Waste Valorization Research Articles

Impacts of the COVID-19/2020 pandemic on the waste sector of Rio de Janeiro municipality, Brazil: Assessment on solid waste production in 2018 – 2023

The COVID-19/2020 crisis impacted several sectors of our society, including solid waste management (SWM). Changes in waste generation trends ─ quantity and composition ─ have been reported worldwide. Assessing waste data creates the opportunity to provide decision-makers with adequate knowledge to respond effectively to future pandemic-like situations. This work draws on data on household solid waste, healthcare waste (HCW), and recyclables collected in the Rio de Janeiro municipality, analyzed from January 2018 to December 2023. As expected, the collection of HCW in Rio de Janeiro experienced a noticeable increase in 2020 and 2021, with an average of 46.9 and 54.3 tonnes collected per month, respectively. Notably, 2021 saw a significant 42 % increase compared to 2019 (p-value < 0.001), and recyclables experienced a rise higher than 40 % in 2022 and 2023 compared with 2018–2020 (p-value < 0.05). To enhance the SWM in Rio de Janeiro, we suggest 1) Investing in thermal and thermochemical treatments for hazardous waste and non-recyclable residues, 2) Decentralized waste valorization solutions like home-composting practice and decentralized anaerobic digestion systems, and 3) Implementing oriented public awareness campaigns, enforcement of solid waste separation at the source, and creation of recycling programs considering local circumstances. This study offers a template for municipalities facing similar challenges in SWM during public health emergencies and beyond.

Life Cycle Assessment of Energy Production from Solid Waste Valorization and Wastewater Purification: A Case Study of Meat Processing Industry

The meat processing industry is a very energy-intensive and water-demanding industry that produces large amounts of solid and aqueous wastes. Therefore, methods for the effective treatment of the produced wastes have been studied in order to treat and reuse water within the industry and valorize the solid wastes for the production of energy and value-added products. The primary aim of this work is to evaluate the overall sustainability of energy produced from solid waste valorization and wastewater treatment in the meat processing industry via Life Cycle Assessment (LCA). For this purpose, the total environmental impact of a typical meat industry that utilizes conventional waste management methods (Scenario A) was evaluated and compared with two different industries with appropriate waste treatment/valorization processes. In the first studied valorization scenario (Scenario B), waste management is conducted using anaerobic digestion, composting, membrane bioreactors, and ultraviolet (UV) treatment, whereas in the second studied valorization scenario (Scenario C), aeration treatment, chlorination, and hydrothermal carbonization (HTC) are the selected treatment techniques. As expected, it is evident from this LCA study, that both Scenarios B and C exhibited a significantly improved environmental footprint in all studied indicators compared with Scenario A, with the reduction in certain environmental impact categories reaching up to 80%. Between the two studied alternative scenarios, the biggest improvement in the environmental footprint of the meat industry was observed in Scenario C, mainly due to the substantial quantity of the produced thermal energy. According to the results of the present case study, it is evident that the incorporation of appropriate methods in the meat industry can result in the efficient generation of energy and a significant improvement in the environmental footprint contributing to environmental safety and sustainability.

Bergamot Byproducts: A Sustainable Source to Counteract Inflammation.

Chronic inflammation is the result of an acute inflammatory response that fails to eliminate the pathogenic agent or heal the tissue injury. The consequence of this failure lays the foundations to the onset of several chronic ailments, including skin disorders, respiratory and neurodegenerative diseases, metabolic syndrome, and, eventually, cancer. In this context, the long-term use of synthetic anti-inflammatory drugs to treat chronic illnesses cannot be tolerated by patients owing to the severe side effects. Based on this, the need for novel agents endowed with anti-inflammatory effects prompted to search potential candidates also within the plant kingdom, being recognized as a source of molecules currently employed in several therapeutical areas. Indeed, the ever-growing evidence on the anti-inflammatory properties of dietary polyphenols traced the route towards the study of flavonoid-rich sources, such as Citrus bergamia (bergamot) and its derivatives. Interestingly, the recent paradigm of the circular economy has promoted the valorization of Citrus fruit waste and, in regard to bergamot, it brought to light new evidence corroborating the anti-inflammatory potential of bergamot byproducts, thus increasing the scientific knowledge in this field. Therefore, this review aims to gather the latest literature supporting the beneficial role of both bergamot derivatives and waste products in different models of inflammatory-based diseases, thus highlighting the great potentiality of a waste re-evaluation perspective.

