Recycling

21 pages, 2050 KiB

Open AccessArticle

Improving the Decision-Making for Sustainable Demolition Waste Management by Combining a Building Information Modelling-Based Life Cycle Sustainability Assessment Framework and Hybrid Multi-Criteria Decision-Aiding Approach

by Dongchen Han and Abbas Rajabifard

Recycling 2024, 9(4), 70; https://doi.org/10.3390/recycling9040070 - 20 Aug 2024

Viewed by 1532

Abstract

Increasing efforts have been devoted to promoting sustainable demolition waste management (DWM) from a life cycle thinking perspective. To this end, facilitating sustainability-oriented decision-making for DWM planning requires a sustainability assessment framework for assessing the trade-offs among multifaceted criteria. This study develops a [...] Read more.

Increasing efforts have been devoted to promoting sustainable demolition waste management (DWM) from a life cycle thinking perspective. To this end, facilitating sustainability-oriented decision-making for DWM planning requires a sustainability assessment framework for assessing the trade-offs among multifaceted criteria. This study develops a BIM-based DWM sustainability assessment approach to facilitate the life cycle sustainability assessment (LCSA) and decision-making by integrating LCSA-related properties and hybrid Multi-Criteria Decision-Aiding (MCDA) methods into a BIM environment using Dynamo visual scripting. A dynamic linkage is developed in the streamlined BIM-based LCSA process, where the enriched Industry Foundation Class (IFC) models are coupled with custom LCSA data templates to achieve seamless data exchange between the BIM platform and external LCA tools. Subsequently, hybrid MCDA methods convert the assessment results into DWM scenario ranking. A pilot study verifies the applicability of the BIM-based framework. The results unveil that the sustainability score ascended with the recycling rate. The optimal DWM alternative with the highest recycling rate yields the highest sustainability score at 91.63. Conversely, a DWM alternative reflecting the ‘status quo’ in China’s recycling industry has the lowest score at 8.37, significantly lower than the baseline scenario with a 50% recycling rate. It is worth noting that the ‘growth curve’ of the sustainability score continuously flattens as the target recycling rate escalates. The increment in recycling rate from the “Australian standard” scenario to the optimal scenario is 18.4%, whereas the sustainability score merely increases by 2.3%, implying that the former scenario arrived at an optimum point for maximising the cost-efficiency of DWM under the predefined settings. Full article

(This article belongs to the Topic Circular Economy Innovations and Breakthroughs for Built Environments)

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20 pages, 1705 KiB

Open AccessReview

Green Roof Systems within the Framework of a Circular Economy: A Scoping Review

by Ana Laura Cervantes-Nájera, María-Concepción Martínez-Rodríguez, Lorena Elizabeth Campos-Villegas, Xochitl Virginia Bello-Yañez and Stephan Brenneisen

Recycling 2024, 9(4), 69; https://doi.org/10.3390/recycling9040069 - 19 Aug 2024

Viewed by 2767

Abstract

Green roofs are nature-based solutions with multiple benefits for the urban environment, but they have specific polymeric components in their structure that cause a carbon footprint. This scoping review highlights the technological advance in reusing or recycling alternative materials in green roof structures [...] Read more.

Green roofs are nature-based solutions with multiple benefits for the urban environment, but they have specific polymeric components in their structure that cause a carbon footprint. This scoping review highlights the technological advance in reusing or recycling alternative materials in green roof structures worldwide, making them a part of the circular economy (CE), and the search strategies to promote them to find whether there is a relation between them. The data were collected using the Web of Science from 2012 to 2022; we also used the Bibliometrix package to analyse research development by country and the development of the topic by author’s keywords. We selected 68 open-access articles from twenty-four countries and reviewed the grey literature from the top five productive countries on this topic. Our findings show that CE strategies are performed nationally, while the green roof promotion ones are concentrated at the city level. The theme co-occurrence analysis showed that the substrate is the primary layer used with alternative materials, and the three materials most applied for it are rubber, biochar, and hydrogel. It was found that the primary purpose of optimising green roofs with alternative materials is to increase the ecosystem services they provide and indirectly function within the circular economy; still, there is a gap in estimating the environmental impact of doing this as a potential CE activity. Full article

(This article belongs to the Special Issue Sustainability of the Circular Economy)

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Graphical abstract

12 pages, 2713 KiB

Open AccessCommunication

A Business Model for Circular Bioeconomy: Edible Mushroom Production and Its Alignment with the Sustainable Development Goals (SDGs)

by Viviany Viriato, Silvia Angélica Domingues de Carvalho, Bruno de Lima Santoro and Filipe Pereira Giardini Bonfim

Recycling 2024, 9(4), 68; https://doi.org/10.3390/recycling9040068 - 15 Aug 2024

Cited by 1 | Viewed by 2182

Abstract

Agricultural wastes (AWs) generated from farming practices pose environmental threats if not properly disposed of or recycled through biological processes. Mushroom production presents a sustainable solution by converting AWs into highly nutritious food while mitigating environmental pollution. However, there is a lack of [...] Read more.

