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Recycling, Volume 6, Issue 2 (June 2021) – 20 articles

Cover Story (view full-size image): Recycling of critical metals from spent devices is a requirement for the sustainability of the planet and to establish a circular economy. This is an article on the development of a leaching scheme to allow high platinum recoveries and minimize aluminum dissolution, facilitating the application of solvent extraction. The replacement of some of the hydrochloric acid by calcium chloride in the leaching step did not compromise the platinum recovery (in the range 75–85%). The tested thiodiglycolamide derivative—N,N’-dimethyl-N,N’-dicyclohexylthiodiglycolamide—in toluene revealed a substantial loading capacity for both platinum and iron after contact with the spent automotive catalyst leaching solution; however, iron scrubbing and platinum stripping from the organic phases were not successful and, thus, needed improvement. View this paper
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Article
Mechanical Properties of Tin Slag Mortar
Recycling 2021, 6(2), 42; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020042 - 21 Jun 2021
Viewed by 557
Abstract
The increased demand for cement mortar due to rapid infrastructural growth and development has led to an alarming depletion of fine aggregate. This has prompted the need for a more sustainable material as a total/partial replacement for natural fine aggregate. This study proposes [...] Read more.
The increased demand for cement mortar due to rapid infrastructural growth and development has led to an alarming depletion of fine aggregate. This has prompted the need for a more sustainable material as a total/partial replacement for natural fine aggregate. This study proposes the use of tin slag (TS) as a replacement for fine aggregate in concrete to bridge this sustainability gap. TS was used to replace fine aggregate at replacement levels of 0%, 25%, 50%, 75%, and 100% in cement mortar. Fresh and hardened properties of TS mortar were obtained. Flow tests showed that, as the TS quantity and the w/c ratio increased, the mortar flow increased. Similarly, the compressive strength increased as the TS replacement increased up to 50% replacement, after which a decline in strength was observed. However, with the TS replacement of fine aggregate up to 100%, a compressive strength of 6% above control was attained. The morphological features confirm that specimens with TS had a denser microstructure because of its shape characteristics (elongated, irregular, and rough), and, thus, plugged holes better than the control mortar. The natural sand’s contribution to strength was a result of better aggregate hardness as compared to TS. Hence, TS can be used as alternative for fine aggregate in sustainable construction. Full article
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Article
Cleaner Approach for Atrazine Removal Using Recycling Biowaste/Waste in Permeable Barriers
Recycling 2021, 6(2), 41; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020041 - 17 Jun 2021
Viewed by 698
Abstract
This work addresses the rehabilitation of water contaminated with atrazine, entrapping it in a permeable and sustainable barrier designed with waste materials (sepiolite) and with biomaterials (cork and pine bark). Atrazine adsorption was assessed by kinetics and equilibrium assays and desorption was tested [...] Read more.
This work addresses the rehabilitation of water contaminated with atrazine, entrapping it in a permeable and sustainable barrier designed with waste materials (sepiolite) and with biomaterials (cork and pine bark). Atrazine adsorption was assessed by kinetics and equilibrium assays and desorption was tested with different extraction solvents. Adsorbed atrazine was 100% recovered from sepiolite using 20% acetonitrile solution, while 40% acetonitrile was needed to leach it from cork (98%) and pine bark (94%). Continuous fixed-bed experiments using those sorbents as PRB were performed to evaluate atrazine removal for up-scale applications. The modified dose-response model properly described the breakthrough data. The highest adsorption capacity was achieved by sepiolite (23.3 (±0.8) mg/g), followed by pine bark (14.8 (±0.6) mg/g) and cork (13.0 (±0.9) mg/g). Recyclability of sorbents was evaluated by adsorption-desorption cycles. After two regenerations, sepiolite achieved 81% of atrazine removal, followed by pine with 78% and cork with 54%. Sepiolite had the best performance in terms of adsorption capacity/stability. SEM and FTIR analyses confirmed no significant differences in material morphology and structure. This study demonstrates that recycling waste/biowaste is a sustainable option for wastewater treatment, with waste valorization and environmental protection. Full article
(This article belongs to the Special Issue Reuse of Wastewater: Recovery of Water, Nutrients, and Energy)
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Article
Fungi and Circular Economy: Pleurotus ostreatus Grown on a Substrate with Agricultural Waste of Lavender, and Its Promising Biochemical Profile
Recycling 2021, 6(2), 40; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020040 - 11 Jun 2021
Viewed by 681
Abstract
The increasing production of essential oils has generated a significant amount of vegetal waste that must be discarded, increasing costs for farmers. In this context, fungi, due to their ability to recycle lignocellulosic matter, may be used to turn this waste into new [...] Read more.
