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Waste paper disposed in landfills notably contributes to greenhouse gas (GHG) emissions and impedes more sustainable, circular alternatives, such as recycling. In Hong Kong, this unsustainable approach is currently dominant as 68% of waste paper products are treated in landfills in 2020. To contextualize the impact of local waste paper management and explore mitigation potentials of circular alternatives, this paper develops a quantitative assessment framework around GHG emissions development trajectories. Combining guidelines of the Intergovernmental Panel on Climate Change (IPCC), national GHG inventories, and local parameters from life cycle analysis, five GHG emissions projections were simulated along the Shared Socioeconomic Pathways (SSPs) until 2060. Most recent baselines indicate that Hong Kong's current waste paper treatment generated 638,360 tons CO 2 -eq in 2020, comprising 1,821,040 tons CO 2 -eq from landfill and 671,320 tons CO 2 -eq from recycling, and −1,854,000 tons CO 2 -eq from primary material replacement. Proceeding along a Business-as-Usual scenario under SSP5, GHG emissions will dramatically increase to a net 1,072,270 tons CO 2 -eq by 2060, whereas a recycling-intensive scenario will lead to a net saving of −4,323,190 tons CO 2 -eq. To complement the quantitative evidence on the benefits of waste paper recycling, field research was conducted to explore the feasibility of circular policy innovation from the perspective of recycling stakeholders. These empirical qualitative and quantitative findings from stakeholders' business routines and material transactions provide crucial indications for policy and institutional innovation: Essentially, for Hong Kong to improve waste paper recycling capacities and facilitate a circular economy (CE), local stakeholders require support via fiscal policy measures (financial subsidies or tax reductions) and infrastructure improvements (delivery access and material storage). In sum, this study employs a novel analytical framework combining original qualitative and quantitative evidence to provide policy innovation towards circular, GHG emission-saving waste paper management. [Display omitted] • A new framework assessing greenhouse gas emissions from waste paper treatment. • Exploring long-term carbon neutrality pathways for managing waste paper. • Using empirical evidence from recycling stakeholders for circular policy innovation. [ABSTRACT FROM AUTHOR]

Pulp and paper industry produces massive amounts of sludge from wastewater treatment, which constitute an enormous environmental challenge. A possible management option is the conversion of sludge into carbon-based adsorbents to be applied in water remediation. For such utilization it is important to investigate if sludge is a consistent raw material originating reproducible final materials (either over time or from different manufacturing processes), which is the main goal of this work. For that purpose, different primary (PS) and biological sludge (BS) batches from two factories with different operation modes were sampled and subjected to pyrolysis (P materials) and to pyrolysis followed by acid washing (PW materials). All the materials were characterized by proximate analysis, total organic carbon (TOC) and inorganic carbon (IC), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and N 2 adsorption isotherms (specific surface area ( S BET )and porosity determination). Sludge from the two factories proved to have distinct physicochemical properties, mainly in what concerns IC. After pyrolysis, the washing step was essential to reduce IC and to considerably increase S BET , yet with high impact in the final production yield. Among the materials here produced, PW materials from PS were those having the highest S BET values (387–488 m 2 g −1 ). Overall, it was found that precursors from different factories might originate final materials with distinct characteristics, being essential to take into account this source of variability when considering paper mill sludge as a raw material. Nevertheless, for PS, low variability was found between batches, which points out to the reliability of such residues to be used as precursors of carbon adsorbents. [ABSTRACT FROM AUTHOR]

Household food waste is increasingly recognised as a global wicked problem for its greenhouse gas emissions, economic damage, and resource loss. Although targeted in the UN's Sustainable Development Goals, countries can only respond according to their capacity. For Australia, national policy has put the pressure on states and territories to divert food waste away from landfill into a nascent circular economy. For councils, this increasingly means implementing a FOGO (Food Organics/Garden Organics) kerbside collection. Despite funding and infrastructure development, many are resisting. Framed by the tenets of policy diffusion, this paper presents the results of a nationwide exploratory survey aimed at identifying how and why council-based waste services staff resist, emulate or lead FOGO implementation. By assessing participants current kerbside systems and their attitudes towards household food waste management, the survey found costs, contamination, and capacity and were key concerns. However, responses to these varied considerably despite similarities of situation, often relating more to collaborative attitudes across waste services, council, and councillors. This paper recognises that a conducive environment for change is urgently needed for Australia to achieve organics diversion targets and shift household food towards a circular economy. It provides a starting point for further research into the complex and nuanced dynamics between council waste services and FOGO implementations, from external drivers and council paradigms to individual attitudes and perceptions. • Policy push alone is not enough to achieve Australia's food waste diversion targets. • Achieving uncontaminated household food waste requires strong national legislation and policy. • Regional collaborations between councils are beneficial yet under-used. • Inter-council emulation enhances infectious inaction where policy and support is lacking. • National food waste awareness-raising reduces community confusion. [ABSTRACT FROM AUTHOR]

An insightful attempt has been made in this review and the primary objective was to meticulously provide an update on the sustainabilities, advances and challenges pertaining the removal of ammonia from water and wastewater. Specifically, ammonia is a versatile compound that prevails in various spheres of the environment, and if not properly managed, this chemical species could pose severe ecological pressure and toxicity to different receiving environments and its biota. The notorious footprints of ammonia could be traced to anoxic conditions, an infestation of aquatic ecosystems, hyperactivity, convulsion, and methaemoglobin, popularly known as the "blue baby syndrome". In this review, latest updates regarding the sustainabilities, advancements and challenges for the removal of ammonia from aqueous solutions, i.e., river and waste waters, are briefly elucidated in light of future perspectives. Viable routes and ideal hotspots, i.e., wastewater and drinking water, for ammonia removal under the cost-effective options have been unpacked. Key mechanisms for the removal of ammonia were grossly bioremediation, oxidation, adsorption, filtration, precipitation, and ion exchange. Finally, this review denoted biological nutrient removal, struvite precipitation, and breakpoint chlorination as the most effective and promising technologies for the removal of ammonia from aquatic environments, although at the expense of energy and operational cost. Lastly, the future perspective, avenues of exploitation, and technical facets that deserve in-depth exploration are duly underscored. [Display omitted] • This paper successfully reviewed potential avenues for ammonia valorization. • Gaps in knowledge and challenges related to ammonia treatment were highlighted. • Challenges related to removal and recovery were duly explained. • Future research outlooks and needs were also emphasized in this paper. • Feasibilities of practicing circular economy in ammonia treatment were identified. [ABSTRACT FROM AUTHOR]

This paper reviews the current problems and prospects to overcome circular water economy management challenges in European countries. The geopolitical paradigm of water, the water economy, water innovation, water management and regulation in Europe, environmental and safety concerns at water reuse, and technological solutions for water recovery are all covered in this review, which has been prepared in the frame of the COST ACTION (CA, 20133) FULLRECO4US, Working Group (WG) 4. With a Circular Economy approach to water recycling and recovery based on this COST Action, this review paper aims to develop novel, futuristic solutions to overcome the difficulties that the European Union (EU) is currently facing. The detailed review of the current environmental barriers and upcoming difficulties for water reuse in Europe with a Circular Economy vision is another distinctive aspect of this study. It is observed that the biggest challenge in using and recycling water from wastewater treatment plants is dealing with technical, social, political, and economic issues. For instance, geographical differences significantly affect technological problems, and it is effective in terms of social acceptance of the reuse of treated water. Local governmental organizations should support and encourage initiatives to expand water reuse, particularly for agricultural and industrial uses across all of Europe. It should not also be disregarded that the latest hydro politics approach to water management will actively contribute to addressing the issues associated with water scarcity. • We concentrated on new future perspectives for addressing current resource recovery strategy challenges. • We revealed a snapshot for future needs for a fully circular European economy. • We built a discussion platform in holistic water recovery by COST Action. [ABSTRACT FROM AUTHOR]

The circular economy (CE) has been gaining traction in recent years as it promises a change for good, in terms of environmental, social, and economic benefits. The major changes required to implement circular economy business models (CEBMs), can prove to be especially difficult for organisations. This study provides a holistic analysis of the effect of CE institutional policies on the development of CEBMs in organisations, by exploring not only production-oriented policies, which have been the focus of previous research, but also consumption policies. Consumption policies, in the form of regulatory and information policies, are oriented towards consumers and have the potential to affect the demand for CE products, which in turn affects the development of CEBMs in organisations. The paper is framed within the institutional theory and the context of the European Union. Our results reveal that consumption policies have a positive, albeit diminishing, effect on the CEBMs. Our paper finds that regulation is the most impactful policy, having a larger impact than production policies. Our results highlight the important role of institutional policies in fostering consumers' demand for CE products and of consumption policies as tools to be employed by governments in fostering CEBMs and achieving sustainability. • Consumption policies have a positive, albeit diminishing, effect on the CEBMs. • Regulation for consumption is more impactful than production policies. • Institutional policies are crucial in fostering consumers' demand for CE products. • Consumption policies are an essential tool for governments to foster CEBMs. [ABSTRACT FROM AUTHOR]

