Recycling — Open Access Journal

In this work, recycling of post-consumer carpets into structural composites using a modified vacuum assisted resin transfer molding process has been demonstrated. Fabrication of carpet composites addressed the problem related to the environmental effect of waste carpet. Application of the recycled carpet composite as the noise barrier structure has been studied in terms of noise absorption coefficient. Results show that the carpet composite absorbs noise better than conventional noise barrier at a wide spectrum of frequency. Effect of weather exposure on the carpet composite showed the degradation in the mechanical properties. Nanoclay films are also used on the carpet composite and show no change in the noise absorption ability. Full article

The main environmental issue associated with compost production is the production of a liquid leachate. Leachate from municipal wastes contains carbon, nitrogen, phosphorus, potassium and trace elements that can be used as nutrients by plants. The advantages of the use of organic wastes such as compost leachate as fertilizers are evident. Their use would reduce the consumption of commercial fertilizers, which need, with their production, high cost and energy. This work aims to determine the physical and chemical properties of a specific leachate with a variable composition, collected from the composting line of a mechanical and biological treatment facility. The goal is to assess if the leachates can be used as a potential source for fertilizers, and thus develop and design a sequence of processes which could effectively convert the leachates to commercial fertilizers according to the requirements of the proposal of regulation of the European Parliament of 2016 for fertilizers. Preliminary results show that the leachate samples qualitatively meet the requirements established for the composition of commercial fertilizers, especially organo-mineral fertilizers. Furthermore, there is no production cost of leachate as a raw material. The results show that the leachate is characterized by manageable concentrations of heavy metals which can be removed by adsorption processes, and it presents suitable amounts of organic carbon after a water removal procedure. However, the establishment of the conditions for suitable conversion processes are still under investigation considering the high composition variability due to factors like storage and environmental conditions. Full article

A successful circular economy can only exist when it relies solely on renewable energy sources. The adoption of resilient business models and the consequent redesign of legislation on all sectors are essential to ensure sustainable economic growth. Wind energy can offer clean and renewable energy with a low environmental impact. Nevertheless, waste in end of life composite materials resulting from wind turbines is a problem that needs to be addressed. Composite materials are commonly used in wind turbines due to their excellent mechanical properties, matched by low weight. Notably, the recycling technologies of such materials is limited. Material flows and estimations of end of life materials are of great importance and will convince stakeholders that markets for recycling composites are viable investments. Full article

Millions of tons of plastics are produced and consumed annually and should be recycled in a sustainable way. The effects of different compatibilizers on the properties of wood-mixed waste polymer composites are studied to promote recycling of plastics and to determine the potential of using waste plastics in composites. The effect of different addition levels and blending of compatibilizers is examined as well. The studied properties are microstructure, tensile and flexural properties, impact strength, and water absorption and thickness swelling in immersion. The results show that the addition of the selected compatibilizers improved the properties of wood-mixed waste polymer composites remarkably—all the studied mechanical properties and moisture resistance were improved by 50% or more. The effects depend strongly on the level of addition and the compatibilizer used. Findings show that compatibilization provides a feasible means to recycle waste plastics as feedstock for wood–plastic composites. Full article

The recycling of scrap is one of the common approaches aiming at reduction of mining-based production of critical metals and mitigation of their supply risk as well as processing-related environmental impact. The number of currently available end-of-life vehicles (ELVs) indicates—significant potential for critical metals recycling, especially niobium (Nb). Therefore, the quantification of environmental impact of niobium recovery starts to be an important issue in assessment of sustainability of large-scale recycling processes. In this paper, we assess energy consumption and greenhouse gas (GHG) emissions in individual stages of niobium supply chain in the automotive industry over the period 2010–2050. The different stages including mining, production and recycling are analyzed using dynamic simulation. The results show the majority of the consumed energy (45% of energy demand in niobium supply chain) is used in the primary production stage. This stage also contributes to 72% of total gas emissions of supply chain over the period 2010–2050. Mining of niobium consumes up to 36% of energy and generates ca. 21% of GHG emissions. While, in recycling stage, the secondary production of niobium requires 19% of supply chain energy and generates 7% of gas emissions. The detailed calculations show that recycling of niobium could save around 133–161 m GJ energy between 2010 and 2050. The recycling would also contribute to the reduction of 44–53 mt CO₂-eq in the same period. It shows around 18% reduction of annual emissions between 2010 and 2050 thanks to reuse of niobium in secondary production rather than primary production. Full article

