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  Subjects -> CONSERVATION (Total: 128 journals)
Showing 1 - 37 of 37 Journals sorted alphabetically
Advanced Sustainable Systems     Hybrid Journal   (Followers: 6)
African Journal of Ecology     Hybrid Journal   (Followers: 17)
African Journal of Range & Forage Science     Hybrid Journal   (Followers: 12)
African Journal of Wildlife Research     Full-text available via subscription   (Followers: 6)
AICCM Bulletin     Hybrid Journal   (Followers: 3)
Ambiens. Revista Iberoamericana Universitaria en Ambiente, Sociedad y Sustentabilidad     Open Access  
American Journal of Rural Development     Open Access   (Followers: 5)
Animal Conservation     Hybrid Journal   (Followers: 48)
Aquaculture, Aquarium, Conservation & Legislation - International Journal of the Bioflux Society     Open Access   (Followers: 9)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 44)
Arcada : Revista de conservación del patrimonio cultural     Open Access  
Archeomatica     Open Access   (Followers: 4)
Arid Land Research and Management     Hybrid Journal   (Followers: 10)
Asian Journal of Sustainability and Social Responsibility     Open Access   (Followers: 2)
Australasian Plant Conservation: Journal of the Australian Network for Plant Conservation     Full-text available via subscription   (Followers: 4)
Biodiversity and Conservation     Open Access   (Followers: 192)
Biological Conservation     Hybrid Journal   (Followers: 242)
Bulletin of the American Museum of Natural History     Open Access   (Followers: 9)
Business Strategy and the Environment     Hybrid Journal   (Followers: 10)
Challenges in Sustainability     Open Access   (Followers: 10)
Conservación Vegetal     Open Access   (Followers: 1)
Conservation     Hybrid Journal   (Followers: 28)
Conservation Biology     Hybrid Journal   (Followers: 272)
Conservation Genetics     Hybrid Journal   (Followers: 23)
Conservation Science     Open Access   (Followers: 28)
Conservation Science and Practice     Open Access   (Followers: 1)
Diversity and Distributions     Open Access   (Followers: 42)
Earth's Future     Open Access   (Followers: 6)
Eastern European Countryside     Open Access   (Followers: 2)
Ecological Economics     Hybrid Journal   (Followers: 133)
Ecological Psychology     Hybrid Journal   (Followers: 3)
Ecological Restoration     Full-text available via subscription   (Followers: 22)
Ecology and Evolution     Open Access   (Followers: 96)
Ecology and Society     Open Access   (Followers: 51)
Environment and Planning E : Nature and Space     Hybrid Journal   (Followers: 5)
Environment Conservation Journal     Open Access   (Followers: 6)
Environmental and Resource Economics     Hybrid Journal   (Followers: 28)
Environmental and Sustainability Indicators     Open Access   (Followers: 6)
Environmental Conservation     Hybrid Journal   (Followers: 63)
Ethnobiology and Conservation     Open Access   (Followers: 3)
European Countryside     Open Access   (Followers: 1)
Forest Policy and Economics     Hybrid Journal   (Followers: 21)
Forum Journal     Full-text available via subscription   (Followers: 1)
Frontiers in Ecology and Evolution     Open Access   (Followers: 45)
Functional Ecology     Hybrid Journal   (Followers: 47)
Future Anterior     Full-text available via subscription  
Global Ecology and Biogeography     Hybrid Journal   (Followers: 65)
Global Ecology and Conservation     Open Access   (Followers: 13)
Human Dimensions of Wildlife: An International Journal     Hybrid Journal   (Followers: 6)
Ideas in Ecology and Evolution     Open Access   (Followers: 9)
In Situ. Revue des patrimoines     Open Access  
Indonesian Journal of Conservation     Open Access  
Indonesian Journal of Sustainability Accounting and Management     Open Access  
Interações (Campo Grande)     Open Access  
Interdisciplinary Environmental Review     Hybrid Journal   (Followers: 3)
International Journal of Architectural Heritage: Conservation, Analysis, and Restoration     Hybrid Journal   (Followers: 6)
International Journal of Biodiversity Science and Management     Open Access   (Followers: 6)
International Journal of Environment and Pollution     Hybrid Journal   (Followers: 3)
International Journal of Global Energy Issues     Hybrid Journal   (Followers: 8)
International Journal of Social Ecology and Sustainable Development     Full-text available via subscription   (Followers: 4)
International Journal of Sustainable Development     Hybrid Journal   (Followers: 17)
International Journal of Sustainable Development and World Ecology     Hybrid Journal   (Followers: 8)
International Soil and Water Conservation Research     Open Access   (Followers: 2)
Intervención     Open Access  
Journal for Nature Conservation     Hybrid Journal   (Followers: 27)
Journal for the Study of Religion, Nature and Culture     Hybrid Journal   (Followers: 12)
Journal of Cultural Heritage Management and Sustainable Development     Hybrid Journal   (Followers: 8)
Journal of East African Natural History     Full-text available via subscription   (Followers: 7)
Journal of Ecology and The Natural Environment     Open Access   (Followers: 5)
Journal of Industrial Ecology     Hybrid Journal   (Followers: 17)
Journal of International Wildlife Law & Policy     Hybrid Journal   (Followers: 5)
Journal of Natural Resources Policy Research     Hybrid Journal   (Followers: 10)
Journal of Paper Conservation     Hybrid Journal   (Followers: 2)
Journal of Rural Studies     Hybrid Journal   (Followers: 18)
Journal of Sustainable Mining     Open Access   (Followers: 3)
Journal of the American Institute for Conservation     Hybrid Journal   (Followers: 4)
Journal of the Institute of Conservation     Hybrid Journal   (Followers: 25)
Journal of Threatened Taxa     Open Access   (Followers: 1)
Journal of Urban Ecology     Open Access   (Followers: 6)
Julius-Kühn-Archiv     Open Access  
Lakes & Reservoirs Research & Management     Hybrid Journal   (Followers: 14)
Landscape and Urban Planning     Hybrid Journal   (Followers: 35)
Madagascar Conservation & Development     Open Access   (Followers: 2)
Madera y Bosques     Open Access  
Natural Resources and Conservation     Open Access   (Followers: 6)
Natural Resources Forum     Hybrid Journal   (Followers: 7)
Nature Conservation     Open Access   (Followers: 35)
Nature Sustainability     Hybrid Journal   (Followers: 14)
Neotropical Biology and Conservation     Open Access   (Followers: 2)
Nepalese Journal of Development and Rural Studies     Open Access  
Novos Cadernos NAEA     Open Access  
npj Urban Sustainability     Open Access  
Nusantara Bioscience     Open Access  
One Ecosystem     Open Access  
Oryx     Open Access   (Followers: 20)
Pacific Conservation Biology     Full-text available via subscription   (Followers: 2)
Park Watch     Full-text available via subscription   (Followers: 1)
Process Integration and Optimization for Sustainability     Hybrid Journal  
Rangeland Journal     Hybrid Journal   (Followers: 1)
Recursos Rurais     Open Access  
Recycling     Open Access  
Regional Sustainability     Open Access  
Resources, Conservation & Recycling     Hybrid Journal   (Followers: 20)
Resources, Conservation & Recycling : X     Open Access   (Followers: 1)
Restoration Ecology     Hybrid Journal   (Followers: 46)
Revista de Ciencias Ambientales     Open Access  
Revista de Direito e Sustentabilidade     Open Access  
Revista Meio Ambiente e Sustentabilidade     Open Access  
Revista Memorare     Open Access  
Rural Sustainability Research     Open Access   (Followers: 2)
Savana Cendana     Open Access  
Society & Natural Resources: An International Journal     Hybrid Journal   (Followers: 21)
Socio-Ecological Practice Research     Hybrid Journal  
Soil Ecology Letters     Hybrid Journal  
Southern Forests : a Journal of Forest Science     Hybrid Journal   (Followers: 3)
Studies in Conservation     Hybrid Journal   (Followers: 16)
Sustainable Earth     Open Access   (Followers: 2)
Sustainable Environment Agricultural Science (SEAS)     Open Access  
Tanzania Journal of Forestry and Nature Conservation     Full-text available via subscription   (Followers: 2)
Tropical Conservation Science     Open Access   (Followers: 1)
Tropical Ecology     Hybrid Journal  
VITRUVIO : International Journal of Architectural Technology and Sustainability     Open Access  
Water Conservation Science and Engineering     Hybrid Journal  
Wildfowl     Open Access   (Followers: 11)
Wildlife Australia     Full-text available via subscription   (Followers: 1)
Wildlife Research     Hybrid Journal   (Followers: 18)
World Review of Entrepreneurship, Management and Sustainable Development     Hybrid Journal   (Followers: 1)

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  This is an Open Access Journal Open Access journal
ISSN (Online) 2313-4321
Published by MDPI Homepage  [84 journals]
  • Recycling, Vol. 7, Pages 42: Understanding Business Requirements for
           Increasing the Uptake of Recycled Plastic: A Value Chain Perspective

    • Authors: Malou van der Vegt, Evert-Jan Velzing, Martijn Rietbergen, Rhiannon Hunt
      First page: 42
      Abstract: Circularity and recycling are gaining increased attention, yet the amount of recycled plastic applied in new products remains low. To accelerate its uptake by businesses, it will be useful to empirically investigate the barriers, enablers, needs and, ultimately, requirements to increase uptake of recycled plastic feedstock for the production of new plastic products. During the six focus group sessions we conducted, a value chain approach was used to map the factors that actors face regarding the implementation of recycled materials. The identified factors were structured based on three levels: determining whether a certain factor acted as a barrier or enabler, identifying the steps in the value chain that the factor directly affected and the category it could be subdivided into. The results were then further processed by translating the (rather abstract) needs of businesses into (specific) requirements from industry. This study presented eight business requirements that require actions from other actors in the value chain: design for recycling, optimised waste processing, standardisation, material knowledge, showing possibilities, information and education, cooperation, and regulation and government intervention. The main scientific contributions were the value chain perspective and the applied relevance of the findings. Future studies may delve deeper into the individual factors identified.
      Citation: Recycling
      PubDate: 2022-06-29
      DOI: 10.3390/recycling7040042
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 43: Environmental and Economic Comparison of
           Natural and Recycled Aggregates Using LCA

    • Authors: Adriana Dias, Salem Nezami, José Silvestre, Rawaz Kurda, Rui Silva, Isabel Martins, Jorge de Brito
      First page: 43
      Abstract: Recycled aggregates (RAs) have been playing an important role in replacing natural aggregates (NAs) in concrete production, thereby contributing to a reduction in the extraction of natural resources and the promotion of a circular economy. However, it is important to assess the global impacts of this replacement, in both environmental and economic terms. In this study, an overview of the impacts of the production of natural and recycled aggregates is presented, using the life cycle assessment (LCA) methodology. Through this methodology, products with the same function are compared and information about the best solutions is given, considering their environmental and economic impacts. Studies with data collected from specific producers were compared, as well as environmental product declarations (EPDs) and generic databases, regarding the production of natural and recycled, coarse and fine, and rolled and crushed aggregates. This study intends therefore to provide the environmental and economic impact comparison at the global level through LCA from different data sources. According to this literature review, the best and worst environmental results are assigned to lower and higher transport distances, respectively. Regarding EPDs, the lowest environmental impacts are related to recycled coarse aggregates and the highest to natural coarse crushed aggregates. In terms of generic databases, the results are similar, with the lowest impacts associated with natural fine rolled aggregates and the highest to natural coarse crushed aggregates. In what concerns the economic impacts, in general, recycled aggregates are associated with the lowest costs. However, these results are highly dependent on transport distances and costs.
      Citation: Recycling
      PubDate: 2022-06-30
      DOI: 10.3390/recycling7040043
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 44: Improving the Separation of PS and ABS
           Plastics Using Modified Induced Air Flotation with a Mixing Device

