Waste Valorization Research Articles

A lab experiment on metals separation and recovery from waste ink-jet cartridges as a non-formal appealing learning activity for students of secondary schools

Abstract Since 2004, the Italian Ministry of Education, University and Research (MIUR), the Conference of Science and Technology Headmasters, and Confindustria, have been promoting the National Plan for Scientific Degrees (PLS) aimed at supporting students in acquiring scientific skills better responding to contemporary society challenges and increasing vocations in basic sciences. This paper describes a successful experience of the University of Cagliari together with selected local secondary schools, in which the hot topic of technological waste valorization was selected to create an orientation laboratory for students towards chemistry disciplines. Specifically, students and teachers were guided into the challenging world of e-waste production and treatment through the practical activity of noble metals recovery from real waste ink-jet cartridges. A specific emphasis was placed on fundamental chemical aspects – separation and recovery of metals driven by redox processes favored by a complexing agent – as well as on the chance to play on coordination chemistry to promote a green chemistry approach. The close collaboration between school and university teachers in planning and implementing laboratory activities is the element that characterizes PLS actions and promotes the development and strengthening of relations between secondary school and university courses in science, technology, engineering, and mathematics (STEM).

Valorization of agroindustrial orange peel waste during the optimization of activated carbon–multiwalled carbon nanotubes–zinc oxide composites used in the removal of methylene blue in wastewater

Activated carbons (AC) produced from agroindustrial orange peel (OP) wastes and/or commercial multi–walled carbon nanotubes (MWCNTs) were modified with ZnO nanoparticles in different amounts (15 and 30 wt–%) for the removal of methylene blue in aqueous solutions. The MWCNTs functionalization was carried out by typical procedure in acid medium using a ratio of 3:1 (HNO3/H2SO4). A batch adsorption analysis was carried out evaluating different parameters: MB concentration from 40 to 100 mg L–1; pH values between 4 and 10 and adsorption time that varied from 1 to 48 h. The modified materials were characterized through the techniques XRD, FTIR, BET, TGA, SEM and UV–vis. The results showed an adequate dispersion of ZnO NPs on the carbon surfaces with a typical flower–like morphology this type of shape developed micropores that facilitate adsorption phenomena. Under the evaluation conditions, 20 mg of carbon–based materials can remove up to 89.5 ± 4.47 % of MB (80 ppm) after 24 h of exposure at a regulated pH of 8. The equilibrium adsorption data were better fitted by a Langmuir isotherm (R2 = 0.9999) than the Freundlich model (R2 = 0.9366); showing in the best case a maximum adsorption capacity of 1250 mg g−1 for both materials with 30 wt–% of ZnO NPs (AC–MWCTs or MWCNTs). Experimental data also suggest that the most likely mechanism is chemisorption followed by physical adsorption. Then, the compounds with 30 wt–% metal loading (ZnO NPs), AC–MWCNTs–ZnO or MWCNTs–ZnO, displayed the most interesting properties for MB dye removal. AC–ZnO compounds can also remove about 88.75 ± 4.43 % of MB, demonstrating that it can also be a facile and low–cost method to improve the surface area in carbonaceous structures by promoting a strong interaction with the ZnO NPs, which in turn helps to remove contaminants in water efficiently.

Valorization of bean agricultural wastes for the production of polymeric composites

Valorization of bean agricultural wastes for the production of polymeric composites

Valorization of bean agricultural wastes for the production of polymeric composites

Valorization of bean agricultural wastes for the production of polymeric composites

The role of digital platforms in e-commerce food supply chain resilience under exogenous disruptions

