How does plastic compare with alternative materials in the packaging sector? A systematic review of LCA studies.

In the recent years, packaging made of conventional plastics has been increasingly replaced by materials believed to be more sustainable. However, perceived sustainability must align with scientific assessments, such as life cycle assessments (LCAs). This review analysed 53 peer-reviewed studies published in the time range 2019-2023, aiming at understanding the state of the art in LCA about the environmental impacts of packaging by focusing on the comparison between plastics and alternative materials. The literature showed that consumer perceptions often differ from LCA findings and revealed that, frequently, conventional plastics are not the least environmentally friendly choice. Bioplastics typically show benefits only in the climate change and the fossil resource depletion impact categories. The heavy weight of glass turns out to affect its environmental performances with respect to the light plastics, with reuse being an essential strategy to lower the burdens. The comparison between plastics and metals is more balanced, leaning more towards plastics for food packaging. Similarly, paper resulted often preferable than plastics. Finally, for the other materials (i.e. wood and textiles), the picture is variable. To be competitive with plastics, the alternative materials require improvements like the optimisation of their production processes, their reuse and enhanced end-of-life options. At the same time, recycled polymers could boost the eco-performance of virgin plastics.

Evaluation of the anaerobic degradation of food waste collection bags made of paper or bioplastic.

The amount of compostable bioplastics collected with the food waste is constantly growing, particularly due to the bags used for collection. According to the Italian legislation, compostable bioplastics must be accepted by all biological treatment plants, including aerobic and anaerobic facilities. Anyway, the compostability standard requires only the assessment of the aerobic degradability, while it is generally not required to test the behaviour under anaerobic conditions. This aspect is evaluated in the paper, where the anaerobic degradability of bioplastic bags used for the food waste collection is assessed. First, Biochemical Methane Potential (BMP) tests were performed on four commercial types of bioplastic bags, including those designed only for the collection of food waste and the shoppers, that can be reused for the same purpose. Subsequently, an innovative approach for this kind of substrate was applied, subjecting two bags to semi-continuous co-digestion tests together with the food waste. Both tests were performed by comparing the behaviour of bioplastic bags with that of an alternative collection paper bag. Finally, tests to evaluate the influence of physical phenomena on the degradation of bioplastics were performed to better understand the results of biological tests. BMP tests indicated a good degradability (>71%) of bioplastic bags, while semi-continuous tests showed a much lower degradability (<27%), confirmed by the observation of the undigested bag pieces. On the contrary, the paper bag presents interesting characteristics, because its degradability in the semi-continuous tests (82%) resulted even higher than that observed in the BMP tests (74%). These results highlight an important difference between the bags mono-digestion by means of BMP tests and the semi-continuous co-digestion tests with food waste, which better simulate the full-scale operational conditions.

Life cycle assessment of the food waste management with a focus on the collection bag.

The organic fraction (mainly food waste) is typically the most abundant of the separately collected waste streams. The research aims at investigating the influence of different types of collection bag on the environmental performances of the food waste management chain in Italy. A comparative life cycle assessment (LCA) between two alternative systems based on paper or bioplastic collection bags was carried out. It included the collection bags manufacturing and distribution, their use at the household, the transportation of collected food waste and its subsequent anaerobic digestion, including the valorisation of useful outputs and the management of residues. The two systems were modelled mainly with primary data related to the current management system and to tests performed on bags. The LCA was performed with two different modelling approaches applied in the environmental product declaration (EPD) system and in the product environmental footprint (PEF) studies, respectively. In the scenario representing the average conditions, higher environmental impacts are shown by the use of bioplastic bags compared to paper ones with the EPD approach (+257%/+576%). With the PEF approach, the differences between the two systems are lower (-55%/+133%). Moreover, paper bags could allow for further impact reductions assuming a decrease of the food waste collection frequency, allowed by higher weight losses and a lower generation of leachate and odour during the household storage.

Packaging waste prevention in the distribution of fruit and vegetables: An assessment based on the life cycle perspective.