    • Authors: Pattarasiri Fagkaew, Nattawin Chawaloesphonsiya, Saret Bun, Pisut Painmanakul
      First page: 44
      Abstract: A dramatic increase in plastic waste has resulted in a strong need to increase plastic recycling accordingly. A selective flotation has been highlighted due to its outstanding efficiency for the separation of mixed plastics with analogous physicochemical characteristics. In this study, the effects of design and operational factors on the bubble’s hydrodynamic and mixing parameters in induced air flotation (IAF) with a mixing device were investigated through a design of experiment method (DOE) analysis for improving the plastic separation efficiency (i.e., PS and ABS). As a result of DOE analysis, the increase in the induced air tube diameter together with the rotational speed could generate a smaller bubble size. This led to the enhancement of the ratio of interfacial area to velocity gradient (a/G), which was interestingly found to be a significant factor affecting plastic recovery apart from the chemical agents. It demonstrates that operating IAF with a mixing device at a greater a/G ratio improved the plastic separation performance. These findings suggest that operating an IAF process with a mixing device at suitable a/G conditions could be a promising technique for separating plastic wastes, which have similar physicochemical characteristics as PS and ABS.
      Citation: Recycling
      PubDate: 2022-07-04
      DOI: 10.3390/recycling7040044
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 45: Recycling of Lead Pastes from Spent

    • Authors: Yongliang Xiong
      First page: 45
      Abstract: Lead–acid batteries are important to modern society because of their wide usage and low cost. The primary source for production of new lead–acid batteries is from recycling spent lead–acid batteries. In spent lead–acid batteries, lead is primarily present as lead pastes. In lead pastes, the dominant component is lead sulfate (PbSO4, mineral name anglesite) and lead oxide sulfate (PbO•PbSO4, mineral name lanarkite), which accounts for more than 60% of lead pastes. In the recycling process for lead–acid batteries, the desulphurization of lead sulfate is the key part to the overall process. In this work, the thermodynamic constraints for desulphurization via the hydrometallurgical route for recycling lead pastes are presented. The thermodynamic constraints are established according to the thermodynamic model that is applicable and important to recycling of lead pastes via hydrometallurgical routes in high ionic strength solutions that are expected to be in industrial processes. The thermodynamic database is based on the Pitzer equations for calculations of activity coefficients of aqueous species. The desulphurization of lead sulfates represented by PbSO4 can be achieved through the following routes. (1) conversion to lead oxalate in oxalate-bearing solutions; (2) conversion to lead monoxide in alkaline solutions; and (3) conversion to lead carbonate in carbonate solutions. Among the above three routes, the conversion to lead oxalate is environmentally friendly and has a strong thermodynamic driving force. Oxalate-bearing solutions such as oxalic acid and potassium oxalate solutions will provide high activities of oxalate that are many orders of magnitude higher than those required for conversion of anglesite or lanarkite to lead oxalate, in accordance with the thermodynamic model established for the oxalate system. An additional advantage of the oxalate conversion route is that no additional reductant is needed to reduce lead dioxide to lead oxide or lead sulfate, as there is a strong thermodynamic force to convert lead dioxide directly to lead oxalate. As lanarkite is an important sulfate-bearing phase in lead pastes, this study evaluates the solubility constant for lanarkite regarding the following reaction, based on the solubility data, PbO•PbSO4 + 2H+ ⇌ 2Pb2+ + SO42− + H2O(l).
      Citation: Recycling
      PubDate: 2022-07-12
      DOI: 10.3390/recycling7040045
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 46: Leading the World: A Review of Household
           Recycling in Wales

    • Authors: Ian D. Williams, Joseph Phillips
      First page: 46
      Abstract: Wales is one of the world leaders in household waste recycling with a steady recent recycling rate of ~65%. The Welsh Assembly Government (WAG) set a statutory target of achieving a 70% recycling rate by 2024/25. We reviewed historical trends in waste management in Wales from 2006 to 2020, with a focus on recycling. Authoritative, official data were obtained from WasteDataFlow, an Internet system for municipal waste data reporting by UK local authorities to government. Data are collected quarterly allowing the generation of time series plots, trendlines and like-for-like comparisons between groupings of various characteristics, such as number of separate kerbside collections, income, political preference, and impact of policy changes. Results showed that the approach taken by the WAG to politically prioritise and encourage participation in household recycling has achieved impressive results that contrast starkly with the recycling performance of other UK countries. In Wales, household waste disposed annually per person via landfill decreased from ~410 kg to <50 kg and household waste recycled increased from to ~150 kg to ~310 kg, with a recent increase in incineration with energy recovery to ~135 kg as infrastructure has come online. Recycling rates show a seasonal variation due to increases in garden waste sent for composting in the summer. There are variations in local authority performance across Wales, mainly caused by variations in the number of separate collections. Co-mingled collections tend to lead to higher contamination of recyclates that are then not able to be sold for recycling. Deprivation, as indicated by differences in income, also influences total waste arisings and recycling rates. A plateau of ~65% recycling rate was reached in 2020, with incineration reaching a rate of >25%. The recycling rate plateaus at exactly the same time as incineration comes on stream. Evidence demonstrates that improvements to recycling rates can become more difficult when incineration becomes available. Whilst further reductions and improvements to recycling in Wales will be more challenging, the WAG’s track record of focused proactive political and policy support shows what can be achieved when there is suitable political will. The WAG has demonstrated that it tends to deliver on its waste-related plans, and it clearly has the best chance of any of the UK’s four countries of achieving its aims.
      Citation: Recycling
      PubDate: 2022-07-18
      DOI: 10.3390/recycling7040046
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 47: Skid Resistance Performance of Asphalt
           Mixtures Containing Recycled Pavement Materials under Simulated Weather

    • Authors: Maria Pomoni, Christina Plati
      First page: 47
      Abstract: One of the challenges of using recycled materials in road structures is to maintain safe and durable pavements. A multitude of research has been conducted over the years on various recycled materials, with a focus on the structural performance of pavements. Another crucial, but almost overlooked, aspect is the pavement’s ability to provide adequate skid resistance for road users under different climatic conditions. With this in mind, the present study aimed to investigate the skid resistance of asphalt mixtures containing two different types of recycled materials under laboratory-simulated weather conditions. Conventional hot-mix asphalt (HMA) and mixtures containing either reclaimed asphalt pavement (RAP) for aggregate replacement or crumb rubber (CR) as a bitumen additive were prepared and tested at different temperatures and different surface conditions (i.e., dry/wet) following a wetting protocol. Skid resistance was measured using a British Pendulum Tester (BPT). The results showed that the recycled mixtures performed similarly to conventional ones in terms of the skid resistance when the temperature was varied and under variable simulated surface conditions too. In some cases, they performed even better than conventional mixtures. Overall, a promising potential is demonstrated towards the use of the investigated recycled materials in asphalt surface courses.
      Citation: Recycling
      PubDate: 2022-07-19
      DOI: 10.3390/recycling7040047
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 48: An Approach for Automated Disassembly of
           Lithium-Ion Battery Packs and High-Quality Recycling Using Computer
           Vision, Labeling, and Material Characterization

    • Authors: Merle Zorn, Christina Ionescu, Domenic Klohs, Konstantin Zähl, Niklas Kisseler, Alexandra Daldrup, Sigrid Hams, Yun Zheng, Christian Offermanns, Sabine Flamme, Christoph Henke, Achim Kampker, Bernd Friedrich
      First page: 48
      Abstract: A large number of battery pack returns from electric vehicles (EV) is expected for the next years, which requires economically efficient disassembly capacities. This cannot be met through purely manual processing and, therefore, needs to be automated. The variance of different battery pack designs in terms of (non-) solvable fitting technology and superstructures complicate this. In order to realize an automated disassembly, a computer vision pipeline is proposed. The approach of instance segmentation and point cloud registration is applied and validated within a demonstrator grasping busbars from the battery pack. To improve the sorting of the battery pack components to achieve high-quality recycling after the disassembly, a labeling system containing the relevant data (e.g., cathode chemistry) about the battery pack is proposed. In addition, the use of sensor-based sorting technologies for peripheral components of the battery pack is evaluated. For this purpose, components such as battery pack and module housings of multiple manufacturers were investigated for their variation in material composition. At the current stage, these components are usually produced as composites, so that, for a high-quality recycling, a pre-treatment may be necessary.
      Citation: Recycling
      PubDate: 2022-07-20
      DOI: 10.3390/recycling7040048
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 49: Stakeholder Assessment on Closing Nutrient
           Cycles through Co-Recycling of Biodegradable Household Kitchen Waste and
           Black Water between Rural and Urban Areas in South India

    • Authors: Veronika Fendel, Martin Kranert, Claudia Maurer, Gabriela Garcés-Sánchez, Jingjing Huang, Girija Ramakrishna
      First page: 49
      Abstract: Agricultural land degradation, urban migration, increasing food demand and waste, and inadequate sanitation systems all affect farmers, local society, and the environment in South India. Joint recycling of biodegradable secondary household resources to close nutrient cycles between urban and rural regions can address all these challenges and thus several SDGs at the same time. Efforts are being made to this end, but many attempts fail. The central research question is, therefore: how can co-recycling concepts be evaluated in this context' For this purpose, composting plants, biogas fermenters, and a high-tech concept to produce plant charcoal, design fertilizer, and biopolymers are considered. The aim of this study is to evaluate the recycling concepts from the stakeholders’ perspective to avoid gaps between theory and practice. Six expert and one focus group interviews on two successful on-site case studies and 15 online expert interviews with thematic actors were qualitatively evaluated and presented in a social network analysis to identify preferences and indicators for the further evaluation of co-recycling concepts. The results show that the focus is on mature technologies such as compost and biogas. High-tech solutions are currently still in rudimentary demand but will play a more important role in the future. To evaluate such concepts, seven key indicators and their measured values were identified and clustered into the categories ecological, social, technical, economic, and connective. The results show that this methodology of close interaction with stakeholders and the evaluation of successful regional case studies minimize the gap between practice and theory, contribute to several goals of the SDGs, and thus enable such concepts to be implemented sustainably.
      Citation: Recycling
      PubDate: 2022-07-20
      DOI: 10.3390/recycling7040049
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 50: Use of a Design of Experiments (DOE) for
           Studying the Substitution of Natural River Sand (NRS) by Gold Mine
           Tailings (GMT) in Concrete Manufacturing

    • Authors: Clarisse Njovu Balegamire, Pierre Jean-Marie Dable, Kouwelton Kone, Bossissi Nkuba
      First page: 50
      Abstract: The extraction of precious minerals leaves behind an important amount of tailings. When stored in nature, these tailings contribute to environmental degradation. To reduce this degradation, tailings are incorporated in construction as substitute to natural materials. The objective of this study was to use a design of experiments (DOE) to reveal how the substitution of natural river sand (NRS) by gold mine tailings (GMT) in concrete manufacturing can be optimally achieved. This DOE considered three constituents: the amounts of NRS/GMT, that of gravel and of cement. The experimental domain was defined within the concrete standards dosage of 350 kg/m3 and 400 kg/m3 as the lower and upper levels, respectively. The smallest compressive strength on standard cubic specimens on the 28th day varied between 11 N/mm2 and 37 N/mm2 following to the experimental domain. The values of the compressive strength of the experiments carried out allowed to acquire the model of the strength with the coefficients of each factor: Strength=23.25−5.86*A+4.56*B−1.96*C−0.56*A*B+1.41*A*C+1.08*B*C+0.71*A*B*C (with A: GMT+NRS; B: cement; C: gravel). The values of the cumulative weight of the coefficients of each factor were 36.7% (A), 64.5% (B) and 76.6% (C). The study also found that a larger dosage of gravel (40 kg) improves the concrete compressive strength when GMT substitutes NRS between 70% and 100% and when 15 kg of cement is used. For a sustainable and better reuse of GMT as construction materials, an economic and environmental study (the leaching of metals) of the concrete based on GMT would be ideal to consider a large scale production.
      Citation: Recycling
      PubDate: 2022-07-26
      DOI: 10.3390/recycling7040050
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 51: A State-of-the-Art Review on the
           Incorporation of Recycled Concrete Aggregates in Geopolymer Concrete

