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- Recycling, Vol. 9, Pages 52: Sustainability in the Generation of Household
Waste from Dishwasher Sponges for the Purpose of a New Adsorbent Material
and Its Operating Costs
Authors: Daniel Mantovani, Luís Fernando Cusioli, Diana Aline Gomes, Rosângela Bergamasco, Angelo Marcelo Tusset, Giane Gonçalves Lenzi
First page: 52
Abstract: The major problems related to environmental pollution are increasingly present among us. The uncontrolled use and incorrect disposal of products means that these problems are increasing at frightening rates. In this context, a major related problem is the incorrect disposal of dishwasher sponges that are no longer useful; their material being made up of petroleum derivatives causes this problem to be leveraged in the environment. In the present work, we evaluated and carried out tests in which these dirty sponges that would be discarded were used for the purpose of developing new sustainable adsorbent materials. These materials were washed and dried, crushed and made available for use, by which they were kept in contact with a paracetamol solution, evaluating the effect of mass, pH, kinetics, equilibrium, thermodynamic parameters, and cost analyses. The results demonstrated an adsorptive capacity of approximately 40 mg g−1 and its cost was relatively viable, since this material would otherwise be discarded incorrectly. In conclusion, this material achieved the good removal of this studied contaminant and became an economical, viable, and ecologically viable material.
Citation: Recycling
PubDate: 2024-06-23
DOI: 10.3390/recycling9040052
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 53: Sludge-Based Superparamagnetic Nano-Sorbent
Functionalized by Lanthanum Silicate Nanorods for Phosphorus Adsorption
and Fertilization
Authors: Qian Zhao, Xiaole Wang, Juan Ren, Wei Wang, Jingtao Xu, Shujuan Meng, Jiarou Jin, Xiaochen Li, Yuyang Fu, Kechao Han, Ruimin Mu, Xinyi Li, Renbo Zhao, Hongbo Wang, Feiyong Chen
First page: 53
Abstract: Phosphorus (P) recovery from wastewater is considered to be a positive human intervention towards sustainable P use in the global P cycle. This study investigated the feasibility of synthesizing a superparamagnetic nano-sorbent that was functionalized by lanthanum silicate nanorods (NRLa-Si) using drinking water treatment sludge (DWTS), evaluating both its P adsorption capacity and fertilization effect. The DWTS-based La-modified P nano-sorbent (P-sorbent D) exhibited complicated but single-layer-dominant adsorption for phosphate, with a maximum adsorption capacity up to 26.8 mg/g, which was superior to that of most of the similar sludge-based P-sorbent. The NRLa-Si-modified P-sorbent D was identified with several characterization techniques and the leaching metal elements from the nano-sorbent were tested, which were below the limits proposed by the Food and Agriculture Organization of the United Nations. In addition, the growth and vigorousness of Arabidopsis thaliana indicated that the exhausted P-sorbent D could be used as a potential water-soluble moderate-release P fertilizer, which was also confirmed by the well-fitted P uptake model and the P desorption pattern from the sorbent–fertilizer. The doped lanthanum silicate nanorods could play the dual role of P complexation enhancement and health/growth promotion. In light of this, this study proposed a new way of reclaiming DWTS as a P-sorbent for fertilization, offering new insights into the path toward “closing the P loop”.
Citation: Recycling
PubDate: 2024-06-24
DOI: 10.3390/recycling9040053
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 54: Selective Recovery of Tin from Electronic
Waste Materials Completed with Carbothermic Reduction of Tin (IV) Oxide
with Sodium Sulfite
Authors: Wojciech Hyk, Konrad Kitka
First page: 54
Abstract: A new approach for the thermal reduction of tin dioxide (SnO2) in the carbon/sodium sulfite (Na2SO3) system is demonstrated. The process of tin smelting was experimentally optimized by adjusting the smelting temperature and amounts of the chemical components used for the thermal reduction of SnO2. The numbers obtained are consistent with the thermodynamic characteristics of the system and molar fractions of reactants derived from the proposed mechanism of the SnO2 thermal reduction process. They reveal that the maximum yield of tin is obtained if masses of C, Na2SO3 and SnO2 are approximately in the ratio 1:2:3 and the temperature is set to 1050 °C. The key role in the suggested mechanism is the thermal decomposition of Na2SO3. It was deduced from the available experimental data that the produced sulfur dioxide undergoes carbothermic reduction to carbonyl sulfide—an intermediate product involved in the bulk reduction of SnO2. Replacing sodium sulfite with sodium sulfate, sodium sulfide and even elemental sulfur practically terminated the production of metallic tin. The kinetic analysis was focused on the determination of the reaction orders for the two crucial reactants involved in the smelting process.
Citation: Recycling
PubDate: 2024-06-26
DOI: 10.3390/recycling9040054
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 55: Quantifying Recycled Construction and
Demolition Waste for Use in 3D-Printed Concrete
Authors: Wibke De Villiers, Mwiti Mwongo, Adewumi John Babafemi, Gideon Van Zijl
First page: 55
Abstract: Despite extensive regulations, the systemic under-reporting of construction and demolition waste generation rates pervades the South African waste sector due to the extensive and active informal waste management practices that are typical of developing countries. This study merges the rapid development of high-technology 3D-printed concrete (3DPC) with the increasing pressure that the built environment is placing on both natural resource consumption and landfill space due to construction and demolition waste (CDW) by establishing an inventory of CDW that is suitable for use in 3DPC in South Africa. This is an essential step in ensuring the technical, economic, and logistical viability of using CDW as aggregate or supplementary cementitious materials in 3DPC. Of the methods considered, the lifetime material analysis and per capita multiplier methods are the most appropriate for the context and available seed data; this results in CDW estimates of 24.3 Mt and 12.2 Mt per annum in South Africa, respectively. This range is due to the different points of estimation for the two methods considered, and the per capita multiplier method provides an inevitable underestimation. In order to contextualise the estimated availability of CDW material for use in concrete in general, the demand for coarse and fine aggregate and supplementary cementitious material in South Africa is quantified as 77.9 Mt. This overall annual demand far exceeds the estimated CDW material (12.2–24.3 Mt) available as an alternative material source for concrete.
Citation: Recycling
PubDate: 2024-06-28
DOI: 10.3390/recycling9040055
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 56: The Use of Nonmetallic Fraction Particles
with the Double Purpose of Increasing the Mechanical Properties of
Low-Density Polyethylene Composite and Reducing the Pollution Associated
with the Recycling of Metals from E-Waste
Authors: Rubén Flores-Campos, Rogelio Deaquino-Lara, Mario Rodríguez-Reyes, Roberto Martínez-Sánchez, Rosa Hilda Estrada-Ruiz
First page: 56
Abstract: A restorative process, where the nonmetallic fraction from e-waste printed circuit boards is reused as a raw material for the conformation of a new polymer matrix composite with increased properties favoring its industrial applications, is proposed with a zero residues approach. Low density polyethylene pellets and nonmetallic fraction particles were mixed, and due to the generation of static electricity during the mixing process, the nonmetallic particles became attached to the polyethylene pellets; the blended material was fed into a screw extruder, producing filaments of the new composite. Mechanical properties increased as the particles content increased, presenting an ultimate tensile strength going from 20 for the raw low-density polyethylene to more than 60 MPa, and a yield strength that goes from 10 to 50 MPa on the composite with 6.0 wt.% particles. Also, the flammability of the composite improved, reducing its linear burning rate and increasing the time between detachment of two consecutive drops. Nonmetallic fraction particles were oriented in the extrusion direction and had a good adhesion with the polyethylene matrix. These composites can be employed for the production of prototypes using additive manufacture.
Citation: Recycling
PubDate: 2024-07-03
DOI: 10.3390/recycling9040056
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 57: Investigation of the Effectiveness of Barrier
Layers to Inhibit Mutagenic Effects of Recycled LDPE Films, Using a
Miniaturized Ames Test and GC-MS Analysis
Authors: Lukas Prielinger, Smarak Bandyopadhyay, Eva Ortner, Martin Novak, Tanja Radusin, Steffen Annfinsen, Nusrat Sharmin, Bernhard Rainer, Marit Kvalvåg Pettersen
First page: 57
Abstract: To fulfil the European Green Deal targets and implement a circular economy, there is an urgent need to increase recycling rates of packaging materials. However, before recycled materials can be used in food contact applications, they must meet high safety standards. According to the European Food Safety Authority (EFSA), a worst-case scenario must be applied and unknown substances must be evaluated as being potentially genotoxic. The Ames test, which detects direct DNA-reactive effects, together with chromatographic analysis is very promising to complement risk assessment. This study aims to evaluate the effectiveness of functional barriers in ten different samples, including virgin and recycled LDPE foils. FT-IR analysis did not show major differences between virgin and recycled films. Light microscopy revealed differences in quality and an increased number of particles. GC-MS analysis detected and quantified 35 substances, including eight unknowns. Using a miniaturized version of the Ames test, four of ten samples tested positive in two individual migrates up to a dilution of 12.5%. All virgin LDPE materials tested negative; however, recycled material F showed an increased mutagenic activity, with an n-fold induction up to 28. Samples with functional barriers lowered migration and reduced mutagenicity. Nonetheless, further investigations are needed to identify possible sources of contamination.
Citation: Recycling
PubDate: 2024-07-15
DOI: 10.3390/recycling9040057
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 58: A New Recycling Method through Mushroom
Cultivation Using Food Waste: Optimization of Mushroom Bed Medium Using
Food Waste and Agricultural Use of Spent Mushroom Substrates
Authors: Babla Shingha Barua, Ami Nigaki, Ryota Kataoka
First page: 58
Abstract: Food waste is generated in large amounts locally and globally, and requires expenditure for disposal. However, it has high nutritional value and almost no toxic components. Therefore, it can be returned to mushroom mediums for further use, leading to food waste circulation. Though disposing of spent mushroom substrate (SMS) after harvesting is an additional problem, there have been increased efforts to compost it and apply it to the soil for growing vegetables. This study, therefore, aimed to optimize (1) mushroom spawn production with rice hull, (2) mushroom substrates using food waste to accelerate food waste recycling, and (3) the utilization of SMS as an organic fertilizer. An optimal substrate composition and high yield were obtained at 120–140 g of food waste per bag among substrates from Pleorutus ostreatus and Pleorutus citrinopileatus; therefore, using a high ratio of food waste in the mushroom mediums was achieved. On the other hand, the SMS of P. citrinopileatus demonstrated higher plant biomass growth, at 36 g, than that of P. ostreatus, at 21.2 g, in a treatment using SMS + okara. The present discovery is that people may be encouraged to be mindful of food loss by the delivery of mushrooms and plants grown from agro/food waste to the dining table, and this circular system may therefore be used as a key resource in mushroom and plant cultivation and to achieve a zero-emission cycle.
Citation: Recycling
PubDate: 2024-07-15
DOI: 10.3390/recycling9040058
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 59: Recent Developments in Technology for Sorting
Plastic for Recycling: The Emergence of Artificial Intelligence and the
Rise of the Robots
Authors: Cesar Lubongo, Mohammed A. A. Bin Daej, Paschalis Alexandridis
First page: 59
Abstract: Plastics recycling is an important component of the circular economy. In mechanical recycling, the recovery of high-quality plastics for subsequent reprocessing requires plastic waste to be first sorted by type, color, and size. In chemical recycling, certain types of plastics should be removed first as they negatively affect the process. Such sortation of plastic objects at Materials Recovery Facilities (MRFs) relies increasingly on automated technology. Critical for any sorting is the proper identification of the plastic type. Spectroscopy is used to this end, increasingly augmented by machine learning (ML) and artificial intelligence (AI). Recent developments in the application of ML/AI in plastics recycling are highlighted here, and the state of the art in the identification and sortation of plastic is presented. Commercial equipment for sorting plastic recyclables is identified from a survey of publicly available information. Automated sorting equipment, ML/AI-based sorters, and robotic sorters currently available on the market are evaluated regarding their sensors, capability to sort certain types of plastics, primary application, throughput, and accuracy. This information reflects the rapid progress achieved in sorting plastics. However, the sortation of film, dark plastics, and plastics comprising multiple types of polymers remains challenging. Improvements and/or new solutions in the automated sorting of plastics are forthcoming.
