Recycling, Volume 3, Issue 4 (December 2018) – 13 articles

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

Improper disposal of waste cooking oil into sewer systems is harmful to the environment. Through the selective collection, this highly polluting residue can be handled in a less harmful way. The present study presents an action plan for a public school in the Region of Médio Paraíba Fluminense of the state of Rio de Janeiro, Brazil to serve as a voluntary delivery point in a reverse logistics chain for waste cooking oil. A case study method with semi-structured interviews was carried out with agents who are part of the chain, including the government, commercial residue generators, collectors, the biodiesel production industry, the community, and teachers and students of the public school. Even though the reverse supply chain for waste cooking oil in the region lacks structure, this study showed that the actors were interested in correctly disposing of waste cooking oil through partnerships and agreements. In addition to the environmental benefits, environmental education actions in public schools, such as the one in this study, can help raise student awareness of issues relative to citizenship and social responsibility and promote employment and income opportunities for recyclable material collector cooperatives and industries that use waste cooking oil as raw material. Full article

The production of consumption goods made of elastomers is increasing day by day, producing large amounts of vulcanized/cured residues which constitute a serious socio-environmental problem. An option for companies that produce elastomeric residues is their incorporation in the formulations, by producing polymeric blends with ground waste elastomers. Therefore, this work aims to prepare polymeric blends composed of raw natural rubber (NR)/ground waste NR in different concentrations. The influence of vulcanization reversion as result of additional heating during compression molding on the mechanical properties of the blends was analyzed, and the relationship among vulcanization characteristics, dynamic-mechanical, morphology and mechanical properties of blends was also determined. Full article