The increasing production of essential oils has generated a significant amount of vegetal waste that must be discarded, increasing costs for farmers. In this context, fungi, due to their ability to recycle lignocellulosic matter, may be used to turn this waste into new products, thus generating additional income for essential oil producers. The objectives of our work, within the framework of the European ALCOTRA project FINNOVER, were two-fold. The first was to cultivate Pleurotus ostreatus on solid waste of lavender used for essential oil production. The second was to provide, at the same time, new products that can increase the income of small and medium farms in the Ligurian Italian Riviera. This paper presents two pilot tests in which P. ostreatus was grown on substrates with five different concentrations of lavender waste, ranging from 0 to 100% (w/w). Basidiomata grown on all the substrates and their biochemical profiles were characterized using high-performance liquid chromatography coupled to mass spectrometry. The biochemical analysis of mushrooms proved the presence of molecules with antioxidant and potential pharmacological properties, in particular in mushrooms grown on lavender-enriched substrates. The results open the possibility of producing mushrooms classified as a novel food. Furthermore, the results encourage further experiments aimed at investigating how different substrates positively affect the metabolomics of mushrooms. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Article
Appraisal of Households’ Knowledge and Perception towards E-Waste Management in Limpopo Province, South Africa
Recycling 2021, 6(2), 39; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020039 - 11 Jun 2021
Viewed by 685
Abstract
The generation of electronic waste (e-waste) is increasing at an alarming rate in South Africa. This waste stream is also emanating from household appliances due to beneficial attributes accrued to the use of these electronic devices. At the same time, these devices are [...] Read more.
The generation of electronic waste (e-waste) is increasing at an alarming rate in South Africa. This waste stream is also emanating from household appliances due to beneficial attributes accrued to the use of these electronic devices. At the same time, these devices are a source of concern considering the environmental impacts as well the threat of health hazards they possess to human wellbeing. In appraising household knowledge and perception on e-waste management in Limpopo Province of South Africa, 200 semi-structured, self-administered questionnaires were used in eliciting data from the participants. The results indicated that 76% of the respondents believed that e-waste streams have negatively affected their environment. Additionally, 85% of the survey households are willing to pay for the proper disposal of their e-waste. Furthermore, the results indicated a statistically significance between gender and knowledge on e-waste management (p-value 0.003) while there was no statistically significant difference between gender and perception (p-value 0.318) on e-waste management. Based on the results, the study recommends awareness and educational campaigns as a step in changing the perception of households on e-waste and environmental consciousness. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Review
Extraction of Valuable Elements from Red Mud with a Focus on Using Liquid Media—A Review
Recycling 2021, 6(2), 38; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020038 - 10 Jun 2021
Cited by 2 | Viewed by 945
Abstract
Bauxite residue, known as red mud, is a by-product of alumina production using the Bayer process. Currently, its total global storage amounts to over 4.6 billion tons, including about 600 million tons in Russia. The total global storage of red mud occupies large [...] Read more.