Investigation of some useful chemical parameters in Shea tree (Vitelaria paradoxa) nut wastewater collected after extraction of the butter: prospects of Shea butter waste valorization

Shea butter is extracted the nut of Vitellaria paradoxa for both domestic and commercial purposes. Growing extraction and utilization of the butter especially in pharmaceutical, food and cosmetics industries result in large shea butter extraction with resultant large volumes of waste product of unknown content. Analyses of the wastewater/byproduct was carried out to review possibilities of its value addition in production of new products, or otherwise appropriate disposal. Therefore, Atomic Absorption Spectroscopy, physicochemical, and phytochemical screening methods, and extraction were used in the current study to assess antioxidant activity, BOD, calcium, iron, magnesium, lead, nickel, zinc, copper, and phytochemical content of samples of the material from Northern Ghana. The amount of residual oil was also determined. The BOD ranged from 168.00±0.00 to 86.25±6.25 mg O2/kg; Levels of magnesium in the samples ranged from 16.65 - 206.65 mg/kg, calcium from 4.72 - 19.60 mg/kg, iron was 7.75 - 14.0 mg/kg, copper from 0.02 - 0.08 mg/kg, lead from 0.33 - 1.22 mg/kg, nickel from 0.04 - 0.23 mg/kg and zinc from 3.36 - 5.80 mg/kg. Secondary metabolites present included alkaloids, phenolic, saponins, tannins and flavonoids. while residual oil extracted from the sample was between 14.67-6.46 % of the material. Mean pH was 5.95±0.05 - 6.10±0.005, and the mean temperature of the samples ranged from 24.00±0.05 to 25.25±0.05 oC at the time of analyses. From the findings the material has good and diverse content and could be used in cosmetics, pharmaceutical products or organic manure. Otherwise it should be disposed appropriately to safeguard environmental and water pollution.

Biorefinery-based sustainability assessment of macroalgae waste valorization to polylactic acid: Exergy and exergoeconomic perspectives

This study evaluated the exergetic and exergoeconomic performance of three L-lactic acid (L-LA) production scenarios. All three scenarios produced L-LA from red macroalgae waste, Eucheuma cottonii residue (ECR) with the same species of enzymes, and lactic acid bacteria (LAB). Scenario 1 is the biorefinery process for the L-LA. Scenario 2 is the biorefinery process for the L-LA with fertilizer production and wastewater treatment. Scenario 3 is the polylactic acid (PLA) biorefinery process with fertilizer production and wastewater treatment. From the study, the total production rate for L-LA was 5194 kg/hr, with a total consumption rate of 12079 kg/hr for ECR. In addition, the production rates of organic fertilizer and reused water were 1609 and 1233 kg/hr, respectively, for scenario 2. Then, the production rate of the PLA was 4142 kg/hr for scenario 3. From the comparison, the energy consumption was increased due to the increased demand for process and equipment (from 28272.53 kW to 30296.15 kW). From the exergetic analysis aspect, the highest contributor to the exergy loss was the simultaneous saccharification and fermentation (SSF) unit, totaling 18875.62 kW. For the exergoeconomic aspect, the SSF unit also contributed the highest exergy destruction cost rate (average 70%). The study results provide theoretical guidance for exergetic and economic performance improvement in future L-LA and PLA production.

Valorization of Food Waste into Single-Cell Protein: An Innovative Technological Strategy for Sustainable Protein Production.