Citation: Recycling
PubDate: 2024-07-15
DOI: 10.3390/recycling9040059
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 60: Concentration of Silver from Recycling of
Fine Powder of Wasted Videogame Printed Circuit Boards through Reverse
Froth Flotation and Magnetic Separation Processes
Authors: Rubén Flores-Campos, Rosa Hilda Estrada-Ruiz, Mario Rodríguez-Reyes, Diego Martínez-Carrillo, Antonia Martínez-Luévanos
First page: 60
Abstract: Electronic waste stream grows day by day; printed circuit boards are a kind of solid waste that accounts for 6% of electronic waste. When these are discarded, they can cause soil, water, and air contamination; however, if recycled, these can be considered as a secondary source of metals. Physical comminution of printed circuit boards generates particles with sizes smaller than 250 µm, which are typically not included in the recycling process because they are considered as dust and unvaluable; nevertheless, precious and base metals can be found in these particles. The concentration of metals like silver, among others, from these particles can be achieved by reverse froth flotation in a flotation column followed by magnetic separation of the tails products. A mass balance of the flotation column feed, concentrate, and tails indicates that using a pulp modified with 5 ppm methyl isobutyl carbinol plus 5 g/ton oleic acid (both biodegradable reagents), the concentration of the products improved, resulting in recoveries of 86.13 and 13.87% in the concentrate and tails zones, respectively, with a grade of 74.4% in the tails flow. Magnetic separation of the tails product increases slightly the concentration of silver, reaching a silver grade of 74.5%, a recovery amount similar to those obtained employing complex and environmentally unfriendly processes.
Citation: Recycling
PubDate: 2024-07-22
DOI: 10.3390/recycling9040060
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 61: An Investigation into Sustainable Solutions:
Utilizing Hydrated Lime Derived from Oyster Shells as an Eco-Friendly
Alternative for Semiconductor Wastewater Treatment
Authors: Hye-Jin Lee, Sang-Eun Lee, Seokhwi Kim
First page: 61
Abstract: Due to its acidic nature and high fluoride concentration, hydrated lime (Ca(OH)2) is commonly used for neutralization and fluoride control in semiconductor wastewater treatment. This study investigated the efficacy of treating high fluoride-containing wastewater using hydrated lime derived from oyster shells as an alternative to limestone. Overall, the characteristics of removing pollutants in acidic wastewater using shell-based hydrated lime showed similar patterns to hydrated lime from limestone. The treatment efficiency was 50% or less under theoretical Ca/F molar ratio (=0.5) conditions for the formation of fluorite (CaF2), while the fluorine removal rate reached 99% under somewhat higher Ca/F conditions due to the influence of ionic components in the wastewater. Interestingly, chloride content did not increase even in the initial reaction stages, in contrast to our concerns about oyster shells generally containing salt to a certain extent due to their growth in seawater; instead, the chloride concentration decreased over time, similar to nitrate (NO3−). In controlling fluoride in wastewater, surpassing the theoretical Ca/F molar ratio, particularly considering the presence of other anionic species such as SO4²− and PO4³−, the optimal Ca/F ratio for fluoride removal was found to be 1.59. This value is approximately 16% lower than the calculated value (Ca/F = 1.85) when accounting for other anions. X-ray diffraction results confirmed the presence of CaSO4, Ca3(PO4)2, and CaF2 in the precipitate recovered after the reaction, indicating the effective removal of ionic contaminants. This observation suggests that oyster shell-derived hydrated lime could serve as a viable calcium resource for treating acidic wastewater and represents a potential alternative to traditional limestone-based methods.
Citation: Recycling
PubDate: 2024-07-26
DOI: 10.3390/recycling9040061
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 62: Environmental and Economic Forecast of the
Widespread Use of Anaerobic Digestion Techniques
Authors: Andrey Kiselev, Elena Magaril, Ramona Giurea
First page: 62
Abstract: The concept of the circular economy represents the most relevant mainstream approach to reducing the negative environmental impact of waste. Anaerobic digestion has proved to be one of the leading and widely adopted techniques for sewage sludge treatment under the principles of the circular economy. The purpose of this study is to forecast environmental and economic indicators through modeling the extensive utilization of biogas technologies with a case study of an administrative territorial unit. The proposed methodological framework involves the use of averaged specific indicators and is based on the relationship between inhabitants, waste generation rates, biogas yield, greenhouse gas emission mitigation and biogas energy potential. The widespread use of anaerobic digestion techniques according to the proposed methodology in the instant scenario will ensure the biogas yield of 10 million Nm3 within the considered administrative territory unit with a population of 4.2 million P.E., which ultimately can be expressed in electricity and thermal generation potential of 20.8 and 24.8 million kWh*y, respectively, annual greenhouse gas elimination of 119.6 thousand tons of CO2 equivalent and capital investment attraction of EUR 65.18 million. Furthermore, all sewage sludge will be subjected to disinfection and stabilization procedures to ensure its safe utilization. The findings of this study offer an opportunity for a wide range of stakeholders to assess the environmental and economic benefits of the widespread adoption of biogas technologies. The developed methodology can be utilized to inform management decisions through the use of the instant and scenario forecasts.
Citation: Recycling
PubDate: 2024-07-26
DOI: 10.3390/recycling9040062
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 63: Circular Economy in Practice: A Literature
Review and Case Study of Phosphogypsum Use in Cement
Authors: Girts Bumanis, Danutė Vaičiukynienė, Tatjana Tambovceva, Liga Puzule, Maris Sinka, Dalia Nizevičienė, Ignacio Villalón Fornés, Diana Bajare
First page: 63
Abstract: The utilization of waste generated from industrial production is a burden to overcome for society to reach a circular economy. Usually, production waste is associated with low-quality materials compared to its natural counterparts. In some cases, high-purity materials are generated, while different hazardous substances such as heavy metals, radioactive elements, or organic chemical substances are pollutants that often limit the materials’ further application. One such material that has accumulated for decades is phosphogypsum (PG). The extraction of fertilizers from metamorphous rocks results in large quantities of PG. Until now, PG has been deposited in large stockpiles near the production plant, causing problems for the environment in the surrounding area. However, the chemical composition of PG places it as a high-purity artificial gypsum material, which means that it could be used as a substitution or supplementary material in gypsum-based material production. The concerns, with respect to both legislation and prevailing prejudices in society, about its impurities strongly limit its application. This manuscript reviews current research practices for the effective use of PG and analyzes the importance of the circular economy. A life cycle assessment of current state-of-the-art technologies regarding PG application is proposed.
Citation: Recycling
PubDate: 2024-07-27
DOI: 10.3390/recycling9040063
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 64: Reverse Logistics and the Circular Economy: A
Study before and after the Implementation of the National Solid Waste
Policy in Brazil
Authors: Elias Carlos Aguirre Rodríguez, Cecilia Toledo Hernández, Elen Yanina Aguirre-Rodríguez, Aneirson Francisco da Silva, Fernando Augusto Silva Marins
First page: 64
Abstract: This article analyzes Reverse Logistics (RL) practices associated with the concept of Circular Economy (CE), comparing studies conducted before and after the implementation of the National Solid Waste Policy (NSWP) in Brazil. Data from companies in the Sul Fluminense region were analyzed using the Analytic Hierarchy Process to prioritize RL practices and identify those related to CE. The research included companies from nine Brazilian economic sectors that engage in some form of RL. The comparison of results aimed to evaluate the influence of the NSWP on these practices, with data analyzed using the Super Decisions software (version 3.2) to establish priorities and aggregate them using the Aggregating Individual Priorities method. It was observed that the implementation of the NSWP in 2010 emphasized the importance of sustainability. Although the concept of CE is recent, its operationalization is based on consolidated RL practices such as recycling, remanufacturing, and material reuse. The study provides insights to optimize and expand these practices, facilitating the transition from a linear economy to a circular one.
Citation: Recycling
PubDate: 2024-08-02
DOI: 10.3390/recycling9040064
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 65: Production of Volatile Fatty Acids from
Cheese Whey and Their Recovery Using Gas-Permeable Membranes
Authors: Beatriz Molinuevo-Salces, Viviane da Silva-Lacerda, María Cruz García-González, Berta Riaño
First page: 65
Abstract: The use of anaerobic fermentation to produce volatile fatty acids (VFAs) is an environmentally sustainable alternative for cheese whey (CW) valorization. This study evaluates the effect of pH control on the conversion of organic matter to VFAs from CW and assesses VFA recovery using a novel approach based on gas-permeable membranes. VFA bioconversion and composition were studied with initial and sequential control of pH, both in acidic and alkaline conditions. Bioconversion efficiencies for assays with initial pH control were 36% and 45% for acidic and alkaline conditions, respectively. Sequential control of pH resulted in an increase in bioconversion to 54% under acidic conditions. Under acidic conditions, a variety of VFA was produced (mainly butyric, acetic, and propionic acids), while under alkaline conditions the majority was acetic acid. VFA recovery using a novel system of tubular gas-permeable membranes accounted for 15% and 100% of the total VFA from effluent 1 (butyric, acetic, and propionic acids) and effluent 2 (mainly acetic acid), respectively.
Citation: Recycling
PubDate: 2024-08-05
DOI: 10.3390/recycling9040065
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 66: Silicon Kerf Recovery via Acid Leaching
Followed by Melting at Elevated Temperatures
Authors: Tinotenda Mubaiwa, Askh Garshol, Alexander Azarov, Jafar Safarian
First page: 66
Abstract: The aim of this work was to study the purification of silicon kerf loss waste (KLW) by a combination of single-acid leaching followed by inductive melting at high temperatures with an addition of fluidized bed reactor (FBR) silicon granules. The KLW indicated an average particle size (D50) of approximately 1.6 µm, and a BET surface area of 30.4 m2/g. Acid leaching by 1 M HCl indicated significant removal of impurities such as Ni (77%), Fe (91%) and P (75%). The combined two-stage treatment resulted in significant removal of the major impurities: Al (78%), Ni (79%), Ca (85%), P (92%) and Fe (99%). The general material loss during melting decreased with an increasing amount of FBR silicon granules which aided in the melting process and indicated better melting. It was observed that the melting behavior of the samples improved as the temperature increased, with complete melting being observed throughout the crucibles at the highest temperature (1800 °C) used, even without any additives. At lower temperatures (1600 °C–1700 °C) and lower FBR-Si (<30 wt.%) additions, the melting was incomplete, with patches of molten silicon and a lot of surface oxidation as confirmed by both visual observation and electron microscopy. In addition, it was indicated that more reactive and volatile elements (Ga, Mg and P) compared to silicon are partially removed in the melting process (51–87%), while the less reactive elements end up in the final silicon melt. It was concluded that if optimized, the combined treatment of single-acid leaching and inductive melting with the addition of granular FBR silicon has great potential for the recycling of KLW to solar cells and similar applications. Moreover, the application of higher melting temperatures is accompanied by a higher silicon yield of the process, and the involved mechanisms are presented.
Citation: Recycling
PubDate: 2024-08-08
DOI: 10.3390/recycling9040066
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 67: Quality-Driven Allocation Method to Promote
the Circular Economy for Plastic Components in the Automotive Industry
Authors: Ilka Pfisterer, Roman Rinberg, Lothar Kroll, Niels Modler
First page: 67
Abstract: In recent years, the development of a circular economy of plastic products in the automotive industry has been pursued by original equipment manufacturers (OEMs) not only due to strategic premises by the European Commission but also due to an increasing demand by customers. To achieve a circular economy, high-quality recyclates are needed. However, in the current situation, there is a discrepancy between the low-quality recyclate that is available on the market and the high-quality recyclate that is demanded by manufacturers. To increase the quality of recyclate on the market, a standardized process to reward a ‘design-for-recycling’ approach at the product development stage is needed. This paper proposes an allocation method that takes into account material compositions and common recycling processes and incentivizes the preservation of high-quality grades of recyclate based on grade purity.
Citation: Recycling
PubDate: 2024-08-09
DOI: 10.3390/recycling9040067
Issue No: Vol. 9, No. 4 (2024)
- Recycling, Vol. 9, Pages 32: Enhancing the Strength and the Environmental
Performance of Concrete with Pre-Treated Crumb Rubber and Micro-Silica
Authors: M. R. Rajagopal, Jyothikumari Ganta, Yashwanth Pamu
First page: 32
Abstract: Dumped non-biodegradable tires present a significant environmental threat, with overflowing landfills and associated health risks highlighting the urgency of tire waste disposal. Current disposal methods, such as stacking tires in open spaces, exacerbate the problem. The large-scale recycling of tire rubber waste offers environmental benefits. This study examines the effects of pre-treatment using NaOH and micro-silica as a mineral admixture on the mechanical strength of crumb rubber concrete (CRC) with partial replacement of natural sand. Samples of M20 and M30 grade were prepared with varying levels of crumb rubber (CR) replacement and evaluated at 28 days. CRC prepared with pre-treated NaOH solution and micro-silica showed improved workability and strength compared to conventional concrete and untreated CRC, with the highest strength observed for 5% CR replacement using micro-silica. Predictive models and micro-structural analysis validated these findings. Life Cycle Assessment (LCA) using OpenLCA v2.10 software and the ecoinvent database revealed that incorporating micro-silica into CRC did not significantly increase environmental impacts, compared to conventional concrete across different mixes.