Agricultural wastes (AWs) generated from farming practices pose environmental threats if not properly disposed of or recycled through biological processes. Mushroom production presents a sustainable solution by converting AWs into highly nutritious food while mitigating environmental pollution. However, there is a lack of comprehensive frameworks to assist farmers and businesses in visually understanding the essential elements of a circular bioeconomy, such as mushroom production’s potential interconnections and impacts on value creation. This study theoretically elaborates on a framework using the Business Model Canvas to structure mushroom production across the following key business areas: customers, supply chains, infrastructure, and economic viability. We discuss these aspects within the context of recent studies. In addition to guiding farmers and businesses, we align mushroom production with Sustainable Development Goals (SDGs) within the supply chain, underscoring the importance of developing business models to foster the growth of circular economies and sustainability. Full article

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11 pages, 2180 KiB

Open AccessArticle

Quality-Driven Allocation Method to Promote the Circular Economy for Plastic Components in the Automotive Industry

by Ilka Pfisterer, Roman Rinberg, Lothar Kroll and Niels Modler

Recycling 2024, 9(4), 67; https://doi.org/10.3390/recycling9040067 - 9 Aug 2024

Viewed by 1369

Abstract

In recent years, the development of a circular economy of plastic products in the automotive industry has been pursued by original equipment manufacturers (OEMs) not only due to strategic premises by the European Commission but also due to an increasing demand by customers. [...] Read more.

In recent years, the development of a circular economy of plastic products in the automotive industry has been pursued by original equipment manufacturers (OEMs) not only due to strategic premises by the European Commission but also due to an increasing demand by customers. To achieve a circular economy, high-quality recyclates are needed. However, in the current situation, there is a discrepancy between the low-quality recyclate that is available on the market and the high-quality recyclate that is demanded by manufacturers. To increase the quality of recyclate on the market, a standardized process to reward a ‘design-for-recycling’ approach at the product development stage is needed. This paper proposes an allocation method that takes into account material compositions and common recycling processes and incentivizes the preservation of high-quality grades of recyclate based on grade purity. Full article

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15 pages, 6308 KiB

Open AccessArticle

Silicon Kerf Recovery via Acid Leaching Followed by Melting at Elevated Temperatures

by Tinotenda Mubaiwa, Askh Garshol, Alexander Azarov and Jafar Safarian

Recycling 2024, 9(4), 66; https://doi.org/10.3390/recycling9040066 - 8 Aug 2024

Viewed by 1126

Abstract

The aim of this work was to study the purification of silicon kerf loss waste (KLW) by a combination of single-acid leaching followed by inductive melting at high temperatures with an addition of fluidized bed reactor (FBR) silicon granules. The KLW indicated an [...] Read more.

The aim of this work was to study the purification of silicon kerf loss waste (KLW) by a combination of single-acid leaching followed by inductive melting at high temperatures with an addition of fluidized bed reactor (FBR) silicon granules. The KLW indicated an average particle size (D50) of approximately 1.6 µm, and a BET surface area of 30.4 m²/g. Acid leaching by 1 M HCl indicated significant removal of impurities such as Ni (77%), Fe (91%) and P (75%). The combined two-stage treatment resulted in significant removal of the major impurities: Al (78%), Ni (79%), Ca (85%), P (92%) and Fe (99%). The general material loss during melting decreased with an increasing amount of FBR silicon granules which aided in the melting process and indicated better melting. It was observed that the melting behavior of the samples improved as the temperature increased, with complete melting being observed throughout the crucibles at the highest temperature (1800 °C) used, even without any additives. At lower temperatures (1600 °C–1700 °C) and lower FBR-Si (<30 wt.%) additions, the melting was incomplete, with patches of molten silicon and a lot of surface oxidation as confirmed by both visual observation and electron microscopy. In addition, it was indicated that more reactive and volatile elements (Ga, Mg and P) compared to silicon are partially removed in the melting process (51–87%), while the less reactive elements end up in the final silicon melt. It was concluded that if optimized, the combined treatment of single-acid leaching and inductive melting with the addition of granular FBR silicon has great potential for the recycling of KLW to solar cells and similar applications. Moreover, the application of higher melting temperatures is accompanied by a higher silicon yield of the process, and the involved mechanisms are presented. Full article