The rapidly increasing population and climate change pose a great threat to our current food systems. Moreover, the high usage of animal-based and plant-based protein has its drawbacks, as these nutritional sources require many hectares of land and water, are affected by seasonal variations, are costly, and contribute to environmental pollution. Single-cell proteins (SCPs) are gaining a lot of research interest due to their remarkable properties, such as their high protein content that is comparable with other protein sources; low requirements for land and water; low carbon footprint; and short production period. This review explores the use of food waste as a sustainable feedstock for the advancement of SCP processes. It discusses SCP studies that exploit food waste as a substrate, alongside the biocatalysts (bacteria, fungi, yeast, and microalgae) that are used. The operational setpoint conditions governing SCP yields and SCP fermentation routes are elucidated as well. This review also demonstrates how the biorefinery concept is implemented in the literature to improve the economic potential of "waste-to-protein" innovations, as this leads to the establishment of multiproduct value chains. A short section that discusses the South African SCP scenario is also included. The technical and economic hurdles facing second-generation SCP processes are also discussed, together with future perspectives. Therefore, SCP technologies could play a crucial role in the acceleration of a "sustainable protein market", and in tackling the global hunger crisis.

Exploring business model strategies to achieve a circular bioeconomy from a waste valorization perspective

Exploring business model strategies to achieve a circular bioeconomy from a waste valorization perspective

Top-down and bottom-up microbiome engineering approaches to enable biomanufacturing from waste biomass.

This review highlights the microbial consortia-driven waste valorization for biomanufacturing through top-down and bottom-up design approaches and describes strategies, tools, and unexplored opportunities to optimize the design and stability of such consortia.

Valorization of the Red Wine Yeast Waste

Valorization of the Red Wine Yeast Waste

Hydroxylated Tetramethoxyflavone Affects Intestinal Cell Permeability and Inhibits Cytochrome P450 Enzymes.

Tetramethoxyflavones (TMFs) found in the Citrus genus have garnered considerable interest from food scientists and the health food industry because of their promising biological properties. Nonetheless, there are currently limited data available regarding the effectiveness and bioavailability of "hydroxylated TMFs", which are flavones known for their potential in disease prevention through dietary means. This study aims to provide insights into the chemical and biological properties of hydroxylated TMF and evaluates its effects on intestinal cell permeability and cytochrome P450 (CYP) inhibition. Liquid chromatography-mass spectrometry (LC-MS) and microsomes analyze the TMFs and hydroxylated TMFs, elucidating cell penetration and metabolic inhibition potential. 3H7-TMF shows the fastest (1-h) transport efficiency in intestinal cells. The Caco-2 cell model exhibits significant transport and absorption efficiency. Dissolved hydroxyl-TMF with hydrophilicity possibly permeates the gut. 3H7-TMF has higher transport efficiency (46%) 3H6-TMF (39%). IC50 values of TMFs (78-TMF, 57-TMF, 3H7-TMF, 3H6-TMF) against CYP enzymes (CYP1A2, CYP2D6, CYP2C9, CYP2C19, CYP3A4) range from 0.15 to 108 μM, indicating potent inhibition. Hydroxyl groups enhance TMF hydrophilicity and membrane permeability. TMFs display varied inhibitory effects due to hydroxyl and methoxy hindrance. This study underscores the strong CYP inhibitory capabilities in these TMFs, implying potential food-drug interactions if used in medicines or supplements. These findings can also help with food nutrition improvement and pharma food developments through innovative approaches for Citrus waste valorization.

Cultivation of recombinant Aspergillus niger strains on dairy whey as a carbohydrate source.

Agricultural waste valorisation provides a sustainable solution to waste management, and combining waste utilisation with commodity production allows for responsible production processes. Recombinant Aspergillus niger D15 strains expressing fungal endoglucanases (Trichoderma reesei eg1 and eg2 and Aspergillus carneus aceg) were evaluated for their ability to utilise lactose as a carbon source to determine whether dairy waste could be used as a feedstock for enzyme production. The recombinant A. niger D15[eg1]PyrG, D15[eg2]PyrG, and D15[aceg]PyrG strains produced maximum endoglucanase activities of 34, 54, and 34 U/mL, respectively, on lactose and 23, 27, and 22 U/mL, respectively, on whey. The A. niger D15[eg2]PyrG strain was used to optimise the whey medium. Maximum endoglucanase activity of 46 U/mL was produced on 10% whey medium containing 0.6% NaNO3. The results obtained indicate that dairy whey can be utilised as a feedstock for recombinant enzyme production. However, variations in enzyme activities were observed and require further investigation.