In recent years, alternative food supply chains based on short distance production and delivery have been promoted as being more environmentally friendly than those applied by the traditional retailing system. An example is the supply of seasonal and possibly locally grown fruit and vegetables directly to customers inside a returnable crate (the so-called 'box scheme'). In addition to other claimed environmental and economic advantages, the box scheme is often listed among the packaging waste prevention measures. To check whether such a claim is soundly based, a life cycle assessment was carried out to verify the real environmental effectiveness of the box scheme in comparison to the Italian traditional distribution. The study focused on two reference products, carrots and apples, which are available in the crate all year round. An experience of a box scheme carried out in Italy was compared with some traditional scenarios where the product is distributed loose or packaged at the large-scale retail trade. The packaging waste generation, 13 impact indicators on environment and human health and energy consumptions were calculated. Results show that the analysed experience of the box scheme, as currently managed, cannot be considered a packaging waste prevention measure when compared with the traditional distribution of fruit and vegetables. The weaknesses of the alternative system were identified and some recommendations were given to improve its environmental performance.

Packaging waste prevention activities: A life cycle assessment of the effects on a regional waste management system.

A life cycle assessment was carried out to evaluate the effects of two packaging waste prevention activities on the overall environmental performance of the integrated municipal waste management system of Lombardia region, Italy. The activities are the use of refined tap water instead of bottled water for household consumption and the substitution of liquid detergents packaged in single-use containers by those distributed 'loose' through self-dispensing systems and refillable containers. A 2020 baseline scenario without waste prevention is compared with different waste prevention scenarios, where the two activities are either separately or contemporaneously implemented, by assuming a complete substitution of the traditional product(s). The results show that, when the prevention activities are carried out effectively, a reduction in total waste generation ranging from 0.14% to 0.66% is achieved, corresponding to a 1-4% reduction of the affected packaging waste fractions (plastics and glass). However, the improvements in the overall environmental performance of the waste management system can be far higher, especially when bottled water is substituted. In this case, a nearly 0.5% reduction of the total waste involves improvements ranging mostly between 5 and 23%. Conversely, for the substitution of single-use packaged liquid detergents (0.14% reduction of the total waste), the achieved improvements do not exceed 3% for nearly all impact categories.

Life cycle assessment applications to reuse, recycling and circular practices for textiles: A review.

To understand which are the best strategies for textile waste management and to analyse the effects on the environment of applying circular economy practices to textile products, a review of 45 publications where life cycle assessment (LCA) is applied to these topics has been carried out. The separate collection of textiles, followed by reuse and recycling brings relevant environmental benefits, with impacts related to reuse resulting lower than those of recycling. At the opposite, when mixed municipal solid waste is addressed to energy recovery, the textile fraction is the second most impacting on climate change, right after plastics, while for landfill disposal impacts textiles directly follow the more biodegradable fractions. Textiles manufacturing using recycled fibres generally gives lower impacts than using virgin ones, with a few exceptions in some impact categories for cotton and polyester. The circular practices with the lowest impacts are those that ensure the extension of the textiles service life. Another aim of this review is to identify the main variables affecting the life cycle impact assessment (LCIA). These resulted to be the yield and material demand of recycling processes, the use phase variables, the assumptions on virgin production replaced by reuse or recycling, the substitution factor in reuse, and transportation data in business models based on sharing. Thus, in LCA modelling, great attention should be paid to these variables. Future research should address these aspects, to acquire more relevant data, based on industrial-scale processes and on people habits towards the circular economy strategies applied to textiles.

Life cycle assessment and cost analysis of an innovative automatic system for sorting municipal solid waste: A case study at Milan Malpensa airport.