(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)

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12 pages, 936 KiB

Open AccessArticle

Production of Volatile Fatty Acids from Cheese Whey and Their Recovery Using Gas-Permeable Membranes

by Beatriz Molinuevo-Salces, Viviane da Silva-Lacerda, María Cruz García-González and Berta Riaño

Recycling 2024, 9(4), 65; https://doi.org/10.3390/recycling9040065 - 5 Aug 2024

Viewed by 1043

Abstract

The use of anaerobic fermentation to produce volatile fatty acids (VFAs) is an environmentally sustainable alternative for cheese whey (CW) valorization. This study evaluates the effect of pH control on the conversion of organic matter to VFAs from CW and assesses VFA recovery [...] Read more.

The use of anaerobic fermentation to produce volatile fatty acids (VFAs) is an environmentally sustainable alternative for cheese whey (CW) valorization. This study evaluates the effect of pH control on the conversion of organic matter to VFAs from CW and assesses VFA recovery using a novel approach based on gas-permeable membranes. VFA bioconversion and composition were studied with initial and sequential control of pH, both in acidic and alkaline conditions. Bioconversion efficiencies for assays with initial pH control were 36% and 45% for acidic and alkaline conditions, respectively. Sequential control of pH resulted in an increase in bioconversion to 54% under acidic conditions. Under acidic conditions, a variety of VFA was produced (mainly butyric, acetic, and propionic acids), while under alkaline conditions the majority was acetic acid. VFA recovery using a novel system of tubular gas-permeable membranes accounted for 15% and 100% of the total VFA from effluent 1 (butyric, acetic, and propionic acids) and effluent 2 (mainly acetic acid), respectively. Full article

(This article belongs to the Special Issue Resource Recovery from Waste Biomass)

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17 pages, 399 KiB

Open AccessArticle

Reverse Logistics and the Circular Economy: A Study before and after the Implementation of the National Solid Waste Policy in Brazil

by Elias Carlos Aguirre Rodríguez, Cecilia Toledo Hernández, Elen Yanina Aguirre-Rodríguez, Aneirson Francisco da Silva and Fernando Augusto Silva Marins

Recycling 2024, 9(4), 64; https://doi.org/10.3390/recycling9040064 - 2 Aug 2024

Cited by 1 | Viewed by 1959

Abstract

This article analyzes Reverse Logistics (RL) practices associated with the concept of Circular Economy (CE), comparing studies conducted before and after the implementation of the National Solid Waste Policy (NSWP) in Brazil. Data from companies in the Sul Fluminense region were analyzed using [...] Read more.

This article analyzes Reverse Logistics (RL) practices associated with the concept of Circular Economy (CE), comparing studies conducted before and after the implementation of the National Solid Waste Policy (NSWP) in Brazil. Data from companies in the Sul Fluminense region were analyzed using the Analytic Hierarchy Process to prioritize RL practices and identify those related to CE. The research included companies from nine Brazilian economic sectors that engage in some form of RL. The comparison of results aimed to evaluate the influence of the NSWP on these practices, with data analyzed using the Super Decisions software (version 3.2) to establish priorities and aggregate them using the Aggregating Individual Priorities method. It was observed that the implementation of the NSWP in 2010 emphasized the importance of sustainability. Although the concept of CE is recent, its operationalization is based on consolidated RL practices such as recycling, remanufacturing, and material reuse. The study provides insights to optimize and expand these practices, facilitating the transition from a linear economy to a circular one. Full article

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14 pages, 1699 KiB

Open AccessReview

Circular Economy in Practice: A Literature Review and Case Study of Phosphogypsum Use in Cement

by Girts Bumanis, Danutė Vaičiukynienė, Tatjana Tambovceva, Liga Puzule, Maris Sinka, Dalia Nizevičienė, Ignacio Villalón Fornés and Diana Bajare

Recycling 2024, 9(4), 63; https://doi.org/10.3390/recycling9040063 - 27 Jul 2024

Viewed by 1886

Abstract

The utilization of waste generated from industrial production is a burden to overcome for society to reach a circular economy. Usually, production waste is associated with low-quality materials compared to its natural counterparts. In some cases, high-purity materials are generated, while different hazardous [...] Read more.

