Recycling

13 pages, 1178 KiB

Open AccessArticle

Assessment of Three Recycling Pathways for Waste Cooking Oil as Feedstock in the Production of Biodiesel, Biolubricant, and Biosurfactant: A Multi-Criteria Decision Analysis Approach

by Giovanni De Feo, Carmen Ferrara, Luana Giordano and Libero Sesti Ossèo

Recycling 2023, 8(4), 64; https://doi.org/10.3390/recycling8040064 - 20 Aug 2023

Cited by 2 | Viewed by 2797

Abstract

The management of waste cooking oil (WCO) often poses significant challenges. The improper disposal of WCO results in negative environmental impacts and economic losses. However, from a circular economy perspective, WCO can be recycled and used as a sustainable feedstock for numerous industrial [...] Read more.

The management of waste cooking oil (WCO) often poses significant challenges. The improper disposal of WCO results in negative environmental impacts and economic losses. However, from a circular economy perspective, WCO can be recycled and used as a sustainable feedstock for numerous industrial products, replacing virgin vegetable oils. This approach enables the recovery of resources while simultaneously addressing the problem of WCO disposal. By employing a multi-criteria decision analysis (MCDA) approach, the study assesses three alternative recycling pathways for WCO used as a feedstock in the production of (A1) biodiesel, (A2) biolubricant, and (A3) biosurfactant. The aim is to identify the optimal alternative, taking into account environmental, economic, and technical factors. The procedure involved a team of chemical engineers working in the WCO recycling sector who were selected as decision makers. The ‘priority scale’ combined with the Paired Comparison Technique was employed as a weighting method to evaluate the selected criteria. The results revealed that the decision makers considered environmental sustainability as the most crucial evaluation criterion, followed by the economic criterion. In contrast, the aspect of process management was deemed less significant. Among the compared alternatives, utilizing WCO as a feedstock for biosurfactant production was assessed as the optimal WCO recycling solution. This alternative not only demonstrated the lowest coefficient variation but was also deemed the most favourable option. Biolubricant production was determined to be the second-best alternative. The adopted MCDA approach proved to be a reliable and effective tool, enabling the clear identification of the preferred WCO recycling alternative among those assessed. This was achieved through the utilization of the decision makers’ expertise and knowledge. Full article

(This article belongs to the Special Issue Feature Papers in Recycling 2023)

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14 pages, 2783 KiB

Open AccessArticle

Catalytic Pyrolysis of Waste Low-Density Polyethylene (LDPE) Carry Bags to Fuels: Experimental and Exergy Analyses

by Krishna Prasad Rajan, Ibrahim Mustafa, Aravinthan Gopanna and Selvin P. Thomas

Recycling 2023, 8(4), 63; https://doi.org/10.3390/recycling8040063 - 16 Aug 2023

Cited by 1 | Viewed by 2918

Abstract

The present investigation reports the results of experiments related to the conversion of low-density polyethylene (LDPE) waste carry bags to fuel through an economic catalytic pyrolysis method in a batch reactor using zinc oxide (ZnO) as the catalyst. Plastics are highly beneficial for [...] Read more.

The present investigation reports the results of experiments related to the conversion of low-density polyethylene (LDPE) waste carry bags to fuel through an economic catalytic pyrolysis method in a batch reactor using zinc oxide (ZnO) as the catalyst. Plastics are highly beneficial for the day-to-day activities of human beings; however, their decomposition is limited due to their strong covalent bonding. Degradation of these big molecules into smaller ones or monomers has been attempted by several researchers in recent decades, with limited success. Pyrolysis is one of the ideas used to convert plastics, with the crowded structure of polymers, into fuel rather than small molecules. Among these plastics, LDPE is widely used as carry bags throughout the world, and, herein, the results of catalytic pyrolysis of the conversion of LDPE into fuel are reported. A compact laboratory-scale batch reactor, specially designed at our laboratory, was used to carry out the pyrolysis process. Different dosages of ZnO were used as a catalyst to carry out the pyrolysis at a specific temperature. The optimal dosage of ZnO for a 50 g waste LDPE batch was found to be 0.6 g to get the maximum oil yield. The yielded oil was analyzed chemically through Fourier transform infrared spectroscopy (FTIR) and a Reformulyzer M4 Hydrocarbon Group Type Analyzer. Evaluation of physical and chemical exergy along with exergetic efficiency of the process was carried out. The described experiments and the results represent a small but significant step toward curbing the menace of plastic solid wastes, which are degrading the environment and human life worryingly, and allowing them to be utilized for generating low-cost fuel for transportation and other applications. Full article

