Indicators and characteristics of PET packaging collected in a Deposit and Refund System pilot project.

Countries that have a Deposit and Refund System (DRS) show high rates of selective beverage packaging waste collection, indicating that it is a powerful economic instrument for achieving the European packaging recycling targets. DRS ensure that collected material is of a sufficiently high quality to be incorporated into new products. In Portugal, the Government has decided to implement a DRS for non-reusable beverage packaging as a strategy to increase the packaging recycling rate, which is currently considerably lower than the mandatory European targets. To acquire knowledge and experience for the design and implementation of the future DRS, a pilot project was carried out with polyethylene terephthalate (PET) beverage packaging, using 23 Reverse Vending Machines (RVM) installed at supermarkets across mainland Portugal. The authors monitored the DRS pilot project between March 2020 and December 2022. The main objectives were to determine operational indicators and evaluate the characteristics and quality of the PET deposited, using both the data recorded by the RVM and a characterisation of the packages contained in a sample of 46 bags. The results provided important data for planning the Portuguese strategy, which may also support operational or political decisions in countries in similar contexts. Whilst the recycling plants that received the material collected in these RVM confirmed that its quality allows for the production of PET food-grade flakes, this research identified a need to improve the design of packaging and to communicate this with producers, to better allow for the incorporation of recycled material into food beverage packaging.

Ecotoxicity effect factors for plastic additives on the aquatic environment: a new approach for life cycle impact assessment.

All plastic contains additives. Once in the environment, these will start to leach out and will expose and harm aquatic biota, causing potentially lethal and sub-lethal toxic effects. Even though life cycle assessment covers the toxic impacts of several thousands of chemicals, models to assess the toxic impacts of plastic additives are only emerging. We gathered 461 data points from the literature (266 for freshwater and 195 for marine ecosystems) for 75 species belonging to 9 different phyla. The endpoints effective concentration and lethal concentration, no observed effects concentrations and lowest observed effect concentration tested in acute and chronic exposure, were harmonized into chronic values by applying extrapolation factors. The collected data points covered 75 main plastic additives. This allowed us to calculate 25 Effect factors, 19 for single chemicals and four for overarching categories (alkylphenols, benzophenones, brominated flame retardants and phosphates. In addition, we calculated an aggregated effect factor for chemicals that did not fit in any of the previous groups, as well as a Generic effect factor including 404 gathered data points. The estimated potentially affected fraction (PAF) for the single additives varied between 20.69 PAF·m3·kg-1 for diethyl phthalate and 11081.85 PAF·m3·kg-1 for 4-Nonylphenol. The factors can in future be combined with fate and exposure factors to derive a characterization factor for toxicity caused by additives in aquatic species. This is an important advancement for the assessment of the impacts of plastic debris on aquatic species, thus providing information for decision-makers, as well as guiding policies for the use of additives, ultimately aiming to make the plastic value chain more sustainable.

Effects of landfill age, climate, and size on leachate from urban waste landfills in Portugal: A statistics and machine learning analysis.

The leachate generated by in urban waste landfills can cause environmental pollution if not controlled and treated. With different proportions of biodegradable waste, urban waste degrades over several phases in anaerobic conditions within a landfill. Using multivariate leachate data from 32 engineered landfills in Portugal, each with a similar waste composition, and all classified as non-hazardous waste landfills receiving urban waste, statistical inference was applied to categorise and deduce significant statistical differences in leachate volume and quality between landfill age, size, and climate, as well as the interactions and effects within these categories. The findings show that the effects of size and age on the leachate volume are prevalent over local, Mediterranean climate conditions; in larger landfills, waste may not be degrading as efficiently as in medium-sized landfills; hotter zones showed higher levels of COD and lower levels of BOD5 than warmer zones, indicating increased biological activity under higher temperature conditions; TN and NH4-N increase significantly with age and size; Cl- also significantly increases with age, showing higher levels, along with SO42-, in hotter zones as well as a concentration effect in the dry season, along with K+; heavy metals maintain levels as landfills age from intermediate to old, with only Cd2+ and Pb2+ showing significant reductions. High correlations between macro inorganics and between heavy metals were found. Cluster analysis showed two main branches, one representing the initial to intermediate stages of anaerobic degradation, and the other the interactions between leaching parameters in the later methanogenic phase of landfill stabilisation.

Strategies to promote construction and demolition waste management in the context of local dynamics.

