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19 pages, 7696 KiB

Open AccessArticle

Hyperspectral Imaging for Detecting Plastic Debris on Shoreline Sands to Support Recycling

by Roberta Palmieri, Riccardo Gasbarrone, Giuseppe Bonifazi, Giorgia Piccinini and Silvia Serranti

Appl. Sci. 2024, 14(23), 11437; https://doi.org/10.3390/app142311437 - 9 Dec 2024

Cited by 1 | Viewed by 1228

Abstract

Environmental pollution from plastic debris is raising concerns not only for the vulnerability of marine species to ingestion but also for potential human health hazards posed by small particles, known as microplastics. In this context, marine areas suffer from a lack of constant [...] Read more.

Environmental pollution from plastic debris is raising concerns not only for the vulnerability of marine species to ingestion but also for potential human health hazards posed by small particles, known as microplastics. In this context, marine areas suffer from a lack of constant shoreline cleanups to remove accumulated debris, preventing their degradation and fragmentation. To establish optimal strategies for streamlining plastic recovery and recycling operations, it is important to have a system for recognizing plastic debris on the beach and, more specifically, for identifying the type of polymer and mapping (e.g., topologically assessing) the distribution of plastic debris on shoreline sands. This study aims to provide an operative tool finalized to perform an in situ detection, analysis, and characterization of plastic debris present in the coastal environment (i.e., beaches), adopting a near-infrared (NIR)-based hyperspectral imaging (HSI) approach. In more detail, the possibility of identifying and classifying polymers of plastic debris by NIR-HSI in three different areas along the Pontine coastline of the Lazio region (Latina, Italy) was investigated. The study focused on three distinct beaches (i.e., Foce Verde, Capo Portiere, and Sabaudia), each characterized by a different type of sand. For each location, the adopted approach allowed for the systematic classification of the various types of plastic waste found. Three Partial Least Squares Discriminant Analysis (PLS-DA) classification models were developed using a cascade detection strategy. The first model was designed to distinguish plastics from other materials in sand samples, the second to detect plastic particles in the sand, and the third to classify the type of polymer composing each identified plastic particle. Obtained results showed that, on the one hand, plastics were correctly detected from sand and other materials (i.e., sensitivity = 0.892–1.000 and specificity = 0.909–0.996), and on the other, the recognition of polymer type was satisfactory, according to the performance statistical parameters (i.e., sensitivity = 1.000 and specificity = 0.991–1.000). This research highlights the potential of the NIR-HSI approach as a reliable, non-invasive method for plastic debris monitoring and polymer classification. Its scalability and adaptability suggest possible future integration into mobile systems, enabling large-scale monitoring and efficient debris management. Full article

(This article belongs to the Special Issue Research Progress in Waste Resource Utilization)

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24 pages, 8805 KiB

Open AccessArticle

Alternative Sources of Raw Materials for the Ceramic Industry through Granite Waste Recycling: A Case Study from Buddusò, Sardinia, Italy

by Carmela Vaccaro, Antonello Aquilano and Elena Marrocchino

Appl. Sci. 2024, 14(17), 7967; https://doi.org/10.3390/app14177967 - 6 Sep 2024

Cited by 1 | Viewed by 1351

Abstract

The sourcing of raw materials is becoming an increasingly concerning issue for the European Union, which is adopting a series of strategies aimed at mitigating the dependence on third countries for procurement. The supply of feldspars, for instance, which is significant within the [...] Read more.