    • Authors: Bahareh Nikmehr, Riyadh Al-Ameri
      First page: 51
      Abstract: Geopolymer concrete (GC) has the potential to incorporate recycled concrete aggregates (RCA) obtained from construction and demolition waste. This research aims to review the current state-of-the-art knowledge of the RCA in GC and identify the existing knowledge gaps for future research direction. This paper highlights the essential factors that impact the GC’s mechanical and durability properties. Moreover, the influence of various percentages of coarse and fine RCA and the pattern of their replacement will be assessed. The effect of aluminosilicate material, alkaline activators, and curing regime also will be evaluated. Besides, the durability-related characteristics of this concrete will be analysed. The impact of exposure to a higher temperature, freeze–thaw cycles, marine environment, and acid and alkali attack will be comprehensively reviewed. A literature review revealed that increasing alumina silicate content, such as slag and metakaolin, and increasing the Na2SiO3/NaOH ratio and alkali-activator-to-binder ratio improve the hardened GC. However, increasing slag and metakaolin content and the Na2SiO3/NaOH ratio has an adverse impact on its workability. Therefore, finding the optimum mix design for using RCA in GC is vital. Moreover, there is a scope for developing a self-compacting GC cured at ambient temperature using RCA.
      Citation: Recycling
      PubDate: 2022-07-27
      DOI: 10.3390/recycling7040051
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 52: Factors Influencing Household Waste
           Separation Behavior: Cases of Russia and Finland

    • Authors: Anna Zaikova, Ivan Deviatkin, Jouni Havukainen, Mika Horttanainen, Thomas Fruergaard Astrup, Minna Saunila, Ari Happonen
      First page: 52
      Abstract: This paper investigates the factors influencing the behavior of individuals in source-separation of municipal solid waste in an immature system for collection of recyclable waste (Saint Petersburg, Russia) and a more mature waste system (selected urban areas, Finland). Online questionnaires were applied to collect data from citizens of Saint Petersburg and the Finnish urban population. The data were examined within an extended theory of planned behavior using structural equation modeling for the identification of factors affecting waste source-separation behavior. The findings indicate that the factors differed significantly in the two waste systems. In Russia, the inconvenience of waste collection limited waste source-separation behavior, while intentions of individuals and information availability had an almost equal positive effect. In Finland, waste source-separation behavior was mostly affected by people’s intentions. Based on the findings, recommendations for the development of recycling practices were made for practitioners in Russia and possibly other early-stage systems for the collection of recyclable waste. Limitations of the study pinpointed the possibilities for future research.
      Citation: Recycling
      PubDate: 2022-07-28
      DOI: 10.3390/recycling7040052
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 53: Unpicking the Gender Gap: Examining
           Socio-Demographic Factors and Repair Resources in Clothing Repair Practice

    • Authors: Rachel H. McQueen, Lisa S. McNeill, Qinglan Huang, Balkrushna Potdar
      First page: 53
      Abstract: Increased fashion consumption spurred by fast fashion has led to excessive textile waste, giving rise to a global crisis as textile waste pollutes land and waterways, while landfill and incineration contribute to global greenhouse gas emissions. Extending a product’s life for as long as possible is a core principle of the circular economy (CE) to ensure that the maximum value of the original product is realized over its lifetime. As such, repair is an essential component of a CE because it supports the preferred waste hierarchy elements of reduce and reuse, with recycling being the last resort in a CE necessary to close resource loops. Consumers are an essential enabler of a CE; therefore, it is critical to understand consumers’ characteristics in the context of behaviors such as repair. The purpose of this study was to examine the role of gender on engagement in clothing repair practices; women have often only been the focus of clothing repair studies. An online survey was conducted to collect responses from Canadian and U.S. consumers (n = 512). Findings showed that self-repair was the most common form of clothing repair, with women being more highly engaged in self-repair practices, increasing with age. Paid repair is the type of repair that has the lowest level of engagement, and there are only negligible differences between the genders. Men utilize unpaid forms of repair more than women. However, among the youngest age group (18–24), both genders are equally likely to have clothing repaired for free. Gender gaps exist, but opportunities for increased utilization in repair can be created to encourage full participation within a CE. In particular, the findings point to the importance of increasing repair activities amongst men and younger consumers.
      Citation: Recycling
      PubDate: 2022-08-05
      DOI: 10.3390/recycling7040053
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 54: Agro-Industrial Wastewater Treatment with

    • Authors: Nuno Jorge, Ana R. Teixeira, Marco S. Lucas, José A. Peres
      First page: 54
      Abstract: The removal of dissolved organic carbon (DOC) and total polyphenols (TPh) from agro-industrial wastewater was evaluated via the application of coagulation–flocculation–decantation (CFD) and Fenton-based processes. For the CFD process, an organic coagulant based on Acacia dealbata Link. leaf powder (LP) was applied. The results showed that the application of the LP at pH 3.0, with an LP:DOC ratio of 0.5:1 (w/w), achieved a high removal of turbidity, total suspended solids (TSS), and volatile suspended solids (VSS) of 84.7, 79.1, and 76.6%, respectively. The CFD sludge was recycled as fertilizer in plant culture (germination index ≥ 80%). Afterwards, the direct application of Fenton-based processes to raw WW was assessed. The Fenton-based processes (UV/Fenton, UV/Fenton-like, and heterogeneous UV/Fenton) showed high energy efficiency and a cost of 1.29, 1.31 and 1.82 €/g/L DOC removal, respectively. The combination of both processes showed the near complete removal of TPh and DOC after 240 min of reaction time, with high energy efficiency. In accordance with the results obtained, the combination of CFD with Fenton-based processes achieves the legal limits for the disposal of water into the environment, thus allowing the water to be recycled for irrigation.
      Citation: Recycling
      PubDate: 2022-08-08
      DOI: 10.3390/recycling7040054
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 55: Experimental and Artificial Neural
           Network-Based Study on the Sorptivity Characteristics of Geopolymer
           Concrete with Recycled Cementitious Materials and Basalt Fibres

    • Authors: Sherin Khadeeja Rahman, Riyadh Al-Ameri
      First page: 55
      Abstract: The environmental concerns regarding the production of the most widely consumed cement construction material have led to the need for developing sustainable alternatives. Using recycled industry waste products such as fly ash and slag via geopolymerisation has led to the development of geopolymer cement—an efficient replacement for ordinary Portland cement (OPC). Adopting geopolymer cement and concrete as a construction material reduces greenhouse gas and promotes the recycling of waste products. This study explores the suitability of a unique geopolymer concrete mix made of recycled cementitious materials including industry waste products such as fly ash, micro fly ash and slag for use in aggressive environments. Sorptivity tests are conducted to assess the durability of concrete and indicate the cementitious material’s ability to transmit water through the capillary forces. This study thus reports on the sorptivity characteristics of a newly developed self-compacting geopolymer concrete and two other fibre geopolymer concrete mixes containing 1% (by weight) of 12 mm- or 30 mm-long basalt fibres. The addition of basalt fibres indicated less water absorption and moisture ingress than the mix without fibres. The study used 18 specimens from three geopolymer concrete mixes, and the results showed that adding fibres improved the durability performance in terms of resistance to moisture ingress. Finally, an artificial neural network model is developed to predict the absorption rates of geopolymer concrete specimens using MATLAB. The prediction models reported excellent agreement between experimental and simulated datasets.
      Citation: Recycling
      PubDate: 2022-08-09
      DOI: 10.3390/recycling7040055
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 56: Special Issue “Feature Papers in
           Recycling 2021”

    • Authors: Francesco Paolo La Mantia, Beatrice Castellani
      First page: 56
      Abstract: Recycling is the collection and conversion process of waste materials into second raw materials [...]
      Citation: Recycling
      PubDate: 2022-08-11
      DOI: 10.3390/recycling7040056
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 57: Reclaiming the Value of Cotton Waste
           Textiles: A New Improved Method to Recycle Cotton Waste Textiles via Acid

    • Authors: Edvin Ruuth, Miguel Sanchis-Sebastiá, Per Tomas Larsson, Anita Teleman, Amparo Jiménez-Quero, Sara Delestig, Viktor Sahlberg, Patricia Salén, Marjorie Sanchez Ortiz, Simran Vadher, Ola Wallberg
      First page: 57
      Abstract: The fashion industry is becoming one of the largest emitters worldwide due to its high consumption of raw materials, its effluents, and the fact that every garment will eventually contribute to the vast amount of waste being incinerated or accumulating in landfills. Although fiber-to-fiber recycling processes are being developed, the mechanical properties of the textile fibers are typically degraded with each such recycle. Thus, tertiary recycling alternatives where textiles are depolymerized to convert them into valuable products are needed to provide end-of-life alternatives and to achieve circularity in the fashion industry. We have developed a method whereby cotton waste textiles are depolymerized to form a glucose solution, using sulfuric acid as the sole catalyst, with a high yield (>70%). The glucose solution produced in this process has a high concentration (>100 g/L), which reduces the purification cost and makes the process industrially relevant. This method can be applied regardless of the quality of the fibers and could therefore process other cellulosic fibers such as viscose. The glucose produced could subsequently be fermented into butanediol or caprolactam, precursors for the production of synthetic textile fibers, thus retaining the value of the waste textiles within the textile value chain.
      Citation: Recycling
      PubDate: 2022-08-12
      DOI: 10.3390/recycling7040057
      Issue No: Vol. 7, No. 4 (2022)
  • Recycling, Vol. 7, Pages 26: Liberation and Separation of Valuable
           Components from LED Modules: Presentation of Two Innovative Approaches

    • Authors: Adam Balinski, Volker Recksiek, Michael Stoll, Christian Christesen, Michael Stelter
      First page: 26
      Abstract: The rapid development of light-emitting-diode (LED) technology is attributed to its superiority over light sources of earlier generations. Although LED lamps, compared to compact fluorescent lamps, are considered less harmful to the environment, there is still no efficient solution to deal with them at the end of their lifecycle. The first part of the study provides a detailed characterisation of LED lamps, focusing on their most interesting component: the LED module. LED packages attached to the module are highly enriched with Ga, In, Pd, Ag, Au, Sr, Y, Ce, Eu, Gd, and Lu, with the content of each element varying greatly depending on the LED technology. In the second part of this research, two new approaches for liberation and concentration of valuable components from LED modules are presented and compared: a chemical route and a thermal route. The chemical treatment leads to a highly selective separation of LED chips and encapsulation. Enrichment factors up to about 125 are achieved, and a concentrate is obtained containing approximately 14 wt% of the aforementioned valuable components. However, the process requires aromatic solvents, which are viewed as toxic. The thermal treatment results in separation of the aluminium heat sink from all other components of the LED module. Enrichment is approximately ten times lower, but the approach is technically feasible.
      Citation: Recycling
      PubDate: 2022-04-19
      DOI: 10.3390/recycling7030026
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 27: Treatment of Scrap Tire for Rubber and Carbon
           Black Recovery