Bauxite residue, known as red mud, is a by-product of alumina production using the Bayer process. Currently, its total global storage amounts to over 4.6 billion tons, including about 600 million tons in Russia. The total global storage of red mud occupies large areas, leading to environmental damage and increasing environmental risks. Moreover, it contains a significant amount of sodium, which is easily soluble in subsoil water; therefore, a sustainable approach for comprehensive recycling of red mud is necessary. The bauxite residue contains valuable elements, such as aluminum, titanium, and scandium, which can be recovered using liquid media. In recent years, many methods of recovery of these elements from this waste have been proposed. This paper provides a critical review of hydrometallurgical, solvometallurgical, and complex methods for the recovery of valuable components from red mud, namely, aluminum, titanium, sodium, and rare and rare-earth elements. These methods include leaching using alkaline or acid solutions, ionic liquids, and biological organisms, in addition to red mud leaching solutions by extraction and sorption methods. Advantages and disadvantages of these processes in terms of their environmental impact are discussed. Full article
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Article
Physical and Mechanical Properties of Sustainable Hydraulic Mortar Based on Marble Slurry with Waste Glass
Recycling 2021, 6(2), 37; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020037 - 09 Jun 2021
Viewed by 694
Abstract
This paper aims to propose and characterize a sustainable hydraulic mortar entirely obtained by the reuse of waste materials, with marble slurry coming from quarries in the north-western Sicily and glass powder coming from a waste collection plant in Marsala (Province of Trapani). [...] Read more.
This paper aims to propose and characterize a sustainable hydraulic mortar entirely obtained by the reuse of waste materials, with marble slurry coming from quarries in the north-western Sicily and glass powder coming from a waste collection plant in Marsala (Province of Trapani). The first was used as raw material to produce the mortar binder by a kilning and slaking process, while the second was used as a pozzolanic additive. The chemical and morphological characterization of the marble slurry was done by XRD, FTIR, STA and SEM analyses. Glass powder was analyzed through particle size distribution measurements, XRD and standard pozzolanic tests. Hydraulic mortars constituted by slaked lime from kilned marble slurry and waste glass powder (LGS) were prepared beside commercial Natural Hydraulic Lime (NHL) based mortars (NGS) and air-hardening lime (LSS)-based mortars. Mechanical and absorption properties of the mortars were investigated as a function of the grain size of the glass powder by means of three-point bending and compressive strength tests, capillary uptake, helium pycnometry and simultaneous thermal analysis. The results demonstrated that the formulation LGS exhibits significantly improved mechanical and absorption properties compared to air-hardening mortars (LSS). It confirms the possibility of producing a more sustainable hydraulic mortar exclusively from waste materials for civil engineering. Full article
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Article
Characterization of Cytisus striatus (Hill) Rothm.: Waste Biomass Energy Recovery as a Measure to Reduce the Risk of Rural Fires
Recycling 2021, 6(2), 36; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020036 - 07 Jun 2021
Viewed by 745
Abstract
Shrub species play a critical ecological role in ecosystems, covering significant areas. However, with the current development of vegetation cover, conditioned by climate change, certain species have acquired a dominant role, which suffocates the other ecosystem species in a natural monoculture model. Thus, [...] Read more.
Shrub species play a critical ecological role in ecosystems, covering significant areas. However, with the current development of vegetation cover, conditioned by climate change, certain species have acquired a dominant role, which suffocates the other ecosystem species in a natural monoculture model. Thus, some species, such as Cytisus striatus (Hill) Rothm., have acquired preponderance, mainly due to the dense forests they establish. This situation has contributed to the increased risk of rural fires, forcing permanent actions to control the settlements. These actions entail costs that make the continuity and permanence of control unsustainable. The energetic valorization of residual biomass resulting from operations to reduce fuel load is an option that seems viable, mainly if used in the production of biomass pellets in a mixture with other biomasses, such as Pinus pinaster or Eucalyptus globulus. The laboratory characterization tests demonstrated that the residual biomass of C. striatus presents parameters that fall within limits defined by the standard ENPlus®. The processing of this residual biomass on an industrial scale line is also feasible. However, given the configuration of the material to be processed, production lines may be necessary, especially concerning the detachment of the material. The logistical issue may also impose restrictions since the material has a low density, even when baled. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Review
The Necessity of Recycling of Waste Li-Ion Batteries Used in Electric Vehicles as Objects Posing a Threat to Human Health and the Environment
Recycling 2021, 6(2), 35; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020035 - 01 Jun 2021
Viewed by 965
Abstract
The automotive industry is one of the fastest-growing sectors of the modern economy. Growing customer expectations, implementing solutions related to electromobility, and increasingly stringent legal restrictions in the field of environmental protection, determine the development and introduction of innovative technologies in the field [...] Read more.