Energy Recovery from Municipal Solid Waste through Co-Gasification Using Steam or Carbon Dioxide with Olive By-Products

The valorization of untreated municipal waste (MSW) biochar for energetic uses, through its co-gasification with olive stone (OST) biochar under a steam or carbon dioxide atmosphere, was investigated. The experiments were conducted in a fixed bed unit and a thermal analysis–mass spectrometer system. The thermal behavior, reactivity, conversion, product gas composition, syngas yield and energy potential were determined, while the influence of the fuel’s internal structure, chemical functional groups and operating conditions were examined. The concentrations of H2 and CO2 in the product gas mixture under a steam atmosphere were increased with steam/biochar ratio, while that of CO was reduced. At a steam/biochar = 3 H2 yield, the higher heating value and conversion for the OST were 52.8%, 10.8 MJ/m3 and 87.5%; for the MSW, they were 44.4%, 9.9 MJ/m3 and 51.5%, whereas for their blend, they were 50%, 10.6 MJ/m3 and 76.6%, respectively. Under a carbon dioxide atmosphere, the reactivity and conversion of the OST biochar (84%) were significantly higher as compared with the MSW biochar (50%). The higher heating value of the product gas was 12.4–12.9 MJ/m3. Co-gasification of the MSW with OST (in proportions 30:70) resulted in the enhanced reactivity, conversion, syngas yield and heating value of product gas compared with gasification of solely MSW material.

Pioneering the Future: A Trailblazing Review of the Fusion of Computational Fluid Dynamics and Machine Learning Revolutionizing Plasma Catalysis and Non-Thermal Plasma Reactor Design

The advancement of plasma technology is intricately linked with the utilization of computational fluid dynamics (CFD) models, which play a pivotal role in the design and optimization of industrial-scale plasma reactors. This comprehensive compilation encapsulates the evolving landscape of plasma reactor design, encompassing fluid dynamics, chemical kinetics, heat transfer, and radiation energy. By employing diverse tools such as FLUENT, Python, MATLAB, and Abaqus, CFD techniques unravel the complexities of turbulence, multiphase flow, and species transport. The spectrum of plasma behavior equations, including ion and electron densities, electric fields, and recombination reactions, is presented in a holistic manner. The modeling of non-thermal plasma reactors, underpinned by precise mathematical formulations and computational strategies, is further empowered by the integration of machine learning algorithms for predictive modeling and optimization. From biomass gasification to intricate chemical reactions, this work underscores the versatile potential of plasma hybrid modeling in reshaping various industrial processes. Within the sphere of plasma catalysis, modeling and simulation methodologies have paved the way for transformative progress. Encompassing reactor configurations, kinetic pathways, hydrogen production, waste valorization, and beyond, this compilation offers a panoramic view of the multifaceted dimensions of plasma catalysis. Microkinetic modeling and catalyst design emerge as focal points for optimizing CO2 conversion, while the intricate interplay between plasma and catalysts illuminates insights into ammonia synthesis, methane reforming, and hydrocarbon conversion. Leveraging neural networks and advanced modeling techniques enables predictive prowess in the optimization of plasma-catalytic processes. The integration of plasma and catalysts for diverse applications, from waste valorization to syngas production and direct CO2/CH4 conversion, exemplifies the wide-reaching potential of plasma catalysis in sustainable practices. Ultimately, this anthology underscores the transformative influence of modeling and simulation in shaping the forefront of plasma-catalytic processes, fostering innovation and sustainable applications.

Co-pyrolysis of biomass and polyethylene terephthalate (PET) as an alternative for energy production from waste valorization