Citation: Recycling
PubDate: 2024-04-24
DOI: 10.3390/recycling9030032
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 33: Evaluation of Thermoplastic Starch
Contamination in the Mechanical Recycling of High-Density Polyethylene
Authors: Antonio Cascales, Cristina Pavon, Santiago Ferrandiz, Juan López-Martínez
First page: 33
Abstract: This research highlights the importance of addressing bioplastic contamination in recycling processes to ensure the quality of recycled material and move towards a more sustainable circular economy. Polyethylene (PE) is a conventional plastic commonly used in packaging for which large amounts of waste are produced; therefore, PE is generally recycled and has an established recycling process. However, the contamination of biodegradable polymers in the PE waste stream could impact recycling. This study, therefore, focuses on polyethylene (PE) that has been polluted with a commercial thermoplastic starch polymer (TPS), as both materials are used to produce plastic films and bags, so cross-contamination is very likely to occur in waste separation. To achieve this, recycled PE was blended with small quantities of the commercial TPS and processed through melt extrusion and injection molding, and it was further characterized. The results indicate that the PE-TPS blend lacks miscibility, evidenced by deteriorated microstructure and mechanical properties. In addition, the presence of the commercial TPS affects the thermal stability, oxidation, and color of the recycled PE.
Citation: Recycling
PubDate: 2024-04-26
DOI: 10.3390/recycling9030033
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 34: Recycling of Egyptian Shammi Corn Stalks for
Maintaining Sustainable Cement Industry: Scoring on Sustainable
Development Goals
Authors: Fajr Qasem, Mahmoud Sharaan, Manabu Fujii, Mahmoud Nasr
First page: 34
Abstract: This study focuses on recycling Shammi corn stalks in the cement industries, further avoiding air and soil pollution caused by their improper disposal. This crop residue was thermally treated at 700 °C for 2 h under an oxygen-rich environment to produce Shammi corn stalk ash (SCSA). This SCSA was used as a cement replacement material (2–10%, w/w), whereas the control sample included only cement. The compressive strength values for the 4% (w/w) replacement ratio at 2-, 7-, and 28-day ages were greater than those for the control by 26.5%, 15.8%, and 11.4%, respectively. This 4% (w/w) also maintained a better flexural strength than other mixtures, with proper initial and final setting times (135 and 190 min), workability (18.5 cm), and water consistency (27.5%). These mechanical/physical properties were integrated with socio-enviro-economic data collected from experts through a pairwise comparison questionnaire, forming the inputs of a multi-criteria decision-making (MCDM) model. Recycling SCSA in the cement-manufacturing process attained positive scores in the achievement of the three pillars of sustainable development, revealing an overall score greater than the control. Hence, the study outcomes could be essential in developing green concrete, cement blocks, and mortar, based on the sustainable development goals (SDGs) agenda.
Citation: Recycling
PubDate: 2024-04-26
DOI: 10.3390/recycling9030034
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 35: Considering Grouped or Individual Non-Methane
Volatile Organic Compound Emissions in Life Cycle Assessment of Composting
Using Three Life Cycle Impact Assessment Methods
Authors: Ben Joseph, Heinz Stichnothe
First page: 35
Abstract: Composting is a waste management practice that converts organic waste into a product that can be used safely and beneficially as a bio-fertiliser and soil amendment. Non-methane volatile organic compounds (NMVOCs) from composting are known to cause damage to human health and the environment. The impact of waste management on the environment and workers is recognised as a growing environmental and public health concern. Measurements of NMVOCs emitted during composting have been carried out only in a few studies. NMVOC emissions are typically reported as a group rather than as species or speciation profiles. Recognising the need to investigate the issues associated with NMVOCs, the objective of this study is to estimate variation in life cycle assessment (LCA) results when NMVOCs are considered individual emissions compared to grouped emissions and to compare midpoint and endpoint life cycle impact assessment (LCIA) methods. In general, the ReCiPe 2016 LCIA method estimated the highest impact from the composting process in comparison to IMPACT World+ and EF 3.0 for the impact categories of ozone formation, stratospheric ozone depletion, and particulate matter formation. For ReCiPe 2016 and IMPACT World+, the NMVOC emissions were not linked to human toxicity characterisation factors, meaning that the contribution from NMVOC towards human health risks in and around composting facilities could be underestimated. Using individual NMVOCs helps to additionally estimate the impacts of composting on freshwater ecotoxicity and human carcinogenic and non-carcinogenic toxicity potential. If ecotoxicity or toxicity issues are indicated, then LCA should be accompanied by suitable risk assessment measures for the respective life cycle stage.
Citation: Recycling
PubDate: 2024-04-29
DOI: 10.3390/recycling9030035
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 36: Recycling of Rhenium from Superalloys and
Manganese from Spent Batteries to Produce Manganese(II) Perrhenate
Dihydrate
Authors: Katarzyna Leszczyńska-Sejda, Arkadiusz Palmowski, Michał Ochmański, Grzegorz Benke, Alicja Grzybek, Szymon Orda, Karolina Goc, Joanna Malarz, Dorota Kopyto
First page: 36
Abstract: This work presents the research results on the development of an innovative, hydrometallurgical technology for the production of manganese(II) perrhenate dihydrate from recycled waste. These wastes are scraps of Ni-based superalloys containing Re and scraps of Li–ion batteries containing Mn—specifically, solutions from the leaching of black mass. This work presents the conditions for the production of Mn(ReO4)2·2H2O. Thus, to obtain Mn(ReO4)2·2H2O, manganese(II) oxide was used, precipitated from the solutions obtained after the leaching of black mass from Li–ion batteries scrap and purified from Cu, Fe and Al (pH = 5.2). MnO2 precipitation was carried out at a temperature < 50 °C for 30 min using a stoichiometric amount of KMnO4 in the presence of H2O2. MnO2 precipitated in this way was purified using a 20% H2SO4 solution and then H2O. Purified MnO2 was then added alternately with a 30% H2O2 solution to an aqueous HReO4 solution. The reaction was conducted at room temperature for 30 min to obtain a pH of 6–7. Mn(ReO4)2·2H2O precipitated by evaporating the solution to dryness was purified by recrystallization from H2O with the addition of H2O2 at least twice. Purified Mn(ReO4)2·2H2O was dried at a temperature of 100–110 °C. Using the described procedure, Mn(ReO4)2·2H2O was obtained with a purity of >99.0%. This technology is an example of the green transformation method, taking into account the 6R principles.
Citation: Recycling
PubDate: 2024-04-30
DOI: 10.3390/recycling9030036
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 37: Recent Trends of Recycling and Upcycling of
Polymers and Composites: A Comprehensive Review
Authors: Christina Podara, Stefania Termine, Maria Modestou, Dionisis Semitekolos, Christos Tsirogiannis, Melpo Karamitrou, Aikaterini-Flora Trompeta, Tatjana Kosanovic Milickovic, Costas Charitidis
First page: 37
Abstract: This review article gathers the most recent recycling technologies for thermoset and thermoplastic polymers. Results about existing experimental procedures and their effectiveness are presented. For thermoset polymers, the review focuses mainly on fibre-reinforced polymer composites, with an emphasis on epoxy-based systems and carbon/glass fibres as reinforcement, due to the environmental concerns of their end-of-life management. Thermal processes (fluidised bed, pyrolysis) and chemical processes (different types of solvolysis) are discussed. The most recent combined processes (microwave, steam, and ultrasonic assisted techniques) and extraordinary recycling attempts (electrochemical, biological, and with ionic liquids) are analysed. Mechanical recycling that leads to the downgrading of materials is excluded. Insights are also given for the upcycling methodologies that have been implemented until now for the reuse of fibres. As for thermoplastic polymers, the most state-of-the-art recycling approach for the most common polymer matrices is presented, together with the appropriate additivation for matrix upcycling. Mechanical, chemical, and enzymatic recycling processes are described, among others. The use of fibre-reinforced thermoplastic composites is quite new, and thus, the most recent achievements are presented. With all of the above information, this extensive review can serve as a guide for educational purposes, targeting students and technicians in polymers recycling.
Citation: Recycling
PubDate: 2024-05-06
DOI: 10.3390/recycling9030037
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 38: Green Valorization of Waste Plastics to
Graphene as an Upcycled Eco-Friendly Material for Advanced Gas Sensing
Authors: Prince Oppong Amoh, Marwa Elkady, Mahmoud Nasr, Hassan Shokry
First page: 38
Abstract: The valorization technique successfully transformed waste polyethylene terephthalate (PET) into valuable carbon nanomaterial (CN)/graphene, while doped and undoped ZnO nanopowders were synthesized via sol–gel methods. Utilizing XRD, BET, TEM, EDX, FTIR, and TGA analyses, the synthesis of sp2 2D sheet, pristine, and doped ZnO nanostructures was confirmed. Solid-state gas sensor devices, tested under 51% relative humidity (RH), 30 °C ambient temperature, and 0.2 flow rate, exhibited a 3.4% enhanced response to H2 gas compared to CO2 at 50 ppm concentrations over time. Notably, the ZnO/CN sensor surpassed CN and ZnO alone, attributed to CN dopant integration with decreasing order of response performance as ZnO/CN > CN > ZnO. This study underscores the efficacy of valorization techniques in generating high-value carbon nanomaterials and their efficacy in bolstering gas sensor performance, with ZnO/CN demonstrating superior response capabilities.
Citation: Recycling
PubDate: 2024-05-13
DOI: 10.3390/recycling9030038
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 39: Rapid Waste Motor Oil Conversion into
Diesel-Range Hydrocarbons Using Hydrochar as Catalyst: Kinetic Study and
Product Characterization
Authors: Herman A. Murillo, Evelyn Juiña, Karla Vizuete, Alexis Debut, Daniel Echeverría, Sebastian Taco-Vasquez, Sebastian Ponce
First page: 39
Abstract: Herein, raw and alkali-treated hydrochars from biomass waste are prepared as a highly active catalyst for the conversion of waste motor oil into diesel-like fuels. Among all materials, hydrochar obtained at 250 °C and subsequent alkali activation with KOH showed a 600% improvement of the kinetic constant from 0.0088 to 0.0614 m−1. Conversion values at the same conditions were also improved from 66 to 80% regarding thermal and catalytic cracking, respectively. Moreover, the activation energy was also reduced from 293 to 246 kJ mol−1 for thermal and catalytic cracking, respectively. After characterization, the enhanced catalytic activity was correlated to an increased surface area and functionalization due to the alkali activation. Finally, the liquid product characterization demonstrated that catalytic cracking is more effective than thermal cracking for producing hydrocarbons in the diesel range. In particular, hydrochar-based catalysts are suggested to promote the formation of specific hydrocarbons so that the carbon distribution can be tailored by modifying the hydrothermal treatment temperature.
Citation: Recycling
PubDate: 2024-05-17
DOI: 10.3390/recycling9030039
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 40: Valorizing Fruit and Vegetable Waste: The
Untapped Potential for Entrepreneurship in Sub-Saharan Africa—A
Systematic Review
Authors: Grace Okuthe
First page: 40
Abstract: Valorizing food waste (FW) in sub-Saharan Africa (SSA) can enhance the efficiency of limited resources, make healthy diets more affordable, and foster the creation of innovative enterprises. The vast quantities of FW from the agri-food chain significantly threaten food security. To address this issue and maximize potential environmental and socio-economic benefits, valorizing waste, a value-adding process for waste materials, has emerged as a sustainable and efficient strategy. Valorizing FW reduces greenhouse gas emissions, mitigates climate change, enhances resource efficiency, and improves planetary health. As a pivotal player in the transition toward the circular economy, this study investigates the potential of converting FW into value-added products, offering entrepreneurial opportunities for SSA’s unemployed youth. A systematic literature review is conducted to identify and filter relevant articles over five years by applying inclusion and exclusion criteria. A total of 33 articles were included for in-depth analysis to address the study’s aim. The findings highlight a range of value-added products derived from FW, including renewable energy sources, nutraceuticals, and heavy metal adsorbents. These products present promising entrepreneurial prospects within SSA. Nonetheless, overcoming barriers to FW valorization adoption is crucial for fully realizing its potential as a profitable business avenue.
