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Packaging represents the largest fraction of plastic waste in Europe. Currently, mechanical recycling schemes are mainly focused on the recovery of rigid packaging (like bottles), while for flexible packaging, also called films, recycling rates remain very low. Existing mechanical recycling technologies for these films are quite basic, especially in the case of complicated post-consumer flexible plastics (PCFP) waste, leading to regranulate qualities that are often subpar for renewed use in demanding film applications. In this study, the technical and economic value of an improved mechanical recycling process (additional sorting, hot washing, and improved extrusion) of PCFPs is investigated. The quality of the four types of resulting regranulates is evaluated for film and injection molding applications. The obtained Polyethylene-rich regranulates in blown films offer more flexibility (45-60%), higher ductility (27-55%), and enhanced tensile strength (5-51%), compared to the conventional mechanical recycling process. Likewise, for injection molded samples, they exhibit more flexibility (19-49%), enhanced ductility (7 to 20 times), and higher impact strength (1.8 to 3.8 times). An economic assessment is made between the obtained increased market value and the capital investment required. It is shown that the economic value can be increased by 5-38% through this improved recycling process. Overall, the study shows that it is possible to increase the mechanical recycling quality of PCFP in an economically viable way, thus opening the way for new application routes and overall increased recycling rates.

Volatile organic compounds (VOCs), including odors, are still a key issue in plastic recycling, especially in case of flexible packaging. Therefore, this study presents a detailed qualitative and quantitative VOC analysis by applying gas chromatography on 17 categories of flexible plastic packaging that are manually sorted from bales of post-consumer flexible packaging (e.g., beverage shrink wrap, packaging for frozen food, packaging for dairy products, etc.). A total of 203 VOCs are identified on packaging used for food products, while only 142 VOCs are identified on packaging used for non-food products. Especially, more oxygenated compounds (e.g., fatty acids, esters, aldehydes) are identified on food packaging. With more than 65 VOCs, the highest number of VOCs is identified on packaging used for chilled convenience food and ready meals. The total concentration of 21 selected VOCs was also higher on packaging used for food products (totally 9187 μg/kg plastic) compared to packaging used for non-food packaging (totally 3741 μg/kg plastic). Hence, advanced sorting of household plastic packaging waste, e.g., via tracer-based sorting or watermarking, could open the door towards sorting on other properties than polymer type, such as mono- versus multi-material packaging, food versus non-food packaging or even their VOC profile, which might allow for tailoring washing procedures. Potential scenarios showed that sorting the categories with the lowest VOC load, which corresponds to half of the total mass of flexible packaging, could result in a VOC reduction of 56%. By producing less contaminated plastic film fractions and by tailoring washing processes recycled plastics can ultimately be used in a broader market segment.

Quality of recycling is a concept used by many authors in the scientific literature and the EU legislator. However, a clear definition of what is intended for quality of recycling and a framework for operationalising it is lacking. Most studies, while proposing indicators reflecting quality, leave the concept of quality largely undefined. Such lack of clarity is an obstacle to the conception of robust policies addressing recycling and circular economy. In this article, we review the available studies investigating on recycling quality, synthetize the approaches available and conclude suggesting a way forward for research to operationalise the definition to support circular economy policy measures and monitoring. Essentially, quality is not an on/off criterion. The definition of quality of recycling should consider that quality depends on technical characteristics of the recyclate, which determine if it is adequate (thus functional) for a certain end application or not. Furthermore, it should consider that the recyclate can be used in different end applications over different markets and that can be adequate for substitution of primary resources in certain applications, but less or not in others. At system-wide level, this results in a certain degree of virgin resource substitution. To this end, preserving functionality, i.e. minimising the recyclate loss of functions via functional recycling, is key. Drawing upon studies on waste management, life cycle assessment and resource dissipation, we link the concept of functionality to substitutability of virgin resources and broader suitability in the circular economy, striving to show the linkages between different perspectives.