With the recent advancement in artificial intelligence, there are new opportunities to adopt smart technologies for the sorting of materials at the beginning of the recycling value chain. An automatic bin capable of sorting the waste among paper, plastic, glass & aluminium, and residual waste was installed in public areas of Milan Malpensa airport, a context where the separate collection is challenging. First, the airport waste composition was assessed, together with the efficiency of the manual sorting performed by passengers among the conventional bins: paper, plastic, glass & aluminium, and residual waste. Then, the environmental (via the life cycle assessment - LCA) and the economic performances of the current system were compared to those of a system in which the sorting is performed by the automatic bin. Three scenarios were evaluated: i) all waste from public areas, despite being separately collected, is sent to incineration with energy recovery, due to the inadequate separation quality (S0); ii) recyclable fractions are sent to recycling according to the actual level of impurities in the bags (S0R); iii) fractions are sorted by the automatic bin and sent to recycling (S1). According to the results, the current separate collection shows a 62 % classification accuracy. Focusing on LCA, S0 causes an additional burden of 12.4 mPt (milli points) per tonne of waste. By contrast, S0R shows a benefit (-26.4 mPt/t) and S1 allows for a further 33 % increase of benefits. Moreover, the cost analysis indicates potential savings of 24.3 €/t in S1, when compared to S0.

Degradation of paper-based boxes for food delivery in composting and anaerobic digestion tests.

This study evaluated the fate of food delivery boxes when subjected to biological treatments, reproducing at the lab-scale the conditions of full-scale plants. Four paper-based boxes were composted: two made of paper only, one coupled with polylactic acid (PLA), and one with a barrier coating. One paper only box and the box with PLA were also investigated for their anaerobic degradability with biochemical methane potential (BMP) and semi-continuous tests. During composting, the boxes were not recognisable inside the compost after four (paper only boxes), eight (box with PLA), and twelve (box with barrier coating) weeks. In BMP tests, the paper only box showed a degradability similar to that of food waste (92 %), while the box with PLA degraded only at 76 %. Furthermore, undigested pieces of PLA were found in semi-continuous tests. Accordingly, paper resulted suitable for biological treatments, while the presence of PLA or other barrier coatings can be critical.

Aluminium recovery from waste incineration bottom ash, and its oxidation level.

The recovery of aluminium (Al) scraps from waste incineration bottom ash is becoming a common practice in waste management. However, during the incineration process, Al in the waste undergoes oxidation processes that reduce its recycling potential. This article investigates the behaviour of Al scraps in the furnace of two selected grate-fired waste-to-energy plants and the amount recoverable from the bottom ash. About 21-23% of the Al fed to the furnace with the residual waste was recovered and potentially recycled from the bottom ash. Out of this amount, 76-87% was found in the bottom ash fraction above 5 mm and thus can be recovered with standard eddy current separation technology. These values depend on the characteristics and the mechanical strength of the Al items in the residual waste. Considering Al packaging materials, about 81% of the Al in cans can be recovered from the bottom ash as an ingot, but this amount decreases to 51% for trays, 27% for a mix of aluminium and poly-laminated foils and 47% for paper-laminated foils. This shows that the recovery of Al from the incineration residues increases proportionally to the thickness of the packaging.

Improving integrated waste management at the regional level: the case of Lombardia.

The article summarises the main results of the 'Gestione Rifiuti in Lombardia: Analisi del ciclo di vita' (Waste management in Lombardia region: Life cycle assessment; GERLA) project. Life cycle assessment (LCA) has been selected by Regione Lombardia as a strategic decision support tool in the drafting of its new waste management programme. The goal was to use the life cycle thinking approach to assess the current regional situation and thus to give useful strategic indications for the future waste management. The first phase of the study consisted of the LCA of the current management of municipal waste in the Lombardia region (reference year: 2009). The interpretation of such results has allowed the definition of four possible waste management scenarios for the year 2020, with the final goal being to improve the environmental performance of the regional system. The results showed that the current integrated waste management of Lombardia region is already characterised by good energy and environmental performances. However, there is still room for further improvement: actions based, on the one hand, on a further increase in recycling rates and, on the other hand, on a series of technological modifications, especially in food waste and residual waste management, can be undertaken to improve the overall system.

LCA of waste prevention activities: a case study for drinking water in Italy.

