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In recent decades, there has been growing interest in the thermal conversion of various alternative fuels, such as biomass and waste-derived fuels. One of the technological solutions for the so-called direct co-combustion of fuels is to create mixtures of various fuels, called mixed secondary fuel. However, mixed secondary fuel has different properties compared to primary fuels. Due to this, by properly selecting the types and proportions of mixtures, it is possible to eliminate their potentially negative impact on both combustion technology and the natural environment. In this paper, we decided to prepare mixed secondary fuel by mixing sunflower husk pellets with RDF (refuse-derived fuel) in a ratio of 1:1 and then analyze the combustion process of the produced fuel in fluidized bed conditions. The results obtained on the basis of the presented research indicate that the mixed secondary fuel eliminated the impact of alkali metal compounds on reducing the melting point of ash and, consequently, on the combustion process of the mixed secondary fuel. An additional benefit is the reduction of emissions of harmful compounds into the atmosphere occurring during the combustion of municipal waste and compliance with the concept of the circular economy. [ABSTRACT FROM AUTHOR]

The momentum of the Fourth Industrial Revolution is driving increased demand for certain specific metals. These include copper, silver, gold, and platinum group metals (PGMs), which have important applications in renewable energies, green hydrogen, and electronic products. However, the continuous extraction of these metals is leading to a rapid decline in their ore grades and, consequently, increasing the environmental impact of extraction. Hence, obtaining metals from secondary sources, such as waste electrical and electronic equipment (WEEE), has become imperative for both environmental sustainability and ensuring their availability. To evaluate the sustainability of the process, this paper proposes using an exergy approach, which enables appropriate allocation among co-products, as well as the assessment of exergy losses and the use of non-renewable resources. As a case study, this paper analyzes the recycling process of waste printed circuit boards (PCBs) by disaggregating the exergy cost into renewable and non-renewable sources, employing different exergy-based cost allocation methods for the mentioned metals. It further considers the complete life cycle of metals using the Circular Thermoeconomics methodology. The results show that, when considering the entire life cycle, between 47% and 53% of the non-renewable exergy is destroyed during recycling. Therefore, delaying recycling as much as possible would be the most desirable option for minimizing the use of non-renewable resources. [ABSTRACT FROM AUTHOR]

Municipal sewage sludge (MSS) is an inevitable byproduct of wastewater treatment, with increasing amounts year by year worldwide. The development of environmentally and economically acceptable methods for the sustainable management of MSS is a major environmental challenge. Nowadays, sludge management practices, besides the commonly used stabilization methods, focus attention on alternative sludge-disposal pathways, which encompass enhanced energy and valuable-resource recovery. This review presents the recent advances in the recovery of selected value-added products from sludge. Because of the high nitrogen and phosphorus concentrations, waste MSS can be a nutrient source (e.g., struvite). This paper discusses the conditions of and advances in the technology of struvite recovery. As in the extracellular polymeric substances (EPSs) of biological sludge, alginate-like exopolymers (ALEs) are present in MSS systems that treat municipal wastewater. The yields, dynamics in content, and characterization of ALEs and their possible applications were analyzed. MSS is an important source of humic substances. Their occurrence, characterization, and yields in various types of MSS (e.g., untreated, composted, and digested sludge) and main methods of application are presented. The important aspects and trends of MSS pyrolysis, including the thermochemical conversion to biochar, are discussed in this review. The characterization of biochar derived from MSS and the assessment of the environmental risks are also covered. This paper explores the potential use of biochar derived from MSS in various applications, including soil amendment, carbon sequestration, and environmental remediation. [ABSTRACT FROM AUTHOR]

In times of climate change and dwindling fossil resources, the need for sustainable renewable energy technologies gains importance, increasingly fast. However, the state of the art technologies are energy intensive in their production, like monocrystalline photovoltaic, or even consist of not recyclable composite material, in the case of wind turbine blades. Despite a lack in efficiency and stability, dye sensitized solar cells (DSSC) have a high potential to supplement the state of the art green energy technology in future. With low production costs and no necessity for toxic compounds DSSCs are a potential product, which could circulate in the loops of a circular economy. Therefore, with this paper, we provide the status of research on DSSC recycling and an outlook on how recycling streams could be realized in the future for glass-based DSSCs without toxic components. The overview includes work on using recycled material to build DSSCs and extending the life of a DSSC, e.g., through rehydration. We also illustrate the state of sustainability research for DSSCs using the VOSviewer tool. To date, the term sustainability appears in 35 of 24,441 publications on DSSCs. In view of the global challenges, sustainability should be researched more seriously because it is as important as the efficiency and stability of DSSCs. [ABSTRACT FROM AUTHOR]

The transition towards renewable energy is not as impressive as expected when considering the wide array of efforts undertaken. Energy-abundant countries do not have sufficient stimuli to curb the use of fossil fuels; some of them even work on increasing international supply. Greenhouse gas emissions remain high. As the world population grows, more attention must be devoted to the transition towards renewables. This transition requires additional resources and leaves behind waste that must be recycled. Without a circular economy, the transition towards renewable energy will require extra power, resulting in a spiral that is very detrimental to the environment of our planet. This paper provides a picture of the current situation, discusses tendencies, and systemizes issues that must be tackled. [ABSTRACT FROM AUTHOR]

A significant number of first-generation offshore wind turbines (OWTs) have either reached or are approaching the end of their operational lifespan and need to be upgraded or replaced with more modern units. In response to this concern, governments, regulatory bodies and industries have initiated the development of effective end-of-life (EOL) management strategies for offshore wind infrastructure. Lifetime extension is a relatively new concept that has recently gained significant attention within the offshore wind energy community. Extending the service lifetime of OWTs can yield many benefits, such as reduced capital cost, increased return on investment (ROI), improved overall energy output, and reduced toxic gas emissions. Nevertheless, it is important to identify and prepare for the challenges that may limit the full exploitation of the potential for OWT lifetime extension projects. The objective of this paper is to present a detailed PESTLE analysis to evaluate the various political, economic, sociological, technological, legal, and environmental challenges that must be overcome to successfully implement lifetime extension projects in the offshore wind energy sector. We propose a decision framework for extending the lifetime of OWTs, involving the degradation mechanisms and failure modes of components, remaining useful life estimation processes, safety and structural integrity assessments, economic and environmental evaluations, and the selection of lifetime extension technologies among remanufacturing, retrofitting, and reconditioning. Finally, we outline some of the opportunities that lifetime extension can offer for the wind energy industry to foster a more circular and sustainable economy in the future. [ABSTRACT FROM AUTHOR]

