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Recycling, Volume 8, Issue 1 (February 2023) – 28 articles

Cover Story (view full-size image): In a world where natural resources are limited, the development of efficient recycling strategies is paramount. Electric and electronic equipment are part of our daily life, but what happens when they become obsolete and turn into e-wastes? Due to the rich content of metals, especially critical raw materials, e-waste is a real urban mine to be valorised. Bio-metallurgy is a promising strategy for e-waste recycling based on biological routes of specialised microorganisms able to leach solid-containing metals. Archaea, the most ancient organisms on Earth, has intrinsic abilities that have not yet been fully explored. Here, we report on the state of the art of Archaea exploitation in critical metal recovery from e-waste and related industrial applications, bringing attention to the potential coupling with CO2-rich streams’ upgrade into methane. View this paper
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15 pages, 1786 KiB  
Article
Effectiveness of the IoT in Regional Energy Transition: The Smart Bin Case Study
by Dimitris Ziouzios and Minas Dasygenis
Recycling 2023, 8(1), 28; https://doi.org/10.3390/recycling8010028 - 20 Feb 2023
Cited by 6 | Viewed by 3634
Abstract
As part of the European Green Deal, the EU aims to become climate-neutral and reach net-zero greenhouse gas emissions by 2050. Lignite has long dominated the electricity system of Greece, providing cheap and reliable energy, given the abundant and low-cost domestic resources at [...] Read more.
As part of the European Green Deal, the EU aims to become climate-neutral and reach net-zero greenhouse gas emissions by 2050. Lignite has long dominated the electricity system of Greece, providing cheap and reliable energy, given the abundant and low-cost domestic resources at the cost of increased emission. In line with its national and international commitments to climate action, Greece needs to urgently transform its energy system and overcome its technological lock-ins, paving the way for a net-zero emission economy by the mid-century. The Internet of Things plays a significant role in this direction, providing with its technologies the protection of the environment and creating new jobs. The smart bins constitute an interesting proposal for areas in the energy transition. This research work reflects the current situation in the region of Western Macedonia and proposes the smart bin project as a part of the solution in the transition to the post-lignite era. For this purpose, survey research has been conducted in the municipalities of Greece on waste management technology. Full article
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26 pages, 1127 KiB  
Article
The Effects of Data Security and Perceived Benefits on Mobile Phone Recycling Behaviour and the Recycling Intention Mediation Role
by Taher Ben Yahya, Noriza Mohd Jamal, Balan Sundarakani and Siti Zaleha Omain
Recycling 2023, 8(1), 27; https://doi.org/10.3390/recycling8010027 - 18 Feb 2023
Cited by 5 | Viewed by 3243
Abstract
Mobile phones are the most heavily utilised electronic devices on a global scale. Since they are relatively smaller than other electronic devices, unlike other electronic waste (e-waste), they are not disposed of properly. Hence, this study examines the factors influencing mobile phone users’ [...] Read more.
Mobile phones are the most heavily utilised electronic devices on a global scale. Since they are relatively smaller than other electronic devices, unlike other electronic waste (e-waste), they are not disposed of properly. Hence, this study examines the factors influencing mobile phone users’ overall intention to recycle their mobile phones. The factors used originate from the theory of planned behaviour (TPB), but additional factors were also included, namely, perceived benefits and data security, to allow for a more in-depth analysis of customer behaviour. Partial least squares structural equation modelling (PLS-SEM) was employed to analyse 601 results from the United Arab Emirates (UAE) through a self-administered online survey. The results demonstrate that perceived benefits (whether environmental or financial) and perceived behavioural control possess the most statistically significant positive effects on the UAE mobile phone users’ intention to participate in reverse supply chain (RSC) processes such as refurbishing or recycling. The impacts of attitude and subjective norms were the second most positive influences. Meanwhile, only 7% of UAE mobile phone users were significantly impacted by data security in participating in RSC processes. Additionally, recycling intention had no noticeable mediation effect on the relationship among the TPB variables and the extended variables (namely, data security and perceived benefits) and mobile phone recycling behaviour. The study offers confidence to industrial players in implementing these particular factors in their reverse supply chain management (RSCM) systems to influence more users to return end-of-life (EOL) or end-of-use (EOU) mobile phones, which could, in return, assist in resource preservation and environmental protection. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2022)
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15 pages, 1203 KiB  
Article
Recycling of Post-Consumer Polystyrene Packaging Waste into New Food Packaging Applications—Part 1: Direct Food Contact
by Frank Welle
Recycling 2023, 8(1), 26; https://doi.org/10.3390/recycling8010026 - 16 Feb 2023
Cited by 7 | Viewed by 4897
Abstract
The increase in plastic recycling is an essential pre-requisite for the transition to a circular economy. Polystyrene (PS) is a low diffusive polymer and therefore a promising candidate for recycling back into food contact similar to polyethylene terephthalate (PET). However, such a recycling [...] Read more.
The increase in plastic recycling is an essential pre-requisite for the transition to a circular economy. Polystyrene (PS) is a low diffusive polymer and therefore a promising candidate for recycling back into food contact similar to polyethylene terephthalate (PET). However, such a recycling of PS cups has been not established to date on a commercial scale. Even if recycling back into food contact is desired, the health of the consumer must not be at risk. As a consequence, recycling processes must go through a conservative assessment by relevant authorities. For PS, however, evaluation criteria are not published, which is a drawback for process developers. Within the study, post-consumer PS recyclates were evaluated in a similar way to existing evaluation criteria for PET and HDPE. For the recycling of post-consumer PS back into packages with direct contact with food, there are still some points open which cannot be answered conclusively today. Upon closer inspection, there appears to be enough information available to give a first indication as to whether recycling of post-consumer PS packaging materials back into direct food contact can be considered safe. The knowledge gaps in PS recycling were determined and discussed. Full article
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14 pages, 1836 KiB  
Article
Assessing the Sorting Efficiency of Plastic Packaging Waste in an Italian Material Recovery Facility: Current and Upgraded Configuration
by Giovanni Gadaleta, Sabino De Gisi, Francesco Todaro, Giuseppe D’Alessandro, Silvio Binetti and Michele Notarnicola
Recycling 2023, 8(1), 25; https://doi.org/10.3390/recycling8010025 - 12 Feb 2023
Cited by 11 | Viewed by 3293
Abstract
The first step in reintroducing plastic waste into the recycling cycle is to use material recovery facilities (MRFs). However, while the composition and types of plastic waste are changing over time, the layout of MRFs does not always adapt to this change. In [...] Read more.