The sourcing of raw materials is becoming an increasingly concerning issue for the European Union, which is adopting a series of strategies aimed at mitigating the dependence on third countries for procurement. The supply of feldspars, for instance, which is significant within the ceramic industry, raises concerns due to heavy reliance on third countries. Therefore, it is imperative to identify potential alternative sources for procurement, including the recycling of waste from the extraction of ornamental granite rocks enriched in such minerals. The Sardinia region in Italy, once a global leader in granite extraction, has now witnessed a significant reduction in production due to intense competition worldwide, resulting in severe economic repercussions. Additionally, traces of this period remain in the territory in the form of enormous quantities of extraction waste, defacing the landscape and posing potential environmental issues. This study is part of a broader research initiative aimed at identifying a physical process to concentrate rare earth element (REE) minerals from granite waste in a quarry located in Buddusò, Sardinia. The specific objective of this study is to analyze the whole rock composition, crushing powder, and the diamagnetic by-products generated by gravity and magnetic separations to identify potential applications for their use. Full article

(This article belongs to the Special Issue Research Progress in Waste Resource Utilization)

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16 pages, 3884 KiB

Open AccessArticle

A Novel Technosol Formulation for Sustainable Landfill Top Covers Using Non-Hazardous Wastes

by Juan Carlos Fernández-Caliani, Julia Álvarez-Lozano, Encarnación García-Navarro, Sandra Fernández-Landero, Cristóbal Cantero and María Inmaculada Giráldez

Appl. Sci. 2024, 14(14), 6166; https://doi.org/10.3390/app14146166 - 15 Jul 2024

Cited by 1 | Viewed by 1308

Abstract

This study explores the potential of non-hazardous wastes for crafting an engineered soil-like material (Technosol) suitable for landfill capping applications. Three distinct materials—waste foundry sand (WFS), washing aggregate sludge (WAS), and composted biosolids (CBS)—were strategically combined to develop this innovative Technosol. The formulation [...] Read more.

This study explores the potential of non-hazardous wastes for crafting an engineered soil-like material (Technosol) suitable for landfill capping applications. Three distinct materials—waste foundry sand (WFS), washing aggregate sludge (WAS), and composted biosolids (CBS)—were strategically combined to develop this innovative Technosol. The formulation process involved a comprehensive analysis of their physical–chemical properties, mineral composition, leachate quality, and a series of geotechnical assessments to ensure compliance with landfill top cover construction standards. The blend 90WFS/10WAS showed optimal geotechnical properties for constructing a protective layer, including maximum dry density (1.77 g cm⁻³), void ratio (0.4), CBR index (23.2), cohesive strength (40 kPa), internal friction (ϕ = 30°), and permeability coefficient (k = 1.48 × 10⁻⁶ cm s⁻¹). Further enhancement was achieved by adding 10% CBS, resulting in the development of a functional organo-mineral topsoil horizon (81WFS/9WAS/10CBS). Importantly, leachate analysis confirmed the negligible environmental footprint of this Technosol. Moreover, a pot-based experiment with Brassica juncea planting validated its capacity to support plant growth and establish a vegetative cover on the landfill surface. Full article

(This article belongs to the Special Issue Research Progress in Waste Resource Utilization)

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23 pages, 14137 KiB

Open AccessArticle

Steam Explosion-Based Method for the Extraction of Cellulose and Lignin from Rice Straw Waste

by Víctor M. Serrano-Martínez, Henoc Pérez-Aguilar, María Pilar Carbonell-Blasco, Francisca Arán-Ais and Elena Orgilés-Calpena

Appl. Sci. 2024, 14(5), 2059; https://doi.org/10.3390/app14052059 - 1 Mar 2024

Cited by 11 | Viewed by 4218

Abstract

This paper focuses on the optimisation of an efficient extraction process for cellulose and lignin from rice straw waste from the Albufera of Valencia using the steam explosion method. This method is particularly pertinent given the environmental and economic challenges posed by the [...] Read more.