Placing emphasis on promoting the reduction, reuse, recycling, recovery and repair of waste has been a critical aspect of the sustainable waste management agenda. Considering recycling, an environmentally friendly and sustainable waste management option, monetary rewards are in place for certain recyclable municipal waste materials in Finland. The study investigates consumers’ perception about the role of financial incentives in effecting the recycling of municipal solid waste materials in Finland. The study also considers drivers for recycling municipal solid waste on the basis of behavioural change factors, such as environmental risk, behavioural economics, resource value, economic benefit, convenience, knowledge, legislation and belief. It further determines the association between income-earning consumers and non-income-earning consumers in their perception of financial incentives for recycling. The empirical results from the study confirm that the role of financial incentive is important in accelerating the recycling of municipal solid waste. A weak-to-positive relationship exists between drivers for recycling municipal solid waste and recycling behaviour. There exists no statistically significant difference in the means of the perceived role of financial incentives for recycling in the two groups. The introduction of financial incentives for other recyclable wastes is required in order to boost consumers’ participation in the recycling of municipal solid waste. The need to pay more attention to intrinsic and extrinsic factors, as they affect the participation members of the society in the recycling of municipal solid waste, is paramount. This has become necessary in ensuring sustainable waste management in Finland. Full article

With changing consumption patterns, growing populations and increased urbanisation, developing countries face significant challenges with regards to waste management. Waste plastic is a particularly problematic one, with single-use plastic leaking into the environment, including the marine environment, at an unprecedented rate. Around the world, countries are taking action to minimise these impacts, including banning single-use plastics; changing petroleum-based plastics to alternative bio-benign products such as paper, glass or biodegradable plastics; and improving waste collection systems to ensure that all waste is appropriately collected and reprocessed or safely disposed. However, these “solutions” are often met with resistance, from business, government or civil society, due to the intended and unintended consequences, leaving many questioning the most appropriate solution to reducing the leakage. This paper argues that there is no one single solution to addressing the leakage of plastic into the environment, but that the solution is likely to be a combination of the three approaches, based on local considerations. Full article

This work contributes to waste management from two major perspectives. Firstly, waste generation in a previously not-studied location—Awka municipality—was sampled and characterized. Secondly, the characterization was done with improved accuracy using a new method called zero-intercept first-order polynomial regression. The proposed method arrives at composition values and per capita values through polynomial regression that considers sampled waste generation data and household size as regressors, respectively. There are no constituents when no waste is generated and there is no per capita waste when household size is zero, therefore, zero-intercept was imposed on the proposed linear regression approach. An 820 by 11 data matrix from a ten-day sampling in Awka Municipality was used to illustrate the proposed approach; eighty percent of the data was used for training, while twenty percent was used for testing. The results from the proposed method proved more accurate when compared with traditional averaging techniques. The results established for the study area are equally in consonance with known results for similar Nigerian locations, such as organic (73.2%), plastic (8.0%), and recyclable (20.3%). The calculated specific loose volume, specific compact volume, the loose bulk density, and compact bulk density are 2.0 × 10⁻³ m³/kg, 9.9 × 10⁻⁴ m³/kg, 500.0 kg∙m⁻³, and 1010.2 kg∙m⁻³, respectively. The waste generation rate is 416.9 g/capita/day, the organic waste generation rate is 307.1 g/capita/day, the recyclable waste generation rate is 83.0 g/capita/day, paper and textile waste generation rate is 25.2 g/capita/day, loose waste volume rate is 9.02 × 10⁻¹ dm³/capita/day, and compact waste volume rate is 4.51 × 10⁻¹ dm³/capita/day. The solid waste characters were compared among the three income groups of low, middle, and high income earners and the observed trends are literature compliant with city-specific coloration. City-wide estimations were made based on demography, literature, and the established results that would aid waste management planning. Full article

Enormous amount of scrap is generated on the shopfloor during manufacturing. Energy needed to melt increasing quantities of scrap will be ever increasing, and so will be the loss of metal during melting. Hence, conversion of scrap directly into marketable products by solid state processing methods is economical due to a lower energy requirement and a greater yield compared to the melting route. This makes the process more environmentally friendly. However, not all materials can be recycled in a solid state, with equal ease. One therefore needs to quantitatively assess the recyclability of a given kind of scrap. In the present work, a procedure to assess the recyclability of finely divided ferrous metallic scrap generated on the shopfloor is demonstrated. Recyclability includes material and the process used for recycling. For instance, a given material might be more recyclable using one process compared to the other. In the present study, the potential of powder technology (powder metallurgy (PM) and metal injection molding (MIM) based processes are compared for solid-state conversion of scrap directly into usable products. Grinding sludge collected in the shopfloor was pulverized and used as raw material. Properties of sintered parts were found to be significantly better due to in-situ reduction and densification during sintering. A quantitative measure of recyclability, namely, the Recyclability Index (RI) was defined to compare the manufacturability of different products. Recycled ferrous parts manufactured by PM route are found to have a greater RI (superior recyclability) than those manufactured by the MIM route. Complex reduction and sintering mechanisms in MIM parts, particularly, the kinetics of diffusion and volumetric shrinkage, limit suitability of MIM for recycling. In contrast, few industrial parts were developed and manufactured by conventional PM based approach to demonstrate the suitability of this novel recycling process especially for manufacture of porous parts. Full article