Contaminated recyclables, which are frequently discarded as waste, pose a significant challenge to the implementation of a circular economy. These contaminated recyclables impede the circulation of resources, resulting in higher processing costs at material recovery facilities (MRFs). Over the past few decades, machine learning (ML) models such as linear regression (LR), support vector machine (SVM), and random forest (RF) have evolved to provide new methods for predicting inbound contamination rates in addition to traditional statistical models. In this study, we applied ML models to predict inbound contamination rates using demographic features from 15 counties in the U.S. with different curbside collection strategies. In general, we found that ML models outperformed linear mixed models. Specifically, SVM models had the highest performance (R2 = 0.75; mean absolute error (MAE) = 0.06), which may be due to their ability to model nonlinear relationships between features and inbound contamination rates. The key predictor was population, with poverty rate being positively correlated and median age negatively correlated with inbound contamination rates. To improve the management of contamination and enhance the implementation of a circular economy, better models are needed to understand and estimate inbound contamination rates as well as identify critical factors in the present and future. • We examine the factors influencing inbound paper contamination in MRFs. • Importance of the factors are determined by three machine learning models. • The contamination levels in single stream were found to be higher than that of commingled. • SVM regressor obtained the best performance. • Population size is determined to be the most significant factor by all three ML methods. [ABSTRACT FROM AUTHOR]

This research paper delves into the intricate interplay between decarbonisation and sustainability, focusing on adopting chemical looping technologies. Deep decarbonisation scenarios necessitate a profound transformation in various sectors to mitigate climate change, and oil refineries, as pivotal players, must adapt to these changes. Employing the BLUES integrated assessment model, we evaluate the evolution of the refining sector in decarbonisation pathways, emphasising its potential for sustainability through repurposing and emissions mitigation. Additionally, we delve into chemical looping technologies, including Solar Thermal Chemical Looping (STCL), Reverse Water Gas Shift Chemical Looping (RWGS-CL), Chemical Looping Reforming (CLR), and Super Dry Reforming (SDR), elucidating their principles and contributions to carbon dioxide (CO 2) conversion. These technologies offer promising routes for CO 2 capture and present opportunities for sustainable carbon loop cycles, potentially revolutionising industries' emissions reduction efforts. In a world of climate change, this research illuminates a sustainable path forward by integrating decarbonisation and innovative CO 2 management strategies. • Chemical looping technologies offer innovative routes for sustainable carbon capture and utilisation. • Oil refineries can play a pivotal role in reducing emissions through asset repurposing. • Integration of the BLUES model provides insights into refining sector evolution for decarbonisation. • Solar Thermal Chemical Looping (STCL) utilises solar energy for CO 2 conversion. • Methane-utilising CO 2 CL processes like CLR and SDR offer promising sustainability solutions. [ABSTRACT FROM AUTHOR]

The escalating threat of plastic pollution necessitates urgent and immediate action, particularly within the food and beverage (F&B) industry, a significant contributor to single-use plastic waste (SUP). As the global population surges, so does the consumption of single-use plastics in the F&B sector, perpetuating a linear economy model characterized by a 'take, make, use, dispose' approach. This model significantly exacerbates plastic waste issues, with projections indicating an alarming increase in plastic outputs by 2050 if current practices continue. Against this backdrop, the circular economy presents a viable alternative, with its emphasis on resource retention, recovery, and the extension of product lifecycles. This study delves into the problems posed by single-use plastics, introduces the circular economy as a sustainable model, and explores effective strategies for the recycling and reuse of plastic waste within this framework. By examining the environmental impact of SUP in the F&B sector and advocating for the adoption of circular economy principles, this paper underscores a critical pathway towards sustainable solutions in the battle against plastic pollution. In conclusion, the transition to a circular economy, underpinned by global collaboration and the proactive implementation of supportive policies, is imperative for reducing the environmental footprint of single-use plastics and fostering a sustainable future. • Urgent need to address single-use plastic (SUP) waste in food & beverage industry due to escalating threat. • Growing global population drives linear 'take, make, use, dispose' model, exacerbating plastic waste. • Alarming predictions for SUP output by 2050 necessitate shift to circular economy approach. • Circular economy emphasises resource retention, recovery, and extended product lifecycles as a solution. • Study advocates for circular economy principles in F&B sector to combat plastic pollution crisis. [ABSTRACT FROM AUTHOR]

Abstract This paper discusses the economic rationale of recycling exhaustible raw materials and assesses how a circular economy perspective can improve the sustainable use of critical raw materials (CRMs). We use the case study of yttrium, a rare-earth element (REE) on the EU list of CRMs, given its widespread use in the electronics industry and the geopolitical concentration of its supply. Even if recycling REEs from waste electric and electronic equipment is a valid alternative to extraction from mines, as proposed by the circular economy paradigm, less than 1% of REEs used today are recycled. Nevertheless, studies on the economic benefits of recovery REEs are very limited. In this paper, we present the business case of an Italian recycling company, Relight Ltd., and its HydroWEEE project, to recycle REEs such as yttrium, from spent lamps. In environmental terms, recycling REEs has a much lower impact than their extraction from virgin source. In economic terms, it is profitable to recycle yttrium if its market price is above 14€/kg, and above 9.54€/kg taking in consideration the external costs of mining. Therefore, in 2012 and 2013, recycling was profitable thanks to the high price of yttrium, while between 2014 and 2016 recycling was not cost effective. In these cases, policymakers must incentivize recovery and recycling solutions with appropriate policies. Highlights • In this case study, recycling yttrium is convenient if its market price is above 14 €/kg. • If external costs of mining are considered, recycled yttrium is advantageous above 9.54 €/kg. • In 2012 and 2013 the price of yttrium covered the collection and the treatment costs. • Policymakers should incentivize recycling when market conditions are disadvantageous like in 2014–2016. • To prevent supply risk, it is crucial to sustain the European rare-earth recycling industry. [ABSTRACT FROM AUTHOR]

Abstract "Smart Food Waste Recycling Bin" (S-FRB) systems have recently been developed to facilitate the transformation of food waste into an end-product suitable for use as an energy resource following circular economy principles. This decentralized waste decomposition system utilizes fermentative microorganisms for the treatment of organic food waste and has emerged as a possible solution for coping with both landfill capacity and greenhouse gas emissions issues. This paper utilizes Life Cycle Assessment (LCA) to determine the environmental impacts associated with this S-FRB technology and identify environmental hotspots to reduce these impacts. In this paper, we have conducted an on-site pilot-scale study for 2 months at a canteen located at the City University of Hong Kong, which resulted in a 90% reduction in the mass of food waste treated in the S-FRB system. Based on this pilot-scale study hypothetical scenarios were developed to determine potential environmental impacts potential scaled-up deployments of the S-FRB instrument based on varied assumptions. Examination of the LCAs of these different scenarios demonstrated the potential for further reduction in CO 2 equivalent emissions during food waste treatment. Cumulative Energy Demand (CED) and Energy Return on Investment (EROI) were also investigated to understand the energy balance energy of the S-FRB technology. Finally, using current waste treatment methods in Hong Kong as a benchmark, the environmental impacts of the S-FRB are compared with the conventional food waste treatment approaches such as landfilling and organic waste treatment facilities (OWTF). Graphical abstract Image 1 Highlights • S-FRB technology illustrates lower GHG emission comparing with existing facilities. • Energy return on investment of S-FRB depicts the possibility of food waste circulation. • Optimized scenarios show the improvements in both of GHG emission and EROI. [ABSTRACT FROM AUTHOR]

Abstract A large stream of research has studied the performance of waste plastics impregnated concrete, reporting multiple benefits and advocating its use in construction works. But no study has reported the merits of bricks impregnated with waste plastics. The present paper reports the results of experiments done on bricks made up of varying percentages of waste thermoplastics (0 – 10% by weight) and sand (60 – 70% by weight), holding percentages of fly ash and ordinary Portland cement constant at 15% (by weight) each. Three types of waste thermoplastics were used, forming three separate batches of bricks. The plastics were polycarbonates, polystyrenes, and mixed plastics. The bricks were cured under water for 28 days. Some of the batches were baked at temperatures ranging from 90 °C to 110 °C for 2 hours in order to melt the plastics to form voids. The bricks made with the above-stated compositions were found to possess low thermal conductivity and adequately high compressive strength. The compressive strength of these bricks is observed to be more than 17 MPa, which lies within the upper half of the range of strengths specified for bricks in the IS 1077:1992 standard. The waste plastics impregnated bricks display high thermal resistance, a feature that can add economic value to the brick manufacturers, motivating them to establish the necessary logistics for collection and use of all types of waste thermoplastics. The paper also presents a regression model to predict the compressive strength of bricks at varying plastic contents. The study, thus, introduces a new strand of research on sustainable recycling of waste thermoplastics in the context of the circular economy. Graphical abstract Image 1 Highlights • Review of the present state of waste plastics and recycling process are presented. • Making bricks out of waste plastics is explored. • Mechanical properties are satisfactory up to 10% of plastic content. • Recycling waste thermoplastics in construction materials is recommended. [ABSTRACT FROM AUTHOR]