Citation: Recycling
PubDate: 2024-05-17
DOI: 10.3390/recycling9030040
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 41: Effect of Recycled Concrete Aggregate
Addition on the Asphalt Mixtures Performance: ITZ Area, Microstructure,
and Chemical Analysis Perspectives
Authors: Hanaa Khaleel Alwan Al-Bayati, Waleed Jadaa, Susan L. Tighe
First page: 41
Abstract: The importance of environmental consciousness and sustainability is increasing among transportation governing bodies worldwide. Many government bodies are concerned with maximizing the usage of recycled substances in road construction. Therefore, assessing the effect of recycled materials consumption is essential, mainly when designing new ‘green’ pavement types. The primary objective of this study is to investigate the impact of different treatments on improving the interfacial transition zone (ITZ) of coarse recycled concrete aggregate (CRCA) and its application in asphalt mixes. Such an aim is accomplished by enhancing its physical and mechanical characteristics, as well as its microstructure. The surface morphology, chemical composition, and intermix phases of the ITZ area and calcium silicate hydrate (CSH) compounds for CRCA were evaluated using scanning electron microscopy (SEM), an energy-dispersive X-ray analyzer (EDAX), and X-ray diffraction analysis (XRD). The performance of asphalt mixtures that included treated and untreated CRCA was also examined using different tests. It was found that heat treatment is an effective technique for enhancing the ITZ. However, cracks were seen in the mortar of CRCA when exposed to high temperatures (500 °C), which adversely affects the characteristics of the mortar. Acid treatment appeared to be an effective approach for improving the ITZ area. Nevertheless, the treatment that used acetic acid, a weak acid, was more effective than HCl acid, a strong acid. The outcomes revealed that the ITZ microstructure is significantly enhanced under different treatment types; however, microstructure improvements mainly included increased surface homogeneity and CSH compounds and a reduced Ca/Si ratio. It was also found that the asphalt mixtures with different proportions of untreated CRCA exhibited enhanced resistance to rutting. Furthermore, their tensile strength ratio (TSR) values were above the minimal level requirements. Moreover, the asphalt mixture with 30% CRCA, which was treated with various treatment methods, demonstrated a significant improvement in the mixtures’ mechanical properties; therefore, its application is highly successful and an environmentally friendly solution.
Citation: Recycling
PubDate: 2024-05-18
DOI: 10.3390/recycling9030041
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 42: Investigating the Role of Municipal Waste
Treatment within the European Union through a Novel Created Common
Sustainability Point System
Authors: Konstantinos Tsimnadis, Grigorios L. Kyriakopoulos
First page: 42
Abstract: Over the last several decades, the European Union (EU) has championed recycling and sustainable waste management through Directives 2008/98/EC and 2018/851, shaping practices across its member states. Currently, 30% of the EU’s municipal waste is recycled, 19% composted, 23% incinerated, and 23% landfilled. However, regional variations exist within the EU, with Greece and other Mediterranean/Balkan nations favoring landfilling, while Germany and other Western/Central EU nations prioritize recycling and composting, and Nordic countries lean toward incineration. To address these differences, a new sustainability point system was created in order to evaluate and compare all different municipal waste management strategies of EU members. Notably, countries like Germany, the Netherlands, and Sweden score the highest due to low municipal waste generation, high recycling rates (>35%), minimal landfilling (<1%), and significant incineration. In contrast, Cyprus, Malta, and Greece score lower due to landfill reliance and lower recycling rates. Therefore, this study introduces a novel sustainability point system to mitigate disparities, highlighting the need for targeted interventions and policy initiatives at the national and EU levels. By leveraging these insights, policymakers can allocate resources effectively, foster collaboration, and motivate citizens to achieve common environmental goals as well as the Sustainable Development Goals (SDGs).
Citation: Recycling
PubDate: 2024-05-20
DOI: 10.3390/recycling9030042
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 43: Recent Advancements in Material Waste
Recycling: Conventional, Direct Conversion, and Additive Manufacturing
Techniques
Authors: Mandar Golvaskar, Sammy A. Ojo, Manigandan Kannan
First page: 43
Abstract: To improve the microstructure and mechanical properties of fundamental materials including aluminum, stainless steel, superalloys, and titanium alloys, traditional manufacturing techniques have for years been utilized in critical sectors including the aerospace and nuclear industries. However, additive manufacturing has become an efficient and effective means for fabricating these materials with superior mechanical attributes, making it easier to develop complex parts with relative ease compared to conventional processes. The waste generated in additive manufacturing processes are usually in the form of powders, while that of conventional processes come in the form of chips. The current study focuses on the features and uses of various typical recycling methods for traditional and additive manufacturing that are presently utilized to recycle material waste from both processes. Additionally, the main factors impacting the microstructural features and density of the chip-unified components are discussed. Moreover, it recommends a novel approach for recycling chips, while improving the process of development, bonding quality of the chips, microstructure, overall mechanical properties, and fostering sustainable and environmentally friendly engineering.
Citation: Recycling
PubDate: 2024-05-21
DOI: 10.3390/recycling9030043
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 44: Valorization of Spent Mushroom Substrate:
Establishing the Foundation for Waste-Free Production
Authors: Andrew Ravlikovsky, Maria Nazaré Coelho Pinheiro, Lucian Dinca, Vlad Crisan, Lyudmyla Symochko
First page: 44
Abstract: Spent mushroom substrate (SMS), often disregarded as waste despite its abundance in organic matter and mineral micronutrients, has emerged as a valuable resource for diverse applications. While Europe and Asia have witnessed extensive research in this field over the past decade, Ukraine’s exploration remains limited. This study conducts a thorough investigation into SMS recycling and reutilization over a 4-year period. Employing experimental and comparative methods, this research unveils compelling insights into the potential of SMS for reintroduction into the primary production cycle and secondary activities. The main conclusions reveal the success of SMS valorization in the production of additives, fertilizers, and alternative fuels. Furthermore, the application of SMS in agroecosystems significantly enhances the soil biological activity. The integration of these methods into production chains not only yields economic benefits for companies but also fosters environmental stewardship, aligning with waste-free practices and the principles of bioeconomy and sustainability.
Citation: Recycling
PubDate: 2024-05-22
DOI: 10.3390/recycling9030044
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 45: A Comprehensive Review on Use of Wastewater
in the Manufacturing of Concrete: Fostering Sustainability through
Recycling
Authors: Manjunath Maddikeari, Bibhuti Bhusan Das, Ranjitha B. Tangadagi, Suman Roy, Priyanka Bangalore Nagaraj, Manjunatha Lokanahally Ramachandra
First page: 45
Abstract: The primary aim of this review article is to find the influence of wastewater and its characteristics on recycling as an alternative to potable water for concrete preparation. On the other hand, scarcity, and the demand for freshwater for drinking are also increasing day by day around the globe. About a billion tons of freshwater is consumed daily for concrete preparation for various operations such as mixing and curing, to name a few. The rapid development of certain industries such as textile, casting, stone cutting, and concrete production has caused the water supply to be severely affected. Recycling wastewater in concrete offers various potential benefits like resource conservation, environmental protection, cost savings, and enhanced sustainability. This article reviews the effect of various types of wastewater on various physical and chemical properties of wastewater, rheological characteristics, strength, durability, and microstructure properties of concrete. It also explores the potential effects of decomposing agents on enhancing concrete properties. Currently, limited research is available on the use of various types of wastewater in concrete. Hence, there is a need to develop various methods and procedures to ensure that the utilization of wastewater and treated wastewater is carried out in the production of concrete in a sustainable manner. Although wastewater can reduce the workability of fresh concrete, it can also increase its strength and long-term performance of concrete. The use of various types of wastewater, such as reclaimed water and tertiary-treated wastewater, was found to be superior compared to those using industrial- or secondary-treated wastewater. Researchers around the globe agree that wastewater can cause various detrimental effects on the mechanical and physical properties of concrete, but the reductions were not significant. To overcome limited scientific contributions, this article reviews all the available methods of using various types of wastewater to make concrete economically and environmentally friendly. This research also addresses possible challenges with respect to the demand for freshwater and the water crisis.
Citation: Recycling
PubDate: 2024-05-24
DOI: 10.3390/recycling9030045
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 46: Development and Properties of Recycled
Biomass Fly Ashes Modified Mortars
Authors: Julien Hubert, Sophie Grigoletto, Frédéric Michel, Zengfeng Zhao, Luc Courard
First page: 46
Abstract: The production of biomass fly ash has been increasing every year in Europe, reaching 5.5 million tons in 2020. Fly ash produced by burning biomass is not yet accepted in the standards as a substitute material for cement in mortar and concrete. In a first approach, the substitution limit of biomass ash is determined by comparing the mechanical strengths (among others, compressive strength), fresh state properties and hardened properties of mortars produced with fly ash with those of mortars produced with coal fly ash (EN 450-1 and ASTM C618). Masonry and rendering mortars have been designed with different substitution rates of fly ashes from wood combustion in thermal power plants. Although there is an overall decrease in performance, mortars made with biomass ash retain properties that make them suitable for use in masonry (loss of 13% compressive strength for masonry mortars with 10% substitution rate after 90 days) or rendering (loss of 20% compressive strength for rendering mortars with 10% substitution rate after 90 days). Water absorption and porosity (24.1 and 23.7% for masonry and rendering mortars, respectively) are, however, not significantly modified, which potentially contributes to good durability properties.
Citation: Recycling
PubDate: 2024-05-24
DOI: 10.3390/recycling9030046
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 47: Performance Evaluation of Self-Compacting
Concrete Prepared Using Waste Foundry Sand on Engineering Properties and
Life Cycle Assessment
Authors: Ranjitha B. Tangadagi, P. T. Ravichandran
First page: 47
Abstract: The primary objective of this research is to utilize an industrial waste byproduct such as waste foundry sand (WFS) as an alternative for fine aggregate in self-compacting concrete (SCC). This research focuses on the use of WFS in SCC to enhance durability and mechanical properties, to find an alternative for fine aggregate in SCC, to reduce the disposal challenges of WFS, and to make SCC lightweight and environmentally friendly. Initially, WFS was treated with chemical (H2SO4), segregating, and sieving to remove the foreign matter and clay content. For this study, WFS is considered in varying percentages such as 0, 10, 20, 30, 40, and 50. For this investigation, M60 grade SCC is considered as per Indian standards and EFNARC guidelines. After that, this research focuses on tests on various fresh properties of SCC in each batch to find the flowability and passing ability of various mixes prepared using WFS. Similarly, the mechanical properties of SCC such as compressive, flexural, and split tensile strength tests were performed at 7, 28, and 90 day curing periods, respectively. Likewise, durability properties of SCC were found in all the mixes prepared using WFS such as water absorption, sorptivity, resistance to chemical attack, and chloride ion penetration; tests of these properties were performed at 28 and 90 day curing periods, respectively. Based on the experimental investigation of SCC, it was found that WFS can be used in M60 grade SCC as an alternative for fine aggregate up to 30% without compromising much on its properties. Finally, this establishes that using treated WFS in SCC helps in reducing the generation of waste and prevails as a meaningful utilization method. This research will also establish that the use of treated WFS will reduce the density and make SCC a lightweight, green, and sustainable material.
Citation: Recycling
PubDate: 2024-06-01
DOI: 10.3390/recycling9030047
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 48: An Innovative Magnetic Density Separation
Process for Sorting Granular Solid Wastes
Authors: Lin Wang, Peter Rem, Francesco Di Maio, Max van Beek, Gonçalo Tomás
First page: 48
Abstract: Solid waste sorting is an important pre-treatment in recycling to improve the efficiency of material recovery and reduce costs. Motivated by the PEACOC project on metal recovery from solid wastes, an innovative magnetic density separation (MDS) process has been developed for solid waste sorting. It has intrinsic advantages over conventional gravity separation technologies and the previously industrialized MDS process. The new MDS process applies an inclined planar magnet and a horizontal basin containing a static magnetic fluid as the separation medium. A particle sliding phenomenon is identified as a feature that could help the separation. Experiments have been carried out to demonstrate the role of the MDS in concentrating valuable metals in shredded PCBAs and reducing metallic contaminants in plastic fractions of shredded wires. A pilot scale facility is introduced to show the design to achieve continuous production and to reduce the consumption of ferrofluid.