The first step in reintroducing plastic waste into the recycling cycle is to use material recovery facilities (MRFs). However, while the composition and types of plastic waste are changing over time, the layout of MRFs does not always adapt to this change. In this paper, an existing MRF in Southern Italy was chosen as a reference to evaluate its current performance and to estimate possible improvements in sorting through a specific upgrade. First, an analysis of the amount, composition, and sources (in terms of type of waste and distance from the MRF) of the input waste was conducted. The composition of the input waste was then compared with the amount of selected output waste streams in order to calculate the current sorting efficiency of each stream and compare it with the values obtained from the upgrade. Lastly, the current performance of the plant was compared with a previous assessment of the same MRF in order to highlight possible variation. Results showed how the incoming waste was mainly composed of packaging plastic waste, and that some plastic waste not yet selected by the plant ended up in specific output streams. Therefore, the current performance of the MRF resulted high for PET and PE bottles (80.2% and 92.8%, respectively), in contrast to mixed or flexible packaging, where the efficiency achieved lower values (55–50%). These values were caused by a weakness in the 2D flow sorting line, which the upgrade mostly addressed. The upgraded configuration increased the production of recyclable waste from 34.32% to 50.39%, especially due to the recovery of small flexible packaging films in PE and biopolymers. Full article
(This article belongs to the Special Issue Sustainable Recycling of Municipal Solid Waste)
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19 pages, 8535 KiB  
Article
Identification and Evaluation of (Non-)Intentionally Added Substances in Post-Consumer Recyclates and Their Toxicological Classification
by Christian Rung, Frank Welle, Anita Gruner, Arielle Springer, Zacharias Steinmetz and Katherine Munoz
Recycling 2023, 8(1), 24; https://doi.org/10.3390/recycling8010024 - 9 Feb 2023
Cited by 12 | Viewed by 6841
Abstract
According to the European circular economy strategy, all plastic packaging placed on the market by 2030 has to be recyclable. However, for recycled plastics in direct contact with food, there are still major safety concerns because (non-)intentionally added substances can potentially migrate from [...] Read more.
According to the European circular economy strategy, all plastic packaging placed on the market by 2030 has to be recyclable. However, for recycled plastics in direct contact with food, there are still major safety concerns because (non-)intentionally added substances can potentially migrate from recycled polymers into foodstuffs. Therefore, the European Food Safety Authority (EFSA) has derived very low migration limits (e.g., 0.1 µg/L for recycled polyethylene terephthalate (PET) and 0.06 µg/L for recycled high-density polyethylene (HDPE)) for recycled polymers. Thus, the use of recyclates from post-consumer waste materials in direct food contact is currently only possible for PET. A first step in assessing potential health hazards is, therefore, the identification and toxicological classification of detected substances. Within this study, samples of post-consumer recyclates from different packaging-relevant recycling materials (HDPE, LDPE, PE, PP, PET, and PS) were analyzed. The detected substances were identified and examined with a focus on their abundance, toxicity (Cramer classification), polarity (log P values), chemical diversity, and origin (post-consumer substances vs. virgin base polymer substances). It was demonstrated that polyolefins contain more substances classified as toxic than PET, potentially due to their higher diffusivity. In addition, despite its low diffusivity compared to polyolefins, a high number of substances was found in PS. Further, post-consumer substances were found to be significantly more toxicologically concerning than virgin base polymer substances. Additionally, a correlation between high log P values and a high Cramer classification was found. It was concluded that PET is currently the only polymer that complies with EFSA’s requirements for a circular economy. However, better-structured collection systems and cleaning processes, as well as more analytical methods that enable a highly sensitive detection and identification of substances, might offer the possibility of implementing other polymers into recycling processes in the future. Full article
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10 pages, 842 KiB  
Article
Recycling of Plastic Food Packages: A Case Study with Finnish University Students
by Jarmo Alarinta, Margit Närvä and Gun Wirtanen
Recycling 2023, 8(1), 23; https://doi.org/10.3390/recycling8010023 - 9 Feb 2023
Cited by 1 | Viewed by 4253
Abstract
Recycling, depositing, and proper discarding of plastics are significant means to reduce plastics in the environment. The purpose of this study was to monitor both the type and amount of plastic food packages recycled, reused, and discarded in Finnish households with at least [...] Read more.
Recycling, depositing, and proper discarding of plastics are significant means to reduce plastics in the environment. The purpose of this study was to monitor both the type and amount of plastic food packages recycled, reused, and discarded in Finnish households with at least one university student. The participating students came from various universities of applied sciences. They participated in courses related to sustainable food systems at Seinäjoki University of Applied Sciences. In total, 785 approved participants from 363 households took part in one-week monitoring. The focus was to quantify the number of food packages used and specify how the respondents handled the food packages after use. This study shows that the recycling rate of plastic packages in Finnish households was 61%. Bigger households produce less packaging waste per person than one- or two-person households. Furthermore, the recycling activity in single-person households was lower than for two- and three-person households. The Finnish deposit system for drink packages encourages people to recycle packages. This reduces municipal waste. Recycling requires knowledge of the plastic material used in food packages. Full article
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16 pages, 3511 KiB  
Article
The Effect of Recycled Citrogypsum as a Supplementary Mineral Additive on the Physical and Mechanical Performance of Granulated Blast Furnace Slag-Based Alkali-Activated Binders
by Natalia I. Kozhukhova, Nataliya I. Alfimova, Marina I. Kozhukhova, Ivan S. Nikulin, Roman A. Glazkov and Anna I. Kolomytceva
Recycling 2023, 8(1), 22; https://doi.org/10.3390/recycling8010022 - 7 Feb 2023
Cited by 5 | Viewed by 1997
Abstract
In the last decades, gypsum-bearing industrial wastes become one of the common globally produced industrial and domestic wastes that are currently recycled and further utilized. In this study, the gypsum-bearing waste citrogypsum was used as a Ca2+-containing component to modify the [...] Read more.