Holistically considering the current situation of the commercial synthetic fertilizer (CSF) market, recent global developments, and future projection studies, dependency on CSFs in agricultural production born significant risks, especially to the food security of foreign-dependent countries. The foreign dependency of countries in terms of CSFs can be reduced by the concepts such as the circular economy and resource recovery. Recently, waste streams are considered as a source in order to produce recovery-based fertilizers (RBF). RBFs produced from different waste streams can be substituted with CSFs as input for agricultural applications. Municipal solid waste leachate (MSWL) is one of the waste streams that have a high potential for RBF production. Distribution of the published papers over the years shows that this potential was noticed by more researchers in the millennium. MSWL contains a remarkable amount of nitrogen and phosphorus which are the main nutrients required for agricultural production. These nutrients can be recovered with many different methods such as microalgae cultivation, chemical precipitation, ammonia stripping, membrane separation, etc. MSWL can be generated within the different phases of municipal solid waste (MSW) management. Although it is mainly composed of landfill leachate (LL), composting plant leachate (CPL), incineration plant leachate (IPL), and transfer station leachate (TSL) should be considered as potential sources to produce RBF. This study compiles studies conducted on MSWL from the perspective of nitrogen and phosphorus recovery. Moreover, recent developments and limitations of the subject were extensively discussed and future perspectives were introduced by considering the entire MSW management. Investigated studies in this review showed that the potential of MSWL to produce RBF is significant. The outcomes of this paper will serve the countries for ensuring their food security by implementing the resource recovery concept to produce RBF. Thus, the risks born with the recent global developments could be overcome in this way besides the positive environmental outcomes of resource recovery. • Municipal solid waste leachate should be considered a source of nutrients. • The number of studies based on nutrient recovery from leachate tends to escalate. • Nutrient recovery from leachate contributes to global food security. • The composition of recovery-derived fertilizer should be further investigated. [ABSTRACT FROM AUTHOR]

Current research in Circular Economy (CE) fails to address the occurrence of Rebound Effects (RE), which are systemic and behavioural responses to the implementation of interventions hindering the potential sustainability benefits. This paper aims to advance the academic discussion and the practical consideration of RE by exploring the potential of using System Dynamics (SD) to enable the ex-ante identification of potential RE of CE initiatives. A five-stage simulation-based approach for the identification and mitigation of potential rebound effects (AIMRE) is proposed. Its application is demonstrated in a use-oriented product/service system (PSS) case focused on a high-end dress rental service. The AIMRE enables the representation of the magnitude and reasons for RE occurrence through 14 scenarios. The finding highlights the importance of considering the interplay between consumers' and companies' decision-making processes in quantifying, understanding, and mitigating RE occurrence. • Simulation-based approach to investigate rebound effects (RE). • Helps identify potential RE in Circular Economy (CE) initiatives. • Relies on relevant consumers' and companies' decision-making structures. • Enables quantification through a valid RE magnitude quantification structure. • Scenarios of CE adoption provide insight into the reason for RE occurrence. [ABSTRACT FROM AUTHOR]

This paper studies the effect of Green Public Procurement (GPP) on competition, bids, and winning bids under two different regulation periods where the latter include more explicitly expressed GPP ambitions. Based on detailed data from Swedish internal cleaning service procurements, our results imply that environmental considerations might not influence the bids as required for GPP to be considered an effective environmental policy instrument. Over time, lower degree of competition and increased bids are found. This phenomenon can be attributed, at least in part, to regulatory influences, signifying an escalating complexity in the process of submitting bids. • Contract characteristics other than green demands impact bids and winning bids. • Environmental criteria alone do not influence bids and winning bids. • The number of criteria has a influence on bids and winnings bids. • Findings indicate increased complexity in public procurement bid submission. • In this market, criteria maintain standards rather than driving greener practices. [ABSTRACT FROM AUTHOR]

With the growing population, the accumulation of waste materials (WMs) (industrial/household waste) in the environment incessantly increases, affecting human health. Additionally, it affects the climate and ecosystem of terrestrial and water habitats, thereby needing effective management technology to control environmental pollution. In this aspect, managing these WMs to develop products that mitigate the associated issues is necessary. Researchers continue to focus on WMs management by adopting a circular economy. These WMs convert into useful/value-added products such as polymers and nanomaterials (NMs), especially carbon nanomaterials (CNs). The conversion/transformation of waste material into useful products is one of the best solutions for managing waste. Waste-derived CNs (WD-CNs) have established boundless promises for numerous applications like environmental remediation, energy, catalysts, sensors, and biomedical applications. This review paper discusses the several sources of waste material (agricultural, plastic, industrial, biomass, and other) transforming into WD-CNs, such as carbon nanotubes (CNTs), biochar, graphene, carbon nanofibers (CNFs), carbon dots, etc., are extensively elaborated and their application. The impact of metal doping within the WD-CNs is briefly discussed, along with their applicability to end applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Coastal areas stand out because of their rich biodiversity and high tourist potential due to their privileged geographical position. However, one of the main problems in these areas is the generation of waste and its management, which must consider technical and sustainable criteria. This work aims to conduct a systematic review of the scientific literature on integrated solid waste management (ISWM) by considering scientific publications on the scientific basis for the proposal of sustainability strategies in the context of use and efficiency. The overall method comprises i) Search strategy, merging and processing of the databases (Scopus and Web of Science); ii) Evolution of coastal zone waste management; iii) Systematic reviews on coastal landfills and ISWM in the context of the circular economy; and iv) Quantitative synthesis in integrated waste management. The results show 282 studies focused on coastal landfills and 59 papers on ISWM with the application of circular economy criteria. Systematic reviews allowed for the definition of criteria for the selection of favorable sites, such as i) sites far from the coastline, ii) impermeable soils at their base to avoid contamination of aquifers, iii) use of remote sensing and geographic information system tools for continuous monitoring, iv) mitigation of possible contamination of ecosystems, v) planning the possibility of restoration (reforestation) and protection of the environment. In coastal zones, it is necessary to apply the ISWM approach to avoid landfill flooding and protect the marine environment, reducing rubbish and waste on beaches and oceans. Therefore, applying the circular economy in ISWM is critical to sustainability in coastal environments, with the planet's natural processes and variations due to climate change. [Display omitted] • Waste management is a key challenge for sustainability. • Personal and community education is fundamental to achieving ISWM. • ISWM is linked to the circular economy for sustainability. • Due to climate change, coastal zones must implement ISWM and waste recovery. [ABSTRACT FROM AUTHOR]

The world, a famished planet with an overgrowing population, requires enormous food crops. This scenario compelled the farmers to use a high quantity of synthetic fertilizers for high food crop productivity. However, prolonged usage of chemical fertilizers results in severe adverse effects on soil and water quality. On the other hand, the growing population significantly consumes large quantities of poultry meats. Eventually, this produces a mammoth amount of poultry waste, chicken feathers. Owing to the protein value of the chicken feathers, these wastes are converted into protein hydrolysate and further extend their application as biostimulants for sustained agriculture. The protein profile of chicken feather protein hydrolysate (CFPH) produced through Bacillus spp. was the maximum compared to physical and chemical protein extraction methods. Several studies proved that the application of CFPH and active Bacillus spp. culture to soil and plants results in enhanced plant growth, phytochemical constituents, crop yield, soil nutrients, fertility, microbiome and resistance against diverse abiotic and biotic stresses. Overall, "CFPH - Jack of all trades" and " Bacillus spp. - an active camouflage to the surroundings where they applied showed profound and significant benefits to the plant growth under the most adverse conditions. In addition, Bacillus spp. coheres the biofortification process in plants through the breakdown of metals into metal ions that eventually increase the nutrient value of the food crops. However, detailed information on them is missing. This can be overcome by further real-world studies on rhizoengineering through a multi-omics approach and their interaction with plants. This review has explored the best possible and efficient strategy for managing chicken feather wastes into protein-rich CFPH through Bacillus spp. bioconversion and utilizing the CFPH and Bacillus spp. as biostimulants, biofertilizers, biopesticides and biofortificants. This paper is an excellent report on organic waste management, circular economy and sustainable agriculture research frontier. [Display omitted] • Bacillus spp. mediated bioconversion of chicken feathers into protein hydrolysate. • CFPH, a potent biostimulant for plants and soil microbiome and nutrient enricher. • Bacillus spp., a flagship and paradigm bacteria, act as an effective PGPB and PGPR. • CFPH-and- Bacillus spp., a dynamic duo, enhances plant growth and protects against abiotic and biotic factors. • CFPH-and- Bacillus spp. have multifaceted roles in waste management, sustainable agriculture and circular economy. [ABSTRACT FROM AUTHOR]

An increasing number of countries and regions consider the bioeconomy transition a strategic policy priority. When approached through the lens of a circular economy perspective, investments in bioeconomy have the potential to enhance resource utilisation efficiency, preserve biodiversity and ecosystems, and foster sustainable development with low emissions. At the same time, if requirements and contextual factors of bioeconomy strategies are not formally analysed, bioeconomic investments might lead to unintended negative consequences. This paper proposes a decision support procedure to design, assess, prioritise, and monitor bioeconomy investments and policies. The flexibility and scalability of our decision support procedure is tested in Colombia to foster a regional and local transition to bioeconomy initiatives that consider the local capital assets and the stakeholders' views. The heterogeneous character of the Colombian environment, economy, society and culture represents an ideal condition to test the strength of the decision support procedure to promote bioeconomy in low and middle-income countries. Our empirical results highlight the benefit of adopting a formal assessment framework that includes strategic national indicators, regional features and stakeholders' views. In terms of the Colombian regional bioeconomy ambitions, we highlight the need for expanding knowledge hubs and participatory stakeholder networks and buttressing appropriate financial mechanisms. • Bioeconomy transition needs to be framed in an extended circular economy framework. • Bioeconomy strategies need to consider local context and stakeholders' engagement. • Scalable and replicable decision support procedures should guide bioeconomy implementations. • Balance sheet approach inform all stages of bioeconomy policies and projects. • Application of the balance sheet approach in Colombia highlights diverse local priorities. [ABSTRACT FROM AUTHOR]