Citation: Recycling
PubDate: 2024-06-03
DOI: 10.3390/recycling9030048
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 49: Adsorption of Eriochrome Black T on Pseudo
Boehmite and Gamma Alumina Synthesized from Drinking Water Treatment
Sludge: A Waste-to-Recycling Approach
Authors: Ibtissam Ballou, Jamal Naja, Zineelabidine Bakher, Sanae Kholtei
First page: 49
Abstract: Eriochrome black T is considered as one of the anionic dyes with potential harmful effects on human health and the environment. Among other processes, adsorption can contribute to the removal of these dyes. In the present study, two adsorbent materials, pseudo-boehmite (γ-AlOOH) and gamma alumina (γ-Al2O3), were synthesized and tested in the removal of the Eriochrome black T molecule (EBT). γ-AlOOH and γ-Al2O3 were obtained by precipitation from NaAlO2 solution at pH = 7, at a temperature of 80 °C, and by the thermal transformation of γ-AlOOH at 800 °C, respectively. In order to gain insights into the structural, chemical, thermal and morphological properties of these materials, numerous analytical techniques were involved, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), differential thermogravimetric–thermal analysis (TGA-DTA), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and specific surface area measurement using the Brunauer–Emmett–Teller (BET) method. Several adsorption parameters were studied, such as the adsorbent dose, initial concentration, pH, contact time and reaction temperature. The kinetic study showed that EBT adsorption follows the pseudo-second-order model. The Langmuir isotherm model revealed a maximum EBT adsorption capacity of 344.44 mg g−1 and 421.94 mg g−1 for γ-AlOOH and γ-Al2O3, respectively. A textural and structural analysis after adsorption highlighted the effective adsorption of the dye.
Citation: Recycling
PubDate: 2024-06-04
DOI: 10.3390/recycling9030049
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 50: Optimization Production of an
Endo-β-1,4-Xylanase from Streptomyces thermocarboxydus Using Wheat
Bran as Sole Carbon Source
Authors: Thi Ngoc Tran, Chien Thang Doan, Thi Kieu Loan Dinh, Thi Hai Ninh Duong, Thi Thuc Uyen Phan, Thi Thuy Loan Le, Trung Dung Tran, Pham Hung Quang Hoang, Anh Dzung Nguyen, San-Lang Wang
First page: 50
Abstract: Xylanases, key enzymes for hydrolyzing xylan, have diverse industrial applications. The bioprocessing of agricultural byproducts to produce xylanase through fermentation approaches is gaining importance due to its significant potential to reduce enzyme production costs. In this work, the productivity of Streptomyces thermocarboxydus TKU045 xylanase was enhanced through liquid fermentation employing wheat bran as the sole carbon source. The maximum xylanase activity (25.314 ± 1.635 U/mL) was obtained using the following optima factors: 2% (w/v) wheat bran, 1.4% (w/v) KNO3, an initial pH of 9.8, an incubation temperature of 37.3 °C, and an incubation time of 2.2 days. Xylanase (Xyn_TKU045) of 43 kDa molecular weight was isolated from the culture supernatant and was biochemically characterized. Analysis through liquid chromatography with tandem mass spectrometry revealed a maximum amino acid identity of 19% with an endo-1,4-β-xylanase produced by Streptomyces lividans. Xyn_TKU045 exhibited optimal activity at pH 6, with remarkable stability within the pH range of 6.0 to 8.0. The enzyme demonstrated maximum efficiency at 60 °C and considerable stability at ≤70 °C. Mg2+, Mn2+, Ba2+, Ca2+, 2-mercaptoethanol, Tween 20, Tween 40, and Triton X-100 positively influenced Xyn_TKU045, while Zn2+, Fe2+, Fe3+, Cu2+, and sodium dodecyl sulfate exhibited adverse impact. The kinetic properties of Xyn_TKU045 were a Km of 0.628 mg/mL, a kcat of 75.075 s−1 and a kcat/Km of 119.617 mL mg−1s−1. Finally, Xyn_TKU045 could effectively catalyze birchwood xylan into xylotriose and xylobiose as the major products.
Citation: Recycling
PubDate: 2024-06-09
DOI: 10.3390/recycling9030050
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 51: Study of the Mechanical and Electrochemical
Performance of Structural Concrete Incorporating Recycled Polyethylene
Terephthalate as a Partial Fine Aggregate Replacement
Authors: Ana Cecilia Espindola-Flores, Michelle Alejandra Luna-Jimenez, Edgar Onofre-Bustamante, Ana Beatriz Morales-Cepeda
First page: 51
Abstract: The extraction of materials, such as sand and gravel, required for the manufacture of concrete results in the overexploitation of natural resources and a large release of CO2 emissions into the environment. Therefore, the search for alternatives to partially replace these aggregates has become an important issue to solve. Nonetheless, the demand for producing sustainable yet high-strength and durable concrete using alternative materials has led concrete technologists to develop high-performance concrete. These novel concretes possess superior engineering properties, such as high durability and ductility, low maintenance costs, high mechanical strength, and prolonged service life. Currently, there is significant interest in the development of concrete–polymer compounds, primarily to improve the mechanical properties of the material. In this context, the present study explores the partial replacement of fine aggregate with recycled Polyethylene terephthalate (R-PET) in different proportions to produce green structural concrete, with the aim of studying its impact on the mechanical and electrochemical properties. The mechanical properties evaluated were the compressive and flexural strengths, while the electrochemical properties were evaluated through the open circuit potential and polarization curves. The results indicated that specimens containing different R-PET percentages as a replacement for fine aggregate showed higher increases in compressive and flexural strengths. It was also found that the presence of R-PET decreased the corrosion rate of the reinforcing steel when seawater was used as the electrolyte.
Citation: Recycling
PubDate: 2024-06-20
DOI: 10.3390/recycling9030051
Issue No: Vol. 9, No. 3 (2024)
- Recycling, Vol. 9, Pages 21: Comparison of Sodium Hydroxide and Sodium
Carbonate as Alkali Catalysts in Ethanol Organosolv Treatment of Cotton
Stalks for the Release of Hydroxycinnamates
Authors: Georgia Papadimitriou, Vassiliki Zarnavalou, Theodoros Chatzimitakos, Dimitrios Palaiogiannis, Vassilis Athanasiadis, Stavros I. Lalas, Dimitris P. Makris
First page: 21
Abstract: Cotton stalks are residual biomass resulting from cotton bud harvesting, and they are composed primarily of lignocellulosic material. This material could be a source of functional polyphenols. To investigate this prospect, this study was undertaken with the view to examining whether an ethanol-based organosolv treatment could be suitable for producing extracts enriched in polyphenolic compounds. To this end, alkali catalysis was employed, and two catalysts, sodium hydroxide and sodium carbonate, were tested. The initial approach based on treatment severity showed that both catalysts may be equally effective in the recovery of polyphenols, yet in most cases studied, no clear trend between treatment severity and total polyphenol yield was recorded. The following study, based on response surface methodology, provided optimized conditions for both treatments, sodium hydroxide and sodium carbonate, where the recommended catalyst concentrations were 0.67 and 4%, respectively. Under a constant temperature of 90 °C and residence time of 300 min, the treatments with sodium hydroxide and sodium carbonate afforded total polyphenol yields of 18.4 ± 1 and 15.6 ± 1.9 mg CAE g−1 DM, respectively, which showed no significant statistical difference (p > 0.05). However, high-performance liquid chromatography analyses revealed that the sodium carbonate-catalyzed treatment produced extract particularly enriched in two hydroxycinnamate derivatives, ferulic and p-coumaric acid. This extract also exhibited increased antioxidant activity. The outcome of this study strongly suggests cotton stalks as a bioresource of functional substances, while mild alkali-catalyzed ethanol organosolv treatment appears to be a very promising technique for effectively delivering hydroxycinnamate-enriched extracts.
Citation: Recycling
PubDate: 2024-03-01
DOI: 10.3390/recycling9020021
Issue No: Vol. 9, No. 2 (2024)
- Recycling, Vol. 9, Pages 22: Measurements of the Permeability Coefficient
of Waste Coal Ash under Hydrostatic Pressure to Identify the Feasibility
of Its Use in Construction
Authors: Barbara Dutka, Katarzyna Godyń, Przemysław Skotniczny, Katarzyna Tokarczyk, Maciej Tram
First page: 22
Abstract: The aim of this research was to measure the filtration properties of waste coal ash under the influence of hydrostatic pressure generated in a three-axial compression apparatus. The scope of work included determining the compactibility parameters, maximum bulk density and optimal moisture content. Permeability tests were performed for a sample with an average grain composition at three compaction indices IS: 0.964, 0.98 and 1.00. The hydrostatic pressure ranging from 0.5 to 1.8 bar corresponded to the layer depths from 2.17 to 7.83 m. Gradually increasing the pressure during the first loading cycle caused irreversible changes in the structure of the sample by local material agglomeration or grain interlocking. The water permeability coefficient was higher in the second loading cycle than in the first cycle. It was shown that waste coal ash cannot be used as a construction material on its own. To obtain constant filtration properties, the waste coal ash material should be doped, or an optimal compactionshould be used (IS = 1.00). The results presented in this study are important for assessing the use of waste coal ash for construction engineering purposes.
Citation: Recycling
PubDate: 2024-03-04
DOI: 10.3390/recycling9020022
Issue No: Vol. 9, No. 2 (2024)
- Recycling, Vol. 9, Pages 23: A Comprehensive Performance Evaluation of
GGBS-Based Geopolymer Concrete Activated by a Rice Husk Ash-Synthesised
Sodium Silicate Solution and Sodium Hydroxide
Authors: Jonathan Oti, Blessing O. Adeleke, Prageeth R. Mudiyanselage, John Kinuthia
First page: 23
Abstract: Commercial sodium hydroxide (NaOH) and sodium silicate (SS) are commonly used as alkaline activators in geopolymer concrete production despite concerns about their availability and associated CO2 emissions. This study employs an alternative alkaline activator (AA) synthesized from a sodium silicate alternative (SSA) solution derived from rice husk ash (RHA) and a 10 M sodium hydroxide solution. The initial phase established an optimal water-to-binder (W/B) ratio of 0.50, balancing workability and structural performance. Subsequent investigations explored the influence of the alkali/precursor (A/P) ratio on geopolymer concrete properties. A control mix uses ordinary Portland cement (OPC), while ground granulated blast-furnace slag (GGBS)-based geopolymer concrete—GPC mixes (GPC1, GPC2, GPC3, GPC4) vary the A/P ratios (0.2, 0.4, 0.6, 0.8) with a 1:1 ratio of sodium silicate to sodium hydroxide (SS: SH). The engineering performance was evaluated through a slump test, and unconfined compressive strength (UCS) and tensile splitting (TS) tests in accordance with the appropriate standards. The geopolymer mixes, excluding GPC3, offer suitable workability; UCS and TS, though lower than the control mix, peak at an A/P ratio of 0.4. Despite lower mechanical strength than OPC, geopolymers’ environmental benefits make them a valuable alternative. GPC2, with a 0.4 A/P ratio and 0.5 W/B (water to binder) ratio, is recommended for balanced workability and structural performance. Future research should focus on enhancing the mechanical properties of geopolymer concrete for sustainable, high-performance mixtures.
Citation: Recycling
PubDate: 2024-03-14
DOI: 10.3390/recycling9020023
Issue No: Vol. 9, No. 2 (2024)
- Recycling, Vol. 9, Pages 24: A Framework for Developing a National
Research Strategy for Water Reuse
Authors: Arkalgud Ramaprasad, Thant Syn
First page: 24
Abstract: Water reuse is critical to national development, sustenance, and survival in this era of climate, demographic, and social changes. There is no systemic national approach to systematically addressing this challenge. This paper presents a framework and method to develop a national research strategy for water reuse. It presents an ontology of water reuse strategies that encapsulates the combinatorial complexity of the problem clearly, concisely, and comprehensively. Subsequently, it discusses the method to use the framework to develop a national strategy, adapt it through feedback and learning, and ultimately effect a revolutionary change in the strategy for water reuse.