The automotive industry is one of the fastest-growing sectors of the modern economy. Growing customer expectations, implementing solutions related to electromobility, and increasingly stringent legal restrictions in the field of environmental protection, determine the development and introduction of innovative technologies in the field of car production. To power the most modern vehicles that include electric and hybrid cars, packages of various types of lithium-ion cells are used, the number of which is constantly growing. After use, these batteries, due to their complex chemical composition, constitute hazardous waste that is difficult to manage and must be recycled in modern technological lines. The article presents the morphological characteristics of the currently used types of Li-ion cells, and the threats to the safety of people and the environment that may occur in the event of improper use of Li-ion batteries and accumulators have been identified and described on the basis of the Regulation of the European Parliament and Council (EC) No. 1272/2008 of 16 December 2008 and No. 1907/2006 of 18 December 2006 on the classification, labeling and packaging of substances and mixtures and the registration, evaluation, authorization and restriction of chemicals (REACH), establishing the European Chemicals Agency. Full article
Review
A Systematic Review of Construction and Demolition Waste Management in Australia: Current Practices and Challenges
Recycling 2021, 6(2), 34; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020034 - 21 May 2021
Cited by 3 | Viewed by 978
Abstract
Construction and demolition waste (C&DW) has a deleterious impacts on sustainability not only in developing countries but also in developed nations. For example, Australia generated more than 27 million tonnes of C&DW in 2018–2019; however, only 60% of this waste stream was recovered. [...] Read more.
Construction and demolition waste (C&DW) has a deleterious impacts on sustainability not only in developing countries but also in developed nations. For example, Australia generated more than 27 million tonnes of C&DW in 2018–2019; however, only 60% of this waste stream was recovered. Considering this low recovery rate, lower than many developed nations, and with regards to the increasing rate of C&DW generation, extra attention should be given to the construction and demolition waste management (C&DWM) in Australia. Therefore, this research attempts to accurately understand the current practices and challenges of C&DWM in Australia. To do so, primarily, a systematic review of studies relevant to C&DWM from 2010 to 2021 was performed. In this step, 26 research documents were meticulously analysed to identify the current practices of C&DWM in Australia. Then, an in-depth interview with three experts were undertaken to verify the major results and to investigate the challenges of C&DWM in Australia. The results indicated that three factors significantly affect C&DWM in Australia, namely attitudes and behaviour of C&DWM stakeholders, C&DWM in project life cycles, and C&DWM regulations with regards to sustainability, adding that the latter was revealed as the most effective in C&DWM in Australia. Full article
(This article belongs to the Special Issue Using Circular Economy Principles to Manage Construction Waste)
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Article
Recycling Potential for Non-Valorized Plastic Fractions from Electrical and Electronic Waste
Recycling 2021, 6(2), 33; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020033 - 19 May 2021
Cited by 1 | Viewed by 886
Abstract
This paper describes a study for waste of electrical and electronic equipment (WEEE) to characterise the plastic composition of different mixed plastic fractions. Most of the samples studied are currently excluded from material recycling and arise as side streams in state-of-the-art plastics recycling [...] Read more.