The textile industry is a major contributor to global waste, with millions of tons of textiles being discarded annually. Material and energy recovery within circular economy offer sustainable solutions to this problem by extending the life cycle of textiles through repurposing, recycling, and upcycling. These initiatives not only reduce waste but also contribute to the reduction of the demand for virgin materials (i.e. cotton, wool), ultimately benefiting the environment and society. The circular economy approach, which aims to recreate environmental, economic, and societal value, is based on three key principles: waste reduction, material circulation, and ecological restoration. Given these difficulties, circularity incorporates the material recovery approach, which is focused on the conversion of waste into secondary raw resources. The goal of this notion is to extract more value from resources by prolonging final disposal as long as feasible. When a textile has outlived its functional life, material recovery is critical for returning the included materials or energy into the manufacturing cycle. The aim of this paper is to examine the material and energy recovery options of main raw materials used in the fashion industry while highlighting the need of close observation of the relation between circularity and material recovery, including the investigation of barriers to the transition towards a truly circular fashion industry. The final results refer to the main barriers of circular economy transition within the industry and a framework is proposed. These insights are useful for academia, engineers, policy makers and other key stakeholders for the clear understanding of the industry from within and highlight beyond circular economy targets, SDGs interactions with energy and material recovery of textile waste (SDG 7, SDG 11, SDG 12 etc.). [ABSTRACT FROM AUTHOR]

The global production and consumption of plastics, as well as their deposition in the environment, are experiencing exponential growth. In addition, mismanaged plastic waste (PW) losses into drainage channels are a growing source of microplastic (MP) pollution concern. However, the complete understanding of their environmental implications throughout their life cycle is yet to be fully understood. Determining the potential extent to which MPs contribute to overall ecotoxicity is possible through the monitoring of PW release and MP removal during remediation. Life cycle assessments (LCAs) have been extensively utilized in many comparative analyses, such as comparing petroleum-based plastics with biomass and single-use plastics with multi-use alternatives. These assessments typically yield unexpected or paradoxical results. Nevertheless, there is still a paucity of reliable data and tools for conducting LCAs on plastics. On the other hand, the release and impact of MP have so far not been considered in LCA studies. This is due to the absence of inventory-related data regarding MP releases and the characterization factors necessary to quantify the effects of MP. Therefore, this review paper conducts a comprehensive literature review in order to assess the current state of knowledge and data regarding the environmental impacts that occur throughout the life cycle of plastics, along with strategies for plastic management through LCA. • Life cycle assessment (LCA) is a standardized tool designed to aid decision-making. • LCA evaluates the environmental impacts of products throughout their life cycle. • Waste management alternatives for bio-based and conventional plastics are distinct. • Several approaches have been used to mitigate microplastics (MPs). • Existing LCA studies do not address environmental or human health impacts of MPs. [ABSTRACT FROM AUTHOR]

Reverse Logistics (RL) of end-of-use/end-of-life products has become a vital part of circular economy practices for manufacturers. However, significant quantities of resources are still landfilled instead of being recovered. With mounting pressure on businesses to address the sustainability crises (resources, climate change, waste, toxicity) on account of the take-make-dispose-based linear economy, companies today realise the importance of RL but face several barriers to implementing it, including a lack of knowledge. Although several studies have investigated different aspects of RL in various industries in different country settings, less attention has been devoted to developing a systematic and holistic approach for designing and implementing RL. To address these gaps, this paper reviews 116 scholarly articles published between 2011 and 2021 to identify attributes related to the design and implementation of RL systems. Based on a systematic literature review, a conceptual framework is presented covering the key activities, drivers and barriers, stakeholder engagement and performance management in RL. Such a framework can support companies evaluate different approaches and strategies, as well as the opportunities and challenges of designing and implementing RL and transitioning towards a Circular Economy. [Display omitted] • Companies often face challenges in designing & implementing Reverse Logistics (RL). • This paper reviews 116 papers to synthesize the state-of-the-art in RL research. • It covers activities, drivers, barriers, stakeholders, metrics and incentives in RL. • It also investigates industry 4.0 and role of digital technologies in RL systems. • The framework for RL helps businesses plan and implement RL for a circular economy. [ABSTRACT FROM AUTHOR]

How far has the transition process to a circular economy progressed? How can this transition process be promoted? So far, the indicators used to analyse such questions have mostly been based on aggregate recycling rates or waste volumes. However, circular economy is much more than that. This paper develops a concept for empirically measuring the transition process along a company's value chain. The concept distinguishes 27 business activities that are relevant for the circular economy and thus enables detailed statements about the transition to the circular economy along the entire value chain and the three dimensions of the circular economy, i.e. efficiency, closing the resource loop and extending product life. Based on this concept, a representative survey of 8,000 Swiss companies was conducted. The data allow – for the first time and for a representative sample – the analysis of the determinants of the transition process to a circular economy using econometric estimations. The results suggest that the transition process has just started; most companies involved in circular economy activities focus on efficiency enhancing measures rather than on extending the life of products/services or closing the loop. In addition, the results show that circular economy pioneers are characterized by a willingness to invest a significant amount of available capital in the breadth of circular activities, have greater financial flexibility, and in some cases face greater non-price competition. Ultimately, the results suggest that the transition to a circular economy can only be successful if the necessary framework conditions are set in such a way that it is profitable for the company to significantly increase the degree of circularity. • Existing data inadequately reflect the transition to a circular economy at the company level. • This paper presents an initial concept for empirically measuring circular economy activities at the company level. • Based on this concept, a representative survey of 8,000 Swiss companies was conducted. • The results indicate that the transition process has just started. • Economic regressions allow to characterize the pioneers of the circular economy. [ABSTRACT FROM AUTHOR]

With global climate change becoming increasingly serious, carbon neutrality, a key strategy to mitigate climate change, has attracted widespread attention. However, due to the multidisciplinary and complexity of carbon neutrality studies, as well as the diversification of research content, a comprehensive review and systematic synthesis of which is quite limited. In this paper, a bibliometric analysis on the topic of carbon neutrality is conducted to reveal the research progress from a quantitative and visual perspective and describe the evolution of research hotspots. The results show that carbon neutrality research is abundant at both the macro and micro levels. Low carbon development is the premise of carbon neutrality, and emission reduction and carbon sinks are the basis of carbon neutrality. The degree of research varies significantly in different countries, with China dominating in the number of publications, followed by the USA and the UK. The realization of carbon neutrality cannot be fully achieved by one single perspective and requires a comprehensive and systematic analysis of technology, economy, and society. Carbon neutrality is a technology-driven process guided by policy. Economically, carbon taxes and carbon markets are two important market mechanisms for reducing carbon emissions. Technically, researches of negative carbon technologies and renewable energy are growing rapidly. Carbon market, carbon negative technology, circular economy, and green energy will become the focus of future research. This paper helps scholars to understand the overall state of carbon neutrality research and provides a historical reference for future research. • The evolution of carbon neutrality research is identified by a bibliometric method. • Visualizes research status and outlines research foci, frontiers and prospects. • Retrieve 5271 articles published over 25 years in SCIE and SSCI databases. • Carbon neutrality is a technology-driven process guided by policy. • Circular economy and carbon markets are new areas of carbon neutrality research. [ABSTRACT FROM AUTHOR]

The lack of proper management of medical waste leads to environmental pollution and threatens the lives of communities. Good medical waste management means appropriate planning and monitoring at all stages, including collection, separation, treatment, recycling, and disposal which promotes a circular approach. This paper presents a multi-item, multi-period, and bi-objective mixed-integer linear programming circular economy transition model for medical waste management considering the uncertainty in the amount of waste generated to design a green reverse network. In this paper, for the first time, the concept of queuing theory is applied to manage the waiting time of trucks carrying infectious waste in treatment centers. In addition, the proposed model simultaneously addresses the centers' location and heterogeneous vehicles routing, and uses a stochastic scenario-based approach to deal with uncertainty of the waste generated. The purpose of the proposed model is to minimize total cost and population risk, and for this end, to employ an improved augmented epsilon-constraint method (AUGMECON2). Finally, the efficiency of the proposed model and solution approach is examined using the data of a case study in Alborz province that includes six hospitals, three potential collection centers, three potential treatment centers, four potential recycling centers, and three potential disposal centers. • Designing a green reverse logistic network to manage medical waste using an MILP model and the queuing theory. • Using a scenario-based approach to deal with uncertainty in amount of waste generated by hospitals. • Applying AUGMECON2 method for solving the proposed bi-objective MILP model. • Validating the proposed model using the real-world data. [ABSTRACT FROM AUTHOR]