Agricultural products such as cassava produce huge amounts of waste when processed into consumable goods. The waste generated is generally considered to contribute largely to environmental pollution. This study therefore investigates the waste management practice that is adopted by cassava processors in Ogun State, Nigeria. Five local government areas (LGAs) dominant in processing cassava were selected for the study on the basis of spatial location distribution, landmass, and population. The survey involved the use of structured questionnaires administered to cassava processors of the selected LGAs. The Statistical Package for Social Sciences (SPSS) software application and descriptive statistics were used for data analysis. Results of the analysis show that the majority (70%) of the cassava processors are females. Cassava peel constitutes 10% of the waste produced, of which 91% is heaped at refuse dumps in most communities. Results also reveal that 86.3% of cassava residues are used for animal feeds. Other findings show that the peels, when dried, are used as biofuel for cooking and there is a significant potential for biogas production. From the data captured from respondents during the study, most processors are willing to pay for an improved waste management system. The study therefore recommends the proper waste management of cassava waste to minimize environmental pollution. Full article

The recyclability of polystyrene, acrylonitrile butadiene styrene and polyvinylchloride waste and their use as a source for 3D printing were studied. Filaments of about 3 mm in diameter were extruded successfully with a small-size extruder. The processed filaments were tested on a broad range of parameters-melt flow index, glass transition temperature, tensile properties and a pyrolysis scenario were obtained. The measured parameters were compared with parameters of virgin counterparts presented in the literature. In order to estimate the composition of the recycled material, Fourier Transform Infrared and elemental analysis of the samples was done. Full article

The main objective of this research was to provide suitable technical, organizational, financial, legal, and social indicators for solid waste management (SWM) systems, which can be used to diagnose the current situation faced by tourist destinations (TD) in Tunisia. To this end, 33 interviews and field visits to hotels in Tunisia were carried out. Specifically, the study covers tourist municipalities, private companies, and environment and tourism authorities. A characterization analysis and a quantification of the solid waste (SW) generated by hotels were also performed. It was found that hotels generate large amounts of mixed SW, especially during the summer period. It represents, for example, 45.5% of the total SW generated per year in Hammamet, and can reach 54.2% during the summer. The interviews indicated that 83% of the hotels collect mixed waste, which is then sent to landfills. The characterization of the SW shows that hotels generate about 58% organic waste, and a minimum of 36% of recyclable waste could be valorized. From a financial point of view, the results indicated that the collected taxes from hotels do not cover the municipalities’ expenses. The findings of the research reported in this paper can be used as a decision-making support. Full article

In the city of Blantyre, much of the generated municipal waste is biowaste, typically mixed with other waste fractions and disposed at the city’s dumpsite. Energy and nutrients could be recovered; however, with many biowaste options available, choosing what technology to implement is difficult. Selecting Organic Waste Treatment Technology (SOWATT) is a tool that supports decision making for selecting a biowaste treatment option considering social, technical, and environmental aspects. SOWATT was used to evaluate options for Blantyre’s Limbe Market. Anaerobic digestion, black soldier fly processing, slow pyrolysis, in-vessel composting, windrow composting, vermicomposting, and wet-biomass-briquetting were considered as options. The performance of each alternative was assessed based on five objectives by government, NGO, and market-based stakeholders in order to determine the most acceptable option for the greatest number of people: something that is rarely done, or if it is the preferences are not rigorously quantified (e.g., stakeholder workshops) and/or weighted against specific objectives. However, given the novelty of the ranking-solicitation process, some participants struggled with the variety of options presented, and further iterations of SOWATT will address this limitation. Ultimately, vermicomposting scored highest of all alternatives and could best achieve the five objectives as prioritized by the stakeholders when implemented. Full article

