leading to bed defluidisation is one of the major constraints to an easier utilisation of fluidised beds for the low-temperature pyrolysis of plastic wastes. In order to investigate these phenomena, different mixtures of plastic wastes, obtained by combina...

Investigating the environmental sustainability of any recycling process demands full understanding and objective quantification of all the associated environmental impacts. Life cycle assessment is an internationally standardized method that is able to account for upstream and downstream inputs and emissions over the complete supply chain providing...

The quantification of the actual environmental advantage of mechanical recycling of post-consumer PET and PE liquid containers was the main aim of the study. The phases of collection, compaction, sorting, reprocessing and refuse disposal in the Italian system of plastic packaging waste recycling were individually analysed and quantified in terms of...

Developed from chemical engineering principles and energy analysis, the life cycle assessment is an internationally standardized method that is able to account for upstream and downstream inputs and emissions related to the life cycle of a product or a service. It is generally considered the best environmental management tool that can be used to ob...

The paper describes the design of two mitigation systems adopted by an important food company, which uses ammonia for its refrigeration plant. The results of an accurate risk analysis identified the critical risk areas and the alternative mitigation systems. Two different approaches were used for indoor and outdoor accidents. A specific model was d...