Search

The assessment of the impact of different catastrophic events in a given area requires innovative approaches that allow risks comparison and that account for all the possible risk interactions. In the common practice, the risk evaluation related to different sources is generally done through independent analyses, adopting disparate procedures and time--space resolutions. Such a strategy of risks evaluation has some evident major drawbacks as, for example, it is difficult (if not impossible) to compare the risk of different origins, and the implicit assumption of independence of the risk sources leads to neglect possible interactions among threats and/or cascade effects. The latter may amplify the overall risk, and potentially the multi-risk index could be higher than the simple aggregation of single-risk indexes calculated considering each source as independent from the others. In this paper, we put forward some basic principles for multi-risk assessment, and we consider a real application to Casalnuovo municipality (Southern Italy), in which we face the problem to make different hazards comparable, and we highlight when and how possible interactions among different threats may become important. © 2012 Springer Science+Business Media B.V.

Material and energy recovery from waste is significantly growing its importance in the last decades aiming to reduce the primary resources exploitation and the excessive recourse to incineration and landfilling. Several processes, technologies and methods can be chosen to design a proper waste management system (WMS) so that an objective comparison between alternatives has to be made. To this end, Life Cycle Assessment (LCA) can be used to compare possible alternative scenarios and create an evaluation grid where different environmental parameters are reported. The aim of this work was to compare the environmental impacts of four different scenarios already analysed for technological and economic aspects in a previous work. The scenario taken as base case referred to a real waste management system applied in Caserta Province, an area of 924,614 inhabitants in the Campania region of Southern Italy. The base scenario considers the household separation of waste in five fractions addressed to material recovery (polyethylene, polyethylen-terephtalate, polypropylene, metals, cellulosic fibers,...), composting (biowaste) and incineration (residual waste). The results of the LCA demonstrated that the best scenario is that one including the highest separate collection rate technically and economically feasible to be carried out i.e. 60%, the recourse to anaerobic digestion and biogas production to treat the biowaste separately collected and the maximization of the re-processing of recyclable materials such as PET, HDPE, glass, metals,... In particular, the Global Warming Potential decrease of 166% and the Eutrophication Potential decrease of 646%, when the alternative scenario, including the recalled features is compared to the base-case one. The most important result is that the raised separate collection of recyclable materials utilized as substitutes of raw materials and of biowaste utilized for production of renewable energy helps to mitigate the direct and indirect burdens connected to the overall life cycle of goods production. Crown Copyright (C) 2017 Published by Elsevier Ltd. All rights reserved.

The main role of a waste management plan is to define which is the combination of waste management strategies and method needed to collect and manage the waste in such a way to ensure a given set of targets is reached. Objectives have to be sustainable and realistic, consistent with the environmental policies and regulations and monitored to verify the progressive achievement of the given targets. To get the aim, the setting up and quantification of indicators can allow the measurement of efficiency of a waste management system. The quantification of efficiency indicators requires the developing of a material flow analysis over the system boundary, from waste collection to secondary materials selling, processing and disposal. The material flow analysis has been carried out with reference to a case study for which a reliable, time- and site-specific database was available. The material flow analysis allowed the evaluation of the amount of materials sent to recycling, to landfilling and to waste-to-energy, by highlighting that the sorting of residual waste can further increase the secondary materials amount. The utilisation of energy recovery to treat the low-grade waste allows the maximisation of waste diversion from landfill with a low production of hazardous ash. A preliminary economic balance has been carried out to define the gate fee of the waste management system that was in the range of 84–145 € t−1 without including the separate collection cost. The cost of door-by-door separate collection, designed to ensure the collection of five separate streams, resulted in 250 € t−1 ±30%.