This paper focuses on the optimisation of an efficient extraction process for cellulose and lignin from rice straw waste from the Albufera of Valencia using the steam explosion method. This method is particularly pertinent given the environmental and economic challenges posed by the current disposal practices of agricultural waste. The technique comprises a high-temperature cooking stage followed by instantaneous decompression, effectively altering the biomass’s physical and chemical properties to enhance its surface area and porosity. Our adaptation of the steam explosion technique specifically addresses the challenges of rice straw waste, marking a significant departure from previous applications. This innovation is crucial in addressing the urgent need for more sustainable waste management practices, as it effectively deconstructs the lignocellulosic matrix of rice straw. This facilitates the selective extraction of cellulose at a 70% efficiency, with a 20% yield and the subsequent recovery of lignin. The results of this study are significant for sustainable biomaterial production, offering novel insights into optimising these crucial biomass components. By refining the process and focusing on critical parameters, our work advances the application of steam explosion methods for agricultural waste, enhancing efficiency and sustainability. By utilising rice straw biowaste, this research not only proposes a solution to a pressing environmental issue but also demonstrates the potential to create new market opportunities, increase the economic value for rice producers, and significantly reduce the environmental footprint of existing waste disposal methods. The holistic and ecological approach of this study underscores the vital need for innovative strategies in agricultural waste management, positioning the valorisation of rice straw waste as a key component in the pursuit of environmental sustainability. Full article

(This article belongs to the Special Issue Research Progress in Waste Resource Utilization)

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14 pages, 1310 KiB

Open AccessArticle

Evaluation of the Thermal Energy Potential of Waste Products from Fruit Preparation and Processing Industry

by Petr Bača, Vladimír Mašán, Petr Vanýsek, Patrik Burg, Tomáš Binar, Pavel Suchý and Lenka Vaňková

Appl. Sci. 2024, 14(3), 1080; https://doi.org/10.3390/app14031080 - 26 Jan 2024

Cited by 2 | Viewed by 1481

Abstract

In the context of a changing climate and increasing efforts to use renewable energy sources and waste materials and to green the environment, new sources and technologies for energy recovery from waste are being sought. This study evaluates the possibilities of energy generation [...] Read more.

In the context of a changing climate and increasing efforts to use renewable energy sources and waste materials and to green the environment, new sources and technologies for energy recovery from waste are being sought. This study evaluates the possibilities of energy generation potential from waste products of fruit species used in the food processing industry. The results indicate good potential for energy use of materials from fruit processing due to low input moisture content of around 15 wt. %, an average energy lower heating value (LHV) of 16.5 MJ·kg⁻¹, an average low ash content of 4.9% and meeting most of the emission limits of similar biofuels. Elemental analysis and combustion residue studies indicate safe operation within existing standards. The results of our analyses and experience from similar studies allow us to recommend most of the studied waste materials for energy generation use directly in processing plants at the local level. Full article

(This article belongs to the Special Issue Research Progress in Waste Resource Utilization)

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12 pages, 3588 KiB

Open AccessArticle

Potential Application of Natural Fibres for the Reinforcement of Unpaved Forest Roads—Response after RL-CBR Tests

by David Miranda Carlos, Daniela Rodrigues, Catarina Martins, Joaquim Macedo and Margarida Pinho-Lopes

Appl. Sci. 2024, 14(3), 1006; https://doi.org/10.3390/app14031006 - 24 Jan 2024

Viewed by 1191

Abstract

Unpaved roads are essential as transportation infrastructure. These roads are traditionally built utilizing local soils and aggregates. The application of different materials to improve the strength and the overall performance of these road solutions has been investigated. This study focuses on the assessment [...] Read more.

Unpaved roads are essential as transportation infrastructure. These roads are traditionally built utilizing local soils and aggregates. The application of different materials to improve the strength and the overall performance of these road solutions has been investigated. This study focuses on the assessment of the suitability of reinforcing a fine soil using natural fibres from the forest value chain—specifically, pine needles—for unpaved forest roads. The resilient response of both unreinforced and reinforced soils was assessed with RL-CBR tests (California Bearing tests with repeated load) for different percentages of natural fibres incorporated into the soil. The force–penetration response, CBR value, recoverable and permanent displacements, and equivalent modulus were estimated. The effect of different load stages on the elastic response of both unreinforced and reinforced soils was also evaluated. The CBR values improved with the addition of pine needles; the best response was observed for specimens reinforced with 1% (mass) of these natural fibres (the CBR value increased by 45%). The equivalent modulus also was improved, showing that the stiffness of the soil increased with the inclusion of reinforcement. The findings imply that RL-CBR studies offer a promising method for obtaining important design parameters, especially for unpaved forest roads where investments in soil characterization are frequently limited. Full article