The strategic relevance of waste prevention has considerably increased worldwide during recent years, such that the current European legislation requires the preparation of national waste prevention programmes in which reduction objectives and measures are identified. In such a context, it is possible to recognise how, in order to correctly evaluate the environmental consequences of a prevention activity, a life cycle perspective should be employed. This allows us to go beyond the simple reduction of the generated waste which, alone, does not automatically imply achieving better overall environmental performance, especially when this reduction is not pursued through the simple reduction of consumption. In this study, the energetic and environmental performance of two waste prevention activities considered particularly meaningful for the Italian context were evaluated using life cycle assessment (LCA) methodology. The two activities were the utilisation of public network water (two scenarios) and of refillable bottled water (two scenarios) for drinking purposes, instead of one-way bottled water (three scenarios). The energy demand and specific potential impacts of the four waste prevention scenarios and of the three baseline scenarios were compared with the aim of evaluating whether, and under what conditions, the analysed prevention activities are actually associated with overall energetic and environmental benefits. In typical conditions, the use of public network water directly from the tap results in the best scenario, while if water is withdrawn from public fountains, its further transportation by private car can involve significant impacts. The use of refillable PET bottled water seems the preferable scenario for packaged water consumption, if refillable bottles are transported to local distributors along the same (or a lower) distance as one-way bottles to retailers. The use of refillable glass bottled water is preferable to one-way bottled water only if a distance beneath 150 km separates bottling plants from local distributors and retailers (except for eutrophication indicator which is always slightly worse). To reduce waste generation and to achieve meaningful potential savings of natural resources, energy and greenhouse gas emissions, a reduction in one-way bottled water consumption in Italy is recommended in favour of the use of public network water and of the establishment of short distance-PET bottles based refilling systems. The development of closed loop recycling of one-way PET bottles, and especially the reduction of the distance along which one-way bottled water is transported, are also important.

Chemical and sewage sludge co-incineration in a full-scale MSW incinerator: toxic trace element mass balance.

Co-incineration of sludges with MSW is a quite common practice in Europe. This paper illustrates a case of co-incineration of both sewage sludges and chemical sludges, the latter obtained from drinking water production, in a waste-to-energy (WTE) plant located in northern Italy and equipped with a grate furnace, and compares the toxic trace elements mass balance with and without the co-incineration of sludges. The results show that co-incineration of sewage and chemical sludges does not result in an increase of toxic trace elements the total release in environment, with the exception of arsenic, whose total release increases from 1 mg t(fuel) (-1) during standard operation to 3 mg t(fuel) (-1) when sludges are co-incinerated. The increase of arsenic release is, however, attributable to the sole bottom ashes, where its concentration is five times higher during sludge co-incineration. No variation is observed for arsenic release at the stack. This fact is a further guarantee that the co-incineration of sludges, when performed in a state-of-the-art WTE plant, does not have negative effects on the atmospheric environment.

The implementation of anaerobic digestion of food waste in a highly populated urban area: an LCA evaluation.

While source separation of waste packaging materials for recycling is well established in several metropolitan areas, the collection of food waste from the households is less widespread because of its more difficult implementation. Source segregation of food waste in densely populated areas is raising new interest, as the availability of biogas following its anaerobic digestion (AD) paves the road to a number of possibilities, from electric energy production to its upgrading to biomethane and subsequent feeding in to the natural gas network or in vehicles as a fuel. The study addresses this waste management option by analysing a real metropolitan situation where food waste currently ends up mixed with the residual waste in a waste-to-energy plant (WTE). We assume to establish a new collection scheme for household food waste, followed by its treatment in a new AD and post-composting facility. A comparative life cycle assessment was carried out, where possible synergies between the existing WTE plant and the new one were evaluated. All new scenarios based on AD attained similar or better results compared with the reference scenario for almost all of the impact indicators. The most robust indication is related to global warming potential, with a potential improvement of up to 37%. Finally, a sensitivity analysis was carried out to assess the effect of the variation of the most relevant parameters. Results have proven to be very sensible to the hypothesis on the type of substituted electric energy. All the other examined sensitivities resulted in variations well below 10%.