PurposeOperational risks can cause considerable, atypical disturbances and impact food supply chain (SC) resilience. Indicatively, the COVID-19 pandemic caused significant disruptions in the UK food services as nationwide stockouts led to unprecedented discrepancies between retail and home-delivery supply capacity and demand. To this effect, this study aims to examine the emergence of digital platforms as an innovative instrument for food SC resilience in severe market disruptions.Design/methodology/approachAn interpretive multiple case-study approach was used to unravel how different generations of e-commerce food service providers, i.e. established and emergent, responded to the need for more resilient operations during the COVID-19 pandemic.FindingsSC disruption management for high-impact low-frequency events requires analysing four research elements: platformisation, structural variety, process flexibility and system resource efficiency. Established e-commerce food operators use partner onboarding and local waste valorisation to enhance resilience. Instead, emergent e-commerce food providers leverage localised rapid upscaling and product personalisation.Practical implicationsDigital food platforms offer a highly customisable, multisided digital marketplace wherein platform members may aggregate product offerings and customers, thus sharing value throughout the network. Platform-induced disintermediation allows bidirectional flows of data and information among SC partners, ensuring compliance and safety in the food retail sector.Originality/valueThe study contributes to the SC configuration and resilience literature by investigating the interrelationship among platformisation, structural variety, process flexibility and system resource efficiency for safe and resilient food provision within exogenously disrupted environments.

Unlocking value: circular economy in ngos' food waste reduction efforts in Brazil and Togo

This article delves into the intriguing realm of food waste valorization conducted by nongovernmental organizations (NGOs) in two distinct locales—Brasilia, Brazil, and Lomé, Togo. The primary focus of this exploration is the lens of the Circular Economy (CE), a concept that emphasizes the sustainable utilization of resources within closed loops. The discourse is further enriched by introducing the notion of upcycling, a complementary force to the Circular Economy, particularly within the intricate web of food supply chains. The ReSOLVE framework, a strategic approach for managing food waste, is a guiding light in this research. Upon dissecting the outcomes, noteworthy limitations come to the forefront, shedding light on the challenges of aligning NGOs from both countries with the principles of the Circular Economy in their food waste management endeavors. These challenges assume heightened significance against the backdrop of the intricate global food security landscape, effectively underlining the intricacies of harmonizing the Circular Economy's ambitions with the pragmatic goal of diminishing food waste. The overarching objective of this study is to galvanize circular-oriented initiatives that can effectively curtail and prevent food wastage on a global scale, with a particular emphasis on developing nations. This pursuit is underscored by the triad of benefits such initiatives confer: economic advancement, social amelioration, and a positive ecological footprint. In an era where sustainability stands as a paramount concern, this research advocates for concerted efforts to harmonize the noble ideals of the Circular Economy with the pressing need for food waste reduction, especially within regions striving for holistic growth and development.

Innovative Cutting and Valorization of Waste Fishing Trawl and Waste Fishing Rope Fibers in Cementitious Materials

The valorization of waste fishing trawl (WFT) and waste fishing rope (WFR) fibers in cementitious materials (CMs) has gained attention in recent years; however, the lack of information on the cutting and cleaning techniques for these fibers hinders their widespread commercial utilization. Existing research primarily relies on manual cutting, which proves to be impractical for large-scale production due to its time-consuming nature and lack of industrial feasibility. This research is a component of the VALNET project and introduces an innovative technique that utilizes the cutting mill to convert WFT and WFR into fibers to effectively overcome the constraints of earlier methodologies. By employing a rotor with blades, this apparatus enables efficient and precise cutting of WFT and WFR, eliminating the need for labor-intensive manual cutting. The sustainable cleaning of WFT and WFR was carried out utilizing rain and wind by placing them outside for a certain period of time. The advancements presented in this study provide a pathway for an efficient and scalable valorization of WFT and WFR fibers in CM. The study focused on analyzing the impact of varying fiber sizes and percentages on the mechanical properties of CM. Different sizes obtained from the cutting machine and different fiber percentages were examined to gain a better understanding of their influence. The fibers obtained by the utilization of a 20 mm sieve yield optimal outcomes, while the incorporation of fibers at a volume fraction of 0.5% yields the most favorable results. Furthermore, the study presents evidence of a noticeable rise in porosity resulting from the incorporation of WFT and WFR fibers, regardless of their size and proportion. Porosity slightly increases as the fiber length increases, but the rise in fiber proportion leads to a significantly greater increase in porosity.