In recent years, there has been considerable focus on ensuring that energy is used in the most efficient manner possible. This is due to the fact that globally, over 70% of energy is generated from fossil fuels. Consequently, the matter of designing and utilizing materials that will negate energy losses within the construction industry is of paramount importance. Simultaneously, the necessity for a sustainable approach to the design and production of materials is strongly emphasized. This paper presents an innovative approach to the use of a combination of mineral and plant-based fillers in polyurethane foam technology as a thermal insulation material with the potential to be used in construction to reduce energy consumption. Polyurethane composites containing fly ash from biomass combustion and the addition of rice, sunflower, and buckwheat husks as plant fillers were proposed. The structure of the obtained materials was studied, and the most important physical properties were analyzed. These included apparent density, dimensional stability, water absorption, and the effects of UV radiation and water influence on the carbon, hydrogen, nitrogen, and oxygen content. Moreover, the mechanical properties of the materials were investigated, including compressive strength and brittleness. Additionally, the foams were subjected to flammability tests using a cone calorimeter. Furthermore, additional parameters were determined, including the limiting oxygen index and the vertical and horizontal flammability tests. The results demonstrate the beneficial effects of combining mineral and vegetable fillers in polyurethane foam. [ABSTRACT FROM AUTHOR]

This text mining study delves into the multifaceted contributions of the energy sector to Sustainable Development Goals (SDGs). By analyzing 363 papers, we uncover key themes, trends, and challenges shaping the intersection of energy and sustainability. The findings reveal that the energy sector plays a pivotal role in achieving SDGs such as affordable and clean energy (SDG 7) and climate action (SDG 13). Critical issues encompass governance, policy frameworks, and technological innovations. This research underscores the need for interdisciplinary collaboration and holistic approaches in addressing complex energy-related sustainability challenges. The insights derived here provide guidance to policymakers, researchers, and stakeholders seeking to harness the energy sector's potential for a more sustainable and equitable future. [ABSTRACT FROM AUTHOR]

Ever since the introduction of lithium-ion batteries (LIBs) in the 1970s, their demand has increased exponentially with their applications in electric vehicles, smartphones, and energy storage systems. To cope with the increase in demand and the ensuing environmental effects of excessive mining activities and waste production, it becomes crucial to explore ways of manufacturing LIBs from the resources that have already been extracted from nature. It is possible by promoting the re-usage, refurbishing, and recycling of the batteries and their constituent components, rethinking the fundamental design of devices using these batteries, and introducing the circular economy model in the battery industry. This paper through a literature review provides the current state of CE adoption in the lithium-ion battery industry. The review suggests that the focus is mostly on recycling at this moment in the battery industry, and a further understanding of the process is needed to better adapt to other CE practices such as reuse, remanufacture, refurbishment, etc. The paper also provides the steps involved in the recycling process and, through secondary case studies, shows how some of the industries are currently approaching battery recycling. Thus, this paper, through review and secondary cases, helps us to understand the current state of LIB recycling and CE adoption. [ABSTRACT FROM AUTHOR]

Reducing the phenomenon of food waste and effective management of already wasted food in the form of post-consumer waste, included in the source-separated organic fraction of municipal solid waste (SS-OFMSW) from households and catering facilities, are some of the key challenges of the circular economy (CE), in particular in highly urbanized areas. The basis for the effective use of this waste is the knowledge of its physical and chemical properties. The main objective of the paper is to identify the key technological and organizational parameters for selective collection determining the characteristics of the SS-OFMSW and, consequently, the optimal path for its management. This paper presents the results of qualitative research of SS-OFMSW generated in the capital of Poland—Warsaw—coming from three sources: multi- and single-family housing and catering facilities. The collection efficiency of this waste was determined in the form of quality in container rate (QCR = 92–97%) and variability in terms of impurities and admixtures present in it (CV = 56–87%). High variability indicates that the system of selective waste collection in Warsaw is immature, which may hinder undertaking activities in the field of waste management planning. The study confirmed the suitability of the tested SS-OFMSW for organic recycling, especially using anaerobic digestion (AD), to which it is predisposed by water content, C/N, and biomethane potential (BMP). All tested food waste is characterized by a high yield of biogas in the range of 384–426 m3/Mg VS and an average share of methane in biogas at the level of 52–61%. Fertilizer properties, moisture, and its gas potential show little variability (CV ≤ 16%), which means that these data can be treated as stable data. The obtained results indicate the optimal direction for the collection and processing of SS-OFMSW based on post-consumer food waste in urbanized areas. [ABSTRACT FROM AUTHOR]

Pyrolysis is a promising technology for transforming waste plastics (WPs) into high-value products. In the near future it will play a key role in the circular economy, as a sustainable and environmentally friendly method of managing this waste. Although the literature reports on the pyrolysis of plastics, it is focused on pure polymers. On the other hand, the state-of-the-art knowledge about the pyrolysis of mixed and contaminated WPs is still scarce. Industrial waste processing usually uses polymer mixtures containing various impurities that influence the pyrolysis process during chemical WPs recycling. In the paper the pyrolysis of three types of WPs: low density polyethylene (LDPE), polyvinyl chloride (PVC) and polyvinyl butyral (PVB) from repeated mechanical recycling of plastics, as well as their binary and ternary mixtures, is considered. The influence of particular components on the pyrolysis process is analyzed. The aim is to determine synergistic behavior of the mixtures during the pyrolysis process, which is important for increasing the efficiency and quality of the obtained bioproducts. Methods such as thermogravimetric (TG/DTG) analysis coupled with Fourier transform infrared spectroscopy (FTIR) and mass spectroscopy (MS) are used. The variations in the initial and final temperature of pyrolysis, mass loss and mass loss rate are determined. The content of PVC significantly lowers the initial temperature and mass loss and increases the final temperature. The pyrolysis of the considered mixtures shows a noticeable synergism—in the initial stage of pyrolysis up to a temperature around 450 °C, the mass loss is accelerated compared to what is predicted by simple superposition. The inhomogeneity of the mixtures as well as the waste origin causes a significant variation in the activation energy. Three main conclusions are obtained: (i) if the waste does not contain PVC, the pyrolysis is nearly complete at a temperature around 500 °C at a heating rate of 10 °C/min, whereas PVC is not fully processed even at 995 °C; (ii) the synergistic effects affect significantly the pyrolysis process by accelerating some steps and lowering the activation energy; and (iii) the presence of PVC noticeably lowers the temperature of the first stage of PVB pyrolysis. The investigation results prove that chemical recycling of mixed LDPE, PVC and PVB waste can be an effective method of plastic waste management. [ABSTRACT FROM AUTHOR]

Waste glycerol can be subjected to various processing operations, including purification and refining, to obtain glycerol of an appropriate purity. Alternative methods for utilising waste glycerol are also being sought, e.g., by converting it into other valuable chemical products or biofuels. Therefore, various technologies are being developed to ensure effective and sustainable utilisation of this type of waste. The production of value-added products from waste glycerol strongly determines the improvement of the economic viability of biofuel production and corresponds to the model of a waste-free and emission-free circular economy. This paper characterises the mechanisms and evaluates the efficiency of existing methods for microbiological utilisation of waste glycerol into liquid biofuels, including biodiesel, bioethanol and biobutanol, and identifies further production avenues of value-added products. In addition, it presents the results of a bibliographical analysis of publications related to the production of liquid fuels and economically valuable products from glycerol, assesses the progress of research and application work and, finally, identifies areas for future research. [ABSTRACT FROM AUTHOR]