This paper describes a study for waste of electrical and electronic equipment (WEEE) to characterise the plastic composition of different mixed plastic fractions. Most of the samples studied are currently excluded from material recycling and arise as side streams in state-of-the-art plastics recycling plants. These samples contain brominated flame retardants (BFR) or other substances of concern listed as persistent organic pollutants or in the RoHS directive. Seventeen samples, including cathode ray tube (CRT) monitors, CRT televisions, flat screens such as liquid crystal displays, small domestic appliances, and information and communication technology, were investigated using density- and dissolution-based separation processes. The total bromine and chlorine contents of the samples were determined by X-ray fluorescence spectroscopy, indicating a substantial concentration of both elements in density fractions above 1.1 g/cm3, most significantly in specific solubility classes referring to ABS and PS. This was further supported by specific flame retardant analysis. It was shown that BFR levels of both polymers can be reduced to levels below 1000 ppm by dissolution and precipitation processes enabling material recycling in compliance with current legislation. As additional target polymers PC and PC-ABS were also recycled by dissolution but did not require an elimination of BFR. Finally, physicochemical investigations of recycled materials as gel permeation chromatography, melt flow rate, and differential scanning calorimetry suggest a high purity and indicate no degradation of the technical properties of the recycled polymers. Full article
(This article belongs to the Special Issue Polymer Recycling)
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Article
Performance Assessment of Reclaimed Asphalt Pavement (RAP) in Road Surface Mixtures
Recycling 2021, 6(2), 32; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020032 - 13 May 2021
Cited by 2 | Viewed by 795
Abstract
Considerable amounts of Reclaimed Asphalt Pavement (RAP) are produced every year, as the road network requires maintenance to ensure the safety and comfort of its users. RAP is a 100% recyclable material and a useful fit to be re-introduced into another cycle without [...] Read more.
Considerable amounts of Reclaimed Asphalt Pavement (RAP) are produced every year, as the road network requires maintenance to ensure the safety and comfort of its users. RAP is a 100% recyclable material and a useful fit to be re-introduced into another cycle without downgrading its functionality. Despite the current knowledge about the benefits associated with RAP use, it is not yet largely applied in several countries. This paper aims to validate, on the basis of both short- and long-term mechanical behaviours, the application of a bituminous mixture with a high RAP incorporation rate (75%) in road pavement wearing courses. A crude tall oil rejuvenator was used. Both short- and long-term oven ageing procedures were employed to simulate the ageing that occurs during mixture production and in-service life, respectively. The tests for validating the RAP mixture as an alternative solution comprised stiffness, resistance to fatigue, permanent deformation, and determination of the water sensitivity. Furthermore, the RAP bitumen mobilisation degree was evaluated and a mixing protocol was established. In comparison with virgin bituminous mixtures, it was found that, in general, the high RAP mixtures presented similar or better behaviour. The ageing process had a hardening effect namely in terms of stiffness and resistance to permanent deformation, without significant effects on the resistance to fatigue and water damage. Full article
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Article
Direct Recycling R&D at the ReCell Center
Recycling 2021, 6(2), 31; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020031 - 13 May 2021
Viewed by 1384
Abstract
The expected rapid growth in electric vehicle deployment will inevitably be followed by a corresponding rise in the supply of end-of-life vehicles and their lithium-ion batteries (LIBs). The batteries may be reused, but will eventually be spent and provide a potential domestic resource [...] Read more.
The expected rapid growth in electric vehicle deployment will inevitably be followed by a corresponding rise in the supply of end-of-life vehicles and their lithium-ion batteries (LIBs). The batteries may be reused, but will eventually be spent and provide a potential domestic resource that can help supply materials for future battery production. However, commercial recycling processes depend on profits from recovery of cobalt, use of which is being reduced in new cathode chemistries. The U.S. Department of Energy, therefore, established the ReCell Center in early 2019 to develop robust LIB recycling technology that would be economical even for batteries that contain no cobalt. The central feature of the technology is recovery of the cathode material with its unique crystalline cathode morphology intact in order to retain its value and functionality. Other materials are recovered as well in order to maximize revenues and minimize waste-handling costs. Analysis and modeling serve to evaluate and compare process options so that we can identify those that will be most economical while still minimizing energy use and environmental impacts. This paper provides background and describes highlights of the center’s first 2 years of operation. Full article
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Review
Factors Affecting Mobile Waste Recycling through RSCM: A Literature Review
Recycling 2021, 6(2), 30; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020030 - 08 May 2021
Viewed by 917
Abstract
Mobile phone consumers have been motivated by the rapid growth of technology and encouraged to update their devices regularly to keep up with new innovations, architectures, and capabilities. Consequently, mobile/cell phone waste has risen significantly in the last decade. Due to their small [...] Read more.