In the last decades, gypsum-bearing industrial wastes become one of the common globally produced industrial and domestic wastes that are currently recycled and further utilized. In this study, the gypsum-bearing waste citrogypsum was used as a Ca2+-containing component to modify the properties of alkali-activated cement (AAC) based on granulated blast-furnace slag (GBFS). Citrogypsum was used in different AAC mixes activated with three different alkaline components: Na2CO3, NaOH, and Na2SiO3. Laser granulometry was applied to assess the granulometric characteristics of citrogypsum and GBFS. Specific gravity (SG), compressive strength, and water resistance were tested to evaluate the effect of citrogypsum on the physical and strength performance of AAC. Experimental results obtained over 4-day to 28-day time periods for the studied AACs showed that the addition of citrogypsum had a detrimental effect on the properties of AAC mixes, where decreases in compressive strength between 1 and 100%, decreases in specific gravity between 4 and 30%, and decreases in water resistance between 12 and 100% were observed. It was determined that AAC mixes modified with citrogypsum cured in ambient conditions had compressive strength values 61% to 90% lower than those cured in hydrothermal conditions. In terms of strength performance, specific gravity and water resistance, citrogypsum showed the greatest effect on AAC mixes activated with NaOH, and to a lesser extent, on mixes activated with Na2CO3. The highest water resistance value of 0.77 was observed for the AAC mixes activated with Na2CO3 cured in ambient conditions, and when cured in hydrothermal conditions, the highest water resistance reached up to 0.84 for the AAC mixes activated with NaOH. It was observed that the type of alkaline activator and curing conditions are both crucial factors that govern the response of citrogypsum as a supplementary mineral additive in GBFS-based AAC mixes in regard to compressive strength, specific gravity and water resistance. Full article
(This article belongs to the Special Issue Sustainable Materials from Waste and Renewable Sources)
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22 pages, 1592 KiB  
Article
A Zero-Waste Campus Framework: Perceptions and Practices of University Campus Community in Malaysia
by Mayawi Baba-Nalikant, Sharifah Mashita Syed-Mohamad, Mohd Heikal Husin, Nor Athiyah Abdullah, Mohamad Saifudin Mohamad Saleh and Asyirah Abdul Rahim
Recycling 2023, 8(1), 21; https://doi.org/10.3390/recycling8010021 - 6 Feb 2023
Cited by 7 | Viewed by 6129
Abstract
This paper will explore the university campus community’s perspective towards the realization of a zero-waste campus. A qualitative approach is employed to identify the factors influencing the campus community’s awareness and participation in solid waste management (SWM). Perceptions, attitudes, beliefs, opinions, and ideas [...] Read more.
This paper will explore the university campus community’s perspective towards the realization of a zero-waste campus. A qualitative approach is employed to identify the factors influencing the campus community’s awareness and participation in solid waste management (SWM). Perceptions, attitudes, beliefs, opinions, and ideas of Universiti Sains Malaysia (USM) campus community members are explored in focus group discussions (FGD) to determine the main factors influencing their zero-waste pro-environmental behaviour (PEB). The in-depth interview (IDI) is used to learn more about the university campus community’s perspectives on the themes defined by the FGD. The instruments were developed based on the adaption and adoption of previous studies, especially in reference to Kollmuss and Agyeman’s 2002 Model of Pro-Environmental Behaviour and a modified Knowledge-Attitude-Practices model. The findings show that environmental goals, environmental education, personal waste-related experience, environmental policy, environmental self-awareness, reinforcement contingencies, community engagement, social responsibilities, exemplary leadership, and social media influence the campus community’s zero-waste PEB. A framework based on an adaptation of Kollmuss and Agyeman’s model of pro-environmental behaviour is proposed to promote sustainable pro-environmental behaviour towards a Zero-Waste Campus. Full article
(This article belongs to the Topic Solid Waste Management)
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20 pages, 1804 KiB  
Review
Highlighting the Role of Archaea in Urban Mine Waste Exploitation and Valorisation
by Annalisa Abdel Azim, Ruggero Bellini, Arianna Vizzarro, Ilaria Bassani, Candido Fabrizio Pirri and Barbara Menin
Recycling 2023, 8(1), 20; https://doi.org/10.3390/recycling8010020 - 4 Feb 2023
Cited by 4 | Viewed by 4030
Abstract
E-materials become e-waste once they have been discarded without the intent of reuse. Due to its rich content of metals, among which many are Critical Raw Materials (CRMs), e-waste can be considered an urban mine to exploit and valorise. Common metal refining is [...] Read more.
E-materials become e-waste once they have been discarded without the intent of reuse. Due to its rich content of metals, among which many are Critical Raw Materials (CRMs), e-waste can be considered an urban mine to exploit and valorise. Common metal refining is performed by energy-intensive processes frequently based on the use of fossil fuel. Bio-metallurgy is a promising alternative for e-waste valorisation based on biological routes of specialised microorganisms able to leach solid-containing metals. Because of the physiology of these microorganisms, microbial leaching can be economically feasible, besides being an environmentally sustainable process. Like Bacteria and Fungi, Archaea are also capable of metal leaching activity, though their potential is underestimated. Among them, the extremophiles are the most studied and applied in the field of metal recovery, while mesophilic species are less common but still of high interest. Here we provide the state of industrial application of bio-metallurgy and report on the state of the art of Archaea exploitation in metal recovery from e-waste. Moreover, we give a special highlight to methanogenic archaea, which are able to convert CO2 into methane in order to highlight the potential for the valorisation of CO2-rich industrial streams generated by key processes (i.e., anaerobic digestion, concrete, and steel production) in CH4 for gas grid distribution, while making metals content in e-waste available again as raw material. Full article
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12 pages, 3908 KiB  
Article
Thermal and Sound Insulation Properties of Recycled Expanded Polystyrene Granule and Gypsum Composites
by Girts Bumanis, Pauls Pavils Argalis, Genadijs Sahmenko, Deniss Mironovs, Sandris Rucevskis, Aleksandrs Korjakins and Diana Bajare
Recycling 2023, 8(1), 19; https://doi.org/10.3390/recycling8010019 - 3 Feb 2023
Cited by 8 | Viewed by 3017
Abstract
Up to now, primary resources have been the main choice of raw material selection for production. Now, global market tendencies have brought significant attention to secondary resources as the price has been raised for primary materials, and there is a shortage of their [...] Read more.