Electronics require a complex composition and energy-intensive manufacturing. Yet, most of the world’s waste electrical and electronic equipment is not collected and recycled. Circular economy (CE) strategies can reduce the loss of materials and environmental footprint in electronics. Resource efficiency indicators – typically defined as benefits (handprint) over burdens (footprint) – can measure materials’ life cycle performance. This paper aims to develop resource efficiency indicators that show the benefits and burdens of materials use. We illustrated the indicators with a case study of four materials (aluminium, copper, iron, and plastics) embedded in laptops. The study includes scenarios with different CE strategies: energy recovery, recycling, refurbishing, and reuse. The scenarios show the use of the materials in several cycles of laptops over a 25-year time horizon. Generally, scenarios with cycles of refurbishment and reuse showed improved resource efficiency compared to recycling scenarios. Compared to energy recovery the improvement was up to 189% (refurbishment) and 157% (reuse) in the case of aluminium. Nonetheless, it is remarkable that the average resource efficiency results showed a preference for refurbishing over reuse during 25 years. The result is limited to a shorter functional inuse time of reused laptops. This analysis is relevant for a CE, where the value of materials should be kept for as long as possible. Our methodology expands the traditional one-cycle perspective by measuring the use of materials for 25 years. Policy-makers can use our indicators to assess CE strategies for several product cycles that keep materials in use lowering environmental impacts

Our whole society depends on the use of natural resources. Despite the fact that most natural resources are limited, they are not always used in a sustainable way. To monitor the transition towards a more resource efficient society, a wide variety of indicators has been developed over the years, both within a policy context and an industrial context. However, these indicators are not univocally defined, which generates confusion about the real meaning of resource efficiency. Indeed, the term resource efficiency is interpreted in different ways: from the simple accounting of resource extraction to environmental impact assessment related to resource availability and provision of resources ; from the micro-level of products and companies to the macro-level of regions and countries ; from a gate-to-gate perspective to a life cycle perspective or from a national perspective1 to a global perspective . Also the considered resource range (which natural resource types are taken into account) and the used quantification metric (monetary or physical) can vary from indicator to indicator. Another issue is the provenience of resources: in some studies is referred to natural resources, while in others waste is also considered to be a potential resource . This paper tries to bring order into these different visions by proposing a systematized framework for resource efficiency indicators based on LCA practices. The proposed framework is subdivided in multiple levels based on the interpretations summarized above. The use of the framework is illustrated by structuring several resource efficiency indicators in practice today, e.g. the GDP over DMC (Gross Domestic Product over Domestic Material Consumption), used within a policy context, or process-efficiency, used within an industrial context. Within this framework, resource efficiency indicators can be classified and critically evaluated, identifying possibilities for further development and improvement.

At an ever increasing rate innovative chemistry and technology platforms are reshaping manufacturing environments to become factories of the future by being more productive, lean and flexible. The use of Life Cycle Assessment (LCA) in early process development phases has been challenged many a time to assess whether or not this willingness to strive for innovation is an environmentally sustainable one, often due to a lack of process data. This study takes the streamlining of LCA one step further and proposes an optimal complexity of modelled product systems in terms of their optimal set of predictor variables. Out of more than 2,800 Basic Operations (BOs) in pharmaceutical synthesis steps, candidate predictor variables were identified to forecast the environmental burden (in this case natural resource consumption) of a production step per unit of output. By means of backwards stepwise linear regression modelling, combinations of candidate predictors were tested and evaluated based on their predictive power (R²) and the model uncertainty. It was proven that at least the amount of organic solvents used, the molar efficiency and the time duration of the synthesis step should be included in the model (R² = 0.87) as being the most significant predictor variables. Including additional predictors however imposes no guarantee to contribute to the predictive power and eventually weakens the model interpretation and its simplicity. The results of the study were evaluated in the light of the product-specific versus product group approach debate. Should LCAs be generalized to such an extent that an extensively diversified product group is to be represented with an averaged burden, while fairly simplified and streamlined methods can represent product-specific impact assessments with a reasonable need for data, time and knowledge? The trade-off between simplicity and accuracy will be dealt with quantitatively in the oral presentation. Ideally, an organization should be able to derive its environmental impacts from readily available Enterprise Resource Planning (ERP) data, linking supply chains back to the cradle of resource extraction, excluding the need for an approximation with product group averages. While this study has taken a step in that direction, more research should be conducted especially on how efforts towards sustainable development should be addressed with care to valorise them efficiently in the supply chain and its sectors, beyond any company borders.