    • Authors: Alaa Sultan Abdulrahman, Fawzi Habeeb Jabrail
      First page: 27
      Abstract: In this study, a chemical dissolution treatment was used to recover rubber and carbon black (CB) from truck tire scrap, with gas oil acting as the solvent and 4-Hydroxy-TEMPO acting as the catalyst for the chemical reactions. Montmorillonite clay was used to separate the rubber solution from the CB and the other non-dissolved tire additives. The recovered rubber and CB were characterized together with the original scrap tire sample by XRD, SEM, BET and thermal analysis, as well as FTIR and 1H NMR spectral analyses. Characterization of the chemical structure of the recovered rubber showed that the main functional groups of styrene−butadiene rubber blend with natural rubber. The thermal behavior and crystalline structure of the recovered rubber, as well as its morphological images, showed that the properties of the rubber sample were acceptable and similar to natural rubber. The recovered CB characterizations showed that the sample after pyrolysis was a highly crystalline nanocomposite structure with a high specific surface area and scattered pores.
      Citation: Recycling
      PubDate: 2022-04-20
      DOI: 10.3390/recycling7030027
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 28: The Physical Characterization and Terminal
           Velocities of Aluminium, Iron and Plastic Bottle Caps in a Water

    • Authors: Alexander A. Nikolaev
      First page: 28
      Abstract: Aluminium, iron and plastic are materials which are extensively used at both industry and individual levels. However, significant amounts of aluminium, iron and plastic end up in the environment. Specifically, bottle caps made of these materials are often thrown away, with or without bottles, and appear among the common plastic debris entering the world’s oceans and beaches. More than 20 million bottle caps and lids have been identified during beach-cleaning campaigns over the last 30 years. To recover bottle caps from the shores, conventional technologies can be used. In this paper, the physical properties of used metal and plastic bottle caps were examined and related to the settling and rising velocities of the caps, as well as their drag coefficients and hydrodynamic modes in water environments, with respect to gravity separation. The sample contained aluminium, iron, high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP) bottle caps. The findings revealed that the density differences between the bottle caps resulted in the terminal settling velocities of aluminium and iron particles, which were significantly higher than the rising velocities of the plastic caps. The results allowed us to design a flowsheet for bottle cap recovery from beach coasts in order to reduce environmental impact and produce add-on plastic and metal products.
      Citation: Recycling
      PubDate: 2022-04-22
      DOI: 10.3390/recycling7030028
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 29: Analysis of Plastic-Derived Fuel Oil Produced
           from High- and Low-Density Polyethylene

    • Authors: Chandni Joshi Jangid, Kevin M. Miller, Jeffrey R. Seay
      First page: 29
      Abstract: The exponential growth of waste plastic accumulation has had an irreversible and lasting impact on the world. An imminent threat to marine and terrestrial ecosystems of massive proportions, plastic waste accumulation is a global problem that will not only have to be tackled by current generations but for many generations to follow. The scale of current recycling technologies and efforts to reduce consumption by for-profit and non-profit institutions, governments, and consumers will need to be rapidly increased to combat the negative impacts plastic waste has had on the planet since its conception. This is especially the case in areas with limited infrastructure to properly collect, manage, and dispose of plastic waste. Solutions to plastic waste accumulation crisis that are appropriate for the developing world are urgently needed. Conversion of plastic waste to liquid fuel by slow pyrolysis is a technology that is particularly suitable for developing countries due to its ability to convert polyolefin waste plastic into a useful product, thus preventing its eventual accumulation in the ecosystem. However, in developing countries, conversion techniques that do not rely on sophisticated technologies are needed. Since processing time and operating temperature are the simplest variables to control, an analytical study has been conducted to assess how the molecular composition of plastic derived fuel oil (PDFO) is impacted by these parameters. The results of gas chromatography-mass spectrometry (GC-MS) and thermogravimetric analysis (TGA) studies of PDFO from high- and low-density polyethylene plastic waste produced using appropriate technology techniques are presented alongside a comparison with traditional diesel fuel and kerosene. This approach is novel in that it differs from previously conducted research, which has studied the use of catalysts, additives, or single operating temperatures to assess the composition of PDFO. Therefore, this research contribution presents a simplistic and inexpensive approach for tuning PDFO composition in appropriate technology settings.
      Citation: Recycling
      PubDate: 2022-05-07
      DOI: 10.3390/recycling7030029
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 30: Processing of Gypsum Construction and
           Demolition Waste and Properties of Secondary Gypsum Binder

    • Authors: Girts Bumanis, Jelizaveta Zorica, Aleksandrs Korjakins, Diana Bajare
      First page: 30
      Abstract: The waste amount coming from construction and demolition (CDW) has significant volume and potential to provide the backbone of a secondary material bank. Up to now, little attention is paid to waste gypsum recycling from CDW while a shift in global attitude toward waste management brings motivation to use CDW gypsum as secondary raw material. The present research investigates the properties of gypsum binder obtained from secondary raw materials originating from CDW. Three types of drywall boards and cast monolithic gypsum from interior walls, treated in the laboratory, and a gypsum binder was obtained. Comparison has been studied and the most effective solutions regarding CDW treatment are represented. Separation, crushing, and milling were done. DTA/TG, XRD, SEM, and particle size distribution were characterized by CDW gypsum. The heat treatment temperature was selected at 130 °C for 4 or 24 h and 180 °C for 4 h. Consistency, set time, and mechanical properties were characterized. Results indicate that a gypsum binder with a strength up to 3.7 MPa can be obtained. Low strength is associated with fineness of CDW gypsum and a high water/gypsum ratio (from 0.6 to 1.396). Gypsum content in CDW (38 to 92 wt.%) should be considered as an important factor during gypsum CDW recycling.
      Citation: Recycling
      PubDate: 2022-05-17
      DOI: 10.3390/recycling7030030
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 31: Zero Liquid Discharge System for the Tannery
           Industry—An Overview of Sustainable Approaches

    • Authors: Rajamanickam Ricky, Subramanian Shanthakumar, Ganapathy Pattukandan Ganapathy, Fulvia Chiampo
      First page: 31
      Abstract: The tannery industry is characterized by the consumption of a large quantity of water, around 30–40 m3 for processing 1000 kg of hide or skin. This amount becomes wastewater, containing about 300 kg of different chemicals, mainly refractory organic compounds, with high chemical oxygen demand (COD), total dissolved salts (TDS), chromium, and evolution of toxic gases, such as ammonia and sulfides, etc. The remaining tanning chemicals are released as effluent having high resistance against biological degradation, becoming a serious environmental issue. Usually, end-of-pipe treatment is not sufficient to meet the concerns of environmental issues. In terms of cleaner production options, the redesigning of the existing effluent treatment procedures with alternate or additional treatment techniques, which “supports resource recovery with no added chemicals”, is expected to give a sustainable solution for the management of toxic effluent. The Zero Liquid Discharge (ZLD) system serves to ensure zero water emission, as well as treatment facilities by recycling, recovery, and reuse of the treated wastewater using advanced cleanup technology. The international scenario shows the implementation of ZLD thanks to pressure from regulatory agencies. The ZLD system consists of a pre-treatment system with conventional physicochemical treatment, tertiary treatment, softening of the treated effluent, reverse osmosis (RO) treatment for desalination, and thermal evaporation of the saline reject from RO to separate the salts. By adopting this system, water consumption is reduced. Moreover, ZLD also becomes effective in disaster mitigation in areas where the tannery industry is a strong economic actor. With this review, we aim to give an outlook of the current framework.
      Citation: Recycling
      PubDate: 2022-05-24
      DOI: 10.3390/recycling7030031
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 32: Identifying Future Skill Requirements of the
           Job Profiles for a Sustainable European Manufacturing Industry 4.0

    • Authors: Tugce Akyazi, Patricia del Val, Aitor Goti, Aitor Oyarbide
      First page: 32
      Abstract: The exponential growth of digitalisation and the continuous increase in sustainability needs are currently reshaping the European manufacturing industry through its entire value chain. Industrial sectors have undergone significant changes globally in recent years, and they will continue to face this deep transformation. The manufacturing sectors, more specifically, companies, need to develop a relevant strategy that can support their organisation to handle the upcoming future technological developments and sustainability requirements properly. In order to implement the strategy effectively and achieve an adequate digital and green transformation, their main focus should be the development of a multi-skilled workforce. This competent workforce can only be built by foreseeing the changes in the needed skills for the manufacturing industry and then updating the skills of the current workforce accordingly. As an answer to this need, we developed an automated skill database for the manufacturing industry, particularly transversal occupations of this sector related to the industrial symbiosis (IS) and energy efficiency (EE). Differently from the conventional ones, the generated database incorporated not only the current but also the future skill needs for each profile. During the development of the future skills for each occupation in the database, we identified the foreseen skill needs for the manufacturing industry through detailed desk research. Therefore, this paper presents a valuable perspective on the subject. Our work aimed to fill the gap for a database specifically developed for the manufacturing industry, which provides the end-users with data about the new skills requirements resulting from industrial changes and sustainability needs. We believe that companies, education and training institutions and policymakers can make use of the generated database as a complementary tool for developing their training programmes or strategy roadmaps to cover the emerging changes in each individual industrial sector.
      Citation: Recycling
      PubDate: 2022-05-26
      DOI: 10.3390/recycling7030032
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 33: Lithium-Ion Battery Recycling in the Circular
           Economy: A Review

    • Authors: Md Tasbirul Islam, Usha Iyer-Raniga
      First page: 33
      Abstract: Lithium-ion batteries have become a crucial part of the energy supply chain for transportation (in electric vehicles) and renewable energy storage systems. Recycling is considered one of the most effective ways for recovering the materials for spent LIB streams and circulating the material in the critical supply chain. However, few review articles have been published in the research domain of recycling and the circular economy, with most mainly focusing on either recycling methods or the challenges and opportunities in the circular economy for spent LIBs. This paper reviewed 93 articles (66 original research articles and 27 review articles) identified in the Web of Science core collection database. The study showed that publications in the area are increasing exponentially, with many focusing on recycling and recovery-related issues; policy and regulatory affairs received less attention than recycling. Most of the studies were experiments followed by evaluation and planning (as per the categorization made). Pre-treatment processes were widely discussed, which is a critical part of hydrometallurgy and direct physical recycling (DPR). DPR is a promising recycling technique that requires further attention. Some of the issues that require further consideration include a techno-economic assessment of the recycling process, safe reverse logistics, a global EV assessment revealing material recovery potential, and a lifecycle assessment of experiments processes (both in the hydrometallurgical and pyrometallurgical processes). Furthermore, the application of the circular business model and associated stakeholders’ engagement, clear and definitive policy guidelines, extended producer responsibility implications, and material tracking, and identification deserve further focus. This study presents several future research directions that would be useful for academics and policymakers taking necessary steps such as product design, integrated recycling techniques, intra-industry stakeholder cooperation, business model development, techno-economic analysis, and others towards achieving a circular economy in the LIB value chain.
      Citation: Recycling
      PubDate: 2022-05-28
      DOI: 10.3390/recycling7030033
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 34: A Study of the Feasibility of Using Grey
           Sedge Residue to Facilitate Zero Waste Production

    • Authors: Kamonwan Chucheep, Nathaporn Suwanpayak, Naree Phanchindawan
      First page: 34
      Abstract: There is approximately 30% of grey sedge (Lepironia articulata) residue remaining from weaving production that could add value to support zero waste management. Therefore, the aim of this research was to study the feasibility of using a residue of grey sedge or Krajood strips from weaving production to form a value-added product. To obtain preliminary data, Krajood strip residue was examined for its biological and physical properties. In addition, the biological and physical properties of Krajood strip residue in combination with loam soil (KSRL) were examined and compared with the properties of loam soil (LS) itself. The results showed that the total microbe and moisture content of the Krajood strip residue was significantly higher than that of the products made from Krajood strips (KS). The stress value of Krajood strips was higher than the stress values of other samples except for that of a bag made of paper. Identification of bacteria and mold by MALDI Biotyper and DNA sequencing compared with BLAST revealed the presence of the types of soil microbes that benefit plants. KSRL was enriched with larger amounts of the primary elements important for plant growth: nitrogen, phosphorus, and potassium, and the three second tier elements. The pH of KS, LS, and KSRL were 6.40 ± 0.14, 5.87 ± 0.04, and 5.26 ± 0.02, respectively. These results could support the use of this beneficial residue for bioresource sustainability.
      Citation: Recycling
      PubDate: 2022-05-31
      DOI: 10.3390/recycling7030034
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 35: Encouraging Sustainable Use of RAP Materials
           for Pavement Construction in Oman: A Review