Citation: Recycling
PubDate: 2024-03-16
DOI: 10.3390/recycling9020024
Issue No: Vol. 9, No. 2 (2024)
- Recycling, Vol. 9, Pages 25: Unlocking the Potential of Agrifood Waste for
Sustainable Innovation in Agriculture
Authors: Monica Voss, Carlotta Valle, Emanuela Calcio Gaudino, Silvia Tabasso, Claudio Forte, Giancarlo Cravotto
First page: 25
Abstract: The United Nations Environment Programme’s (UNEP’s) Food Waste Index Report 2021 highlights a global annual food waste of 1 billion tons. The UNEP plays a crucial role in achieving Sustainable Development Goal (SDG) 12.3, which aims to halve per capita global food waste (FW) at the retail and consumer levels and reduce food losses along production and supply chains globally by 2030. On the other hand, the agricultural sector faces the challenge of increasing productivity to feed the world’s growing population while reducing the environmental impact on ecosystems and human health. In this context, the conversion of agri-food waste (AFW) into biocides, bio-based fertilizers (BBFs) and biostimulants could represent a successful approach to tackle all these issues. This review shows the latest findings on the different sources of AFW and the application of their bioactive compounds in agriculture. Increasing crop yields and improving plant physiology through the utilization of AFW-derived value products aligns with a circular economy approach, bolstering people’s confidence in managing food waste for improved food production.
Citation: Recycling
PubDate: 2024-03-20
DOI: 10.3390/recycling9020025
Issue No: Vol. 9, No. 2 (2024)
- Recycling, Vol. 9, Pages 26: Non-Structural Vibro-Compressed Concrete
Incorporating Industrial Wastes
Authors: Gabriela Bertazzi Pignotti, Ana Mafalda Matos, Fernanda Giannotti da Silva Ferreira
First page: 26
Abstract: This study presents more eco-efficient concrete formulations for precast vibro-compressed masonry blocks. The proposed formulations incorporated industrial waste, glass powder (GP), and quartz powder (QP), in which natural aggregate was partially replaced by QP (10%) and Portland cement by GP (10% and 20%). The best combination of powder materials, water, and admixture was optimised at mortar level, considering a “zero slump” criteria and compressive strength. Afterwards, studies at concrete level followed. Specimens were vibrated and compressed in laboratory and immediately demoulded, aiming to simulate the industrial process. The compressive strength decreased when GP and QP were used alone; however, when combining 10% GP as cement replacement + 10% QP as fine aggregate replacement, the compressive strength increased by approximately 26.6% compared to the reference concrete. Water absorption results varied between 8.92 and 17.9%, and the lowest absorption was obtained by concrete specimens incorporating 20% GP. The UPV presented a narrow range of variation among all concrete mixtures under study, around 2–2.5 km/s at 28 days, whereas electrical resistivity was achieved at 28 days, at 20,000 and 25,000 ohms. Although there were some limitations of the casting process at the laboratory scale, the research results showed promising results, and it seems feasible to use this waste as a substitute for non-renewable raw materials in the production of concrete on an industrial scale. This can provide added value to abundant local wastes while contributing to a circular concrete economy.
Citation: Recycling
PubDate: 2024-03-25
DOI: 10.3390/recycling9020026
Issue No: Vol. 9, No. 2 (2024)
- Recycling, Vol. 9, Pages 27: Blue Circular Economy—Reuse and
Valorization of Bivalve Shells: The Case of Algarve, Portugal
Authors: Fernanda Caroline Magalhães, Poliana Bellei, Inês Flores-Colen, Eduarda Marques da Costa
First page: 27
Abstract: The Circular Economy emerges as an alternative to reinvent the linear production model (take–make–waste), focusing on reintegrating waste into the production cycle, and aiming to minimize both environmental disposal and the unrestrained extraction of raw materials. In this context, the concept of Blue Economy arises, an approach centered on preserving and valorizing marine and coastal resources. This article aims to develop a model for the circuit of bivalve shells, emphasizing the transformation of the residues into new products and identifying how these processes affect sociocultural, economic, and environmental dimensions. The methodology involved the surveying of local stakeholders directly involved in bivalve production and consumption to identify the relationship of these stakeholders with the production, marketing, and disposal of bivalves. It is concluded that biowaste has potential, and there is interest among local stakeholders in reusing it, but a lack of knowledge and connection among stakeholders ultimately leads to the devaluation of the product. The circuit of bivalves is necessary to identify value, propose correct collection, and stimulate interest in their reuse, both by other industries and by the aquaculture industry itself. Exploring the potential for reusing bivalves and mitigating their waste, as well as preventing improper disposal, could drive the development of the Blue Circular Economy in coastal regions.
Citation: Recycling
PubDate: 2024-03-30
DOI: 10.3390/recycling9020027
Issue No: Vol. 9, No. 2 (2024)
- Recycling, Vol. 9, Pages 28: A Sustainable Solution with Improved Chemical
Resilience Using Repurposed Glass Fibers for Sewage Rehabilitation Pipes
Authors: Devanand Chelot, Shivnarain Ravichandran, Priyank Upadhyaya
First page: 28
Abstract: This paper introduces a sustainable sewage rehabilitation solution, utilizing repurposed glass fibers for enhanced chemical resilience and environmental conservation. The approach involves dividing a unitary pipe into segments, assembled during commissioning, aiming to reduce installation and transportation costs, particularly in less accessible areas. Each pipe segment comprises a multi-layered glass fiber composite sandwich, joined by an adhesive reinforced with recycled glass fibers. The glass fiber-reinforced plastic (GFRP) pipe features a core of blended sand impregnated with resin, an outer layer for impact resistance, and an inner layer to prevent corrosion. Chemical resilience is assessed through a 10,000 h strain corrosion study exposing both unitary and two-piece circular GFRP pipes to sulfuric acid in a deflected condition. An apparent hoop tensile test evaluates mechanical integrity before and after exposure. The experimental results reveal that the two-piece pipe with a tongue and groove joint (TGJ) with recycled glass fiber adhesive exhibits superior long-term bending stress and failure strain % compared to unitary pipes. This enhancement is attributed to the TGJ’s improved load-bearing capability and chemical resistance. The failure strain % of the two-piece pipe (1.697%) is higher compared to the unitary pipe (1.2613%). The long-term bending stress of the two-piece pipe obtained is 119.94 MPa whereas the unitary pipe reaches 93.48 MPa at the 50-year mark. The cost analysis supports the adoption of the two-piece pipe over unitary pipes due to a 40% reduction in carbon emissions and transportation cost. The novelty lies in the utilization of multi-piece pipes with enhanced chemical resilience, achieved through the incorporation of milled fiberglass reinforcements in the TGJ. Strain corrosion tests take a long time to perform; hence, an accelerated test is needed to improve the current recommended testing standard.
Citation: Recycling
PubDate: 2024-03-31
DOI: 10.3390/recycling9020028
Issue No: Vol. 9, No. 2 (2024)
- Recycling, Vol. 9, Pages 29: The Influence of a Commercial Few-Layer
Graphene on the Photodegradation Resistance of a Waste Polyolefins Stream
and Prime Polyolefin Blends
Authors: S. M. Nourin Sultana, Emna Helal, Giovanna Gutiérrez, Eric David, Nima Moghimian, Nicole R. Demarquette
First page: 29
Abstract: This work investigated the photostabilizing role of a commercially available few-layer graphene (FLG) in mixed polyolefins waste stream (MPWS), ensuring extended lifespan for outdoor applications. The investigation was conducted by analyzing carbonyl content increase, surface appearance, and the retention of mechanical properties of UV-exposed MPWS/FLG composites. Despite the likely predegraded condition of MPWS, approximately 60%, 70%, 80%, and 90% of the original ductility was retained in composites containing 1, 4, 7, and 10 wt.% FLG, respectively. Conversely, just 20% of the original ductility was retained in unfilled MPWS. Additionally, less crack density and lower carbonyl concentrations of the composites also highlighted the photoprotection effect of FLG. For prime polyolefin blends, only 0.5 wt.% or 1 wt.% FLG was sufficient to preserve the original surface finishing and protect the mechanical properties from photodegradation. Hence, it was observed that MPWS requires more FLG than prime polyolefin blends to get to comparable property retention. This could be attributed to the poor dispersion of FLG in MPWS and inevitable uncertainties such as the presence of impurities, pre-degradation, and polydispersity associated with MPWS. This study outlines a potential approach to revalorize MPWS that possess a minimal intrinsic value and would otherwise be destined for landfill disposal.
Citation: Recycling
PubDate: 2024-04-09
DOI: 10.3390/recycling9020029
Issue No: Vol. 9, No. 2 (2024)
- Recycling, Vol. 9, Pages 30: An Overview of the Current Trends in Marine
Plastic Litter Management for a Sustainable Development
Authors: Maria Râpă, Elfrida M. Cârstea, Anca A. Șăulean, Cristina L. Popa, Ecaterina Matei, Andra M. Predescu, Cristian Predescu, Simona I. Donțu, Alexandra G. Dincă
First page: 30
Abstract: This review summarizes recent data related to the management of marine plastic litter to promote sustainable development. It discusses the distribution and identification of marine plastic litter, assesses the potential socio-economic and environmental impacts of these pollutants, and explores their recovery strategies, from a circular economy perspective. The main findings indicate that the majority of marine plastic litter originates from land-based sources. Current technologies and approaches for valorizing marine plastic litter include mechanical and chemical recycling, blockchain technologies by providing traceability, verification, efficiency and transparency throughout the recycling process, and public awareness programs and education. The developed policies to prevent marine plastic litter emphasize regulations and initiatives focused toward reducing plastic use and improving plastic waste management. By adopting a holistic and sustainable approach, it is possible to mitigate the environmental impact of marine plastic debris while simultaneously creating economic opportunities.
Citation: Recycling
PubDate: 2024-04-09
DOI: 10.3390/recycling9020030
Issue No: Vol. 9, No. 2 (2024)
- Recycling, Vol. 9, Pages 31: Rural Urban Nutrient Partnership (RUN): Life
Cycle Assessment of Multi Nutrient Recovery from Kitchen Waste and
Blackwater
Authors: Heinz Stichnothe, Ben Joseph, Volker Preyl, Carsten Meyer
First page: 31
Abstract: Newly developed and innovative RUN technology aims to recover nutrients from urban wastewater (blackwater) and biowaste (kitchen waste). The development of RUN technology has been supported by the life cycle assessment (LCA) in order to identify hotspots and trade-offs. While the performance of the process at a laboratory scale did not show any environmental benefits from P recovery, the LCA results have helped to improve the environmental performance at the following scale-up step. The recovery of P on a technical scale was environmentally beneficial, especially in terms of the global warming potential (GWP). However, there were still some trade-offs, e.g., freshwater and marine eutrophication were slightly higher compared to conventional P fertilizer production. Given that P is considered a critical raw material and that climate change is probably the most pressing environmental issue, RUN technology has the potential to deliver on both domains.
Citation: Recycling
PubDate: 2024-04-17
DOI: 10.3390/recycling9020031
Issue No: Vol. 9, No. 2 (2024)
- Recycling, Vol. 9, Pages 3: Improvement of Thermal Protection in Recycled
Polyolefins through Hybrid Mesoporous Silica–Antioxidant Particles
Authors: Enrique Blázquez-Blázquez, Rosa Barranco-García, Tamara M. Díez-Rodríguez, Pilar Posadas, Ernesto Pérez, María L. Cerrada
First page: 3
Abstract: The deficient management of plastic waste has caused a serious worldwide environmental problem. Thus, one of the main challenges for the industry in the plastics sector in contributing to sustainability and a circular economy consists of providing a subsequent service life to this waste. For that purpose, the appropriate incorporation of antioxidants will play a key role in preventing or postponing the degradation of plastic waste, where the formation of radicals is initiated during its previous lifetime by the action of degrading agents. Functionalized particles, based on mesoporous MCM-41 silica with Irganox 1076, were prepared with two different protocols and were further incorporated into a material containing virgin PP and 30 wt.% of recycled PP, with the purpose of guaranteeing thermal stability during its next service life. A very significant increase in the thermal stability of the resulting composites was found, attributable to the synergistic action between the Irganox 1076 antioxidant and the MCM-41 particles. In addition, the presence of hybrid particles leads to an important nucleating effect for the crystallization of PP. Moreover, a reinforcing role was also played by these modified mesoporous silicas in the resultant systems. The presented methodology constitutes, therefore, a promising strategy for contributing to the circular economy—since the synergy between the Irganox 1076 antioxidant and MCM-41 particles was found to play an important role in the ultimate performance of recycled polyolefins.