Up to now, primary resources have been the main choice of raw material selection for production. Now, global market tendencies have brought significant attention to secondary resources as the price has been raised for primary materials, and there is a shortage of their delivery. This could bring an additional effort to increase the recycling level of construction and demolition waste, including expanded polystyrene (EPS). Efforts have been made to develop new efficient building materials with a high content of recycled EPS. In this paper, composite insulation material made of gypsum hemihydrate and recycled EPS beads by casting and compression methods were evaluated, and properties were compared. Thermal and sound insulation properties were characterized. Density from 48 to 793 kg/m3 was obtained and the thermal conductivity coefficient from 0.039 to 0.246 W/(m·K) was measured. Compression strength was from 18 kPa to 2.5 MPa. Composites produced with the compression method have a sound absorption coefficient α > 0.9 in the range from 600 to 700 Hz, while the samples produced by casting showed poor sound absorption with wide deviation. Compression methods had an advantage over the casting method as more homogenous and lightweight materials were produced with improved insulation properties. Full article
(This article belongs to the Special Issue Sustainable Materials from Waste and Renewable Sources)
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18 pages, 997 KiB  
Article
Quality Aspects in the Compounding of Plastic Recyclate
by Maximilian Auer, Jannick Schmidt, Jan Diemert, Gabriel Gerhardt, Maximilian Renz, Viola Galler and Jörg Woidasky
Recycling 2023, 8(1), 18; https://doi.org/10.3390/recycling8010018 - 31 Jan 2023
Cited by 4 | Viewed by 3684
Abstract
Compounding is the final processing step for quality adjustment and control before recycled thermoplastic polymer material can be introduced into production processes. Motivated by the need for higher recyclate shares, the research question is which quality problems recycling compounders are encountered in practice, [...] Read more.
Compounding is the final processing step for quality adjustment and control before recycled thermoplastic polymer material can be introduced into production processes. Motivated by the need for higher recyclate shares, the research question is which quality problems recycling compounders are encountered in practice, where they occur, and which mitigation options might be reasonable. Therefore, an online survey with 20 recycling compounders based in Germany was conducted asking about typical processing steps and processed materials, test procedures for quality assurance, quality problems, and possibilities for reducing quality problems. Results show that compounders mainly name impurities and contaminations of the input material as challenging and the reason for quality problems. The study shows that the problems are not dependent on the material input type. Quality problems occur along the entire secondary value chain, with companies manufacturing components themselves being particularly affected. The composition determination of the input materials helps to minimize quality problems. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2022)
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18 pages, 489 KiB  
Review
Trends in Extraction of Rare Earth Elements from Coal Ashes: A Review
by Gjergj Dodbiba and Toyohisa Fujita
Recycling 2023, 8(1), 17; https://doi.org/10.3390/recycling8010017 - 30 Jan 2023
Cited by 8 | Viewed by 5341
Abstract
The demand for novel, cost-effective, and environmentally friendly rare earth element and yttrium (REY) sources is essential. The recovery of REY and other valuable components from coal fly ash (CFA) may result in securing alternative resources, decreased disposal costs, and environmental protection, all [...] Read more.
The demand for novel, cost-effective, and environmentally friendly rare earth element and yttrium (REY) sources is essential. The recovery of REY and other valuable components from coal fly ash (CFA) may result in securing alternative resources, decreased disposal costs, and environmental protection, all of which may have positive effects. However, research on the recovery of REY from CFA is underway, and it is still necessary to assess its viability from an economic and environmental standpoint. The authors have reviewed some of the most recent advances in extracting rare earth elements from CFA. However, most techniques reported for the treatment of CFA are still at the laboratory scale. Nevertheless, there are several pathways for industrial-scale applications. Therefore, CFA treatment and the extraction of valuable products from it have considerable potential for reducing both its carbon footprint and environmental burden. Full article
(This article belongs to the Special Issue Featured Reviews in Recycling)
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11 pages, 1601 KiB  
Article
Fruit and Restaurant Waste Polysaccharides Recycling Producing Xylooligosaccharides
by Beatriz Salustiano Pereira, Alison Andrei Schmatz, Caroline de Freitas, Fernando Masarin and Michel Brienzo
Recycling 2023, 8(1), 16; https://doi.org/10.3390/recycling8010016 - 26 Jan 2023
Cited by 4 | Viewed by 2332
Abstract
A significant part of fruit production is wasted annually, a material of high value without use, causing environmental and social damage. These residues from agro-industrial processes, or those that can no longer be used in the market, can be recycled and generate value-added [...] Read more.
A significant part of fruit production is wasted annually, a material of high value without use, causing environmental and social damage. These residues from agro-industrial processes, or those that can no longer be used in the market, can be recycled and generate value-added products by pretreatments/hydrolysis. One of the important pretreatments is acid hydrolysis, which can produce xylooligosaccharides (XOS) from biomass, a product of great commercial value in the food and pharmaceutical markets, mainly due to its prebiotic potential. Bananas, oranges, and guava generate a large volume of waste and represent much of Brazil’s fruit production. The dilute acid hydrolysis resulted in XOS production of 37.69% for banana peel, 59.60% for guava bagasse, 28.70% for orange bagasse, and 49.64% for restaurant residue. XOS were quantified by a liquid chromatograph system with a Bio-Rad Aminex HPX-87C column. The results show that, for this type of material and hydrolysis, the ideal conditions to produce XOS are high temperature, low time, and high acid concentration for banana peel residue (160 °C, 15 min, and 3% H2SO4), low temperature, low time, and high acid concentration for guava bagasse (100 °C,15 min and 3% H2SO4), high temperature and acid concentration with low time for orange bagasse (160 °C,15 min and 3% H2SO4) and high temperature and time and high acid concentration for restaurant waste (160 °C, 55 min and 3% H2SO4). This study identified acid hydrolysis conditions that maximized XOS production with a low amount of xylose production using agro-industrial and food residues, also showing the high potential of the chosen residues through the high yields of XOS production. Full article
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24 pages, 9422 KiB  
Article
Life Cycle Assessment (LCA) of 3D Concrete Printing and Casting Processes for Cementitious Materials Incorporating Ground Waste Tire Rubber
by Matteo Sambucci, Ilario Biblioteca and Marco Valente
Recycling 2023, 8(1), 15; https://doi.org/10.3390/recycling8010015 - 20 Jan 2023
Cited by 12 | Viewed by 4706
Abstract
Ordinary concrete is an indispensable construction material of modern society which is used for everything from mundane road pavements to building structures. However, it is often used for non-load-bearing applications (for instance, insulating lightweight building units) where mechanical strength is not a priority. [...] Read more.
