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The increase of biowaste generation has reached critical levels in many countries. The European legislation introduced the biowaste treatment and the organic recycling as central theme of its political agenda with the aim to promote the sustainable exploitation of this peculiar waste. The most utilized technologies applied to the biowaste treatment are based on the biological processes targeting to produce biogas or, more recently, biomethane to be used as fuel. The production of biomethane allows to produce a substitute of the fossil methane with a yield of about 0.07gCH4/gbiowaste; the remaining fractions are waste coming from the pretreatment/refining steps, solid digestate or stabilized compost, and leachate. The sustainable treatment of these fractions is a mandatory issue to treat the biowaste in a reliable and sustainable integrated process since their amount is more than 85% and the impact of their treatment on environment and economy of the overall treatment process can be quite relevant. This chapter focused on the so-called smart facility that integrates processes based on thermochemical processes with the biological one targeting to increase the overall sustainability, the flexibility regarding the input biowaste composition, and the independency by the external factors affecting the waste trading.

In this study, the effect of gasifying agent and bed material on the performance of the co-gasification of a mixture of coal, plastic waste, and wood was investigated. The experimental runs were carried out in a lab-scale bubbling fluidized bed reactor utilizing air, oxygen-enriched air, a mixture of air and steam, and a mixture of oxygen and carbon dioxide as reactant gases, while silica sand, olivine, and a mixture of olivine and dolomite as bed materials were used. The results indicated that both gasifying agent and bed material strongly affect the gas composition and, as a consequence, the process performance. In particular, the test with oxygen-enriched air and silica sand provided a producer gas with the highest heating value (9.32 MJ/Nm3), while the best performance in terms of gas yield (2.98 Nm3/kg) and tar reduction (−94.5%) was obtained by utilizing the air/steam mixture and olivine. As regards tar composition, it was observed that the most abundant and recalcitrant tar substance groups are naphthalenes and PAHs. On the other hand, phenols and furans appear to be the most sensitive groups to the effect of gasifying agent and bed material.

The handling of sewage sludge is one of the most significant issues of wastewater treatment plant due to its potential harmful environmental impact and remarkable disposal costs. As a consequence, a proper handling of this biowaste is needed. In the present study, a bench-scale fixed bed gasifier was operated with a sewage sludge coming from a drying facility. The experimental runs have been carried out using for each test 30 g of dried sewage sludge, steam as gasifying agent and by varying the reactor temperature in the range of 700 – 850 °C. The results indicated that the gasification test conducted at a temperature of 700 °C produced the highest concentration of hydrogen, 58.2%. In addition, the increase of reaction temperature determined a reduction of char and tar from 11.4 to 9.7 g and from 9.1 to 0.7 g, respectively. On the other hand, the cold gas efficiency increased from 11 to 50%.

Concentrating Solar Plants (CSP) represent a feasible alternative to fossil fuel driven power plants. Anyway, technical and economic issues severely prevent their large diffusion over the world. In this paper, a numerical investigation is accomplished to predict the performance of a CSP without thermal storage (TES). A stationary, 1-D model of heat transfer fluid (HTF) is presented, taking into account the heat losses occurring along the Heat Collector Element (HCE). A Southern Italy location is considered for the solar plant simulation, and two HTF thermal oils, Therminol VP1 and Therminol 62, are compared in terms of thermal power delivered to the power plant block. HTF temperature distribution and velocity profile along the solar plant are obtained to evaluate the performance of a coupled Organic Rankine Cycle (ORC) plant, simulated using the DWSIM programme, emphasizing the differences when using three different types of working fluids, i.e. wet, dry and isentropic.

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 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.

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.