(This article belongs to the Special Issue Sustainable Materials from Waste and Renewable Sources)

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12 pages, 1812 KiB

Open AccessArticle

Recycling of Polypropylene Recovered from a Composting Plant: Mechanical Behavior of Compounds with Virgin Plastic

by Claudio Badini, Oxana Ostrovskaya, Giulia Bernagozzi, Roberta Lanfranco and Stefania Miranda

Recycling 2023, 8(4), 62; https://doi.org/10.3390/recycling8040062 - 31 Jul 2023

Cited by 2 | Viewed by 1889

Abstract

The recycling of polypropylene recovered from waste discarded by a composting plant was investigated. The recovery involved a sorting step carried out by means of an optical infrared separator and a subsequent washing treatment. This method of processing allowed us to obtain polypropylene [...] Read more.

The recycling of polypropylene recovered from waste discarded by a composting plant was investigated. The recovery involved a sorting step carried out by means of an optical infrared separator and a subsequent washing treatment. This method of processing allowed us to obtain polypropylene that was only slightly contaminated by other polymeric and inorganic materials. As many tens of tons of polypropylene could be recovered every year in this plant, recycling could be convenient from the economic point of view and beneficial for the protection of the environment. In fact, the landfill of this waste could be reduced in this manner. A possible mechanical recycling route was developed for the recovered plastic. The recycling was carried out by pelletizing the recovered polypropylene, mixing it with a commercial polypropylene feedstock, and manufacturing items by injection molding. In this way, tensile specimens containing different amounts of recycled polypropylene were processed and tested. Their tensile features were compared with those of a commercial polypropylene that was used as a reference. The elastic modulus and tensile strength were slightly worsened when using the recycled plastic, while the strain at failure significantly increased. Nonetheless, the tensile properties of compounds made by mixing recycled and virgin polypropylene were consistent with the characteristics that are expected for polypropylene-based plastics. Full article

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46 pages, 1892 KiB

Open AccessReview

Lignocellulosic Agricultural Waste Valorization to Obtain Valuable Products: An Overview

by Alessandro Blasi, Alessandra Verardi, Catia Giovanna Lopresto, Sarah Siciliano and Paola Sangiorgio

Recycling 2023, 8(4), 61; https://doi.org/10.3390/recycling8040061 - 20 Jul 2023

Cited by 18 | Viewed by 7122

Abstract

The sustainable management of lignocellulosic agricultural waste has gained significant attention due to its potential for the production of valuable products. This paper provides an extensive overview of the valorization strategies employed to convert lignocellulosic agricultural waste into economically and environmentally valuable products. [...] Read more.

The sustainable management of lignocellulosic agricultural waste has gained significant attention due to its potential for the production of valuable products. This paper provides an extensive overview of the valorization strategies employed to convert lignocellulosic agricultural waste into economically and environmentally valuable products. The manuscript examines the conversion routes employed for the production of valuable products from lignocellulosic agricultural waste. These include the production of biofuels, such as bioethanol and biodiesel, via biochemical and thermochemical processes. Additionally, the synthesis of platform chemicals, such as furfural, levulinic acid, and xylose, is explored, which serve as building blocks for the manufacturing of polymers, resins, and other high-value chemicals. Moreover, this overview highlights the potential of lignocellulosic agricultural waste in generating bio-based materials, including bio-based composites, bio-based plastics, and bio-based adsorbents. The utilization of lignocellulosic waste as feedstock for the production of enzymes, organic acids, and bioactive compounds is also discussed. The challenges and opportunities associated with lignocellulosic agricultural waste valorization are addressed, encompassing technological, economic, and environmental aspects. Overall, this paper provides a comprehensive overview of the valorization potential of lignocellulosic agricultural waste, highlighting its significance in transitioning towards a sustainable and circular bioeconomy. The insights presented here aim to inspire further research and development in the field of lignocellulosic waste valorization, fostering innovative approaches and promoting the utilization of this abundant resource for the production of valuable products. Full article

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4 pages, 182 KiB

Open AccessEditorial

Special Issue “Feature Papers in Recycling 2022”

by Francesco Paolo La Mantia and Beatrice Castellani

Recycling 2023, 8(4), 60; https://doi.org/10.3390/recycling8040060 - 13 Jul 2023

Viewed by 1137

Abstract

This Special Issue aimed to collect high-quality papers (original research articles or comprehensive review papers) published during 2022 on the subject of waste recycling [...] Full article