Ordinary concrete is an indispensable construction material of modern society which is used for everything from mundane road pavements to building structures. However, it is often used for non-load-bearing applications (for instance, insulating lightweight building units) where mechanical strength is not a priority. This leads to an avoidable depletion of natural aggregates which could instead be replaced by alternative waste materials capable of conferring to the material the desired performance while ensuring a “green” route for their disposal. Furthermore, the automation of production processes via 3D printing can further assist in the achievement of a more advanced and sustainable scenario in the construction sector. In this work, performance and environmental analyses were conducted on a 3D-printable cementitious mix engineered with ground waste tire rubber aggregates. The research proposed a comparative study between rubberized concrete mixes obtained by 3D printing and traditional mold-casting methods to achieve a comprehensive analysis in terms of the mix design and manufacturing process. To evaluate the environmental performance (global warming potential and cumulative energy demand) of the investigated samples, Life Cycle Assessment models were built by using the SimaPro software and the Ecoinvent database. The Empathetic Added Sustainability Index, which includes mechanical strength, durability, thermo-acoustic insulation, and environmental indicators, was defined to quantify the overall performance of the samples in relation to their engineering properties and eco-footprint. Full article
(This article belongs to the Special Issue Recycling of Rubber Waste)
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3 pages, 169 KiB  
Editorial
Acknowledgment to the Reviewers of Recycling in 2022
by Recycling Editorial Office
Recycling 2023, 8(1), 14; https://doi.org/10.3390/recycling8010014 - 13 Jan 2023
Viewed by 1178
Abstract
High-quality academic publishing is built on rigorous peer review [...] Full article
14 pages, 4415 KiB  
Article
Pyro-Hydrometallurgy Routes to Recover Silica from Indonesian Ferronickel Slag
by Reza M. Ulum, Natalin, Rini Riastuti, Wahyu Mayangsari, Agus B. Prasetyo, Johny W. Soedarsono and Ahmad Maksum
Recycling 2023, 8(1), 13; https://doi.org/10.3390/recycling8010013 - 13 Jan 2023
Cited by 5 | Viewed by 2939
Abstract
Ferronickel slag is a by-product of nickel smelting that provides an abundant silica source. Based on data, every ton of nickel production is equal to eight tons of ferronickel slag production, increasing without any recycling process. It is essential to create an end-to-end [...] Read more.
Ferronickel slag is a by-product of nickel smelting that provides an abundant silica source. Based on data, every ton of nickel production is equal to eight tons of ferronickel slag production, increasing without any recycling process. It is essential to create an end-to-end process for nickel production and its by-products because this would be a problem in the future and is relevant for many industrialized countries. This study describes a strategy to process ferronickel slag to produce silica. A pyrometallurgy–hydrometallurgy process and ferronickel slag were used to increase the silica content. The process was conducted through alkali fusion; the ferronickel slag was mixed with sodium carbonate at a temperature of 1000 °C for an hour and continued via leaching, precipitation, and cleaning processes. The leaching process was conducted with four concentrations (4 M, 6 M, 8 M, and 10 M) of sodium hydroxide and three different leaching durations (2 h, 4 h, and 6 h). Using hydrochloric acid (HCl) at pH 2 and deionized (DI) water cleaning, the precipitation process was adopted to synthesize a silica powder with the lowest agglomeration and enhance its purity. Characterization was carried out using X-ray Diffraction (XRD), Scanning Electron Microscopy–Energy-Dispersive Emission (SEM-EDS), X-ray Fluorescence (XRF), and Inductively Coupled Plasma–Optical Emission Spectroscopy (ICP-OES). This study highlighted silica characteristics that indicate high recovery by 85% through alkali fusion, HCl leaching, precipitation, and deionized water cleaning. Full article
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13 pages, 9604 KiB  
Article
Comparison between the Mechanical Recycling Behaviour of Amorphous and Semicrystalline Polymers: A Case Study
by André A. Costa, Pedro G. Martinho and Fátima M. Barreiros
Recycling 2023, 8(1), 12; https://doi.org/10.3390/recycling8010012 - 10 Jan 2023
Cited by 7 | Viewed by 3085
Abstract
The increase in waste has motivated the adoption of the circular economy concept, which assumes particular relevance in the case of plastic materials. This has led to research of new possibilities for recycling plastics after their end-of-life. To achieve this goal, it is [...] Read more.
The increase in waste has motivated the adoption of the circular economy concept, which assumes particular relevance in the case of plastic materials. This has led to research of new possibilities for recycling plastics after their end-of-life. To achieve this goal, it is fundamental to understand how the materials’ properties change after recycling. This study aims to evaluate the thermal and mechanical properties of recycled plastics, namely polycarbonate (PC), polystyrene (PS), glass fibre-reinforced polyamide 6 (PA6-GF30), and polyethylene terephthalate (PET). With this purpose, injected samples were mechanically recycled twice and compared through thermal and mechanical tests, such as differential scanning calorimetry, hardness, tensile strength, and the melt flow rate. The results show that the amorphous materials used do not suffer significant changes in their properties but exhibit changes in their optical characteristics. The semicrystalline ones present some modifications. PET is the material that suffers the biggest changes, both in its flowability and mechanical properties. This work demonstrates that the mechanical recycling process may be an interesting possibility for recycling depending on the desired quality of final products, allowing for some materials to maintain comparable thermal and mechanical properties after going through the recycling process. Full article
(This article belongs to the Special Issue Advances in the Recycling, Processing and Use of Plastic Waste II)
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14 pages, 5539 KiB  
Article
Microstructural and Thermal Behaviour of Composite Material from Recycled Polyethylene Terephthalate and Fly Ash
by Nur Hazzarita Mohd Nasir, Fathoni Usman, Ean Lee Woen, Mohamed Nainar Mohamed Ansari, Abu Bakar Mohd Supian and Saloma Saloma
Recycling 2023, 8(1), 11; https://doi.org/10.3390/recycling8010011 - 9 Jan 2023
Cited by 4 | Viewed by 2355
Abstract
Nowadays, the environmental impact of plastic waste is crucial, and in the energy industry, fly ash, a type of solid waste, has also prompted severe ecological and safety concerns. In this study, we synthesised composite material from two industrial wastes: recycled polyethylene terephthalate [...] Read more.