Citation: Recycling
PubDate: 2024-01-02
DOI: 10.3390/recycling9010003
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 4: The Potential Material Flow of WEEE in a
Data-Constrained Environment—The Case of Jordan
Authors: Laila A. Al-Khatib, Feras Y. Fraige
First page: 4
Abstract: The rising concerns about electric and electronic equipment waste (WEEE) come from the rapid increase in demand for appliances and the decreasing lifetimes of equipment. Setting a sustainable WEEE management system that exploits this secondary resource is paramount to maximize resource efficiency, mitigate its environmental impact, and stimulate the circular economy. This paper aims, for the first time, to quantify the material flow expected from recycling the generated WEEE, propose the number of plants required to recycle this secondary resource, and outline the expected economic and environmental benefits that could be achieved from recycling operations. The findings of material flow calculations show that the amount of steel, copper, and aluminum is predominant in the WEEE composition. Also, the expected metal content in WEEE in 2022 is approximately 26 kt, 3.3 kt, and 2.5 kt, respectively. These are expected to substantially increase to approximately 109 kt, 11.9 kt, and 9 kt for the three metals in 2050, respectively. Other valuable metals are doubling their quantities between 2022 and 2050 to reach approximately 1133 kg silver and 475 kg gold. Approximately, four treatment plants are required to recover these materials in 2030 with relative installation costs of USD 100 million. The forecasted financial revenues of recovering materials included in WEEE and indicators for environmental impact based on life cycle assessment (LCA) are calculated. The results of this study can serve as a preliminary reference for future usage in guiding effective planning for WEEE recycling and sustainable management in the country.
Citation: Recycling
PubDate: 2024-01-09
DOI: 10.3390/recycling9010004
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 5: Degradation of Plastic Materials through
Small-Scale Pyrolysis: Characterization of the Obtained Hydrocarbons and
Life Cycle Analysis
Authors: José Alfredo Torres Tovar, Hermelinda Servín-Campuzano, Mauricio González-Avilés, Hugo Sobral, Francisco Javier Sánchez-Ruiz
First page: 5
Abstract: Plastic waste signifies a global predicament, aggravated by deficient management practices. Unearthing methods to repurpose energy from this waste is pivotal. This study delves into the pyrolytic degradation of low-density plastics to convert plastic waste into valuable products on a modest scale. A small-scale, low-CO2 emitting distiller was employed in the process. A zeolite was harnessed as a catalyst to augment the temperature and hasten the pyrolysis process. A comprehensive life cycle analysis was executed to assess the environmental impact of the process. In this scenario, zeolite-facilitated pyrolysis was more proficient compared to traditional thermal pyrolysis, generating a yield of 22.5% with the catalyst, contrasting with 18% without. A kinetic model was formulated, observing reaction mechanisms and temperature escalation and culminating in the extraction of aromatic oils. These oils were further distilled to produce liquid hydrocarbons, beginning the distillation at 60 °C with the catalyst. Characterization of the secured hydrocarbons was conducted using infrared, Raman spectroscopy, and gas chromatography, discovering compounds akin to gasoline, such as benzene, toluene, and xylenes. Additionally, the procedure exhibited a minimal environmental detriment, as validated by the life cycle analysis. This study concludes by highlighting the potential of small-scale, low-CO2 emitting pyrolytic degradation of low-density plastics for energy recovery from plastic waste, demonstrating the practical and environmental benefits of this avant-garde method.
Citation: Recycling
PubDate: 2024-01-15
DOI: 10.3390/recycling9010005
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 6: Two-Step Bio-Dissolution of Metals from
Printed Circuit Boards Using Acidophilic Iron- and Sulfur-Oxidizing
Mesophiles
Authors: Kundani Magoda, Philiswa N. Nomngongo, Lukhanyo Mekuto
First page: 6
Abstract: To date, electronic waste (e-waste) is the fastest-growing waste stream worldwide due to technological advancement and the advent of the Fourth Industrial Revolution. Although e-waste is an environmental hazard, these materials are considered good secondary sources of metals. This study examined the bioleaching of metals from printed circuit boards, where a two-step bioleaching approach was used with iron–sulfur-oxidizing microorganisms at different e-waste particle sizes. The metal analysis from the different particle sizes (PSs) showed that copper (Cu), tin (Sn), and lead (Pb) were predominantly deposited in the coarser fraction, ranging from 500 to 710 µm at 28.7, 20.5, and 11.1 wt.%, respectively. On the other hand, metals such as iron (Fe), zinc (Zn), manganese (Mn), nickel (Ni), and aluminum (Al) were mostly deposited in the finer fraction, which ranged from 38 to 150 µm at 37.3, 5.9, 8.8, 1.3, and 4.2 wt.%, respectively. After the bioleaching process, it was observed that higher metal extraction occurred at a PS ranging from 38 to 150 µm, which achieved recovery efficiency rates of 62.9%, 68.2%, 95.3%, 86.1%, 61.9%, 47.2%, 21.2%, and 63.6% for Al, Cu, Fe, Mn, Ni, Pb, Sn, and Zn, respectively, over 10 days.
Citation: Recycling
PubDate: 2024-01-18
DOI: 10.3390/recycling9010006
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 7: Hygrothermal Optimization for Excavated Soil
Reuse in Various Climate Buildings: A Global Literature Meta-Analysis
Authors: Yannick Igor Fogue Djombou, Melvyn Gorra, Bruno Malet-Damour
First page: 7
Abstract: This article investigates the hygrothermal properties of earth-based materials by analyzing experimental data from 88 articles spanning 32 countries worldwide. The focus is determining effective techniques for leveraging the use of excavated soil in construction, particularly emphasizing enhancement of hygrothermal comfort in specific climates. Based on statistical analysis, the study presents a comprehensive classification of earth production techniques, incorporating additives, and examines their impacts on hygrothermal properties of excavated soils. Additionally, it explores the intricate relationship between the climatic conditions of a region and the chosen earth-material production techniques. The analysis aims to propose standard parameters for earthen materials and identify gaps in both methods and experimental studies. Therefore, this study will provide valuable insights by proposing new design tools (ternary diagrams) to maximize the use of excavated soils in construction practices. The proposed diagrams illustrate the intricate relation linking either hygrothermal properties, the climate zone, and manufacturing techniques, or the relation between the most studied manufacturing techniques (compaction, fibered, and stabilization) and expected dry thermal conductivity. Thereby, results from this meta-analysis and critical review will contribute to advancing sustainable construction practices.
Citation: Recycling
PubDate: 2024-01-22
DOI: 10.3390/recycling9010007
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 8: Evolution, Prospects, and Predicaments of
Polymers in Marine Applications: A Potential Successor to Traditional
Materials
Authors: Aravind Dhandapani, Senthilkumar Krishnasamy, Senthil Muthu Kumar Thiagamani, Diwahar Periasamy, Chandrasekar Muthukumar, Thirumalai Kumaran Sundaresan, Saood Ali, Rendi Kurniawan
First page: 8
Abstract: Polymers are ideal solutions for architects and constructors in the marine field who require materials that can achieve light and stable structures owing to their unique advantages. For instance, they possess a high strength-to-weight ratio, high wear resistance and fatigue strength, resistance to corrosion, ease of fabrication, and superior vibration damping behavior. These properties make polymers well suited for marine-based applications. However, polymers have their disadvantages, such as contributing to plastic pollution, which has a detrimental impact on the environment. In recent times, various concurrent methods have been employed to advance the future of polymers. This review explores (i) an overall view of polymers used in marine industries, (ii) a focus on reducing plastic wastage, (iii) challenges involved in recycling polymers and ensuring their sustainability, and (iv) the development of renewable plastics.
Citation: Recycling
PubDate: 2024-01-22
DOI: 10.3390/recycling9010008
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 9: A Comprehensive Review of Lithium-Ion Battery
(LiB) Recycling Technologies and Industrial Market Trend Insights
Authors: Bowen He, Han Zheng, Karl Tang, Ping Xi, Muqing Li, Laiwei Wei, Qun Guan
First page: 9
Abstract: Adopting EVs has been widely recognized as an efficient way to alleviate future climate change. Nonetheless, the large number of spent LiBs associated with EVs is becoming a huge concern from both environmental and energy perspectives. This review summarizes the three most popular LiB recycling technologies, the current LiB recycling market trend, and global recycling magnates’ industrial dynamics regarding this subject. We mainly focus on reviewing hydrometallurgical and direct recycling technologies to discuss the advancement of those recycling technologies and their future commercialization pathway.
Citation: Recycling
PubDate: 2024-01-26
DOI: 10.3390/recycling9010009
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 10: Evaluation of the Landfill Storage Capacity
in Slovakia, Compared to the EU Situation
Authors: Zuzana Šimková, Marcela Taušová, Katarína Čulková, Peter Tauš, Danylo Shyp, David Krasniči, Simona Novotná
First page: 10
Abstract: The circular economy and efficient use of resources gained importance in the context of sustainable development. The paper aims to evaluate the development of landfilling in Slovakia. The next goal is to assess the trend in compared with the EU’s situation. The presented research presents a continuation of previous research in the area of waste recycling in Slovakia, pointing to the waste and landfilling, which is deserving of analysis from a long-term perspective. The research is carried out via data collection at the EU level by recording continuously published values. The paper’s results are processed in statistical software. Considering regional development, landfilling in Slovakia is followed up according to the geographical units of the entire country. The results shown here show that a higher recycling capacity is required and Slovakia should decrease its level of landfill. Such results can be used in the waste treatment area, protection of the living environment and sustainable development of regions.
Citation: Recycling
PubDate: 2024-01-27
DOI: 10.3390/recycling9010010
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 11: Carbon Fiber Composites Recycling Technology
Enabled by the TuFF Technology
Authors: Tekin Ozdemir, Joseph M. Deitzel, Roger Crane, Shridhar Yarlagadda, Chris Blackwell, Mark Davis, Rebecca Emmerich, Dirk Heider
First page: 11
Abstract: Carbon Fiber Composites (CFCs) recycling has received increasing interest by the composites industry, but it is still in its early stages as an industry. There are two primary challenges that need to be addressed in order to achieve full property retention during CFC recycling: (1) the ability to recover the fiber content without property loss; and (2) conversion of the recycled, short fiber material back into high-performance CFC structures. The ability to manufacture high fiber volume fraction CFCs with end-of-life products would provide an opportunity to reduce material cost and lifetime-embodied energy. In this paper, recycled, short carbon fibers are processed via solvolysis and converted into high-performance CFCs with fiber volume fraction of ~50% and excellent composite property retention. This is enabled through alignment of the discontinuous, recycled fiber feedstock using the Tailorable universal Feedstock for Forming (TuFF) process. The paper introduces the necessary steps to process the fibers in the wet-laid process and explores the resulting mechanical and microstructural properties. The importance of incoming fiber surface quality and the effect of surface contamination from residue left by the recycling process on both the TuFF process and final composite properties is discussed in detail. A pyrolytic process has been adopted to remove the residue that is a by-product of the recycling process from the incoming recycled fiber surface. The approach presents a promising pathway for the recycling of high-performance CFCs.
Citation: Recycling
PubDate: 2024-02-02
DOI: 10.3390/recycling9010011
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 12: Using Cassava Starch Processing By-Product
for Bioproduction of 1-Hydroxyphenazine: A Novel Fungicide against
Fusarium oxysporum
Authors: Tu Quy Phan, San-Lang Wang, Thi Hanh Nguyen, Thi Huyen Nguyen, Thi Huyen Thoa Pham, Manh Dung Doan, Thi Ha Trang Tran, Van Anh Ngo, Anh Dzung Nguyen, Van Bon Nguyen
First page: 12
Abstract: This study aimed to develop the eco-friendly production of bioactive 1-hydroxyphenazine (HP) through fermentation using an industrial processing by-product of cassava as the main carbon/nitrogen source. Cassava starch processing by-product (CSPB) was screened as a suitable substrate for fermentation to produce HP with a high yield. Mixing CSPB with a minor amount of tryptic soy broth (TSB) at a ratio of 8/2 and with 0.05% K2HPO4 and 0.05% FeSO4 was effective in HP production by Pseudomonas aeruginosa TUN03. HP was also further scaled up through production on a bioreactor system, which achieved a higher level yield (36.5 µg/mL) in a shorter fermentation time (10 h) compared to its production in the flask (20.23 µg/mL after 3 days). In anti-fungal activity tests against various Fusarium phytopathogens, HP exhibited the most significant effect on Fusarium oxysporum F10. It could inhibit the mycelial growth of this fungus, with an inhibition rate of 68.7% and anti-spore germination activity of up to 98.4%. The results of the docking study indicate that HP effectively interacted with the protein 1TRY targeting anti-F. oxysporum, with all obtained docking parameters in the accepted range. This study supports the novel use of CSPB as the carbon/nitrogen source for P. aeruginosa fermentation to produce HP, a F. oxysporum anti-fungal agent reported here for the first time.