The utilization of waste generated from industrial production is a burden to overcome for society to reach a circular economy. Usually, production waste is associated with low-quality materials compared to its natural counterparts. In some cases, high-purity materials are generated, while different hazardous substances such as heavy metals, radioactive elements, or organic chemical substances are pollutants that often limit the materials’ further application. One such material that has accumulated for decades is phosphogypsum (PG). The extraction of fertilizers from metamorphous rocks results in large quantities of PG. Until now, PG has been deposited in large stockpiles near the production plant, causing problems for the environment in the surrounding area. However, the chemical composition of PG places it as a high-purity artificial gypsum material, which means that it could be used as a substitution or supplementary material in gypsum-based material production. The concerns, with respect to both legislation and prevailing prejudices in society, about its impurities strongly limit its application. This manuscript reviews current research practices for the effective use of PG and analyzes the importance of the circular economy. A life cycle assessment of current state-of-the-art technologies regarding PG application is proposed. Full article

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15 pages, 1221 KiB

Open AccessArticle

Environmental and Economic Forecast of the Widespread Use of Anaerobic Digestion Techniques

by Andrey Kiselev, Elena Magaril and Ramona Giurea

Recycling 2024, 9(4), 62; https://doi.org/10.3390/recycling9040062 - 26 Jul 2024

Viewed by 1062

Abstract

The concept of the circular economy represents the most relevant mainstream approach to reducing the negative environmental impact of waste. Anaerobic digestion has proved to be one of the leading and widely adopted techniques for sewage sludge treatment under the principles of the [...] Read more.

The concept of the circular economy represents the most relevant mainstream approach to reducing the negative environmental impact of waste. Anaerobic digestion has proved to be one of the leading and widely adopted techniques for sewage sludge treatment under the principles of the circular economy. The purpose of this study is to forecast environmental and economic indicators through modeling the extensive utilization of biogas technologies with a case study of an administrative territorial unit. The proposed methodological framework involves the use of averaged specific indicators and is based on the relationship between inhabitants, waste generation rates, biogas yield, greenhouse gas emission mitigation and biogas energy potential. The widespread use of anaerobic digestion techniques according to the proposed methodology in the instant scenario will ensure the biogas yield of 10 million Nm³ within the considered administrative territory unit with a population of 4.2 million P.E., which ultimately can be expressed in electricity and thermal generation potential of 20.8 and 24.8 million kWh*y, respectively, annual greenhouse gas elimination of 119.6 thousand tons of CO₂ equivalent and capital investment attraction of EUR 65.18 million. Furthermore, all sewage sludge will be subjected to disinfection and stabilization procedures to ensure its safe utilization. The findings of this study offer an opportunity for a wide range of stakeholders to assess the environmental and economic benefits of the widespread adoption of biogas technologies. The developed methodology can be utilized to inform management decisions through the use of the instant and scenario forecasts. Full article

(This article belongs to the Special Issue Resource Recovery from Waste Biomass)

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14 pages, 4095 KiB

Open AccessArticle

An Investigation into Sustainable Solutions: Utilizing Hydrated Lime Derived from Oyster Shells as an Eco-Friendly Alternative for Semiconductor Wastewater Treatment

by Hye-Jin Lee, Sang-Eun Lee and Seokhwi Kim

Recycling 2024, 9(4), 61; https://doi.org/10.3390/recycling9040061 - 26 Jul 2024

Viewed by 924

Abstract

Due to its acidic nature and high fluoride concentration, hydrated lime (Ca(OH)₂) is commonly used for neutralization and fluoride control in semiconductor wastewater treatment. This study investigated the efficacy of treating high fluoride-containing wastewater using hydrated lime derived from oyster shells [...] Read more.

Due to its acidic nature and high fluoride concentration, hydrated lime (Ca(OH)₂) is commonly used for neutralization and fluoride control in semiconductor wastewater treatment. This study investigated the efficacy of treating high fluoride-containing wastewater using hydrated lime derived from oyster shells as an alternative to limestone. Overall, the characteristics of removing pollutants in acidic wastewater using shell-based hydrated lime showed similar patterns to hydrated lime from limestone. The treatment efficiency was 50% or less under theoretical Ca/F molar ratio (=0.5) conditions for the formation of fluorite (CaF₂), while the fluorine removal rate reached 99% under somewhat higher Ca/F conditions due to the influence of ionic components in the wastewater. Interestingly, chloride content did not increase even in the initial reaction stages, in contrast to our concerns about oyster shells generally containing salt to a certain extent due to their growth in seawater; instead, the chloride concentration decreased over time, similar to nitrate (NO₃⁻). In controlling fluoride in wastewater, surpassing the theoretical Ca/F molar ratio, particularly considering the presence of other anionic species such as SO₄^²− and PO₄³⁻, the optimal Ca/F ratio for fluoride removal was found to be 1.59. This value is approximately 16% lower than the calculated value (Ca/F = 1.85) when accounting for other anions. X-ray diffraction results confirmed the presence of CaSO₄, Ca₃(PO₄)₂, and CaF₂ in the precipitate recovered after the reaction, indicating the effective removal of ionic contaminants. This observation suggests that oyster shell-derived hydrated lime could serve as a viable calcium resource for treating acidic wastewater and represents a potential alternative to traditional limestone-based methods. Full article

