Kathrin Greiff

• Univ.-Prof. Dr.
• Full Professor and Managing Director at RWTH Aachen University

Storing and streaming hyperspectral images (HSI) requires significant resources. One suitable strategy of reducing this resource utilizations is the use of compression algorithms. In this work, we benchmarked Bzip2, Gzip, LZ4 and lzf algorithms on a dataset of HSIs of lightweight plastic packaging and achieved a lossless compression as high as 96.7...

In recent years, the development of real-time applications has become increasingly popular in the field of sensorbased systems and recyclable waste streams. One promising method is sensor-based real-time characterization (SBRTC) involving object detection or instance segmentation models as well as specific datasets containing recyclable materials t...

The circular economy (CE) is a key pillar of sustainability policies, notably the European Green Deal, requiring extensive data across the value chain. However, the lack of a clear definition of CE data creates ambiguity in its understanding and application. This study addresses this gap by investigating the fundamental research questions: What are...

Paper recycling offers environmental and economic advantages compared to primary paper production. However, a relevant quantity of the produced paper and board in Germany is currently discarded in mixed waste collections such as lightweight packaging, residual and commercial waste. These papers and boards are often not material recycled. Therefore,...

As we are still not on track to achieve environmental sustainability through technological change, we need to further stress the importance of understanding routinized types of behaviour by private households and the environmental assessment of corresponding consumption of resources. Social practice theories allow us to understand the constitution...

The recycling of paper and board (PB) yields economic and environmental advantages compared to primary paper production. However, PB from lightweight packaging (LWP) waste is currently not comprehensively reintegrated into the paper value stream. To develop an adapted recycling process for PB from LWP, PB quantities, qualities, and fluctuations ran...

In the context of the Circular Economy (CE), quality is one of the most widely used keywords, but generally perceived as an ambiguous term without further definition or explanation. The present paper analyzes the use of the term product quality in the context of the CE through a systematic literature review including 132 peer-reviewed journal artic...

Sustainability transformation is a multi-dimensional and comprehensive approach covering various aspects, environmental, economic, and social, and transformation itself. To give direction to sustainability action, sustainable development goals (SDGs) play an essential role. Even though SDGs are comprehensive and give orientation for sustainability...

Vor dem Hintergrund einer weiter anwachsenden Bedeutung der Circular Economy für den Klimaschutz und auf Grundlage des KrWG 2020, Green Deal und der EU-Kreislaufstrategie: Das neue Handbuch verschafft Ihnen einen umfassenden, interdisziplinären Überblick zum hochaktuellen Thema Kreislaufwirtschaft. Die akuten Problemfelder, mit denen sich Praktiker...

Even though carbon fibres (CFs) have been increasingly used, their end-of-life (EOL) handling presents a challenge. To address this issue, we evaluated the use of recycled CFs (rCFs), produced through pyrolysis, as rovings to be used in textile reinforced concrete structures. Mechanical processing (hammer mill) with varying machine settings was the...

Overlapping material flow presentations in construction and demolition waste (CDW) recycling make an inline particle size distribution (PSD) monitoring challenging. Here, we aim to build a deep-learning-based segmen-tation model for overlapping particles in 3D-laser-triangulation images of CDW. Our model was trained on three specially designed data...

Ballistikseparatoren werden innerhalb der Aufbereitung von Leichtverpackungsabfällen eingesetzt, um Papier und Folien von 3D-Kunststoffen zu trennen. Dabei können verschiedene Parameter Einfluss auf die Trennung von 2D- und 3D-Komponenten besitzen. In den vorgestellten Versuchen wurden drei verschiedene Winkel der Trennfläche, fünf Umdrehungsgeschw...

Today’s post-consumer plastic recycling is limited by labor-intensive manual quality control (MQC) procedures, resulting in largely unknown pre-concentrate purities. Sensor-based quality control (SBQC) could enable an automated inline quality monitoring and thus contribute to a more transparent and enhanced plastic recycling. Therefore, we investig...

In the past decades, the German paper industry has been increasing the sustainability of paper production by continuously using more recovered paper. Today, recovered paper is an essential secondary raw material to produce new paper. Nevertheless, around 20 % of the paper produced in Germany is still not returned to the recovered paper stream and i...

The sustainable transformation of society is one of the greatest challenges of our time. Universities are central actors for knowledge generation and transfer in the sustainability field and, at the same time, are facing the question of how they can become sustainable social actors and make their activities and infrastructure sustainable. Against t...

The global environmental crisis, technological developments, the COVID-19 pandemic, and ongoing economic and political globalization are just a few of the developments that are massively increasing the pressure for transformation on regions, companies, and society as a whole. In addition, the digital age is accelerating transformation processes tha...

Sorting plants are crucial for effective recycling, but their optimization can be challenging due to the hetero-geneity of waste streams. We introduce a novel approach to holistically optimize sorting plants using digital twins containing data-driven process models. To demonstrate their technical feasibility, we developed a data-driven process mode...