The natural resource footprint of producing protein rich algal meal for livestock feed applications in The Netherlands was examined. Microalgae were cultivated at pilot scale (500m² open ponds) and integrated in a biorefinery making use of waste heat and flue gases. The final products were electricity, digestate, heat available for a nearby bio-ethanol facility and algal oil and meal. The sustainability of this rather new biomass source for animal feed was compared with the more traditional route of soybean crop production. The soybeans were cultivated, dried and crushed in Brazil and the soy meal, which is commonly used as a protein rich animal feed ingredient, was transported to The Netherlands. An exergy analysis (EA) on the integrated algal biorefinery revealed the process inefficiencies of drying (44.01%) and inoculum production (54.98%). Attributional exergetic life cycle assessment (ELCA) methodology was used to determine the resource footprint of the (algae based) biorefinery and the linear (soybean based) economy. Therefore, the Cumulative Exergy Extraction from the Natural Environment (CEENE) method was used and system expansion was applied to avoid physical allocation. For the biorefinery, especially the digestion process had a big contribution to the total footprint (72.74%), mainly because of the high daily demand for biomass and electricity use of the dosage system. When comparing the resource footprint of algal meal and soy meal production, i.e. a young, small scale technology was compared to a mature large scale technology, a factor 10² difference could be noticed. First results of a sensitivity analysis indicated the importance of a higher areal algae productivity, more use of renewable resources (e.g. wind energy) and decreasing energy consumption to be competitive, from a natural resource point of view, with the import of soy meal by The Netherlands.

Fossil resources are gradually depleting and becoming more expensive. Therefore, new ways to fuel our economy should be sought. Being a renewable carbon source, biomass will take a key role in the transition to a more sustainable economy. However, while potentially renewable, biomass relies on an intensive cultivation step and it will not be able to deliver a constant and endless supply without inducing other harmful effects. Therefore sustainability assessments of biorefineries are highly relevant. After an introductory first chapter, the sustainability concept and assessment methodologies are studied in chapter two. Based on this information, the life cycle framework is applied in chapter three, in which it is shown that a food and feed company processing wheat can switch to a fossil fuel replacing biorefinery without inducing efficiency losses. On the other hand, the replacement of fossil fuels goes at the cost of other resources such as land, water, minerals, etc. A profound study of the supply chain of different sources of biomass illustrates that the valorization of domestic organic waste and farm residues is an environmentally benign opportunity. These types of biomass however, have lower conversion efficiencies compared to agricultural crops such as silage maize because they often contain more difficult molecules to process such as lignocelluloses requiring more pre- and post-treatment. It is demonstrated that these different types of organic resources can be efficiently converted to a highly energetic biomethane by anaerobic digestion while maintaining nutrients in the digestate, which can be used as fertilizer. Additional emissions causing acidification and eutrophication should however be avoided by good agricultural management. The fourth chapter of this dissertation focuses on methodological development. The quantification of sustainability is a complex task and therefore more research is required to improve assessment techniques. A first identified bottleneck is the acquirement of reliable data. While this is the key to obtain useful results from a life cycle study, it is especially difficult to gather mass and energy balances of future production processes. For this purpose, engineering modules are developed of 22 processes that are commonly used in industry which can be used in prospective sustainability assessments. Although challenges are identified, an application in a case study illustrated the operability and reliability of the approach. The second part of this chapter focuses on the allocation procedure of LCA. It is illustrated that this methodological attribute should be linked to the goal and scope of the assessment. System expansion can give interesting insights in economy wide assessments to assess different product mixes and markets, whereas partitioning is a useful approach in product policies and supply chain improvement. For the latter, exergy is identified as a useful parameter to quantify the physical value of both mass and energy. In a