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12 pages, 4264 KiB

Open AccessArticle

Concentration of Silver from Recycling of Fine Powder of Wasted Videogame Printed Circuit Boards through Reverse Froth Flotation and Magnetic Separation Processes

by Rubén Flores-Campos, Rosa Hilda Estrada-Ruiz, Mario Rodríguez-Reyes, Diego Martínez-Carrillo and Antonia Martínez-Luévanos

Recycling 2024, 9(4), 60; https://doi.org/10.3390/recycling9040060 - 22 Jul 2024

Viewed by 1334

Abstract

Electronic waste stream grows day by day; printed circuit boards are a kind of solid waste that accounts for 6% of electronic waste. When these are discarded, they can cause soil, water, and air contamination; however, if recycled, these can be considered as [...] Read more.

Electronic waste stream grows day by day; printed circuit boards are a kind of solid waste that accounts for 6% of electronic waste. When these are discarded, they can cause soil, water, and air contamination; however, if recycled, these can be considered as a secondary source of metals. Physical comminution of printed circuit boards generates particles with sizes smaller than 250 µm, which are typically not included in the recycling process because they are considered as dust and unvaluable; nevertheless, precious and base metals can be found in these particles. The concentration of metals like silver, among others, from these particles can be achieved by reverse froth flotation in a flotation column followed by magnetic separation of the tails products. A mass balance of the flotation column feed, concentrate, and tails indicates that using a pulp modified with 5 ppm methyl isobutyl carbinol plus 5 g/ton oleic acid (both biodegradable reagents), the concentration of the products improved, resulting in recoveries of 86.13 and 13.87% in the concentrate and tails zones, respectively, with a grade of 74.4% in the tails flow. Magnetic separation of the tails product increases slightly the concentration of silver, reaching a silver grade of 74.5%, a recovery amount similar to those obtained employing complex and environmentally unfriendly processes. Full article

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49 pages, 1714 KiB

Open AccessArticle

Recent Developments in Technology for Sorting Plastic for Recycling: The Emergence of Artificial Intelligence and the Rise of the Robots

by Cesar Lubongo, Mohammed A. A. Bin Daej and Paschalis Alexandridis

Recycling 2024, 9(4), 59; https://doi.org/10.3390/recycling9040059 - 15 Jul 2024

Cited by 1 | Viewed by 5258

Abstract

Plastics recycling is an important component of the circular economy. In mechanical recycling, the recovery of high-quality plastics for subsequent reprocessing requires plastic waste to be first sorted by type, color, and size. In chemical recycling, certain types of plastics should be removed [...] Read more.

Plastics recycling is an important component of the circular economy. In mechanical recycling, the recovery of high-quality plastics for subsequent reprocessing requires plastic waste to be first sorted by type, color, and size. In chemical recycling, certain types of plastics should be removed first as they negatively affect the process. Such sortation of plastic objects at Materials Recovery Facilities (MRFs) relies increasingly on automated technology. Critical for any sorting is the proper identification of the plastic type. Spectroscopy is used to this end, increasingly augmented by machine learning (ML) and artificial intelligence (AI). Recent developments in the application of ML/AI in plastics recycling are highlighted here, and the state of the art in the identification and sortation of plastic is presented. Commercial equipment for sorting plastic recyclables is identified from a survey of publicly available information. Automated sorting equipment, ML/AI-based sorters, and robotic sorters currently available on the market are evaluated regarding their sensors, capability to sort certain types of plastics, primary application, throughput, and accuracy. This information reflects the rapid progress achieved in sorting plastics. However, the sortation of film, dark plastics, and plastics comprising multiple types of polymers remains challenging. Improvements and/or new solutions in the automated sorting of plastics are forthcoming. Full article

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11 pages, 1227 KiB

Open AccessArticle

A New Recycling Method through Mushroom Cultivation Using Food Waste: Optimization of Mushroom Bed Medium Using Food Waste and Agricultural Use of Spent Mushroom Substrates

by Babla Shingha Barua, Ami Nigaki and Ryota Kataoka

Recycling 2024, 9(4), 58; https://doi.org/10.3390/recycling9040058 - 15 Jul 2024

Viewed by 1745

Abstract

Food waste is generated in large amounts locally and globally, and requires expenditure for disposal. However, it has high nutritional value and almost no toxic components. Therefore, it can be returned to mushroom mediums for further use, leading to food waste circulation. Though [...] Read more.