Sensor-based sorting (SBS) has been widely applied in the recycling industry for various waste types for more than two decades. Compared to manual sorting, SBS achieves higher throughputs, reproducible sorting results, and higher automation degrees. While the sortable particle features of traditional sorting methods (e.g., wind sifting or magnetic...

Determining mass-based material flow compositions (MFCOs) is crucial for assessing and optimizing the recycling of post-consumer plastics. Currently, MFCOs in plastic recycling are primarily determined through manual sorting analysis, but the use of inline near-infrared (NIR) sensors holds potential to automate the characterization process, paving...

Purpose Life cycle assessment (LCA) is increasingly being applied to construction and demolition waste (CDW) recycling. But what is the current state of LCA studies on CDW recycling? In the context of circular economy, several aspects become important in LCA, such as avoided impacts and consideration of the quality of recycled materials. The aim of...

Current lightweight packaging (LWP) sorting plants are underperforming, and one of the most important reasons is the fluctuation in LWP input materials. Drum sieving is an essential process in LWP waste processing and recycling, as it is one of the first preconditioning steps and could influence all subsequent processes. If the parameter settings o...

The air‐hardening ductile forging steels belong to the third generation of advanced high strength steels and achieve their final, martensitic microstructure simply by air‐cooling from the forging heat. The present conference paper reviews the 15 years of development, different alloying strategies and metallurgical throwbacks like manganese embrittl...

Mass-based material flow compositions (MFCOs) are crucial to assess and optimize mechanical plastic recycling processes. While MFCOs are determined by manual sorting analysis today, in the future MFCOs could be determined inline through near-infrared-based material flow characterization. This study aims to quantify the accuracy of near-infrared-bas...

Shrink sleeves interfere with the mechanical recycling of plastic bottles because of their poor sortability during near-infrared (NIR)-based sorting. This study aims to identify reasons for their poor sortability and to propose solutions to overcome them. Five machine learning (ML) algorithms (decision tree, random forest, support vector machine, p...

Vorwort Nur noch sieben Jahre bis 2030, dem Jahr, in dem wichtige Meilensteine der EU- und der deutschen Klimapolitik sowie vieler Industrieunternehmen auf dem Weg zu einer „net-zero“- Betriebsweise erreicht sein sollen! In dieser Zeit müssen die Konzepte entwickelt und zumindest großtechnisch erprobt werden, die uns dann im Zeitfenster 2045-2050 w...

Expanded Polystyrene (EPS) used in External Thermal Insulation Composite Systems (ETICS) is mainly disposed of in waste incineration plants. However, alternative recycling options need to be identified as capacities for this waste treatment are limited and the amount of EPS-based ETICS waste is expected to increase. Herein, it is necessary to quant...

Das werkstoffliche Recycling von Post-Consumer Kunststoffverpackungen weist trotz bisheriger Bemühungen deutliche Optimierungspotentiale auf. Bereits während der ersten Behandlungsstufe in Sortieranlagen treten erhebliche Wertstoffverluste auf; gleichzeitig werden mangelnde Sortierqualitäten vielfach kritisiert. Ein möglicher Grund dieser Defizite...

Mass-based material flow compositions (MFCOs) are crucial to assess and optimize mechanical plastic recycling processes. While MFCOs are determined by manual sorting analysis today, in the future MFCOs could be determined inline through near-infrared-based material flow characterization. This study aims to quantify the accuracy of near-infrared-bas...

The steel industry is responsible for a quarter of all industrial greenhouse gas emissions. So far, the environmental savings are mainly due to steel recycling. Besides recycling, the circular economy offers strategies to increase material efficiency and thus decrease the primary raw material demand. However, the potentials remain unexploited becau...

In material development processes, the question if a new alloy is more sustainable than the existing one becomes increasingly significant. Existing studies on metals and alloys show that their composition can make a difference regarding the environmental impact. In this case study, a recently developed air hardening forging steel is used to produce...

The material recycling of complex waste streams such as external thermal insulation composite systems (ETICS) is challenging, which is why their recycling in the sense of a circular economy is currently hardly established. Therefore, the combined mechanical and thermochemical recycling of ETICS based on expanded polystyrene (EPS) is investigated ex...

Digital technologies hold enormous potential for improving the performance of future-generation sorting and processing plants; however, this potential remains largely untapped. Improved sensor-based material flow characterization (SBMC) methods could enable new sensor applications such as adaptive plant control, improved sensor-based sorting (SBS),...

Sensor-based sorting is an essential technology in processing primary and secondary raw material. Over the past 30 years, sensor technology has provided important development impulses for increasing the efficiencies of processing procedures and processing chains regarding throughput, yield, and product quality. However, increasing material composit...

Background: Sensor-based sorting (SBS) units are a crucial part of lightweight packaging (LWP) waste sorting plants. Compared to sorting trials under technical lab conditions, significantly lower sorting performances are observed in many LWP sorting plants. One reason for this discrepancy is assumed to be the insufficient material flow representati...

Ein ausschlaggebendes Qualitätskriterium für Recyclingbaustoffe ist die Korngrößenverteilung (KGV) nach DIN 66165-1, die mittels manueller Siebanalysen bestimmt wird. Siebanalysen sind zeit- und kostenaufwändig und Analyseergebnisse nur mit Zeitverzug verfügbar. Eine sensorbasierte Ermittlung von KGVs würde diese Probleme lösen und neue Anwendungen...