Mobile phone consumers have been motivated by the rapid growth of technology and encouraged to update their devices regularly to keep up with new innovations, architectures, and capabilities. Consequently, mobile/cell phone waste has risen significantly in the last decade. Due to their small size, it is convenient for users to keep outdated or unused mobile phones at home or the office, rather than recycling them appropriately. A reverse supply chain (RSC) is one possible method of mitigating the questionable e-waste activity present in the ecosystem. RSC has been significant for the mobile phone industry, user states, analysts, and scholars. This paper reviews the available literature in the RSC management (RSCM) domain, along with its processes and strategies. The paper reviews 223 published scholarly papers in the domain of mobile phone waste recycling and investigates 22 papers related to factors influencing consumers’ intention with regard to electronic recycling, focusing on mobile devices, which contribute significantly to electronic waste management practices. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Article
Incentives for Plastic Recycling: How to Engage Citizens in Active Collection. Empirical Evidence from Spain
Recycling 2021, 6(2), 29; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020029 - 26 Apr 2021
Cited by 2 | Viewed by 989
Abstract
The recycling target for plastics is expected to increase Europe-wide from 22.5% to 55% by 2025, hence the relevance of incentive schemes and the need to reach conclusions about how to encourage families to recycle more. Following this objective, a pilot project was [...] Read more.
The recycling target for plastics is expected to increase Europe-wide from 22.5% to 55% by 2025, hence the relevance of incentive schemes and the need to reach conclusions about how to encourage families to recycle more. Following this objective, a pilot project was implemented and a virtual reward token called RECICLOS created to encourage recycling among families, using incentives and awards to improve recycling behaviour and a webapp prototype to register the recycled plastic. By the end of the 6-week pilot project, 1053 families were registered on the scheme, representing 10% of the targeted population in the pilot area of the county of Pla de l’Estany, Catalonia, Spain. The novelties were the introduction of a token, the gamification of incentives through raffles and lotteries, webapp-based direct communication with citizens, and feedback after collecting and registering the recycled material. The multidimensional aspects of recycling activities, their strong relation with human behavioural patterns, and the high demand for communication and interaction mean that mobile technologies find significant application in this field. The results show that people can be influenced and their recycling habits changed by means of varied, effective, and innovative incentive schemes. Full article
(This article belongs to the Special Issue Advances in the Recycling and Processing of Plastic Waste)
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Article
Energy Recovery of Agricultural Residues: Incorporation of Vine Pruning in the Production of Biomass Pellets with ENplus® Certification
Recycling 2021, 6(2), 28; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020028 - 22 Apr 2021
Cited by 2 | Viewed by 779
Abstract
The use of residual biomass of forest and/or agricultural origin is an increasingly common issue regarding the incorporation of materials that, until recently, were out of the typical raw material supply chains for the production of biomass pellets, mainly due to the quality [...] Read more.
The use of residual biomass of forest and/or agricultural origin is an increasingly common issue regarding the incorporation of materials that, until recently, were out of the typical raw material supply chains for the production of biomass pellets, mainly due to the quality constraints that some of these materials present. The need to control the quality of biomass-derived fuels led to the development of standards, such as ENplus®, to define the permitted limits for a set of parameters, such as the ash or alkali metal content. In the present study, samples of vine pruning, and ENplus®-certified pellets were collected and characterized, and the results obtained were compared with the limits presented in the standard. The values presented from vine pruning approximated the values presented by Pinus pinaster wood, the main raw material used in the production of certified pellets in Portugal, except for the values of ash, copper (Cu), and nitrogen (N) contents, with vine pruning being out of the qualifying limits for certification. However, it was found that the incorporation of up to 10% of biomass from vine pruning allowed the fulfillment of the requirements presented in the ENplus® standard, indicating a path for the implementation of circular economy processes in the wine industry. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials)
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Article
Recovery of Platinum from a Spent Automotive Catalyst through Chloride Leaching and Solvent Extraction
Recycling 2021, 6(2), 27; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020027 - 17 Apr 2021
Viewed by 986
Abstract
Considering economics and environmental sustainability, recycling of critical metals from end-of-life devices should be a priority. In this work the hydrometallurgical treatment of a spent automotive catalytic converter (SACC) using HCl with CaCl2 as a leaching medium, and solvent extraction (SX) with [...] Read more.