Food waste is generated in large amounts locally and globally, and requires expenditure for disposal. However, it has high nutritional value and almost no toxic components. Therefore, it can be returned to mushroom mediums for further use, leading to food waste circulation. Though disposing of spent mushroom substrate (SMS) after harvesting is an additional problem, there have been increased efforts to compost it and apply it to the soil for growing vegetables. This study, therefore, aimed to optimize (1) mushroom spawn production with rice hull, (2) mushroom substrates using food waste to accelerate food waste recycling, and (3) the utilization of SMS as an organic fertilizer. An optimal substrate composition and high yield were obtained at 120–140 g of food waste per bag among substrates from Pleorutus ostreatus and Pleorutus citrinopileatus; therefore, using a high ratio of food waste in the mushroom mediums was achieved. On the other hand, the SMS of P. citrinopileatus demonstrated higher plant biomass growth, at 36 g, than that of P. ostreatus, at 21.2 g, in a treatment using SMS + okara. The present discovery is that people may be encouraged to be mindful of food loss by the delivery of mushrooms and plants grown from agro/food waste to the dining table, and this circular system may therefore be used as a key resource in mushroom and plant cultivation and to achieve a zero-emission cycle. Full article

(This article belongs to the Special Issue Resource Recovery from Waste Biomass)

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20 pages, 6358 KiB

Open AccessArticle

Investigation of the Effectiveness of Barrier Layers to Inhibit Mutagenic Effects of Recycled LDPE Films, Using a Miniaturized Ames Test and GC-MS Analysis

by Lukas Prielinger, Smarak Bandyopadhyay, Eva Ortner, Martin Novak, Tanja Radusin, Steffen Annfinsen, Nusrat Sharmin, Bernhard Rainer and Marit Kvalvåg Pettersen

Recycling 2024, 9(4), 57; https://doi.org/10.3390/recycling9040057 - 15 Jul 2024

Viewed by 1594

Abstract

To fulfil the European Green Deal targets and implement a circular economy, there is an urgent need to increase recycling rates of packaging materials. However, before recycled materials can be used in food contact applications, they must meet high safety standards. According to [...] Read more.

To fulfil the European Green Deal targets and implement a circular economy, there is an urgent need to increase recycling rates of packaging materials. However, before recycled materials can be used in food contact applications, they must meet high safety standards. According to the European Food Safety Authority (EFSA), a worst-case scenario must be applied and unknown substances must be evaluated as being potentially genotoxic. The Ames test, which detects direct DNA-reactive effects, together with chromatographic analysis is very promising to complement risk assessment. This study aims to evaluate the effectiveness of functional barriers in ten different samples, including virgin and recycled LDPE foils. FT-IR analysis did not show major differences between virgin and recycled films. Light microscopy revealed differences in quality and an increased number of particles. GC-MS analysis detected and quantified 35 substances, including eight unknowns. Using a miniaturized version of the Ames test, four of ten samples tested positive in two individual migrates up to a dilution of 12.5%. All virgin LDPE materials tested negative; however, recycled material F showed an increased mutagenic activity, with an n-fold induction up to 28. Samples with functional barriers lowered migration and reduced mutagenicity. Nonetheless, further investigations are needed to identify possible sources of contamination. Full article

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15 pages, 5830 KiB

Open AccessArticle

The Use of Nonmetallic Fraction Particles with the Double Purpose of Increasing the Mechanical Properties of Low-Density Polyethylene Composite and Reducing the Pollution Associated with the Recycling of Metals from E-Waste

by Rubén Flores-Campos, Rogelio Deaquino-Lara, Mario Rodríguez-Reyes, Roberto Martínez-Sánchez and Rosa Hilda Estrada-Ruiz

Recycling 2024, 9(4), 56; https://doi.org/10.3390/recycling9040056 - 3 Jul 2024

Cited by 1 | Viewed by 1502

Abstract

A restorative process, where the nonmetallic fraction from e-waste printed circuit boards is reused as a raw material for the conformation of a new polymer matrix composite with increased properties favoring its industrial applications, is proposed with a zero residues approach. Low density [...] Read more.