(This article belongs to the Special Issue Feature Papers in Recycling 2022)

19 pages, 26489 KiB

Open AccessArticle

The Recycling of End-of-Life Lithium-Ion Batteries and the Phase Characterisation of Black Mass

by Laurance Donnelly, Duncan Pirrie, Matthew Power, Ian Corfe, Jukka Kuva, Sari Lukkari, Yann Lahaye, Xuan Liu, Quentin Dehaine, Ester M. Jolis and Alan Butcher

Recycling 2023, 8(4), 59; https://doi.org/10.3390/recycling8040059 - 12 Jul 2023

Cited by 1 | Viewed by 5265

Abstract

Black mass is the industry term applied to end-of-life (EoL) lithium-ion batteries that have been mechanically processed for potential use as a recycled material to recover the valuable metals present, including cobalt, lithium, manganese, nickel and copper. A significant challenge to the effective [...] Read more.

Black mass is the industry term applied to end-of-life (EoL) lithium-ion batteries that have been mechanically processed for potential use as a recycled material to recover the valuable metals present, including cobalt, lithium, manganese, nickel and copper. A significant challenge to the effective processing of black mass is the complexity of the feed material. Two samples of black mass from a European source were analysed using a combination of methods including automated SEM-EDS (AMICS) to characterise and quantify the phases present and particle chemistry. Micro X-CT imaging, overlain onto automated mineralogy images, enabled the 3D morphology of the particles to be determined. Micro-XRF was used to map the copper, nickel, manganese and cobalt-bearing phases. Since Li cannot be detected using SEM-EDS, its abundance was semi-quantified using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The integration of these complimentary analytical methods allowed for detailed phase characterisation, which may guide the potential hydrometallurgical or pyrometallurgical recycling routes and chemical assaying. Full article

(This article belongs to the Special Issue Recycling of Spent Batteries—Trash to Treasure)

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18 pages, 1795 KiB

Open AccessArticle

Assessing the Measurement Model for Source-Separating Waste for Recycling under a Proposed Smart Waste Management Scheme in Shah Alam, Malaysia

by Abdullatif Bazrbachi, Shaufique Fahmi Sidique, Shehu Usman Adam, Normaz Wana bt Ismail and Tey Yeong Sheng

Recycling 2023, 8(4), 58; https://doi.org/10.3390/recycling8040058 - 07 Jul 2023

Cited by 1 | Viewed by 1683

Abstract

Due to rapid urbanization, solid waste management (SWM) is a major challenge in Malaysia, hence the need to sustainably manage it. Compared with other states, Selangor produces the highest volume of domestic waste. Most of the state’s waste is generated in Shah Alam [...] Read more.

Due to rapid urbanization, solid waste management (SWM) is a major challenge in Malaysia, hence the need to sustainably manage it. Compared with other states, Selangor produces the highest volume of domestic waste. Most of the state’s waste is generated in Shah Alam City. This condition is expected to worsen because the population of Shah Alam is projected to rise by 2.5% from 2018 to 2035. This situation will increase the demand for resources, production, and consumption, increasing the volume of waste generated in Shah Alam. Hence, the pressing necessity to advance from the current traditional waste management practices to a more sustainable SWM system has been identified as a key target in Shah Alam’s 2025–2030 plans. The Smart Waste Management System (SWMS) has been identified as a novel approach to dealing with the absence of route optimization, real-time information exchange, and the consequent increase in waste management costs. All of these elements have characterized the current traditional households’ SWM. However, because this method is novel, there is a dearth of knowledge on the appropriate measurement model for evaluating the dimension of households’ intention to recycle waste through source separation as well as measuring the determinants of such a pro-environmental intention under the new SWMS. Thus, confirmatory factor analysis (CFA) was carried out to verify the factorial structure of the variables, relying on the Theory of Planned Behavior (TPB) based on the structural dimensions identified in prior exploratory factor analysis (EFA). The study found support for the use of TPB as a relevant framework for modeling the intention for source separation and its determinants under SWMS. Full article

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17 pages, 1428 KiB

Open AccessArticle

Evaluation of Biogas Energy from Co-Digestion of Organic Urban Solid Waste with Lime Mud

by Ulisses Raad da Silva Coelho, Adriele Maria de Cássia Crispim, Maria Auxiliadora de Barros Martins, Regina Mambeli Barros, Maria Luiza Grillo Reno, Geraldo Lúcio Tiago Filho and Ivan Felipe Silva Santos

Recycling 2023, 8(4), 57; https://doi.org/10.3390/recycling8040057 - 01 Jul 2023

Viewed by 1886

Abstract

The elevated presence of organic material in Brazilian urban solid waste, along with mismanagement of its disposal, can aggravate environmental problems from greenhouse gas emissions to water and soil pollution. In parallel, the paper and cellulose industries consume considerable resources and produce important [...] Read more.