Achieving a broad analysis of construction and demolition waste (CDW) management without considering local scale dynamics, and its detailed characteristics, is a constraint that has made it challenging to optimally engage in an integrated assessment of the circular economy principles in the construction sector. In this sense, this research demonstrates that investing in local strategies is important, involving municipalities and micro and small construction companies. Firstly, the results reveal the importance of having controlled sites, under local responsibility, for the preliminary storage of CDW, creating in waste producers the habit of separating waste onsite, reducing costs and limitations for municipalities. Secondly, frequent supervision actions at construction sites are also important at this scale, as they facilitate progress in terms of encouraging compliance with mandatory legal procedures and good practices for CDW management. But it is easier to improve practice through direct onsite procedures than it is with bureaucratic legal requirements alone. Thirdly, procedural control, implemented by municipal technicians in conjunction with other strategies, also helps to promote CDW management, this being associated with processes of public and private construction works subjected to license or prior control, in opposition to what has been accomplished so far. But the research also demonstrated that regular awareness, training, and supervision actions might increase the likelihood of improvements in behaviour on the local scale, in the sense that stakeholders acquire new habits, which, over time, might lead to better results locally and, as a consequence, influence other scales of intervention.

Influence of construction company size on the determining factors for construction and demolition waste management.

Due to the relevance of construction and demolition waste (CDW) generation for circular economy and reduction of environmental impacts, it is important to evaluate the factors leading to constraints regarding waste. Previous researchers have assessed construction company attitudes and behaviors toward CDW management, but factors such as the presence of environmental technicians, registration of the CDW generated, commitment to the legal framework, the subcontracting regime, and construction works' oversight were rarely addressed in terms of the differences existing within the construction sector. Thus, the objective of this research is to evaluate the relationship of these factors with construction company size. A questionnaire was sent to Portuguese construction companies, and 652 responded. The sample was divided into three groups: micro, small, and medium/large companies. Statistical data treatment was carried out to assess whether there were statistically significant differences in the mentioned factors between groups. The main conclusions highlight: the prevalence of environmental technicians working in larger companies; the registration on waste platforms being only performed consistently by medium/large companies; a considerable proportion of micro and small companies having knowledge gaps about the practices adopted; the responsibility for CDW management within the subcontracting regime being mainly from subcontractors; and the presence of a gap regarding onsite construction works oversight. These differences lead to the need to reevaluate the strategies for CDW management and adapt the strategies to the specific conditions of the construction sector, including the size of construction companies.

Waste hierarchy index for circular economy in waste management.

The aim of current European Union waste management directives is to promote prevention of waste and the application of a waste management hierarchy: preparing for reuse, recycling, other recovery, and disposal. The Waste Framework Directive only measures the waste operations recycling, incineration, and landfill individually, not measuring the implementation of the waste hierarchy principle in Member States of the European Union. The present study proposes a waste hierarchy index (WHI) to measure the waste hierarchy within a circular economy context, applied to municipal solid waste. In developing the WHI, recycling and preparing for reuse, as defined by Eurostat, were considered as positive contributors to the circular economy, and incineration and landfill as negative contributors. The WHI was applied at different geographic scales (local and national levels) to verify its potential and limitations. The WHI is a direct and concise indicator that provides a holistic perspective on how waste is being managed. The WHI is more than a source of waste statistics; it is the beginning of a real discussion about how waste statistics should be managed to reach a circular economy through the implementation of waste hierarchy.

Solid waste prevention and management at green festivals: A case study of the Andanças Festival, Portugal.

Research on waste prevention and management at green festivals is scarce. The present study helps to fill this gap by analyzing waste prevention/reduction and management measures implemented at the Andanças festival, Portugal. Waste characterization campaigns and a questionnaire survey were conducted during the festival. The results show that the largest amount of waste generated was residual waste, followed by food and kitchen waste and packaging waste. The amount of waste generated per person per day at the festival was lower than that of other festivals for both the entire venue and the canteen. Concerning food and kitchen waste generated at the canteen, the amounts are in accordance with the findings of previous studies, but the amount of the edible fraction is comparatively low. Source separation rates are high, in line with other festivals that engage in food-waste source separation. Factors affecting the participation of attendees in waste prevention measures at the festival are the type of participant, their region of origin, the frequency of visits, and whether they are attending as a family. Efforts must be made to increase the awareness of attendees about waste prevention measures, to develop guidelines and methods to quantify the waste prevention measures, and to formulate policies aimed at increasing the application of the zero-waste principle at festivals.

A case study of packaging waste collection systems in Portugal - Part I: Performance and operation analysis.

The need to increase packaging recycling rates has led to the study and analysis of recycling schemes from various perspectives, including technical, economic, social, and environmental. This paper is part one of a three-part study devoted to comparing two recyclable packaging waste collection systems operating in western Portugal: a mixed collection system, where curbside and drop-off collections are operated simultaneously (but where the curbside system was introduced after the drop-off system), and an exclusive drop-off system. This part of the study focuses on analyzing the operation and performance of the two waste collection systems. The mixed collection system is shown to yield higher material separation rates, higher recycling rates, and lower contamination rates compared with the exclusive drop-off system, a result of the curbside component in the former system. However, the operational efficiency of the curbside collection in the mixed system is lower than the drop-off collection in the mixed system and the exclusive drop-off system, mainly because of inefficiency of collection. A key recommendation is to ensure that the systems should be optimized in an attempt to improve performance. Optimization should be applied not only to logistical aspects but also to citizens' participation, which could be improved by conducting curbside collection awareness campaigns in the neighborhoods that have a mixed system.