(This article belongs to the Special Issue Research Progress in Waste Resource Utilization)

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15 pages, 3874 KiB

Open AccessArticle

Gasification Performance of Barley Straw Waste Blended with Lignite for Syngas Production under Steam or Carbon Dioxide Atmosphere

by Despina Vamvuka and Konstantina Zacheila

Appl. Sci. 2024, 14(2), 665; https://doi.org/10.3390/app14020665 - 12 Jan 2024

Viewed by 1340

Abstract

The gasification performance of lignite/barley straw mixtures for syngas production was investigated. The experiments were carried out under a steam or carbon dioxide atmosphere, in fixed-bed and thermogravimetric–mass spectrometry systems. The thermal behavior, reactivity, conversion, product gas composition, liquid and gaseous by-products and [...] Read more.

The gasification performance of lignite/barley straw mixtures for syngas production was investigated. The experiments were carried out under a steam or carbon dioxide atmosphere, in fixed-bed and thermogravimetric–mass spectrometry systems. The thermal behavior, reactivity, conversion, product gas composition, liquid and gaseous by-products and interactions between fuels were determined and correlated with the structural characteristics and inherent minerals in ashes, which were analyzed via mineralogical, chemical and fusibility tests. Devolatilization of the materials up to 600 °C resulted in the carbon enrichment of chars and a 30–90-fold increase in the specific surface area. Gaseous and liquid by-products with higher heating values of 5–7 MJ/m³ and 20–28 MJ/kg could offer valuable energy. Upon steam gasification up to 1000 °C, product gas was enriched in hydrogen and carbon monoxide. The syngas yield and heating value of the gas mixture were higher for barley straw fuel (0.77 m³/kg, 11.4 MJ/m³), which, when blended with the lignite, produced upgraded products. Upon carbon dioxide gasification up to 1000 °C, barley straw char exhibited a 3-times higher rate than the lignite, as well as higher conversion (94.5% vs. 62.9%) and a higher syngas yield (0.84 m³/kg vs. 0.55 m³/kg). Lignite/barley straw blends showed synergistic effects and presented higher gasification reactivity and conversion in comparison to lignite. The overall performance of lignite was improved with the steam reagent, while that of barley straw was improved with the carbon dioxide reagent. Full article

(This article belongs to the Special Issue Research Progress in Waste Resource Utilization)

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Review

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20 pages, 2404 KiB

Open AccessReview

E-Waste Management in Serbia, Focusing on the Possibility of Applying Automated Separation Using Robots

by Dragana Nišić, Branko Lukić, Zaviša Gordić, Uroš Pantelić and Arso Vukićević

Appl. Sci. 2024, 14(13), 5685; https://doi.org/10.3390/app14135685 - 29 Jun 2024

Cited by 1 | Viewed by 2677

Abstract

To encourage proper waste management for electrical and electronic devices (e-waste), it is necessary to invest heavily in the development of recycling technologies. One way to improve the process is to automate separating the shredded parts of e-waste using a robot. This paper’s [...] Read more.

To encourage proper waste management for electrical and electronic devices (e-waste), it is necessary to invest heavily in the development of recycling technologies. One way to improve the process is to automate separating the shredded parts of e-waste using a robot. This paper’s literature review, utilizing the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) framework, showcases potential robotic technologies for e-waste separation. However, the intricate design of these devices can pose significant challenges in their implementation. Various legal, organizational, and sociological obstacles have left Serbia’s e-waste management practice underdeveloped, resulting in an unsatisfactory recycling rate. In this paper, we examined the possibility of using robots in the precise example of recycling refrigerators in a recycling center in Eastern Serbia, concluding that such a solution would have multiple positive effects, both on the employees and the working environment, on the operations of the recycling center itself, and on increasing the e-waste recycling rate in the country. Full article

(This article belongs to the Special Issue Research Progress in Waste Resource Utilization)

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