LCA of food waste management in Italy, with a special focus on the effect of the bags used for the collection

More than 7 million tonnes of organic fraction were separately collected in Italy in 2018, following a robust increasing trend. Its treatment is progressively shifting towards anaerobic digestion instead of composting, with about 3 million tonnes currently being processed in integrated anaerobic/aerobic treatment plants or in purely anaerobic ones. The type of bag used for the organic waste collection is crucial in determining the overall performance of the system, since there is a mounting evidence that bioplastic bags, especially in the form of shoppers, might cause problems during the anaerobic treatment. On the other hand, paper bags allow for a smoother operation of the plant, since they don’t need to be removed upstream. This project aims to analyse the environmental performances of the full treatment chain of the organic waste processed with anaerobic digestion, starting from the assessment of the weight losses during the household storage, and considering the different behaviour of the bags at the treatment plant. In particular, the degradation potential and the corresponding biomethane production of the different typologies of bag were evaluated at the laboratory level, by means of BMP (Biochemical Methane Potential) tests carried out under different conditions. To assess the performances of the overall organic waste treatment chain, a comparative Life Cycle Assessment for the different types of collection bag (paper bags, bioplastic bags dedicated to the food waste collection, bioplastic shopper bags that can be reused for the food waste collection) was carried out. The following stages were included: the production and supply of raw materials used for the manufacturing of the collection bags and their packaging, the bags production, their distribution, their use at the household, and the collection and treatment of the food waste. As regards the latter, an anaerobic digestion process followed by post-composting was considered, including the valorization of useful outputs and the management of residues. For the recycling and recovery processes, two different modelling approaches were considered: the Circular Footprint Formula applied to Product Environmental Footprint (PEF) studies and the approach applied in the framework of the International Environmental Product Declaration (EPD) System. The results revealed how the use of paper bags for the storage of food waste generally leads to improvements in the impact associated to its overall management, but this is strongly affected by the different approaches in modeling systems where recycling occurs. As regards the impact contributions, the most impacting phases in the overall system are the bag production (for bioplastic) and the food waste collection. The analysis allowed also to state that shopper bags are less impacting than dedicated bioplastic bags because they are utilized, as the first purpose, for carrying the grocery shopping. Please click Additional Files below to see the full abstract. Please click Download on the upper right corner to see the presentation

A hybrid passive cooling wall system: concept and laboratory testing results

The research unit associated to the Laboratory Systems for Technology Innovation (LaSTIn) of the Department of Architecture and Design as well as the Department of Energy, Polytechnic University of Turin, has investigated the possibility of producing a modular wall system for hybrid/natural passive cooling. This system uses pressure differences typical of natural air movements and it is conceived as a mean to reach a quasi-zero-energy building as foreseen by Dir. 2010/31/EU by 2020 for new constructions. In addition, it realises a high level of technological and architectural integration in building constructions. The research focuses on passive and solar cooling techniques and studies the following possible systems, designed and tested separately in laboratory: a) latent heat adsorption cells including silica gel and zeolites for controlling the specific air humidity content, with heat regeneration by a vacuum water solar collectors system; b) a low-pressure heat exchanger, with crossing flows through ducts of rectangular section, to recover sensible heat/cold from return air; c) a passive evaporative cooling element. This paper present the design concept of the wall system as well as a first series of results from laboratory testing regarding the latent heat absorption component

Life Cycle Assessment and economic evaluation of the recovery of materials in an urban waste management system