Sensorbasierte Sortierverfahren haben in den letzten fast vier Dekaden breite Resonanz in Behandlungsanlagen der Recyclingindustrie gefunden. Während zu Beginn des Einsatzes dieser Technologie vor allem der Vorteil hoher Kapazitäten genutzt wurde, erlauben technologische Entwicklungen inzwischen auch die Erfüllung sehr anspruchsvoller Sortieranford...

The large-amount production and application of plastics since the 1950s has led to different environmental problems, and the production amount is still increasing. In 2015, 79 wt% of all plastic waste was accumulated in landfills or the natural environment. Due to their negative influence to the environment, the problems of landfilling and marine l...

Sensor-based material flow characterization (SBMC) promises to improve the performance of future-generation sorting plants by enabling new applications like automatic quality monitoring or process control. Prerequisite for this is the derivation of mass-based material flow characteristics from pixel-based sensor data, which requires known individua...

Presentation about the Circular Economy Strategy of the RWTH Aachen University at the ASK 2021 Conference

Our modern industrial society is inconceivable without metals. Metals can be found in a large number of our products, in our buildings and infrastructures. Each metal has different, but unique properties that our society is able to use skillfully. The sustainable use of metals is a prerequisite for a sustainable industrial society. Corresponding st...

This poster introduces the project Circle of Tools, which implements the CE concepts re-manufacturing and re-engineering in three companies, i.e. tool manufacturers, in Germany. This pilot project aims for a reduction in energy and resource demand. As part of a Phd project, a general methodology to measure the environmental impact of CE concepts sh...

The paper describes patterns of resource use related to German households’ equipment. Using cluster analysis and material flow accounting, data on socio-demographic characteristics, and expenditures on fuel, electricity and household equipment allow for a differentiation of seven different household types. The corresponding resource use, expressed...

This chapter addresses the resource consumption and GHG emissions associated with household activities and household types. Over the course of 6 weeks 16 participating households were asked to provide data regarding their activities in the fields of housing, mobility, nutrition, waste, goods and appliances, tourism and recreation. This extensive su...

This chapter introduces empirical social research on social milieus, and why lifestyles are of interest to Living Lab research. We present the results of a milieu analysis for Living Lab research in Bottrop. We enrich the findings from the milieu analysis by describing the influence of lifestyles on heating practices, combining a representative sta...

The concept Material Input per Service Unit (MIPS) was developed 20 years ago as a measure for the overall natural resource use of products and services. The material intensity analysis is used to calculate the material footprint of any economic activities in production and consumption. Environmental assessment has developed extensive databases for...

Against the background of prognosticated rising levels of global resource consumption it is an indispensable challenge in the 21st century to achieve sustainable development, meaning that society's welfare generation has to happen within the natural system's boundaries. To do so, transition processes need to be designed to leave this currently unsu...

Hintergrund Der Klimaschutz ist in den letzen Jahren immer stärker zu einem zentralen Thema der Umweltpolitik geworden. Aktuelle politische Zielsetzungen fordern deswegen einen Anteil von erneuerbaren Energien am Primärenergieverbrauch von 20 % bis 2020. Energie aus Biomasse hat derzeit den größten Anteil bei den erneuerbaren Energien, die zur Redu...

The German Federal Government's ambitious plans for increasing the proportion of renewable energy in energy generation by 2020 can only be achieved by large-scale use of biomass for power generation and other measures. The motto is therefore: from food farming to energy farming. The food industry views this trend with apprehension. This paper descr...

The ambitious aims of the German government to increase the portion of the renewable energies on the energy generation until 2020 can amongst other only be achieved with massive use of biomass for the energy generation. Therefore, the slogan is "From farmer to energy farmer". The food industry is concerned about these developments. The achieved sta...

Die ehrgeizigen Ziele der Bundesregierung zur Steigerung des Anteils der erneuerbaren Energien an der Energieerzeugung bis 2020 können u.a. nur durch einen massiven Einsatz von Biomasse zur Energieerzeugung erreicht werden. Vom Landwirt zum Energiewirt lautet deshalb die Parole. Die Lebensmittelindustrie sieht diese Tendenzen mit Besorgnis. Der err...

Nogo-A is a physiologically relevant inhibitor of neuronal growth and regeneration in the myelin of the adult human central nervous system and has attracted considerable attention as a molecular target for the treatment of spinal cord injuries. To gain insight into the structural and functional properties of the large extramembrane region that is c...

Die Möglichkeiten zur Bereitstellung von Energie aus Biomasse sind vielfältig. Als prinzipielle Wege existieren physikalisch-chemische Verfahren, wie Pressung und Extraktion, biochemi-sche Umwandlungsverfahren, z.B. zu Ethanol oder Biogas, und die thermochemischen Verfahren Pyrolyse, Vergasung und Verbrennung. Abbildung 1 zeigt vereinfacht die mögl...