Disposal of waste plastics is an environmental problem that has gained attention over the years. Co-pyrolysis is a promising alternative for transforming this material into solid and liquid products with high added value. This study evaluated how heating rates and polyethylene terephthalate (PET) proportions influence the properties of char obtained by co-pyrolysis. The co-pyrolysis process was carried out using Eucalyptus spp biomass, in three proportions of PET (0, 15 and 25 %) and three heating rates (1, 3 and 5 °C min−1), at a final temperature of 450 °C. We investigated the physical, chemical, energetic and thermal properties of the char produced, which included its morphology via scanning electron microscopy (SEM). The average yield of co-pyrolytic char, under all conditions of co-pyrolysis, decreased by 5 % compared to the biomass-only pyrolytic material. In addition to yield differences, the percentage of ash decreased by about 7 % in char with PET. The produced material had a maximum heating value of 32,17 MJ kg−1 and maximum energy density of 4.7 Gcal m−3 (1.10 GJ m−3). These results show the synergistic effect between PET and biomass, pointing to improvements in char generated through co-pyrolysis. The addition of PET in the process, in all conditions investigated, contributed to potentiating the energy characteristics of the material. This co-pyrolysis process can be an alternative for generation and biofuels. The co-pyrolysis of biomass and polyethylene terephthalate is a promising strategy for generating energy products and ensuring the reuse of plastic materials.

Environmentally friendly concrete block production: valorization of civil construction and chemical industry waste.

In the present work, a study was carried out on the dosage of wastes from the chemical industry (tannery sludge) and civil construction (concrete and plaster) in mixtures used in concrete blocks' production. The objective was the application of these blocks in paving. The characterization of the materials used was performed employing X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The effect of the different residues on the blocks' properties was evaluated through compressive strength, flexion-traction, water absorption, abrasion resistance, and leaching tests. The results indicated that the concrete paving blocks produced with the addition of residues did not obtain gains in the values of mechanical resistance to compression and traction in bending compared to blocks made with standard raw material. However, the blocks produced with construction waste presented satisfactory results for application in street paving after 7days of concrete curing, reaching values between 36.54 and 44.6MPa for the mentioned properties. These values also increased to 21.4% within 28days of curing. The blocks produced with plaster showed values between 37.03 and 39.85MPa after 28days of curing, allowing their use for street paving. On the other hand, the blocks containing residues from the chemical industry had lower strengths, reaching a maximum of 29.36MPa after 28days of curing. In addition, it was also noted that the blocks produced with recycled concrete showed an improvement in performance for a composition of 50% recycled material.

Black soldier fly larvae should be considered beyond their use as feedstuff

Abstract In recent years the entomological landscape has witnessed substantial progress in the promotion of insects for food and feed purposes. In particular, the black soldier fly (BSF) sector is experiencing an unprecedented expansion and is attracting growing attention from both researchers and entrepreneurs. Despite the well-established supply chain based on the valorisation of waste and by-products by BSF larvae for producing feedstuff, the BSF industry is considering alternative challenging substrates for rearing the larvae and exploring novel applications of bioactive molecules from BSF beyond animal feed. This editorial challenges the conventional boundaries of the insects for food and feed sector, and delves into the innovative use of BSF proteins, lipids, and chitin, pointing out diverse opportunities across the biomedical, biotechnological, agricultural, zootechnical, and environmental sectors that could further propel the utilisation of this insect.

Bioprospecting CAZymes repertoire of Aspergillus fumigatus for eco-friendly value-added transformations of agro-forest biomass

BackgroundValorizing waste residues is crucial to reaching sustainable development goals and shifting from a linear fossil-based economy to a circular economy. Fungal cell factories, due to their versatility and robustness, are instrumental in driving the bio-transformation of waste residues. The present work isolated a potent strain, i.e., Aspergillus fumigatus (ZS_AF), from an ancient Złoty Stok gold mine, which showcased distinctive capabilities for efficient hydrolytic enzyme production from lignocellulosic wastes.ResultsThe present study optimized hydrolytic enzyme production (cellulases, xylanases, and β-glucosidases) from pine sawdust (PSD) via solid-state fermentation using Aspergillus fumigatus (ZS_AF). The optimization, using response surface methodology (RSM), produced a twofold increase with maximal yields of 119.41 IU/gds for CMCase, 1232.23 IU/gds for xylanase, 63.19 IU/gds for β-glucosidase, and 31.08 IU/gds for FPase. The secretome profiling validated the pivotal role of carbohydrate-active enzymes (CAZymes) and auxiliary enzymes in biomass valorization. A total of 77% of carbohydrate-active enzymes (CAZymes) were constituted by glycoside hydrolases (66%), carbohydrate esterases (9%), auxiliary activities (3%), and polysaccharide lyases (3%). The saccharification of pretreated wheat straw and PSD generated high reducing sugar yields of 675.36 mg/g and 410.15 mg/g, respectively.ConclusionThese findings highlight the significance of an efficient, synergistic, and cost-effective arsenal of fungal enzymes for lignocellulosic waste valorization and their potential to contribute to waste-to-wealth creation through solid-waste management. The utilization of Aspergillus fumigatus (ZS_AF) from an unconventional origin and optimization strategies embodies an innovative approach that holds the potential to propel current waste valorization methods forward, directing the paradigm toward improved efficiency and sustainability.