    • Authors: Husam Al Dughaishi, Jawad Al Lawati, Munder Bilema, Ali Mohammed Babalghaith, Nuha S. Mashaan, Nur Izzi Md. Yusoff, Abdalrhman Milad
      First page: 35
      Abstract: The Sultanate of Oman has experienced rapid development over the last thirty years and has constructed environmentally friendly and sustainable infrastructure while it continues to find economical alternative resources to achieve the goals of the Oman 2040 vision. The primary concerns are preserving natural resources and reducing the impact of carbon dioxide (CO₂) emissions on the environment. This review aims to encourage the sustainable use of reclaimed asphalt pavement (RAP) materials in pavement construction and focuses primarily on employing RAP materials in new pavement projects. Currently, new construction projects utilise a significant percentage of demolished asphalt pavement to save costs and natural resources. The key issue that arises when mixing RAP into new asphalt mixtures is the effects on the mixtures’ resistance to permanent disfigurements, such as fatigue cracks, that influence asphalt mixture performance. Numerous studies have assessed the impact of using RAP in asphalt mixtures and found that RAP increases the stiffness of asphalt mixtures, and thus improves rutting resistance at high temperatures. Nevertheless, the findings for thermal and fatigue cracking were found to be contradictory. This review will address the primary concerns regarding the use of RAP in asphalt pavements, and aims to encourage highway agencies and academic researchers in the Gulf countries to develop frameworks for the practical usage of RAP in the construction of sustainable pavement systems.
      Citation: Recycling
      PubDate: 2022-06-06
      DOI: 10.3390/recycling7030035
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 36: Does Policy on Plastic Waste Support Higher
           Waste Management Hierarchy Options'

    • Authors: Kunle Ibukun Olatayo, Paul T. Mativenga, Annlizé L. Marnewick
      First page: 36
      Abstract: There is an urgent and growing need to further advance the plastic waste management system globally and in South Africa, due to the increasing impact of plastic waste. This study focused on the adequacy of plastic policies to sustainably manage plastic waste. Policies need to address the plastic material supply systems and the options up the waste hierarchy for them to be effective and support material circularity. The study used qualitative content analysis to assess how the evolution of plastic policies for plastic waste management in South Africa aligned with national plastic material flows and promoted options higher up the waste hierarchy. This was benchmarked with Norway and Germany, which have some of the highest plastic recycling rates. The results showed that the evolution of existing plastic policies for South Africa addresses stages of production, trade and consumption, and recycling. There is no focus on waste generation, collection and sorting. None aligned with the waste hierarchy options of rethink, reduce, reuse, repair, refurbish, remanufacture and repurpose. This policy gap supports the need for broader national plastic policy frameworks that embed a policy drive in the value chain points and promote the priority higher value measures of the waste hierarchy.
      Citation: Recycling
      PubDate: 2022-06-08
      DOI: 10.3390/recycling7030036
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 37: Waste Management for Green Concrete
           Solutions: A Concise Critical Review

    • Authors: Magdalena Osial, Agnieszka Pregowska, Sławomir Wilczewski, Weronika Urbańska, Michael Giersig
      First page: 37
      Abstract: Reinforced concrete based on ordinary Portland cement (OPC) is one of the most commonly used materials in modern buildings. Due to the global growth of the building industry, concrete components have been partially or completely replaced with waste materials that can be used as binders or aggregates. Besides the ecological aspects, modern architecture widely needs materials to make the concrete durable, resisting large loads and various detrimental forces in the environment. This opens the possibilities of managing waste materials and applying them in practice. This paper presents a concise review of the green solutions for ecofriendly materials in the building industry that deal with the practical application of materials commonly treated as waste. The main emphasis was placed on their influence on the properties of the building material, optimal composition of mixtures, and discussion of the advantages and disadvantages of each of the “green” additives. It turned out that some solutions are far from being ecofriendly materials, as they leech and release numerous harmful chemicals into the environment during their presence in concrete. Finally, the paper suggests a research direction for the development of an ecofriendly structural material for a sustainable future.
      Citation: Recycling
      PubDate: 2022-06-10
      DOI: 10.3390/recycling7030037
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 38: An Overview of Packaging Waste Models in Some
           European Countries

    • Authors: Giacomo Di Foggia, Massimo Beccarello
      First page: 38
      Abstract: Efficient packaging waste management systems are essential considering recent revisions of the European legislation on packaging waste management that sets ambitious targets. European rules aim to deal with the increasing quantities of packaging waste, which cause environmental problems. Consequently, it is necessary to identify functional packaging waste management systems to achieve these targets effectively and efficiently. However, given the heterogeneity of the different packaging management systems, policymakers, scholars, and industry operators struggle to have a comparative view. The number of non-harmonized laws in force across countries, autonomous recycling targets, and constant updates are prominent problems that make it difficult to obtain comparable information for research, business, and policymaking. To fill this gap, our research question consists of assigning responsibilities for prevention, collection, recycling, and recovery and an overview of some models at a glance with respect to the general governance and functioning of the system. We base our research on a multiple-case design since more cases are examined using complementary data collection methods, analysis of the previous literature, reports, legislation, and business and institutional websites. Our results provide insights from the following cases: Germany, France, the United Kingdom, the Netherlands, Portugal, Denmark, Spain, and Italy. In addition, policy implications emerge as our insights help overcome barriers in the European market’s development caused by the different rules on packaging management and design serving policymakers that aim to harmonize the management of packaging waste. The paper also contains managerial implications for circular economy business models that can be used by managers who aim to design or upgrade their business models according to both recent legislative upgrades and packaging management systems.
      Citation: Recycling
      PubDate: 2022-06-10
      DOI: 10.3390/recycling7030038
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 39: Properties of Rubberized Concrete Prepared
           from Different Cement Types

    • Authors: Idriss, Gamal
      First page: 39
      Abstract: At present, global waste tire generation considerably exceeds consumption. Moreover, waste rubber tires (WRTs) are a cause of concern, as huge volumes are being discarded and buried, thus causing serious environmental pollution. Rubberized waste concrete (RWC) is a type of environmentally friendly construction material. The main challenge encountered when manufacturing rubberized concrete is the low adhesive properties between the cement paste and rubber particles. This paper demonstrates the effects, through experiments, of using waste tire rubber instead of recycled coarse aggregate (RCA) on two types of cement, i.e., sulfate-resistant cement (SRC) and ordinary Portland cement (OPC), where SRC is a specially blended cement designed to improve concrete performance and workability in the most aggressive environments. All tested samples contained 10% silica fume (SF) and 0.2% fly ash (FA), and the substitution of recycled aggregate content with waste rubber tier (WRT) at different percentages of 100%, 75%, and 50% was evaluated .The research investigated the synergistic effect on the workability and mechanical properties of various cement types with different amounts of rubber aggregate . It was found that the sulfate-resistant (SRC)type can increase the compressive strength than OPC with a percentage of 25% with the same content of WRT at concrete mix. Moreover, ductility and cracking behavior are improved, and it appears that it is also possible to make lightweight rubber aggregate concrete with this type of mixture. Using this type of cement, it is possible to restore satisfactory ductility to the waste tires, thus facilitating a reduction in the formation of potential plastic cracks. Moreover, the indicative compressive strength development for SRC with recycled rubber in concrete positively contributes to a reduction in formed cracks. However, SEM microstructural analyses suggest a higher proportion of C–S–H intermixed with sulfate reaction phases of SRC rubberized mortar than those of OPC; thus, given that crystal growth results in a decreased percentage of air voids rather than decreased internal cracking, it is clearly shown that the average crack width increases in OPC mortar compared with SRC. Finally, t-testing was used as an inferential statistical tool to determine whether there is a sizeable distinction between the properties of the two categories of materials, OPC and SRC, by comparing the mean and standard deviation of the values for compressive and tensile strength.
      Citation: Recycling
      PubDate: 2022-06-12
      DOI: 10.3390/recycling7030039
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 40: Rudimentary Assessment of Waste-to-Wealth of
           Used Tires Crumbs in Thermal Energy Storage

    • Authors: Hussain H. Al-Kayiem, Bilawal A. Bhayo, Elena Magaril, Pavithra Ravi
      First page: 40
      Abstract: Disposing of waste tires is a major environmental and economic issue. Different recycling methods have been studied to account for its re-usage. This project aims to evaluate the possible usage of shredded waste tires in thermal energy storage (TES) applications, whether they are sensible or latent materials. An experimental setup has been developed with seven compartments. Each compartment contains different TES materials, including tire crumbs, paraffin wax, paraffin wax with shredded tires, pebbles, pebbles with shredded tires, concrete, and concrete with shredded tires. In all cases of the mixture, the base materials are 60%vol, and the tire crumbs are 40%vol. The experimental included three locations for temperature measurements in each compartment, solar irradiation, and ambient temperature. The tests were carried out from 9:00 a.m. till 7:00 p.m. and repeated for five days to account for the weather’s daily change. Results revealed that mixed 60%vol pebbles and 40%vol shredded tires have the highest recorded temperature, at 112.5 °C, with a 39.5% increment compared to pure pebbles. The interesting finding is that the added tire crumbs reduced the storage capacity of the paraffin wax, which is latent TES material. At the same time, it increased the storage capacity of the concrete and pebbles, which are sensible TES materials. Adding 40%vol of tire crumbs to the paraffin wax has a negative effect, where the thermal storage capacity is reduced by 43%, and the discharge capacity is reduced by 57%. In contrast, the concrete and the pebbles show enhanced storage capacity. Adding 40%vol of crumbs to the concrete increased the charging capacity by 54% and discharging capacity by 33.7%. The 40%vol added tire crumbs to the pebbles increased its charging capacity by 25% and the discharging capacity by 33%. The rudimentary assessment encourages further investigations on using the wasted tires crumbs for TES. The results reveal the probability of a circular economy using wasted tires with sensible TES for solar-to-thermal energy conversion.
      Citation: Recycling
      PubDate: 2022-06-13
      DOI: 10.3390/recycling7030040
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 41: Assessing Alternative Supporting Organic
           Materials for the Enhancement of Water Reuse in Subsurface Constructed
           Wetlands Receiving Acid Mine Drainage

    • Authors: Martha M. Oberholzer, Paul J. Oberholster, Luyanda L. Ndlela, Anna-Maria Botha, Johannes C. Truter
      First page: 41
      Abstract: Acid mine drainage (AMD) is a global problem with severe consequences for the environment. South Africa’s abandoned mines are a legacy from the country’s economic dependence on the mining sector, with consequent negative impacts on ecosystems. AMD remediation includes active and passive techniques. Constructed wetlands (a passive technique) have lower operational costs but require larger spaces and longer timeframes to achieve the remediation of AMD, and are supported by anaerobic sulphate-reducing bacteria (SRB), which capable of remediating high-sulphate-laden AMD while precipitating dissolved metals from the AMD. Organic substrates supporting these activities are often the limiting factor. When enhancing existing passive AMD remediation technologies, alternative waste material research that may support SRB activity is required to support the circular economy through the reduction in waste products. Chicken feathers show potential as a substrate enhancer, boosting organic carbon availability to SRB, which sustains passive AMD treatment processes by achieving pH elevation, sulphate and metal reductions in AMD water for reuse. Microbial biodiversity is essential to ensure the longevity of passive treatment systems, and chicken feathers are proven to have an association with SRB microbial taxa. However, the longer-term associations between the AMD water parameters, microbial diversity and the selected substrates remain to be further investigated.
      Citation: Recycling
      PubDate: 2022-06-14
      DOI: 10.3390/recycling7030041
      Issue No: Vol. 7, No. 3 (2022)
  • Recycling, Vol. 7, Pages 11: Assessment of Performance and Challenges in
           Use of Commercial Automated Sorting Technology for Plastic Waste