last part of the methodological chapter, an indicator of sustainable development is proposed that focuses on the broader concept of sustainable development. The indicator weighs the antropospheric benefit, quantified as satisfaction by a product or service and the labor quality and quantity, with the ecological burden, quantified as resource and emission impact. These factors are weighted with macro-scale aspects such as the human development index, unemployment rate and the world’s ecological footprint. Overall, it can be concluded that society will have to take better care of its available resources. Biorefineries can have a role in this development by optimally utilizing the available biomass. However, a strong policy is needed that analyzes supply and demand interactions and related impacts such as land use, water use and field emissions. Life cycle assessment will take an essential role in these developments, both in a top-down perspective by analyzing direct and indirect effects of product mixes and markets, as in a bottom-up approach by analyzing and optimizing production chains. On the other hand, more collaborative research is required to better understand different aspects of sustainable development and to search for better ways for a proper assessment of different scopes and scales.

To sustain the needs of growing world population, seas and oceans are becoming heavily exploited. Initially exploited for food and transportation, offshore marine areas are nowadays supplying energy and minerals. Whilst the extraction of terrestrial natural resources led to major environmental consequences (i.e. biodiversity loss), it is crucial to ensure the global environmental sustainability of marine products on their entire life cycle. Life Cycle Assessment (LCA) methods have the potential to provide such information and to identify hotspots of environmental impacts in the value chain of the product under analysis. At the endpoint level, LCA results consider impacts on three areas of protection (AoP): human health, ecosystem quality and natural resources. However, LCA methods have been traditionally applied to industrial processes and thus, are limited to include site-specific aspects (e.g. disturbance of the local ecosystem) in the scope of the assessment. The application of LCA to assess the environmental sustainability of marine products including ecosystem-specific life cycle impact assessments (LCIAs) in the evaluation of impacts belonging to the three AoP. Moreover, quantitative data on mass and energy flows associated to the entire life cycle of the products (production / extraction of raw materials and their processing to final commodities) are required to perform global environmental sustainability assessments. The overall objective of this PhD is to reinforce LCA capacity to assess the global sustainability of marine products. Two operational frameworks are proposed to include site-specific aspects related to the sourcing of marine raw materials, and data related to the processing of wet biomass are provided. In this way, the evaluation of the global environmental sustainability of marine products through LCA will be more inclusive and meaningful for comparative assessments with terrestrial alternatives. The PhD starts with a general introduction (Chapter 1) divided into four sections. First, an overview of marine activities is provided. The most important marine activities in terms of economic importance are described and the concept of the industrial revolution of the seas and oceans is introduced. This refers to the growing importance of the marine-sourced materials and energy for the global economy. Indeed, the importance of the marine economy is expected to follow a two-fold increase by 2030. On a longer time horizon, the potential recovery of deep-sea minerals might significantly increase our dependence on marine commodities. The second section provides background information related to the classification of natural resources and their link with ecosystem services. Natural resources are classified according to renewability, exhaustibility and their form at the moment of extraction (biotic / abiotic). Marine natural resources are presented according to this classification and in the context of ecosystem services. Deep-sea minerals are extensively presented as they might become substantial for our economy in a near future. The ecological pressures on marine ecosystems are discussed in the third section. Direct drivers of impact caused by the marine economy are highlighted, such as the reduction of commercial fish stock size. The fourth section introduces the global concepts of LCA and the development of site-specific LCIA pathways to assess changes in local ecosystem quality, measured through biodiversity related metrics. The main limitations for global environmental sustainability assessments of marine products are exposed. The