Reuse of Residual Brewer’s Yeast: Valorization of Industrial Waste as a Source of Nutrients for Dairy Cattle

Reuse of Residual Brewer’s Yeast: Valorization of Industrial Waste as a Source of Nutrients for Dairy Cattle

Microwave-assisted pyrolysis in biomass and waste valorisation: Insights into the life-cycle assessment (LCA) and techno-economic analysis (TEA)

Microwave-assisted pyrolysis (MAP) has been perceived as a promising technology for biomass and waste conversion due to its distinctive features, including fast, even, and precise heating. This results in higher energy efficiency when compared to conventional pyrolysis via thermal heating. However, the scaling up of MAP of biomass and waste poses challenges, with investigations ongoing to uncover not only the technological aspect, but also both the environmental impacts and economic feasibility associated with this process/technology. The possible environmental impacts associated with MAP processes can be analyzed through systematic life-cycle assessment (LCA), while the economic feasibility can be evaluated via techno-economic analysis (TEA). This paper presents an overview of the current research trend in MAP and the products produced, as well as the LCA and TEA of the pyrolysis technologies. The LCA study reported a 2.5 folds reduction in energy consumption and up to 62% reduction in global warming potential. TEA study revealed that conventional pyrolysis has a greater profit for long-term assessment due to a higher maturity and less complexity technology; however, MAP may be more economically feasible in the future owing to the increased maturity and more established technology. Finally, the challenges and future perspectives for LCA and TEA in MAP are elucidated.

Expanded polystyrene waste valorization as a hydrophobic coating II: packaging application

The application of the expanded polystyrene (EPS) waste to the functional material is still a challenge. The hydrophobic property of polystyrene has a potential to create a superhydrophobic surface. Here, we use expanded polystyrene waste to coat surfaces in two different ways—spray coating and dip coating—to produce superhydrophobic surfaces for food packaging. The ZnO was employed to make the surface rougher. However, the combination of ZnO and EPS waste produces only a hydrophobic surface. For spray coating and dip coating, the maximum water contact angle is 119° and 125° respectively. The scanning electron microscope (SEM) picture reveals many holes that increase the surface's roughness. The hydrophobic surface significantly cuts down on cleaning time. According to the food packaging parameter test mandated by the Indonesian Food and Drug Administration (BPOM) (BPOM regulation No. 20, 2019), the coating complies with heavy metals and ethanol stimulant migration testing requirements for food packaging. However, the migration condition in acetic acid stimulant surpasses the maximum standard. The total migration in 3% acetic acid stimulant (40°C for 10 days) is 22.95 mg/dm2 while the maximum value is 10 mg/dm2.

Hydrodeoxygenation of Oxygen-Containing Aromatic Plastic Wastes into Cycloalkanes and Aromatics.

Chemical recycling and upcycling offer promising approaches for the management of plastic wastes. Hydrodeoxygenation (HDO) is one of the appealing ways for conversion of oxygen-containing plastic wastes, including polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), polyphenyl ether (PPO), and polyether ether ketone (PEEK), into cyclic alkanes and aromatics in high yields under mild reaction conditions. The challenge lies in achieving C-O activation while preserving C-C bonds. In this review, we highlight the recent advancements in catalytic strategies and catalysts for the conversion of these oxygen-containing plastic wastes into cycloalkanes and aromatics. The reaction systems, including multi-step routes, direct HDO and transfer HDO methods, are exemplified. The design and performance of HDO catalysts are systematically summarized and compared. We comprehensively discuss the functions of the catalysts' components, reaction pathway and mechanism to gain insights into the HDO process for efficient valorization of oxygen-containing plastic wastes. Finally, we provide perspectives for this field, with specific emphasis on the non-noble metal catalyst design, selectivity control, reaction network and mechanism studies, mixed plastic wastes management and product functionalization. We anticipate that this review will inspire innovations on the catalytic process development and rational catalyst design for the HDO of oxygen-containing aromatic plastics to establish a low-emission circular economy.