The main aim of this study was to perform a Life Cycle Assessment (LCA) as well as an economic evaluation of the recovery of recyclable materials in an urban waste management system. Urban waste is mainly composed of three fractions: 1) putrescible materials, 2) recyclables materials, and 3) residual waste. The putrescible materials have to be collected separately and sent to composting and/or anaerobic digestion plants. The recyclables materials have to be sorted and sent to the proper industrial facilities. Finally, the residual waste could be further selected to be sent to energy recovery plants. If citizens separate erroneously urban waste fractions, they produce both environmental and economic damages. In fact, on the base of the Extended Producer Responsibility (EPR), a municipality receives an economic amount for each kilogram of packaging waste collected. In Italy, this activity is managed by CONAI (a private system, created and designed by companies). The “CONAI system” is based on the activities of six consortia each dedicated to promoting and control the most used materials in the packaging production i.e. steel, aluminum, paper, wood, plastics and glass. Packaging waste that goes into the dry residue represents an economic damage (a loss of the “CONAI contribution” and the payment of the disposal fees) as well as an environmental burden. The environmental and economic evaluation was performed for the case study of Nola (39.19 km², 34.349 inhabitants, and 876.47 ab./km²) in the Province on Naples, in the Campania Region of Southern Italy. Nola has a kerbside system which assured a percentage of separate collection of 61% in 2015. The LCA analysis included the treatment and disposal phases as well as the collection and transport phases. The LCA software tool SimaPro and the following three impact assessment methods were used: ReCiPe 2008 (for the medium-term perspective Hierarchist both for midpoint and endpoint levels), Ecological footprint, and IPCC 2013 (100 years). The environmental (Figure 1a) and economic (Figure 1b) analysis were developed for several real and hypothetical scenarios based on increasing percentages of separate collection and different composition analyses of the residual waste (RW). The obtained results confirmed that recovering materials from residual waste is a benefits both in environmental and economic terms. Finally, it is also a social potential benefit because the municipality could invest the economic saving in environmental campaigns entrusted to young people in an area with a high rate of youth unemployment. Please click Additional Files below to see the full abstract

Modal analysis and condition monitoring for an electric motor through MEMS accelerometers

Piezoelectric accelerometers are commonly employed for diagnosing machine faults, due to their accuracy. In the last few years, however, MEMS (Micro Electro-Mechanical Systems) accelerometers have attracted strong interest thanks to their low cost. In this work, a synchronous electric motor with an integrated MEMS sensor is studied and results are compared from both MEMS and piezoelectric sensors. A modal analysis is performed, using data from all available sensors. Comparing the frequency response functions and the natural frequencies shows the limitations of the MEMS sensor. One can then correct the MEMS measurements, by using global statistical parameters calculated on the data or by defining a “filter” function between the signals, thus improving the signal-to-noise ratio. It is found that MEMS sensors may replace piezoelectric ones for diagnostic applications. This way, an inexpensive measurement system (which needs to be calibrated only once, before installation, against higher-accuracy sensors) can be used for vibration monitoring of electric motors

Combining Thermodynamics-based Model of the Centrifugal Compressors and Active Machine Learning for Enhanced Industrial Design Optimization

The design process of centrifugal compressors requires applying an optimization process which is computationally expensive due to complex analytical equations underlying the compressor's dynamical equations. Although the regression surrogate models could drastically reduce the computational cost of such a process, the major challenge is the scarcity of data for training the surrogate model. Aiming to strategically exploit the labeled samples, we propose the Active-CompDesign framework in which we combine a thermodynamics-based compressor model (i.e., our internal software for compressor design) and Gaussian Process-based surrogate model within a deployable Active Learning (AL) setting. We first conduct experiments in an offline setting and further, extend it to an online AL framework where a real-time interaction with the thermodynamics-based compressor's model allows the deployment in production. ActiveCompDesign shows a significant performance improvement in surrogate modeling by leveraging on uncertainty-based query function of samples within the AL framework with respect to the random selection of data points. Moreover, our framework in production has reduced the total computational time of compressor's design optimization to around 46% faster than relying on the internal thermodynamics-based simulator, achieving the same performance.Comment: Accepted after peer-review at the 1st workshop on Synergy of Scientific and Machine Learning Modeling, SynS & ML ICML, Honolulu, Hawaii, USA. July, 2023. Copyright 2023 by the author(s

A European Researchers’ Night project on mechanical vibrations for high school students

The present works were conceived to be exhibited during the 2022 European Researchers’ Night (ERN 2022), at the University of Modena and Reggio Emilia. The idea is to illustrate the key concepts of mechanical vibration through the use of 3D models and virtual simulation analysis. The paper is directed to high school students planning to enroll in a mechanical engineering bachelor’s degree, in order to approach or consolidate some fundamental concepts of mechanical vibration. Topics not easy to explain, such as the natural frequencies of a body, could be presented more effectively using physical models. Mathematical formalism will be kept to a minimum, as it is beyond the scope of this paper