Most of the integrated systems for municipal solid waste management aim to increase the recycling of secondary materials by means of physical processes including sorting, shredding and reprocessing. Several restrictions prevent from reaching a very high material recycling efficiency: the variability of the composition of new-marketed materials used for packaging production and its shape and complexity are critical issues. The packaging goods are in fact made of different materials (aluminium, polymers, paper, etc.), possibly assembled, having different shape (flat, cylindrical, one-dimensional, etc.), density, colours, optical properties and so on. These aspects limit the effectiveness and efficiency of the sorting and reprocessing plants. The scope of this study was to evaluate the performance of a large scale Material Recovery Facility (MRF) by utilizing data collected during a long period of monitoring. The database resulted from the measured data has been organized in four sections: (1) data related to the amount and type of inlet waste; (2) amount and composition of output products and waste; (3) operating data (such as worked hours for shift, planned and unscheduled maintenance time, setting parameters of the equipment, and energy consumption for shift); (4) economic data (value of each product, disposal price for the produced waste, penalty for non-compliance of products and waste, etc.). A part of this database has been utilized to build an executive dashboard composed by a set of performance indicators suitable to measure the effectiveness and the efficiency of the MRF operations. The dashboard revealed itself as a powerful tool to support managers and engineers in their decisions in respect to the market demand or compliance regulation variation as well as in the designing of the lay-out improvements. The results indicated that the 40% of the input waste was recovered as valuable products and that a large part of these (88%) complied with the standards of the recycling companies. The evaluation of the indicators led to the decision to modify the layout to improve the interception of some polymers for which the performance indicators were poor. In particular, two additional optical sorters have to be inserted to increase the yield indicator and to the overall performance of the facility. Definitely, the results of the work allowed to: increase the yield and purity of products’ flows; ensure the compliance of waste flows; increase the workability.

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 characterization of the bed material, the entrained fines collected at the cyclone and the purge material from the scrubber. Mass and energy balances and material and substance flow analyses have been therefore drawn to assess and compare design solutions utilizing two mixed plastic wastes (MPW) obtained from separate collection of plastic packaging, after different levels of pre-treatments. The related techno-economic performances have been finally estimated on the basis of the manufacturer’s specifications. The study concludes that the MPW obtained after a very simple pre-treatment and fed to a gasifier coupled with a steam turbine is the solution that currently offers the higher reliability and provides the higher internal rate of return for the investigated range of electrical energy production.

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 values of equivalence ratio. The process resulted technically feasible with all the materials tested. The olivine, a neo-silicate of Fe and Mg with an olive-green colour, has proven to be a good candidate to act as a bed catalyst for tar removal during gasification of polyolefin plastic wastes. Thanks to its catalytic activity it is possible to obtain very high fractions of hydrogen in the syngas (between 20% and 30%), even using air as the gasifying agent, i.e. in the most favourable economical conditions and with the simplest plant and reactor configuration. The catalytic activity of olivine was instead reduced or completely inhibited when waste-derived fuels from municipal solid wastes and aggregates of different post-consumer plastic packagings were fed. Anyhow, these materials have given acceptable performance, yielding a syngas of sufficient quality for energy applications after an adequate downstream cleaning. © 2010 Elsevier Ltd.

The effect of fuel composition on gasification process performance was investigated by performing mass and energy balances on a pre-pilot scale bubbling fluidized bed reactor fed with mixtures of plastic waste, wood, and coal. The fuels containing plastic waste produced less H 2 , CO, and CO 2 and more light hydrocarbons than the fuels including biomass. The lower heating value (LHV) progressively increased from 5.1 to 7.9 MJ/Nm 3 when the plastic waste fraction was moved from 0% to 100%. Higher carbonaceous fines production was associated with the fuel containing a large fraction of coal (60%), producing 87.5 g/kg Fuel compared to only 1.0 g/kg Fuel obtained during the gasification test with just plastic waste. Conversely, plastic waste gasification produced the highest tar yield, 161.9 g/kg Fuel , while woody biomass generated only 13.4 g/kg Fuel . Wood gasification showed a carbon conversion efficiency (CCE) of 0.93, while the tests with two fuels containing coal showed lowest CCE values (0.78 and 0.70, respectively). Plastic waste and wood gasification presented similar cold gas efficiency (CGE) values (0.75 and 0.76, respectively), while that obtained during the co-gasification tests varied from 0.53 to 0.73.

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 a product or service. It is generally considered the best environmental management tool that can be used to move from a generic statement about the environmental benefit of a given recycling or disposal system to reach an objective quantification of its environmental sustainability. In this study, it is used to assess and compare the environmental performances of three alternative options (landfilling, recycling, and combustion with energy recovery) that could be used in Italy to manage paper and board packaging waste. The results confirm that material recycling may not be the best environmental option. In this specific case, they show that paper use should be viewed in the context of the international trade in biofuels.