Sustainable development involves constant efforts to reduce pollution by using resources as efficiently as possible. One of the sources of pollution is waste from packaging, recovery, and of course, the possibility of recycling them. The research theme of this paper is the reverse logistics of plastic packaging, which allows the realization of the idea of circular economy and green logistics, which promotes the idea of sustainable development. The EU is strongly committed to issues related to the management of plastic packaging and waste to reduce environmental pollution and achieve circularity goals. Through this article, we aim to highlight the degree to which the EU member states are included in the plastic packaging recycling targets for the year 2030. To highlight the evolution trend for the recycling rate of plastic packaging, we used an advanced forecasting model that runs a series of variables in order to draw up a forecast as accurate as possible. After highlighting the recycling rates for plastic packaging at the level of the EU member states, we proceeded to outline some recommendations in order to encourage the EU member states to make the recycling process more efficient. The current study continues the series of studies dealing with the problem of recycling, but it covers a topic not addressed until this moment, namely the behavior of the citizen regarding the recycling activity seen through the prism of national culture. The current study aims to strengthen the specialized literature in this field and to offer innovative solutions that appeal to the respective national cultures regarding the availability of the populations of the EU member states to address the problem of recycling plastic packaging, not only from a legislative perspective but also from a cultural one. In conclusion, this study generates a model of approach to government policies regarding the recycling of plastic packaging considering the types of national cultures prevailing in the EU member countries, with this being possible by grouping the countries into culturally homogenous clusters. In this way, the environmental policies enunciated by governments can be adapted to convey the message in a more personal way, considering the cultural differences between the EU member states. [ABSTRACT FROM AUTHOR]

The novelty of the paper is the analysis of the possibilities of reducing the operating costs of a mine water pumping station in an abandoned coal mine. To meet the energy needs of the pumping station and reduce the carbon footprint, "green" energy from a photovoltaic farm was used. Surplus green energy generated during peak production is stored in the form of green hydrogen from the water electrolysis process. Rainwater and process water are still underutilized sources for increasing water resources and reducing water stress in the European Union. The article presents the possibilities of using these waters, after purification, in the production of green hydrogen by electrolysis. The article also presents three variants that ensure the energy self-sufficiency of the proposed concepts of operation of the pumping station. [ABSTRACT FROM AUTHOR]

The synthesis and utilization of zeolites derived from fly ash (FA) gained significant attention years ago due to their potential to address environmental challenges and promote sustainable practices subscribing to the circular economy concept. This paper highlights the recent findings regarding the synthesis and utilization of zeolites derived from FA. It begins with a discussion about the recent challenges regarding industrial waste management and statistics regarding its availability on the global market with a special insight into the situation in Poland. The characteristics of FA obtained from various fuels were presented and the main differences were highlighted. Then, different methods used for the synthesis of zeolites from FA were discussed in small and pilot scales taking into consideration the main challenges and problems. The analytical methods used in porous materials synthesis verification and properties determination were described. The sorption properties of FA-derived zeolites were presented and discussed. Finally, the paper emphasizes the potential applications of fly ash-derived zeolites in different fields. Their importance as sustainable alternatives to conventional materials in industry, construction, agriculture, power, medicine, and other industrial sectors was analyzed. [ABSTRACT FROM AUTHOR]

This paper explores the implementation of the circular economy in the energy sector. The research findings contribute to our understanding of the practical application of the circular economy, enabling policymakers and stakeholders to make informed decisions and develop targeted strategies. The study analyzes 88 Portuguese companies' reports, examining the presence of circular economy strategies and initiatives. The results reveal that energy sector companies tend to prioritize reporting their greenhouse gas reduction efforts over their circular economy strategies. The findings align with previous studies in the oil and gas industry, emphasizing the significance of sustainability reporting and potential biases in reporting practices. The study also identifies a gap between circular economy terminology and its representation in reports, indicating the need for greater incorporation of circular economy-oriented initiatives in the energy sector. The research highlights the role of technology in fostering innovation and calls for strategic alliances and knowledge sharing to drive circular economy practices. Further research is recommended to understand the barriers to implementing circular economy practices and identify effective solutions. Overall, this paper provides valuable insights for advancing the circular economy in the energy sector and achieving broader sustainability goals. [ABSTRACT FROM AUTHOR]

The circular economy model is based on the 4R framework—reduce, reuse, recycle, and recover. While recycling was the primary focus in the past, the shortage of raw materials and the desire to reduce carbon footprints have led to a change in focus: end-of-life materials are now considered resources rather than waste. When discharged, end-of-life materials still possess properties that can be exploited. For this reason, a comprehensive characterization of reusable materials is mandatory to reduce waste and increase material availability. The reuse of waste materials, such as surgical masks, is of particular interest in giving people in disadvantaged contexts the opportunity to self-produce and self-install panels within their homes, with the dual result of improving indoor comfort and increasing human capital. This paper focuses on the identification of a possible second application for surgical face masks through experimental characterization. Panels made of masks were tested for water vapor permeability, thermal conductivity, and fire resistance and their use as insulating material in the building sector was discussed. Based on the results, surgical face masks are suitable as thermal insulating materials, do not pose safety concerns, and can reduce energy consumption and improve thermal comfort when installed indoors. [ABSTRACT FROM AUTHOR]

Progressive climate changes, drought resulting from them and the prospect of problems with access to water for people in cities mean that actions are being taken to minimize water use in buildings and to implement a circular economy in the water and wastewater sector. Within the water circular economy model, there is also a stage of "water consumption". Minimizing water use in buildings undoubtedly has a number of advantages. However, it should be borne in mind that it may also have weaknesses, and if implemented on a large scale, it may be associated with certain threats. For these reasons, the aim of this paper is to critically analyze the possible directions of water management in buildings in order to reduce water consumption and increase the efficiency of its use. As part of the introduction, the model "towards a water circular economy for households" is presented and the possibilities of minimizing water consumption in buildings are discussed. The prospects for reducing the consumption of tap water are discussed in terms of existing opportunities, but also threats, barriers and limitations. A SWOT analysis of the implementation of drinking-water consumption reduction in cities is presented. The challenges faced by engineers, constructors, policy makers and consumers, and the potentialities for the development of this stage of the water life cycle, are considered. The conclusions summarize the current state and perspectives of water management in buildings. Based on the conducted analysis, suggested directions of activities for cities of the future in the technical, technological as well as socio-economic fields are indicated. There should be broad-based education, and efforts should be made to change the approach to designing and developing new guidelines. The implementation of minimizing water consumption should be accompanied by the control of possible negative effects and actions to mitigate them. In the transformation towards clean and available energy, future success should be seen in minimizing the consumption of drinking water in buildings. [ABSTRACT FROM AUTHOR]