One of the many waste components that end up in landfills is sludge, an organic waste that Black Soldier Flies (BSF) may be capable of reducing or removing along with potential pathogens from the environment. Throughout this review, knowledge gaps were evaluated as well as indications that BSF can positively impact the environment and economy when it comes to reducing sludge. This review first aimed to establish consistency across assessed papers (n = 41). Second, previous research on the efficiency and capability of sludge to be reduced by BSF both in isolation and with other substrates (co-digestion) was assessed. Subsequently, this review also evaluated the resulting safety of both the BSF and remaining sludge after consumption. Through this review, reduction difficulties and gaps in research and industry were evaluated. Unfortunately, complications come from the lack of policy for industry status as well as the need for further research. Therefore, further research is required on the consumption of different sludges. In particular, sludge should be tested with co-substrates to decrease waste removal problems. Sludge lacks crucial nutrients and contains extracellular polymeric substances preventing BSFL consumption. This review could potentially be helpful in future research to formulate a methodology for better BSFL consumption and production of insect biomass by sludge pre-treatment. This could lead to the implementation of the new policy in sludge management. • Black soldier fly larvae can reduce different sludges that may contain pathogens. • There are discrepancies with defining sludge and sludge consumption safety. • Sludge research is primarily focused on fecal sludge, leaving gaps in other sludges. • Sludge consumption by larvae and safety research can aid in waste management policy. [ABSTRACT FROM AUTHOR]

The metal resource crisis and the inherent need for a low-carbon circular economy have driven the rapid development of e-waste recycling technology. High-value waste printed circuit boards (WPCBs) are an essential component of e-waste. However, WPCBs are considered hazardous to the ecosystem due to the presence of heavy metals and brominated organic polymers. Therefore, achieving the recycling of metals in WPCBs is not only a strategic requirement for building a green ecological civilization but also an essential guarantee for achieving a safe supply of mineral resources. This review systematically analyzes the hydrometallurgical technology of metals in WPCBs in recent years. Firstly, the different unit operations of pretreatment in the hydrometallurgical process, which contain disassembly, crushing, and pre-enrichment, were analyzed. Secondly, environmentally friendly hydrometallurgical leaching systems and high-value product regeneration technologies used in recent years to recover metals from WPCBs were evaluated. The leaching techniques, including cyanidation, halide, thiourea, and thiosulfate for precious metals, and inorganic acid, organic acid, and other leaching methods for base metals such as copper and nickel in WPCBs, were outlined, and the leaching performance and greenness of each leaching system were summarized and analyzed. Eventually, based on the advantages of each leaching system and the differences in chemical properties of metals in WPCBs, an integrated and multi-gradient green process for the recovery of WPCBs was proposed, which provides a sustainable pathway for the recovery of metals in WPCBs. This paper provides a reference for realizing the gradient hydrometallurgical recovery of metals from WPCBs to promote the recycling metal resources. • Gentle hydrometallurgy of metals in WPCBs is summarized and analyzed. • Leaching methods for gold, copper and other metals are systematically compared. • A process for clean gradient recovery of multi-metals from WPCBs is proposed. [ABSTRACT FROM AUTHOR]

The circular bio-based economy offers great untapped potential for the food industry as possible valuable products and energy can be recovered from food waste. This can promote more sustainable and resilient food systems in Europe in follow-up of the European Commission's Farm to Fork strategy and support the global transition to more sustainable agri-food systems with the common agricultural and fisheries policies. With its high nutrient content, waste and by-products originating from fish and seafood industry (including aquaculture) are one of the most promising candidates to produce alternative fertilising products which can play a crucial role to replace synthetic mineral fertilisers. Whereas several studies highlighted the opportunities to recover valuable compounds from fishery waste, study towards their potential for the production of fertilising products is still scarce. This study presents an extensive overview of the characteristics of fishery waste and by-products (i.e., fish processing waste, fish sludge, seafood waste/by-products), the state-of-the-art nutrient recovery technologies and recovered nutrients as fertilising products from these waste streams. The European Commission has already adopted a revised Fertilising Products Regulation (EU) 2019/1009 providing opportunities for fertilising products from various bio-based origins. In frame of this opportunity, we address the quality and safety aspects of the fishery waste-derived fertilising products under these criteria and highlight possible obstacles on their way to the market in the future. Considering its high nutrient content and vast abundance, fish sludge has a great potential but should be treated/refined before being applied to soil. In addition to the parameters currently regulated, it is crucial to consider the salinity levels of such fertilising products as well as the possible presence of other micropollutants especially microplastics to warrant their safe use in agriculture. The agronomic performance of fishery waste-derived fertilisers is also compiled and reported in the last section of this review paper, which in most cases perform equally to that of conventional synthetic fertilisers. • Fish processing waste/wastewater/sludge has high protein and lipid contents. • The choice of technology depends on the raw material and desired end-product. • Salinity and microplastics are potential critical parameters. • Fish sludge has a great potential but should be treated/refined before application. • Fishery waste-based fertilisers perform equally to commercial synthetic fertilisers. [ABSTRACT FROM AUTHOR]

The incessant population has increased the production and consumption of plastics, paper, metals, and organic materials, which are discarded as solid waste after their end of life. The accumulation of these wastes has created growing concerns all over the world. However, conventional methods of solid waste management i.e., direct combustion and landfilling have caused several negative impacts on the environment (releasing toxic chemicals and greenhouse gases, huge land use) besides affecting human health. Therefore, it is requisite to determine sustainable alternative technologies that not only help in mitigating environmental issues but also increase the economic value of the discarded solid wastes. This process is known as urban mining where waste is converted into secondary resources and thereby conserves the natural primary resources. Thus, this review highlights the technological advancements in the valorization process of discarded wastes and their sustainable utilization. We also discussed several limitations of the existing urban mining processes and further the feasibility of valorization techniques was critically analyzed from a techno-economical perspective. This paper recommends a novel sustainable model based on the circular economy concept, where waste is urban mined and recovered as a secondary resource to support the united nations sustainable development goals (SDGs). The implementation of this model will ultimately help the developing countries to achieve the target of SDGs 11, 12, and 14. [Display omitted] • The wastes are a reservoir of precious and heavy metals, organics, and plastics. • Urban mining of various types of solid wastes helps in mitigating environmental issues. • A sustainable recovery model for waste to wealth has been recommended. • Implementing a circular economy in solid waste can directly achieve SDGs 11, 12 & 14. [ABSTRACT FROM AUTHOR]

Synthetic antibiotics have been known for years to combat bacterial antibiotics. But their overuse and resistance have become a concern recently. The antibiotics reach the environment, including soil from the manufacturing process and undigested excretion by cattle and humans. It leads to overburden and contamination of the environment. These organic antibiotics remain in the environment for a very long period. During this period, antibiotics come in contact with various flora and fauna. The ill manufacturing practices and inadequate wastewater treatment cause a severe problem to the water bodies. After pretreatment from pharmaceutical industries, the effluents are released to the water bodies such as rivers. Even after pretreatment, effluents contain a significant number of antibiotic residues, which affect the living organisms living in the water bodies. Ultimately, river contaminated water reaches the ocean, spreading the contamination to a vast environment. This review paper discusses the impact of synthetic organic contamination on the environment and its hazardous effect on health. In addition, it analyzes and suggests the biotechnological strategies to tackle organic antibiotic residue proliferation. Moreover, the degradation of organic antibiotic residues by biocatalyst and biochar is analyzed. The circular economy approach for waste-to-resource technology for organic antibiotic residue in China is analyzed for a sustainable solution. Overall, the significant challenges related to synthetic antibiotic residues and future aspects are analyzed in this review paper. • Impact of synthetic organic contamination on the environment and its hazardous effect on health was reviewed. • Biotechnological strategies to tackle organic antibiotic residue proliferation was discussed. • Circular economy approach for waste-to-resource technology in China was analyzed for a sustainable solution. [ABSTRACT FROM AUTHOR]

Due to lower-cost energy supplies elsewhere, Europe needs resource efficient technologies to safeguard the competitiveness of its energy-intensive industries. The technical feasibility of the CCU value chain components (carbon capture, transportation and utilization) has been widely studied in literature. However infrastructural, regulatory and business strategic issues have received less attention. A review of the relevant policies (e.g. European Emissions Trading Scheme, Renewable Fuels and Waste Directives) has been performed. Stakeholder engagement and the stakeholder influence mapping was used to examine potential climate change, circular economy, renewable energy and regional industrial development policies that can support CO 2 utilization value chains. The main contribution of the paper is to outline potential benefits of policies to foster the production and uptake of CO 2 -derived products such as methanol, polyurethane and mineral construction aggregates. Another outcome is to illustrate the role of key policy-making stakeholders in assessing the suitability of current statutes and the impact of potential changes. An important finding was that the development of connectivity infrastructure is a key missing enabler and more attention to policy on infrastructure is required. Finally, the work examines the justification for a CO 2 Utilization Directive, comparable to the Carbon Capture and Storage Directive, but considering the current complexity of the European Union (EU) policy landscape. • Analysis of all European policies relevant to the development of CO2 utilization. • Stakeholder influence analysis for the future development of CCU policy. • Recommendation to consider CO2 as a material for the circular economy. • Stakeholder engagement with industry participants and European institutions. • Rationale for regional burden sharing of risk in developing CCU infrastructure. [ABSTRACT FROM AUTHOR]