Nowadays, the environmental impact of plastic waste is crucial, and in the energy industry, fly ash, a type of solid waste, has also prompted severe ecological and safety concerns. In this study, we synthesised composite material from two industrial wastes: recycled polyethylene terephthalate (rPET) as the matrix and fly ash as the filler. The effect of different fly ash loadings on the thermal behaviour and microstructure of the composite material using rPET were evaluated. Various loading amounts of fly ash, up to 68%, were added in the rPET mixtures, and composites were made using a single-threaded bar’s barrel extruder. The feeding zone, compression zone, and metering zone made up the three functional areas of the extruder machine with a single-flighted, stepped compression screw. The composite materials were subjected to DSC and SEM equipped with EDX spectroscopy tests to examine their thermal behaviour and microstructural development. It was found that the thermal behaviour of rPET improved with the addition of fly ash but degraded as the fly ash loading increased to 68%, as confirmed by the DSC study. The composites’ microstructural development revealed an even filler distribution within the polymer matrix. However, when the fly ash loading increased, voids and agglomeration accumulated, affecting the composites’ thermal behaviour. Full article
(This article belongs to the Special Issue Sustainable Materials from Waste and Renewable Sources)
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18 pages, 6312 KiB  
Article
Stabilization of Soft Soil by a Sustainable Binder Comprises Ground Granulated Blast Slag (GGBS) and Cement Kiln Dust (CKD)
by Ruqayah Al-Khafaji, Anmar Dulaimi, Hassnen Jafer, Nuha S. Mashaan, Shaker Qaidi, Zahraa Salam Obaid and Zahraa Jwaida
Recycling 2023, 8(1), 10; https://doi.org/10.3390/recycling8010010 - 8 Jan 2023
Cited by 15 | Viewed by 3345
Abstract
Due to its significant deficiencies such as low permeability, low bearing and shear strength, and excessive compressibility, soft soil is one of the most problematic types of soil in civil engineering and soil stabilization can be considered a suitable technique for pavements. This [...] Read more.
Due to its significant deficiencies such as low permeability, low bearing and shear strength, and excessive compressibility, soft soil is one of the most problematic types of soil in civil engineering and soil stabilization can be considered a suitable technique for pavements. This study investigates the use of ground granulated blast slag (GGBS) and cement kiln dust (CKD) as stabilizers for soft soil. Thus, this study involves two optimization stages; in the first stage, GGBS was incorporated into 0%, 3%, 6%, 9%, and 12% by the weight of cement to obtain the optimal percentage, which was 6%. Then, the optimal GGBS was blended with CKD in a binary system at 0%, 25%, 50%, 75%, and 100% by the dry weight of the soil. The testing program used in this paper was Atterberg limits with compaction parameters to investigate the physical properties and unconfined compressive strength (USC) at 7 and 28 days to examine the mechanical characteristics. In addition, the microstructures of the soil specimens were tested at 7 and 28 days using scanning electron microscopy (SEM). The findings reveal that the binary system enhanced the physical and mechanical properties of the soft soil. The optimum binder achieved in this study was 6% (25% GGBS and 75% CKD), which generates an increase in strength of about 3.3 times in 7 days, and of 5.5 times in 28 days in comparison to the untreated soil. The enhancement was attributed to the formation of the hydration products as approved by SEM. Consequently, in the case of soft subgrade soils, this technique can increase the pavement’s bearing capacity and performance. Full article
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12 pages, 454 KiB  
Article
The Uptake of Recycled Plastic in Manufacturing Companies: A Moral Responsibility or Worthwhile Business Strategy?
by Owais Khan
Recycling 2023, 8(1), 9; https://doi.org/10.3390/recycling8010009 - 7 Jan 2023
Cited by 3 | Viewed by 2787
Abstract
The production and consumption of plastics, which is indispensable in our modern life, has caused severe environmental impacts. Hence, academics and policymakers have been advocating the circularity of plastics. The role of businesses—particularly manufacturing companies—is pivotal to ensuring the circularity of plastics. This [...] Read more.
The production and consumption of plastics, which is indispensable in our modern life, has caused severe environmental impacts. Hence, academics and policymakers have been advocating the circularity of plastics. The role of businesses—particularly manufacturing companies—is pivotal to ensuring the circularity of plastics. This study, therefore, attempted to investigate whether chief executives of manufacturing companies based in the EU are keen on the uptake of recycled plastic and, furthermore, whether the uptake of recycled plastic is a worthwhile business strategy. This study found that the attitude, subjective norms and perceived behavioral control of chief executives positively shape their behavioral intention toward the circularity of plastics. Furthermore, the behavioral intentions of chief executives positively influence the uptake of recycled plastic in manufacturing companies, which could consequently improve business performance. This study suggests measures to increase the uptake of recycled plastic among businesses. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2022)
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20 pages, 8081 KiB  
Article
Upscaling of a Mechanochemical Devulcanization Process for EPDM Rubber Waste from a Batch to a Continuous System
by Larissa Gschwind and Carmen-Simona Jordan
Recycling 2023, 8(1), 8; https://doi.org/10.3390/recycling8010008 - 6 Jan 2023
Cited by 1 | Viewed by 2333
Abstract
The present work is a comparative study of the effects of mechanical shear, temperature, and concentration of a chemical agent on the devulcanization process of post-industrial ethylene propylene diene (EPDM) rubber waste. Devulcanization was carried out in a heating press (no shear), an [...] Read more.
The present work is a comparative study of the effects of mechanical shear, temperature, and concentration of a chemical agent on the devulcanization process of post-industrial ethylene propylene diene (EPDM) rubber waste. Devulcanization was carried out in a heating press (no shear), an internal mixer (low shear), and a co-rotating twin screw extruder (high shear) at temperatures ranging from 100 to 200 °C. The efficiency of pure dibenzamido diphenyl disulfide (DBD) and a commercial devulcanizing agent, Struktol A89®, containing DBD were studied. Based on the results, the devulcanization process was upscaled from 40 g per batch to a continuous process with a capacity of 270 g/h. The parameters were fine-tuned regarding flow rate, screw speed, and temperature. Blends of virgin rubber (VR) and 25, 50, and 75 wt% recyclates were compared with blends of VR and 25, 50, and 75 wt% of untreated RWP. The quality of the recyclate was determined by rheometer tests, SEM images, TGA, and mechanical properties. The best results were obtained with 2 wt% DBD in the extruder with a temperature profile of 120 to 80 °C, 50 rpm, and 4.5 g per minute (gpm). The tensile strength and strain at break of the recyclate already met the requirements of DIN EN 681-1:2006 for the production of sealing systems. The compression set and Shore A hardness were restored by mixing recyclate with 25 wt% VR. Full article
(This article belongs to the Special Issue Recycling of Rubber Waste)
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17 pages, 4676 KiB  
Article
Development and Evaluation of Sustainable Bituminous Paver Blocks
by Padmakumar Radhakrishnan and Vignesh Dhurai
Recycling 2023, 8(1), 7; https://doi.org/10.3390/recycling8010007 - 5 Jan 2023
Viewed by 2567
Abstract
Most road surfaces globally are constructed using bituminous materials. The construction of new roads and the maintenance of existing ones demand a huge amount of virgin natural aggregates. Depletion of resources that takes place during the construction of the road has an impact [...] Read more.