A restorative process, where the nonmetallic fraction from e-waste printed circuit boards is reused as a raw material for the conformation of a new polymer matrix composite with increased properties favoring its industrial applications, is proposed with a zero residues approach. Low density polyethylene pellets and nonmetallic fraction particles were mixed, and due to the generation of static electricity during the mixing process, the nonmetallic particles became attached to the polyethylene pellets; the blended material was fed into a screw extruder, producing filaments of the new composite. Mechanical properties increased as the particles content increased, presenting an ultimate tensile strength going from 20 for the raw low-density polyethylene to more than 60 MPa, and a yield strength that goes from 10 to 50 MPa on the composite with 6.0 wt.% particles. Also, the flammability of the composite improved, reducing its linear burning rate and increasing the time between detachment of two consecutive drops. Nonmetallic fraction particles were oriented in the extrusion direction and had a good adhesion with the polyethylene matrix. These composites can be employed for the production of prototypes using additive manufacture. Full article

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17 pages, 3806 KiB

Open AccessArticle

Quantifying Recycled Construction and Demolition Waste for Use in 3D-Printed Concrete

by Wibke De Villiers, Mwiti Mwongo, Adewumi John Babafemi and Gideon Van Zijl

Recycling 2024, 9(4), 55; https://doi.org/10.3390/recycling9040055 - 28 Jun 2024

Cited by 1 | Viewed by 1615

Abstract

Despite extensive regulations, the systemic under-reporting of construction and demolition waste generation rates pervades the South African waste sector due to the extensive and active informal waste management practices that are typical of developing countries. This study merges the rapid development of high-technology [...] Read more.

Despite extensive regulations, the systemic under-reporting of construction and demolition waste generation rates pervades the South African waste sector due to the extensive and active informal waste management practices that are typical of developing countries. This study merges the rapid development of high-technology 3D-printed concrete (3DPC) with the increasing pressure that the built environment is placing on both natural resource consumption and landfill space due to construction and demolition waste (CDW) by establishing an inventory of CDW that is suitable for use in 3DPC in South Africa. This is an essential step in ensuring the technical, economic, and logistical viability of using CDW as aggregate or supplementary cementitious materials in 3DPC. Of the methods considered, the lifetime material analysis and per capita multiplier methods are the most appropriate for the context and available seed data; this results in CDW estimates of 24.3 Mt and 12.2 Mt per annum in South Africa, respectively. This range is due to the different points of estimation for the two methods considered, and the per capita multiplier method provides an inevitable underestimation. In order to contextualise the estimated availability of CDW material for use in concrete in general, the demand for coarse and fine aggregate and supplementary cementitious material in South Africa is quantified as 77.9 Mt. This overall annual demand far exceeds the estimated CDW material (12.2–24.3 Mt) available as an alternative material source for concrete. Full article

(This article belongs to the Special Issue Sustainable Management in Eco-Materials, Industrial Residues and Construction and Demolition Waste)

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9 pages, 1387 KiB

Open AccessArticle

Selective Recovery of Tin from Electronic Waste Materials Completed with Carbothermic Reduction of Tin (IV) Oxide with Sodium Sulfite

by Wojciech Hyk and Konrad Kitka

Recycling 2024, 9(4), 54; https://doi.org/10.3390/recycling9040054 - 26 Jun 2024

Viewed by 1976

Abstract

A new approach for the thermal reduction of tin dioxide (SnO₂) in the carbon/sodium sulfite (Na₂SO₃) system is demonstrated. The process of tin smelting was experimentally optimized by adjusting the smelting temperature and amounts of the chemical [...] Read more.

A new approach for the thermal reduction of tin dioxide (SnO₂) in the carbon/sodium sulfite (Na₂SO₃) system is demonstrated. The process of tin smelting was experimentally optimized by adjusting the smelting temperature and amounts of the chemical components used for the thermal reduction of SnO₂. The numbers obtained are consistent with the thermodynamic characteristics of the system and molar fractions of reactants derived from the proposed mechanism of the SnO₂ thermal reduction process. They reveal that the maximum yield of tin is obtained if masses of C, Na₂SO₃ and SnO₂ are approximately in the ratio 1:2:3 and the temperature is set to 1050 °C. The key role in the suggested mechanism is the thermal decomposition of Na₂SO₃. It was deduced from the available experimental data that the produced sulfur dioxide undergoes carbothermic reduction to carbonyl sulfide—an intermediate product involved in the bulk reduction of SnO₂. Replacing sodium sulfite with sodium sulfate, sodium sulfide and even elemental sulfur practically terminated the production of metallic tin. The kinetic analysis was focused on the determination of the reaction orders for the two crucial reactants involved in the smelting process. Full article