Considering economics and environmental sustainability, recycling of critical metals from end-of-life devices should be a priority. In this work the hydrometallurgical treatment of a spent automotive catalytic converter (SACC) using HCl with CaCl2 as a leaching medium, and solvent extraction (SX) with a thiodiglycolamide derivative, is reported. The aim was to develop a leaching scheme allowing high Pt recoveries and minimizing Al dissolution, facilitating the application of SX. The replacement of part of HCl by CaCl2 in the leaching step is viable, without compromising Pt recovery (in the range 75–85%), as found for the mixture 2 M CaCl2 + 8 M HCl when compared to 11.6 M HCl. All leaching media showed good potential to recover Ce, particularly for higher reaction times and temperatures. Regarding SX, results achieved with a model solution were promising, but SX for Pt separation from the real SACC solution did not work as expected. For the adopted experimental conditions, the tested thiodiglycolamide derivative in toluene revealed a very good loading performance for both Pt and Fe, but Fe removal and Pt stripping from the organic phases after contact with the SACC solution were not successfully accomplished. Hence, the reutilization of the organic solvent needs improvement. Full article
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Article
The Recycling of Waste Laminated Glass through Decomposition Technologies
Recycling 2021, 6(2), 26; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020026 - 15 Apr 2021
Viewed by 868
Abstract
Laminated glass is ever more frequently used nowadays. This applies to the automobile industry and the construction industry. In cars, this refers mostly to the front and rear windows, whereas in construction, technical safety glass is used for railings and window glass. The [...] Read more.
Laminated glass is ever more frequently used nowadays. This applies to the automobile industry and the construction industry. In cars, this refers mostly to the front and rear windows, whereas in construction, technical safety glass is used for railings and window glass. The task of this type of glass is to provide sufficient resistance against mechanical impact and unpleasant weather conditions. At the same time, if it is damaged, it has to break into the smallest possible pieces, or, wherever possible, the glass should remain intact on the interlayer film to prevent shards from injuring people and animals in the immediate vicinity. The paper deals with the recycling of laminated glass, especially with the effective separation of glass (in the form of cullet) from the polyvinyl butyral (PVB) interlayer film. The experimental research is focused on the mechanical separation of glass from the interlayer film by vibration, and also on the chemical cleaning of PVB film in order to allow subsequent recycling of both materials. The results quantify the efficiency of mechanical separation in the form of weight loss of the sample of laminated glass and define the particle size distribution of glass cullet, which is an important parameter in the possibility of glass recycling. The research leads to a methodology proposal for the separation of glass and PVB film and the design of equipment for this method. Full article
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Article
Phosphorus Recovery from Wastewater: Bioavailability of P Bound to Calcareous Material for Maize (Zea Mays L.) Growth
Recycling 2021, 6(2), 25; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020025 - 13 Apr 2021
Viewed by 1019
Abstract
(1) Phosphorus (P) is an essential plant nutrient, and P deficiency negatively affects plant growth and development. Furthermore, P is a finite and nonrenewable resource, and there is an urgent need to recover P from some of the important waste streams in society. [...] Read more.
(1) Phosphorus (P) is an essential plant nutrient, and P deficiency negatively affects plant growth and development. Furthermore, P is a finite and nonrenewable resource, and there is an urgent need to recover P from some of the important waste streams in society. Newly engineered calcareous materials (sol–gel coated cat litter (CATSAN®)) can bind P from wastewater in decentralized treatment systems and potentially enable P recycling into agricultural production by direct addition of the P saturated material. (2) The effects of the addition of two P-enriched calcareous materials as fertilizers for maize (Zea mays L.) growth were investigated in a mesocosm experiment. We compared fertilization with the P-enriched materials at rates of 6, 12, 25, 50, 100 kg P ha−1 yr−1 with fertilization with commercial NPK fertilizer. (3) The P fertilization by the P-enriched materials had a significant positive effect on plant height, biomass, maximum light-saturated photosynthetic rate, respiration rate, and total P content in biomass. However, plants fertilized by the commercial NPK fertilizer performed significantly better in the majority of measured parameters at identical fertilization rates. (4) The bioavailability of the P bound to the calcareous material was very low. However, the studied material has the potential to be used as part of a decentralized treatment solution to remove and subsequently recover and recycle P from wastewater. Full article
(This article belongs to the Special Issue Reuse of Wastewater: Recovery of Water, Nutrients, and Energy)
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Article
Moderating Effects on Residents’ Willingness in Waste Sorting to Improve Waste Handling in Dammam City, Saudi Arabia
Recycling 2021, 6(2), 24; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020024 - 06 Apr 2021
Cited by 1 | Viewed by 961
Abstract
While the total amount of municipal solid waste (MSW) in Dammam city was about 13 million tons in 2013, it is expected to reach about 18.4 million tons in 2025. Although the main problem in Dammam city is an increase in solid waste [...] Read more.