It is a well-known issue that the 2050 target of carbon emissions neutrality will be reached only with the co-operation of all the interested sectors, and the construction sector could be one of the main contributors to this change. With the built environment globally responsible for about 40% of annual global energy-related CO2 emissions, the construction sector offers an important opportunity to drive transformative change and presents the most challenging mitigation potential among all industrial sectors, which also brings opportunities for adopting sustainability practices and increasing resilience. This paper presents a systematic literature review of those two pivotal concepts to reach the decarbonization goal: sustainability and resilience. Starting from an extensive literature review (2536 scientific documents) based on the PRISMA statement, the definitions and assessment methodologies of those concepts for the construction sector have been studied. The methodological approach followed for their analysis has been conducted on a first selection of 42 documents, further reduced to 12 by using clear inclusion criteria to identify the integrated assessment procedures. The main goal of this study is to clarify the correlation between sustainability and resilience concepts for constructions and their integrated assessment, in line with the latest regulations and market needs. The results show that, currently, sustainability and resilience are mainly evaluated in a distinct way to obtain building energy performance certificates, as well as to quantify the building market value and its complementary contribution to the 'energy efficiency first' principle and energy-saving targets towards the emergent issue of climate change. Few works focus on the integrated assessment of both concepts considering the construction industries' point of view about materials and/or systems for buildings. The novelty of this study is the critical review of the current sustainability and resilience integrated assessment methods used for the construction value chain, declined for four main target groups. Researchers, policymakers, industries, and professionals could gain dedicated insights and practical suggestions to put in practice the elements of circular economy, ecological innovation, and cleaner production, which are essential in order to drive the decarbonization of the built environment. [ABSTRACT FROM AUTHOR]

According to the European Energy Efficiency Directive for Buildings, member states are required to develop long-term strategies to adopt more sustainable, secure, and decarbonized energy systems in buildings by 2050. In this line of approach, an optional common regime has been established to define and calculate the smart readiness of buildings and assess their ability to adapt their operation to the needs of the occupants and the network. Thus, the smart readiness indicator (SRI) emerged, which assesses technological readiness by examining the presence and evaluation of the functionality level of various smart services, aiming at energy savings, the ability of the building to respond to users' needs, and energy flexibility. This paper focuses on examining the SRI calculation methodology's application to an office building, which is currently being deeply renovated. Initially, there is an analysis of the SRI, its calculation methodology, and its goals. This is followed by the practical calculation part of the SRI for a typical office building located in Greece and belonging to the climate zone of southern Europe. The results indicate that the SRIs application is not a straightforward issue since parameters that need to be considered are not regulated to the same degree. On the other hand, SRI can provide a stimulus for exploiting the renovation potential of buildings, precisely by integrating the various aspects and linking those to the use of innovative technologies. [ABSTRACT FROM AUTHOR]

Solar energy has gained prominence because of the increasing global attention received by renewable energies. This shift can be attributed to advancements and innovations in solar cell technology, which include developments of various photovoltaic materials, such as thin film and tandem solar cells, in addition to silicon-based solar cells. The latter is the most widely commercialized type of solar cell because of its exceptional durability, long-term stability, and high photoconversion efficiency; consequently, the demand for Si solar cells has been consistently increasing. PV modules are designed for an operation lifespan of 25–30 years, which has led to a gradual increase in the number of end-of-life PV modules. The appropriate management of both end-of-life and prematurely failed PV modules is critical for the recovery and separation of valuable and hazardous materials. Effective methods for end-of-life PV waste management are necessary to minimize their environmental impact and facilitate transition to a more sustainable and circular economy. This paper offers a comprehensive overview of the separation processes for silicon PV modules and summarizes the attempts to design easily recyclable modules for sustainable solar module development. Based on the studies summarized in this paper, suggestions are provided for future research. [ABSTRACT FROM AUTHOR]

Waste-to-energy processes remain essential to ensure the safe and irreversible removal of materials and substances that are (or have become) unsuitable for reuse or recycling, and hence, to keep intended cycles of materials in the circular economy clean. In this paper, the behavior of inorganic compounds in waste-to-energy combustion processes are discussed from a multi-disciplinary perspective, against a background of ever tightening emission limits and targets of increasing energy efficiency and materials recovery. This leads to the observation that, due to the typical complexity of thermally treated waste, the intelligence of combustion control systems used in state-of-the-art waste-to-energy plants needs to be expanded to better control the behavior of inorganic compounds that typically end up in waste furnaces. This paper further explains how this goal can be achieved by developing (experimentally validated) predictive numerical models that are engineering-based and/or data-driven. Additionally, the significant economic potential of advanced thermochemical intelligence towards inorganic compounds in waste-to-energy combustion control systems is estimated on the basis of typical operational figures. [ABSTRACT FROM AUTHOR]

Recent years have observed a reconstruction of the waste management system from a linear resource flow economy to a circular economy. This approach is reflected in the provisions of the Waste Framework Directive (2018), which introduces, among others, new recycling targets for municipal waste which require, by 2025, 55% of the municipal waste to be recycled, in 2030—60%, and in 2035—65%. The ambitious targets adopted for preparing for the reuse and recycling of municipal waste will not be achieved without a high level of the recycling of bio-waste. This paper studies the quantification of municipal waste and nitrogen in a circular municipal waste management system (MWM) implemented for a city of 100,000. It was assumed that MWM would meet the requirements in terms of EU and Polish circular waste management goal legislation for the years 2025, 2030 and 2035. The research results showed that the development of a separate waste collection will reduce the waste delivered to MBT. The required MBT capacity will decrease by almost 2.4 times. Moreover, it has been shown that the introduction of a closed-loop MWM will result in an almost two-fold reduction in the amount of nitrogen going to the landfill and an increase in the mass of nitrogen that can be used to fertilize the soil (by approximately 22%). Furthermore, it has been shown that the most favorable option for an organic waste treatment is the anaerobic–aerobic process. This solution provides the highest biogas production and the lowest nitrogen gas emissions to air. [ABSTRACT FROM AUTHOR]

The present work is a critical review on the carbon footprint and energy recovery potential of septic and Imhoff tanks for primary wastewater treatment. From an online search of research papers, a lack of up-to-date research about gas emissions from Imhoff tanks emerged. Additionally, available literature data should be extended to incorporate the effect of seasonal variations, which may be relevant due to the fact that both systems work under environmental conditions. The literature generally agrees on the positive effect of temperature increase on biogas and methane production from both septic and Imhoff tanks. Additionally, sludge withdrawal is an important operational feature for gas production in these reactors. More recently, the application of electrochemical technologies and the installation of photovoltaic modules have been studied to enhance the sustainability of these decentralized solutions; in addition, sludge pretreatment has been investigated to raise the obtainable methane yields due to limited sludge biodegradability. Further research is needed to assess the effective sustainability of biogas collection and valorization from existing septic and Imhoff tanks, considering the limited biogas generation and the implementation of these systems in decentralized wastewater treatment scenarios (rural or mountain areas). Contrary to the intensive research on greenhouse gas mitigation strategies applied to centralized systems, solutions specifically designed for gas emission mitigations from septic and Imhoff tanks have not attracted the same scientific interest up to now. More generally, given the widespread application of these two options and their potential significant contribution to the overall carbon footprint of wastewater treatment technologies, much more research must be performed in the future both on the quantification of gas production and on the applicable strategies to reduce their carbon footprint. [ABSTRACT FROM AUTHOR]