needs for site-specific marine LCIAs and further data regarding the processing of marine raw materials are highlighted. Chapter 2 quantifies trade-offs amongst seaweed farming and wild catches fisheries. Both are considered as marine natural resources and marine ecosystem services. The reduction in fisheries yields caused by the harvesting of net primary production (NPP) (i.e. seaweed) is estimated through a trophic food web approach. A site-specific LCIA framework relying on the seasonal ecosystem NPP, seaweed biomass growth and fish landings is proposed to assess the Lost Potential Yield (LPY) of the area under study. LPY are reported in terms of biomass, economic value and eco-exergy, a metric measuring the genomic complexity of the organisms. The framework is illustrated for the Greater North Sea and shows a net positive contribution of seaweed farming in terms of marine natural resources (i.e. the production of seaweed exceeds the decrease in fisheries landings for the three LPY metrics). Further research could consist in the development of additional impact pathways to NPP reduction (e.g. habitat provision) and on the consideration of ecosystem carrying capacity. The following chapter (Chapter 3) develops a site-specific LCIA framework to assess impacts of deep seafloor disturbance on regional and global biodiversity as proxy for ecosystem quality. Changes in ecosystem quality are measured through a biodiversity-related metric: the potentially disappeared fraction of species (PDF), expressing relative changes in species richness caused by the intervention. The framework builds on existing LCIAs assessing impacts on ecosystem quality from land-use (i.e. land transformation and occupation). According to existing literature, the framework identifies three kinds of impacts: transformation, occupation and permanent impacts that can be summed to obtain the total impact on regional and global ecosystem quality. The regional biodiversity impacts are first assessed and converted to global biodiversity impacts considering the vulnerability and the scarcity of the ecosystem impacted. The framework is operationalized in a case study consisting to polymetallic nodules mining in the Clarion Clipperton Fracture Zone (CCZ). Despite the very limited knowledge on benthic recovery from deep-sea mining, the framework shows consistency with existing LCA characterization models for biodiversity. The total impact on regional and global biodiversity is mostly influenced by the permanent impact on biodiversity because of the absence of recovery of a significant fraction of species. This framework can be integrated into LCA studies in order to understand the global environmental sustainability of deep-sea activities. Next to the development of additional LCIAs, the availability of detailed and transparent datasets is another challenge to assess the global environmental sustainability of marine products. Chapter 4 computes mass and energy flows associated with the harvesting and the processing of microalgae under eight biorefinery scenarios to produce lipids, proteins, energy and dried biomass. Two cell disruption methods are tested and two solvents for lipid extraction are compared. Complete flowsheets are provided for each step of the downstream processing of the raw biomass. The chapter highlights the impact of the cell disruption method on the total energy demand but also, the influence amongst downstream processes in a cascade design. Lipid extraction has influence on protein extraction, this latter improving energy production as it has a more favourable carbon to nitrogen ratio. In addition, lipids are extracted with a conventional solvent (hexane) for some scenarios and with a biobased solvent (2-methytetrahydrofuran) for other scenarios. The azeotropic distillation required for the recovery of the biobased solvent (and thus its extra energy demand) shows that solvent selection is crucial to control the total energy demand of the process, but lipid profiles will vary according to solvent properties. The last chapter (Chapter 5) consists of the conclusions and perspectives of the manuscript. Whilst the conclusions discuss the main outcomes of the three (published) research chapters (Chapter 2, Chapter 3 and Chapter 4), the perspective section opens a discussion on the requirement for an exhaustive classification of marine ecosystems. In a similar way as for the terrestrial ecosystems, such classification will facilitate the development of databases for marine ecosystem attributes and hence, the implementation of site-specific LCIAs. Furthermore, the section discusses alternatives to species richness related metrics to monitor changes in the ecosystem quality. Different types of biodiversity are defined according to the combination of biodiversity level (i.e. genetic, species, communities and landscape) and biodiversity attribute (i.e. composition, structure, function). Consequently, it is not possible to grasp the entire complexity of biodiversity through a single indicator such as species richness in LCA methods. The use of potential additional indicators for ecosystem quality and the main challenges arising from it are discussed. Finally, the discussion highlights the importance of aligning the scope of LCA studies with the descriptors used by European policy makers to assess the environmental status of marine ecosystems (under the Marine Strategy Framework Directive, MSFD). It emphasizes the needs for additional marine LCIAs to consider all descriptors identified by the MSFD (11) in LCA studies of marine products. The challenge of integrating marine ecosystem services in the scope of LCA studies is considered. Because of the complexity of quantifying ecosystem services and their link with biodiversity, the use of regional biodiversity as midpoint indicator for ecosystem services is proposed. Finally, the section concludes by discussing the challenge of evaluating the total cumulative impact caused by different stressors on a given marine ecosystem. Whilst existing LCIAs do not consider interactions amongst each other, it is relevant to make use of ecological risk assessment tools to model the final ecosystem response to various disturbances occurring in parallel. To conclude, this work has emphasized two main challenges for the global environmental sustainability assessment of marine products: the implementation of site-specific LCIA frameworks and the development of datasets regarding further processing of the harvested products.

A growing demand for resources and competition for land use, especially critical for Europe, is fueling the search for renewable and sustainable products. Innovative, resource-efficient and integrated approaches such as the development of marine biomass fed into integrated biorefineries may bring sustainable and cost-effective solutions to meet the growing needs. Algal biomass is no doubt considered a promising and valuable feedstock for a bio-based economy. Algae are fast-growing aquatic organisms and most of them are autotrophs: they convert sunlight, carbon dioxide, nitrogen and phosphorous (often available in excess) into valuable biomass components, which are of interest for a diverse group of industries, e.g., the food, feed, cosmetics and energy sectors (chapter 1). Despite the large potential of products derived from algae, its cultivation in Europe is still in its early stages and an estimation of the environmental sustainability may guide a further development and scale-up of this sector by highlighting its competitiveness (chapter 2). Chapter 3 illustrates the objectives of this PhD dissertation (addressed in Part I). In Part II, the environmental sustainability (specifically the life cycle resource footprint) of algae production under temperate climate conditions is assessed in an attempt to unravel the bottlenecks of current European production pathways. In chapter 4 and 5, the environmental footprint of microalgae production for higher value applications, and more specific as a feed ingredient, is examined. A first case study concerns an LCA study of microalgae production in Belgium in an innovative cultivation system for aquaculture purposes (chapter 4). Thereafter, the environmental resource footprint of an integrated algal biorefinery located in the Netherlands is assessed (chapter 5). Both case studies consider waste stream mitigation and a comparison was made with the footprint of alternative biomass plants such as soybeans. However, most envFpironmental sustainability assessment methods are rather semi-mature than well-established, which might result in incomplete LCA comparisons. Therefore, Part III of this PhD addresses the need to better quantify the environmental impacts related to surface use, both terrestrial land and sea surface, as this is not straightforward yet in life cycle assessment (LCA). Advanced LCA indicators are proposed in an attempt to better account for the impact of anthropogenic land and sea surface occupation. This development in the field of LCA enables a more fair comparison between the environmental resource footprint of aquatic algae, cultivated on marginal land or in the sea, versus terrestrial crops, of which most of them are grown on fertile land.

Exergy is a thermodynamic metric that represents the amount of useful energy one can obtain out of an object in a given reference environment. The exergy concept is used in several applications: from the analysis of industrial processes to economic, sustainability and ecosystem analysis. In this chapter, the focus is on cumulative exergy consumption (CExC) methods used in sustainability assessment. Since these methods account consistently for the total resource intake, they are often used as measure for environmental impacts, mainly of resource consumption.