Material flow analysis (MFA) is one of the most widely accepted and utilized tools in the industrial-ecology discipline, that measures the input-output materials and examines the pathways and flux of each material flow within the whole system. The application of MFA in e-waste management has recently increased and quite a few academic articles have been published on this issue providing decision support at the policy level. However, there is a need to understand the dynamics of MFA methodology, the data requirements (as well as the data sources used in the previous studies) and the lessons learnt from the studies, so that countries where such an E-waste-MFA study has not yet been performed can apply the international experience of such an emerging research technique. This comprehensive review article presents the recent applications, trends, characteristics, research gaps and challenges of the MFA method that may help e-waste management with an overview of the need for a such tool to be applied. A country-wise analysis is presented and MFA models complemented by various associated methods are summarized with national-level, regional-level, product-level, and element-level assessment. The highlighted future research perspectives discussed in this study will help to analyze e-waste management systems more critically, including the hidden and known flows of waste products and associated materials, economic assessment of material recovery and the role of responsible authorities. This invaluable contribution will help future researchers, particularly from the data collection techniques and previously applied MFA models complemented by various associated methods. • 55 papers on e-waste related material flow analysis (MFA) were analyzed and reviewed. • E-waste generation estimation was the most popular while e-waste characterization was the least research topic. • 20 different research gaps and future research opportunities were highlighted. • Use of state-of-the-art technologies and implementation of software in E-waste-MFA studies are essential. [ABSTRACT FROM AUTHOR]

Boosting the coordination and symbiosis of urbanization and forest ecological security is notably critical for promoting regional green and sustainable development and achieving emission peak and carbon neutrality goals. However, there was still a lack of in-depth analysis of the coupling coordination relationship between urbanization and forest ecological security and its impact mechanism. On the basis of the data from 844 counties in the Yangtze River Economic Belt, this paper explored the spatial differences and influencing factors of the coupling coordination degree of urbanization and forest ecological security. The results manifested that: i) There were apparent spatial disparities in the urbanization index, forest ecological security index, comprehensive index, coupling degree and coupling coordination degree of the Yangtze River Economic Belt. Among them, the spatial pattern of coupling coordination degree had a strong consistency with urbanization index, that is, areas with higher urbanization index also had higher coupling coordination degree. ii) Based on coupling feature identification, it was found that 249 'problem areas' were mainly located in Yunnan Province, southeastern Guizhou Province, central Anhui Province, and central and eastern Jiangsu Province. The main factor for the formation was due to the lag of urbanization in coordinated development. iii) Among the socioeconomic indicators, population structure (0.136), per capita year-end financial institutions loan balance (0.409) and per capita fixed asset investment (0.202) all had a positive impact on coupling coordination degree, while location conditions (−0.126) had a negative impact. Among the natural indicators, soil organic matter (−0.212) and temperature (−0.094) had a negative impact on coupling coordination degree. iv) During the process of coordinated development, it was necessary to increase financial investment and financial support, actively formulate policies to attract talents, enhance the education and publicity of ecological civilization, and develop a green circular economy. The above measures can promote the harmonious development of urbanization and forest ecological security in the Yangtze River Economic Belt. • Exploring the coupling relationship between urbanization and forest eco-security. • Areas with higher urbanization index have higher coupling coordination degree. • Coordinated development is deeply influenced by socioeconomic and natural factors. • Targeted policies for problem areas promote their coordinated development. [ABSTRACT FROM AUTHOR]

Globally, there is increasing interest in recovering resources from sanitation systems. However, the process of planning and implementing circular sanitation is complex and can necessitate software-based tools to support decision-making. In this paper, we review 24 decision support software tools used for sanitation planning, to generate insights into how they address resource recovery across the sanitation chain. The findings reveal that the tools can address many planning issues around resource recovery in sanitation including analysis of material flows, integrating resource recovery technologies and products in the design of sanitation systems, and assessing the sustainability implications of resource recovery. The results and recommendations presented here can guide users in the choice of different tools depending on, for example, what kind of tool features and functions the user is interested in as well as the elements of the planning process and the sanitation service chain that are in focus. However, some issues are not adequately covered and need improvements in the available tools including quantifying the demand for and value of resource recovery products, addressing retrofitting of existing sanitation infrastructure for resource recovery and assessing social impacts of resource recovery from a life cycle perspective. While there is scope to develop new tools or to modify existing ones to cover these gaps, communication efforts are needed to create awareness about existing tools, their functions and how they address resource recovery. It is also important to further integrate the available tools into infrastructure planning and programming processes by e.g. customizing to relevant planning regimes and procedures, to move them beyond research and pilots into practice, and hopefully contribute towards more circular sanitation systems. • We review 24 decision support software tools used for sanitation planning. • We characterize how they address resource recovery aspects. • Several tools analyse material flows and integrate resource recovery technologies and products in sanitation system design. • Many tools have features to assess sustainability aspects of resource recovery. • Recommendations are made for which tools best address each aspect of resource recovery planning. [ABSTRACT FROM AUTHOR]

Process-related carbon emissions, which cannot be completely eliminated by the improvement of processes and energy structure, are recognized as an enormous challenge for in-depth decarbonization. To accelerate the achievement of carbon neutrality, the concept of 'artificial carbon cycle' is proposed based on the integrated system of process-related carbon emissions from high-emitting industries and CCU technology as a potential pathway towards a sustainable future. This paper conducts a systematic review on the integrated system with the case of China, which is the largest carbon-emitting and manufacturing country, to provide a clearer and more meaningful analysis. Multi-index assessment was used to organize the literature and draw the useful conclusion. Based on literature review, the high-quality carbon sources, reasonable carbon capture approaches and promising chemical products were identified and analyzed. Then the potential and practicability of the integrated system was further summarized and analyzed. Finally, key factors of future development including technology improvement, green hydrogen, clean energy and industrial cooperation were stressed to provide a theoretical reference for future researchers and policy makers. • Demonstration on the rationality and importance of applying CCU technology on process-based carbon emissions. • Multi-index assessment on adoptable carbon sources, possible pathways of carbon capture and carbon conversion. • Analysis on the potential and practicability of the integrated system to accelerate carbon neutrality. [ABSTRACT FROM AUTHOR]

Circular Economy Model (CEM) holds the promise to provide an economic benefit while not compromising environmental balance, growth, and competitiveness. The paper presents the proposal of Circular Economy Competitiveness Index (CECI) which measure the development of CEM implementation on country level in areas of social behaviours, business operations, resource management, and innovativeness. CECI combines a catastrophe progression method based on catastrophe theory and principial component analysis into composite index. The paper presents analysis of CECI state and dynamics in EU countries. The model supported with Eurostat data allow to classify the EU countries into four groups based on CEMI dynamic as well as analyse EU traditional regions' competitiveness in context of CE implementation. Additionally, correlation to Global Competitiveness Index (GCI) has been analysed. The paper presents a quantitative reference for evaluating CE competitiveness and offers relevant implications for EU countries' policymakers in relation to the factors determining that competitiveness. • The paper explores impact of Circular Economy implementation on countries' competitiveness. • Circular Economy Competitiveness Index (CECI) based on catastrophe progression method is proposed. • UK, Italy, Sweden, Netherlands are leading EU countries according to CECI, because they balanced energy and material consumption. • CECI can be useful indicator for government to stimulate economy transformation while not losing competitiveness. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoate (PHA) is a type of polyesters produced in the form of accumulated intracellular granules by many microorganisms. It is viewed as an environmentally friendly bioproduct due to its biodegradability and biocompatibility. The production of the PHA using oil substrates such as waste oil and plant oil, has gained considerable attention due to the high product yield and lower substrate cost. Nevertheless, the PHA fermentation using oil substrate is complicated due to the heterogenous fatty acid composition, varied bio-accessibility and possible inhibitory effect on the bacterial culture. This review presents the current state-of-the-art of PHA production from oil-based substrates. This paper firstly discusses the technical details, such as the choice of bacteria strain and fermentation conditions, characteristic of the oil substrate as well as the PHA composition and application. Finally, the paper discusses the challenges and prospects for up-scaling towards a cleaner and effective bioprocess. From the literature review, depending on the cell culture and the type of PHA produced, the oil platform can have a PHA yield of 0.2–0.8 g PHA/g oil substrate, with PHA content mostly from 40 to 90% of the cell dry weight. There is an on-going search for more effective oil-utilising PHA producers and lower cost substrate for effective PHA production. The final application of the PHA polymer influences the treatment needed during downstream processing and its economic performance. PHA with different compositions exhibits varied decomposition behaviour under different conditions, requiring further insight towards its management towards a sustainable circular economy. [Display omitted] • The review focuses on the use of lipid waste for polyhydroxyalkanoate (PHA) production. • The PHA yield with lipid substrate is around 0.4–0.6 g PHA/g oil substrate. • The effect of fatty acids composition on the polymer makeup requires more insight. • Strategies were identified to improve the economic performance of PHA fermentation. • The decomposition behaviours differ among polymers and under different environments. [ABSTRACT FROM AUTHOR]

Abstract Remediation of polluted soils using phytoremediation techniques is an effective strategy. However, the use of the biomass from these soils for energy purposes may raise efficiency and pollution emission problems and there is currently little research on this issue. In this work, the main results of a fluidized-bed gasification treatment conducted on poplar biomass pruning residues from a multi-contaminated area are presented. The samples were collected from an experimental site in which a plant-assisted bioremediation (PABR) technology has been applied since 2013 to reduce the soil heavy metal (HM) and polychlorinated biphenyl (PCB) contents. The main goal of this study was to identify the specific treatment necessary, in addition to conventional tar reforming, for trapping possible residues of HMs and PCBs in ashes during the gasification process. In our study, we demonstrate that gasification of contaminated biomass coming from PABR (where contaminant residues are concentrated mainly in the roots and are insignificant in the shoots) produces syngas whose characteristics are similar to those obtained using non-contaminated biomass. The results showed that contaminant concentrations in the prunings were negligible; the total amount of PCBs was 1.63 ng/g, while HMs ranged from 0.01 to 0.70 mg/kg, except for Cu and Zn (∼20 mg/kg). Furthermore, the presence in the biomass of Ca and traces of other metals showed a possible catalytic effect with an improvement in the tar conversion in the gasifier leading to a reduction of 5–10% in tar content. The overall results suggest that a specific treatment for pollutant capture is necessary only when the roots, the part of the plants where these contaminants are concentrated, are sampled and used for the gasification process. Although energy from biomass produced on a contaminated site is currently considered waste and involves disposal costs, this paper shows that the poplar biomass grown on a multi-contaminated soil can be used for energy purposes without any impact on the environment. Graphical abstract Image 1 Highlights • Biomass quality assessment is necessary for evaluating gasification capabilities. • Poplar from PABR accumulate contaminants mainly in the roots. • Trace PCB concentrations in biomass not affect the gasification treatment. • The soil characteristics affect the yield and quality of syngas. • Ca occurrence in soil and biomass has a catalytic effect in tar cracking increase. [ABSTRACT FROM AUTHOR]