While the total amount of municipal solid waste (MSW) in Dammam city was about 13 million tons in 2013, it is expected to reach about 18.4 million tons in 2025. Although the main problem in Dammam city is an increase in solid waste production without any formal treatment except landfilling, the lack of waste segregation greatly affects the residents’ handling practices of solid waste due to incorrect disposing practices. The objective of this study explored the possibility of Dammam residents’ participation in sorting and recycling to improve MSW handling and to measure the influence of psychological factors which affecting residents’ willingness to participate in waste handling regarding socioeconomic levels and moderating effects. This study also examined various respondents’ perspectives on sorting and recycling sustainable waste and the handling of waste generation. This study covered most Dammam communities, with a gender distribution of 56% males and 44% females and the monthly income ranging from SR700 to SR12,000. The descriptive analysis showed that of the 450 participants, 170 (37.8%) were in the middle-income levels, 199 (44.2%) were in the high-income levels and 81 (18%) were in the low-income levels. The moderating effect of income was observed between attitude and willingness to sort and recycle waste in the low-income levels and high-income levels groups. Additionally, an association was found between market incentives and willingness to sort and recycle waste in the low-income levels and high-income levels groups. The gender status of the participants had a moderating effect on the relationship between market incentives and willingness to sort and recycle waste in males and females. Additionally, the moderating effect of social influence on households’ willingness to sort and recycle waste was moderated by gender in males and females. Full article
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Article
Mechanical Properties of Concrete with Recycled Concrete Aggregate and Fly Ash
Recycling 2021, 6(2), 23; https://0-doi-org.brum.beds.ac.uk/10.3390/recycling6020023 - 01 Apr 2021
Cited by 1 | Viewed by 806
Abstract
Recycled concrete aggregate (RCA) collected from the demolition of old reinforced concrete structures can be reused to prepare structural and non-structural concrete, thereby protecting the environment by preserving natural resources. This study explores RCA’s use, collected from the crushed concrete of different building [...] Read more.
Recycled concrete aggregate (RCA) collected from the demolition of old reinforced concrete structures can be reused to prepare structural and non-structural concrete, thereby protecting the environment by preserving natural resources. This study explores RCA’s use, collected from the crushed concrete of different building projects in Riyadh, to manufacture fresh self-compacting concrete (SCC) and investigate its properties in the fresh and hardened state. Four SCC mixes were prepared by replacing natural aggregate (NA) with RCA at 0%, 25%, 50%, and 75% replacement levels. The water-cement (w/c) ratio was maintained constant at 0.38 for all the mixes. Slump Flow, J-ring, and V-funnel tests were performed on the SCC mixes in the fresh state, and the compressive strength of hardened concrete was determined after seven, 14, and 28 days. Water absorption and split tensile tests were also carried out for all the mixes. The findings revealed that it is possible to reach compressive strengths higher than 40 MPa at 28 days for RCA replacement level of 75% by using a superplasticizer and low w/c ratio. The decrease in compressive strength concerning the SCC-NA mix was 25% for 75% replacement level. The highest split tensile strength at 28 days was around 3.3 MPa for a 50% replacement level. The lowest water absorption was 3.2% for SCC-NA, which was gradually increased and was highest at 5.6% for 75% replacement level. Full article
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