Implementing blockchain technology in waste management is a novel approach to environmental sustainability and accountability challenges in our modern world. Blockchain, a technology that enables decentralized and immutable ledgers, is now being re-imagined as a tool to revolutionize waste management. This innovative approach aims to improve waste management transparency, traceability, and efficiency, resulting in significant environmental and economic benefits. In traditional waste management systems, the tracking and disposal of waste materials are not transparent and can be vulnerable to fraud, mismanagement, and inefficiency. Blockchain technology provides a secure and transparent platform for recording every step in the waste management lifecycle, from waste generation to collection, transportation, recycling, or disposal. Every transaction in the blockchain is recorded in a tamper-proof manner, enabling real-time monitoring and verification of waste-related data. This paper introduces the concept of using blockchain technology in waste management. The main goal of this work is to show the implementation of blockchain technology in an existing waste management company, using smart contracts in the recycling process to provide transparency. Also, the digital product passport was redefined in terms of circular economy and waste recycling. [ABSTRACT FROM AUTHOR]

Reducing emissions from fluorinated gases (F-gases) is considered one of the key conditions for the European Union (EU) to be able to meet the requirements of the European Green Deal, primary objectives of which are the reduction in greenhouse gas emissions by at least 55% by 2030 compared to 1990 and the gradual transition to net climate neutrality by 2050. To this end, a quota system for hydrofluorocarbons (HFCs) is already in place, introduced through the updated F-Gas Regulation (517/2014). The aim of this paper is to review an innovative scheme currently under development that strongly promotes the Recovery, Recycling and Reuse (3R) of F-gases extracted from the heating, ventilation, air conditioning and refrigeration (HVAC-R) equipment of the building sector, thus offering a sustainable alternative source for refrigerant supplies. Therefore, the basic operating principles of the so-called "3R ECOSYSTEM" are outlined and especially its three main components, which are: the self-certification/self-declaration platform, the F-gas identification and recycling units (prototypes) and the Retradeables marketplace. In addition, an overview of both the demonstration phase and the scheduled replication phase of the 3R ECOSYSTEM is provided, including the estimated impact on carbon dioxide (CO2) savings due to the progressive uptake of the circular use of existing F-gases across Europe. [ABSTRACT FROM AUTHOR]

This paper presents a methodology to select the most exciting business models based on renewable energy and circular economy technologies within end-of-life coal mines to help develop a renewable-based energy sector, promote sustainable local economic growth, and maximise the number of green and quality jobs. To achieve this goal, first, a structural analysis was developed to select the technical variables that better identify this complex system. Second, a morphological analysis allowed the construction of the scenario space. Third, a multicriteria assessment was developed to achieve this goal, based on the previously assessed relevant scenarios, considering the European Green Deal policies, technical variables that characterise end-of-life coal mine environments, technology readiness level, the European taxonomy, synergistic potentials, contributions to the circular economy, and sector coupling. Finally, result indicators were selected to analyse the alternative options derived from the justification approach, considering the targets set by the European Green Deal and related taxonomy and the regional policy indicators for the Just Transition Fund. The results show that eco-industrial parks with virtual power plants represent the most appropriate business model choice, according to the scoring given to the different aspects. They may be complemented by a hydrogen production plant, provided that specific economic subventions are obtained to achieve balanced financial results. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants are considered to be not only as treatment facilities, but also essential elements of the circular economy. Wastewater treatment plants can be essential chains of the circular economy cycle. Despite this, sewage sludge management and utilization are mostly limited to biodegradation and further agricultural uses or incineration. The recovery of valuable products is mainly limited to nitrogen and phosphorus compounds. Fewer analyses focus on generating, recovering, and removing various polymers from sewage sludge, such as cellulose or extracellular polymeric substances (EPS). On the other hand, sewage sludge also contains polymeric pollutants, such as microplastics. The recovery and use of biopolymers is significant considering the problems connected with the presence and effects of artificial polymers (microplastics) in the environment. Despite the technical possibilities, not many technical scale installations are operated. Law regulations should make some incentives to develop the technologies and sell the recovered polymers in the market not as waste material, but as a valuable product. This paper presents state-of-the-art technologies for selected polymers' recovery from sludge, including technical parameters of the processes and possible applications of recovered products, but it also considers the possibility of microplastics' removal from this waste material. [ABSTRACT FROM AUTHOR]

Environmental problems associated with global energy supply systems and the increasing amount of global solid waste production are triggering a shift towards a greater reliance on biomass waste. Waste-to-energy systems have become important for industries and scientists because of the increasing interest in energy production from waste, due to improved efficiency and cost-effective solutions. The shift to biomass is also essential for industries to use their own waste to produce their own energy, which is in line with circular economy concepts. This Special Issue "Biomass Wastes for Energy Production" of Energies comprises ten (10) papers, including one review article, that represent the latest advances of waste-to-energy technologies and contribute to the rethinking of global energy supply systems. The Guest Editor also highlights other relevant topics that fall beyond the coverage of the published articles. [ABSTRACT FROM AUTHOR]

This paper assesses the primary energy and environmental impacts of a restaurant main course product's lifecycle, especially focusing on end-of-life (EoL) stage. In the first step, a cradle-to-grave complex life cycle assessment (LCA) model of the product has been set up from the extraction of the required raw materials through the preparation, cooking and use phase to the end-of-life. In the second step, three scenarios (landfilling, incineration, and composting) were compared for the generated food waste in the end-of-life stage given that one of the biggest challenges in waste management is the optimal management of food waste. We calculated eleven environmental impact categories for the examined food product with the help of GaBi 9.0 software. During our research work, the primary energy was examined in each phase. In the third step, a comparison between the traditional and "sous vide" cooking technologies has been created to optimise of the cooking/frying life cycle phase. This paper basically answers three main questions: (1) How can the main environmental impacts and primary energy throughout the whole life cycle of the examined product be characterised? (2) What methods can optimise the different life cycle stages while reducing and recycling energy and material streams? and (3) what is the most optimal waste management scenario at the end-of-life stage? Based on the analysis, the highest environmental impact comes from the preparation phase and the end-of-life scenario for the traditional incineration caused almost twice the environmental load as the landfilling of the food waste. Composting has the lowest environmental impact, and the value of the primary energy for composting is very low. The sous vide cooking technique is advantageous, and the continuously controlled conditions result in a more reliable process. These research results can be used to design sustainable cooking and catering with lower environmental impacts and energy resources in catering units. [ABSTRACT FROM AUTHOR]

Biomass gasification has obtained great interest over the last few decades as an effective and trustable technology to produce energy and fuels with net-zero carbon emissions. Moreover, using biomass waste as feedstock enables the recycling of organic wastes and contributing to circular economy goals, thus reducing the environmental impacts of waste management. Even though many studies have already been carried out, this kind of process must still be investigated and optimized, with the final aim of developing industrial plants for different applications, from hydrogen production to net-negative emission strategies. Modeling and development of process simulations became an important tool to investigate the chemical and physical behavior of plants, allowing raw optimization of the process and defining heat and material balances of plants, as well as defining optimal geometrical parameters with cost- and time-effective approaches. The present review paper focuses on the main literature models developed until now to describe the biomass gasification process, and in particular on kinetic models, thermodynamic models, and computational fluid dynamic models. The aim of this study is to point out the strengths and the weakness of those models, comparing them and indicating in which situation it is better to use one approach instead of another. Moreover, theoretical shortcut models and software simulations not explicitly addressed by prior reviews are taken into account. For researchers and designers, this review provides a detailed methodology characterization as a guide to develop innovative studies or projects. [ABSTRACT FROM AUTHOR]