Valorization of the Residual Fraction of Coal Tailings: A Mineral Circularity Strategy for the Clay Ceramic Industry in the Carboniferous Region of Santa Catarina, Southern Brazil.

Mineral extraction of coal in the carboniferous region of southern Santa Catarina (Brazil) plays a significant role in the regional economy. However, this activity has severe environmental impacts, with approximately 65% of the extracted mineral being discarded as a rejected material (deposited in landfills). The identification of the technological potential of these materials, based on the geological aspects of the extraction site and the beneficiation operations applied to obtain coal, provides the opportunity to add value to different residual fractions that can be reused. Thus, waste valorization, the main objective of this work, has recently become a strategy for the application of these minerals in the production of clay ceramics using a systematic approach named CPQvA, which means "classification, potentiality, quantity/viability, and applicability". The use of these materials as secondary mineral sources can avoid the deposition of these materials in industrial landfills and help to reduce the pressure on landfills, which receive an average of four million tons of material annually. In this study, the residual fraction, part of the tailing from coal beneficiation, known as coal fines, was evaluated for formulation valorization in clay ceramics. This residual fraction was classified as non-hazardous (class II-A, non-inert). X-ray fluorescence spectrometry, X-ray diffraction, and thermogravimetric analysis were performed to characterize the moisture content, particle-size distribution, and coal content to be used in the development of different formulations using the residual fraction of coal tailings (ranging from 0 to 40%) that are of technological interest to the sector. Processing parameters, such as firing at different temperatures (750, 800, 850, and 900 °C), were also correlated with these formulations. The results were compared with those of a reference ceramic formulation from the local productive arrangement of Morro da Fumaça (Arranjo Produtivo Local Cerâmica Vermelha de Morro da Fumaça). The various relationships between the materials were characterized in terms of their thermal shrinkage, water absorption, and mechanical resistance. Leaching and solubilization environmental tests revealed that both the industrial standard formulation and formulations with the application of the residual fraction were classified as non-hazardous materials. Thus, the method of using a mining residual fraction in the formulation of clay ceramics proved to be beneficial for the circular economy in the regional mineral sector through productive and environmental gains; the primary mineral resource and energy consumptions and the impacts related to waste generation were reduced. The results of this study can be applied to similar situations in other parts of the world.

Facilitating the Critical Mineral Future: Valorization of Kaolin Mining Waste through Partnerships

Facilitating the Critical Mineral Future: Valorization of Kaolin Mining Waste through Partnerships

Optimizing carrot pulp waste valorization via thermochemical conversion using carbon dioxide

This study proposes an environmentally sustainable approach for converting food waste into fuels and chemicals, especially focusing on syngas production. The carbon-negative aspect of the pyrolysis process was achieved by employing CO2 as the reaction medium. Carrot pulp waste (CPW) was used as an exemplary food waste in this work. In the single-stage pyrolysis of CPW, the presence of CO2 led to improved syngas generation. The introduction of CO2, rather than N2 carrier gas, resulted in substantial increase of CO formation at temperatures ≥ 400 °C, with a decrease in bio-oil production. This phenomenon was due to the chemical reactions between CO2 and the volatile organic compounds (VOCs) produced during the pyrolysis of CPW. Specifically, CO2 played a mechanistic role by providing an extra oxygen source for CO production and participating in the oxidative thermal cracking of VOCs. In-depth analysis of multi-stage pyrolysis verified the mechanistic role of CO2, particularly at temperatures ≥ 190 °C. However, CO2-induced reactions influenced the molecular size of the VOCs. To boost the CO2-induced reactions for additional syngas formation, a nickel-based catalyst was introduced during the pyrolysis of CPW, which effectively expedited the homogeneous reactions initiated by CO2, thereby indicating its potential to accelerate and optimize food waste valorization.

Valorisation of Agri-Food Waste for Bioactive Compounds: Recent Trends and Future Sustainable Challenges.