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 developed to estimate the time concentration of ammonia profile after a release inside an enclosure. It was used to minimise the amount of releasable ammonia by the insertion of automatic valve devices along the pipe containing pressurized ammonia. The approach for outdoor accidents led to the design of a fluid curtain capable of intercepting and absorbing the released ammonia cloud. Another specific model, which takes into account the two-phase character of an ammonia cloud, was devised in order to calculate the water flow rate needed to ensure adequate absorption efficiency. © 2003 Elsevier Science Ltd. All rights reserved.

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 the successive quantification of probability of occurrence of the different potential Top Events. The results indicated that Recursive Operability Analysis can be usefully applied in the design as well as in the commissioning and in the start-up stages of the plant construction. The quantification of the actual effects of the implementation of new management criteria and design solutions can also be easily obtained. © 2007 Elsevier Ltd. All rights reserved.

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 disposal and follows each activity from the extraction of raw materials to the return of wastes to the ground (cradle-to-grave approach). The study refers to the whole Italian system for recycling of household plastic packaging wastes. The aim was to quantify the overall environmental performances of mechanical recycling of plastic containers in Italy and to compare them with those of conventional options of landfilling or incineration and of a couple of innovative processes of feedstock recycling, low-temperature fluidized bed pyrolysis, and high-pressure hydrogenation. The results confirm that recycling scenarios are always preferable to those of nonrecycling. They also highlight the good environmental performance of new plastic waste management schemes that couple feedstock and mechanical recycling processes. © 2005 American Institute of Chemical Engineers Environ Prog, 2005

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 obtain an objective quantification of all the environmental impacts related with different solid waste management scenarios. In this study, it is used to assess the environmental performance of alternative solid waste management options that could be used in an area of the South of Italy suffering from a situation of weighty solid waste emergency. The extreme delicacy of the decision-making process to which the results have to contribute suggested increasing the reliability of the assessment conclusions by using a high quality of data and a deepened analysis of technical processes. An analytical comparison between three selected scenarios is reported with reference to some crucial environmental impact categories. The results quantify the relative advantages and disadvantages of different management schemes and suggest some possible improvements in design and operating criteria. © 2003 Elsevier B.V. All rights reserved.

Goal, Scope and Background. The object of the study is the Italian system of plastic packaging waste recycling, active until 2001, that collected and mechanically recycled the post-consumer PE and PET liquid containers. The phases of collection, compaction, sorting, reprocessing and refuse disposal were individually analysed and quantified in terms of energy and material consumptions as well as of emissions in the environment. The work is the result of a joint research project with the Italian Consortium for Packaging (CONAI), carried out in co-operation with the main Italian companies active in the field. The main aim was the quantification of the real advantage of plastic container recycling and the definition of criteria, at the same time environmentally compatible and economically sustainable, for their management. Main Features. For each of the unit processes, and in order to increase the data quality, all the data of interest were collected during technical visits to several selected plants active in Italy or deduced by official documents and certificate declarations of the same companies. To allow comparison of resource consumption and environmental pollution from different management scenarios producing different products, the basket of products method was applied. Results. The results indicates that the production of 1 kg of flakes of recycled PET requires a total amount of gross energy that is in the range of between 42 and 55 MJ, depending on whether the process wastes (mainly coming from sorting and reprocessing activities) were sent or not to the energy recovery. The same quantity of virgin PET requires more than 77 MJ. The energetic (and then environmental) saving is so remarkable, even for PE, being 40-49 MJ for the recycled polymer and about 80 MJ that for the virgin polyolefin. The calculations were made with the reasonable assumption that the final utilisation can use the virgin or the recycled polymer without any difference. Conclusions and Outlook. The analysis defined and verified a suitable tool in the field, based on objective data, for comparing different coherent scenarios of waste management politics. This allows one to propose the extension of the tool under different collection schemes, as well as for different systems of packaging recycling. As an immediate consequence of the success of the present study, the joint-research programme with CONAI has been extended for another three years. The focus will be the Italian system for paper and paperboard recycling and that for all plastic packagings. In parallel, a different study has been scheduled with reference to the integrated solid waste management of the Regione Campania, the largest and most populated area in the South of Italy.