Slowing down replacement cycles to reduce resource depletion and prevent waste generation is a promising path toward a circular economy (CE). However, an obligation to longevity only sometimes makes sense. It could sometimes even backfire if one focuses exclusively on material resource efficiency measures of the production phase and neglects implications on the use phase. The (environmental) lifespan of circular products should, therefore, be optimized, not maximized, considering all life cycle phases. In this paper, a generic method for determining the optimal environmental lifespan (OEL) of energy-using products (EuPs) in a CE is developed, allowing the simultaneous inclusion of various replacement options and lifetime extension processes, like re-manufacturing, in the assessment. A dynamic programming approach is used to minimize the cumulative environmental impact or costs over a specific time horizon, which allows considering an unordered sequence of replacement decisions with various sets of products. The method further accounts for technology improvement as well as efficiency degradation due to usage and a dynamic energy supply over the use phase. To illustrate the application, the OEL of gas heating appliances in Germany is calculated considering newly evolved products and re-manufactured products as replacement options. The case-study results show that with an average heat demand of a dwelling in Germany, the OEL is just 7 years for climate change impacts and 11 years for the aggregated environmental indicator, R e C i P e e n d p o i n t (t o t a l) . If efficiency degradation during use is considered, the OEL for both environmental impact assessment methods even lowers to 1 year. Products are frequently replaced with re-manufactured products to completely restore efficiency at low investment cost, resulting in higher savings potential. This not only implies that an early replacement before the product breaks down is recommended but also that it is essential to maintain the system and, thus, to prevent potential efficiency degradation. The results for cost optimization, as well as currently observed lifespans, vary considerably from this. [ABSTRACT FROM AUTHOR]

Plastics follow a linear economic structure, leading to detrimental environmental effects, such as global warming and ecosystem destruction, through incineration and accumulation throughout their life cycle. This study examined the types, potential generation amounts, and properties of recycled plastics from waste electrical and electronic equipment (WEEE) to assess the feasibility of the closed-loop recycling of plastics from WEEE under South Korea's EPR system. Actual data from companies were used to determine the factors, such as the processing volume of WEEE. As of 2021, acrylonitrile-butadiene-styrene (53,363 tons), polypropylene (14,320 tons), and polystyrene (8199 tons) were the recycled plastics produced by both large and small WEEE. The properties of recycled plastics meet the specifications of new electrical and electronic products. In addition, an analysis using Life Cycle Assessment (LCA) methodology showed that the recycling effect (avoided emissions) reached 262,033 tons of CO2 eq. per year. Therefore, closed-loop recycling is the most suitable and effective method for reducing greenhouse gases. This paper presents the potential amount of recycled plastics generated from WEEE within South Korea's regulatory framework, providing valuable foundational data for policy development for promoting the use of recycled plastics. [ABSTRACT FROM AUTHOR]

The use of bio-based building materials as an alternative to replacing concrete or insulation materials is called to become a growing trend in the construction industry. On Science direct, publications concerning "bio-based materials" have increased from 4 in 2002 to 1073 twenty years later, demonstrating a growing interest in these materials However, among bio-based materials, crop or plant-based materials are not as popular. Due to their relative novelty, little is known about their potential applications, physical characteristics, and environmental impacts. The aim of this review is to qualitatively investigate the technical and environmental viability of crop-based materials in modern building applications. The specific objectives of the study consider greenhouse gas (GHG) emissions using life cycle assessment (LCA) approaches, contribution to the circular economy, and physical and hygrothermal characteristics. Another objective is to examine the progress of crop-based materials' R&D, current bottlenecks, and a future roadmap for their evolution in state-of-the-art renewable buildings. The paper is broad enough to capture a large readership rather than experts in the domain. The review reveals that crop-based materials have the potential to replace traditional, highly emissive building materials. They offer low environmental impacts, in all stages of their life cycle. [ABSTRACT FROM AUTHOR]

Considering the current geopolitical situation that has hindered the gas supply gas from Russia, Europe's main supplier, it is necessary to find alternative routes to guarantee the Italian gas stocks in winter at a reasonable cost. Such energetic strategies should consider the environmental sustainability of the different available options, fitting the targets of the EU environmental policy. With the aim of supplying a quantitative tool to support the European green transition, this paper reports the entire life cycle assessment (LCA) of three different options for the production and supply of natural gas/methane in Italy: the production of biomethane from biogas (considering a real-scale plant in Italy), the use of liquefied natural gas (LNG) supplied by Qatar by vessel, and the use of compressed gas delivered from Algeria via pipeline. The application of the LCA standardized method allowed for the quantification of the environmental benefit provided by the first option, against all the considered impact categories, thanks to a combination of several advantages: (a) its low-impact anaerobic production, (b) its exploitation of a waste product from the food/agriculture industries, and (c) its production of valuable by-products, which can be considered environmental credits. The results proved the possible environmental gain resulting from an integrated energy supply system that would be able to enhance the economic fabric of specific areas. [ABSTRACT FROM AUTHOR]

Nowadays, the main challenge for industrial and municipal enterprises is related to the tightening regulations and recommendations regarding environmental protection, which have been included in the circular economy (CE) package. Enterprises from all sectors, including water and sewage management, are obliged to actively participate in the CE transition. Modern wastewater treatment plants (WWTPs) should include actions aimed at a more sustainable use of available resources (water, energy, raw materials) to contribute to the protection of natural resources. In this way, they can be treated as resource facilities. This paper proposes a conceptual framework for a 'Wastewater Treatment Plant of the Future' that includes several technological solutions that take into account circular management of waste streams generated in WWTPs, such as wastewater (WW), sewage sludge (SS) and sewage sludge ash (SSA). Many actions have been already taken to modernize and build WWTPs that can respond to current and future challenges related to environmental protection. In the case of a CE 'Wastewater Treatment Plant of the Future', the recovery of water, energy and raw materials from available waste streams is strongly recommended. The implementation of CE solutions in analyzed facilities is incorporated into many strategies and policy frameworks, such as national and international (including European) documents. The proposed CE solutions could indirectly contribute to satisfying significant technological, social and environmental needs of the current and future generations, which is in line with sustainability principles. [ABSTRACT FROM AUTHOR]

In recent years, new energy power generation has been widely used. As household energy storage will be widely promoted in the future, many households' energy storage will soon need to be replaced. It is of great significance to study the recycling of household energy storage to reduce environmental pollution and promote the sustainable development of the household energy storage market. However, the lack of research on the design of household energy storage and recovery network from the perspective of manufacturing enterprises hinders the sustainable development of household energy storage. Based on the above, a household energy storage recycling model considering carbon emissions was established in this paper. This model evaluated the recovery status of household energy storage online through a big data platform and proposed three different recovery schemes based on the evaluation results. Through a case study of Sichuan and Chongqing, the overall profit of the household energy storage and recycling system could be increased by about CNY 1.61 million, while reducing about 1.04 hundred tons of carbon emissions, thus verifying the feasibility and effectiveness of the model. In addition, the results of scenario analysis showed that the processing cost and demand are the main factors affecting the optimal design of the recycling network, and they can change the configuration of the network. Appropriate processing methods, locations, and transportation schemes would decrease the cost of production and carbon emissions. Household energy storage is possible for recycling residual values that decrease carbon emissions during storage. At the same time, further improving more efficient recycling technology is an important idea to increase the profits of household energy storage manufacturers. [ABSTRACT FROM AUTHOR]