    • Authors: Cesar Lubongo, Paschalis Alexandridis
      First page: 11
      Abstract: Recycling plastic is an important step towards a circular economy. Attaining high-quality recycled plastics requires the separation of plastic waste by type, color, and size prior to reprocessing. Automated technology is key for sorting plastic objects in medium- to high-volume plants. The current state of the art of commercial equipment for sorting plastic as well as challenges faced by Material Recovery Facilities (MRFs) to sort post-consumer plastics are analyzed here. Equipment for sorting plastic recyclables were identified using publicly available information obtained from manufacturers’ websites, press releases, and journal articles. Currently available automated sorting equipment and artificial intelligence (AI)-based sorters are evaluated regarding their functionality, efficiency, types of plastics they can sort, throughput, and accuracy. The information compiled captures the progress made during the ten years since similar reports were published. A survey of MRFs, reclaimers, and brokers in the United States identified methods of sorting used for plastic, sorting efficiency, and current practices and challenges encountered at MRFs in sorting plastic recyclables. The commercial sorting equipment can address some of the challenges that MRFs face. However, sorting of film, multilayered, blended, or mixed-material plastics is problematic, as the equipment is typically designed to sort single-component materials. Accordingly, improvements and/or new solutions are considered necessary.
      Citation: Recycling
      PubDate: 2022-02-23
      DOI: 10.3390/recycling7020011
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 12: Special Issue “The Use of Recycled
           Materials to Promote Pavement Sustainability Performance”

    • Authors: José Neves, Ana Cristina Freire
      First page: 12
      Abstract: Recycling road pavement materials allows for a more sustainable use of raw materials and contributes to creating a circular economy [...]
      Citation: Recycling
      PubDate: 2022-02-23
      DOI: 10.3390/recycling7020012
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 13: Modelling and Simulation of Building Material
           Flows: Assessing the Potential for Concrete Recycling in the German
           Construction Sector

    • Authors: Clemens Mostert, Christian Weber, Stefan Bringezu
      First page: 13
      Abstract: The reuse and recycling of materials can make an important contribution to the conservation of natural resources in the sense of a circular economy. This applies in particular to high quality recycling, supporting the material use of waste and closing product cycles. The construction sector is the most important sector in terms of available volume of materials for recycling. However, the largest share of recycling (RC) materials goes predominantly into road construction and underground engineering. This research developed a dynamic model and used a simulation tool to calculate future building material flows in the German construction sector of residential buildings to explore the medium- and long-term potential for RC concrete. The results show that, by increasing the RC rate of concrete to produce recycled aggregates for concrete (RAC) from currently 1.5% to 48%, up to 179 million tons of sand and gravel could be saved until 2060. If the current maximum secondary input rate of RAC of 45% is increased to 70%, the savings could rise over another 66 million tons. If a secondary input rate of 100% is applied, RAC could completely fulfill the demand for sand and gravel for new residential building in Germany from 2045 onwards. The approval of RC concrete for more concrete strength and exposure classes is required to avoid a surplus of RAC and a rapid exhaustion of landfill capacities in the future.
      Citation: Recycling
      PubDate: 2022-03-01
      DOI: 10.3390/recycling7020013
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 14: Application of Electrodialysis for the
           Selective Lithium Extraction Towards Cobalt, Nickel and Manganese from
           Leach Solutions Containing High Divalent Cations/Li Ratio

    • Authors: Soumaya Gmar, Alexandre Chagnes, Florence Lutin, Laurence Muhr
      First page: 14
      Abstract: The present work aims at investigating the potentialities of implementation of electrodialysis for the recycling of spent lithium-ion batteries. In this work, the use of highly-selective membrane toward lithium(I) in electrodialysis was investigated to recover selectively lithium(I) toward cobalt(II), nickel(II) and manganese(II) by means of monovalent ion-selective membranes. It was shown that the presence of divalent cations in the leach solution is responsible for a significant decrease of the limiting current despite an increase in ionic conductivity. Therefore, monitoring the ionic conductivity was not sufficient to operate electrodialysis under optimal conditions, especially when highly selective membranes were used. Furthermore, it was demonstrated that the current has to be lower than the limiting current to avoid metal hydroxide precipitation into the membrane porosity by monitoring the limiting current over time.
      Citation: Recycling
      PubDate: 2022-03-02
      DOI: 10.3390/recycling7020014
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 15: Factors That Affect Methane Yield Using Raw
           Olive Alperujo (Unhydrolyzed) as Substrate in BMP Assays

    • Authors: Valentina Ortega, Andrés Donoso-Bravo, Rolando Chamy-Maggy, José Luis Campos, Anuska Mosquera-Corral, Marisol Belmonte
      First page: 15
      Abstract: The olive alperujo (OA) corresponds to the solid waste generated in the olive oil extraction process using the two-phase centrifugation method. OA is produced in large quantities (800 kg OA/ton olives processed) and is characterized by its high moisture content, organic matter, and low pH. In Chile, the olive oil industry is recent, and one of its main challenges is to be able to manage OA to reduce the impact caused by its disposal. In this sense, its valorization as biogas by means of anaerobic digestion is an economically attractive option. For this, it is previously necessary to evaluate the biomethane potential (BMP) of the raw OA using batch assays. This study was focused on evaluating the factors that most affect the methane yield (MY) when using OA as substrate in BMP tests. First, a sweep analysis (Plackett–Burman) was applied to determine those factors that, according to the literature, would have an influence on the BMP tests. Among the factors studied, the most significant were preincubation, OA concentration, and agitation level. Subsequently, a 23 factorial experimental design was applied to evaluate the effect of these factors on MY at different levels. Results show that the OA concentration was the most significant factor affecting MY.
      Citation: Recycling
      PubDate: 2022-03-04
      DOI: 10.3390/recycling7020015
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 16: Evaluation of the Performance of Two
           Australian Waste-Plastic-Modified Hot Mix Asphalts

    • Authors: Nuha S. Mashaan, Amin Chegenizadeh, Hamid Nikraz
      First page: 16
      Abstract: The construction of hundreds of kilometres of roads around the world every year results in the consumption of large amounts of raw materials and the depletion of natural resources. In addition, technologically advanced countries such as Australia are currently facing a major issue regarding the waste materials produced daily by their citizens. The disposal of these waste materials is a critical issue faced by municipalities in modern cities. Currently, using waste materials in civil and construction engineering is of great interest to researchers and industry. This study investigates the impact of using waste polyethylene terephthalate to modify asphalt mixtures following Australian design guidelines and criteria. Different types of asphalt are used to investigate and determine the mechanical properties of modified asphalt mixtures. The Marshall stability, Marshall flow, Marshall quotient, and wheel-tracking tests were tested. The Marshall stability, Marshall flow, and MQ of the Marshall test results exhibited significant improvements when using PET in modified SMA and AC mixtures. It can be seen that the 8% PET produced a mixture with the highest stability of 19.78 kN. The lowest rut depth was about 2.08 mm for samples modified with 8% PET.
      Citation: Recycling
      PubDate: 2022-03-04
      DOI: 10.3390/recycling7020016
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 17: Assessment of Belief Constructs to Support an
           Intervention in Municipal Solid Waste Separation at the Source in
           Low–Middle-Income Countries: Observations from the Greater Accra
           Region of Ghana

    • Authors: Kwaku Oduro-Appiah, Abraham Afful, Henrietta Osei-Tutu
      First page: 17
      Abstract: This article uses a modified model of the theory of planned behaviour to assess salient beliefs of household heads towards the separation of municipal solid waste at its source in the Greater Accra Region of Ghana. Structural equation modelling was used to analyse the responses of 598 household heads to a questionnaire in a cross-sectional design. Whilst the default model produced an acceptable fit to the data and explained 37% of the variance in households’ intention to separate waste at its source, the modified model with moral norms as an additional construct fitted the data excellently, explaining 52% of the variance in intention. Moral norms and perceived behavioural control were the predominant latent constructs to influence intentions. Control beliefs related to the availability of waste receptacles, provision of regular waste collection services, and access to knowledge of the separation process had the greatest tendency to facilitate households’ intentions. Pro-environmental interventions designed in a participatory manner to promote moral correctness, responsibility, respect for the environment, and positive affect may empower households to separate waste at its source. This research contributes to the development of a municipal solid waste strategy in the region, and may further support research in waste diversion and the circular economy in other jurisdictions.
      Citation: Recycling
      PubDate: 2022-03-09
      DOI: 10.3390/recycling7020017
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 18: A Comparison on Physical and Rheological
           Properties of Three Different Waste Plastic-Modified Bitumen

    • Authors: Nuha Mashaan, Amin Chegenizadeh, Hamid Nikraz
      First page: 18
      Abstract: This study aims to investigate the effect and the possibility of using waste plastic as a sustainable cost-effective polymer to modify bitumen binders. Different types of waste plastic have been used in this modification, including polyethylene terephthalate (PET), high-density polyethylene (HDPE), and low-density polyethylene (LDPE). The modification targets the physical characteristics, rheological properties, and binders’ resistance to ageing. Both long- and short-term ageing are investigated to determine the durability and ageing resistance of the modified binder using rolling thin film oven tests (RTFOT) and pressure ageing vessels (PAVs). Penetration tests and dynamic shear rheometer (DSR) tests were conducted to investigate and evaluate the complex shear modulus, stiffness, elasticity, and viscous properties. The results show that 2% and 4% of HDPE and LDPE are recommended as ideal contents for good performance, as reflected by the penetration tests before and after ageing. However, higher contents, such as 6% and 8% HDPE and LDPE, are not significant in improving the stiffness, elasticity, and ageing resistance. Therefore, samples of 6–8% HDPE and LDPE are more vulnerable to permanent deformation. Furthermore, using waste PET exhibits obvious improvements in terms of the physical characteristics, rheological properties, stiffness, elasticity, and ageing resistance with up to 8% PET-modified bitumen. Based on the results, the ideal type and content is 6–8% PET waste plastic.
      Citation: Recycling
      PubDate: 2022-03-11
      DOI: 10.3390/recycling7020018
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 19: Life Cycle Assessment of Existing and
           Alternative Options for Municipal Solid Waste Management in Saint
           Petersburg and the Leningrad Region, Russia

    • Authors: Anna Zaikova, Natalia Vinitskaia, Ivan Deviatkin, Jouni Havukainen, Mika Horttanainen
      First page: 19
      Abstract: A waste reform was recently introduced in Russia to divert waste from landfills. To help advance the reform, this paper presents a life cycle assessment of the municipal solid waste management system in Russia’s second largest city—Saint Petersburg—and its neighboring Leningrad region. Five scenarios were evaluated: the current state of the system (S0), its expected post-reform state in 2024 (S1), and its state improved by increased landfill gas collection (S2), by increased waste incineration (S3), and by separate collection of waste (S4). The environmental impact was assessed in terms of climate change, acidification, eutrophication, and abiotic resource depletion (fossil fuels). The results showed an overall reduction in the environmental impact of the waste management system across all impact categories and all scenarios studied. The largest reduction in all impact categories (except abiotic resource depletion) was achieved through source separation of municipal solid waste. Particularly, global warming potential was reduced from 0.328 kg CO2-eq./kg waste generated in S0 to 0.010 kg CO2-eq./kg waste in S4. Regarding abiotic resource depletion potential (fossil fuels), the incineration scenario is the most beneficial, since it reduces the impact by 573%.
      Citation: Recycling
      PubDate: 2022-03-14
      DOI: 10.3390/recycling7020019
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 20: Promising Developments in Bio-Based Products
           as Alternatives to Conventional Plastics to Enable Circular Economy in

