In view of the increasing amount of plastic waste due to a yearly rise in production volume, mechanical recycling of post-industrial waste offers a way to use the scarce resources on earth more efficiently in addition to reducing the global warming potential in the production of raw materials. Therefore, this study addresses the calculation of the product carbon footprint for sorted industrial waste according to the specifications of ISO 14067. The plastics acrylonitrile–butadiene–styrene copolymer (ABS), polyamide 6.6 with 30% glass fiber (PA66GF30), polycarbonate (PC) and polyoxymethylene (POM) were balanced in Umberto LCA+ using the Ecoinvent v3.8 and GaBi SP40 2020 databases and primary data collection from the recycling company Occhipinti. A cut-off approach was applied as an allocation method for evaluating the industrial waste so that the plastic for grinding was imported without burdens from the previous product system. The results show that for all plastics under study, one of the main drivers of the carbon footprint is plastic dust from the grinding process. This insight was used in sensitivity analyses to optimize the modelled processes for a more sustainable production. Improvement potentials were identified by using solar power and disposing of the plastic dust separately according to the type of plastic.

Nutrition is responsible for about 30% of global natural resource use. In order to limit the negative impact the nutritional sector has on the environment and on society, the consumption and processing of foodstuffs with assumed low negative impact is an important topic in the effort of sustainable development. In professional kitchens, clearly defined indicators assessing the impact of business activities are needed in this effort. The research and development in the NAHGAST project provides groundwork that could be of important assistance in this effort. Two versions of an assessment tool, with indicators of different complexity (NAHGAST Meal-Basic and NAHGAST Meal-Pro), were developed that can be used by kitchen professionals to determine the sustainability performance of their products—the offered meal. An informed selection of indicators, and a discussion of what processes and impacts this indicator relates to in the wider context, are essential and are discussed in this paper. Furthermore, in the selection of indicators for the purpose of our research certain criteria were considered simultaneously: (1) Communicability—What information an indicator can communicate and how comprehensible this information is for different actors; (2) Feasibility and data availability—Whether there is sufficient data for an indicator to be included and whether it is realistic for companies to integrate this indicator in their daily work practice; and (3) Scientific relevance—Whether the indicator is relevant for sustainability efforts on a larger scale and for related discussions in the scientific community. Insights related to these considerations are valuable for future developments in sustainability assessment in out-of-home gastronomy. The tool has been used to evaluate a number of dishes and results are deemed meaningful. However, assessments must not be understood as an accurate measurement but as an approximation of the sustainability of meals. At the level of individual indicators, they allow a detailed analysis and targeted optimization of recipes, while the aggregated results in the form of labels can be communicated well to customers. However, deficiencies and challenges, as discovered in the application phase of the project, demonstrate research gaps in the wider context. Finally, further steps for an integration of the tool in company processes and remaining options for companies to adjust the tool are discussed.

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Since the beginning of 2023, the so-called reusable packaging obligation has been in place in Germany in order to reduce the amount of waste from takeaway packaging. Catering companies will then be obliged to offer reusable packaging as an alternative to disposable plastic takeaway packaging. As part of the pilot project ‘Mehrweg Modell Stadt’ (‘Reusable city model’), an open infrastructure for reusable cups is in trial in Mainz and Wiesbaden. The project was subjected to a scientific monitoring process, which included the implementation of quantitative surveys among various stakeholders within the value chain, namely consumers, catering companies, and other companies engaged in the project. This was conducted over two time periods: August 2023 to September 2023, and February to March 2024. The results show a discrepancy between consumers’ attitudes and their actual behavior: Despite a high level of sustainability awareness and perceived positive benefits of reusable packaging, perceived barriers stand in the way of actual use. The biggest challenges for companies are the lack of consumer demand, practical handling and hygiene requirements. The results of this quantitative social research provide important insights for the development of targeted measures to promote the use of reusable packaging in takeaway catering and contribute to the discussion on closing the attitude–behavior gap along the entire value chain.

Sustainability as a guiding idea for societal and economic development causes a growing need for reliable sustainability assessments (SAs). In response, a plethora of increasingly sophisticated, standardizAed, and specialized approaches have emerged. However, little attention has been paid to how applications of SAs in different contexts navigate the challenges of selecting and customizing SA approaches for their research purposes. This paper provides an exploration of the context-specific conditions of SA through a case study of three research projects. Each case study explores the different approaches, methodologies, as well as difficulties and similarities that researchers face in “doing” SA based on the research question “What are common challenges that researchers are facing in using SA approaches?” Our case study comparison follows a most different approach for covering a wide range of SA applications and is structured along with three key challenges of doing SA: (i) Deliberation, learning and assessment; (ii) normative assessment principles; (iii) feasibility, especially regarding data quality/availability. Above all, the comparative case study underlines the role and importance of reflexivity and context: We argue that a more explicit and transparent discussion of these challenges could contribute to greater awareness, and thus, to improving the ability of researchers to transparently modify and customize generic SA methodologies to their research contexts. Our findings can help researchers to more critically appraise the differences between SA approaches, as well as their normative assumptions, and guide them to assemble their SA methodology in a reflexive and case-sensitive way.

Considering the challenges of decarbonization, the energy transition, and the necessity to increase resource efficiency in the context of the circular economy, there is a need to develop sustainable solutions for the material and energy use of biogenic waste. Biogenic waste, which remains underutilized and can be regarded as an untapped resource, offers significant potential for sustainable energy production. In this context, biogas plants are a key technology, as they convert biogenic waste into renewable energy, reduce greenhouse gas emissions, and contribute to closing material cycles. The standardized life cycle assessment (LCA) methodology is a tool for the systematic analysis and evaluation of environmental impacts of products, systems, or services. The objective of this study is to develop a methodological and conceptual framework for the LCA of the innovative biogas plant based on a rotating drum fermenter. The environmental aspects of biowaste utilization and the role of the biogas plant in waste reduction and energy production are discussed in the broader context of the circular economy. Due to its complexity, this paper considers LCA with focus on the definition of the goal and scope of the study in accordance with international standards.