The idea of a circular economy (CE) has gained ground over the past ten years as a means of addressing sustainable development and getting around the limitations of the current and linear dominant production and consumption patterns. The primary goal of a CE is to encourage the adoption of closing-the-loop production methods to improve resource use efficiency, modify chemical processes, and increase product and material lifespan. According to the 2030 Agenda for Sustainable Development, which focuses on 17 Sustainable Development Goals, 14 of which call for the appropriate application of green chemistry (GC) concepts and patterns, the role that chemistry may play in the shift toward more sustainable models is critical. By serving as the foundation for novel products made from renewable feedstocks and designed to be reused, recycled, or recovered with the associated minimum energy requirements, green and sustainable chemistry could be the key to unlocking the economic potential of the CE toward new product design and ultimately solving waste management problems. The aim of this perspective paper, while using a variety of literature sources, is to essentially capture the main issues associated with the CE and GC paradigms and how these two approaches can merge toward sustainable business models and the production of new materials. This integration focuses on reducing waste, conserving resources, and minimizing negative environmental impacts, while also considering economic viability. However, the obstacles to achieving implementation of the CE and GC principles are investment, environmental education, and legislation. To advance toward the circular economy and green chemistry, international agreements should be reconsidered to provide an appropriate framework, including the creation of incentives for businesses and individuals to adopt circular practices, the establishment of education programs to promote the benefits of circular practices, and the development of regulations to support the transition to sustainable production and consumption patterns. [ABSTRACT FROM AUTHOR]

A lead acid battery is an old renewable battery that is usually discharged to deliver a high surge current to ignite a petrol-based engine. Nowadays, there are different improved versions of lead acid batteries that can deliver high energy densities with low maintenance costs. As the batteries are charged and discharged repeatedly over time, the amount of lead sulfate across the electrode plates grows, reducing the total surface areas of the plates and, thus, the rate of ionization between the electrolyte and the plate surfaces. The batteries then eventually come to the end of their service lives. Even with the improved versions, lead acid batteries are usually discarded at their retirement. However, if the retired batteries can be used for other purposes, the circular economy of the batteries can be improved significantly. It is therefore necessary to study the physical characteristics of the retired batteries and explore means of improving their charging and discharging capabilities. This paper presents research on improving the storage capability of retired lead acid batteries by applying different charging voltages across them. The results show that the electrode plates of the retired batteries become porous when a high charging voltage is applied, hence increasing the total surface area of the plate surfaces. The storage capability of the batteries is improved because the accumulated lead sulfate is removed from the electrode plates by the high charging voltage. As a result, the rate of ionization is increased, hence restoring the storing capability of the retired batteries to up to 71–89% of the original capacity rating. [ABSTRACT FROM AUTHOR]

Information technologies possess the significant potential to improve the efficiency of resources and optimize energy usage, as well as make a significant contribution to the sustainable circular economy (CE). The concept of digital sufficiency provides a framework for understanding how information technology can be part of significant achievements in the circular economy, especially when embraced by business companies. Moreover, the possibility of the implementation of closed-loop resources has become possible with the development of digital manufacturing technologies. However, the research of establishing the CE in SMEs, especially in fossil-energy-abundant countries, such as the Russian Federation, is quite limited. Our paper fills in this gap by studying the adoption of CE practices as well as the investments for promoting CE in Russian SMEs through such factors as the existence of R&D, bank loans, and access to grants at the national and international level. It achieves this based on the data sample of 314 managers of Russian SMEs. Our results demonstrate that the investment or existence of R&D in SMEs and knowledge of CE as well the governmental funding and access to wider markets all together tend to have a significant and positive effect on implementing and investing into CE in SMEs, while the administrative barriers yield a small but negative effect. These results might be helpful for the relevant stakeholders in order to identify factors catalyzing attention from both the SMEs engaged in CE transitions, as well as help the decision makers wishing to foster the transformation of the SMEs to a circular economy. We can conclude that supporting SMEs (both financially and via increasing their public awareness) to make their own transitions towards CE has a societal effect that can speed up a greener transition and significantly contribute to increasing energy efficiency. [ABSTRACT FROM AUTHOR]

The tanning industry generates significant amounts of solid waste and post-production wastewater, which should be managed in accordance with the principles of the circular economy. Waste is generated at various technological stages of production. This comprises mainly solid waste and leachate. A comprehensive solution to the problem of disposal of this waste is very important from economic and environmental points of view. This work presents research for a technological production line designed for the comprehensive processing of post-production residues. In the present paper, the authors present an analysis related to the possibility of processing leather flesh side (mizdra) as a substrate for methane fermentation. The study showed an increased biogas production from solid waste after enzymatic hydrolysis up to 248 Nm3/Mg. Preliminary research on the system designed for pre-treatment of sewage from the technological line is also presented. The study showed a COD reduction of more than 30%. The possibility of energy management of the solid fraction directly from the processes carried out is demonstrated. [ABSTRACT FROM AUTHOR]

Enhancing carbon emission mitigation and carbon utilization have become necessary for the world to respond to climate change caused by the increase of greenhouse gas concentrations. As a result, carbon capture, utilization, and storage (CCUS) technologies have attracted considerable attention worldwide, especially in China, which plans to achieve a carbon peak before 2030 and carbon neutrality before 2060. This paper proposed six priorities for China, the current world's largest carbon emitter, to achieve its dual carbon strategy in the green energy transition process. We analyzed and summarized the challenges and potentialities of conventional carbon utilization (CU), carbon capture utilization (CCU), and CCUS. Based on the current development trend, carbon dioxide capture, circular utilization, and storage (CCCUS) technology that integrates carbon circular utilization and partial sequestration, with large-scale underground energy storage were proposed, namely biomethanation. Technically and economically, biomethanation was believed to have an essential contribution to China's renewable energy utilization and storage, as well as the carbon circular economy. The preliminary investigation reveals significant potential, with a corresponding carbon storage capacity of 5.94 × 108 t~7.98 × 108 t and energy storage of 3.29 × 1012 kWh~4.42 × 1012 kWh. Therefore, we believe that in addition to vigorously developing classical CCUS technology, technical research and pilot projects of CCCUS technology that combined large-scale underground energy storage also need to be carried out to complete the technical reserve and the dual-carbon target. [ABSTRACT FROM AUTHOR]