Citation: Recycling
PubDate: 2024-02-02
DOI: 10.3390/recycling9010012
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 13: Battery Waste Management in Europe: Black
Mass Hazardousness and Recycling Strategies in the Light of an Evolving
Competitive Regulation
Authors: Mattia Gianvincenzi, Enrico Maria Mosconi, Marco Marconi, Francesco Tola
First page: 13
Abstract: The increasing significance of batteries in the 21st century and the challenges posed by the anticipated surge in end-of-life batteries, particularly within the European context, are examined in this study. Forecasts predict a notable escalation in battery waste, necessitating a focus on the recycling of black mass (BM)—a complex and hazardous byproduct of the battery recycling process. Employing systematic analysis, this research investigates the hazardous nature of BM derived from various battery types. The study underscores the urgent need for definitive legislative classification of BM’s hazardous properties (HPs), in accordance with European regulations. This comprehensive examination of BM’s HPs contributes significantly to the understanding of BM recycling complexities, proving essential for industry stakeholders and guiding future developments in this field. Additionally, the study explores innovative technologies and strategies that could improve recycling efficiency and reduce associated risks. A pivotal finding of this investigation is the inherently hazardous nature of BM, leading to the recommendation that BM should be classified at a minimum under the “HP3—Flammable” category. This discovery underscores the critical need for stringent management protocols and robust regulatory frameworks to address the burgeoning challenge of battery waste in Europe.
Citation: Recycling
PubDate: 2024-02-04
DOI: 10.3390/recycling9010013
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 14: Effect of Surface Condition on the Results of
Chemical Composition Measurements of Scrap Copper Alloys
Authors: Łukasz Bernat, Tomasz Jurtsch, Grzegorz Moryson, Jan Moryson, Grzegorz Wiczyński
First page: 14
Abstract: The processing of copper-bearing scrap makes it possible to reduce the costs and energy consumption of obtaining copper alloy products compared to producing them from primary raw materials. To achieve this, it is necessary to quickly and accurately determine the content of alloying elements in individual scrap elements. However, the copper-bearing scrap obtained at secondary raw materials collection points consists of elements with various surface conditions (due to contamination, shape, paint coatings, roughness, etc.). The paper contains research results on the influence of surface roughness and paint coatings on the measurement result of the content of alloying elements in copper-bearing scrap. Three mobile spectrometers were used for measurements: spark-induced optical emission spectroscopy (OES), X-ray fluorescence spectrometry (XRF) and laser-induced breakdown spectroscopy (LIBS). The tests used elements with different surface roughness (from Ra = 0.03 μm to 6.7 μm) and covered with various types of varnish (alkyd, water-based, oil-phthalic, acrylic, oil-alkyd). It was found that the roughness of Ra < 2 μm does not significantly affect the results of the measurements with the OES and LIBS spectrometers, and a larger scatter of measurement results was observed for the XRF spectrometer compared to OES and LIBS. For Ra > 2 μm, a significant impact of roughness was found on the measurement results (this may result in the erroneous classification of the scrap as an incorrect material group). The influence of paint coatings on the measurement is much stronger compared to surface roughness. Even a single layer of paint can cause a change in the measurement result of the content of alloying elements by more than 10%. In the case of an OES spectrometer, paint coatings may prevent the measurement from being performed (which means that no measurement result can be acquired).
Citation: Recycling
PubDate: 2024-02-04
DOI: 10.3390/recycling9010014
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 15: Optimization of Pyrolysis Process Parameters
for Fuel Oil Production from the Thermal Recycling of Waste Polypropylene
Grocery Bags Using the Box–Behnken Design
Authors: Balasubramaniam Prabha, Desikan Ramesh, Srinivasan Sriramajayam, Doraiswamy Uma
First page: 15
Abstract: The impact of dumping plastic waste is realized in different ecosystems of the planet. Several methods have been adopted to dispose of these wastes for energy recovery. This study, for the first time, proposed the Box–Behnken design technique to optimize the pyrolysis process parameters for fuel oil production from waste polypropylene (PP) grocery bags using a semibatch-type pyrolytic reactor. The semibatch-type pyrolytic reactor was developed and employed to produce fuel oil from waste PP grocery bags. The effect of different process parameters on fuel oil production was comprehensively analyzed using the response surface methodology (RSM) with the conjunction of the Box–Behnken design (BBD). The BBD facilitates the prediction of the response variables with respect to changes in the input variables by developing a response model. The BBD was used to optimize the process parameters, such as the reaction temperature (400–550 °C), nitrogen flow rate (5–20 mL min−1), and substrate feed rate (0.25–1.5 kg h−1), and their effect on the responses were observed. The optimum response yields of the fuel oil (89.34 %), solid residue (2.74%), and gas yield (7.92%) were obtained with an optimized temperature (481 °C), a nitrogen flow rate (13 mL min−1), and a feed rate (0.61 kg h−1). The quadratic model obtained for the fuel oil response denotes the greater R2 value (0.99). The specific gravity and calorific value of the fuel oil were found to be 0.787 and 45.42 MJ kg−1, respectively. The fuel oil had higher research octane number (RON) (100.0 min) and motor octane number (MON) (85.1 min) values. These characteristics of the fuel oil were matched with conventional petroleum fuels. Further, Fourier transform infrared spectroscopy (FT-IR) and gas chromatography–mass spectroscopy (GC-MS) were used to analyze the fuel oil, and the results revealed that the fuel oil was enriched with different hydrocarbons, namely, alkane (paraffins) and alkene (olefins), in the carbon range of C4–C20. These results, and also the fractional distillation of the fuel oil, show the presence of petroleum-range hydrocarbons in the waste PP fuel oil.
Citation: Recycling
PubDate: 2024-02-06
DOI: 10.3390/recycling9010015
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 16: Geopolymerization of Recycled Glass Waste: A
Sustainable Solution for a Lightweight and Fire-Resistant Material
Authors: Marios Valanides, Konstantinos Aivaliotis, Konstantina Oikonomopoulou, Alexandros Fikardos, Pericles Savva, Konstantinos Sakkas, Demetris Nicolaides
First page: 16
Abstract: Glass is considered a sustainable material with achievable recovery rates within the EU. However, there are limited data available for construction glass waste management. Furthermore, glass is a heavy material, and considering the geographical limitations of Cyprus, the transportation trading cost within the EU is extremely high. Therefore, another method for utilizing this by-product should be developed. The aim of this research is to investigate the production of a low-cost, lightweight and fireproof material able to retain its structural integrity, using the geopolymerization method with the incorporation of randomly collected construction glass waste. The glass waste was initially processed in a Los Angeles abrasion machine and then through a Micro-Deval apparatus in order to be converted to a fine powder. Mechanical (compressive and flexural strength), physical (setting time and water absorption) and thermal properties (thermal conductivity) were investigated. The fire-resistant materials presented densities averaging 450 kg/m3 with a range of compressive strengths of 0.5 to 3 MPa. Additionally, a techno-economic analysis was conducted to evaluate the viability of the adopted material. Based on the results, the final geopolymer product has the potential to be utilized as a fire resistance material, preventing yielding or spalling.
Citation: Recycling
PubDate: 2024-02-07
DOI: 10.3390/recycling9010016
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 17: A Critical Review on the Application of
Recycled Carbon Fiber to Concrete and Cement Composites
Authors: Manan Bhandari, Il-Woo Nam
First page: 17
Abstract: Carbon fiber (CF) exhibit extraordinary properties, such as high specific and tensile strength, high elastic modulus, light weight, and weather resistance, which has led to a rapid increase in the use of CF in sectors such as aerospace, sports equipment, energy storage, automotive, construction, and wind energy applications. However, the increase in CF applications has led to a massive production of CF waste. As CF is non-biodegradable, it results in CF accumulation in landfills. CF waste is a rapidly growing ecological hazard because of its high energy consumption and expensive production methods. The properties of carbon fibers can be preserved even after recycling given the development of recycling technology; therefore, multiple studies have been conducted to demonstrate the effect of recycled carbon fiber (RCF) in different composites such as cement-based composites. This review presents the results of studies conducted on the application of RCF to cement composites and analyzes those results to investigate the effect of RCF on the properties of cement composites such as mechanical properties (compressive strength, flexural strength, and tensile strength), fracture characteristics (fracture toughness and fracture energy), electrical properties, and workability. Overall, the studies demonstrated a positive trend in the application of RCF to cement composites.
Citation: Recycling
PubDate: 2024-02-07
DOI: 10.3390/recycling9010017
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 18: Performance of the Food Waste Recycling Law
in Japan with Reference to SDG 12.3
Authors: Tomoko Okayama, Kohei Watanabe
First page: 18
Abstract: SDG target 12.3 calls for halving food waste in retail, food service, and households by 2030. The food waste index developed for this purpose includes parts attached to food that are usually removed intentionally (“unavoidable food waste”) and counts conversion into animal feed and utilisation as biomaterial as a means of reduction. In Japan, the “Food Waste Recycling Law”, which has been in effect since 2001, promotes the recycling of food waste generated from businesses, designating feed conversion as a top priority. On the other hand, based on the more recent “Food Loss Reduction Promotion Act” of 2019, the government is currently promoting reduction in avoidable food waste to meet the SDG target. Based on statistical sources and interviews with ministry officers, this paper explains the history and achievements of Japan’s 23-year policy based on the Food Recycling Law, as well as the tension between the two legislations.
Citation: Recycling
PubDate: 2024-02-08
DOI: 10.3390/recycling9010018
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 19: Drivers and Barriers in the Production and
Utilization of Second-Generation Bioethanol in India
Authors: Falguni Pattnaik, Biswa R. Patra, Sonil Nanda, Mahendra K. Mohanty, Ajay K. Dalai, Jaya Rawat
First page: 19
Abstract: Second-generation biorefinery refers to the production of different types of biofuels, biomaterials, and biochemicals by using agri-based and other lignocellulosic biomasses as substrates, which do not compete with arable lands, water for irrigation, and food supply. From the perspective of transportation fuels, second-generation bioethanol plays a crucial role in minimizing the dependency on fossil-based fuels, especially gasoline. Significant efforts have been invested in the research and development of second-generation bioethanol for commercialization in both developing and developed countries. However, in different developing countries like India, commercialization of second-generation bioethanol has been obstructed despite the abundance and variety of agricultural feedstocks. This commercial obstruction was majorly attributed to the recalcitrance of the feedstock, by-product management, and marginal subsidies compared to other nations. This article reviews the major roadblocks to the viability and commercialization of second-generation biofuels, especially bioethanol in India and a few other leading developed and developing nations. This article also reviews the biomass availability, technological advancements, investments, policies, and scale-up potential for biorefineries. A thorough discussion is made on the prospects and barriers to research, development, and demonstration as well as strengths, weaknesses, opportunities, and threats for the commercialization of second-generation bioethanol.
Citation: Recycling
PubDate: 2024-02-09
DOI: 10.3390/recycling9010019
Issue No: Vol. 9, No. 1 (2024)
- Recycling, Vol. 9, Pages 20: Analysis of Essential Features and Optimal
Operational Parameters of an RF-ICP Torch for Waste Treatment Applications
Authors: Mustafa A. Aldeeb, Sharif Abu Darda, Vahid Damideh, Isaac Hassen, Hossam A. Gabbar
First page: 20
Abstract: Recently, plasma-based pyrolysis has gained increasing prominence as a technology in response to the growing challenges in waste disposal and the recognition of opportunities to generate valuable by-products. The efficiency of the pyrolysis process is intricately tied to the characteristics of the plasma involved, particularly the effective electron temperature (Teff) and plasma density (ne). This study aimed to conduct a comprehensive examination of the essential features and optimal operational parameters of a developed RF-ICP torch specifically designed for small-scale municipal solid waste (MSW) pyrolysis (mixture of paper and polypropylene) with the goal of controlling both the torch and the overall process. Using optical emission spectroscopy (OES), we measured plasma parameters, specifically (Teff) and (ne), while varying argon gas flow rates and RF powers. The (Teff) and (ne)were determined using the Boltzmann plot and Stark broadening, respectively. The RF torch was found to generate (ne) up to approximately 2.8×1020 cm−3 and (Teff) up to around 8200 K, with both parameters being controlled by the discharge power and gas flow rate. Additionally, a power-losing mechanism, namely the anomalous skin effect, was detected during the study, which is uncommon in atmospheric plasma discharge.
Citation: Recycling
PubDate: 2024-02-15
DOI: 10.3390/recycling9010020
Issue No: Vol. 9, No. 1 (2024)
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