Abstract The introduction of effective solid waste management strategies in developing countries should be considered for improving sustainability at global level. Many barriers should be overcome, concerning the introduction of environmental policies, effective investments, social inclusion and public awareness, which are significant issues in low-middle income countries. The Circular Economy could represent the answer for improving current solid waste management activities worldwide, since denote the principle of waste valorization and recycling for boosting developing economies. This paper is focused on this theme, analyzing main opportunities for improving the current state of solid waste management in developing big cities. The solid waste management of two countries are reviewed: Romania is the emerging country where Circular Economy is becoming a future objective due to economic aids and strength regulations which the European Union (EU) established for the nations forming parts the alliance; as a comparison, Bolivia is reported for evaluating main differences founded for developing recycling systems in a no-EU country. These two case studies could be of interest for highlighting main pros and cons of the participation into a wide organization like the EU for introducing in short terms Circular Economy principles. Moreover, a theoretical Circular Economy model for developing big cities in low-middle income countries is described within the study for effectively comparing which chances can spread for these countries as regard municipal solid waste exploitation. Despite the economic level, Romania and Bolivia are both facing with many solid waste management issues although in different magnitude. For the Romanian case study, it is visible how it cannot achieve the European goals for 2020 due the need of change in public recycling behavior. Bolivia, instead, represents the case where international aids and new investments are required, considering the informal sector into the formal management system as a real opportunity for improving local recycling rate. In conclusion, the comparison suggests how external supports led to implement the principles of the Circular Economy within a developing region. The model of Circular Economy proposed is recommended for developing big cities in order to advance a new form of safe employment, encouraging the activities that are still in action (i.e. informal sector) and boosting the principles of sustainable development. Highlights • A circular economy model for developing countries was presented. • Solid waste management of Romania and Bolivia can be compared. • Municipal and "special" solid waste should be managed in an integrated manner. • Integrated regulations about solid waste are essential for developing countries. • The informal sector plays a key role on sustainable solid waste management. [ABSTRACT FROM AUTHOR]

Abstract This study presents a methodology that allows the analysis of how an existing product design meets the design guidelines required from the circular economy perspective, and which are the design guidelines that would need to be incorporated into its design to become a better circular design product. For that, as a starting point, the design guidelines required for the circular product design have been identified from an extensive literature review. Then, criteria have been defined to measure the margin of improvement of a product design based on the level of compliance of each circular design guideline, and the relevance of each circular design guideline for the specific product category to which it belongs. Finally, the methodology has been applied to a representative sample of 127 appliances belonging to different categories of small household electrical and electronic equipment. The circular design guidelines related to extending life span and to product/components reuse have been identified as those that more urgently need to be incorporated, while the urgency of those related to connectors or product structure is moderate. Graphical abstract Image Highlights • This research reviews design guidelines from the perspective of circular economy. • A methodology is proposed for evaluating the level of circularity of products. • The paper introduces a case study on 127 small electrical and electronic equipment. [ABSTRACT FROM AUTHOR]

The paper provides a systematic literature review to investigate whether circular economy (CE) performance in the technical cycle will contribute to the sustainable development. Two academic databases, namely Scopus and Web of Science were used to retrieve research papers which span over the period 2000–2019. The research articles were classified according to the Sustainable Development Goals (SDG's) addressed, industries involved, key areas of CE, pillars of sustainability, CE principles (R-Imperatives and Systems perspective), type of cycle in CE, and transversality (generic, product-specific and sector-specific). The review highlights various research gaps concerning the proposed classification. The research gaps will provide new emerging areas to the CE and will help to align the CE performance with the SDGs. • Indicators can evaluate the Circular Economy (CE) performance of studies. • CE performance can lead to sustainable development. • Major contribution of CE performance is to SDG12, SDG7, SDG9, SDG6, SDG8 and SDG11. [ABSTRACT FROM AUTHOR]

Resource depletion and environmental pollution are increasingly a matter of concern for their adverse effects on ecosystems, human health, and the economy. Circular Economy (CE) practices can help us address these challenges. This paper proposes a composite circularity index (CI) to assess the level of implementation of CE practices. The main advantage of the proposed index is its ability to combine multiple indicators of circularity for different units operating in a given sector (given as inputs), using a 'Benefit of the Doubt' model. This new model is innovative in the manner it deals with ordinal scales and also by considering both relative and absolute performance indices. These indices are computed using mathematical programming tools, building on ideas from Data Envelopment Analysis models. Although the model can be applied to any sector, this work addresses the hotel industry in particular. The selection of indicators for this CI was based on seven blocks of the Circular Economy Action Plan and a literature review of circular practices. An application of the proposed index is performed by using data from Portuguese and Spanish hotels. The proposed CI allows the identification of the organizations with the best and worst performance in implementing the CE practices and clarifying the benchmarks they could follow to improve their level of circularity. Moreover, the index analysis also provides specific targets for improvement, indicating which circular practices should be improved for the lower performers to reach the implementation levels of the best performers. • A circularity index based on DEA and the Circular Economy Action Plan is developed. • The circularity index is customized and applied to 51 hotels in Portugal and Spain. • Targets and priorities aimed at reducing hotels' footprint are discussed. • The method proposed offers potential for application in many other sectors. • 19 hotels are efficient, and the average efficiency is 85.26% in a relative assessment. [ABSTRACT FROM AUTHOR]

Olive mill wastewater sludge (OMWS) is a by-product of the olive extraction process that is attracting substantial attention due to its extremely hazardous effects on aquatic and terrestrial ecosystems. OMWS is a product of the common disposal method of olive oil mill wastewater (OMWW) that accumulates in evaporation ponds. It is estimated that approximately 10 × 106 m3 of OMWS is generated worldwide each year. OMWS is characterized by its significantly variable physicochemical properties and organic pollutant constituents, such as phenols and lipids, which are dependent upon the environmental features of the receiving ponds. Nonetheless, many related studies have recognized the biofertilizer potential of this sludge owing to its high mineral nutrient and organic matter load. OMWS exhibits promising valorization potential in several fields, including agriculture and energy production. Compared to those of OMWW, studies of OMWS are still lacking concerning its composition and characteristics, which are necessary for the future implementation of efficient valorization strategies. The main purpose of this review paper is to fill the gap that exists in the literature by providing a critical analysis of the available data on OMWS production, distribution, characteristics, and properties. Additionally, this work sheds light on important factors affecting OMWS properties, including the variability of the indigenous microbial communities regarding bioremediation. Finally, this review addresses the current and future valorization routes, from detoxification to the development of promising applications in agriculture, energy, and the environment, which could have significant socioeconomic implications for low-income Mediterranean countries. [Display omitted] • Olive mill wastewater sludge is characterized by a very high pollutant load. • Olive mill wastewater sludge secondary treatment negatively impacts the indigenous microflora. • Composting is the most suitable process for olive mill wastewater sludge treatment. • The nutritional content of olive mill wastewater sludge has great potential in agriculture. [ABSTRACT FROM AUTHOR]

In recent years, circular business models (CBM) have become an inevitable requirement to foster improvements in environmental performance. However, the current literature rarely discusses the link between Internet of Things (IoT) and CBM. This paper first identifies four IoT capabilities including monitoring, tracking, optimization and design evolution for improving CBM performance based on the ReSOLVE framework. In a second step, a systematic literature review using the PRISMA approach analyzes how these capabilities contribute to 6 R and CBM through the CBM-6R and CBM-IoT cross-section heatmaps and relationship frameworks, followed by assessing the quantitative impacts of IoT on potential energy saving in CBM. Finally, challenges are analyzed for the realization of IoT-enabled CBM. The results show that the assessments of Loop and Optimize business models dominate current studies. IoT plays a significant role in these business models respectively through tracking, monitoring and optimization capabilities. While (quantitative) case studies for Virtualize , Exchange and Regenerate CBM are substantially needed. IoT holds the potential to reduce energy consumption by around 20–30% for referenced applications in the literature. However, the IoT hardware, software and protocol energy consumption, interoperability, security and financial investment might become main obstacles for the wider use of IoT in CBM. • A mapping framework is built connecting ReSOLVE with 4 IoT capabilities and 6Rs. • IoT-enabled tracking and monitoring capabilities dominates Loop model. • Optimize model is related to 'Reduce' by monitoring and optimization of IoT. • IoT provides virtual and dematerialized solutions, supporting 'Redesign' strategy. • IoT reduces the energy use of the Optimize and Loop business model with 20–30%. [ABSTRACT FROM AUTHOR]