The elevated presence of organic material in Brazilian urban solid waste, along with mismanagement of its disposal, can aggravate environmental problems from greenhouse gas emissions to water and soil pollution. In parallel, the paper and cellulose industries consume considerable resources and produce important solid wastes, including lime mud. These urban and industrial realities present common ground, from which a little-studied alternative arises in using biogas electrical energy from the co-digestion of the organic portion of urban solid waste using lime mud. This intersection can reduce the environmental impacts associated with inadequate management and disposal of solid waste, providing industry financial economy resources and contributing to Brazilian energy grid diversification. The current study used economic–financial indicators to evaluate the proposal’s economic feasibility. The obtained results presented a minimum population of 165,200 inhabitants, generating 39,295.77 m³/year of methane, in order to enable a co-digestion proposal. The sensitivity analysis indicated that a population of 185,500 inhabitants would provide a 10-year payback, an energy rate of USD 0.139, and 44,124.49 m³/year of methane to supply the population with power. The net present value was USD 23,336.94, with an internal return rate of 14.71% and a levelized energy cost of 0.103 USD/kWh. Full article

(This article belongs to the Special Issue Sustainable Recycling of Municipal Solid Waste)

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21 pages, 2612 KiB

Open AccessArticle

Sustainable Waste Management for Clean and Safe Environments in the Recreation and Tourism Sector: A Case Study of Lithuania, Turkey and Morocco

by Dalia Perkumienė, Ahmet Atalay, Larbi Safaa and Jurgita Grigienė

Recycling 2023, 8(4), 56; https://doi.org/10.3390/recycling8040056 - 28 Jun 2023

Cited by 9 | Viewed by 19784

Abstract

Due to intensive tourism and increasing demand for recreational activities, people produce more waste. In this context, the aim of this research is to determine the opinions of experts working in tourism and recreation areas in Lithuania, Turkey and Morocco with respect to [...] Read more.

Due to intensive tourism and increasing demand for recreational activities, people produce more waste. In this context, the aim of this research is to determine the opinions of experts working in tourism and recreation areas in Lithuania, Turkey and Morocco with respect to waste management problems. Interviews were held in Turkey, Lithuania and Morocco in order to determine the attitudes of experts about recreational activities with respect to a clean environment and sustainability. A semistructured interview form was used for interviews with forest operators and other experts. The sample group consisted of 24 experts from Turkey, Lithuania and Morocco. The prominent results of the interviews conducted in the three countries regarding waste and sustainable waste management can be listed as follows: intensive waste production caused by participants, inadequate legal regulation, insufficient recycling, damage to the environment and natural structures, inadequate control and inspections, lack of education and awareness activities, an insufficient number of personnel and insufficient infrastructure. Sustainable waste management strategies, such as reducing waste generation, improving waste collection and disposal methods, and promoting recycling and composting, can help to mitigate these negative impacts. Full article

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23 pages, 511 KiB

Open AccessArticle

The Impact of Industry 4.0 on the Steel Sector: Paving the Way for a Disruptive Digital and Ecological Transformation

by Laura Tolettini and Eleonora Di Maria

Recycling 2023, 8(4), 55; https://doi.org/10.3390/recycling8040055 - 28 Jun 2023

Cited by 2 | Viewed by 2421

Abstract

Since the creation of a common term to indicate a set of incremental and disruptive digital technologies, Industry 4.0 has challenged European manufacturers to find a way to concretely exploit these innovations in their own business strategy. During this journey, Industry 4.0 has [...] Read more.