Most road surfaces globally are constructed using bituminous materials. The construction of new roads and the maintenance of existing ones demand a huge amount of virgin natural aggregates. Depletion of resources that takes place during the construction of the road has an impact on cost and also on the environment. Hence, there is a need to reduce virgin aggregate use for bituminous pavement construction. This can be achieved by utilizing sustainable materials such as marble waste and reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA)-type road construction. This research work is focused on sustainable development goal (SDG) 12, exclusively on the target number 12.5 which describes the recycling and reuse of materials. However, no investigations were seen to be reported on the integrated utilization of sustainable materials and RAP in bituminous paver blocks. The bituminous mixes were evaluated based on strength and compared with the control mix in this study. Bituminous paver blocks were then cast using sustainable materials and tested in the laboratory to assess the performance of the blocks through a compression test, Cantabro loss test, and wheel rut test. The test results gave satisfactory values; hence, these bituminous blocks can be used for service maintenance of the pavement structures. The study indicates that using sustainable material along with RAP in blocks can provide an eco-friendly, easily maintainable pavement system which makes it a key approach to SDG 9 as well, in terms of innovative infrastructure solutions. Full article
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20 pages, 2289 KiB  
Article
Release of PAH from Secondary Products Made from End-of-Life Tire Recyclates into 20% Aqueous Ethanol as Assessment of Human Dermal Absorption
by Stefan Hoyer, Lothar Kroll, Benny Fischer, Kai Pisulla and Albrecht Seidel
Recycling 2023, 8(1), 6; https://doi.org/10.3390/recycling8010006 - 30 Dec 2022
Cited by 1 | Viewed by 2195
Abstract
Compliance with the legal limits set at the European level for the content of polycyclic aromatic hydrocarbons (PAH), which are harmful to human health and the environment, is of central importance for the recycling of rubber, particularly end-of-life tires (ELT), into secondary products, [...] Read more.
Compliance with the legal limits set at the European level for the content of polycyclic aromatic hydrocarbons (PAH), which are harmful to human health and the environment, is of central importance for the recycling of rubber, particularly end-of-life tires (ELT), into secondary products, e.g., elastic fall protection mats or anti-slip mats for the transport sector. However, different regulations associated with different analytical methods apply to newly produced tires on the one hand and secondary products made from ELT on the other. Given these discrepancies, ELT can potentially contain levels of PAH, which can be problematic when reused in consumer products. The total PAH content, however, is not without doubt a reliable risk indicator, which should ultimately be based primarily on the transfer of the substances from the product into the skin of human beings or their release into the environment. Accordingly, additional studies are required to determine the extent to which migration-based measurements are more suitable for risk assessment and how the PAH content correlates with migration. Complementing the recently published results of PAH content in different types of ELT, this study investigates the release of PAH for a range of typical secondary materials composed entirely or partly of ELT. In the present study, migration tests with 20% aqueous ethanol were applied, a methodology that has been shown in previous investigations by others to reflect human skin exposure well, and the resulting migration rates of PAH are determined. Full article
(This article belongs to the Special Issue Recycling of Rubber Waste)
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24 pages, 8666 KiB  
Article
Use of Biomass Ash in Reinforced Clayey Soil: A Multiscale Analysis of Solid-State Reactions
by Maximiliano Fastelli, Costanza Cambi, Azzurra Zucchini, Paola Sassi, Elia Pandolfi Balbi, Leonardo Pioppi, Franco Cotana, Gianluca Cavalaglio and Paola Comodi
Recycling 2023, 8(1), 5; https://doi.org/10.3390/recycling8010005 - 29 Dec 2022
Cited by 1 | Viewed by 1983
Abstract
Clayey soils are treated with binding agents to improve their mechanical properties, as these soils are widely used in construction. The production of binding agents is an energy-intensive process and emits significant amounts of CO2. In addition, the interest in recycling [...] Read more.
Clayey soils are treated with binding agents to improve their mechanical properties, as these soils are widely used in construction. The production of binding agents is an energy-intensive process and emits significant amounts of CO2. In addition, the interest in recycling industry waste materials has increased, and the management of significant waste from biomass power plants remains an issue. We used three biomass ashes derived from pellet, olive, and grapevine combustion as stabilizing agents of a clayey soil. The mechanical effects of the treatment on clay-ash mixtures were evaluated using confined compressive tests. The mixtures’ chemo-mineralogical evolution was evaluated through X-ray powder diffraction and quantitative Rietveld analysis, Fourier transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy coupled with scanning electron microscopy (EDS-SEM). The FT-IR spectra showed an evolution of the Si-O-Si/Al features, with shifting band positions due to polymerization of the tetrahedral units. The EDS-SEM analysis showed an evolution of the Ca/Si distribution and the growth of pozzolanic reaction products, such as C-S-H nanocrystals and gels. This evidence confirms that the pozzolanic reaction occurs by dissolution of clay minerals and/or the amorphous phase of the ash, which affects the macroscopic behavior of clayey soils in terms of stiffening and strengthening, as confirmed by mechanical tests, albeit these effects are non-homogenous and continuous. Full article
(This article belongs to the Special Issue Sustainable Materials from Waste and Renewable Sources)
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18 pages, 2659 KiB  
Article
An Analysis of the Circular Economy Practices of Pesticide Container Waste in Pakistan
by Ali Raza, Syed Asif Ali Naqvi, Muhammad Abuzar Mehdi, Muhammad Usman, Sadia Ali, Ashfaq Ahmad Shah and Bilal Hussain
Recycling 2023, 8(1), 4; https://doi.org/10.3390/recycling8010004 - 27 Dec 2022
Cited by 3 | Viewed by 2695
Abstract
Empty pesticide container recycling helps control nonpoint source pollution and provides alternative sources for basic materials. This article investigates end users’ adoption of recycling their pesticide container waste and investigates the determinants influencing their adoption. The study uses an extensive farm survey of [...] Read more.