    • Authors: Tetiana Shevchenko, Meisam Ranjbari, Zahra Shams Esfandabadi, Yuriy Danko, Kseniia Bliumska-Danko
      First page: 20
      Abstract: Transforming the plastic industry toward producing more sustainable alternatives than conventional plastics, as an essential enabler of the bio-based circular economy (CE), requires reinforcing initiatives to drive solutions from the lab to the market. In this regard, startups and ideation and innovation events can potentially play significant roles in consolidating efforts and investments by academia and industry to foster bio-based and biodegradable plastic-related developments. This study aimed to present the current trends and challenges of bioplastics and bio-based materials as sustainable alternatives for plastics. On this basis, having conducted a systematic literature review, the seminal research themes of the bio-based materials and bioplastics literature were unfolded and discussed. Then, the most recent developments of bio-based sustainable products in Ukraine, as alternatives to petroleum-based plastics, that have gained publicity through local startup programs and hackathons were presented. The findings shed light on the potential of the bio-based sector to facilitate the CE transition through (i) rendering innovative solutions most of which have been less noticed in academia before; (ii) enhancing academic debate and bridging the gap between developers, scholars, and practitioners within the plastic industry toward creating circularity across the supply chain; (iii) identifying the main challenges and future perspectives for further investigations in the future.
      Citation: Recycling
      PubDate: 2022-03-25
      DOI: 10.3390/recycling7020020
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 21: Potential of Alternative Organic Binders in
           Briquetting and Enhancing Residue Recycling in the Steel Industry

    • Authors: Elsayed Mousa, Hesham Ahmed, Daniel Söderström
      First page: 21
      Abstract: Steel production generates various types of residues that cannot be directly recycled in the production process without pre-treatment and agglomeration. In the present study, recipes were designed to develop briquettes in a blast furnace (BF) with the partial replacement of cement with alternative commercial organic binders, including molasses–lime, bitumen, keracoal, carboxymethyl cellulose, and wood tar. The briquettes were produced using a technical-scale vibrating machine and the mechanical strength was evaluated using drop test and standard tumbler index results. The reduction behaviour was investigated by thermogravimetric analysis (TGA) coupled with QMS. A heat and mass balance model (MASMOD) was used to evaluate the potential of developed briquettes to reduce the energy consumption and CO2 emissions from the BF. Although cement was superior in developing mechanical strength, bitumen was the best among the other alternative organic binders and provided sufficient strength to the briquettes at 2.0% addition, which corresponded to 18.2% replacement of total cement. The briquettes containing bitumen possessed a higher reduction rate and lower activation energy compared to cement. The MASMOD calculation demonstrated that the developed briquettes have the potential to provide annual savings of 15,000–45,000 tons of lump coke, 4500–19,500 tons of CO2 emissions, and 5000–20,000 tons of limestone in Swedish BFs.
      Citation: Recycling
      PubDate: 2022-04-01
      DOI: 10.3390/recycling7020021
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 22: Recovery and Use of Recycled Carbon Fibers
           from Composites Based on Phenol-Formaldehyde Resins

    • Authors: Yuliya Kulikova, Natalia Sliusar, Vladimir Korotaev, Olga Babich, Viktoria Larina, Svetlana Ivanova
      First page: 22
      Abstract: The technical feasibility of the recycling of specific polymeric composite materials was evaluated. Two types of carbon composites, both with phenol-formaldehyde resin but with different reinforcement, were studied. It was discovered that the solvolysis with the oxidizing agents used in an acidic environment allowed for the achievement of a high-efficiency fiber extraction. The extracted secondary carbon fibers had a high degree of purity (95–99.5% of resin was removed). Fiber thickness slightly decreased during the process (on average, by 20%). The use of chopped secondary fibers (3–9 mm fiber length) for concrete reinforcement produced a positive effect. Hence, the compressive and bending strength of the concrete blocks were accordingly 1.5% and 16% higher in comparison with the control sample. The use of secondary carbon fabric for the production of composite materials a good result: the effective tensile strength of CFRP samples reinforced with recovered fabric is only lower by 4.5% in comparison with virgin fabric.
      Citation: Recycling
      PubDate: 2022-04-02
      DOI: 10.3390/recycling7020022
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 23: Biofuel Generation from Potato Peel Waste:
           Current State and Prospects

    • Authors: Omojola Awogbemi, Daramy Vandi Von Kallon, Adefemi O. Owoputi
      First page: 23
      Abstract: Growing environmental concerns, increased population, and the need to meet the diversification of the source of global energy have led to increased demand for biofuels. However, the high cost of raw materials for biofuels production has continued to slow down the acceptability, universal accessibility, and affordability of biofuels. The cost of feedstock and catalysts constitutes a major component of the production cost of biofuels. Potato is one of the most commonly consumed food crops among various populations due to its rich nutritional, health, and industrial benefits. In the current study, the application of potato peel waste (PPW) for biofuel production was interrogated. The present state of the conversion of PPW to bioethanol and biogas, through various techniques, to meet the ever-growing demand for renewable fuels was reviewed. To satisfy the escalating demand for biohydrogen for various applications, the prospects for the synthesis of biohydrogen from PPW were proposed. Additionally, there is the potential to convert PPW to low-cost, ecologically friendly, and biodegradable bio-based catalysts to replace commercial catalysts. The information provided in this review will enrich scholarship and open a new vista in the utilization of PPW. More focused investigations are required to unravel more avenues for the utilization of PPW as a low-cost and readily available catalyst and feedstock for biofuel synthesis. The application of PPW for biofuel application will reduce the pump price of biofuels, ensure the appropriate disposal of waste, and contribute towards environmental cleanliness.
      Citation: Recycling
      PubDate: 2022-04-05
      DOI: 10.3390/recycling7020023
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 24: Enzymatic Glucose and Xylose Production from
           Paper Mill Rejects

    • Authors: Joseph Rauzi, Ulrike Tschirner
      First page: 24
      Abstract: Recycled paper fiber rejects have shown potential as a source of waste-to-resource carbohydrates for renewable chemicals production. This study examined three classes of recycled paper fines (old corrugated containers, old newspaper, and mixed office waste) and two industrial papermaking rejects streams from different recycling mills (one mill processes linerboard and the other old corrugated cardboard). The effect of chemical pretreatment using dilute sodium hydroxide, hot water and dilute sulfuric acid on enzymatic glucose and xylose yields was evaluated. Enzymatic hydrolysis results indicated that recycled fiber streams with more old corrugated cardboard have higher potential to produce carbohydrates. The recycled cardboard rejects produced more glucose and xylose per kilogram of rejects than the linerboard rejects under all untreated and pretreated conditions. The highest producing rejects sample was sodium hydroxide pretreated cardboard rejects with 373 g glucose and 61 g xylose produced per kilogram of rejects. However, a simple hot water pretreatment showed similar results, with 335 g glucose and 58 g xylose produced per kilogram of rejects. The hot water pretreatment is recommended due to its comparable yield and lower chemical addition.
      Citation: Recycling
      PubDate: 2022-04-13
      DOI: 10.3390/recycling7020024
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 25: Recycling of Pretreated Polyolefin-Based
           Ocean-Bound Plastic Waste by Incorporating Clay and Rubber

    • Authors: Shawn Martey, Keith Hendren, Nicholas Farfaras, Jesse C. Kelly, Matthew Newsome, Izabela Ciesielska-Wrobel, Margaret J. Sobkowicz, Wan-Ting Chen
      First page: 25
      Abstract: Plastic waste found in oceans has become a major concern because of its impact on marine organisms and human health. There is significant global interest in recycling these materials, but their reclamation, sorting, cleaning, and reprocessing, along with the degradation that occurs in the natural environment, all make it difficult to achieve high quality recycled resins from ocean plastic waste. To mitigate these limitations, various additives including clay and rubber were explored. In this study, we compounded different types of ocean-bound (o-HDPE and o-PP) and virgin polymers (v-LDPE and v-PS) with various additives including a functionalized clay, styrene-multi-block-copolymer (SMB), and ethylene-propylene-based rubber (EPR). Physical observation showed that all blends containing PS were brittle due to the weak interfaces between the polyolefin regions and the PS domains within the polymer blend matrix. Blends containing clay showed rough surfaces and brittleness because of the non-uniform distribution of clay particles in the polymer matrix. To evaluate the properties and compatibility of the blends, characterizations using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and small-amplitude oscillatory shear (SAOS) rheology were carried out. The polymer blend (v-LDPE, o-HDPE, o-PP) containing EPR showed improved elasticity. Incorporating additives such as rubber could improve the mechanical properties of polymer blends for recycling purposes.
      Citation: Recycling
      PubDate: 2022-04-14
      DOI: 10.3390/recycling7020025
      Issue No: Vol. 7, No. 2 (2022)
  • Recycling, Vol. 7, Pages 1: An Empirical Study on the Main Determinants of
           Recycling Plastic Waste in Tunisia

    • Authors: Lamia Ben Amor, Sami Hammami
      First page: 1
      Abstract: Over the past fifteen years, numerous policies for recycling and recovering waste have been implemented throughout the world. Tunisia is among the countries considering recycling as a sustainable development path. This empirical study aimed to investigate and examine the influence of financial determinants measured by the price of waste disposal (PDI), institutional determinants measured by the collection of waste (CW) and the number of drop-off recycling centers, and ordinance and demographic determinants measured by the population density and the recycling rate for plastic as a domestic waste based on a panel of 24 Tunisian governorates over the 2001–2020 period. It is concluded from the empirical findings that all exogenous variables except population density have a significant effect on the recycling rate.
      Citation: Recycling
      PubDate: 2022-01-06
      DOI: 10.3390/recycling7010001
      Issue No: Vol. 7, No. 1 (2022)
  • Recycling, Vol. 7, Pages 2: Baseline Data of Low-Density Polyethylene
           Continuous Pyrolysis for Liquid Fuel Manufacture

    • Authors: Aleksandr Ketov, Vladimir Korotaev, Natalia Sliusar, Vladivir Bosnic, Marina Krasnovskikh, Aleksei Gorbunov
      First page: 2
      Abstract: The recycling of end-of-life plastics is a problem, since small parts can be returned into circulation. The rest is burned, landfilled or recycled into low-quality heating oil by pyrolysis methods. The disadvantages of this method are the need to dispose the formed by-product, pyrolytic carbon, the poor quality of produced liquid fuel and the low productivity of the method associated with the periodicity of the process. In this work, methods of thermogravimetry and chromatography–mass spectrometry (GC-MS) have been used to study the co-pyrolysis products of low-density polyethylene (LDPE) and oxygen-containing substances at the pressures of 4–8 MPa and temperatures of 520–620 °C. Experiments have highlighted the conditions needed for producing of high-quality liquid fuel. Initial data have been prepared for the design of a continuous pyrolysis reactor to dispose polymer waste for the production of bio-oil which would be available to enter the petrochemical products market.
      Citation: Recycling
      PubDate: 2022-01-12
      DOI: 10.3390/recycling7010002
      Issue No: Vol. 7, No. 1 (2022)
  • Recycling, Vol. 7, Pages 3: Acknowledgment to Reviewers of Recycling in

    • Authors: Recycling Editorial Office Recycling Editorial Office
      First page: 3
      Abstract: Rigorous peer-reviews are the basis of high-quality academic publishing [...]
      Citation: Recycling
      PubDate: 2022-01-20
      DOI: 10.3390/recycling7010003
      Issue No: Vol. 7, No. 1 (2022)
  • Recycling, Vol. 7, Pages 4: Critical Evaluation of the Potential of
           Organic Acids for the Environmentally Friendly Recycling of Spent
           Lithium-Ion Batteries