Since the creation of a common term to indicate a set of incremental and disruptive digital technologies, Industry 4.0 has challenged European manufacturers to find a way to concretely exploit these innovations in their own business strategy. During this journey, Industry 4.0 has recently highlighted some evidence about its efficacy in enabling strategic goals on the three dimensions (economical, environmental, social) of sustainable development, which is a key element for the European Union’s goal to make manufacturers become carbon neutral until 2030. Industry 4.0 and sustainability are together affecting manufacturers’ business models, forcing managers to take chances and face challenges within their organization and in their supply-chain. As an energy-intensive sector, steel industries will be intensively affected by sustainability paradigms. With 19 qualitative interviews in the organization and supply chain of an internationalized steel producer, Feralpi Group, we provide evidence that, beyond the use of main strategic technologies (Internet of Things and Big Data analysis), the implementation of a sustainability strategy is also possible through the creation of new partnerships beyond the own supply chain. The combination of Industry 4.0 technologies and sustainability strategies, especially concerning the environment through Circular Economy practices, pushes steel industries to revise their business models, paving the way for unexpected collaborations, where suppliers, customers, and even more diverse stakeholders such as competitors could bring benefits to the company sustainable economic growth and durability. Full article

(This article belongs to the Special Issue Circular Economy in Europe: Governance, Economics and Industrial Strategy)

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14 pages, 3428 KiB

Open AccessArticle

Recycled Construction and Demolition Waste as Supplementary Cementing Materials in Eco-Friendly Concrete

by Silvina V. Zito, Edgardo F. Irassar and Viviana F. Rahhal

Recycling 2023, 8(4), 54; https://doi.org/10.3390/recycling8040054 - 28 Jun 2023

Cited by 1 | Viewed by 1578

Abstract

Growing environmental awareness and scarcity of natural resources are forcing the world to migrate from linear to circular economies. The possibility of partially replacing cement with ceramic-based waste from construction and demolition waste (C&DW) is a government and industry focus. The present study [...] Read more.

Growing environmental awareness and scarcity of natural resources are forcing the world to migrate from linear to circular economies. The possibility of partially replacing cement with ceramic-based waste from construction and demolition waste (C&DW) is a government and industry focus. The present study analyzes the effects of including finely ground complete walls of ceramic blocks (including masonry mortars) as supplementary cementing materials (SCM) on the physical, mechanical, and transport properties (water absorption and permeability) of concrete. The replacement ratio employed was 25% by weight of cement. Studies of the hydration evolution of cement pastes support the described properties of concretes. The findings reveal that the ground ceramic-based waste from C&DW stimulates hydration at all ages. Initially, this stimulation is predominantly physical (filler effect), but in later stages, it becomes chemical (pozzolanic reaction). Based on the results obtained in this study, it is possible to produce concrete with mechanical properties comparable to those of conventional concrete at 28 days. Full article

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18 pages, 1973 KiB

Open AccessReview

Carbon-Based Synthesized Materials for CO₂ Adsorption and Conversion: Its Potential for Carbon Recycling

by Tuan-Dung Hoang, Suhaib A. Bandh, Fayaz A. Malla, Irteza Qayoom, Shahnaz Bashir, Suhail Bashir Peer and Anthony Halog

Recycling 2023, 8(4), 53; https://doi.org/10.3390/recycling8040053 - 21 Jun 2023

Cited by 2 | Viewed by 4438

Abstract

During the last half-century, the CO₂ concentration in the world’s atmosphere has increased from 310 p.p.m. to over 380 p.p.m. This is due to the widespread usage of fossil fuels as a main source of energy. Modeling forecasts have shown that this trend will [...] Read more.

During the last half-century, the CO₂ concentration in the world’s atmosphere has increased from 310 p.p.m. to over 380 p.p.m. This is due to the widespread usage of fossil fuels as a main source of energy. Modeling forecasts have shown that this trend will continue to rise and reducing CO₂ emissions is a challenging task for multi-stakeholders, including research institutions. The UN Climate Change Conference in Glasgow (COP26) has stressed that stakeholders need to work together to achieve a NetZero target. Technologies involving absorbents for the capture of CO₂ from a gas mixture are energy-intensive. Carbon adsorption and conversion (CAC) approaches have been gaining attention recently since these technologies can mitigate CO₂ emissions. In this review, materials ranging from advanced carbon-based materials to natural resources-based materials will be reviewed. Adsorption and conversion capacities as well as the scalability possibility of these technologies for solving the CO₂ emission problem will be investigated. The review, therefore, is timely and meaningful concerning the net zero emission targets set by countries and developmental organizations worldwide. Full article

(This article belongs to the Special Issue Featured Reviews in Recycling)

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Recycling, Volume 8, Issue 4 (August 2023) – 12 articles

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