Empty pesticide container recycling helps control nonpoint source pollution and provides alternative sources for basic materials. This article investigates end users’ adoption of recycling their pesticide container waste and investigates the determinants influencing their adoption. The study uses an extensive farm survey of 210 farmers from the District Faisalabad of the Province of Punjab (Pakistan). It applies the partial least squares structural equation modeling technique to assess the impact of different elements, such as subjective norms, attitude, perceived behavioral control, intention, and environmental concerns, on end users’ adoption regarding recycling of pesticide empty container waste. The results explain that perceived behavioral control and intention to reuse pesticide container waste positively predict end users’ adoption. Furthermore, adoption is positively impacted by attitude, subjective norms, and environmental concerns via the intention to recycle pesticide container waste. The study urges the need to encourage end users to share responsibility for pesticide container waste management for a sustainable society. Full article
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8 pages, 925 KiB  
Article
Biological Pretreatment Effects on the Bioconversion of Brewer Spent Grain with Hermetia illucens Larvae
by Martha Sumba-Zhongor, Eduardo Álava, Luis Galarza, Johana Ortiz-Ulloa, Eduardo J. Chica, Omar Ruiz-Barzola, Julia Nieto-Wigby, Maria Isabel Jiménez-Feijoo and Malena Torres-Ulloa
Recycling 2023, 8(1), 3; https://doi.org/10.3390/recycling8010003 - 27 Dec 2022
Cited by 1 | Viewed by 2183
Abstract
Hermetia illucens is an important species for waste management and the circular economy. The aim of this study was to analyze the effects of Trichoderma reesei C2A and Pleurotus sp. as pretreatments of brewer spent grain (BSG). BSG was inoculated with fungal solution [...] Read more.
Hermetia illucens is an important species for waste management and the circular economy. The aim of this study was to analyze the effects of Trichoderma reesei C2A and Pleurotus sp. as pretreatments of brewer spent grain (BSG). BSG was inoculated with fungal solution or distilled water (control). After seven days, this was used for H. illucens larvae cultivation. At the end of bioconversion process, parameters of substrate reduction and H. illucens larval development were evaluated. Chemical properties of BSG, frass and larvae were also analyzed. With T. reesei C2A pretreatment, highest substrate reduction (46.3 ± 0.9%) was achieved, but larval growth rate was lower (1.0 ± 0.1 mg/d) than that of control (2.8 ± 0.2 mg/d). Larvae of Pleurotus sp. pretreatment had limited development, reflected in their negative growth rate (−0.6 ± 0.2 mg/d). In conclusion, cultivation of H. illucens larvae (six day old) on BSG pretreated with Pleurotus sp. is not recommended. On the other hand, T. reesei C2A pretreatment enhance BSG reduction, and its potential use for lignocellulosic waste management should be more explored. Full article
(This article belongs to the Topic Solid Waste Management)
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17 pages, 7861 KiB  
Article
Blending Recycled High-Density Polyethylene HDPE (rHDPE) with Virgin (vHDPE) as an Effective Approach to Improve the Mechanical Properties
by Jian Zhang, Valerian Hirschberg and Denis Rodrigue
Recycling 2023, 8(1), 2; https://doi.org/10.3390/recycling8010002 - 26 Dec 2022
Cited by 13 | Viewed by 6487
Abstract
The mechanical properties of virgin/recycled high-density polyethylene (HDPE) blends over the complete concentration range was thoroughly investigated in this work. In particular, a focus was made on the long-term properties via mechanical fatigue. Two different mixing methods, namely powder mixing (dry blending) and [...] Read more.
The mechanical properties of virgin/recycled high-density polyethylene (HDPE) blends over the complete concentration range was thoroughly investigated in this work. In particular, a focus was made on the long-term properties via mechanical fatigue. Two different mixing methods, namely powder mixing (dry blending) and extrusion mixing (melt blending), were used to determine the effect of processing conditions on the tensile and fatigue behavior of the blends after compression molding. It was found that both tensile (modulus, ultimate strength) and fatigue performances were improved with increasing vHDPE content. Based on the obtained data, a correlation between the blends composition and mechanical properties is reported. Moreover, it was observed that increasing the vHDPE content led to slower crack propagation rate, probably due to less defects (contamination) in the blends. Finally, a negligible difference in mechanical properties (fatigue resistance) between both mixing approaches was observed, but samples produced via powder mixing showed less viscous dissipation (heat generation) as the vHDPE content increased, leading to lower surface temperature rise which can be an advantage for specific applications. Full article
(This article belongs to the Special Issue Advances in the Recycling, Processing and Use of Plastic Waste II)
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12 pages, 1616 KiB  
Article
The Potential of Valorized Sisal Decorticated Waste in Rearing of Black Soldier Fly
by Aziza Athumani Konyo, Revocatus Machunda, Liliane Pasape and Anthony Mshandete
Recycling 2023, 8(1), 1; https://doi.org/10.3390/recycling8010001 - 23 Dec 2022
Viewed by 2458
Abstract
The use of sisal decorticated waste (SDW) for various applications is limited due to its high acidic content. This is the first study of its kind regarding the use of SDW as a substrate for the growth of the black soldier fly (BSF). [...] Read more.
The use of sisal decorticated waste (SDW) for various applications is limited due to its high acidic content. This is the first study of its kind regarding the use of SDW as a substrate for the growth of the black soldier fly (BSF). Pre-treatment was a necessary and challenging step performed on the waste to meet the minimum requirements for the rearing of BSF. The SDW was sun dried, sieved, and decomposited and neutralized to form the final products that were used for the rearing of BSF. The resultant waste had fourteen (14) elements; the essential elemental form results were Ca, P, K, Mn, Fe, Cu, and Zn at varying levels, which are all essential for animal growth. The SDW contained 10 ± 0.01 percent of crude protein, 11 ± 0.02 moisture and energy (1615 kcal/g of sisal decorticated waste). The sun dried BSF larvae were reared on SDW that contained 53 ± 0.005 percent of crude protein, 4 ± 0.01 percent of crude fat, a moisture content of (10 ± 0.1)%, carbohydrate percent of (43 ± 0.01)%, and ash percent of (37 ± 0.08). When rearing was finished, 3000 g of dried pre-treated waste yielded more wet BSF larvae, (336 ± 41.3) g, compared to 3000 g of fruit waste, which yielded (244 ± 4.16) g of wet BSF larvae. Therefore, based on this study, SDW is a promising potential feed for rearing BSF because it had a better reduction of the waste by 52%. Furthermore, the harvested BSF larvae contained sufficient nutritional value to feed poultry and fish. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials II)
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