The use of energy from waste can be a key means of reducing the consumption of fossil fuels and thus reduction of greenhouse gas emissions. Waste energy can be a worthy alternative to conventional energy sources in construction. This paper presents data on energy consumption for the preparation of domestic hot water in residential buildings. A review of the literature sources and inventions in the area of waste energy recovery from grey water was carried out. It also presents the results of research on prototypes of devices used to receive energy deposited in wastewater, published in recent years. The benefits of using drain water heat recovery systems for preheating utility water in residential buildings are presented. An analysis of technical solutions for grey water energy collection units was made, revealing their advantages and disadvantages. Great importance was attached to the review of patent sources as well as devices available on the market. According to the authors, the results of the technical review may be useful for contractors and designers of heat recovery equipment and installations, researchers and potential users of these technologies. [ABSTRACT FROM AUTHOR]

Recent years have brought significant evolution and changes in wastewater treatment systems. New solutions are sought to improve treatment efficiency, reduce investment/operational costs, and comply with the principles of circular economy and zero waste. Microbial granules can serve as an alternative to conventional technologies. Indeed, there has been fast-growing interest in methods harnessing aerobic (AGS) and anaerobic (AnGS) granular sludge as well as microbial-bacterial granules (MBGS), as evidenced by the number of studies on the subject and commercial installations developed. The present paper identifies the strengths and weaknesses of wastewater treatment systems based on granular sludge (GS) and their potential for energy production, with a particular focus on establishing the R&D activities required for further advance of these technologies. In particular, the impact of granules on bioenergy conversion, including bio-oil recovery efficiency and biomethane/biohydrogen yields, and bioelectrochemical systems must be assessed and optimized. [ABSTRACT FROM AUTHOR]

Compostable packaging is one of the innovative alternatives to conventional packaging. This is also an opportunity in view of the current energy crisis and rising oil prices, firstly, because compostable packaging is produced only from renewable resources, and secondly, it can feed both the composting process and biogas plants. According to the CE principles, it is vital to effectively close product life cycles. Therefore, this paper is aimed at expounding the triggering role of social innovations co-created by stakeholders for improving compostable packaging waste management in accordance with the CE concept. The research procedure consisted of four integrated research phases. A qualitive study was undertaken by conducting 29 in-depth interviews and 3 Social Innovation Labs, engaging 67 bio-packaging market stakeholders, which are national and international companies (e.g., manufacturing, distributing), institutions and other organisations from the social, public and private sectors. The results show that one of the key problems for the development of the CE compostable packaging market is the low level of compostable waste packaging management. Its detailed analysis showed that this problem is associated with several barriers and their numerous causes. According to stakeholders, this can be effectively minimised by applying three social innovations that when combined stimulate all elements of waste management, moving it to a higher level of development. [ABSTRACT FROM AUTHOR]

The aim of this article is to analyze the effectiveness of the Extended Producer Responsibility (EPR) concept for packaging in the context of the transition to a Circular Economy (CE) and the corresponding transformation of the energy sector. The functioning of today's packaging industry is becoming more and more linked to the assumptions of the CE due to the use and recycling of raw materials. The basic research method used in this work is an analysis of the literature on the links between the concept of the EPR and the CE. The authors limited their research to the selected legal, economic and social aspects of packaging production and management in the European Union (EU). The situation in Poland is discussed in particular and the legal, economic and social specificity of the implementation of the EPR in this country is presented. This paper emphasizes the dependance between the implementation of the EPR concept and the effectiveness of the transformation toward a CE, which is achieved by increasing the circularity in the energy sector. [ABSTRACT FROM AUTHOR]

A complex method developed to assess quality within a proposed framework and at a certain scope of measurement for circular economy (CE) quality indicators is presented. This was used to compare three different scenarios for municipal waste management systems: 1—incineration; 2—recycling and reuse of separated municipal waste and the transformation of the organic fraction into biodiesel and bio-coal; and 3—an upgraded Scenario 2 including decreased recycling of waste streams and the bioprocessing of paper/cardboard and processing the non-recycled fraction into bio-diesel, bio-coal, and second-generation biofuel. For the evaluation of the CE quality indicator, a set of technical, environmental, economic, and social elements was selected by a panel of experts, who also assigned them a qualitative assessment and weighting on the basis of the factors identified. The calculated Relative Increase in the CE indicator for the scenarios analyzed showed that Scenarios 3 and 2 are much more beneficial than Scenario 1 in technical, environmental, economic and social terms. [ABSTRACT FROM AUTHOR]

Fertilization is an essential element in plant cultivation. Supplying the right amounts of nutrients allows plants to grow and develop. Due to the rising price of mineral fertilizers, other fertilizers and soil conditioners are growing in importance. One of these is the digestate produced in agricultural biogas plants. Due to its properties, the digestate can be used directly as a fertilizer. In this case, the effects of application can both change the soil environment and directly affect plant growth. Physical, biological, and thermal transformations can also produce products based on the digestate or its fractions, which can be successfully used for fertilizer purposes. Among other things, this paper discusses the production and use of composts, biocarbon, and/or fertilizer granules from the solid fraction of the digestate. Numerous scientific studies, including the authors' own research in this article, indicate that digestate can be successfully used as fertilizer, both without processing and with selected methods of treatment. However, further research is needed—especially on the diversity of raw materials used for biogas production and their effects on the composition and performance of the digestate. In addition, research should continue on the processing of digestate into specific products, depending on the needs of soils and plants. [ABSTRACT FROM AUTHOR]

Since it first appeared in literature in the early nineties, the Circular Economy (CE) has grown in significance amongst academic, policymaking, and industry groups. The latest developments in the CE field have included the interrogation of CE as a paradigm, and its relationship with sustainability and other concepts, including iterative definitions. Research has also identified a significant opportunity to apply circular approaches to our rapidly changing industrial system, including manufacturing processes and Industry 4.0 (I4.0) which, with data, is enabling the latest advances in digital technologies (DT). Research which fuses these two areas has not been extensively explored. This is the first paper to provide a synergistic and integrative CE-DT framework which offers directions for policymakers and guidance for future research through a review of the integrated fields of CE and I4.0. To achieve this, a Systematic Literature Review (SLR; n = 174) of the empirical literature related to digital technologies, I4.0, and circular approaches is conducted. The SLR is based on peer-reviewed articles published between 2000 and early 2018. This paper also summarizes the current trends in CE research related to manufacturing. The findings confirm that while CE research has been on the increase, research on digital technologies to enable a CE is still relatively untouched. While the "interdisciplinarity" of CE research is well-known, the findings reveal that a substantial percentage is engineering-focused. The paper concludes by proposing a synergistic and integrative CE-DT framework for future research developed from the gaps in the current research landscape. [ABSTRACT FROM AUTHOR]

Bioadsorbent, obtained as a result of the processing of bio-waste, has recently gained popularity as a material that adsorbs greenhouse gases, mainly carbon dioxide. Bio-waste, mainly residues from food industry operations, is a waste to be landfilled or composted and can be a potential substrate for bioadsorbent production. Bioadsorbents used for carbon capture must, above all, have low production costs and high adsorption efficiency. This review covers popular bioadsorbents that have been tested for their ability to adsorb carbon dioxide. The paper compares bioadsorbent production methods, physicochemical properties, adsorption isotherms, surfaces, and their porosity. There is a lack of data in the literature on the topic of carbon dioxide adsorption on large-scale plants in the target environment. Therefore, further research needs to fill in the gaps to identify the promised potential of these bioadsorbents. [ABSTRACT FROM AUTHOR]