Accelerated carbonation of waste paper fly ash by liquid process (NaHCO3) for stabilization of Ba and Pb

The increase of energy valorization of paper sludge waste and biomass due to their high calorific value by incineration leads to an increase of waste paper fly ash (WPFA) quantities, which are in most cases considered as hazardous, and must be dealt with accordingly. The Alternative options for the management of WPFA, such as stabilization/solidification, vitrification or sintering, are not fully developed or either costly. In the present study, accelerated carbonation technology was used to reduce the hazardous nature of WPFA by improving the stabilization of metallic and metalloids trace elements (MMTE), especially Barium (Ba) and Lead (Pb) leaching. The accelerated carbonation of WPFA was found to be optimal at a water/solid ratio of 0.3 L/kg under controlled temperature and humidity conditions. The use of water saturated with 25% sodium bicarbonate (NaHCO3) improved the carbonation of WPFA and the stabilization of Ba and Pb. Batch leaching tests based on thermodynamic equilibrium was used to evaluate the solubility of the MMTE as a function of pH and at the natural pH of non‑carbonated and carbonated WPFA. Thermogravimetry, X-ray diffraction, scanning electron microscopes and energy dispersive spectroscopy analyses were performed to investigate the evolution of carbonation over time and its effect on the chemical and mineralogical properties of WPFA. After 30 days of accelerated carbonation, the leaching concentration of Ba and Pb was below the French legal limit. The leaching concentration of Ba and Pb from carbonated samples decreased 99% and 99.5% respectively. The leaching and release potential behavior of carbonated WPFA were further evaluated using the four-step sequential extraction procedure proposed by the Commission of the European Communities Bureau of Reference (BCR). The speciation of MMTE underwent significant transformation, shifting predominantly from the soluble fraction to the carbonated fraction as a result of the carbonation reaction.

Photovoltaic-driven Ni(ii)/Ni(iii) redox mediator for the valorization of PET plastic waste with hydrogen production.

Electrocatalytic valorization of PET plastic waste provides an appealing route by converting intermittent renewable energy into valuable chemicals and high-energy fuels. Normally, anodic PET hydrolysate oxidation and cathodic water reduction reactions occur simultaneously in the same time and space, which increases the challenges for product separation and operational conditions. Although these problems can be addressed by utilizing membranes or diaphragms, the parasitic cell resistance and high overall cost severely restrict their future application. Herein, we introduce a Ni(ii)/Ni(iii) redox mediator to decouple these reactions into two independent processes: an electrochemical process for water reduction to produce hydrogen fuel assisted by the oxidation of the Ni(OH)2 electrode into the NiOOH counterpart, followed subsequently by a spontaneous chemical process for the valorization of PET hydrolysate to produce formic acid with a high faradaic efficiency of ∼96% by the oxidized NiOOH electrode. This decoupling strategy enables the electrochemical valorization of PET plastic waste in a membrane-free system to produce high-value formic acid and high-purity hydrogen production. This study provides an appealing route to facilitate the transformation process of PET plastic waste into high-value products with high efficiency, low cost and high purity.

A Review and Current Practices on the Valorization of Ship-Generated Oily Waste

The valorization of ship-generated oily waste involves the processing and recovery of hydrocarbons and other materials present in these wastes, which is crucial for reducing marine pollution and risks to coastal ecosystems. However, the literature on this subject is currently scarce and underdeveloped. Our aim is to explain and classify the different types of ship wastes, to detail how hydrocarbon residues are produced on ships, and to examine various methods of treating and valorizing these wastes. This approach will facilitate our future research efforts to digitize a carefully selected technology for valorizing ship-generated oily waste.