    • Authors: Eva Gerold, Clemens Schinnerl, Helmut Antrekowitsch
      First page: 4
      Abstract: The need to recover valuable metals from spent lithium-ion batteries (LIBs) is undisputed. However, the environment and the climate are also affected by emissions from the recycling processes. Therefore, the call for environmentally friendly recycling methods is currently louder than ever. In the field of hydrometallurgical recovery of metals from spent LIBs, inorganic acids have so far proved to be an effective, but environmentally problematic, leaching agent, since the pollution of wastewater by high salt loads and the emission of toxic gases cannot be avoided. This has recently led to a trend towards the application of organic acids, as these have significantly more environmentally friendly properties. In order to continue this approach, and to improve it even further from an environmental point of view, this work focuses on the utilization of low leaching temperatures in combination with organic acids for the recovery of valuable metals from spent lithium-ion batteries. This can drastically reduce the required energy demand. Furthermore, attention is paid to higher (50–100 g·L−1) solid-liquid ratios, which are indispensable, especially with regard to the economic establishment of the tested process. The experimental verification of the feasibility using citric, oxalic, and formic acid showed the possibility of an efficient recovery of cobalt, nickel, and lithium. In particular, citric acid in combination with hydrogen peroxide as a reducing agent appears to be a suitable and environmentally friendly alternative to classical inorganic acids, even at low process temperatures, for the hydrometallurgical recycling of lithium-ion batteries.
      Citation: Recycling
      PubDate: 2022-01-31
      DOI: 10.3390/recycling7010004
      Issue No: Vol. 7, No. 1 (2022)
  • Recycling, Vol. 7, Pages 5: Effect of Graphite on the Recovery of Valuable
           Metals from Spent Li-Ion Batteries in Baths of Hot Metal and Steel

    • Authors: Elsayed Mousa, Xianfeng Hu, Guozhu Ye
      First page: 5
      Abstract: The recycling of valuable metals from spent lithium-ion batteries (LIBs) is highly important to secure the sustainable production of new LIBs and reduce the dependence on virgin resources. The present paper aims to study the smelting behaviour of black mass (BM) from spent LIBs and investigate the effect of graphite on metal recovery in a carbon-saturated hot metal bath and in a low-carbon steel bath. The smelting trials of BM were conducted in a technical scale (150 kg) induction furnace using hot metal and steel scrap at operating temperatures in the range of 1278–1438 °C and 1470–1610 °C, respectively. Two grades of BM were applied in the current study; high-Ni BM and high-Co BM. Parts of both grades of the BM were briquettes to enhance the direct reduction of metal oxides with embedded graphite and to reduce the dust generation during loading into the furnace. The briquette BM was charged to carbon-saturated hot metal bath while the other part of the BM was subjected to de-coking in a muffle furnace in an oxidising atmosphere to remove graphite (37–39%) and to concentrate the valuable metals in the BM. The de-coked BM was loaded directly, without the need for the briquette, to the low-carbon steel bath. The results indicated that smelting of the de-coked BM in a steel bath is more efficient in metal recovery than the smelting of the corresponding briquette BM in a molten hot metal bath. The highest recovery rate of Co, Ni and Cu (98–99%) was obtained by smelting de-coked high-Co BM in a low-carbon molten steel bath, while the lowest recovery rate (38–55%) was obtained by smelting the briquette high-Ni BM in the carbon-saturated hot metal bath.
      Citation: Recycling
      PubDate: 2022-02-03
      DOI: 10.3390/recycling7010005
      Issue No: Vol. 7, No. 1 (2022)
  • Recycling, Vol. 7, Pages 6: Embodied Energy in Pyrolysis and Solvolysis
           Approaches to Recycling for Carbon Fiber-Epoxy Reinforced Composite Waste

    • Authors: Komal Kooduvalli, John Unser, Soydan Ozcan, Uday K. Vaidya
      First page: 6
      Abstract: Carbon fiber composites are increasingly used in aerospace, motorcycles, sporting, and high-performance vehicles, and their end of life recycling is of growing interest. This study deals with the life cycle assessment (LCA) of carbon fiber reinforced plastics (CFRP) waste streams. The embodied energy (EE) of recycling CFRP via two viable methods—i.e., pyrolysis and solvolysis—is studied. Both pyrolysis and solvolysis were studied for EE with different variants. Alongside fiber recovery from CFRP, the pyrolysis process calculations consider energy recovery from syngas and oil produced within the system. For pyrolysis, electric furnace and natural gas were primarily considered. For solvolysis, different solvent scenarios were considered, including (a) deionized water, (b) water and potassium hydroxide, (c) acetone and water, and (d) water with acetic acid and potassium hydroxide. Energy reduction from one generation to the next has also been highlighted. The EE for recycling CFRP is quantified and discussed for these scenarios in this paper.
      Citation: Recycling
      PubDate: 2022-02-14
      DOI: 10.3390/recycling7010006
      Issue No: Vol. 7, No. 1 (2022)
  • Recycling, Vol. 7, Pages 7: Energy Potential Assessment of Excavated
           Landfill Material: A Case Study of the Perm Region, Russia

    • Authors: Iuliia Shcherbinina, Stepan Polygalov, Galina Ilinykh, Vladimir Korotaev, Natalia Sliusar, Ivana Mihajlovic, Nemanja Stanisavljevic
      First page: 7
      Abstract: The paper presents results of field and laboratory studies of thermal characteristics to excavated landfill waste in Perm region, Russia. The peculiarity of the study includes the following aspects: waste composition with a high share of polymers, the climatic conditions of the territory and the lack of engineering infrastructure at the waste disposal facility. When determining the waste composition and thermal properties of waste, it is proposed to include a stage of removal of contamination from landfilled waste fraction, since their share of contamination can reach up to 33%. This stage will allow researchers to adjust the net calorific value of the excavated waste without overestimation, which may affect decision-making when implementing waste management technology. Among combustible components with the highest moisture content are waste paper (69.1%) and diapers (65.8%), whereas wood (11.2%), PET bottles (3.1%) and other 3D plastics (13.4%) have rather low ash content on a dry basis. Calculation of thermal properties and analysis of the energy potential of the waste samples was conducted based on the obtained data. The calorific value of the individual components and excavated waste depends not only on the moisture and ash content of the individual components, but also on the presence of contaminants. The average net calorific value of the excavated waste is 4.9 MJ/kg, and for the separate mixture of combustible components, it is 7.5 MJ/kg at a moisture content of 44%. Excavated landfill waste can be regarded as a resource for the manufacture of secondary fuel only after pretreatment that includes at least sorting and drying. The results of this study may be useful in developing technologies needed to eliminate old MSW dumps and old landfills, for the development of the concept of circular economy and prevention of environmental degradation problems.
      Citation: Recycling
      PubDate: 2022-02-15
      DOI: 10.3390/recycling7010007
      Issue No: Vol. 7, No. 1 (2022)
  • Recycling, Vol. 7, Pages 8: Physicochemical and Biological Contribution of
           Native Macrophytes in the Constructed Wetlands to Treat Municipal
           Wastewater: A Pilot-Scale Experiment in a Sub-Tropical Climate Region

    • Authors: Tofeeq Aalam, Carlos Alberto Arias, Nadeem Khalil
      First page: 8
      Abstract: In this study, the physicochemical and biological contributions of different macrophytes in horizontal sub-surface flow constructed wetlands (HSSF-CWs) to treat low-strength municipal wastewater operated at high hydraulic loads under a sub-tropical climatic region is investigated. Out of the four identical beds, three were planted with locally available macrophytes (P. australis, Sagittaria, and Iris), whereas one bed was kept as a control. The beds were filled with media and operated in parallel continuously for eight months, with increasing the surface loading rate (SLR) from 0.19 to 2.78 m day−1. The results indicate that the planted beds performed significantly (p < 0.01) better to remove TSS (70% to 78%), BOD5 (66% to 77%), COD (59% to 75%), NO3-N (56% to 64%), NH4-N (41% to 69%), TN (36% to 41%), and TP (44% to 61%) as compared to the unplanted bed for the same parameters (48%, 39%, 40%, 33%, 18%, 20%, and 29%, respectively). The presence of macrophytes in HSSF-CWs was found to be highly significant. The average relative growth rate (RGR) was observed in the order of P. australis (0.0086 day−1) > Sagittaria (0.0061 day−1) > Iris (0.0059 day−1). When compared to the performances of the species used, Sagittaria and P. australis produced better results than Iris. The investigations on biomass showed that Sagittaria yielded higher production, followed by P. australis and Iris. The proportions of uptake by the macrophytes were found to be 9.3%, 6.3%, and 3.9% of mass N removal, and 7.6%, 5.1%, and 4.4% of mass p removal in Sagittaria, P. australis, and Iris, respectively. This study contributes to the effective response to the environment, which validates a major role of macrophytes and their disparate response to pollutant removal processes by different species from municipal wastewater through HSSF-CWs.
      Citation: Recycling
      PubDate: 2022-02-17
      DOI: 10.3390/recycling7010008
      Issue No: Vol. 7, No. 1 (2022)
  • Recycling, Vol. 7, Pages 9: Intelligent and Real-Time Detection and
           Classification Algorithm for Recycled Materials Using Convolutional Neural

    • Authors: Dimitris Ziouzios, Nikolaos Baras, Vasileios Balafas, Minas Dasygenis, Adam Stimoniaris
      First page: 9
      Abstract: In recent years, the production of municipal solid waste has constantly been increasing. Recycling is becoming more and more important, as it is the only way that we can have a clean and sustainable environment. Recycling, however, is a process that is not fully automated; large volumes of waste materials need to be processed manually. New and novel techniques have to be implemented in order to manage the increased volume of waste materials at recycling factories. In this paper, we propose a novel methodology that can identify common waste materials as they are being processed on a moving belt in waste collection facilities. An efficient waste material detection and classification system is proposed, which can be used in real integrated solid waste management systems. This system is based on a convolutional neural network and is trained using a custom dataset of images, taken on site from actual moving belts in waste collection facilities. The experimental results indicate that the proposed system can outperform existing algorithms found in the literature in real-world conditions, with 92.43% accuracy.
      Citation: Recycling
      PubDate: 2022-02-18
      DOI: 10.3390/recycling7010009
      Issue No: Vol. 7, No. 1 (2022)
  • Recycling, Vol. 7, Pages 10: Evaluation of Vermicompost Produced by Using
           Post-Consumer Cotton Textile as Carbon Source

    • Authors: Vijaypal Singh, Jordan Wyatt, Ali Zoungrana, Qiuyan Yuan
      First page: 10
      Abstract: A large amount of textile waste is generated every year around the globe. The textile product made from natural fibers might be vermicomposted and used as fertilizer. The present study aimed to research an integrated system of pre-composting (pathogen kill) and vermicomposting with various levels of post-consumer cotton waste to determine if this addition has any effects on the composting process. A vermicompost bin was constructed and filled with feedstocks mixed with post-consumer cotton textile waste at a 25:1 C:N ratio, and operated for three months at approximately 70% moisture content, with four composting trials with 0 g (control), 100 g, 200 g, and 300 g of textile waste. The pre-composting stage reached a temperature ranging from 40 °C to 50 °C, able to neutralize the pathogens. All four trials resulted in final compost with C: N ratios around 14, proving that post-consumer cotton textile waste did not affect the vermicomposting process, and was successfully used as a carbon source by worms to produce a healthy and mature compost. This indicates a sustainable option for the recovery of textile waste that is being decomposed in landfills.
      Citation: Recycling
      PubDate: 2022-02-21
      DOI: 10.3390/recycling7010010
      Issue No: Vol. 7, No. 1 (2022)
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