Worldwide, a massive amount of agriculture and food waste is a major threat to the environment, the economy and public health. However, these wastes are important sources of phytochemicals (bioactive), such as polyphenols, carotenoids, carnitine, coenzymes, essential oils and tocopherols, which have antioxidant, antimicrobial and anticarcinogenic properties. Hence, it represents a promising opportunity for the food, agriculture, cosmetics, textiles, energy and pharmaceutical industries to develop cost effective strategies. The value of agri-food wastes has been extracted from various valuable bioactive compounds such as polyphenols, dietary fibre, proteins, lipids, vitamins, carotenoids, organic acids, essential oils and minerals, some of which are found in greater quantities in the discarded parts than in the parts accepted by the market used for different industrial sectors. The value of agri-food wastes and by-products could assure food security, maintain sustainability, efficiently reduce environmental pollution and provide an opportunity to earn additional income for industries. Furthermore, sustainable extraction methodologies like ultrasound-assisted extraction, pressurized liquid extraction, supercritical fluid extraction, microwave-assisted extraction, pulse electric field-assisted extraction, ultrasound microwave-assisted extraction and high hydrostatic pressure extraction are extensively used for the isolation, purification and recovery of various bioactive compounds from agri-food waste, according to a circular economy and sustainable approach. This review also includes some of the critical and sustainable challenges in the valorisation of agri-food wastes and explores innovative eco-friendly methods for extracting bioactive compounds from agri-food wastes, particularly for food applications. The highlights of this review are providing information on the valorisation techniques used for the extraction and recovery of different bioactive compounds from agricultural food wastes, innovative and promising approaches. Additionally, the potential use of these products presents an affordable alternative towards a circular economy and, consequently, sustainability. In this context, the encapsulation process considers the integral and sustainable use of agricultural food waste for bioactive compounds that enhance the properties and quality of functional food.

Agricultural Wastes and Their By-Products for the Energy Market

The conversion of lignocellulosic agricultural waste into biofuels and other economically valuable compounds can reduce dependence on fossil fuels, reduce harmful gas emissions, support the sustainability of natural resources, including water, and minimize the amount of waste in landfills, thus reducing environmental degradation. In this paper, the conversion of agricultural wastes into biomethane, biohydrogen, biodiesel, bioethanol, biobutanol, and bio-oil is reviewed, with special emphasis on primary and secondary agricultural residues as substrates. Some novel approaches are mentioned that offer opportunities to increase the efficiency of waste valorization, e.g., hybrid systems. In addition to physical, chemical, and biological pretreatment of waste, some combined methods to mitigate the negative effects of various recalcitrant compounds on waste processing (alkali-assisted thermal pretreatment, thermal hydrolysis pretreatment, and alkali pretreatment combined with bioaugmentation) are evaluated. In addition, the production of volatile fatty acids, polyhydroxyalkanoates, biochar, hydrochar, cellulosic nanomaterials, and selected platform chemicals from lignocellulosic waste is described. Finally, the potential uses of biofuels and other recovered products are discussed.

Valorisation of bread wastes via the bacterial cellulose production

AbstractThe short shelf life of bread can be attributed to changes in its textural and sensory properties, a process termed staling, and large amounts of bread residue and waste are generated daily. Because the main component of bread is starch, the use of bread wastes as a substrate for bacterial cellulose (BC) production can significantly contribute to valorisation and reuse of wastes. This study aimed to investigate the BC production potential of various stale breads, convert these wastes into usable forms for food and other industries, and increase their economic value. Stale breads were hydrolyzed with dilute acid, and BC-producing bacteria from Kombucha tea were isolated and identified as Gluconobacter oxydans MG2021 (GO). BCs were produced from bread hydrolysates with GO and Komagataeibacter hansenii GA2016 (KH), and their properties were examined. The results indicated that stale breads represented a good source for BC production, as high BC yields were obtained using GO (8.81%–25.02%) and all BCs had superior properties such as high crystallinity (75.96%–91.39%), thermal stability, liquid holding capacity, and fine fibers (40.16–85.39 nm). This study demonstrated that bread wastes could be used as a low-cost substrate for large-scale BC production, and the abundance of bread wastes demonstrated their potential as a resource for commercial BC producers.