A novel re-formative polymer composite manufacturing route has been developed by UK and Qatar-based Universities. This novel process recycles domestic-waste thermoplastic material, without the requirement for intensive filtering or washing operations. The produced polymer can be reinforced with recycled glass fibres, forming a structurally load-bearing composite, which may potentially be suitable for use in applications, including utility poles, railway sleepers, and fencing. Thus, infra-red (IR) analysis showed the presence of polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET) in the commingled material. Differential scanning calorimetry (DSC) was used to determine glass transition temperatures and melting temperatures of each of the associated polymer types. Dynamic mechanical thermal analysis (DMTA) was used to determine the storage and loss modulus of the bulk commingled component. Lastly, flexural and tensile strengths of the re-formative polymer with differing proportions of glass fibre were assessed, giving a range of strengths at each glass fibre proportion for possible compositional variation in the polymer type. The recycled polymer is considered a viable structural material for replacing both wooden and concrete components, generating a polymer recycling route with concomitant environmental benefits. This plastic recycling route therefore offers a solution towards achieving climate change targets with a purposeful end-product component. Full article

The agricultural use of sewage sludge brings benefits to soil and plant crops, but due to the possible presence of contaminating substances and pathogenic organisms it is necessary to follow the criteria for safe use for health and the environment. In Brazil, the Conama 375/06 Resolution established criteria and procedures for agricultural use of sewage sludge and Paraná is one of the few states in the country to use this alternative. This case study presents the management process and the results of the agricultural destination of the sludge in Paraná State, Brazil, from 2007, year in which the resolution came into force, to 2017. The management is carried out in two spheres of action: one in the context of the sludge management units (SMU) and another in the agricultural sphere. The sludge is provided free of charge to farmers, which reduces expenses with fertilizers and soil acidity correctives, resulting in economic and social benefits to the communities where it is used. However, from the year 2011 there was a reduction in the amount destined for agricultural use. The requirements of the national regulation make the process complex, overly bureaucratic and burdensome, requiring a review of its criteria. Full article

The feasibility of using the HiPerDiF (high performance discontinuous fibre) method to manufacture highly aligned discontinuous fibres intermingled hybrid composites with flax and reclaimed carbon fibres (rCF), and the potential benefits of so doing, are investigated in this paper. It is demonstrated that, despite their hydrophilic nature, flax fibres are not affected by this water-based process. Intermingled flax/rCF hybrid composites are characterised in terms of their tensile and vibrational response. It is concluded that natural/rCF fibre hybrid composites can be a viable solution for those applications where a reduction in primary mechanical properties, e.g., stiffness and strength, is an acceptable trade-off for the enhancement of secondary properties, e.g., noise, vibration, and harshness (NVH) mitigation, and the reduction of monetary costs. Full article

There is lack of uniform nomenclature for healthcare waste (HCW) globally, which could undermine efforts to develop and implement appropriate policies relating to healthcare waste management (HCWM) in developing countries. This study sought to understand the terminologies used to describe HCW, including their definitions, categories, classification, and how they align with those that are provided by the World Health Organization (WHO)’s global manual for HCWM from healthcare facilities. The study first identified terms from the existing literature; then, it conceptually mapped the literature, and identified gaps and areas of further inquiry. Six electronic databases—EBSCOhost, Open Access, ProQuest, PubMed, Web of Science, and Google Scholar were used to search for literature. A total of 112 studies were included in the study. Despite having various nomenclature for HCW globally that align with those provided by the WHO manual, the use of varying nomenclature could create confusion among healthcare workers in the quest of managing HCW properly, especially in low and middle-income countries (LMICs). Further studies must be conducted to determine how these terminologies are interpreted and implemented in practice by healthcare workers. This will help to understand how their implementation aligns with the recommendations provided by the WHO manual. Full article

Municipal solid waste incinerator fly ash (MSWI-FA) was used synergistically with volcanic ash (VA) to synthesize Geopolymer cement. The effects of the incorporation of 0%, 30%, and 50% of VA and the alkalinity of activating solution on the structure and properties were studied by using the X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), field emission gun scanning electron microscopy (FEG-SEM), and mechanical testing. The encapsulation efficiency of the cements was carried out by using a toxicity characteristic leaching procedure (TCLP). The geopolymerization of MSWI-FA promoted the formation of new minerals such as Thernadite (Na₂SO₄), Hydrocalumite (Ca₄Al₂O₆(CO₃)_0.67(SO₃)_0.33), C-S-H, and Faujasite-Na(Na₂Ca)_0.075(Al_0.3Si_0.7)O₂(H₂O)_0.22. The Geopolymer cement synthesized with the addition of 50% of VA at 6M NaOH concentration, which exhibited the most compact microstructure. This was the highest strength with the best encapsulation ability. The microstructure analysis of the MSWI-FA-VA system revealed the coexistence of C-S-H and N-A-S-H phases as the main cementitious binders. The TCLP results of cement vis a vis raw MSWI-FA showed the leaching of metals reduced to a great extent. This was much lower than the permissible limit fixed by the United States Environmental Protection Agency (USEPA) for the toxicity characteristic. Furthermore, an attempt was made to correlate the microstructure with mechanical properties. Full article