There is a general conception that environmental firms are more adapted to green solutions, and environmental patents are just lagging. The existing literature has paid particular attention to identifying obstacles and situational factors associated with established firms going green and has concentrated on how and why established businesses are becoming more financially viable and ecologically sustainable. In changing environment, manufacturing companies are direct contributors to environmental impacts. Increased awareness of consumers about the environment puts a handful amount of pressure on manufacturing companies to care about the environment. It also asserts unseen pressure on the financial performance of the companies. Therefore, it is time to go for green patenting of such firms while satisfying the eco-innovation and environmental scanning process. Moreover, Environmental ownership and its associated parameters keenly monitor this aspect. This paper evaluates the performance of the support vector machine (SVM/SVR) approach for estimating patents in environment-related technologies (PERT) in China from 1995 to 2021. For this work, six independent variables related to environmental ownership and environment-related technologies were selected, which include medium and high-tech exports (MHTE), green patents applicants (GPA), listed domestic companies (LDC), human capital index (HCI), self-employment (SE), and manufacturing value added in GDP (MVA). Data for dependent and independent variables were gathered from the World Bank (WB) official data bank portal. To make an initial understanding of the data basic statistical summary was computed in R programming to see the mean, minimum and maximum values in the data set. A correlation matrix plot showed the association between dependent and independent variables. SVM/SVR with radial basis function (RBF) regression was applied to see the impact of contributing parameters that influence PERT. For PERT, the model generated 0.95 R2 (RMSE = 92.43). The results of the SVR showed that the association among environmental parameters is strong. With a value of 4.82, the strongest coefficient in the SVR model is PAR. This work is novel and will benefit the manufacturing sector, analysts, policymakers, environmentalists as how green patenting can boost the eco innovation and environmental ownership and scanning system with advance technologies and practices. • Exploring the connection between environment parameters and the green patents in manufacturing technologies utilized in SDGs. • Application of support vector machine (SVM/SVR) approach for estimating patents in environment-related technologies (PERT). • Green patents applications and environmental ownership has positive association with the SDGs and Circular economy boosters. [ABSTRACT FROM AUTHOR]

Wastewater management is included in one of the 17 Sustainable Development Goals (SDGs): SDG 6 is dedicated to water and sanitation and sets out to “ensure availability and sustainable management of water and sanitation for all”. SDG 6 expands the Millennium Development Goals (MDGs) focus on drinking water and basic sanitation to now cover the entire water cycle, including the management of water, wastewater and ecosystem resources. A UN report in 2017 states that likely over 80% of the wastewater worldwide is still discharged without adequate treatment. In several countries the wastewater management is nowadays a norm, but still there are open discussions about the kind of approach to be adopted, i.e. centralisation vs. decentralisation. The choice of the adopted technologies is strictly linked to environmental performances and economical aspects; one of the possible causes for the still enormous amount of untreated wastewater discharged into the environment can be the low “willingness to pay” for this kind of service and therefore a great focus should be given to all the technologies that are able to lower the treatment costs still maintaining reliable and robust performances in the long term. When considering wastewater as a carrier of valuable primary chemicals that can be easily converted to marketable products (fertilisers, bio-plastics, soil conditioners, biofuels, etc.), and as well as a relevant source of “new water” to be used for specific purposes, wastewater and runoff management can be highlighted as one of the most exciting challenges and occasions for a sustainable development in the near future. The paper aims to clarify the future role of CWs in circular economy, resource-oriented, and ecosystem services approaches, which want to respond to sanitation worldwide and the future research needs. We give an overview on how the conventional wastewater treatment scheme (what we call “waste paradigm”) should move towards more sustainable water and biogeochemical cycles following the new resource-oriented, circular economy and ecosystem service views. On this basis, we review the potential application of CWs within this new, and needed, paradigm. Finally, a meta-analysis shows that the scientific community involved in CWs should put more effort in making CWs more suitable for these new tasks. [ABSTRACT FROM AUTHOR]

This paper assesses the economic viability of the production process of an innovative form of digestate known as "microfiltered digestate", suitable for use as a fertilizer in driplines for permanent crops. A Break-Even Analysis was performed to determine the Break-Even Point which identifies the minimum quantity of products necessary to cover production costs at a certain selling price. Our results show that the production of microfiltered digestate provides positive economic viability for anaerobic digestion managers, providing them with an attractive market outlet and, at the same time, a new form of income. The experimental study was stated in Sicily, but it is replicable in any territorial context with anaerobic digestion plants. The results are in line with the principles of circular economy and are very current with reference to the use of organic fertilizers instead of chemical ones. • Innovative micro-filtered digestate (MFD) is a new source of income. • A stategy to decrease the degree of dependence on public subsidies. • Break-Even Analysis was made to determine lower convenient level of production. • Break-Even Point was estimated for three different selling price. • MFD guarantee high economic profitability for the companies that produce it. [ABSTRACT FROM AUTHOR]

Implementation of green roofs requires a large amount of primary material, especially for constructing the growing media layer. In addition, irrigation of green roofs with potable water is uneconomical and unsustainable. The novel hybrid green roof system proposed in this paper is in line with the principles of circular economy as it incorporates recycled materials into green roof growing media and greywater for irrigation. Two experimental beds were built to evaluate the concept of treating greywater in a constructed wetland prior to using it to irrigate a dual-layer extensive green roof. The growing media in both two extensive green roof beds contained ca. 37.5% by volume of recycled crushed building rubble containing a large proportion of brick. One of the two beds additionally contained 9.5% by volume of sewage sludge-based biochar. The concept of the hybrid roof and novel growing media was evaluated based on laboratory analysis of the growing media and on onsite measurements of hydraulic and thermal performance. The growing media amended with recycled materials developed in this study had hydrophysical properties comparable to commercially available growing media without recycled materials. Observations made during one vegetation season from June to October and a ten day-intensive water quality monitoring campaign during September 2020 showed that the constructed wetland significantly reduced total nitrogen and orthophosphate concentrations in pre-treated greywater. Due to the irrigation method employed, in which water flowed predominantly through drainage mats below the growing media, nutrient-leaching by the irrigation water was avoided. Concentrations of nutrients in the effluent were observed to increase only in response to precipitation. The temperature peak of the bottom green roof layer was shifted by almost 9 h from the peak in air temperature, and temperature fluctuations were significantly reduced. Vegetation on the bed amended with biochar demonstrated more vigorous growth due to available nutrients in the biochar which increased the rate of temperature-reducing evapotranspiration. More water evapotranspirated more water, which provided more water retention capacity confirmed by a lower runoff coefficient. Simple storage routing hydraulic modeling of hybrid green roof runoff using a nonlinear reservoir was performed. [Display omitted] • Hybrid constructed wetland - green roof concept was developed. • Performance of the concept was successfully tested on experimental beds. • Biochar and recycled crushed brick were used in newly developed growing media. • Ability of CW to reduce nutrient concentration was confirmed. • Runoff was successfully simulated by non-linear reservoir model. [ABSTRACT FROM AUTHOR]

With the ongoing urbanization in developing regions, integrating regional waste disposal capability is challenging due to unbalanced economic development and rising environmental issues. This research proposed a multi-dimensional symbiotic integration of waste disposal capability. Applying data from the Yangtze River Delta (YRD) in China, we first explore the waste flows and interactions between cities to identify the possibility of inter-municipal collaboration based on the augmented gravity model. We then employ social network analysis to categorize the cities in the collaborative network of waste disposal into subgroups by functionalities. Finally, we proposed the top-down framework of symbiotic networks for waste disposal. Our findings indicate that YRD cities can be classified into four types according to their waste density and disposal efficiency: High-High, Low-High, Low-Low, and High-Low. We also identify three types of inter-municipal collaborative relationships: between high-density and high-efficiency cities, between high-density cities, and between high-efficiency cities. The city subgroups can be categorized into "high-efficiency clusters," "high-density clusters," and "hub clusters," which pave the way for a shared or complementary urban symbiosis in the waste recycling industry. The division of roles among subgroups enables symbiotic activities within the city cluster. This paper extends the spatial scope of industrial symbiosis literature and has practical implications for transitioning to a circular economy in waste management of developing countries. [Display omitted] • Inter-municipal collaboration based on spatial heterogeneity is discussed. • DEA model, the gravity model, and social network analysis is employed. • Complementary or shared symbiotic cooperation between cities is emerging. • Cities are clustered into different functional subgroups. • We proposed a symbiotic waste disposal network. [ABSTRACT FROM AUTHOR]

Sustainable development and circular economy rules force the global fertilizer industry to develop new phosphorous recovery methods from alternative sources. In this paper a phosphorus recovery technology from Polish industrial Sewage Sludge Ashes was investigated (PolFerAsh – Polish Fertilizers form Ash). A wet method with the use of mineral acid and neutralization was proposed. Detailed characteristic of SSA from largest mono-combustion plans were given and compared to raw materials used on the market. The technological factors associated with such materials were discussed. The composition of the extracts was compared to typical industrial phosphoric acid and standard values characterizing suspension fertilizers. The most favorable conditions for selective precipitation of phosphorus compounds were revealed. The fertilizers obtained also meet EU regulations in the case of the newly discussed Cd content. The process was scaled up and a flow mass diagram was defined. [ABSTRACT FROM AUTHOR]