Agricultural Waste Valorization: Exploring Environmentally Friendly Approaches to Bioenergy Conversion

The pursuit of sustainable energy production through the conversion of agricultural waste into different bioenergy resources is of paramount importance given its potential to mitigate environmental impact while meeting energy demands. In this review, a comprehensive overview of the technologies for the biochemical and thermochemical conversion of agricultural waste into bioenergy is provided. A summary of the process of its conversion into different bioenergy products such as biogas, bio-oil, and biofuel is provided, in addition to the potential advantages and challenges faced using different biomass conversion technologies. The review highlights the potential of agricultural waste valorization to address the current energy demand while at the same time contributing to environmental benefits and greenhouse gas emission reductions. Moreover, this review highlights some significant gaps for improvement. These include the challenges in the pretreatment of agricultural waste biomass in optimizing the conversion rates and lowering the required energy consumption throughout the process while enhancing both the quantity and quality of the output. Some recommendations are proposed to address the identified challenges. These include the need for further studies for a thorough assessment to evaluate the efficacity and sustainability of agricultural waste valorization technologies. Assessment methods such as life cycle assessment (LCA), life cycle analysis (LCA), net energy ratio (NER) calculations, life cycle costing (LCC), as well as techno-economic assessment (TEA), are recommended, together with collaboration among governments, farmers, and researchers, as well as the integration of cutting-edge technologies to enhance various aspects of agricultural waste, optimizing the conversion process, cost efficiency, time management, and labor requirements, consequently boosting the conversion efficiency and product quality.

Circular bioeconomy practices and their associations with household food security in four RUNRES African city regions

Achieving the United Nation’s 2030 agenda which aims, among other goals, to ensure sustainable consumption and production patterns, requires a sustainable resource use model deployed at scale across global food systems. A circular bioeconomy (CBE) model of resource use has been proposed to reuse of organic waste in agricultural production to enhance food security. However, despite several initiatives recently introduced towards establishing a CBE in sub-Saharan Africa (SSA), minimal scientific efforts have been dedicated to understanding the association of CBE practices and food security. This study use data from 777 smallholder farm households from DRC, Ethiopia, Rwanda, and South Africa, to examine associations between three CBE practices (use of organic waste as compost, as livestock feed, and sorting waste) and household food security. Using different regression and propensity score matching models (PSM). Result reveal that using CBE practices more likely adds a 0.203 score of food insecurity access prevalence (HFIAP), 1.283 food insecurity access scale (HFIAS-score) and 0.277 for household dietary diversity score (HDDS) among households using CBE practiced groups. Associations regarding using organic waste as compost are generally positive but insignificant, while those with sorting waste are significantly and consistently negative. Thus, CBE innovations aiming to enhance household food security could prioritize organic waste valorization into livestock feed consider socio economic aspects such as access to land, access to market, education level, using mobile phone, income and city regions where interventions took place. However, prior sorting of waste is necessary to enable effective waste valorization.

Integration of lactic acid biorefinery with treatment of red mud from alumina refinery: win–win paradigm for waste valorization

The cost of detoxification and neutralization poses certain challenges to the development of an economically viable lactic acid biorefinery with lignocellulosic biomass as feedstock. Herein, red mud, an alkaline waste, was explored as both a detoxifying agent and a neutralizer. Red mud treatment of lignocellulosic hydrolysate effectively removed the inhibitors generated in dilute acid pretreatment, improving the lactic acid productivity from 1.0 g/L·h−1 to 1.9 g/L·h−1 in later fermentation. In addition, red mud could replace CaCO3 as a neutralizer in lactic acid fermentation, which in turn enabled simultaneous bioleaching of valuable metals (Sc, Y, Nd, and Al) from red mud. The neutralization of alkali in red mud by acids retained in lignocellulosic hydrolysate and lactic acid produced from fermentation led to effective dealkalization, rendering a maximum alkali removal efficiency of 92.2 %. Overall, this study offered a win–win strategy for the valorization of both lignocellulosic biomass and red mud.