(This article belongs to the Special Issue Emerging Technologies in the Hydrometallurgical Recycling of Critical Metals)

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18 pages, 5818 KiB

Open AccessArticle

Sludge-Based Superparamagnetic Nano-Sorbent Functionalized by Lanthanum Silicate Nanorods for Phosphorus Adsorption and Fertilization

by Qian Zhao, Xiaole Wang, Juan Ren, Wei Wang, Jingtao Xu, Shujuan Meng, Jiarou Jin, Xiaochen Li, Yuyang Fu, Kechao Han, Ruimin Mu, Xinyi Li, Renbo Zhao, Hongbo Wang and Feiyong Chen

Recycling 2024, 9(4), 53; https://doi.org/10.3390/recycling9040053 - 24 Jun 2024

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Abstract

Phosphorus (P) recovery from wastewater is considered to be a positive human intervention towards sustainable P use in the global P cycle. This study investigated the feasibility of synthesizing a superparamagnetic nano-sorbent that was functionalized by lanthanum silicate nanorods (NR_La-Si) using [...] Read more.

Phosphorus (P) recovery from wastewater is considered to be a positive human intervention towards sustainable P use in the global P cycle. This study investigated the feasibility of synthesizing a superparamagnetic nano-sorbent that was functionalized by lanthanum silicate nanorods (NR_La-Si) using drinking water treatment sludge (DWTS), evaluating both its P adsorption capacity and fertilization effect. The DWTS-based La-modified P nano-sorbent (P-sorbent _D) exhibited complicated but single-layer-dominant adsorption for phosphate, with a maximum adsorption capacity up to 26.8 mg/g, which was superior to that of most of the similar sludge-based P-sorbent. The NR_La-Si-modified P-sorbent _D was identified with several characterization techniques and the leaching metal elements from the nano-sorbent were tested, which were below the limits proposed by the Food and Agriculture Organization of the United Nations. In addition, the growth and vigorousness of Arabidopsis thaliana indicated that the exhausted P-sorbent _D could be used as a potential water-soluble moderate-release P fertilizer, which was also confirmed by the well-fitted P uptake model and the P desorption pattern from the sorbent–fertilizer. The doped lanthanum silicate nanorods could play the dual role of P complexation enhancement and health/growth promotion. In light of this, this study proposed a new way of reclaiming DWTS as a P-sorbent for fertilization, offering new insights into the path toward “closing the P loop”. Full article

(This article belongs to the Special Issue Reuse of Wastewater: Recovery of Water, Nutrients, and Energy—2nd Edition)

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16 pages, 3892 KiB

Open AccessArticle

Sustainability in the Generation of Household Waste from Dishwasher Sponges for the Purpose of a New Adsorbent Material and Its Operating Costs

by Daniel Mantovani, Luís Fernando Cusioli, Diana Aline Gomes, Rosângela Bergamasco, Angelo Marcelo Tusset and Giane Gonçalves Lenzi

Recycling 2024, 9(4), 52; https://doi.org/10.3390/recycling9040052 - 23 Jun 2024

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Abstract

The major problems related to environmental pollution are increasingly present among us. The uncontrolled use and incorrect disposal of products means that these problems are increasing at frightening rates. In this context, a major related problem is the incorrect disposal of dishwasher sponges [...] Read more.

The major problems related to environmental pollution are increasingly present among us. The uncontrolled use and incorrect disposal of products means that these problems are increasing at frightening rates. In this context, a major related problem is the incorrect disposal of dishwasher sponges that are no longer useful; their material being made up of petroleum derivatives causes this problem to be leveraged in the environment. In the present work, we evaluated and carried out tests in which these dirty sponges that would be discarded were used for the purpose of developing new sustainable adsorbent materials. These materials were washed and dried, crushed and made available for use, by which they were kept in contact with a paracetamol solution, evaluating the effect of mass, pH, kinetics, equilibrium, thermodynamic parameters, and cost analyses. The results demonstrated an adsorptive capacity of approximately 40 mg g⁻¹ and its cost was relatively viable, since this material would otherwise be discarded incorrectly. In conclusion, this material achieved the good removal of this studied contaminant and became an economical, viable, and ecologically viable material. Full article

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Recycling, Volume 9, Issue 4 (August 2024) – 19 articles

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