The Portuguese plastic carrier bag tax: The effects on consumers' behavior.

Marine litter from lightweight plastic bags is a global problem that must be solved. A plastic bag tax was implemented in February 2015 to reduce the consumption of plastic grocery bags in Portugal and in turn reduce the potential contribution to marine litter. This study analyzes the effect of the plastic bag tax on consumer behavior to learn how it was received and determine the perceived effectiveness of the tax 4months after its implementation. In addition, the study assessed how proximity to coastal areas could influence behaviors and opinions. The results showed a 74% reduction of plastic bag consumption with a simultaneously 61% increase of reusable plastic bags after the tax was implemented. Because plastic bags were then reused for shopping instead of garbage bags, however, the consumption of garbage bags increased by 12%. Although reduction was achieved, the tax had no effect on the perception of marine litter or the impact of plastic bags on environment and health. The majority of respondents agree with the tax but view it as an extra revenue to the State. The distance to the coast had no meaningful influence on consumer behavior or on the perception of the tax. Although the tax was able to promote the reduction of plastics, the role of hypermarkets and supermarkets in providing alternatives through the distribution of reusable plastic bags was determinant to ensuring the reduction.

A case study of packaging waste collection systems in Portugal - Part II: Environmental and economic analysis.

An understanding of the environmental impacts and costs related to waste collection is needed to ensure that existing waste collection schemes are the most appropriate with regard to both environment and cost. This paper is Part II of a three-part study of a mixed packaging waste collection system (curbside plus bring collection). Here, the mixed collection system is compared to an exclusive curbside system and an exclusive bring system. The scenarios were assessed using life cycle assessment and an assessment of costs to the waste management company. The analysis focuses on the collection itself so as to be relevant to waste managers and decision-makers who are involved only in this step of the packaging life cycle. The results show that the bring system has lower environmental impacts and lower economic costs, and is capable of reducing the environmental impacts of the mixed system. However, a sensitivity analysis shows that these results could differ if the curbside collection were to be optimized. From economic and environmental perspectives, the mixed system has few advantages.

Composition of plastics from waste electrical and electronic equipment (WEEE) by direct sampling.

This paper describes a direct analysis study carried out in a recycling unit for waste electrical and electronic equipment (WEEE) in Portugal to characterize the plastic constituents of WEEE. Approximately 3400 items, including cooling appliances, small WEEE, printers, copying equipment, central processing units, cathode ray tube (CRT) monitors and CRT televisions were characterized, with the analysis finding around 6000 kg of plastics with several polymer types. The most common polymers are polystyrene, acrylonitrile-butadiene-styrene, polycarbonate blends, high-impact polystyrene and polypropylene. Additives to darken color are common contaminants in these plastics when used in CRT televisions and small WEEE. These additives can make plastic identification difficult, along with missing polymer identification and flame retardant identification marks. These drawbacks contribute to the inefficiency of manual dismantling of WEEE, which is the typical recycling process in Portugal. The information found here can be used to set a baseline for the plastics recycling industry and provide information for ecodesign in electrical and electronic equipment production.

Solid waste management in European countries: a review of systems analysis techniques.

In the past few decades, solid waste management systems in Europe have involved complex and multi-faceted trade-offs among a plethora of technological alternatives, economic instruments, and regulatory frameworks. These changes resulted in various environmental, economic, social, and regulatory impacts in waste management practices which not only complicate regional policy analysis, but also reshape the paradigm of global sustainable development. Systems analysis, a discipline that harmonizes these integrated solid waste management strategies, has been uniquely providing interdisciplinary support for decision making in this area. Systems engineering models and system assessment tools, both of which enrich the analytical framework of waste management, were designed specifically to handle particular types of problems. Though how to smooth out the barriers toward achieving appropriate systems synthesis and integration of these models and tools to aid in the solid waste management schemes prevalent in European countries still remains somewhat uncertain. This paper conducts a thorough literature review of models and tools illuminating possible overlapped boundaries in waste management practices in European countries and encompassing the pros and cons of waste management practices in each member state of the European Union. Whereas the Southern European Union (EU) countries need to develop further measures to implement more integrated solid waste management and reach EU directives, the Central EU countries need models and tools with which to rationalize their technological choices and management strategies. Nevertheless, considering systems analysis models and tools in a synergistic way would certainly provide opportunities to develop better solid waste management strategies leading to conformity with current standards and foster future perspectives for both the waste management industry and government agencies in European Union.